Uriitod Stales
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati OH 4B2G8
EPA/600/2-88/052
September 1988
Research and Development
&EPA
Lining of Waste
Containment and
Other Impoundment
mam m | H ^ •
Facilities
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EPA/600/2-88/052
September 1988
LINING OF WASTE CONTAINMENT
AND OTHER IMPOUNDMENT FACILITIES
by
Matrecon, Inc.
815 Atlantic Avenue
Alameda, California 94501
Project Officer
Robert Landreth
Waste Minimization Destruction and
Disposal Research Division
Risk Reduction Engineering Laboratory
Cincinnati, OH 45268
RISK REDUCTION ENGINEERING LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OH 45268
Envin-ominntal Protection Agency
.,-. 15, '.'!:rary (5PL-16)
.- • -'.i-n Street, Eoom 1670
.,u, lia 60604
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DISCLAIMER
The information in this document has been funded wholly or in part
by the United States Environmental Protection Agency under Contract No.
68-03-3265 to Matrecon, Inc. It has been subjected to the Agency's peer
and administrative review, and it has been approved for publication as an
EPA document. Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.
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FOREWORD
Today's rapidly developing and changing technologies and industrial
products and practices frequently carry with them the increased generation of
solid and hazardous wastes. These materials, if improperly dealt with, can
threaten both public health and the environment. Abandoned waste sites and
accidental releases of toxic and hazardous substances to the environment also
have important environmental and public health implications. The Risk
Reduction Engineering Laboratory assists in providing an authoritative
and defensible engineering basis for assessing and solving these problems.
Its products support the policies, programs and regulations of the Environ-
mental Protection Agency, the permitting and other responsibilities of State
and local governments and the needs of both large and small businesses in
handling their wastes responsibly and economically.
This report describes and details the major aspects of flexible mem-
brane liners and other materials used in the construction of containment
units for the storage or disposal of hazardous and/or nonhazardous wastes
or substances. Various procedures are presented as to the selection,
manufacture, construction, and use of the major types of flexible membrane
liners and ancillary materials to minimize the possibility of adverse
environmental impact.
E. Timothy Oppelt, Acting Director
Risk Reduction Engineering Laboratory
m
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ABSTRACT
This technical resource document provides current technological infor-
mation on liner and cover systems for waste storage and disposal units.
Liner systems serve to control the release of liquid and gaseous waste
components into the environment whereas cover systems, which are constructed
during the closure of a landfill, serve to prevent liquids from entering the
landfill, thereby reducing the potential for leachate generation. The
various materials used in the construction of these systems are discussed,
with particular emphasis on polymeric flexible membrane liners (FMLs). The
types and properties of wastes that may be impounded .in land storage and
disposal units and the constituents of these wastes that can affect lining
materials are discussed. The conditions inside a containment unit are de-
scribed, including the mechanisms of constituent transport within and out of
a unit and the service conditions for a lining system in different types of
containment units. The properties of FMLs and other materials of construc-
tion for waste containment units are discussed, and the effects of exposing
these materials to simulated and actual service conditions are presented.
Elements of the design, specifications, construction, quality assurance, and
maintenance of a lined waste containment unit are discussed. Costs for the
components of a lining system, including their installation and construction,
are presented. Several test methods that were useful in determining waste/
FML compatibility are included. A representative list of organizations in
the liner industry is presented as an appendix.
IV
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PREFACE
Subtitle C of the Resource Conservation and Recovery Act (RCRA) requires
the U. S. Environmental Protection Agency (EPA) to establish a Federal
hazardous waste management program. This program must ensure that hazardous
wastes are handled safely from generation until final disposition. EPA
issued a series of hazardous waste regulations under Subtitle C of RCRA that
are published in Title 40 Code of Federal Regulations (CFR) Parts 260 through
265 and Parts 122 through 124.
Parts 264 and 265 of 40 CFR contain standards applicable to owners/
operators of all facilities that treat, store, or dispose of hazardous
wastes. Wastes are identified or listed as hazardous under 40 CFR Part 261.
Part 264 standards are implemented through permits issued by authorized
States or EPA according to 40 CFR Part 122 and Part 124 regulations. Land
treatment, storage, and disposal (LTSD) regulations in 40 CFR Part 264 issued
on July 26, 1982, and July 15, 1985, establish performance standards for
hazardous waste landfills, surface impoundments, land treatment units, and
wastepiles. Part 265 standards impose minimum technology requirements on the
owners/operators of certain landfills and surface impoundments.
EPA is developing three types of documents to assist preparers and
reviewers of permit applications for hazardous waste land disposal facili-
ties. These are RCRA Technical Guidance Documents (TGDs), Permit Guidance
Manuals, and Technical Resource Documents (TRDs). Although emphasis is given
to hazardous waste facilities, the information presented in these documents
may be used for designing, constructing, and operating nonhazardous waste
LTSD facilities as well.
The RCRA TGDs present design, construction, and operating specifications
or evaluation techniques that generally comply with or demonstrate compliance
with the Design and Operating Requirements and the Closure and Post-Closure
Requirements of Part 264. The Permit Guidance Manuals are being developed to
describe the permit application information the Agency seeks and to provide
guidance to applicants and permit writers in addressing information require-
ments. These manuals will include a discussion of each step in the permit-
ting process and a description of each set of specifications that must be
considered for inclusion in the permit.
The TGDs and Permit Guidance Manuals present guidance, not regulations.
They do not supersede the regulations promulgated under RCRA and published in
-------
the CFR. Instead, they provide recommendations, interpretations, sugges-
tions, and references to additional information that may be used to help
interpret the requirements of the regulations. The recommendation of
methods, procedures, techniques, or specifications in these manuals and
documents is not intended to suggest that other alternatives might not
satisfy regulatory requirements.
The TRDs present summaries of state-of-the-art technologies and evalua-
tion techniques determined by the Agency to constitute good engineering
designs, practices, and procedures. They support the RCRA TGDs and Permit
Guidance Manuals in certain areas by describing current technologies and
methods for designing hazardous waste facilities or for evaluating the
performance of a facility design. Whereas the RCRA TGDs and Permit Guidance
Manuals are directly related to the regulations, the information in the TRDs
covers a broader perspective and should not be used to interpret the re-
quirements of the regulations.
This document is a Technical Resource Document. It is a thoroughly
revised edition of the 1983 edition which was published by the Municipal
Environmental Research Laboratory of the EPA. This edition reflects the
changes in regulations and the advances in waste containment technology that
have taken place since 1983. It also reflects the considerable research that
has been performed in the area of waste containment and the experience that
has been gained in this technology. This new edition incorporates the many
responses to comments received in the peer review of the draft. This docu-
ment supersedes the March 1983 edition.
Comments on this revised publication will be accepted at any time. The
agency intends to update these TRDs periodically based on comments received
and/or the development of new information. Comments on any of the current
TRDs should be addressed to Docket Clerk, Room S-269(c), Office of Solid
Waste and Emergency Response (WH-562), U.S. Environmental Protection Agency,
401 M Street, S.W., Washington, D.C., 20460. Communications should identify
the document by title and number (e.g., "Lining of Waste Containment and
Other Impoundment Facilities", SW-870).
VI
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CONTENTS
FOREWORD ill
PREFACE v
ABSTRACT vi1
LIST OF FIGURES xxxv
LIST OF TABLES xlix
ABBREVIATIONS AND SYMBOLS Ixiii
ACKNOWLEDGMENTS Ixxi
CHAPTER 1. INTRODUCTION
1.1 Background 1-1
1.2 Purpose of This Technical Resource Document 1-3
1.3 Scope 1-4
1.4 References 1-7
CHAPTER 2. CHARACTERISTICS OF WASTE LIQUIDS AND LEACHATES
2.1 Introduction 2-1
2.2 General Description and Classification of
Leachates and Waste Liquids 2-3
2.2.1 Types of Leachates 2-3
2.2.2 Types of Waste Liquids 2-5
2.2.3 Constituents of Leachates and Waste Liquids 2-6
2.2.4 Composition of Actual Hazardous Waste Leachates 2-8
2.3 Characterizing Hazardous Wastes and Waste Constituents 2-13
2.4 Impact of Current and Future Waste Management Practice 2-16
on Composition of Wastes and Waste Liquids that are
Stored or Disposed of on Land
vi i
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2.4.1 Waste Minimization by Recycling and Source 2-17
Reduction
2.4.2 Incineration of Wastes 2-18
2.4.3 Restrictions on the Type of Wastes 2-22
2.4.4 Application of Solidification/Stabilization 2-22
Technologies
2.4.5 Miscellaneous Possible Hazardous Wastes 2-23
2.5 Description of Wastes from Specific Sources 2-23
2.6 Hazardous Substances in Storage Facilities Requiring 2-24
Secondary Containment
2.7 References 2-25
CHAPTER 3. WASTE CONTAINMENT ON LAND AND CONSTITUENT TRANSPORT
WITHIN AND OUT OF A CONTAINMENT UNIT
3.1 Introduction 3-1
3.2 Physical and Chemical Attributes of Waste Liquids, 3-3
Gases, and Vapors
3.3 Characteristics of Barrier Materials 3-4
3.3.1 Introduction 3-4
3.3.2 Permeation Through Porous Materials 3-4
3.3.3 Permeation Through Nonporous Materials 3-7
3.4 Transport Processes and Driving Forces Involved 3-11
in the Migration of Chemical Species
3.5 Transport of Waste Constituents Within a Closed Landfill 3-12
3.6 Escape of Constituents from Waste Storage and 3-12
Disposal Facilities
3.7 References 3-14
CHAPTER 4. FMLS AND OTHER CONSTRUCTION MATERIALS
4.1 Introduction 4-1
4.2 Polymeric Materials 4-3
4.2.1 Basic Characteristics of Polymeric Materials 4-4
vi i i
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4.2.1.1 Composition and Structure of Polymers 4-6
4.2.1.2 Polymers Vary in Modulus and in Elongation 4-7
at Break
4.2.1.3 Polymers are Viscoelastic and Sensitive to 4-8
Temperature and Rate of Deformation
4.2.1.4 Amorphous and Crystalline Phases in Semi- 4-9
crystalline Polymers
4.2.1.5 Polymers Tend to Creep and to Relax Under 4-9
Stress
4.2.1.6 High Coefficient of Linear Thermal 4-10
Expansion
4.2.1.7 Importance of Thermal and Strain History 4-10
4.2.1.8 Multiaxial Straining of Polymer Materials 4-11
4.2.1.9 Broad Range of Permeability 4-12
4.2.1.10 Polymers are Sensitive to Organic Liquids 4-12
and Vapors
4.2.1.11 Resistance to Stress-Cracking and 4-12
Static Fatigue
4.2.1.12 Effects of Long-Term Exposure 4-13
4.2.1.13 Combinations of Properties in Polymeric 4-15
Compositions
4.2.2 Polymeric Flexible Membrane Liners (FMLs) 4-16
4.2.2.1 Polymers Used in Currently Available 4-18
Polymeric FMLs
4.2.2.1.1 Chlorinated polyethylene 4-19
4.2.2.1.2 Chlorosulfonated polyethylene 4-20
4.2.2.1.3 Polyester elastomers 4-21
4.2.2.1.4 Polyethylene 4-21
4.2.2.1.5 Polyvinyl chloride 4-25
4.2.2.2 FML Manufacture 4-26
4.2.2.2.1 Compounding of FML compositions 4-26
ix
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4.2.2.2.2 Forming processes 4-27
4.2.2.3 Seaming of Flexible Polymeric FMLs 4-29
4.2.2.3.1 Solvent methods 4-33
4.2.2.3.2 Thermal methods 4-36
4.2.2.3.3 Other bonding methods for
seaming FMLs 4-39
4.2.2.3.4 Repairing and seaming of exposed 4-40
FMLs
4.2.2.4 Properties and Characteristics of FMLs 4-41
Important to their Function in Liner
Systems
4.2.2.4.1 Permeability 4-41
4.2.2.4.2 Mechanical properties 4-59
4.2.2.4.3 Chemical properties 4-75
4.2.2.4.4 Durability 4-81
4.2.2.5 Testing and Laboratory Evaluation of FMLs 4-85
4.2.2.5.1 Analytical properties of 4-88
polymeric FMLs
4.2.2.5.2 Physical-mechanical properties 4-107
4.2.2.5.3 Permeability characteristics 4-118
4.2.2.5.4 Tests to measure the effects of 4-118
environmental or accelerated
exposure
4.2.2.5.5 Performance tests 4-126
4.2.2.6 Fingerprinting of FMLs 4-135
4.2.3 Geotextiles 4-140
4.2.3.1 Polymer Types Used in Manufacture 4-141
4.2.3.2 Geotextile Fibers and Fabrics 4-141
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4.2.3.3 Filtration Principles 4-141
4.2.3.3.1 Adequate permittivity 4-142
4.2.3.3.2 Soil retention 4-144
4.2.3.4 Long-Term Compatibility 4-144
4.2.3.4.1 Soil clogging 4-145
4.2.3.4.2 Biological clogging 4-145
4.2.3.4.3 Chemical degradation 4-145
4.2.3.4.4 Burial degradation 4-145
4.2.3.5 Other Considerations 4-146
4.2.4 Geogrids 4-146
4.2.4.1 Polymer Types 4-147
4.2.4.2 Various Available Styles 4-147
4.2.4.3 Long-Term Considerations 4-148
4.2.5 Geonets 4-148
4.2.5.1 Polymer Types 4-149
4.2.5.2 Manufacturing and Types of Geonets 4-149
4.2.5.3 Drainage Design 4-150
4.2.5.4 Long-Term Considerations 4-154
4.2.5.4.1 Material effects 4-154
4.2.5.4.2 Creep of net 4-154
4.2.5.4.3 Creep of adjacent materials 4-154
4.2.5.4.4 Chemical effects 4-154
4.2.5.4.5 Biological effects 4-154
4.2.6 Geocomposites 4-156
4.2.6.1 Polymer Types 4-156
4.2.6.2 Types of Geocomposites 4-157
xi
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4.2.6.3 Drainage Design 4-157
4.2.6.4 Long-Term Considerations 4-158
4.2.7 Pipes and Fittings 4-160
4.3 Admixed Liner Materials 4-164
4.3.1 Hydraulic Asphalt Concrete 4-165
4.3.1.1 Permeability of Hydraulic Asphalt Concrete 4-165
4.3.1.2 Durability of Asphalt Concrete 4-167
4.3.1.3 Evaluation of Asphaltic Liner Materials 4-167
4.3.1.4 Installation Characteristics 4-168
4.3.2 Soil Cement 4-168
4.3.2.1 Permeability of Soil Cement 4-169
4.3.2.2 Durability of Soil Cement 4-170
4.3.2.3 Evaluation of Soil-Cement Materials 4-172
4.4 Sprayed-On FMLs 4-173
4.4.1 Air-Blown Asphalt FMLs 4-173
4.4.2 Emulsified Asphalt FMLs 4-175
4.4.3 Styrene-Butadiene Rubber (SBR)/Asphalt FMLs 4-175
4.4.4 Urethane-Modified Asphalt FMLs 4-176
4.5 References 4-176
CHAPTER 5. EXPOSURE OF POLYMERIC FMLS AND RELATED MATERIALS
OF CONSTRUCTION IN SIMULATED-SERVICE ENVIRONMENTS
5.1 Introduction 5-1
5.2 Environments in Treatment, Storage, and Disposal Facilities 5-3
(TSDFs) Encountered by FMLs and Ancillary Materials During
Construction and Service
5.2.1 Introduction 5-3
xn
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5.2.2 Environments Encountered During Construction 5-3
5.2.3 MSW Landfills 5-5
5.2.4 Surface Impoundments 5-5
5.2.5 Hazardous Waste Landfills 5-7
5.2.6 Waste Piles 5-11
5.2.7 Heap Leach Pads and Ponds 5-11
5.2.8 Secondary Containment Facilities 5-16
5.2.9 Uranium Tailings Ponds 5-17
5.3 Principal Environmental Stresses Encountered by FMLs and 5-17
Other Materials of Construction in Service in TSDFS
5.3.1 Chemical Stresses 5-18
5.3.2 Physical Stresses 5-20
5.3.3 Combination of Chemical and Physical Stresses 5-21
5.3.4 Biological Stresses 5-22
5.4 Effects of Chemical Stresses on FMLs and Ancillary 5-22
Construction Materials
5.4.1 Simulation Tests of FMLs 5-23
5.4.1.1 Exposure to MSW Leachate in Landfill 5-23
Simulators
5.4.1.2 Exposure to Hazardous Wastes in One-Sided 5-31
Exposure Cells
5.4.1.2.1 Butyl rubber 5-45
5.4.1.2.2 Chlorinated polyethylene 5-46
(CPE)
5.4.1.2.3 Chlorosulfonated polyethylene 5-46
(CSPE)
5.4.1.2.4 Elasticized polyolefin (ELPO) 5-47
5.4.1.2.5 Ethylene propylene (EPDM) 5-47
5.4.1.2.6 Neoprene 5-47
xin
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5.4.1.2.7 Polyester elastomer (PEL) 5-48
5.4.1.2.8 Polyvinyl chloride (PVC) 5-48
5.4.1.3 Exposure to Wastes from Coal-Fired Electric 5-48
Power Plants
5.4.1.4 Exposure in Tub Tests 5-50
5.4.1.4.1 Testing of first failed ELPO liner 5-52
exposed to "Oil Pond 104" waste
5.4.1.4.2 Recovery and testing of the second 5-53
failed ELPO liner exposed to "Oil
Pond 104" waste
5.4.1.4.3 Testing of the neoprene liner 5-54
exposed to "Oil Pond 104" waste
5.4.1.4.4 Summary of results of testing other 5-55
FMLs exposed in roof tubs
5.4.1.4.5 Discussion of results 5-56
5.4.1.5 Simultaneous Exposure to Simulated Tailings 5-56
and Stress
5.4.1.6 Exposure in Pouch Tests 5-60
5.4.1.6.1 Tests of FML pouches containing 5-62
MSW leachate
5.4.1.6.2 Tests of FML pouches containing 5-64
hazardous waste liquids
5.4.1.6.3 Overview of pouch test results 5-71
5.4.1.7 Permeability of FMLs to Mixtures of Organics 5-73
and Aqueous Solutions
5.4.1.7.1 Permeability to mixtures of 5-73
organics
5.4.1.7.2 Permeability to aqueous solutions 5-75
of organics
5.4.2 Immersion Tests of FMLs 5-80
5.4.2.1 Immersion in MSW Leachate 5-82
xiv
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5.4.2.2 Immersion of FMLs in Hazardous Wastes and 5-85
Selected Test Liquids
5.4.2.2.1 Chlorinated polyethylene (CPE) 5-91
5.4.2.2.2 Chlorosulfonated polyethylene 5-95
(CSPE)
5.4.2.2.3 Ethylene propylene rubber 5-96
(EPDM)
5.4.2.2.4 Polyester elastomer (PEL) 5-97
5.4.2.2.5 Polyethylene (PE) 5-97
5.4.2.2.6 Polyvinyl Chloride (PVC) 5-98
5.4.2.3 Immersion in Test Liquids 5-99
5.4.2.3.1 Equilibrium swelling of FMLs 5-99
and FML-related compositions
in test liquids
5.4.2.3.2 Immersion testing of FMLs to 5-103
develop chemical compatibility
requirements
5.4.2.3.3 Immersion testing of seams 5-113
5.4.3 Compatibility Testing of FMLs 5-117
5.4.3.1 Compatibility Testing Performed with 5-121
Actual and Synthetic Leachates Con-
taining Organics
5.4.3.1.1 Compatibility test of an HOPE 5-123
FML performed with an actual
leachate spiked with selected
orgranics
5.4.3.1.2 Compatibility test of an HOPE 5-124
FML performed with DI water
spiked with organics
5.4.3.2 Evaporation of Volatile Organics 5-127
from Water Solutions and Exposed FMLs
5.4.3.2.1 Evaporation of volatile organics 5-127
from aqueous solutions
xv
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5.4.3.2.2 Evaporation of organics from 5-128
saturated FML specimens
5.5 Effects of Mechanical Stress 5-130
5.5.1 Large-Scale Hydrostatic Testing Over a Subgrade 5-131
5.5.2 Holes in FMLs 5-136
5.5.3 In-Service Drainage Capability of Geotextiles 5-139
5.5.3.1 Hydraulic Transmissivity of Geotextiles 5-140
5.5.3.2 Hydraulic Transmissivity of Geonets 5-141
Under Different Boundary Conditions
5.6 Biodegradation and Other Biological Stresses 5-146
5.7 Accelerated Aging and Weathering Tests 5-147
5.7.1 Roof Exposure Tests 5-147
5.7.2 EMMAQUA Testing 5-152
5.8 Compatibility Testing of FMLs in Actual Waste 5-154
Containment Units
5.9 Simulated Exposure Testing of Admixed Liner Materials 5-154
5.9.1 Exposure to MSW Leachate 5-154
5.9.2 Exposure to Hazardous Wastes 5-156
5.10 Simulated Exposure Testing of Sprayed-on FMLs 5-158
5.10.1 Exposure to MSW Leachate 5-158
5.10.2 Exposure to Hazardous Waste 5-160
5.11 References 5-160
CHAPTER 6. FMLS AND RELATED MATERIALS OF CONSTRUCTION
IN SERVICE ENVIRONMENTS
6.1 Introduction 6-1
6.2 Objectives of Field Studies of Liner System 6-2
in Containment Units
6.3 Potential Modes for FML Failure and Contributing 6-6
Factors
xv i
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6.3.1 Types of FML Failures 6-7
6.3.1.1 Changes in the Permeability Characteristics 6-7
of the FML
6.3.1.2 Mechanical Failure 6-7
6.3.1.2.1 Puncture 6-7
6.3.2.1.2 Tear 6-7
6.3.1.2.3 Cracks 6-7
6.3.1.2.4 Abrasion 6-7
6.3.1.2.5 Seam failure 6-8
6.3.2 Factors That Could Contribute to FML Failure 6-8
6.3.2.1 Material Factors 6-8
6.3.2.1.1 Chemical incompatibility 6-8
6.3.2.1.2 Creep 6-10
6.3.2.1.3 Shrinkage 6-10
6.3.2.1.4 Tendency towards environmental 6-11
stress-cracking
6.3.2.2 Factors Related to the Site 6-11
6.3.2.2.1 Subsidence 6-11
6.3.2.2.2 Generation of gases underneath 6-11
the unit
6.3.2.2.3 Water table 6-12
6.3.2.3 Design and Engineering Factors 6-12
6.3.2.4 Factors Related to Construction 6-12
6.3.2.4.1 Poor subgrade compaction 6-12
6.3.2.4.2 Inadequate finishing of the 6-13
subgrade
6.3.2.4.3 Poor quality of the seams 6-13
XVII
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6.3.2.5 Factors Related to Quality Control/Quality 6-13
Assurance
6.3.2.6 Factors Related to the Service Environment 6-13
6.3.2.6.1 Weathering 6-13
6.3.2.6.2 Wind and wave action 6-14
6.3.2.6.3 Biodegradation 6-14
6.4 Difficulties in Finding Available Sites For Study 6-14
and Material Sampling
6.5 Field Studies of FMLs 6-15
6.5.1 Field Studies Conducted by Matrecon 6-15
6.5.1.1 PVC FML in MSW Demonstration Landfill 6-15
6.5.1.2 PVC FML in Sludge Lagoon 6-18
6.5.1.3 CPE, CSPE, and LDPE FMLs in a Pilot- 6-19
Scale MSW
6.5.1.4 CSPE FML in Pilot-Scale MSW Landfill Cells 6-22
6.5.1.5 HOPE FML in a Hazardous Waste Lagoon 6-24
6.5.1.5.1 Sampling and analysis of 6-24
the waste
6.5.1.5.2 Sampling of the FML liner 6-26
6.5.1.5.3 Analytical and physical testing 6-28
of the FML samples
6.5.1.5.4 Discussion and conclusions 6-32
6.5.1.6 PVC FML in an Industrial Sludge Lagoon 6-33
6.5.1.6.1 Inspection and testing of 6-35
the FML samples
6.5.1.6.2 Potential Use of soil-exposed 6-37
specimen as a control
6.5.1.6.3 Inspection and testing of the 6-37
seams
6.5.1.6.4 Conclusions 6-41
xvii i
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6.5.1.7 PVC FML from a MSW Landfill
6.5.1.8 EPDM FML f
"Red Water
6.5.1.8.1
6.5.1.8.2
6.5.1.8.3
6.5.1.8.4
6.5.1.8.5
6.5.1.8.6
om Emergency Ponds for
Description of the basin and
the FML
Sampling of the FML
Testing of FML samples
Inspection and testing
of the seams
Selection of a baseline
reference
Results and discussion
6.5.1.9 PVC FML from an Industrial Landfill
6.5.2 Field Studies Conducted by Giroud
6.5.2.1 CSPE FML from Evaporation Pond at a
Chemical Plant (Giroud, 1984a - Case 1)
6.5.2.2 PVC FML from a Mining Operation -
Uranium Tailings (Giroud, 1984a -
Case 2; Gi
6.5.2.2.1
6.5.2.2.2
6.5.2.2.3
Tailings
6.5.2.4 Asphaltic
(Giroud,
roud, 1984b)
Problems
Samples and testing
Discussion of results
6.5.2.3 PVC FML for a Mining Operation—Uranium
Giroud, 1984a - Case 3)
FML in a Potable Water Reservoir
984a - Case 4)
6.5.2.5 PVC-OR FML in Salt Ponds (Giroud, 1984a -
Case 6)
6.5.2.6 Butyl Rubper in Industrial Storage Ponds
(Giroud, 1984a - Case 8)
6.5.2.7 Butyl Rubber FML in Potable Water
Reservoir (Giroud, 1984a - Case 11)
6-42
6-44
6-44
6-44
6-47
6-47
6-49
6-49
6-54
6-55
6-55
6-55
6-57
6-59
6-61
6-61
6-63
6-63
6-64
6-66
xix
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6.5.2.8 PVC and CPE FMLs in a Wastewater Impound- 6-66
ment (Giroud, 1984a - Case 26)
6.5.3 Field Studies Conducted by Ghassemi 6-67
6.5.3.1 ELPO FML in Ponds Containing Electrolytic 6-67
Metal Process Liquor (Ghassemi et al,
1984 - Case Study No. 1)
6.5.3.2 PVC and CPE FMLs in Wastewater and Rinse 6-67
Water Ponds (Ghassemi et al, 1984 - Case
Study No. 2)
6.5.3.3 EPDM and PVC FMLs in Evaporation and 6-69
Cooling Ponds - Case Study No. 4
6.5.3.4 EPDM FMLs in Wastewater Ponds (Ghassemi 6-69
et al, 1984 - Case Study No. 8)
6.5.3.5 CSPE and PVC FMLs in Uranium Tailings Pond 6-69
(Ghassemi et al, 1984 - Case Study No. 9)~
6.5.4 Performance of PVC FMLs as Canal Linings 6-70
6.5.5 Analysis of a Survey of FML-Lined Waste Containment 6-71
Units
6.6 Field Studies of Geotextiles 6-76
6.6.1 Field Study No. 1 6-76
6.6.2 Field Study No. 2 6-78
6.7 Field Studies of Leachate Collection and Removal Systems 6-81
6.8 Observations and Limited Conclusions from Studies of the 6-82
In-Service Performance of FMLs and Ancillary Materials
In Containment Applications
6.8.1 Introduction 6-82
6.8.2 Performance of Components 6-84
6.8.2.1 Liner System 6-84
6.8.2.2 Leachate Collection and Removal Systems 6-85
6.8.2.3 Supporting Structures and Earthworks 6-85
6.8.3 Correlation of Field Performance and Laboratory 6-86
Assessment of FMLs
xx
-------
6.8.4 Factors That Affect the Performance of a
Containment Unit
6.8.5 Need for In-Service Performance Information
on Waste Containment Units
6.9 References
CHAPTER 7. DESIGN OF LINED WASTE SJORAGE AND DISPOSAL UNITS
7.1 Introduction
7.2 Types of Constructed Containment Units
7.3 Factors in Designing a Li led Containment Unit
7.3.1 Site-Specific Factors in Designing a Waste
Containment Unit
7.3.1.1 Operational Factors
7.3.1.1.1
Purpose of the unit
7.3.1.1.2 Characteristics of the waste
I to be contained
7.3.1.1.3 Configuration and dimensions
of the unit
7.3.1.1.4
Recycling/recovery operations
7.3.1.1.5J Berm width requirements
7.3.1.1.6 Inflow/outflow/overflow
j conveyances
i
7.3.1.1.^ Estimated leachate volume in a
: landfill
7.3.1.2 Hydrogeological Factors
i
7.3.1.2.1 Characteristics of in situ
soils
7.3.1.2.!! Subgrade characteristics
7.3.1.2.3 Presence of hydrologic pathways
7.3.1.2.4 Location and type of bedrock
i
I
7.3.1.2.5 Seismic history of area and
proximity to faults
6-87
6-87
6-88
7-1
7-2
7-6
7-6
7-6
7-6
7-6
7-9
7-9
7-9
7-9
7-10
7-13
7-13
7-13
7-14
7-14
7-15
xxi
-------
7.3.1.2.6 Location of uppermost aquifer 7-15
7.3.1.2.7 Surface and groundwater 7-15
drainage considerations
7.3.1.2.8 Floodplain level 7-15
7.3.1.2.9 Site topography 7-15
7.3.1.3 Climatological Factors 7-16
7.3.1.3.1 Prevailing wind speed and 7-16
direction
7.3.1.3.2 Ambient temperature 7-16
7.3.1.4 Biological Factors 7-16
7.3.1.4.1 Local vegetation 7-16
7.3.1.4.2 Presence of indigenous 7-17
burrowing animals
7.3.1.4.3 Presence of microorganisms 7-17
7.3.1.4.4 Presence of organic material 7-18
in the subgrade soil
7.3.2 Statutory and Regulatory Requirements and EPA 7-18
Guidance for Waste Containment Units
7.3.2.1 Performance Criteria for Solid Waste TSDFs 7-19
7.3.2.2 Statutory and Regulatory Requirements for 7-19
the Design of Hazardous Waste TSDFs
7.3.2.2.1 Design Requirements for 7-20
Hazardous Waste Piles
7.3.2.2.2 Design Requirements for Hazardous 7-22
Waste Surface Impoundments
7.3.2.2.3 Design Requirements for Hazardous 7-22
Waste Landfills
7.3.2.3 Draft EPA Guidance on Hazardous Waste 7-22
Containment Units
7.3.2.3.1 Draft EPA Guidance on Double 7-23
Liner Systems
xxn
-------
7.3.2.3.2 praft EPA Guidance on Final
^over Systems
7.4 Site Investigation
7.5 Design of Components of a lining System
7.5.1 Foundation Design
7.5.2 Design of Embankment
7.5.3 Design of the Bottom
7.5.3.1 Design of the Soil Component
7.5.3.1.1
7.5.3.1.2
7.5.3.1.3
7.5.3.1.4
7.5.3.1.5
Composite Liner
Soil permeability
Relationship between soil
sroperties, compactive behavior,
and permeability
Selection of soil for use as a
lining material
Design and specifications for a
soil liner
:ield verification of design
specifications
7.5.3.2 Design of FML Component of Bottom Composite
Liner
7.5.3.2.1 Performance requirements of an FML
[
7.5.3.2.2 Selection of the FML
7.5.3.2.3
Effect of FML Selection on design
7.5.3.2.4 FML layout
7.5.3.2.5
Attachment to penetrations and
appurtenances
7.5.3.3 The Interface Between the Soil and
FML Components
7.5.4 Design of the Secondary Leachate Collection
and Removal System (LCRS)
7-26
7-27
7-30
7-31
7-33
7-40
7-41
7-42
7-43
7-49
7-52
7-53
7-56
7-57
7-61
7-61
7-62
7-62
7-64
7-64
xxm
-------
7.5.4.1 Pipe Used in an LCRS 7-67
7.5.4.2 Drainage Systems and the Design of a 7-69
Secondary LCRS
7.5.4.2.1 Granular drainage systems 7-69
7.5.4.2.2 Synthetic drainage systems 7-73
7.5.4.3 Bottom Slope 7-75
7.5.4.4 System Layout 7-76
7.5.4.5 Sump Requirements 7-77
7.5.4.6 Auxiliary Cleanouts 7-81
7.5.5 Design of the Top Liner 7-82
7.5.5.1 An FML-only Top Liner 7-82
7.5.5.1.1 Interaction between an FML 7-83
and a drainage layer
7.5.5.1.2 FML thickness considerations 7-83
7.5.5.2 Composite Top Liner 7-84
7.5.6 Design of a Primary Leachate Collection 7-87
and Removal System (LCRS)
7.5.7 Design of Ancillary Components 7-91
7.5.7.1 Anchor Trenches 7-92
7.5.7.2 Penetrations 7-92
7.5.7.3 Gas Vents 7-95
7.5.7.4 Liner Protection from Pipe Outfall 7-96
7.5.7.5 Aeration System 7-96
7.5.7.6 Protective Soil Covers 7-99
7.5.7.7 Use of Coupons to Monitor the Liner 7-102
and Other Materials of Construction
During Service
xxiv
-------
7.5.7.8 Groundwater
7.5.8 Design of a Landfill
7.6 References
CHAPTER 8. SPECIFICATIONS FOR THE MA
OF WASTE STORAGE AND DISP
8.1 Introduction
8.2 Specification Document
8.3 Technical Specifications
8.4 Specifications for Earthwor
Components of FML/Soil Comp
Monitoring Wells
Cover System
ERIALS AND CONSTRUCTION
)SAL UNITS
s, Embankments, and Soil
Dsite Liners
8.4.1 Specifications for tpe Foundation and Embankments
,he Foundations and the
8.4.1.1 Purpose of
Embankments
8.4.1.2 Material Sp
and the Embankments
8.4.1.3 Specificati
Foundation
8.4.1.4 Embankment
8.4.1.5 Requirement
to Verify
Compaction
8.4.1.6 Specificati
8.4.1.7 Construction
8.4.2 Specifications for C
Composite Bottom Lin
8.4.2.1 Purpose of
Bottom Line
8.4.2.2 Material Sp
Component c
8.4.2.3 Requirement
Component c
ecifications for Foundations
ons for Excavation and
Construction
Construction Specifications
for Test Fill Construction
Embankment Design and
3rocedure
)ns for Appurtenances
Quality Control and Assurance
mpacted Soil Component of a
r of a Double Liner System
the Soil Component of a Composite
cifications for the Soil
a Bottom Composite Liner
for Construction of the Soil
a Composite Bottom Liner
7-102
7-103
7-108
8-1
8-1
8-3
8-4
8-5
8-5
8-5
8-6
8-6
8-7
8-7
8-7
8-7
8-8
8-8
8-8
jxxv
-------
8.4.2.4 Requirement for Test Fill to Verify 8-10
Soil Liner Specifications
8.4.2.5 Requirements for Miscellaneous Components 8-11
of the Soil Liner and Earthworks
8.4.2.6 Acceptance of Soil Surface as Bedding for 8-11
an FML
8.4.2.7 Construction Quality Control and Assurance 8-12
8.4.3 Specifications for the Compacted Soil Component of 8-12
the Upper Composite Liner of a Double Liner System
8.4.3.1 Purpose of the Soil Component of a Composite 8-12
Top Liner
8.4.3.2 Material Specifications for the Soil 8-12
Component of a Composite Top Liner
8.4.3.3 Construction Specifications for the Soil 8-12
Component of a Top Composite Liner
8.4.3.4 Construction Quality Control and Quality 8-13
Assurance
8.4.4 Specifications for the Subgrade Below an FML 8-13
8.4.4.1 Purpose of Bedding Layer for an FML 8-13
8.4.4.2 Material Specifications for a Bedding 8-13
Layer for an FML
8.4.4.3 Construction Specifications for a Bedding 8-14
Layer
8.4.4.4 Construction Quality Control and Quality 8-14
Assurance
8.4.5 Specifications for a Protective Soil Cover 8-14
8.4.5.1 Purpose of a Protective Soil Cover 8-14
8.4.5.2 Material Specifications for a Soil Cover 8-14
8.4.5.3 Construction Specifications for a 8-14
Protective Soil Cover
8.4.5.4 Construction Quality Control and Quality 8-14
Assurance
xxvi
-------
8.5 Specifications for FMLs
8.5.1 Purpose of an FML
8.5.2 Performance Requirements for an FML
i
8.5.3 Material Specifications for FMLs
8.5.4 Specifications for S
8.5.5 Installation Specifi
8.5.6 Specifications for 5
and Appurtenances
8.5.7 Specifications for Anchoring the FML
hipping and Storage of FMLs
cations for an FML
ealing the FML to Penetrations
8.5.8 Construction Quality
8.6 Specifications for Leachatt
I
8.6.1 Purpose and Performs
8.6.2 Material Specificati
8.6.3 Construction Specifi
Control and Quality Assurance
Collection and Removal Systems
nee Requirements
ons for an LCRS
cations for an LCRS
8.6.4 Construction Quality^ Control and Quality Assurance
8.7 Specifications for Final Cc
ver Systems
8.7.1 Purpose and Performance Specifications for
a Cover System
i
8.7.2 Specifications for 1fhe Components of a
Cover System i
I
8.7.2.1 Specificatjons for a Gas-Venting System
8.7.2.2 Specifications for the Low-permeability
Layer
8.7.2.3 Specificaf ons for Drainage Filter
Layers !
8.7.2.4 Specifications for the Vegetative Layer
8-15
8-15
8-15
8-16
8-19
8-19
8-20
8-20
8-20
8-20
8-21
8-22
8-24
8-24
8-25
8-25
8-26
8-26
8-27
8-27
8-27
-------
8.8 References 8-28
CHAPTER 9. CONSTRUCTION OF LINED WASTE STORAGE
AND DISPOSAL UNITS
9.1 Introduction 9-1
9.2 Earthworks 9-1
9.2.1 Excavation and Foundation Construction 9-2
9.2.2 Compaction of Soil 9-5
9.2.3 Construction of Embankments 9-10
9.2.4 Construction of Soil Component of a 9-11
Composite Liner
9.2.5 Fine Finishing of Soil Surfaces 9-14
9.3 Installation of FMLs 9-17
9.3.1 On-site Storage of Materials and Equipment 9-17
9.3.2 Equipment and Materials for Installing FMLs 9-19
9.3.3 Manpower Requirements for Installing an FML 9-26
9.3.4 Placement of an FML 9-29
9.3.5 Field Seaming of FMLs 9-35
9.3.6 Field Testing of Seams 9-41
9.3.7 Placement of a Protective Soil Cover on an FML 9-43
9.4 Construction of Leachate Collection and Removal 9-48
Systems (LCRSs)
9.4.1 Construction of a Secondary LCRS 9-49
9.4.2 Construction of a Primary LCRS 9-50
9.5 Anchoring/Sealing of an FML Around Structures/ 9-51
Penetrations
9.6 Construction of the Final Cover 9-52
xxvm
-------
9.7 Construction of Admix ar|d Sprayed-On Liners
9.7.1 Asphalt Concrete
9.7.2 Soil Cement
9.7.3 Concrete and Cemeint
9.7.4 Sprayed-on Liners;
9.8 References
CHAPTER 10. QUALITY ASSURANCE FOR
OF FML LINER SYSTEMS
10.1 Introduction
10.2 The Elements of a CQA P
THE CONSTRUCTION
10.2.1 Delineation of Responsibility and Authority
10.2.2 Statement of Qu
10.2.3 Design Specifications
10.2.4 Inspection Acti
an
lifications of CQA Personnel
ities to be Performed
10.2.5 Sampling Requirements
10.2.6 Acceptance/Rejection Criteria and Corrective
Measures
10.2.7 Documentation
10.3 CQA Inspection of Earthworks and Soil Liner Component(s)
of Composite Double Liners
10.3.1 Inspection of tie Foundation
10.3.2 Inspection of tie Embankments
10.3.3 Inspection of Soil Liners
10.4 CQA Inspection of FMLs
10.4.1 Control of Raw
Materials used in the
Manufacture of FMLs
10.4.2 Inspection of tie Manufactured FML Sheeting
10.4.3 Inspection of Fabricated Panels
9-55
9-55
9-57
9-57
9-59
9-62
10-1
10-2
10-2
10-3
10-3
10-4
10-5
10-6
10-7
10-7
10-7
10-8
10-9
10-12
10-13
10-14
10-18
XXIX
-------
10.4.4 Inspection of Transportation, Handling, 10-19
and Storage of FMLs
10.4.5 Inspection of FML Installation 10-21
10.4.5.1 Inspection of FML Placement 10-21
10.4.5.2 Inspection of FML Field Seams 10-22
10.4.5.3 Inspection of FML Anchors and 10-26
Attachments
10.4.5.4 Large-Scale Hydrostatic Leak- 10-27
Detection Test of Installed FML
10.4.5.5 Inspection of the Placement of 10-28
a Protective Cover Over the FML
10.5 Inspection of the Installation of the Leachate 10-28
Collection and Removal Systems
10.6 References 10-30
CHAPTER 11. MANAGEMENT, MONITORING, AND MAINTENANCE
OF LINED WASTE STORAGE AND DISPOSAL UNITS
11.1 Introduction 11-1
11.2 Standard Operating Procedures for a Waste Storage 11-2
and Disposal Unit
11.3 Information on Design, Construction, and Materials 11-4
of Construction
11.4 Control of Incoming Waste 11-5
11.5 Monitoring the Performance of the Waste Containment unit.. 11-6
11.5.1 Leak Detection by a Secondary Leachate 11-6
Collection and Removal System (LCRS)
11.5.2 Areal Techniques 11-8
11.5.2.1 Monitoring Wells 11-8
11.5.2.2 Electrical Conductivity Surveys 11-12
11.5.3 Point Source Leak-Detection Techniques 11-14
11.6 Monitoring the Components of a Lining System for a waste 11-18
Containment Unit and Related Maintenance Activities
xxx
-------
11.6.1 Monitoring an In-
11.6.2 Monitoring, Maint
Collection and Removal
11.6.3 Monitoring the G
11.6.4 Monitoring the Ea
11.6.5 Vegetation Control
11.6.6 Rodent Control
11.6.7 Monitoring of Di
11.6.8 Monitoring to
Unauthorized Dump
11.7 Maintenance of the Final
11.8 References
version Drainage System
Prevent Vandalism and
CHAPTER 12. COSTS ASSOCIATED WITH
OF WASTE STORAGE AND DISPOSAL
MATERIALS AND CONSTRUCTION
UNITS
12.1 Introduction
12.2 Factors Affecting Costs o
12.3 Liner System Component Co
12.3.1 Factors Influenci
12.3.2 Flexible Membrane
12.3.3 Geotextiles
12.3.4 Drainage Material
12.3.5 Geogrids
12.3.6 Piping
12.4 Installation Costs of Li
12.5 Construction Costs for Ea
12.6 Costs for Leachate Collec
12.7 Costs for a One-Acre Doub
Service Liner
enance, and Repair of Leachate
Systems
s-Venting System
rthworks
ing
Cover
f Waste Containment Units
sts
ng Component Costs
Liners
ners
thworks
tion and Removal Systems
e-Lined Surface Impoundment
xxxi
11-18
11-21
11-22
11-22
11-22
11-23
11-23
11-23
11-23
11-25
12-1
12-1
12-4
12-4
12-4
12-5
12-5
12-7
12-9
12-9
12-10
12-11
12-12
-------
12.8 Costs for Admix and Sprayed-On Liners 12-16
12.9 Comparison of Costs of Alternate Land Waste
Disposal Technologies 12-17
12.10 Costs of Quality Assurance 12-17
12.11 References 12-21
APPENDIXES
A SIGNIFICANT WASTE SOURCES AND TYPES OF WASTE A-l
B REPRESENTATIVE LIST OF ORGANIZATIONS IN THE FML INDUSTRY B-l
C POLYMERS FORMERLY USED IN MANUFACTURE OF FMLS C-l
D POUCH TEST FOR PERMEABILITY OF POLYMERIC FMLS D-l
E PROCEDURE FOR DETERMINATION OF THE EXTRACTABLES CONTENT E-l
OF EXPOSED AND UNEXPOSED FMLS
F PROPERTIES OF UNEXPOSED POLYMERIC FMLS AND OTHER F-l
COMMERCIAL SHEETINGS
G PROCEDURE FOR DETERMINATION OF THE VOLATILES OF EXPOSED G-l
AND UNEXPOSED FMLS
H TUB TEST OF POLYMERIC FMLS H-l
I DESIGN OF THE PIPE NETWORK FOR LEACHATE COLLECTION 1-1
SYSTEMS
J ANALYSES OF HAZARDOUS WASTES USED IN EXPOSURES REPORTED J-l
BY HAXO
K SELECTED PROPERTY STANDARDS FOR REPRESENTATIVE K-l
FMLS AVAILABLE IN JULY 1988
L METHOD 9090 COMPATIBILITY TEST FOR WASTES AND MEMBRANE L-l
LINERS
M OBSERVATIONS AND TESTS FOR THE CONSTRUCTION QUALITY M-l
ASSURANCE AND QUALITY CONTROL OF HAZARDOUS WASTE
DISPOSAL FACILITIES
N LOCUS-OF-BREAK CODES FOR VARIOUS TYPES OF FML SEAMS N-l
xxxn
-------
:IGURES
Figure
2-1
2-2
2-3
3-1
3-2
3-3
3-4
4-1
4-2
4-3
4-4
4-5
4-6
Two conditions that FMLs in contact with waste liquids can
encounter in waste containnent units.
Sources of leachate genera
Generalized composition of
,ed by a solid waste.
leachates and other waste liquids
that may contact a liner iiji service.
Flow pattern of liquid through a soil on macroscopic and
microscopic scale.
Darcy's experiment.
Schematic representation o
chemical potential and concentration with distance
through the thickness of a
steady state.
Comparison of leachate levels in a leachate collection
sump to atmospheric pressure.
Distribution of molecular v\
Schematics of polymers structures.
Models of viscoelastic materials showing different
arrangements of spring and
Strain response or creep of
model of a viscoelastic po
stress.
the variation of permeant
membrane permeation in the
eights in a high polymer.
dashpots,
the combination four-parameter
ymeric compound to an applied
Basic structure of the polymeric FML industry from raw
material producers to liner
Relationship among crystall
mechanical properties of polyethylene.
installers.
inity, molecular weight, and
Page
2-2
2-4
2-7
3-5
3-6
3-9
3-13
4-6
4-7
4-8
4-10
4-17
4-22
ixiii
-------
4-7 Schematic comparison of the structures of PE and ethylene 4-23
copolymers of different densities.
4-8 Various types of polymeric FMLs available for lining 4-27
applications.
4-9 Roll configuration of calenders: (a) three-roll calenders, 4-28
and (b) four-roll calenders.
4-10 Nylon-reinforced, butyl lining samples showing different 4-30
weaves and weights of nylon.
4-11 Extrusion of polyethylene FML using an extruder with a 4-31
circular die.
4-12 Configurations of seams used in joining FML sheets and 4-35
panels and method of seaming.
4-13 Gas permeability apparatus in ASTM D1434, Procedure V - 4-42
Volumetric.
4-14 Permeability of ELPO to C02, CH4, and N2 as a function 4-45
of temperature.
4-15 Exploded view of water vapor transmission cup. 4-46
4-16 Exploded view of SVT cup with aluminum sealing rings. 4-49
4-17 Weight changes of HOPE-A pouches filled with xylene 4-53
immersed in xylene or DI water.
4-18 Weight changes of HDPE-A pouches filled with acetone or 4-54
50:50 acetone:DI water immersed in acetone or DI water.
4-19 Weight changes of PVC pouches containing 5 and 10% aqueous 4-58
solutions of LiCl during immersion in DI water.
4-20 Transmission rates of various hydrocarbons as a function of 4-60
the reciprocal of the thickness of HOPE FMLs.
4-21 Gas transmission rate of methane at 23°C through HOPE vs 4-61
reciprocal of FML thickness.
4-22 Tensile at yield and elongation at yield of five HOPE FMLs 4-65
of 30 to 100 mil thickness tested at 23° to 80°C.
4-23 Modulus of elasticity and elongation at break of five HOPE 4-66
FMLs of 30 to 100 mil thickness tested at 23° to 80°C.
xxxiv
-------
4-24 Force at puncture (FTMS 101C, Method 2065) vs speed of 4-69
deformation of two unreinforced FMLs.
4-25 Force at puncture (FTMS 101C, Method 2065) vs speed of 4-69
test for two different thicknesses of HOPE FML.
4-26 Force at puncture (FTMS 101C, Method 2065) vs thickness 4-70
of test specimen.
4-27 Effect of lubricating the probe on puncture resistance of 4-72
40-mil HOPE FML (No. 419) at different speeds of test.
4-28 Pressure vessel device for three-dimensional stress-strain 4-72
tests.
4-29 Results of three-dimensional stress-strain testing of nine 4-74
FMLs.
4-30 Relationship between thickness of FML and pressure and 4-75
strain failure for three different FMLs of the same
composition.
4-31 Determination of grain or machine direction. 4-92
4-32 Gas chromatographic determination of the diethylhexyl 4-95
phthalate content in an extract of a PVC FML.
4-33 Infrared scan of a dried film from an n-hexane extract 4-97
from an HOPE FML.
4-34 TGA of an unexposed black HOPE FML. 4-99
4-35 TGA of an unexposed EPDM FML. 4-100
4-36 TGA of an exposed plasticized PVC FML. 4-102
4-37 DSC determination of the melting point and PE crystal- 4-103
linity in an HOPE FML.
4-38 Crystallinity of NBS Standard Polyethylene 1475 as a 4-105
function of cooling rate.
4-39 Puncture assembly for the tetrahedral tip probe, FTMS 101C, 4-112
Method 2031.
4-40 Jig for puncture resistance and elongation test, FTMS 101C, 4-113
Method 2065.
4-41 Schematic of hydrostatic resistance test machine (ASTM 751, 4-114
Method A).
xxxv
-------
4-42 Seam strength specimen for testing seams of fabric- 4-116
reinforced FMLs in accordance with ASTM D751, modified.
4-43 Two configurations of peel testing. 4-117
4-44 Specimen and equipment of ASTM D1693 for bent-strip 4-120
test specimen.
4-45 Schematic view of constant-load stress rupture test of 4-121
ASTM D2552.
4-46 Schematic of a proposed test method for determining 4-122
environmental stress-cracking resistance.
4-47 Confined and unconfined stress-strain testing of two 4-127
geotextiles.
4-48 Types of creep behavior. 4-128
4-49 Confined and unconfined stress-strain testing followed 4-129
by creep of two geosynthetics.
4-50 Direct shear test to evaluate FML-against-soil shear 4-130
strength.
4-51 Typical direct shear curves and determination of FML- 4-131
to-soil friction angle and adhesion.
4-52 Schematic view of embedment depth test apparatus. 4-134
4-53 Curve representing the relationship between applied 4-134
normal pressure and depth within the channels in
embedment depth test.
4-54 Schematic of hydrostatic test facility. 4-136
4-55 Plan for the analysis of exposed polymeric FMLs. 4-138
4-56 Various types of geotextiles. 4-141
4-57 Various types of reinforcement geogrids. 4-146
4-58 Various types of drainage geonets. 4-149
4-59 Flow rate behavior of geonets at different gradients. 4-153
4-60 The intrusion of FMLs into geonets. 4-155
4-61 Various types of drainage geocomposites. 4-156
4-62 Flow rate behavior of geocomposite cores between rigid 4-159
plates in short-term test.
xxxvi
-------
4-63 Sequence of photographs showing the intrusion of a filter 4-160
geotextile into drainage core flow space of a drainage
composite with high columns when under various loads.
4-64 Sequence of photographs showing the intrusion of a filter 4-161
geotextile into drainage core flow space of a drainage
composite with extruded cuspations when under various
loads for short periods of time.
5-1 Schematic of a closed landfill. 5-6
5-2 Schematic of a lined MSW landfill. 5-7
5-3 Environmental conditions encountered by an uncovered FML. 5-9
5-4 Schematic of an FML/composite double-liner system. 5-13
5-5 Schematic of an FML/composite double-liner system. 5-13
5-6 Schematic profile of FML/composite double-liner system for 5-14
a hazardous waste landfill presenting EPA draft guidance.
5-7 Typical gypsum stack design. 5-15
5-8 Conceptual flow diagram of typical heap leach operation. 5-16
5-9 FML used for secondary containment. 5-17
5-10 Schematic showing stresses in an FML. 5-21
5-11 Landfill simulator used to evaluate FMLs specimen. 5-24
5-12 Base of the landfill simulator in which the FMLs were 5-24
exposed.
5-13 Average solids content of the leachates produced in the 5-27
MSW simulators, November 1974 through July 1979.
5-14 Average TVA, as acetic acid, of the leachates produced in 5-27
the MSW simulators, November 1974 through July 1979.
5-15 Design of cells for long-term exposure of FMLs. 5-34
5-16 FML test specimens for long-term exposure in one-sided 5-34
exposure cells.
5-17 Unassembled exposure cell used for FML specimens. 5-45
5-18 Two photographs of the recovered neoprene FML (No. 43). 5-49
5-19 Drawing of exposed ELPO liner showing locations where the 5-53
test specimens were cut.
XXXV11
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5-20 Thickness of strip of exposed ELPO liner. 5-54
5-21 Retention of tensile strength of ELPO exposed in the oily 5-56
waste.
5-22 Schematic of accelerated aging column. 5-60
5-23 Pouch assembly showing the movement of constituents during 5-62
the pouch test.
5-24 Monitoring data for ELPO pouches (P30A and P30B) containing 5-69
the highly alkaline waste.
5-25 Permeation rates of 0.05 weight percent aqueous solutions of 5-76
toluene through various FMLs.
5-26 Permeation rates of concentrated and dilute solutions of 5-76
various organics through a 1-mm (40-mil) HOPE FML.
5-27 Schematic of the three-compartment test apparatus. 5-77
5-28 Schematic of HOPE immersion tank. 5-83
5-29 Retention of FML tensile strength as a function of immersion 5-87
time in MSW leachate—Butyl rubber, CPE, CSPE, ELPO, and
EPDM FMLs.
5-30 Retention of FML tensile strength as a function of immersion 5-88
time in MSW leachate--EPDM, neoprene, PB, PEL, LDPE, PVC,
and PVC-pitch FMLs.
5-31 Relationship of changes in physical properties to furfural 5-111
concentration at 23°C for PVC.
5-32 Change in weight of a PVC immersed in furfural and MEK 5-117
aqueous solutions as a function of time.
5-33 Schematic of the exposure tank used in the FML compati- 5-123
bility studies with spiked leachate and water.
5-34 Reduction in concentration of TCE in a dilute aqueous 5-128
solution.
5-35 Reduction in concentration of toluene in a dilute aqueous 5-129
solution.
5-36 Loss of organics from HOPE FML samples saturated with 5-130
different organics.
5-37 Detailed section through a hydrostatic testing vessel. 5-132
xxxvm
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5-38 Schematic diagram of a permeameter modified to apply 5-137
overburden pressure.
5-39 Flow patterns under the extreme conditions below a hole in 5-138
an FML.
5-40 Hydraulic transmissivity testing device. 5-140
5-41 Transmissivity response versus applied normal stress 5-142
for various needled nonwoven geotextiles.
5-42 Results of transmissivity tests at 20°C on nets DN1, DN2, 5-144
and DNS.
5-43 In-plane flow rate tests of a 0.25-in. thick geonet under 5-145
different boundary conditions.
5-44 Rack loaded for exposing FML specimens. The rack was 5-148
exposed at a 45° angle to the south.
5-45 Design of cells for long-term exposure of admix liners 5-157
to different hazardous wastes.
6-1 Lagoon lay-out showing grid pattern used in sampling 6-25
6-2 Cross section of the lagoon from the northwest to 6-28
southwest corners.
6-3 Plan view of lagoon containing a calcium sulfate sludge 6-34
showing sampling locations.
6-4 Idealized cross section of lagoon showing sample 6-35
locations.
6-5 Schematic drawing of the basin showing the locations 6-46
where the FML samples were collected.
6-6 Tensile at break of the samples of exposed FMLs as a 6-52
function of their extractables.
6-7 Stress at 100% elongation of the samples of exposed 6-52
FMLs as a function of their extractables.
6-8 Puncture resistance of the samples of exposed FMLs as a 6-53
function of their extractables.
6-9 Elongation at break of the samples of exposed FMLs as a 6-53
function of their extractables.
6-10 Typical cross section of the dikes for the uranium tailings 6-58
ponds—Ponds 1-9.
xxxvix
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6-11 Plasticizer loss as a function of time for samples 6-59
permanently exposed.
6-12 Study of the influence of immersion on aging. 6-60
6-13 Plasticizer loss as a function of location on the slope 6-60
of Pond 5.
6-14 Retention of elongation at break as a function of the 6-61
plasticizer loss.
6-15 Typical cross section of the dike for a uranium-tailings 6-63
pond—Pond 10.
6-16 Schematic showing FML with a seam being lifted off 6-64
its support.
6-17 Schematic showing stresses on seams with excessive flaps. 6-65
6-18 Geotextile permeameter. 6-78
7-1 An excavated surface impoundment. 7-3
7-2 Diked surface impoundment constructed above-grade. 7-4
7-3 Diked surface impoundment partially excavated below 7-5
grade.
7-4 A cross-valley surface impoundment configuration. 7-5
7-5 Percolation through a closed MSW landfill and movement 7-11
of the leachate into the soil environment.
7-6 Schematic profile of an FML/composite double liner 7-24
system presenting EPA draft guidance.
7-7 Cover system design recommended by EPA guidance. 7-27
7-8 Methods of liner and sidewall compaction. 7-34
7-9 Schematic of homogeneous and zoned embankments for surface 7-35
impoundments lined with FML/composite double liners.
7-10 Various geotextile or geogrid deployment schemes for 7-38
stabilizing embankments.
7-11 Design approach toward soil slope reinforcement using 7-39
geogrids and geotextiles.
xl
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7-12 Types of clay particle arrangements. 7-44
7-13 Compaction response of clay soils. 7-46
7-14 Water content range for achieving a density value related 7-47
to compaction response of a soil.
7-15 Relationship between hydraulic conductivity and the void 7-48
ratio for two soils.
7-16 Schematic representation for Case 1 of the relationships 7-50
between soil dry density, soil moisture content, and
permeability coefficient.
7-17 Schematic representation for Case 2 of the relationships 7-51
between soil dry density, soil moisture content, and
permeability coefficient.
7-18 FML sheet layout for a surface impoundment. 7-63
7-19 An FML panel layout. 7-63
7-20 Schematic of granular drainage systems in secondary LCRSs 7-72
for double-lined surface impoundments.
7-21 Schematic of an LCRS for a surface impoundment with a 7-74
synthetic drainage layer.
7-22 Schematic showing the use of synthetic drainage material 7-75
on side slopes.
7-23 Schematic layout of pipe in a secondary LCRS for a surface 7-76
impoundment.
7-24A Schematic of a sump system—Floor of the unit and partway 7-78
up the slope.
7-24B Schematic of a sump system—Detail showing trench for 7-79
riser pipe on the slopes.
7-24C Schematic of a sump system—Berm of the unit. 7-80
7-25 Schematic of a monitoring and collection manhole 7-81
located outside a unit.
7-26 Schematic of an auxiliary cleanout. 7-82
7-27 Schematic of a double composite liner system. 7-85
xli
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7-28 Schematic of a low-volume sump for a primary LCRS. 7-89
7-29 Schematic of a high-volume sump for a primary LCRS. 7-90
7-30 Plan view of a high-volume sump for a primary LCRS. 7-91
7-31 Schematic presenting different methods of anchoring 7-93
FMLs.
7-32 Example of a flange seal around a penetration. 7-94
7-33 Example of a seal around a penetration using the 7-95
boot-type method.
7-34 Two views of a gas vent design for a single-lined 7-97
surface impoundment.
7-35 A gas vent design for a single-lined surface 7-98
impoundment.
7-36 Schematic of a double-lined surface impoundment with 7-98
a gas-venting system underneath the lining system.
7-37 Splash pad construction using a concrete subbase. 7-99
7-38 Sluice-type trough constructed of FML. 7-100
7-39 Typical design details for floating and fixed 7-101
aeration systems.
7-40 Schematic profile of a closed landfill. 7-105
7-41 Schematic of a gas-venting pipe system for a 7-106
landfill cover.
9-1 Typical earthwork equipment used during impoundment 9-3
construction.
9-2 Trenching machine for anchor trenches; dozer and 9-4
earth mover for berm construction.
9-3 Conveyor system used during earthwork construction. 9-5
9-4 Schematic representation of the compactive behavior of 9-6
soils.
9-5 Equipment for compaction and fine finishing. 9-9
9-6 Water tank vehicle used to prepare the soil for compaction. 9-10
xlii
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9-7 Schematic of a test fill. 9-12
9-8 Photographs showing various stages of subgrade finishing. 9-15
9-9 Scraper and roller being used to fine finish a subgrade. 9-16
9-10 Representative subgrade surface texture. 9-16
9-11 Salt grass penetrating a 30-mil FML. 9-17
9-12 FML panels are shipped to the site on wooden pallets. 9-18
9-13 Damage to a fabric-reinforced FML caused by "blocking." 9-19
9-14 HOPE FMLs are shipped to the site rolled onto drums. 9-21
9-15 Use of sandbags to anchor unseamed sheets and unseamed 9-22
edges of FMLs to prevent wind damage.
9-16 Hand-held extrusion welders for seaming HOPE FMLs. 9-23
9-17 A partially-automated extrusion welder for seaming 9-24
HOPE FMLs.
9-18 Schematic of hot-wedge welding device for seaming 9-25
PE FMLs.
9-19 Field seaming operation using bodied-solvent adhesive. 9-25
9-20 Heat guns being used to facilitate field seaming of FMLs. 9-27
9-21 The instructions for unrolling FML panels are shown 9-30
on each container.
9-22 Panels of a fabric-reinforced FML being unfolded or 9-31
unrolled.
9-23 Workmen "pulling" a panel fabricated from a fabric- 9-32
reinforced FML across a subgrade.
9-24 Spotting a panel fabricated from a fabric-reinforced FML. 9-33
9-25 Pulling an FML panel smooth. 9-34
9-26 Typical lap seams for fabric-reinforced thermoplastic FMLs. 9-38
9-27 Inspecting overlap between panels of a fabric-reinforced 9-39
FML.
xliii
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9-28 Cleaning the surface of a fabric-reinforced FML prior 9-40
to seaming.
9-29 Seaming crews working with solvents are advised to wear 9-41
gloves.
9-30 Field seaming of a fabric-reinforced thermoplastic FML. 9-42
9-31 Rolling the seam of a fabric-reinforced thermoplastic FML. 9-43
9-32 Parallel and perpendicular buffing of an HOPE FML. 9-44
9-33 Repairing a wrinkle in the seam of a fabric-reinforced 9-45
thermoplastic FML.
9-34 Testing the continuity of HOPE FML seams. 9-47
9-35 Schematic of sequential procedure for wrapping an LCRS 9-50
trench with a geotextile.
9-36 Schematic of a cover system showing the various layers. 9-53
9-37 Construction of a final cover system in areal increments. 9-54
9-38 A 2-in. thick asphalt concrete liner being applied. 9-56
9-39 Steps in the installation of a soil-cement liner. 9-58
9-40 Placement of sprayed-on liners. 9-61
11-1 Construction details for a sample monitoring well. 11-9
11-2 Multilevel sampling wells installed in individual, small- 11-10
diameter boreholes.
11-3 Illustration showing a disadvantage of using a single 11-11
monitoring well.
11-4 Pressure-vacuum lysimeter is installed in a borehole 11-12
for collection of water samples.
11-5 Two-coil electromagnetic induction apparatus. 11-13
11-6 Schematic of single channel AEM equipment. 11-15
11-7 Schematic showing installation of an AEM sensor. 11-15
11-8 Schematic of a TDR system. 11-16
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11-9 Schematic of the electrical resistivity testing technique 11-17
for detecting and locating leaks in an FML system.
11-10 Schematic for a coupon in a landfill. 11-19
11-11 Schematic for a coupon in a waste pile. 11-19
11-12 Schematic for coupon options in a surface impoundment. 11-19
12-1 Configuration of a granular drainage system for a 12-14
secondary leachate collection system.
12-2 Comparison of the costs of four disposal technologies. 12-19
D-l Die for special dumbbell. D-6
D-2 Pattern for cutting pieces of membrane for making D-6
the pouch.
D-3 Schematic of pouch assembly. D-7
D-4 Pouch and auxiliary equipment for determining perme- D-7
ability of polymeric FMLs.
D-5 Suggested pattern for cutting test specimens out of D-9
the exposed pouch.
F-l Die for special dumbbell. F-6
G-l Machine direction determination. G-3
H-l Tub used in the outdoor exposure of polymeric FMLs in H-3
contact with wastes.
H-2 The open exposure tubs lined with polymeric FMLs and H-4
partially filled with waste liquids.
H-3 Die for special dumbbell. H-7
H-4 Drawing of an exposed liner showing locations where the H-10
test specimens were cut and the directional orientation
in which the liner was exposed.
1-1 Determination of leachate head on FML liners using 1-3
flow net solution.
1-2 Required capacity of leachate collection pipe. 1-4
1-3 Sizing of leachate collection pipe. 1-5
xlv
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1-4 Pipe installation—conditions and loading. 1-6
1-5 Trench condition—pipe load coefficient Cvs. 1-8
1-6 Trench condition—pipe load coefficient C^. 1-9
1-7 Selection of pipe strength. 1-12
1-8 Typical leachate collection drains. 1-15
L-l Suggested pattern for cutting test specimens from L-6
nonreinforced crosslinked or thermoplastic immersed
liner samples.
L-2 Suggested pattern for cutting test specimens from 1-7
fabric reinforced immersed samples.
L-3 Suggested pattern for cutting test specimens from L-8
semi crystal line immersed liner samples.
L-4 Die for tensile dumbbell (nonreinforced liners). L-9
N-l Locus-of-break codes for dielectric-welded or N-2
solvent-welded seams in unreinforced FMLs tested for
seam strength in shear and peel modes.
N-2 Locus-of-break codes for seams in three-ply N-3
fabric-reinforced FMLs tested for seam strength
in shear and peel modes.
N-3 Locus-of-break codes for fillet-extrusion weld seams N-4
in semi crystal line FMLs tested for seam strength in
shear and peel modes.
N-4 Locus-of-break codes for extrusion weld seams in N-5
semicrystalline FMLs tested for seam strength in
shear and peel modes.
N-5 Locus-of-break codes for dual hot-wedge seams in N-6
semicrystalline FMLs tested for seam strength in
shear and peel modes.
xlvi
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TABLES
Table Page
2-1 Types of Waste Liquids in Surface Impoundments. 2-5
2-2 Methods Used for Analyze Leachate Samples. 2-10
2-3 Statistical Data for Metals, pH, Eh, Conductivity, 2-11
Total Cyanide, TOC, and COD.
2-4 Percent of TOC Content Accounted for by Analysis 2-12
for Pollutants.
2-5 Initial Characterization of a Hazardous Waste 2-13
Leachate.
2-6 Total Organic Carbon Content Identified by 2-14
chemical Classification.
2-7 Facility A Ash Analytical Data - Organics. 2-19
2-8 Facility A Ash Analytical Data - Metals. 2-20
2-9 Facility B Ash Analytical Data - Metals. 2-21
2-10 Predominant Types of Organic Chemicals Stored 2-25
in Underground Storage Tanks.
4-1 Materials Used in the Construction of Liner and 4-1
Leachate Control Systems.
4-2 Polymers Used in the Manufacture of Major Products 4-5
for the Construction of Waste Management Facilities.
4-3 Comparison of the Coefficient of Linear Thermal 4-11
Expansion of Polymeric Compositions.
4-4 Polymers Used in Manufacture of FMLs. 4-18
4-5 Basic Compositions of Polymeric FML Compounds. 4-26
xlvii
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4-6 Bonding Systems Available for Seaming Polymeric FMLs 4-34
in Factory and Field.
4-7 Permeability of Polymeric FMLs to Gases at 23°C, Determined 4-44
in Accordance with ASTM D1434, Procedure V.
4-8 Permeability of Polymeric FMLs to Water Vapor. 4-47
4-9 Permeability of Polymeric FMLs to Various Solvents, Measured 4-51
in Accordance with ASTM E96, Procedure BW (Modified).
4-10 Organic Dyes Used as Tracers in Pouch Experiments. 4-52
4-11 Transmission Rates of Acetone and Xylene Through FMLs 4-56
Obtained by the Pouch Test Compared with SVT and MVT.
4-12 Water-Soluble Tracer Dyes Used in Pouch Experiments. 4-57
4-13 Combinations of Aqueous Test Liquids Containing Water- 4-57
Soluble Tracers and FMLs in Pouch Experiments.
4-14 Properties of HOPE FMLs of Various Nominal Thicknesses 4-64
at Different Temperatures.
4-15 Properties of Thermoplastic FMLs at Different Temperatures. 4-67
4-16 The Effect of Lubricating the Tip of the Probe with SAE 4-71
30 Oil and Castor Oil on the Puncture Reistance of two
HOPE FMLs.
4-17 Combined Effects of Lubrication of the Probe and the Speed 4-73
of Deformation on Puncture Resistance of a 40-mil HOPE FML.
4-18 Solubility Parameter Values for FMLs and Other Polymeric 4-80
Compositions.
4-19 Potential Degradation Processes in Polymeric FMLs 4-82
During Service.
4-20 Environmental Factors Affecting Durability and Service 4-84
Life.
4-21 Appropriate or Applicable Methods for Testing Analytical 4-89
Properties of Polymeric FMLs.
4-22 Analysis of Unexposed Polymeric FMLs. 4-90
4-23 Thermogravimetric Analysis of Unexposed Polymeric FMLs. 4-101
4-24 Percent Crystallinity and Melting Temperature of NBS 4-104
Standard Polyethylene 1475 with Varying Thermal History.
xlviii
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4-25 Differential Scanning Calorimetry of Selected Polyethylenes. 4-106
4-26 Appropriate or Applicable Methods for Testing the Physical 4-108
Properties of Polymeric FMLs.
4-27 Appropriate or Applicable Methods for Determining Effects 4-119
of Environmental or Accelerated Exposures on Polymeric FMLs.
4-28 Friction Angle Values and Efficiencies for FMLs to 4-132
Granular Soils.
4-29 Shear Strength Parameters of FMLs to Cohesive Soils at 4-133
Optimum Water Content.
4-30 Comparison of the Fingerprints of Samples of Two 4-139
Polyethylene FMLs.
4-31 General Comments on Polymers Used in Manufacture of 4-142
Geotextiles.
4-32 Typical Permittivity and Permeability Values of 4-143
Geotextiles.
4-33 Currently Available Geogrids. 4-147
4-34 Available Geonets for Drainage Purposes. 4-151
4-35 Various Types of Drainage Geocomposites. 4-158
4-36 Plastic Pipe Appropriate for Use in Leachate Collection 4-162
and Leak-Detection Systems.
4-37 Methods for Evaluating HOPE Pipe. 4-164
4-38 Permeability of Asphalt Concrete to Water. 4-166
4-39 Applicable Methods for Testing of Hydraulic Asphalt 4-168
Concrete.
4-40 Water Permeability of Soil-Cement Specimens. 4-171
4-41 Applicable Test Methods for Analysis of Soil-Cement 4-172
Liner Materials.
5-1 Environmental Conditions Encountered by FMLs and Ancil- 5-4
lary Materials Prior to and During Construction of Waste
Storage and Disposal Facilities.
5-2 Environmental Conditions Encountered by Liners Systems 5-8
During Service in an MSW Landfill.
xlix
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5-3 Environmental Conditions Potentially Encountered by Poly- 5-10
meric FMLs in Weather Exposure in Surface Impoundments.
5-4 Environmental Conditions Potentially Encountered by Poly- 5-11
meric FMLs at the Air-Waste Liquid Interface in Surface
Impoundments.
5-5 Environmental Conditions Potentially Encountered by Poly- 5-12
meric FMLs and Other Materials of Construction in Exposure
to Waste Liquids and Leachates in Surface Impoundments.
5-6 Testing of Polymeric FMLs. 5-26
5-7 Analysis of Leachate from MSW Simulator. 5-26
5-8 Effect on Properties of Polymeric FMLs After 12 and 56 5-28
Months of Exposure to Leachate in MSW Landfill Simulator.
5-9 Comparison of Water and MSW Leachate Absorptions by Poly- 5-33
meric FMLs in One Year at Room Temperature.
5-10 Combinations of Polymeric FMLs and Hazardous Wastes Tested 5-35
in One-Sided Exposure Cells.
5-11 Testing of Polymeric FMLs Exposed to Hazardous Wastes. 5-36
5-12 Exposure of Polymeric FMLs to Hazardous Wastes in One- 5-37
Sided Exposure Cells - Days of Exposure.
5-13 Exposure of Polymeric FMLs to Hazardous Wastes in One- 5-38
Sided Exposure Cells - Percent Volatiles.
5-14 Exposure of Polymeric FMLs to Hazardous Wastes in One- 5-39
Sided Exposure Cells - Percent Extractables.
5-15 Exposure of Polymeric FMLs to Hazardous Wastes in One- 5-40
Sided Exposure Cells - Percent Retention of Elongation
at Break.
5-16 Exposure of Polymeric FMLs to Hazardous Wastes in One- 5-41
Sided Exposure Cells - Percent Retention of Stress
at 100% Elongation.
5-17 Seams in Polymeric FML Samples Exposed to Hazardous 5-42
Wastes in One-Sided Exposure Cells.
5-18 Exposure of Polymeric FMLs to Hazardous Wastes in One- 5-43
Sided Exposure Cells - Effect on Seam Strength Measured
in Shear Mode.
-------
5-19 Exposure of Polymeric FMLs to Hazardous Wastes in One- 5-44
Sided Exposure Cells - Effect on Seam Strength Measured
in Peel Mode.
5-20 Combinations of Polymeric FMLs and Wastes Removed from 5-52
Exposure Tub Test and Exposure Times in Days.
5-21 Properties of Second ELPO Liner Exposed to an Oily Waste 5-55
("Oil Pond 104") for 1308 Days in Tub on Laboratory Roof
in Oakland, CA.
5-22 Properties of a Neoprene FML Exposed to an Oily Waste 5-57
("Oil Pond 104") for 2008 Days in Tub on Laboratory
Roof in Oakland, CA.
5-23 Seam Strength of Neoprene 82 FML Sample After 2008 Days 5-58
of Exposure in Tub Containing Oily Waste, "Oil Pond 104".
5-24 Summary of the Results of the Roof Tub Exposures. 5-59
5-25 Results of DSC Analyses of Virgin and Aged HOPE FML 5-61
Samples.
5-26 Characteristics of Leachate in Pouches. 5-62
5-27 Tests of FML Pouches Filled With MSW Leachate. 5-63
5-28 Pouch Tests of Polymeric FMLs with Different Waste 5-65
Liquids—Exposure Time in Days.
5-29 Pouch Tests of Polymeric FMLs With Different Waste Liquids. 5-66
Electrical Conductivity (in ymho/cm) of Outer Water at
Conclusion of Test or Before Leakage from Pouch.
5-30 Pouch Tests of Polymeric FMLs With Different Waste 5-67
Liquids—Weight Change (in Grams) of the Waste Liquid in
the Pouches as Measured After Pouches were Dismantled.
5-31 Measurements on the Two ELPOa Pouches Filled with "Slop 5-70
Water" Waste (W-4).
5-32 Permeation Rates of the Components of a Mixture of Organics 5-73
Through a 40-Mil HOPE FML.
5-33 Transmission of Solvent Mixtures Through a 20-Mil ELPO 5-74
FML.
5-34 Zones in Three-Compartment Test Apparatus. 5-78
5-35 Organics Used in Three-Compartment Apparatus Experiment 5-79
with Dilute Aqueous Solutions.
li
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5-36 Selected Property Values of a 33-Mil LLDPE FML (Matrecon 5-80
FML No. 284).
5-37 Distribution of Organics in Three-Compartment Test 5-81
Apparatus Separated by Polyethylene FMLs.
5-38 Analysis of Leachate Used in the Immersion System. 5-84
5-39 Summary of the Effects of Immersion of Polymeric FMLs in 5-86
MSW Leachate for 8, 19, and 31 Months.
5-40 Retention of Modulus of Polymeric FMLs on Immersion in MSW 5-89
Leachate.
5-41 Wastes and Test Liquids in Immersion Tests. 5-90
5-42 Exposure of FML Specimens in Immersion Test to Various 5-92
Hazardous Wastes - Number of Days of Immersion.
5-43 Exposure of FML Specimens in Immersion Test to Various 5-93
Hazardous Wastes - Percent Increase in Weight.
5-44 Exposure of FML Specimens in Immersion Test to Various 5-94
Hazardous Wastes - Retention of Stress at 100% Elongation.
5-45 Analyses of CPE and PVC FMLs Exposed in Saturated 5-96
Solution.
5-46 Polymeric Compositions in Swelling Tests to Determine 5-100
Equilibrium Swelling.
5-47 Organics Used in the Equilibrium Swelling Tests by 5-101
Type or Class.
5-48 Properties of the Organics Used in FML Equilibrium 5-102
Swelling and Solubility Parameter Study.
5-49 Equilibrium Volume Swelling of the CPE and CSPE 5-104
Specimens Immersed in 30 Organics and in Water.
5-50 Equilibrium Volume Swelling of the ECO, EPDM, EVA, CR, 5-105
Nitrile Rubber (NBR), PEL, and PB Specimens Immersed
in 30 Organics and in Water.
5-51 Equilibrium Volume Swelling of the LDPE, LLDPE, HOPE, 5-106
HDPE-A, PU, PVC, PVC-E, and PVC-OR Specimens Immersed
in 30 Organics and in Water.
5-52 Unreinforced FMLs Selected for Chemical Resistance 5-107
Testing.
Ill
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5-53 Chemical Liquids Selected for FML Immersion Tests. 5-108
5-54 Testing of Samples in Immersion Tests. 5-110
5-55 Seaming Procedures Used to Prepare Samples for Immersion 5-114
in Test Solutions.
5-56 Change in Weight of FMLs Exposed to Various Test Liquids for 5-116
52 Weeks.
5-57 Performance of FML Seam Samples Exposed to Various Test 5-118
Liquids.
5-58 GC Analysis of the Exposed FML Samples. 5-126
5-59 Evaporation of Volatile Organics from Aqueous Solutions. 5-129
5-60 Hydrostatic Resistance of Three PVC FMLs over Three 5-133
Different Subgrades.
5-61 Hydrostatic Puncture Resistance Testing of HOPE FMLs and 5-135
LLDPE FMLs with and without Geotextiles Over Varying
Pyramid Protrusions.
5-62 Typical Values of Drainage Capability (In-Plane Flow) of 5-141
Geotextiles.
5-63 Effect of Exposure on Roof of Laboratory in Oakland, 5-150
California, on Properties of Polymeric FMLs-- Butyl, CPE,
CSPE, ELPO, and EPDM.
5-64 Effect of Exposure on Roof of Laboratory in Oakland, 5-151
California, on Properties of Polymeric FMLs--Neoprene,
Polyester Elastomer, and PVC.
5-65 Ratings in Visual Inspections of Selected Samples Exposed 5-153
to EMMAQUA Conditions.
5-66 Unconfined Compressive Strength of Admixed Liner Specimens 5-155
Before and After Exposure to Water and to MSW Leachate.
5-67 Permeability of Soil-Cement Samples Before and After 5-156
Exposure to MSW Leachate.
5-68 Properties of Asphalt in Sprayed-on FMLs After 12, 43, and 5-159
56 Months of Exposure to MSW Leachate.
5-69 Effect of Exposure to Hazardous Wastes on an Emulsified 5-161
Asphalt Sprayed-on Nonwoven Fabric.
1111
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6-1 Potential Factors that Could Contribute to the Formation 6-9
of Breaches in an FML in Service in a Waste Containment
Unit.
6-2 Summary of FML Field Studies Performed by Matrecon. 6-16
6-3 Methods Used in Testing FML Samples Recovered During 6-17
Case Studies Conducted by Matrecon.
6-4 Properties of 30-Mil Polyvinyl Chloride FML Recovered 6-18
from a Demonstration Landfill in Crawford County, OH
6-5 Properties of 15-Mil PVC FML Exposed at a Sludge Lagoon 6-19
in the Northeast for 6.5 Years.
6-6 Effects on CSPE, LDPE, and CPE FMLs of Exposure in MSW 6-21
Cells at Boone County Field Site for 9 Years.
6-7 Exposure of CSPE FML Without Fabric Reinforcement in 6-23
Pilot-Scale MSW Landfill Cells at Georgia Institute of
Technology.
6-8 Physical and Chemical Properties of Sediment Samples 6-25
Collected from a Waste Lagoon.
6-9 Characteristics and Components of the Wastewater 6-26
that are Potentially Aggressive to FMLs.
6-10 FML Samples Collected from the 100-Mil HOPE Liner 6-27
For a Lagoon Located in the Northeast
6-11 Properties of HOPE Lagoon Liner After Approximately 6-30
4.75 Years in Service.
6-12 Volatiles Content of Specimens of the HOPE FML taken at 6-31
Increasing Depths in the Waste Lagoon.
6-13 Comparisons of the TGA, DSC, and Specific Gravity of 6-31
Three HOPE FMLs.
6-14 General Analysis of Sludge Liquid. 6-33
6-15 Field Observations of FML Samples from an Industrial 6-36
Sludge Lagoon.
6-16 Physical and Analytical Properties of Weathered Samples 6-38
of PVC FML Exposed in a Calcium Sulfate Sludge Lagoon.
liv
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6-17 Physical and Analytical Properties of Samples from a 6-39
Vertical Cross Section of PVC FML Exposed in Calcium
Sulfate Sludge Lagoon.
6-18 Seam Strength of PVC FML Exposed in Calcium Sulfate 6-40
Sludge Lagoon.
6-19 Properties of 20-Mil PVC FML Exposed as MSW Landfill 6-43
Liner Compared with an Unexposed 20-Mil PVC FML.
6-20 Composition of Surface Water Sample. 6-45
6-21 Properties of 60-Mil EPDM FML Samples Collected from 6-48
the Emergency "Red-Water" Basin.
6-22 Seam Strength in Shear and Peel Modes of 60-Mil EPDM 6-50
Seam Samples Collected from the Emergency "Red-Water"
Basin.
6-23 Comparison of Analytical Properties of Exposed Sample 6-51
and Baseline Reference.
6-24 Summary of Case Studies by Giroud. 6-56
6-25 Summary of Case Studies of FMLs by Ghassemi. 6-68
6-26 Summary Description of "Failures" at Case Study Sites. 6-73
6-27 Grab Strength of a Monofilament Woven Polypropylene 7-79
Geotextile that had been in service for 10 years.
6-28 Properties of a Monofilament Woven Polypropylene 6-80
Geotextile that had Been in Service for 10 Years.
6-29 Experience with Leachate Collection and Removal Systems. 6-83
7-1 Site-Specific Factors to be Considered in Designing 7-7
a Waste Containment Unit.
7-2 Summary of Hydraulic Conductivity Measurements at 7-54
site in Central Texas.
7-3 Granular Media that Might be USED in Leachate 7-70
Collection and Removal Systems.
9-1 Compaction Equipment and Methods. 9-8
9-2 Equipment and Materials for Installing FMLs. 9-28
9-3 Nondestructive Tests Used to Evaluate Seam Continuity. 9-46
Iv
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10-1 Sample Recommendations for Construction Documentation 10-11
of Clay-Lined Landfills.
10-2 Specifications and the Number of Specimens Tested Per 10-17
Sample of a CPE FML Used in Construction of fit. Elbert
Forebay Reservoir.
11-1 Potential Problems with Final Cover Systems. 11-24
12-1 Potential Cost Elements of a Waste Containment Unit. 12-3
12-2 Installed 1987 Costs for Flexible Membrane Liners. 12-6
12-3 Geotextile Costs. 12-7
12-4 Costs of Geocomposite Drainage Mats. 12-8
12-5 Range of Costs for Sand and Gravel. 12-9
12-6 Costs for Pipe of Different Types. 12-10
12-7 Unit Costs for Major Embankment Components. 12-11
12-8 Specifications for Unit Used to Estimate Cost 12-13
of Leachate Collection and Removal Systems.
12-9 Cost Comparison Between Granular and Synthetic 12-14
Drainage Systems.
12-10 Construction Costs for a Surface Impoundment 12-15
Designed to Contain Five Feet of Liquid.
12-11 Cost Estimates for Soil Cement, Asphalt Concrete, 12-16
and Asphalt Membrane Liners.
12-12 Comparison of Cumulative Costs Over 20 Years of 12-18
Four Alternative Technologies.
12-13 Cost of Quality Assurance. 12-20
12-14 Cost of Third Party Quality Assurance for Double- 12-20
Lined 500,000 ft2 Waste Landfill Unit.
A-l Composition and Analysis of an Average Municipal Refuse A-3
From Studies by Purdue University.
A-2 Parameters for Characterizing MSW Leachate. A-4
A-3 Composition of Three MSW Landfill Leachates. A-5
Ivi
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A-4 Characteristics of MSW Leachates. A-6
A-5 Representative Hazardous Substances Within Industrial A-8
"Wastes Streams.
A-6 Typical Electroplating Solutions. A-ll
A-7 Characterization of Waste Stream from Electroplating A-13
Industry.
A-8 Hazardous Wastes Destined for Land Disposal from the A-14
Electroplating and Metals Finishing Industry.
A-9 Potentially Hazardous Waste Streams Generated by the A-15
Metal Swelling and Refining Industry.
A-10 Ranges of Concentrations and Total Quantities for A-19
Refinery Solid Waste Sources.
A-ll Raw Waste Constituents from the Pharamaceutical A-21
Industry.
A-12 Chemical Analysis of Primary and Secondary Treatment A-22
Sludges from the Pulp and Paper Industry.
A-13 Uranium Mill Leachate Compositions. A-25
A-14 Elemental Maximum Concentrations and Other Parameters A-27
in Various Waste Streams from Coal Combustion.
A-15 Range of Concentrations of Chemical Constituents in A-28
FGD Sludges from Lime, Limestone, and Double-Alkali
Systems.
A-16 Composition of Boiler Blowdown. A-30
A-17 Fireside Wastewater Characteristics A-30
A-18 Ion-Exchange Regeneration Wastes. A-31
A-19 Annual Solid Waste Production Statistics at Surface A-32
and Underground Mines - Metals.
A-20 Annual Solid Waste Production Statistics at Surface A-33
and Underground Mines - Nonmetals.
A-21 Common Flotation Reagents Used in the Recovery of Minerals A-34
from Ores.
Ivii
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D-l Recommendations for Tensile and Tear Testing for Pouch D-5
Test.
E-l Suggested Solvents for Extraction of Polymeric FMLs. E-3
F-l Test Methods Used to Determine Properties of Polymeric F-2
FMLs.
F-2 Properties of Unexposed Polymeric FMLs. F-4
F-3 Physical Properties of Unexposed Semicrystalline Polymeric F-9
FMLs and Commerical Sheetings Tested at Two Inches Per
Minute.
F-4 Test Methods Used to Determine Physical and Analytical F-ll
Properties of Polymeric FMLs.
F-5 Solvents Used for Extraction of Polymeric FMLs. F-12
F-6 Details of Tesnile and Tear Resistance Test Methods Used F-13
in Testing.
F-7 Analytical and Physical Properties of Chlorinated F-14
Polyethylene, Chlorosulfonated Polyethylene, and
Epichlorohydrin Rubber FMLs.
F-8 Analytical and Physical Properties of Ethylene Propylene F-15
Rubber, Ethylene Vinyl Acetate, Neoprene, Polybutylene,
and Polyester Elastomers FMLs.
F-9 Analytical and Physical Properties of Low-Density F-16
Polyethylene, Linear Low-Density Polyethylene, High-
Density Polyethylene Alloy FMLs.
F-10 Analytical and Physical Properties Polyurethane, F-17
Polyvinyl Chloride, Elasticized Polyvinyl Chloride,
and Oil-Resistant Polyvinyl Chloride FMLs.
F-ll Composition of Laboratory-Prepared Compounds of F-19
CSPE, Nitrile Rubber, and Polyvinyl Chloride.
F-12 Molding Conditions and Extractables of the F-20
Laboratory-Prepared Compounds.
H-l Recommendations for Tensile and Tear Testing for Tub Test. H-6
J-l Analyses of Hazardous Wastes Used in Exposures Reported J-2
by Haxo.
Iviii
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K-l Suggested Properties and Methods for Testing FMLs for K-3
Standards and Specifications.
K-2 Titles of ASTM Test Methods and Specifications Used K-4
with FMLs.
K-3 Suggested Standards for Unreinforced FMLs - Thermoplastic K-6
FMLs of Chlorinated Polyethylene, Polyvinyul Chloride, and
Polyvinyl Chloride, Oil-Resistant.
K-4 Suggested Standards for Unreinforced FMLs - Polyethylene K-7
FMLs.
K-5 Suggested Standards for Fabric-Reinforced FMLs - FMLs K-8
with Thermoplastic Coatings of Chlorinated Polyethylene
(CPE), Chlorinated Polyethylene-Alloy, (CPE-A), and
Ethylene Interpolymer Alloy (EIA).
K-6 Suggested Standards for Fabric-Reinforced FMLs, Thermo- K-9
plastic Chlorosulfonated Polyethylene (CSPE).
L-l Physical Testing of Exposed Membranes in Liner-Waste L-5
Liquid Compatibility Test.
M-l Observations and Tests for the Construction Quality M-5
Assurance and Quality Control of Hazardous Waste
Disposal Facilities.
lix
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ABBREVIATIONS AND SYMBOLS
A
A
AA
ABS
AEM
AET
Ag
Al
ALR
AM
API
As
ASAE
ASTM
atm
3
b
B
Ba
Be
Bi
Bit
BOD
BODs
BTU/lb
c
C
Ca
ca
Ca
CaCl2
CaCOs
CaF2
cal
cal/g
CC14
Cd
CED
CERCLA
Angstrom
Available; Area of flow; Inside cross-sectional
area of a sample container; Acetone
Atomic absorption
Acrylonitrile-butadiene-styrene
Acoustical emission monitoring
Actual evapotranspi ration
Silver
Aluminum
Action leakage rate
Amorphous
American Petroleum Institute
Arsenic
American Society of Agricultural Engineers
American Society for Testing and Materials
Atmosphere, unit of pressure
Slope angle
Experimentally obtained constant
Boron
Barium
Beryllium
Bismuth
Bitumin
Biochemical oxygen demand
Biochemical oxygen demand (5 days)
British Thermal Units per pound
Soil cohesion
Celsius
Adhesion
Approximately
Calcium; shear strength parameters of adhesion
Calcium chloride
Calcium carbonate
Calcium fluoride
Calorie
Calories per gram
Carbon tetrachloride
Cadmium
Cohesive energy density
Comprehensive Environmental Response, Compensation
and Liability Act (Superfund)
Ix
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CFR Code of Federal Regulations
CH3OH Methyl alcohol
CH4 Methane
CHRONS Carbon, hydrogen, oxygen, nitrogen, sulfur
Cl Chloride
cm Centimeter
cm s~l Centimeters per second
CO Epichlorohydrin polymer
C02 Carbon dioxide
Co Cobalt
COD Chemical oxygen demand
cP Centipoise
CPE Chlorinated polyethylene
CQA Construction quality assurance
CQC Construction quality control
CR Chloroprene rubber - neoprene
Cr Chromium
CSPE Chlorosulfonated polyethylene
CSPE-LW Chlorosulfonated polyethylene - low water absorption,
i.e. industrial grade
Cu Copper
cu Cubic
cu yd Cubic yard
CX Crystalline or semi crystalline thermoplastic
D Dissolved or disintegrated; Diffusion coefficient
d Day, denier
dsoil Some particle size of the soil (often dss)
Particle size, at which 85% of the soil is finer
Friction angle, potential energy of organics
6d Dispersive parameter
<5n Hydrogen bonding parameter
60 Hildebrand solubility parameter
6p Polarity parameter
6t Total Hansen solubility parameter
AE Energy required to vaporize one mole of material
AHf Heat of fusion
Ah Hydraulic head difference
Ap Vapor pressure difference
db Dry basis
ODD Di chlorodiphenyldi chloroethane
DDT Di chlorodi phenylt ri chloroethane
DEHP di(ethyl-hexyl) phthalate
DI Deionized
DMK Dimethylketone
OOP Dioctyl phthalate
ORE Destruction and removal efficiency
DSC Differential scanning calorimetry
e Deformation
ea Each
EC Electrical conductivity
Ec Cohesion efficiency
Ixi
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ECB Ethylene copolymer with bitumen
ECO Epichlorohydrin rubber (copolymer of ethylene
oxide and chloromethyl oxirane)
e.g. For example
Eh Redox potential
EIA Ethylene interpolymer alloy
ELPO Elasticized polyolefin
EMMAQUA Equatorial Mount with Mirrors for Acceleration Plus
Water Spray (Accelerated outdoor weathering using
concentrated natural sunlight)
E<|> Friction angle efficiency
EP Expanded polystyrene, extraction procedure
EPA Environmental Protection Agency
epi Ends per inch
EPDM Ethylene propylene rubber
EPRI Electric Power Research Institute
EPTC Extraction Procedure for Toxic Characteristic
ER Electrical resistivity
ESC Environmental stress cracking
et al And others
etc And the like
EVA Ethylene vinyl acetate
F Fluorine; Fahrenheit
FDC First derivative computer
Fe Iron
FGD Flue gas desulfurization
FLEX Flexible liner evaluation expert
FML Flexible membrane liner
FR Fabric-reinforced
FS Flow rate factor of safety; factor of safety
ft Foot
FTB Film tear bond
FTMS Federal Test Method Standard
Yd Dry density
Ydmax Maximum dry density
Ydtar Target density
Yt Total (or wet) density
GC Gas chromatography
GC/MS Gas chromatography/mass spectroscopy
g Gram
g/cm Grams per centimeter
g/kg Grams per kilogram
g/L Grams per liter
g/mL Grams per milliliter
gal Gallon
gal/sq yd Gallons per square yard
Ge Germanium
gpad gallons per acre per day
gpm Gallons per minute
GTR Gas transmission rate
h Hour; Height
Ixii
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H
H20
H2S
HAC
HC1
HOPE
HDPE-A
HELP
HFL
Hg
HIPS
HN03-HF-HOAc
HSGC
HSWA
i
i.e.
IIR
in.
ipm
IR
k
K
kg
kN
kn
KOH
kPa
kn
L
Ib
Ibf
Ib/ft
LCRS
LDCRS
LDPE
LF
LLDPE
Li
LiCl
LPG
LVT
m
yg
yg/kg
yg/L
yL
ym
ymho
ymho/cm
Height
Water
Hydrogen sulfide
Hydraulic asphalt concrete
Hydrochloric acid
High-density polyethylene
High-density polyethylene - alloy
Hydrologic Evaluation of LaYidfill Performance
Hydrofluoric acid waste
Mercury
High impact polystyrene
Nitric acid-hydrofluoric acid-acetic acid waste
Headspace gas chromotography
Hazardous and Solid Waste Amendment of 1984
Hydraulic gradient
That is
Isobutylene-isoprene rubber (butyl rubber)
Inch
Inches per minute
Infrared
Darcy's coefficient of permeability
Potassium; permeability
Kilogram
Kilonewton
Permeability normal to the plane of the fabric
Potash
Kilopascal
Planar coefficient of permeability
A value depending on soil density, gradation,
fabric-type, etc.
Liter, length
Pound
Pounds (force)
Pounds per foot
Leachate collection and removal system
Leak detection, collection and removal system
Low-density polyethylene
Lineal foot
Linear low-density polyethylene
Lithium
Lithium chloride
Low-pressure gas
Low temperature curing cement
Meter
Micrograms
Micrograms
Micrograms
Microliter
Micrometer
Micromho
Micromhos per centimeter
per kilogram
per liter
Ixiii
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MBAS Methylene blue active substances
meal Millicalorie
meal/sec Millicalories per second
MDPE Medium density polyethylene
MEK Methyl ethyl ketone
Mg Magnesium
mg Milligram
mg Cl/L Milligrams of chloride per liter
mg/kg Milligram per kilogram
mg/L Milligram per liter
MIBC Methyl isobutyl carbinol
mil Inch x 0.001
min. minute
MJ Millijoule
mL Mi Hi liter
mL/L Milliliters per liter
mL/min. Milliliters per minute
mm Millimeter
Mn Manganese
Mo Molybdenum
mo Month
MP Melting point; Mega poise
MPa Mega pascals
MSW Municipal solid waste
MT6 Minimum Technology Guidance
MTM Matrecon Test Method
MW Molecular weight
n Number of reinforcement layers
N Nitrogen; Newton
N£ Nitrogen
Na Sodium
NA Not available
na Not applicable
NaCl Sodium chloride
NaOH Sodium hydroxide
NBR Nitrile rubber
NBS National Bureau of Standards
n.d. No date
ND None detected
ng Nanogram
ng/L Nanograms per liter
NH3 Ammonia
NH4 Ammonia salts
Ni Nickel
N/m Newtons per meter
N02 Nitrite
N03-N Nitrate nitrogen
NSF National Sanitation Foundation
03 Oxygen
Ofabric some opening size of the fabric
095 95% opening size of the fabric
OIT Oxidative induction time
Ixiv
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oz Ounce
<|> Soil friction angle
i|> Permittivity
i|*act Actual, or test, value
ijjreq'd Required, or design, value
£ Phosphate; Primary function; Precipitation
P Permeability coefficient, gas
PA Polyamide-nylon
PB Polybutylene
Pb Lead
PCA Portland Cement Association
PCB Polychlorinated biphenyls
pCi/L Pico curie per liter
PCCP Post-closure care period
PE Polyethylene
PEL Polyester elastomer
PERC Percolation
perm Permeance
PET Polyester terphthalate
PIB Polyisobutylene
Po Polonium
POA Percent open area
PP Polypropylene
ppi Pounds per inch
ppm Parts per million
psf Pounds per square foot
psi Pounds per square inch
PU Polyurethane
PVC Polyvinyl chloride
PVC-E Polyvinyl chloride, elasticized
PVC-OR Polyvinyl chloride, oil-resistant
Q,q Rate of flow
QA/QC Quality assurance/quality control
qt Quart
p soil bulk density
R Fabric-reinforced; radius of failure arc
Ra Radium
RAP Response Action Plan
RCRA The Resource Conservation and Recovery Act
RH Relative humidity
RLL Rapid and extremely large leakage
RO Surface run off
RQD Rock quality designation
on Normal stress
av Vertical stress
S Secondary function; Solubility coefficent
S/S Solidification/stabilization
s Second
S-100 Stress at 100% elongation
S-200 Stress at 200% elongation
SAE Society of Automotive Engineers
Ixv
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Sb Antimony
SBR Styrene-butadiene rubber
SDRI Sealed double-ring infiltrometer
Se Selenium
sec Second
Si Silicon
S02 Sulfite
S04 Sulfate
SP The SP grade of coarse sand under USCS
sq Square
sq ft Square foot
sq yd Square yard
Sr Strontium
ST Soil moisture storage
STP Standard temperature and pressure
SVT Solvent vapor transmission
T Shear stress of the soil; Shear strength of the soil
e Transmissivity
T-j Allowable strength of geogrids
t Thickness of the fabric; Time
Ta Tantalum
TBP Tributyl phosphate
TCA 1,1, 1-trichloroethane
TCLP Toxicity Characteristic Leaching Procedure
TCE Trichloroethylene
TDR Time-domain reflectometry
TDS Total dissolved solids
TGA Thermogravimetric analysis
Th Thorium
THF Tetrahydrofuran
Ti Titanium
T-j Allowable strength of geogrid or geotextile
Tm Melting temperature of crystaline phase
TMTDS Tetramethyl thiuram disulfide
TN-PVC Thermoplastic nitrile
TOC Total organic carbon
TOX Total organic halides
TP Thermoplastic
TRD Technical Resource Document
TS Total solids
TSDF Treatment, storage, and disposal facility
TSS Total suspended solids
TVA Total volatile acids
TVS Total volatile solids
U Uranium; unreinforced
USCS Unified Soil Classification System
USLE Universal Soil Loss Equation
UV Ultraviolet
V Vanadium
VE Percent volatiles of a sample after exposure
Vm Molar volume
Ixvi
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vs versus
wopt Optimum water content
W Width; waste; moisture (or water) content;
Weight of failure zone
wt Weight
WVT Water Vapor Transmission
x Xylene
X Moment arm to centroid of failure zone
XL Crosslinked
yd Yard
Y-j Moment arms to each level of geogrid
Yr Year
Zn Zinc
Zr Zirconium
Ixvii
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ACKNOWLEDGMENTS
This document was prepared by Matrecon, Inc., Alameda, California,
under a contract with the Risk Reduction Engineering Laboratory, U.S. Envir-
onmental Protection Agency, Cincinnati, Ohio. Henry E. Haxo, Jr., was
Principal Investigator on this project.
The following personnel participated in writing the new text of this
document:
Matrecon, Inc.:
Henry E. Haxo, Jr.
Paul D. Haxo
Lawrence C. Kamp
Drexel University, Philadelphia, PA:
Robert M. Koerner
We gratefully acknowlege the contributions of the following who partici-
pated in the preparation of the previous edition of this Technical Resource
Document, dated March 1983, portions of which have been retained:
- K. W. Brown, Texas A & M University, College Station, TX.
- Michael P. Miklas, Southwest Research Institute, San Antonio, TX.
- John G. Pacey, Emcon Associates, San Jose, CA.
- David W. Shultz, formerly of Southwest Research Institute, San
Antonio, TX.
We also gratefully acknowledge the peer review personnel who reviewed
the draft of this report:
- Hans August, Bundesanstalt fur Materialprufung, Berlin.
- Mark Cadwallader, Gundle Lining Systems, Inc.
- Judy Dean, Industrial Fabrics Association International.
- Gerald Fisher, Emcon Associates/Poly-America.
Ixviii
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Ronald Frobel, Geosynthetics Engineering Consulting Services.
Detlef Grimski, Umweltbundesamt, Berlin.
R. Koch, Hoechst AG, Frankfurt.
Robert M. Koerner, Drexel University.
Robert LaBoube, Chemical Waste Management, Inc.
Clarke Lundell, Waste Management, Inc.
Francis G. McLean, U.S. Department of the Interior.
D. H. Mitchell, Battelle.
William C. Neal, Poly-America, Inc.
Anthony 0. Ojeshina, Schlegel Lining Technology, Inc.
Zia Qureshi, Western Waste Industries.
Gregory N. Richardson, S&ME.
M. A. Schoenbeck, E.I. du Pont de Nemours & Co., Inc.
Patrick Snell, Allied Signal.
Klaus Stief, Unweltbundesamt, Berlin.
Felon R. Wilson, Seaman Corporation.
John P. Workman, Browning-Ferris Industries.
Ixix
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-------
CHAPTER 1
INTRODUCTION
1.1 BACKGROUND
In 1965 Congress passed the Solid Waste Disposal Act, the first federal
statute to require safeguards and encourage environmentally sound methods for
disposing of wastes. Congress amended this law in 1970 and again in 1976
by passing the Resource Conservation and Recovery Act (RCRA), PL-94-580.
Subtitle C of this act required the U.S. Environmental Protection Agency
(EPA) to establish a Federal hazardous waste management program and mandated
that the EPA promulgate regulations establishing performance standards and
requirements for the location, design, and construction of hazardous waste
treatment, storage, and disposal facilities (TSDFs). Subtitle D established
a cooperative framework for Federal, State, and local governments to control
the management of solid wastes not covered by Subtitle C. The goal of RCRA
is to ensure that waste TSDFs are designed, constructed, and operated in a
manner that protects human health and the environment.
The EPA has issued a series of waste regulations under Subtitles C and
D of RCRA in the Code of Federal Regulations (CFR). On September 13, 1979,
the EPA first promulgated criteria for classification of solid waste disposal
facilities and practices (40 CFR 257). These criteria established minimum
performance standards for all solid waste storage and disposal facilities.
On May 19, 1980, EPA issued general standards that identified which wastes
were hazardous and created a system for the management of hazardous wastes
which included a tracking system to monitor the movement of hazardous wastes
from the point of generation to final disposal (40 CFR 260-65). These
general standards also delineated basic performance objectives necessary
for safe handling and control of hazardous wastes during generation, trans-
port, treatment, storage, and disposal.
As knowledge about the environmental impacts of waste disposal increased
and technology for the handling of hazardous wastes developed, Congress revised
RCRA again in 1984. These amendments are also known as the Hazardous and
Solid Waste Amendments of 1984 (HSWA), PL-98-616. HSWA established minimum
technological requirements for new hazardous waste landfills and surface
impoundments and required the EPA to promulgate regulations or issue guidance
documents regarding the implementation of these requirements. Since then,
the EPA has promulgated regulations detailing operation and design requirements
for hazardous waste TSDFs. These regulations have been incorporated in 40
CFR 264. The EPA has also issued for comment and use draft minimum technology
1-1
-------
guidance (MTG) documents on double liner systems for hazardous waste landfills
and surface impoundments (EPA, 1985) and on final cover systems for hazardous
waste landfills and surface impoundments (EPA, 1987a). Both the minimum
technology requirement regulations and the MTG documents are presently under
review. EPA eventually will formalize additional technology guidelines by
incorporating them into the Agency's regulations. HSWA also mandated continued
review of the performance standards for Subtitle D (nonhazardous) solid waste
TSDFs to determine whether the current criteria are adequate for protecting
human health and the environment.
One method of protecting the environment and human health is to prevent
hazardous and toxic waste constituents from migrating out of a waste TSDF
unit into other areas, particularly the groundwater. To a great extent, this
can be accomplished by controlling the liquid components of the impounded
waste. Two strategies are being used to control liquids: one is to prevent
any liquids present in the unit from escaping into the surrounding environ-
ment; and the other, in the case of landfills, is to minimize leachate
generation by keeping liquids out of the unit. Methods of keeping liquids
out include building a cover on top of the landfill at the end of its active
life, banning the disposal of liquids, preventing surface run-off from
entering the unit, etc.
Placing hazardous wastes in lined TSDF units is a key element in the
Federal waste management program. Except in cases where the conditions for
statutory variance are met, HSWA required new hazardous waste landfills and
surface impoundments to have two or more liners, a leachate collection and
removal system (LCRS) between these liners, and (in the case of a landfill)
an LCRS above these liners. The different components of the lining system
include flexible membrane liners (FMLs), soil liners, and the components of
the LCRSs. Present EPA guidance requires the bottom liner to be a composite
liner consisting of both an FML and a soil liner, and the top liner to be, at
a minimum, an FML. A liner is a barrier that greatly restricts the migration
of liquids. No single liner, however, can prevent the migration of some
liquids due to vapor transmission or leakage caused by either imperfect
installation or breaches that develop during service. In addition, a liner
does not have structural strength. Only as a component of an engineered
system with a rigorous operational program can a liner minimize the migration
into the environment of hazardous constituents placed in land storage or
disposal units. FMLs are also used as barriers in final covers for landfills
to control the infiltration of water (e.g. from rain, surface run-off, etc.)
into the closed unit.
Other important components of a lining system include the LCRSs. These
systems can be comprised of both synthetic and granular materials. In a
landfill, the purpose of the LCRS above the top liner is to minimize the head
of leachate on the top liner during the active life of the landfill and to
remove liquids during the post-closure care period. The purpose of the LCRS
between the two liners is to rapidly detect, collect, and remove all liquids
that enter the LCRS throughout the active life and post-closure care period
of the unit.
1-2
-------
As a whole, the liquids management system attempts to:
- Minimize leachate generation in a landfill or a waste pile unit during
its active life.
- Collect and remove all pumpable quantities of leachate generated in a
unit (in the case of landfills and waste piles).
- Collect and remove all pumpable quantities of liquids that pass
through the top liner of a double liner system.
- Operate the unit up through closure without the escape of liquids (in
the case of waste piles and surface impoundments) or leachate (in the
case of landfills).
- Control the generation of leachate within a closed landfill unit.
At present, except in cases that meet criteria for statutory variance,
EPA regulations require two types of hazardous waste TSDF units to meet the
double liner requirement:
- Surface impoundments.
- Landfills.
Proposed rules extending the double liner requirement to waste piles have
been published in the Federal Register (EPA, 1987b). Waste piles are non-
containerized accumulations of solid waste. They can be used for treatment
as well as storage of dry materials and are temporary in nature. Surface
impoundments are for the temporary storage and treatment of liquids. Land-
fills are for the permanent disposal of solid wastes on land.
At present, there are no technological design requirements for units
for containing Subtitle D (nonhazardous) wastes, though proposed regulations
are due to be published in the near future. Nevertheless, lining Subtitle D
waste containment units may be desirable or necessary given particular site
conditions or the specific waste stream in order to meet the performance
standard criteria stated in 40 CFR Part 257. Subtitle D wastes include
municipal solid waste (MSW), nonhazardous industrial waste, municipal sludge,
municipal waste combustion ash, construction and demolition waste, agri-
cultural waste, oil and gas waste, and mining waste.
Depending on the type of service required, waste containment units may
need to function from a relatively few years, as in the case of some storage
facilities, up to 100 years or more, as in the case of some landfills, and to
function in such a manner that hazardous or toxic materials are under control
and do not migrate from the unit in an uncontrolled manner.
1.2 PURPOSE OF THIS TECHNICAL RESOURCE DOCUMENT
Lining a containment unit is a feasible means of protecting the ground-
water from hazardous or toxic waste constituents. This Technical Resource
1-3
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Document (TRD) provides information on the selection, design, construction,
and performance of various lining and cover systems based on current tech-
nology, with particular emphasis on FMLs and the containment of hazardous
wastes. However, information appropriate to the containment of nonhazardous
wastes and the use of lining materials in mining applications is also pre-
sented. The discussion of soil liners is limited to their use in composite
liners in double-liner systems; for further information the reader is di-
rected to a companion TRD (Goldman et al, 1985). The information presented
in this document is intended to assist the user in determining what FMLs
would be effective in containing specific wastes or waste leachates.
Effective control for containment units means minimizing the migration of
hazardous or toxic waste constituents into and through the lining system.
1.3 SCOPE
Chapter 2 discusses the types of waste liquids and leachates that may
contact a lining system. The discussion of leachates includes the liquids
that may constitute the leachates and the dissolved constituents that are
carried by these liquids. This chapter describes the basic types of waste
liquids and hazardous substances that may require secondary containment.
Trends in the types of wastes and substances that are being contained in
land-based storage and disposal units are also discussed.
Basic concepts and factors in the transport of mobile constituents
of a solid or liquid waste placed in a containment unit and the escape of
these constitutents into the environment are discussed in Chapter 3. The
paths and mechanisms by which these constituents are transported within a
unit are discussed with particular emphasis on transport within a multi-
layered liner system, including the FML and soil liners and the leachate
collection and removal systems because the migration and partitioning of
mobile constituents to specific subcomponents of a lining or cover system may
adversely affect the performance of the system. This chapter concentrates on
closed FML-lined landfills and FML-lined surface impoundments that meet the
requirements of RCRA and its amendments.
Chapter 4 describes various types of materials and products that are
used in the design and construction of lined waste containment units and
presents data concerning their properties. These materials, which are needed
to fulfill a variety of functions in the structure of these containment units
include FMLs, geotextiles, geogrids, geonets, geocomposites, sand and gravel,
concrete, pipe, and soil, which are used for preventing migration, separa-
tion, support, soil reinforcement, filtration, and drainage.
The long-term effects of waste liquids and environmental stresses on
FMLs and ancillary construction materials, as demonstrated in laboratory and
pilot-scale field studies, are discussed in Chapter 5. As background to
this discussion, the environments that FMLs and other materials may encounter
in various types of actual waste containment units are described. These
environmental conditions either have been observed or are considered highly
probable. The types of units discussed include MSW landfills, surface
impoundments, hazardous waste landfills, waste piles, leach pads, secondary
containment facilities, and tailings ponds.
1-4
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Chapter 6 reviews selected field studies on FMLs and other related
materials of construction in service environments with particular emphasis on
the durability of these materials. Various factors that could contribute to
the failure of an FML-lined unit are described. The properties of the
studied materials are described to provide a basis for correlating field
performance with the results of laboratory and pilot-scale tests in order
to develop performance-related tests and to establish performance criteria
for the use of FMLs in service environments.
Chapter 7 discusses the minimum performance and technological re-
quirements for the design of lined waste containment units and reviews
engineering options available to the designer, with particular emphasis on
designing a double-lined containment unit for the disposal or storage of
hazardous wastes. The same design principles would readily be adopted for
single-lined units for the containment of nonhazardous wastes or materials.
Chapter 8 discusses specification documents for the construction of
waste containment units with particular emphasis on the technical specifica-
tions which include the plans, specifications, and drawings that are neces-
sary for bid packages and which are necessary to communicate to construction
and installation contractors the quality of the materials of construction
required by the design and the quality of work to be performed during con-
struction.
Chapter 9 discusses various steps in constructing and installing the
major components of double-lined waste containment units including:
- Earthworks, including the soil component of a composite liner.
- FMLs.
- Leachate collection and recovery systems.
- Final cover systems.
Chapter 9 also discusses special considerations in FML installation, such as
installation around appurtenances, and the construction of admixed liners.
Chapter 10 reviews EPA guidelines for construction quality assurance
(CQA) plans pertaining to the construction of hazardous waste containment
units with particular emphasis on the tests and types of observations in-
volved in CQA during construction of a containment unit.
The measures that must be taken in managing a waste containment unit
from the time of commencement of operations through the operational and
post-closure care periods are described in Chapter 11. These measures
include the standard operating procedures that must be developed at the time
the permit application is prepared. The need for controlling the incoming
waste, and methods of monitoring the performance of the in-service lining
systems, the earthworks, and final cover systems are described.
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Chapter 12 discusses factors influencing the cost of constructing a
waste containment unit and discusses the cost of various liner materials as
well as other construction materials such as pipes, geogrids, geonets,
drainage materials, etc. Some costs for earthworks construction and factors
that can affect liner installation costs are presented. The cost of dif-
ferent storage or disposal alternatives are compared, and lastly, costs for
quality assurance inspection of the materials and the construction are
discussed.
More detailed information on subjects discussed in the main body of the
document is presented in the appendixes. Appendix A presents examples of
significant waste sources and the types of wastes generated by these sources.
Appendix B lists companies that provide liner materials and services.
Polymers which were formerly used in the manufacture of FMLs are described in
Appendix C. Appendix D describes the pouch test for permeability of poly-
meric FMLs. A procedure for determining the extractables contents of exposed
and unexposed FMLs is presented in Appendix E. The results of testing a wide
range of unexposed polymeric FMLs and other commercial sheetings for physical
and analytical properties are presented in Appendix F. A procedure for
determining the volatiles contents of exposed and unexposed FMLs is presented
in Appendix G. Appendix H describes the tub test of polymeric FMLs. Special
considerations in designing a leachate collection system network are de-
scribed in Appendix I. Appendix J summarizes the results of analyzing
hazardous and toxic wastes used in the exposure tests which are discussed in
Chapter 5. Appendix K presents, suggested property standards for selected
FMLs. Appendix L reprints the EPA Method 9090 compatibility test for wastes
and FMLs (EPA, 1986). Appendix M lists observations that should be made and
tests that should be performed for the CQA and construction quality control
(CQC) of hazardous waste containment units. Appendix N presents locus-of-
break codes that can be used in reporting the results of testing FML seams.
This document attempts to bring together current knowledge and tech-
nology related to lining and cover systems; the information presented is
selected for use by site owners and operators, permit writers, and those
responsible for preparing permit applications to aid them in gaining a
comprehensive understanding of the numerous elements involved in the design
and construction of waste containment units. This document can also be used
by researchers, materials and component suppliers, and the general public as
a source of information on the design of hazardous waste as well as other
types of storage and disposal units.
This document refers to, but does not discuss, the following subjects:
- Site selection.
- Detailed discussion of methods of analysis of wastes, except for
information on waste components that are aggressive to linings of
all types.
- Monitoring of groundwater.
1-6
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- Attenuation of pollutants in the native soil below the lining system
(subsurface).
- Soil characteristics and behavior in waste containment applications.
- Legal aspects, except insofar as they affect the design or operation
of a containment unit.
1.4 REFERENCES
EPA. 1985. Minimum Technology Guidance on Double Liner Systems for Land-
fills and Surface Impoundments. EPA 530-SW-85-014, May 24, 1985.
U.S. Environmental Protection Agency. Washington, D.C.
EPA. 1986. Method 9090. Compatibility Test for Wastes and Membrane
Liners. In: Test Methods for Evaluating Solid Waste. Vol. 1: Labora-
tory Manual , Physical/Chemical Methods. 3rd 'ed. SW-846. U.S. Environ-
mental Protection Agency, Washington, D.C. September 30, 1986.
EPA. 1987a. Minimum Technology Guidance on Final Covers for Landfills and
Surface Impoundments. Draft. EPA Contract No. 68-03-3243, Work Assign-
ment No. 2-14. U.S. Environmental Protection Agency, Washington, D.C.
31 pp.
EPA. 1987b. Liners and Leak Detection for Hazardous Waste Land Disposal
Units; Notice of Proposed Rulemaking. Federal Register 52(103):20218-
20311.
Goldman, L. J., A. S. Damle, G. L. Kingsbury, C. M. Northeim, and R. S.
Truesdale. 1985. Design, Construction, and Evaluation of Clay Liners
for Hazardous Waste Facilities. EPA 530/ SW-86-007F. U.S. Environmental
Protection Agency, Washington, D.C. 575 pp.
1-7
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CHAPTER 2
CHARACTERISTICS OF WASTE LIQUIDS AND LEACHATES
2.1 INTRODUCTION
In waste management, groundwater protection, and pollution control, the
liquid components of wastes contained in treatment, storage, and disposal
facilities (TSDFs) are of primary concern. Even though placing bulk or
noncontainerized liquid hazardous wastes or hazardous wastes containing
free liquids in landfills was prohibited as of May 8, 1985 (40 CFR 264.314),
the disposal of solid wastes can result in leachates generated by the per-
colation of liquids (e.g. rainwater) through the waste. Without adequate
control, waste liquids and leachates can migrate out of a containment unit
carrying constituents that may pollute the groundwater. By lining a waste
containment unit with an engineered lining system which includes a low-
permeability liner, e.g. a flexible membrane liner (FML), the migration
of liquids out of the unit can be controlled. At the same time, liquids or
constituents dissolved in the liquids present in a lined containment unit may
interact with components of the lining system. Thus, knowledge of the
composition of the liquid to be contained, including that of the dissolved
constituents,, is important in selecting the specific materials to be used in
constructing the lining system for a given containment unit. Because such
specific information is generally not available, the EPA has developed Method
9090 to determine the compatibility of FMLs proposed for use in constructing
a liner system with the waste liquid or leachate to be contained (EPA,
1986a).
Even though inorganic constituents of a given waste liquid or leachate
may affect organic solubility, the organic constituents are of principal
importance in determining the compatibility of the polymeric components of a
lining system and a given waste liquid since they can potentially be absorbed
by polymeric compounds or extract components of a compound resulting in
changes in mechanical properties. In the case of FMLs, absorption of an
organic species can also result in permeation of that species. An organic
waste or sludge with an organic liquid phase will most probably expose the
liner to the organic species contained in the waste. The examples presented
in this chapter and in Appendix A show that the wastes disposed of in in-
dustrial waste containment units cover the spectrum of chemical species.
It should be noted that organics are subject to regulatory control. The
effects of organics on polymeric materials is discussed in Chapter 5.
2-1
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Two conditions that can be encountered, particularly in surface im-
poundments, by an in-service FML in contact with waste liquids containing
organics are presented schematically in Figure 2-1. In the first condition,
the waste liquid that contacts the FML consists of water with dissolved
organics and probably some inorganics. In the second condition, the FML is
in direct contact with a mixture of organic liquids. This condition has been
encountered in the field when the organics, having a higher specific gravity
than the aqueous waste liquid, exceed their solubility in water and pool
above the FML. The concentration of organics in the waste directly in
contact with the FML is considerably higher in the second condition.
Aqueous waste
liquid with
dissolved organics
FML
Aqueous waste
liquid with
dissolved organics
.......
<>-• • ;.•: Organic mixture;".«•'_ •*.
: '•':.'. -. .•»•....- .•••.•'
Condition 1
Condition 2
Figure 2-1. Two conditions that FMLs in contact with waste liquids or
leachates can encounter in waste containment units.
Cheremisonoff et al (1979) estimated that 90% by weight of industrial
hazardous wastes are produced as liquids and that these liquids contain
solutes in the ratio of 40% inorganic to 60% organic. Liquids as such can no
longer be placed in landfills; they must be treated to meet regulatory
criteria before final disposal (40 CFR 264.314).
In addition, hazardous wastes may have to
standards being developed by the EPA (40 CFR
Hazardous and Solid Waste Amendments of 1984
of untreated hazardous waste subject to land
specified dates. This statute requires the EPA
treatment, if any, which substantially diminish
substantially reduce the likelihood of migration of hazardous constituents
from the waste so that short-term and long-term threats to human health and
the environment are minimized" [Sec. 3004(m)(l)].
be treated to meet treatment
268, Subpart D). The RCRA
prohibit the land disposal
disposal restrictions beyond
to set "levels or methods of
the toxicity of the waste or
2-2
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The complex nature and variety of waste liquids greatly complicate
attempts to predict the effects on the performance of FMLs of their exposure
to the liquids present in waste containment units. At the present state of
knowledge, the short-term integrity (<20 years) of we!1-engineered lining
systems in properly operated containment units appears to be very good.
However, the long-term integrity of liner systems in actual service in
lined landfills has not been established. Interactions among the dissolved
constituents and their long-term effects on the components of in-service
lining systems, which are also subjected to various mechanical stresses, are
uncertain and the field experience that has been accumulated is limited.
Further results of actual field performance are necessary to assess the
long-term integrity of in-service lining systems. Interactions between
wastes and specific liner materials are discussed in Chapter 5. Long-term
service life is discussed in Chapters 5 and 6.
This chapter discusses waste liquids and leachates generated by solid
wastes and the dissolved constituents that are carried by these liquids
which may contact the liner systems in waste containment units. Data are
presented on the composition of hazardous waste leachates. Also discussed
are trends in the types of wastes and substances that are being contained in
land-based storage and disposal facilities. This chapter also describes the
basic types of waste liquids and hazardous substances that may require
secondary containment. It should be recognized that new regulations and
developments in treatment technology in the future will result in a decreased
volume of liquid wastes and in liquids of lower concentration which may
require storage or ultimate disposal. Appendix A presents data on the
composition of municipal solid waste (MSW) leachates and the composition of
wastes produced by various industries.
2.2 GENERAL DESCRIPTION AND CLASSIFICATION OF
LEACHATES AND WASTE LIQUIDS
The two types of liquids that may be present in a waste storage or
disposal unit are leachates and waste liquids. The type of waste present
will depend on whether the unit is one that contains a solid waste, e.g. a
landfill, or one that contains a liquid waste, e.g. a surface impoundment.
The following paragraphs describe the basic types of leachates and waste
liquids. Data are presented on the composition of actual hazardous waste
leachates.
2.2.1 Types of Leachates
In the context of waste management, leachate is the product of liquids
percolating through solid waste and dissolving soluble constituents of the
waste. The liquids that percolate through a waste come from three sources:
- Water from outside the containment unit, e.g. rainwater and surface
drainage.
- Liquids originally in the waste.
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- Liquids generated by the decomposition of the waste (particularly in
MSW landfills).
Figure 2-2 schematically presents the generation of leachate.
OVERBURDEN
PRESSURE
OUTSIDE WATER
(Rainwater, Drainage)
LIQUID PORTION OF
THE WASTE
WATER SOLUBLE
PORTION OF THE WASTE
WATER FROM
DECOMPOSITION
OF THE WASTE
SOLID WASTE!
LEACHATE COLLECTION
AND REMOVAL SYSTEM
DRAINAGE
TO SUMP
Figure 2-2. Sources of leachate generated by a solid waste.
The type of leachate produced by a landfill will depend on constituents.
Chian and DeWalle (1977) have shown that leachates are generally aqueous and
that dissolved organics and inorganics are present in only small quantities.
Depending on the composition of the waste, however, liquid organic phases may
be present.
Even though wastes containing free liquids are presently banned from
disposal in hazardous waste landfills, some liquids may still be disposed of
absorbed in solid wastes. The presence of free liquids in a waste is deter-
mined on a representative sample of the waste using the "Paint Filter Liquids
Test," EPA Method 9095 (EPA 1986a). In this test, the waste sample is placed
in a paint filter. If any liquid from the waste passes through and drops
from the filter within the 5-min. test period, the waste is deemed to contain
free liquids. Once solid waste has been placed in a containment unit, the
weight of the overlying materials can result in the separation of liquids
from the waste in which they had been absorbed.
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The dissolved constituents of the leachate may be either organic or
inorganic. The dissolved constituents, particularly some organic con-
stituents, can affect the properties of the polymeric components of a lining
system, just as the properties of clay soil liners can be affected by dis-
solved constituents at relatively low concentrations (Haxo and Dakessian,
1987).
2.2.2 Types of Waste Liquids
Waste liquids that are placed in surface impoundments fall into five
general types: aqueous-inorganic, aqueous-organic, aqueous-organic-inorganic,
organic, and sludges. These types are summarized in Table 2-1.
TABLE 2-1. TYPES OF WASTE LIQUIDS IN SURFACE IMPOUNDMENTS
Solvent or Solute or
Type
Aqueous-inorganic
Aqueous-organic
continuous phase
Water
Water
emulsified
Inorganic
Organic
liquid
Aqueous-organic-
inorganic
Organic
Sludges3
Water
Organic liquid
Water or organic liquid
Organic and inorganic
Organic
Organic and inorganic
aSludges contain significant amounts of suspended solids.
Aqueous-inorganic waste liquids are those in which water is the liquid
phase and the dissolved constituents are predominantly inorganic. Examples
of the dissolved constituents of these waste liquids include inorganic salts,
acids, bases, and trace metals. Examples of waste liquids in this category
are brines, electroplating wastes, metal-etching wastes, caustic rinse
solutions, and metal-cleaning liquids.
Aqueous-organic waste liquids are those in which water is the liquid
phase and the dissolved constituents are predominantly organic. Examples of
the dissolved components in this type of waste liquids are polar or charged
organic chemicals. Examples of wastes in this class are wood-preserving
wastes, water-based dye wastes, rinse water from pesticide containers, and
organic production wastes.
Of all the waste liquids that are stored in surface impoundments,
the most common are wastewaters that contain significant amounts of both
organic and inorganic species. These aqueous-organic-inorganic waste liquids
include wastewaters generated in industrial plants, e.g. chemical plants and
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petroleum refineries, which are held in surface impoundments prior to treat-
ment and disposal. Though not wastes, some in-process liquids may also be
considered aqueous-organic-inorganic liquids.
Organic waste liquids are those that have an organic liquid phase and
the dissolved constitutents are other organic chemicals dissolved in the
organic liquid. Examples of this type of waste liquids are oil-based paint
wastes, pesticide manufacturing wastes, spent motor oil, spent cleaning
solvents, and solvent refining and reprocessing wastes.
Sludges are the fifth type of waste liquids. They are generated when a
waste stream is dewatered, filtered, or treated for solvent recovery. They
are characterized by a high content of suspended solids which can consist of
such solids as clay minerals, silt precipitates, fine organic solids, or high
molecular weight hydrocarbons. Examples of sludges include water treatment
sludges, American Petroleum Institute (API) separator sludge, storage tank
bottoms, flue-gas desulfurization sludges, and filterable solids from any
production or pollution control process. After the placement of a sludge in
a waste storage facility such as a surface impoundment, solids and liquids or
leachates separate out of the sludge due to gravitational forces, agglomer-
ation, overburden pressures, and hydraulic gradients. These liquids are
similar in form to the first four types of waste liquids shown in Table
2-1, depending on the composition of the liquid phase and the dissolved
constituents.
2.2.3 Constituents of Leachates and Waste Liquids
Leachates and waste liquids generally consist of a liquid phase and
suspended solids. From the standpoint of FML permeability and durability,
the suspended solids are not a factor because they do not permeate an FML
and, in general, will not affect its durability. The liquid phase consists
of a principal liquid, dissolved organic liquids, dissolved organic solids,
dissolved inorganic solids, and/or suspended organic liquids. Figure 2-3
schematically presents a generalized composition of the liquid phase of a
waste. Even though the ratio of the constituents in an actual waste liquid
will vary greatly, water is generally the principal component and the carrier
of dissolved and suspended constituents. If water is the principal liquid,
then the organic and inorganic constituents will be dissolved in the water,
or, in the case of the organic liquids, be present in the water in emulsified
or suspended states. The liquid phase could also be an organic solution
containing dissolved organic liquids and solids and possibly some dissolved
inorganics.
The relative abundance of a given dissolved constituent depends on the
composition of the liquid phase. For example, if the liquid is a neutral
nonpolar organic, it will tend to dissolve other neutral nonpolar organic
chemicals. If the liquid phase is predominantly aqueous, it will tend to
dissolve only small quantities of nonpolar organics and relatively large
amounts of polar organics, some of which may be totally miscible with water.
Water can dissolve relatively large amounts of some inorganic acids, bases,
2-6
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and salts. Strong Inorganic acids and bases, which are invariably water-
based, may be particularly aggressive to some liner materials. (Note:
aqueous solutions with a pH less than or equal to 2 or greater than or equal
to 12.5 are prohibited from disposal in waste impoundments.)
LEACHATE AND OTHER
WASTE LIQUIDS
WATER
ORGANIC LIQUIDS
AND/OR ORGANIC
DISSOLVED SOLIDS
Examples:
• Organic Acids
• Oxygenated/
Heteroatomic
Hydrocarbons
• Habgenaled
Hydrocarbons
• Organic Bases
• Aromatic Hydro-
carbons
• Aliphatic Hydro-
carbons
INORGANIC
DISSOLVED
SOLIDS
Examples:
• Inorganic Acids
• Inorganic Bases
• Salts
• Trace Metals
Figure 2-3. Generalized composition of leachates and other waste liquids
that may contact a liner in service, showing the constituents
that may be present.
Some organic constituents of a leachate or waste liquid may affect the
properties of an FML or other components of a liner system because they may
be absorbed by the components and, as is discussed in Chapter 3, may be
highly mobile (Haxo, 1988). For the purpose of experimentally assessing the
effects of organics, the organic constituents of the leachate or liquid need
to be characterized in terms of the physical and chemical properties that
govern their interaction with the various components of the liner system.
The relative solubility parameters (Hildebrand and Scott, 1950; Haxo et al,
1988) of the organics and those of the respective liner system components are
useful in estimating potential level of interaction. The proximity in the
values of the solubility parameters of an organic, either neat, in solution,
or dispersed in water, to those of the respective compositions of the liner
2-7
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system components can affect the performance of the respective components.
When the solubility parameters of the organic and the specific component are
close, severe swelling and softening of that FML can occur. The use of
solubility parameters in assessing and predicting the compatibility of FMLs
and waste liquids is discussed in Chapter 5. The partitioning of dissolved
organics between water and FMLs and other polymeric components is also
discussed in Chapter 5.
Dissolved inorganic constituents of the waste liquid, such as salts, do
not swell FMLs and other geosynthetics and pipe and, generally, are not
factors in changes in properties of these components of a liner system on
exposure to these constituents in a waste liquid. Furthermore, these con-
stituents do not permeate the FML. On the other hand, as noted above,
extreme pH of the waste liquid can adversely affect some FMLs. Results of
immersion and exposure tests in leachates and waste liquids are presented and
discussed in Chapter 5.
2.2.4 Composition of Actual Hazardous Waste Leachates
Complete knowledge of the full composition of a liquid that would be in
contact with the lining system is desirable in assessing their compatibility.
Determining the full composition of a waste liquid or leachate involves
identifying the many constituents present in that liquid. Analysis of a
waste liquid is usually performed to determine whether or not it is hazardous
by ascertaining whether or not specific chemical species identified by the
EPA as hazardous are present. In both the "Extraction Procedure (EP) Tox-
icity Test Procedures" (EPA, 1985), and the "Toxicity Characteristic Leach-
ing Procedure" (TCLP) (EPA, 1986c), the extracts are analyzed for specific
constituents. The number and quantity of organic constituents identified by
procedures such as these may only yield a minor fraction of the total number
and amount of constituents that are actually dissolved in a leachate or waste
liquid. The total organic content of a waste liquid can be estimated by
determining the total organic carbon (TOC) content which includes both
hazardous and nonhazardous organic species. The latter species, which may
be considerably greater in number than the organics specifically identified
as hazardous, are often not identified. This lack of information of the
complete composition of a leachate necessitates the compatibility testing of
a liner system component with a representative sample of the leachate or
other waste liquid to be contained.
This subsection presents data on the composition of hazardous waste
leachates. Data on the composition of MSW leachates and various industrial
wastes are presented in Appendix A.
To develop more complete data on the composition of hazardous waste
leachates with the hope of developing a generic leachate, Bramlett et al
(1987) performed standard analyses of leachates from actual hazardous waste
facilities to determine the pollutants present. In this study, leachates
were collected from 13 hazardous waste landfills in different parts of the
continental United States. Individual samples were collected for each
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analysis in accordance with EPA sample collection protocols; the samples
were protected from the time of collection to the time of analysis to pre-
vent loss of volatile constituents and changes in their character due to
oxidation. A preservative, if needed, was added to each container. For
example, nitric acid was added to samples for metals analyses and sodium
hydroxide was added to samples for cyanide analyses. All samples were stored
at 4°C until analyzed.
Analyses of the leachates were performed for:
- 35 volatile priority pollutants.
- 68 semi volatile priority pollutants.
- 13 metals.
- 102 nonpriority pollutants, which were identifiable based on the
library spectra on hand (Bramlett et al, 1987).
Analyses included tests for the following constituents and parameters on each
of the leachate samples:
- Volatile organics.
- Semivolatile organics, including base/neutrals and acid extractables.
- Heavy metals.
- Cyanide.
- Chemical oxygen demand (COD).
- Total organic carbon. (TOC).
Analyses for volatile and semi volatile organics were performed in accordance
with EPA Methods 624 and 625 (EPA, 1984a; EPA, 1984b). Trace metals, cya-
nide, COD, and TOC analyses were performed in accordance with the EPA guide-
lines presented in "Methods for Chemical Analysis of Water and Wastes" (EPA,
1983), as modified in the EPA Contract Laboratory Program protocol; specific
methods are listed in Table 2-2. Gas chromatography followed by gas chro-
matography/mass spectroscopy (GC/MS) was used to identify volatile organics
within three days after receipt of the samples by the laboratory. Semi-
volatile organics (base/neutral and acid extractables) were analyzed within
42 days after arrival at the laboratory.
The results of the analyses for metals, pH, redox potential (Eh),
electrical conductivity (EC), total cyanide, TOC, and COD are summarized in
Table 2-3 (Bramlett et al, 1987, p 58). The results presented in Table 2-4
(Bramlett et al, 1987, p 60) show the percentage of TOC in the leachate
samples accounted for by the analyses for the individual organics.
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TABLE 2-2. METHODS USED TO ANALYZE LEACHATE SAMPLES
Fraction analyzed
Federal Register^ EPA 600/4-79-020^ SW-846C
Volatile organics
Semi volatile organics
(base/neutral and
acid extractables)
Heavy metals:
Antimony
Arsenic
Beryllium
Cadmi urn
Chromium
Copper
Lead
Mercury
Nickel
Selenium
Silver
Thailium
Zinc
Cyanides
Chemical oxygen
demand (COD)
Total organic
cabon (TOC)
Method 624
Method 625
Method
Method
Method
Method
Method
Method
Method
Method
Method
Method
Method
Method
Method
204.
206.
210.
213.2
218.
220.
239.
245.
249.
270.
272.2
279.2
289.2
7041
7060
7091
7131
7191
• * •
7421
7470
7740
7841
Method 335.2
Method 410
Method 415.2
9060
^Federal Register, October 26, 1984, 40 CFR Part 136 (EPA, 1984a; EPA 1984b).
bEPA 600/4-79-020, updated March, 1983 (EPA, 1983).
cSW-846, 3rd ed. (EPA, 1986a).
Source: Bramlett et al, 1987.
Overall, it was found that the leachates were approximately 99% water
and <1% (<10,000 mg/L) organic by weight. Of the total TOC obtained by the
analyses, only 4% (i.e. <400 ppm of the leachate) was characterized. Of the
4% characterized organic carbon, 39% was organic acid, 35.8% was oxygenated/
hetroatomic hydrocarbons, 11% was halogenated hydrocarbons, 7.2% was organic
bases, 6% was aromatic hydrocarbons, and 0.9% was aliphatic hydrocarbon.
Thus, the standard EPA leaching procedure (EPA, 1986a) and analytical tests
fall far short of identifying all of the organics in a leachate, some of
which might partition to the FML and other liner system components and, over
an extended period of time, affect the performance of these materials. With-
in the 96% of the unknown carbon there may be organics (such as halogenated,
2-10
-------
TABLE 2-3. STATISTICAL DATA FOR METALS, pH, Eh, CONDUCTIVITY, TOTAL CYANIDE, TOC, AND COD
ro
Range of detected
constituent
Parameter
Metal3
Silver
Arsenic
Be ryl 1 i urn
Cadmi urn
Ch romi urn
Copper
Mercury
Nickel
Lead
Antimony
Selenium
Thallium
Zinc
pHb
Ehb (volts)
Conductivity^ (ymhos/cm)
Temperature^ (°C)
Total Cyanide0 (mg/L)
CODC (mg/L)
TOCC (mg/L)
Minium
0.3
458
0.2
0.7
0.2
2.3
45
17.3
0.3
13
221
9.4
5.12
7.1
0.343
4,250
19.9
0.01
1,950
195
Maximum
32.8
129,600
7.4
102
1,734
17,030
39,300
67,110
1,006
5,240
3,488
156
24,510
9.3
0.093
12,000
32
55
23,300
11,750
Mean
6.55
13,097.08
0.81
18.74
280.54
1,885.07
4,973.04
6,416.95
115.58
522.35
1,167.88
36.92
2,512.77
8.2
0.226
14,694
26.7
9.93
10,217
3,097
Standard
deviation
9.56
33,848.32
1.96
28.25
558.80
4,525.28
10,308.36
17,609.15
263.09
1,367.79
890.25
45.62
6,403.20
0.857
0.126
6,588
6.2
17.85
6,475
3,071
Number of
sites where
constituent
was detected
13
10
6
13
13
13
12
13
13
11
13
11
13
• • •
• • •
• • •
• • •
9
• • •
• • •
Mean
mole
fraction,
xlOO
0.0249
31.9456
0.0904
0.1572
2.2826
13.0760
0.0101
22.5979
0.3740
3.9792
16.9132
0.1223
8.4268
100
• • •
• • •
• * •
• • •
• • *
• • •
• • •
aMetal data is in yg/L (except for Hg, which is in ng/L).
bStatistical data does not include sites where no measurements were taken,
CA11 samples were analyzed for total cyanide, TOC, and COD.
Source: Bramlett et al, 1987, p 58.
-------
TABLE 2-4. PERCENT OF TOCa CONTENT ACCOUNTED
FOR BY ANALYSIS OF LEACHATES FOR POLLUTANTS
Hazardous
waste
site
1
2
3
4
5
6
7
8
9
10
11
12
13
TOG*,
mg/L
2,343
2,004
2,278
718
195
1,579
1,048
11,750
309
4,078
4,909
6,602
2,453
"Priority"
Volatile
1.734
1.565
0.1886
0.659
34.4
0.167
1.90
0.00393
20.98
2.075
1.995
1.510
0.314
pollutants, %
Semi volatile
2.86
0.876
3.94
0.604
1.137
2.392
2.20
0.743
18.12
1.718
3.06
1.551
1.049
"Nonpriority"
pollutants, %
2.176
5.86
1.951
0.2917
4.89
0.487
1.939
0.1820
20.41
0.468
0.500
0.3520
1.020
Total ,
%
6.77
8.30
6.08
1.55
40.43
3.05
6.04
0.93
59.51
4.26
5.56
3.41
2.38
aTotal organic carbon.
Source: Bramlett et al, 1987, p 60.
aliphatic, and aromatic hydrocarbons) that could have a significant impact on
the performance of a liner. On the other hand, in some cases much of the
unidentified carbon may arise from humic acid, lignin, and other organics
which would not be absorbed and affect the liner and other components of the
liner system.
In view of the small fraction of the organic carbon that was actually
identifiable, a subsequent study was conducted by McNabb et al (1987). In
this study, a more rigorous and complex analytical methodology was devel-
oped than was used in the study by Bramlett et al (1987). A hazardous waste
sample was analyzed with the objective of maximizing the percentage of TOC
accounted for by specific species or by functional groups. This method
2-12
-------
was applied to a single hazardous waste leachate sample to yield, in the
initial step, the results presented in Table 2-5. In the subsequent step,
approximately 48% of the 16,000 mg/L TOC was accounted for. Of this amount,
20% was attributed to individual species and 28% to functional groups.
Results of the analyses by McNabb et al (1987) are presented in Table 2-6.
The same analytical protocol is being used to determine the complete compo-
sition of two additional waste liquids (McNabb et al, 1987).
TABLE 2-5. INITIAL CHARACTERIZATION OF A HAZARDOUS WASTE LEACHATE
Analyte Units Field blank Sample average
Nitrogen (total)
Sulfate
Sulfide
Methyl ene blue active substances
mg/L <10
mg/L <3
mg/L <10
mg/L <0.1
635
210
<10
<0.1
pH
Conductivity
Total organic carbon
Total organic halides
...
ymho/cm
mg/L
mg Cl/L
6.9
10
<3
0.07
4.3
19,500
16,000
166
Source: McNabb et al (1987).
One objective of the work by McNabb et al (1987) was to develop formu-
lations for synthetic leachates which can be used in compatibility testing.
The development of a procedure to determine the composition of a waste
liquid, particularly the concentration of the major organic constituents of
the leachate, would be useful in developing predictive methods for assessing
the compatibility of an FML with a waste, based on their respective compo-
sitions. Work described in Chapter 5 shows that some organics partition more
to some FMLs than do others. This tendency of some organics will be dis-
cussed in that chapter in connection with the use of solubility parameters in
assessing and predicting compatibility and in the distribution of dissolved
organics between water and polymeric materials.
2.3 CHARACTERIZING HAZARDOUS WASTES AND WASTE CONSTITUENTS
To meet RCRA requirements regarding management and disposal of solid
wastes, a generator or handler of a waste must determine whether the waste
being generated or handled is hazardous and toxic. He has two methods of
2-13
-------
TABLE 2-6. TOTAL ORGANIC CARBON CONTENT IDENTIFIED
BY CHEMICAL CLASSIFICATION
Chemical classification
Organic acids
Oxygenated hydrocarbons
Halogenated hydrocarbons
Fraction
of total
TOC by
weight, % Representative compounds
20.3 Benzoic acid (17.1%)
Phenol (3.1%)
Alkanoic acids (0.13%)
Substituted benzoic
acids (0.01%)
Substituted phenols
(0.002%)
0.8 Ketone solvents
(0.0003%)
Alcohols (0.0002%)
Trimethylpentanediol
(0.8%)
0.86 Total organic halides
(TOX) (0.86%)
Chlorinated solvents
(0.001%)
TOC in
leachate,
mg/L
2736.0
496
20.8
1.6
0.32
0.048
0.032
128.0
137.6
0.16
Organic bases
Aromatic hydrocarbons
Aliphatic hydrocarbons
0.0 None detected
26.8 Aromatic compounds
>500 MWa (26.8%)
Benzene and alkyl-
substituted benzenes
(0.001%)
0.002 n-Alkanes (0.002%)
9MW = Molecular weight.
Source: McNabb et al (1987).
4288
0.16
0.32
2-14
-------
determining whether the solid waste he is managing is hazardous (EPA, 1986d);
he can either:
- Use a list of wastes which the Environmental Protection Agency (EPA)
has identified as hazardous (40 CFR 261, Subpart D), or
- identify a solid waste as hazardous on the basis of certain measur-
able characteristics, i.e. ignitability, corrosivity, reactivity, or EP
toxicity, that are defined by the EPA (40 CFR 261, Subpart C).
To determine whether or not a hazardous waste exhibits the character-
istic of toxicity, the waste is leached in accordance with the EP Toxicity
Test Procedure (EPA, 1985) and analyzed to determine the concentration of 14
constituents, including 8 metals, and 4 insecticides, and 2 herbicides. The
waste is deemed to have the characteristic of EP toxicity (and thus is
"hazardous") if the concentration of any of the 14 contaminants is greater
than the maximum concentration values listed in 40 CFR 261.24 (EPA, 1986d).
In addition, analyses can be performed on the extract for a series of
"priority pollutants" which, as noted above, generally cover only a fraction
of the potential organics that are present in the waste. The EP toxicity
characteristic and the EP method itself both have major shortcomings. The
toxicity characteristic is the only characteristic that relates to the
toxicity of a waste not identified on the list of hazardous wastes in 40 CFR
251, Subpart D. It accounts for only a small fraction of the total list of
hazardous constituents identified in Appendix VIII of 40 CFR 261 (EPA,
1986d). Analyses to determine the EP toxicity characteristic of a waste give
no information on the concentrations of constituents, specifically organics,
that can affect the properties and performance of the polymeric components of
a lining system. The shortcoming of the EP method itself is that the pro-
cedure was optimized to evaluate the leaching of inorganic rather than
organic constituents. In 1984 HSWA directed the EPA to amend both the EP
toxicity characteristic and the EP method [Section 3001(g) and (h)].
As an alternative to the EP method, the EPA has developed the "Toxicity
Characteristic Leaching Procedure" (TCLP), which has been published as an
appendix to a final rule (EPA, 1986c). This procedure is presently (May
1988) being used as one method of verifying whether or not a restricted waste
or the residue resulting from treatment of a restricted waste can be legally
land disposed without further treatment. One advantage of this procedure
over the EP procedure is the requirements for preventing the loss of vol-
atiles during leaching. The constituents for which the wastes are analyzed
depend on the type of waste being extracted. For example, spent solvent
wastes (EPA waste numbers F001 through F005) are analyzed for 25 constituents
[40 CFR 268, Subpart D (EPA, 1986d)].
The EPA has proposed amending the EP toxicity characteristic by replac-
ing the EP method with the TCLP and by expanding the characteristic to
include 38 additional constituents, including a number of organics (EPA,
2-15
-------
1986e). In spite of the increased number of organics that are analyzed in
the toxicity characteristic tests, these procedures do not analyze for all
organics that may be present. Though some organics on the proposed list may
affect polymeric materials, many that are not on the list can also affect the
performance of the polymeric components of a lining system.
2.4 IMPACT OF CURRENT AND FUTURE WASTE MANAGEMENT PRACTICE
ON THE COMPOSITION OF WASTES AND WASTE LIQUIDS THAT ARE
STORED OR DISPOSED OF ON LAND
In the early 1970s, discussion of hazardous wastes focused on the
trace metal constituents which potentially could leach into the groundwater.
Other discussion focused on containment research, development, and planning,
and on the use of barrier materials to control the movement of these in-
organic constituents. At that time, the use of clay lining materials was
emphasized. Subsequently, considerable research and development has been
performed to assess the effectiveness of polymeric materials as barriers to
prevent the migration of inorganics (Haxo et al, 1985).
During the past decade, the focus has shifted toward the organic
constituents which are, in some cases, more mobile and have caused pollution
both of the groundwater and the air. Because of the toxic qualities of many
organics, efforts have been made to improve the design and construction of
waste containment units to reduce and, if possible, prevent the migration of
organics out of these units.
In view of uncertainties about the effectiveness of land disposal
over long exposure periods, considerable emphasis is being placed on the
minimization of wastes containing hazardous constituents, on the land dis-
posal restriction of specific wastes and wastes containing concentrations of
specific waste constituents, and on the treatment of restricted wastes so
that, once treatment standards are met, these wastes can be legally land
disposed. However, even with waste minimization as a national policy, there
will still be wastes requiring land disposal, including:
- Residuals from stabilization/solidification processes.
- Residuals from incineration, e.g. ash and wastewater.
- Residues from various waste treatment processes other than inciner-
ation and solidification/stabilization technology processes.
- Soils from spills of hazardous substances or wastes, the composition
of which could vary greatly.
- Contaminated material from cleanups under the Comprehensive Environ-
mental Response, Compensation, and Liability Act (Superfund) (CERCLA)
including petroleum products and the wide range of hazardous materials
that are listed in EPA rules (EPA, 1986d).
2-16
-------
Minimization, land disposal restrictions, and treatment of hazardous wastes
to achieve treatment standards can result in lower concentrations of some
organics that might be in contact with components of a lining system and thus
reduce the potential effects of a leachate or waste liquid on the liner
system (Breton et al, 1987; McArdle et al, 1987). Some of the current waste
management strategies that affect the composition of wastes and their
disposal on land are briefly discussed in the following sections.
2.4.1 Waste Minimization by Recycling and Source Reduction
Through the enactment of RCRA and HSWA, Congress has established the
minimization of waste generation as a national policy. Waste minimization is
defined as the reduction, to the extent feasible, of hazardous waste that
is generated or subsequently treated, stored, or disposed of (EPA, 1986f).
It includes any waste management practice that results in either: (1) the
reduction of total volume or quantity of hazardous waste, or (2) the reduc-
tion of toxicity of hazardous waste, or both, so long as the reduction is
consistent with the goal of minimizing present and future threats to human
health and the environment. Overall issues and options in waste minimization
are discussed in a report by Versar, Inc. and Jacobs Engineering Group
(1986).
In accordance with HSWA, EPA is establishing a waste minimization
program to comply with the waste minimization policy.
There are three basic methods of minimizing wastes (EPA, 1986f):
- Source reduction, which refers to the reduction or elimination
of waste generation at the source, usually within a process; source
reduction can include process modifications, substitutions in feed-
stocks or improvements in purity, increased efficiency in a process,
or recycling within the process. Source reduction implies any action
that reduces the amount of waste exiting from a process.
- Recycling or reusing a waste as a substitute for a commercial product,
or as an ingredient or feedstock in an industrial process. It also
refers to the reclamation of useful constituent fractions within a
waste material or removal of contaminants from a waste to allow it to
be reused.
- Waste treatment, including such technologies as incineration, chemical
detoxification, biological treatment, etc. Some of these technologies
are discussed separately below.
It should be noted that dilution is prohibited as a means of treating a
restricted waste or the residual from treatment of a restricted waste in
order to achieve compliance with 40 CFR 268, Subpart D [40 CFR 268.3 (EPA,
1986b)].
2-17
-------
Even without mandatory requirements, there are strong incentives for
waste generators to proceed with waste minimization. Some of the major
incentives are (EPA, 1986f):
- Increased cost of waste disposal, as a result of recent requirements
of HSWA.
- Difficulties in siting new waste containment units.
- Permitting burden and corrective action requirements.
- Financial liability of hazardous waste generators.
- General favorable public attitude toward waste minimization.
Of particular importance from the standpoint of liner performance and
service life is the minimization of wastes containing organic solvents and
other organics that can adversely affect liner properties. In recent years
there has been a significant reduction in the volume of solvent wastes
produced, including both halogenated and nonhalogenated solvents. At the
present time approximately 24% of these former wastes are being recycled.
In the last four years there has been a 30% drop in waste generation by the
chemical industry, even though at the same time there has been an increase
in production (Chemical Week, 1987).
2.4.2 Incineration of Wastes
Incineration is generally considered to be a well demonstrated tech-
nology for the treatment of organic hazardous wastes including spent solvent
wastes. However, incineration does produce residues, i.e. the off gas, ash,
and scrubber wastewater, each of which must be managed in an environmentally
sound manner. The ash can be landfilled either as such or after treatment.
The wastewater must be treated before final disposal. The wastewater is
usually generated in stack cleaning of the gases from the incineration. In
both the ash and the wastewater there is a potential for organics that have
not been completely oxidized. This potential was shown in an experiment
conducted by Boegel (1987) in which residues generated in two incineration
systems that burned RCRA wastes were evaluated. One system was a commercial
treatment storage and disposal facility that accepted organic wastes from a
variety of industrial generators, and the second operated on site at a
chemical manufacturing plant. Both generated two types of residue: ash and
scrubber wastewater. The ash from both facilities was landfilled. The
scrubber wastewater from one facility resulted in a metal sulfide sludge; the
wastewater from the other was neutralized and injected into a deep well. The
ash of one exhibited extremely high concentrations of tetrachloroethylene,
as is shown in Table 2-7. Tables 2-7 through 2-9 present data on the
analyses of residues from the incineration of selected wastes (Boegel,
1987).
A properly functioning incinerator should burn the solvents completely,
i.e. at a destruction and removal efficiency (ORE) of 99.99%; but, even when
2-18
-------
TABLE 2-7. FACILITY A ASH ANALYTICAL DATA9 - ORGANICS
Proposed toxicity
Compositional, TCLP extract, characteristic
Parameter
Volatile organics
Methyl ene chloride
Acetone
Chloroform
2-Butanone
1,1,1-Trichloroethane
1,2-Dichloropropane
Trichl oroethyl ene
Benzene
4-Methyl -2-pentanone
Tetrachl oroethyl ene
Toluene
Chlorobenzene
Ethyl benzene
Styrene
Xylenes
Methanol
vg/kg
38,000
20,000
46
2,000
12
32
120
42
2,300
1,200,000
2,500
27
380
320
1,900
410,000
yg/L
8,800
<3,300
<1,700
<3,300
<1,700
<1,700
<1,700
<1,700
<3,300
48,000
11,000
<1,700
<1,700
<1,700
<1,700
• • •
levelb, yg/L
8,600
none
70
7,200
30,000
none
70
70
none
100
14,400
1,400
none
none
none
none
Semi volatile organics
Phenol
Nitrobenzene
2,4-Dimethyl phenol
Naphthalene
2-Nitroaniline
Dimethyl phthalate
Di ethyl phthalate
Di-n-butyl phthalate
40,000
29,000
23,000
24,000
180,000
55,000
120,000
160,000
<1,400
<200
<1,000
310
1,300
370
410
<200
14,400
130
none
none
none
none
none
none
aAnalysis of a single composite sample. Aliquots of ash making up
the composite were collected every two hours during the incineration
run.
^Proposed level of the constituent in the extract obtained by the TCLP
for determining whether or not the extracted waste is toxic, i.e. whether
or not the waste is hazardous (EPA, 1986e).
Source: Boegel, 1987.
2-19
-------
TABLE 2-8. FACILITY A ASH ANALYTICAL DATAa - METALS
Compositional ,
Parameter mg/kg
Toxic metals
Antimony
Arsenic
Barium
Beryllium
Cadmium
Hexavalent
Chromium
Total Chromium
Copper
Lead
Mercury
Nickel
Selenium
Silver
Thai lium
Zinc
Other analyses
Total solids,
(mg/kg)
Specific gravity,
(9/mL)
Paint filter
test
8.0
42.0
150
<0.2
2.0
0.083
71.0
13,800
30.0
0.2
190
<1.0
0.4
2.0
280
599,300
1.2809
Pass
TCLP extract, EP extract,
mg/L mg/L
0.094 <1.0
0.062 0.2
0.026 <1.0
<0.005 <0.2
0.02 <0.5
...
0.01 <0.3
0.729 4.0
<0.05 <1.0
0.00025 <0.1
1.14 2.0
<0.001 <1.0
<0.005 <0.2
<0.001 <1.0
1.15 0.3
... ...
...
EP toxicity
characteristic
levelb, mg/L
none
5.0
100.0
none
1.0
none
5.0
none
5.0
0.2
none
1.0
5.0
none
none
...
...
aAnalysis of a single composite sample. Aliquots of ash making up the
composite were collected every two hours during the incineration run.
b40 CFR 261, Subpart C (EPA, 1986d).
Source: Boegel, 1987.
2-20
-------
TABLE 2-9. FACILITY B ASH ANALYTICAL DATA - METALS
Asha
Compositional
Parameter mg/kg
Toxic metals
Antimony
Arsenic
Barium
Beryllium
Cadmium
Hexavalent
Chromium
Total Chromium
Copper
Lead
Mercury
Nickel
Selenium
Silver
Thallium
Zinc
Other analyses
Total solids
Total dissolved
solids (mg/kg)
Total suspended
solids (mg/kg)
Total organic
halide (wt %)
Total chlorine,
(wt %)
Silica (wt %)
Specific gravity
(g/mL)
PH
14.5
<0.1
75
<0.2
<0.5
0.05
361
4,600
340
1.6
4,200
<1
<0.2
<1
1,160
811,000
• • •
• • •
• • •
• • •
17.77
1.9363
• • •
TCLP EP toxicity Scrubber
, extract, characteristic wastewaterc,
mg/L levelb, mg/L mg/kg
0.03
0.004
0.39
0.002
0.01
<10
0.085
96
0.56
0.004
34
<0.05
<0.005
<0.001
25
• • •
• • •
• • •
• • •
• • •
• • •
• • •
• • •
none
5.0
100.0
none
1.0
none
5.0
none
5.0
0.2
none
1.0
5.0
none
none
• • •
• • •
• • •
• • •
• • •
• • •
• • •
• • •
<1
<0.1
2
<0.2
<0.5
0.2
1.5
241
106
<0.1
27
<1
0.2
<1
363
3867
3500
67
0.08
1.59
• • •
0.9936
0.7
aEach value represents the average of 6 grab samples,
b40 CFR 261, Subpart C (EPA, 1986d).
°Each value represents the average of 3 grab samples,
Source: Boegel, 1987. ? p.
-------
an incinerator is functioning properly, it will probably produce ash that
will need to be landfilled. Landfills will remain necessary because wastes
other than pure solvents contain noncombustible constituents, e.g. metals,
soils, silicates, that produce solid residue.
2.4.3 Restrictions on the Type of Wastes
The EPA is gradually restricting the amounts and types of organics that
can be landfilled and has set up a schedule for action on the prohibition of
land disposal of untreated hazardous wastes and the establishment of treat-
ment standards [40 CFR 268 (EPA, 1986b: EPA, 1987)]. These restrictions can
limit the concentrations of constituents that may significantly affect the
properties of varius components of the lining system. For instance, reducing
the volatile halogenated organics, which are generally highly mobile, will
reduce the potential for absorption and swelling of FMLs and thus the
potential for changes in the physical properties and permeability of the
FMLs. The effect of reduced concentration of such constituents in a waste
liquid is discussed in Chapter 5 with particular reference to the partition-
ing of organics between water and FMLs.
2.4.4 Application of Solidification/Stabilization Technologies
The concentration and mobility of organics and other waste constituents
in a waste can be reduced through the application of one of the solidifi-
cation/stabilization technologies (S/S). These methods of treating waste
liquids and hazardous residues from various treatment technologies have been
used for more than 20 years to manage industrial wastes prior to land dis-
posal. These technologies employ selected materials (e.g. portland cement,
fly ash, lime, etc.) to alter the physical and chemical characteristics of a
waste to reduce the mobility of pollutants when disposed of on land.
A great variety of processes have been developed, and many are in use
(Conner, 1984). In general terms, S/S, as it relates to managing hazardous
wastes, refers to technologies in which additives are used to transform a
waste into a more manageable or less toxic form by physically immobilizing
and/or chemically fixating the waste constituents. Various terms are used
with respect to these technologies which are important to define. However,
the definitions for S/S technologies vary depending upon their source. The
following definitions are used by the EPA (Wiles, 1986; Cullinane et al,
1986) in describing these processes:
- Solidification. A process in which materials are added to a liquid
or semi liquid waste to produce a solid is referred to as solidi-
fication. It may or may not involve a chemical bonding between the
toxic contaminant and the additive.
- Stabilization. Stabilization refers to a process by which a waste
is converted to a more chemically stable form. The term includes
solidification, but also includes use of a chemical reaction to
transform the toxic component to a new non-toxic compound or sub-
stance. Biological processes, however, are not considered.
2-22
-------
- Chemical Fixation. Chemical fixation implies the transformation of
toxic contaminants to a new non-toxic form. The term has been misused
to describe processes which did not involve chemical bonding of the
contaminant to the binder.
- Encapsulation. Encapsulation is a process involving the complete
coating or enclosure of a toxic particle or waste agglomerate with a
new substance, e.g. the S/S additive or binder. Microencapsulation
is the encapsulation of individual particles. Macroencapsulation is
the encapsulation of an agglomeration of waste particles or micro-
encapsulated materials.
Even though wastes containing constituents that have been classified as
hazardous have been stabilized, they may still release or leach these
constituents at reduced concentrations. These wastes may need to be sub-
jected to leaching tests to determine whether or not the stabilized waste
meets treatment standards [40 CFR 268, Subpart D (EPA, 1986b)].
2.4.5 Miscellaneous Possible Hazardous Wastes
Additional wastes presently disposed of on land may eventually be listed
as hazardous wastes and require disposal in hazardous waste landfills. Two
such wastes include:
- Muncipal solid wastes and residues from the incineration of these
wastes.
- Coal-fired power plant residues, e.g. fly ash and flue-gas desul-
furization sludges.
Even though constituents of these wastes probably would not significantly
affect the polymeric components of the FMLs, listing these wastes as haz-
ardous would significantly affect the total required disposal capacity of
hazardous waste landfills. The effects of exposing a wide range of FMLs to
these wastes is discussed in Chapter 5.
2.5 DESCRIPTION OF WASTES FROM SPECIFIC SOURCES
The discussion on wastes in the above sections has been both general and
specific as it relates to the composition of the leachates or other waste
liquids that may contact liner materials in service. A general discussion
on hazardous wastes and their distribution in their United States can be
found in EPA's Report to Congress (EPA, 1974), the report of the Chemical
Manufacturers Association (1985), and the National Research Council/National
Materials Advisory Board (1983). Data on wastes from various sources,
including municipal solid wastes, industrial wastes, electric power plant
wastes, mining wastes, and uranium tailings are presented in Appendix A.
Examples of the composition of specific wastes from the following industries
are presented in that appendix:
- Electroplating and metals finishing industry.
2-23
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- Inorganic chemicals industry.
- Metal smelting and refining industry.
- Organic chemicals industry.
- Paint and coatings formulating industry.
- Pesticide industry.
- Petroleum refining industry.
- Pharmaceutical industry.
- Pulp and paper industry.
- Rubber and plastics industry.
- Soap and detergent industry.
- Coal-fired electric power industry.
Many of the wastes generated by these industries contain free liquids which,
under current statutes and rules, must be treated before ultimate disposal
to reduce leachate formation and immobilize or destroy potential polluting
species. Examples of various treatments are described in Sections 2.4.2
and 2.4.4.
2.6 HAZARDOUS SUBSTANCES IN STORAGE FACILITIES REQUIRING
SECONDARY CONTAINMENT
In addition to being used in storage and disposal facilities, FML lining
systems are also being used for secondary containment of both aboveground and
underground tanks that contain various hazardous substances. The function
of a liner system for secondary containment is to prevent the migration of a
liquid that may be released from a leaking tank or pipe until a repair can be
made.
Ninety-eight to 99% of the liquids that are stored in underground
storage tanks are petroleum products (Lysyj, 1987), such as gasoline, diesel
fuel, crude oil, and lubricating oils. The remaining 1 to 2% are organic
solvents of various types, as is shown in Table 2-10. Underground storage
tanks are also being used for the storing of CERCLA wastes prior to disposal.
In all cases, the liquids that are being stored are principally organics,
many of which are solvents and pure liquids. In secondary containment
applications, however, a liner is not in contact with the liquid for great
lengths of time, although it may have to be in service in the ground for
relatively long periods of time.
2-24
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TABLE 2-10. PREDOMINANT TYPES OF ORGANIC
CHEMICALS STORED IN UNDERGROUND STORAGE TANKS
Organic chemical
California
Number Volume
of of
tanks, tanks,
New York
Number Volume
of of
tanks, tanks,
Chemical
Manufacturers
Association
Number Volume
of of
tanks, tanks,
Solvents:
Ketones/aldehydes
Aromatic hydrocarbons
Alcohols
Chlorinated hydrocarbons
Esters
Al i cyclic hydrocarbons
Total
Monomers
Miscellaneous chemicals
Pesticides
35.6
22.2
10.2
12.5
6.0
0.6
87.1
3.6
7.4
1.4
32.9
21.1
8.8
14.0
4.4
0.7
81.9
6.2
7.0
4.2
25.2
37.8
16.5
5.7
6.2
• • •
91.4
2.8
6.0
...
31.5
32.9
17.2
4.0
4.4
• • •
90.0
1.6
8.0
...
23.5
21.8
18.8
12.6
1.2
0.4
78.3
13.3
8.8
...
21.7
22.3
16.8
10.3
0.8
0.4
72.3
22.2
5.0
...
Note: Totals may not add up to 100% because of rounding.
Source: Lysyj, 1987.
2.7 REFERENCES
Boegel, J. V. 1987. Assessment of Residues from Incineration of RCRA
Wastes. In: Proceedings of the 13th Annual Research Symposium. EPA/
600/9-87/015. U.S. Environmental Protection Agency, Cincinnati, OH. pp
262-282.
Bramlett, J. A., C. Furman, A. Johnson, W. D. Ellis, H. Nelson, and W. H.
Vick. 1987. Composition of Leachates from Actual Hazardous Waste
Sites. U.S. Environmental Protection Agency, Cincinnati, OH. 113
pp.
Breton, M., M. Arienti, P. Frillici, M. Kravett, S. Palmer, A. Shayer,
and N. Surprenant. 1987. Technical Resource Document: Treatment
Technologies for Solvent Containing Wastes. EPA/600/2-86/095 (NTIS PB
87-129 821/AS). U.S. Environmental Protection Agency, Cincinnati,
OH.
2-25
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Chemical Manufacturers Association. 1985. Hazardous Waste Survey. Chemical
Manufacturers Association, Washington, D.C.
Chemical Week. 1987. Hazardous Waste: Minimization Eases the Cleanup.
Vol. 141, No. 8, August 19, 1987.
Cheremisonoff, N., P. Cheremisonoff, F. Ellerbusch, and A. Perna. 1979.
Industrial and Hazardous Wastes Impoundment. Ann Arbor Science Publish-
ers, Ann Arbor, MI. 475 pp.
Chian, E. S. K., and F. B. Dewalle. 1977. Evaluation of Leachate Treat-
ments. 2 Volumes. EPA-600/2-77-186 a,b. U.S. Environmental Protection
Agency, Cincinnati, OH.
Conner, J. R. 1984. The Modern Engineered Approach to Cheinical Fixation and
Solidification Technology. In: Proceedings of National Conference on
Hazardous Waste and Environmental Emergencies. Hazardous Materials
Control Research Institute, Silver Spring, MD. pp. 293-298.
Cullinane, M. J., Jr., L. W. Jones, and P. G. Malone. 1986. Handbook for
Stabilization and Solidification of Hazardous Wastes. EPA 540/2-86-001.
U.S. Environmental Protection Agency, Cincinnati, OH.
EPA. 1974. Report to Congress: Disposal of Hazardous Wastes. SW-115.
U.S. Environmental Protection Agency, Washington, D.C. 110 pp.
EPA. 1983. Methods for Chemical Analysis of Water and Wastes. EPA 600/
4-79-020, updated March 1983. U.S. Environmental Protection Agency,
Washington, D.C.
EPA. 1984a. EPA Method 624. Purgeables. Federal Register, Vol. 49, No.
209. October 26, 1984. 40 CFR Part 136. U.S. Government Printing
Office, Washington, D.C.
EPA. 1984b. EPA Method 625. Base/Neutrals and Acids. Federal Register,
Vol. 49., No. 209. October 26, 1984. 40 CFR Part 136. U.S. Government
Printing Office, Washington, D.C.
EPA. 1985. Extraction Procedure (EP) Toxicity Test Procedures, Procedure
A. 40 CFR Part 261, Appendix II. U.S. Government Printing Office,
Washington, D.C. See also: Method 1310. In: EPA. 1986. Test Methods
for Evaluating Solid Wastes. SW-846. 3rd ed. U.S. Environmental
Protection Agency, Washington, D.C. September 1986.
EPA. 1986a. Test Methods for Evaluating Solid Wastes. SW-846. 3rd
ed. U.S. Environmental Protection Agency, Washington, D.C. September
1986.
EPA. 1986b. Hazardous Waste Management Systems; Land Disposal Restric-
tions. Final Rule. Federal Register 51(216):40572-40654. (Appropriate
changes in 40 CFR 260-262, 264, 265, 268, 270, and 271 as of 1987 ed.).
2-26
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EPA. 1986c. Toxicity Characteristic Leaching Procedure (TCLP). Federal
Register 51(216):40643-40653. (Incorporated as 40 CFR 268, Appendix I
as of 1987 ed.)«
EPA.
as of 1987 ed.)«
1986d. Identification and Listing of Hazardous Wastes. 40 CFR 261,
Subparts C and D, and Appendix VIII. U.S. Government Printing Office,
Washington, D.C.
EPA. 1986e. Hazardous Waste Management System; Identification and Listing
of Hazardous Waste; Notification Requirements; Reportable Quantity
Adjustments; Proposed Rule. Federal Register 51(114):21648-21693.
[See also Federal Register 52(95): 18583-18585].
EPA. 1986f. Report to Congress: Minimization of Hazardous Wastes. Execu-
tive Summary and Fact Sheet. October 1986.
EPA. 1987. Land Disposal Restrictions for Certain "California List" Hazard-
ous Wastes and Modifications to the Framework; Final Rule. Federal
Register 52(130):25760-25792.
Haxo, H. E., R. S. Haxo, N. A. Nelson, P. D. Haxo, R. M. White, and S.
Dakessian. 1985. Liner Materials Exposed to Hazardous and Toxic
Wastes. EPA-600/2-84-169 (NTIS No. PB 85-121-333). U.S. Environment
Protection Agency, Cincinnati, OH. 256 pp.
Haxo, H. E., and S. Dakessian. 1987. Assessment of the Potential for In-
compatibility of Soil Liner Materials with Specific Organic Compounds.
In: Proceedings of HAZMACON 87, Hazardous Materials Management Con-
ference and Exhibition, April 21-23, 1987, Santa Clara, CA. Association
of Bay Area Governments, Oakland, CA. pp 496-512.
Haxo, H. E., T. P. Lahey, and M. L. Rosenberg. 1988. Factors in Assessing
the Compatibility of FMLs and Waste Liquids. EPA/600/2-88/017 (NTIS No.
PB 88-173-372/AS). U.S. Environmental Protection Agency, Cincinnati,
OH. 143 pp.
Haxo, H. E. 1988. Transport of Dissolved Organics from Dilute Aqueous
Solutions Through Flexible Membrane Liners. In: Proceedings of the
Fourteenth Annual Solid Waste Research Symposium: Land Disposal, Re-
medial Action, Incineration and Treatment of Hazardous Waste, May 9-11,
1988. U.S. EPA, Cincinnati, OH. 21 pp. (In press).
Hildebrand, J. H., and R. L. Scott. 1950. The Solubility of Nonelectro-
lytes. 3rd ed. Rheinhold Publishing Corp. (Reprinted by Dover
Publications, NY, 1964.) 488 pp.
Lysyj, I., R. Hillger, J. S. Farlow, and R. Field. 1987. A Preliminary
Analysis of Underground Tanks Used for CERCLA Chemical Storage. In:
Land Disposal, Remedial Action, Incineration and Treatment of Hazard-
ous Waste. Proceedings of the 13th Annual Research Symposium. EPA/
600/9-87/015. U.S. Environmental Protection Agency, Cincinnati, OH.
pp 156-159.
2-27
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McArdle, J. L., M. M. Arozarena, and W. E. Gallagher. 1987. A Handbook
on Treatment of Hazardous Waste Leachate. EPA/600/8-87-006 (NTIS
PB 87-152 328/AS). U.S. Environmental Protection Agency, Cincinnati,
OH.
McNabb, G. D., J. R. Payne, P. C. Harkins, W. D. Ellis, and J. A Bramlett.
1987. Composition of Leachate from Actual Hazardous Waste Sites. In:
Land Disposal, Remedial Action, Incineration and Treatment of Hazardous
Waste. Proceedings of the 13th Annual Research Symposium. EPA/600/9-
87/015. U.S. Environmental Protection Agency, Cincinnati, OH. pp
130-138.
National Research Council/National Materials Advisory Board. 1983. Manage-
ment of Hazardous Industrial Wastes: Research and Development Needs.
Publication NMAB-398. National Academy Press. Washington, D.C.
Versar, Inc. and Jacobs Engineering Group. 1986. Waste Minimization Issues
and Options. Volume 1. EPA/530SW 86-041. October, 1986. U.S. Envi-
ronmental Protection Agency, Washington, D.C.
Wiles, G. C. 1986. A Review of Solidification/Stabilization Technology.
International Speciality Conference on Performance and Costs of Altern-
atives for Land Disposal of Hazardous Wastes. Trans. Air Pollution
Control Association, TR-9, New Orleans, LA. Air Pollution Control
Association, P.O. Box 2861, Pittsburgh, PA. pp 60-70.
2-28
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CHAPTER 3
WASTE CONTAINMENT ON LAND AND CONSTITUENT TRANSPORT
WITHIN AND OUT OF A CONTAINMENT UNIT
3.1 INTRODUCTION
This chapter describes basic concepts and factors in the transport
of mobile constituents of a solid or liquid waste contained in a storage or
disposal facility and their escape into the environment. The paths and
mechanisms by which these constituents are transported within a containment
unit are discussed with particular emphasis on transport within multilayered
liner systems, such as those described in the EPA draft Minimum Technology
Guidance documents on double liner and final cover systems for hazardous
waste landfills and surface impoundments (EPA, 1985; EPA, 1987). Such
systems include FMLs, compacted soil liners, and systems for collecting and
removing liquids, e.g. leachate. This chapter concentrates on closed FML-
lined landfills and FML-lined surface impoundments that meet the requirements
of RCRA and the Hazardous and Solid Waste Amendments of 1984.
The function of a liner system in a containment unit is to minimize and
control the migration of polluting constituents in the waste or liquid being
contained and prevent them from entering the environment either through the
air or through the ground. However, even though FMLs are nonporous and
cannot be permeated by liquids per se, gases, vapors and liquids can permeate
an FML on a molecular level. Thus, even if an FML is free of holes, some
constituents of wastes can still permeate through an FML into the liner
system and may escape into the environment. A properly designed and con-
structed liner system should minimize and control the escape of pollutants
over extended periods of time.
In a waste storage or disposal unit, the mobile constituents will
migrate throughout the unit by advection in the liquid which carries dis-
solved constituents and by diffusion as gases, vapors, or dissolved con-
stituents. The movement of the mobile constituents is determined by factors
such as temperature, concentration, vapor pressure, partitioning, gravity,
and density. The mobile constituents will tend to migrate so that there is
equilibrium throughout the mass within the unit and with the surrounding
environment (Haxo et al, 1988; Haxo, 1988). As covers are not placed on
surface impoundments, moisture and the volatile constituents in wastewaters
can escape from surface impoundments into the atmosphere.
3-1
-------
Transport of chemical species can occur through FMLs without pinholes,
punctures, or other breaks, but depends on the solubility and diffusibility
of the permeating species in a particular FML. In contrast to soils, sands,
silts, and clays which are porous, the driving force for permeation through
FMLs is not gravity and the hydraulic head of the liquid but a chemical
potential (for which concentration is a good approximation in most cases) or
partial pressure gradient across the FML. Species migrate through an FML
from a higher to a lower concentration. Because the concentration of most
potentially contaminating or polluting constituents existing in the waste
will be higher than their concentration in the environment, there will be a
tendency for the mobile species to equilibrate within a unit and to move
towards the outer boundaries and out of the unit.
The rate and ultimate magnitude of transport of gases, vapors, and
liquids out of a land storage or disposal unit into the outer environment can
be affected by the specific environmental conditions that exist in the ground
or in the atmosphere. For instance, in the case of surface impoundments,
wind, relative humidity, atmosphere, and temperature can have a significant
effect on the evaporation of water and the escape of volatile constituents of
the impounded liquid (Cohen, 1986). In the case of transport through the
bottom liner system, in both a surface impoundment and a landfill, the rate
would be affected by such factors as the type of soil below the liner system
and the proximity to groundwater and an aquifer. Even though covered land-
fills can be highly "sealed" with FMLs that have low permeability, the effect
of rising and falling barometric pressure forces the waste containment system
to "breathe" and thus release constituents to the environment and bring air
into a landfill.
All components of a liner system can potentially interact with waste
constituents, whether they be gases, vapors, or liquids. These systems are
multilayered composites constructed of different materials, some of which are
polymeric. Each component of these systems is designed to fulfill a specific
function while it is at the same time exposed to compressive, tensile, and
multiaxial stresses. Interaction between waste constituents and the liner
system becomes important in terms of the long-term functioning of the system
because of the combined effects of mechanical stresses and interaction with
the waste constituents. Of particular concern is the effect that waste
constituents can have on components of the leachate drainage and collection
and leak-detection subsystems. The absorption of organic waste and waste
constituents could cause softening of a synthetic drainage medium, such as a
geonet, with the result that the drainage system could collapse under the
overburden and no longer function satisfactorily.
In this chapter, the mechanisms of transport of mobile chemical species
within waste storage and disposal units and the multilayered composites that
make up the liner and cover systems of landfills and surface impoundments are
discussed. Some of the basic properties of both waste liquids and FMLs that
affect the rate and direction of transport of waste constituents are also
discussed.
3-2
-------
3.2 PHYSICAL AND CHEMICAL ATTRIBUTES OF WASTE LIQUIDS,
GASES, AND VAPORS
As is described in Chapter 2, the wastes that are contained in both
MSW and hazardous waste landfills are highly complex, nonhomogeneous mixtures
of solids, liquids, vapors, and gases. Such mixtures can contain a high
volume of airspace and voids, which will be at atmospheric pressure. The
solid materials can be either organic or inorganic or both. The organic
waste is probably degradable; some solids may be water-soluble, and some may
sublime into the air voids. The liquid phase is usually an aqueous solution
containing dissolved organics, inorganics, and gases; there can also be
liquid phases of organics, particularly in surface impoundments. The gaseous
phase can contain "permanent" or noncondensable gases, such as nitrogen,
oxygen, carbon dioxide, methane, and hydrogen sulfide, and vapors of liquids,
such as water and the volatile organics that exist in the liquid state or
dissolved in the liquid phase. The composition of each phase does not remain
constant, but is subject to change with time due to consolidation of the
solid waste, to movement of mobile species, and to chemical and biological
activities within the waste.
Of particular importance, from the standpoint of containment, are the
mobile constituents, such as liquids, vapors, and gases, which are pre-
sent or generated in the landfill, the movement of these constituents is
governed by their chemical and physical properties, the conditions that
exist in the landfill, and the relevant driving forces (Versar, 1984). For
example, dissolved volatile constituents at dilute concentrations in water,
which in this case would be the leachate, will have a vapor pressure cor-
responding proportionally to the mole fraction of the constituent in the
solution. Thus, depending on their volatility and Henry's law constant,
volatile constituents will enter pores. This constant, K£, of a volatile
solute is defined by:
(3-1)
at infinite dilution, where P£ is the vapor pressure above the solution
divided by the mole fraction, /2, of the solute in the solution. Con-
stituents in the leachate, both volatile and nonvolatile, can also be ab-
sorbed by the solids, such as the FMLs, by partitioning from the leachate
phase into the solid phase. Partitioning and its effect on permeability are
discussed in Section 5.4.1.7 and in more detail by Haxo et al, 1988 and Haxo,
1988. Liquid components will tend to gravitate to the bottom of the fill
where they will be collected in the leachate collection and drainage system.
When the liquid or leachate is in contact with the bottom liner, some dis-
solved constituents can then be absorbed in and pass through the FML into
the leachate detection, collection, and removal system below by vapor trans-
mission and by diffusion. The amount that would be absorbed by the liner
system depends on the concentration of the constituents in the leachate
and the relationship of the partitioning and solubility parameters among the
various components of the liner and drainage system.
3-3
-------
Gases, vapors, and dissolved chemical species tend to move through a
mass in accordance with their chemical potential or activity. The movement
of chemical species is from a high potential to a low potential. In the
transport of a chemical species through a membrane between two ideal solu-
tions of chemicals and vapors, chemical potential is directly related to
the concentration or the vapor pressure of the permeating species. In most
situations, however, there is deviation from ideality. Nevertheless, con-
centration is a reasonable approximation of chemical potential. Concentra-
tions of the mobile constituents will tend towards an equilibrium throughout
an impoundment unit and the surrounding environment predominantly by gas and
vapor transmission as driven by chemical potential.
3.3 CHARACTERISTICS OF BARRIER MATERIALS
3.3.1 Introduction
The materials that are used in lining waste containment units consist of
both porous and nonporous materials. The porous materials include clay soils
which are used both in the composite bottom liner and in the cover system of
a closed landfill. In addition to the clay soils, a variety of other porous
materials are also used, including sand, gravel, and various geotextiles for
drainage and venting. The nonporous materials are principally the FMLs and
the various sprayed-on asphaltic-type materials.
Both porous and nonporous materials are permeable to various gases,
vapors, and liquids; however, the mechanisms for permeation are substan-
tially different. Basically, liquids, vapors, and gases permeate the porous
materials through interconnecting pores or capillaries within the maerial;
gases and vapors permeate nonporous materials on a molecular basis, which
requires that the permeating molecules move individually among the polymer
chains which are continually in molecular motion.
In this section, transport through the two basic types of materials that
are used as liners, porous and nonporous, is discussed and the terminology
that is used in this TRD with respect to permeation is set forth. The term
"permeability" is used to describe transport through both types of materials,
even though the two types have widely different structures. In general,
therefore, the term "permeability" does not imply anything about the mecha-
nism of permeation; several permeation or transport mechanisms may be operat-
ing concurrently, depending on the barrier.
3.3.2 Permeation Through Porous Materials
With the exception of some metals and plastics, most materials that are
encountered are porous in nature. They include such building materials as
soils, bricks, concrete, limestone, and wood. They also can include various
filtration media that are used in the purification of water, etc. For a
material to be termed porous, it must be one of the following two types:
- The material contains spaces, voids, or pores that are embedded in a
solid or a semi sol id matrix, i.e. pores that are not interconnected.
3-4
-------
These pores can contain fluids, air, waste, or a mixture of different
fluids.
- The material contains pores that are connected
a fluid introduced on one side of the material
to pore and emerge on the other side.
in such a way that
will flow from pore
Examples of porous materials that do not contain interconnected pores in-
clude closed cell foams used for flotation and blown or expanded polystyrene
insulation. The vast majority of porous materials, including the soils and
are used in the construction of waste
the second type. These materials contain
networks of capillary channels of non-
different surface characteristics. Flow
place within extremely complicated micro-
the other porous materials that
containment units, however, are of
interconnecting three-dimensional
uniform sizes and shapes and of
through these materials can take
scopic boundaries. This pore structure is inseparable from the convective,
diffusive, and interfacial effects that take place within the pores.
Lambe and Whitman (1969) discuss flow phenomena in soils of a single
component liquid, such as water. Figure 3-1 illustrates schematically
the path of one-dimensional flow of a liquid on the macroscopic scale as well
as the microscopic scale. The flow path on a microscopic scale is the
highly tortuous path that liquid must follow in passing from pore to pore
through a soil to get from point P to point Q. On a macroscopic scale, a
soil can also be treated as continuum without regard to pores or pore shapes
so that a liquid can be considered to flow from point P to point Q along a
straight line at an effective velocity. Most of the technical information
that has been developed on the permeability of soils, particularly by
engineers, uses the model of macroscopic flow to describe the flow of a
liquid through soil.
Flow path-macroscopic scale
Flow path-microscopic scale
Figure 3-1. Flow pattern of liquid through a soil on macroscopic and
microscopic scale.
3-5
-------
Macroscopic flow through saturated porous media follows Darcy's law
which was determined experimentally by measuring the flow of water through a
saturated column of sand. Darcy's experiment is presented schematically in
Figure 3-2. The flow rate was found to be proportional to the difference in
hydraulic head divided by the length of the column, as is shown in the
following equation (Lambe and Whitman, 1969):
hi - h?
Q = k — £• A = kiA , (3-2)
where
Q = the rate of flow,
k = a constant (Darcy's coefficient of permeability),
hi = the height above a reference level to which the water rose in a
standpipe inserted at the the entrance end of the filter bed,
\\2 = the height above a reference level to which the water rose in a
standpipe inserted at the exit end of the filter bed,
L = the length of sample,
A = the total inside cross-sectional area of the sample container, and
hi -
=
, the hydraulic gradient.
Figure 3-2. Darcy's experiment. (Based on Lambe and Whitman, 1969,
p 252).
3-6
-------
With most liquids in saturated soils, the flow follows Darcy's law;
however, in the case of waste liquids and contaminanted water, the flow can
deviate from the law due to interactions between the waste liquid and the
surface of the soil particles. These interactions become important in the
effect of escape of dissolved species through the FML component of a compo-
site liner on the underlying soil component, and also can be of concern in
the dikes that form the support for the liner system in waste facilities.
Dullien (1979), in his treatise on porous media, discusses permeation
through porous media in terms of interaction among three main factors,
i.e. transport phenomena, interfacial effects, and pore structure. He
presents highly pertinent information on the role of pore structure and
uses this information to interpret experimental results that have been
reported in the literature.
Dissolved chemical species, either organic or inorganic, not only can
permeate a soil advectively (i.e. the liquid acts as the carrier of the
chemical species), but also by diffusion in accordance with Pick's two laws
of diffussion; thus, in some cases, the chemical species can precede the flow
of the liquid carrier.
Daniel et al (1988) discuss the transport of inorganic components by
diffusion through compacted clay soils and present data showing that the
effective diffusion coefficient for anions diffusing through compacted clay
soils is about 2 x 10~9 m2/s and that breakthrough of dissolved species
can occur much sooner than predicted by models developed from the hydraulic
conductivity of the soil, the hydraulic gradient, and the effective porosity
of the soil. Daniel et al (1988) also show that cations tend to diffuse more
slowly due to ion-exchange and other reactions, and that the compaction and
water content have little influence on the diffusion coefficient. On the
other hand, they observed that subtle variations in geochemical factors can
cause significant changes in the rate of diffusion transport.
3.3.3 Permeation Through Nonporous Materials
In contrast to the porous soils and various admixes that have been
used as principal barriers to prevent the migration of mobile constituents
from waste containment units, FMLs are nonporous membranes. It should be
pointed out that FMLs are special types of synthetic membranes. All syn-
thetic membranes are not necessarily nonporous; many are in reality porous,
as they are manufactured with very small holes and are used as filters, as
desalinization membranes, and as membranes for chemical and biological
purification, dialysis, and reverse osmosis (Kesting, 1985). Membranes
that are used as FMLs are nonporous and are generally considered to be
homogeneous materials, though in some classifications they may be considered
nonhomogeneous due to additives, fillers, the crystalline content of semi-
crystalline FML compounds, and fabric reinforcement in manufactured sheet-
ing. Even though polymeric FMLs are manufactured as solid nonporous mate-
rials, they contain interstitial spaces between the polymeric molecules
through which small molecules or other chemical species can diffuse. Thus,
3-7
-------
all polymeric FMLs are permeable to a degree. The permeant, in this case,
migrates through the material on a molecular basis by an activated diffusion
process and not as a liquid which can flow through the pores of a soil and
carry dissolved chemical species, as is described in the previous subsection.
This transport process of chemical species through an FML involves three
steps:
~ The solution or absorption of the permeant at the surface of the FML.
- Diffusion of the dissolved species through the FML.
- Evaporation or desorption of the permeant at the downstream surface of
the FML.
The driving force for this type of activated permeation process is the
"activity" or chemical potential of the permeant which is analogous to
mechanical potential and electrical potential. The chemical potential of
the permeant decreases continuously in the direction of the permeation, as
is shown in Figure 3-3, which schematically presents variations of permeant
chemical potential and concentration with distance through a membrane in
permeation in the steady state.
In the transmission of a permeant through a membrane, Step 1 depends
upon the solubility of the permeating species in the membrane and the rel-
ative chemical potential of the permeant on both sides of the interface.
In Step 2, the diffusion through the membrane involves a variety of
factors including size and shape of the molecules of the permeating species,
and the molecular characteristics and structure of the polymeric membrane
(Crank and Park, 1968). For example, the presence of fillers, crystalline
domains, and crosslinks tend to reduce diffusion rates by interfering with
molecular movement of the polymer chains. The presence of plasticizers or
the swelling of the membrane by solvents tends to increase the rates of
diffusion by opening up the molecular structure of the polymer. Higher
temperatures result in higher rates of diffusion due to increased molecular
motion of both the permeating species and the polymer in the FML.
A steady state of the flow of the constituents will be established
when, at every point within the FML, flow can be defined by Fick's first law
of diffusion:
Qi = - Di^l , (3-3)
where
Qi = the mass flow of constituent "i" in g cm'2 sec"1,
D-j = local diffusivity in cm2 sec'1,
3-8
-------
Ci = the local concentration of constituent "i" in g cm'3, and
x = the thickness of the FML in cm.
It should be noted that the concentration of constituent "i" referred to in
Pick's law is within the mass of the FML. For gases, the mass units can be
expressed as volume units, e.g. cm3 at standard temperature and pressure.
ro
CD
O
Solution 1
Solution 2
1
-------
Step 3 is similar to the first step and depends on the relative chemical
potential of the permeant on both sides of the interface at the downstream
membrane surface.
Chemical potential is an idealized concept which indicates the direction
in which the migration or permeation will go. It will always go from high to
low potential. To use concentration directly to replace chemical potential
requires the individual molecules of the permeating species to neither
interact with each other nor interact with the membrane they are permeating.
This condition approximately exists when a permanent or noncondensable gas,
such as oxygen, nitrogen, and helium, permeates a membrane. However, the in-
dividual molecules of organic species can interact with each other and with
the polymer to increase solubility of the species in the FML, and as a result
partition to the FML. This subject is discussed further in Chapter 5 with
respect to permeation of organics in dilute aqueous solutions through FMLs
(Section 5.4.1.7). If concentration and chemical potential are equal, then
the concentration of the constituent can be used directly to determine the
rate of permeation. The relationship between the concentration in phases
that contact each other and the chemical potential is determined by the
solubility parameters of the species and partitioning of the permeating
constituent between the fluid containing the permeant and the membrane, as
well as partitioning of the permeant between the membrane and the fluid on
the opposite side.
Concurrent with the absorption of volatile organic species by an FML and
their transmission through the FML, the FML can retain a portion of the
organics and swell and, in turn, become somewhat more permeable. Though
other compositional factors contribute, the extent to which an FML will
absorb a vapor or liquid depends largely on the near matching of the respec-
tive solubility parameters of the organic and the FML, as is discussed in
Chapter 4 (Section 4.2.2.4.3). Mass flow, Qj, of constituent "i" can also
be defined by the following equation:
Qi = -°iSi^ , (3-4)
where
Q-j = the mass flow of constituent "i" in g cm~2 sec~l,
D-j = local diffusivity in cm2 sec"*,
S-j = Henry's law constant of component "i" in sec2 cm"2,
p = the vapor pressure of constituent "i" in g cm"1 sec'2, and
x = the thickness of the FML in cm.
3-10
-------
When the solubility parameters of the membrane and the permeating constituent
are similar, it is likely that Henry's law constant also termed solubility
coefficient, S, and the diffusion coefficient, D, will be dependent on the
concentration of the permeating constituent throughout the FML as will the
permeability coefficient, P. An "integrated" permeability coefficient, P,
is often used as a convenient method of describing permeation between two
vapor pressures, as is shown in the equation:
- '
P =
P2 - P! '
where
PI = the vapor pressure of constituent "i" on Side 1 of the membrane,
and
P2 = the vapor pressure of constituent "i" on Side 2 of the membrane.
Film thickness may also change with the concentration due to swelling, but
the usual practice is to use the unswollen film thickness and incorporate all
corrections into the integrated permeability coefficient.
In steady-state permeation, permeants that cause swelling result in a
nonlinear concentration profile through the FML. Most of the resistance to
transport is localized on the outflow side of the FML. This situation is
analogous to permeation of composite membranes. In addition, if the swelling
results in the relaxation of stresses produced during membrane manufacture,
the permeability will change with the degree of swelling.
3.4 TRANSPORT PROCESSES AND DRIVING FORCES INVOLVED
IN THE MIGRATION OF CHEMICAL SPECIES
In a landfill, the mobile constituents (i.e. the liquids, gases, and
vapors) will move through the airspaces in the waste mass. The liquids which
contain dissolved constituents can move downwards by gravity and upwards
through channels by capillary wetting of solid particles. The gases and
vapors will move by diffusion through the available airspaces. Due to the
solubility of gases and vapors in liquids and the volatility of the liquids,
there are exchanges between the constituents, depending on such driving
forces as concentration, vapor pressure, and temperature. These latter
driving forces are all related to the chemical potential of individual
species. Though the temperature within a landfill tends to be reasonably
consistent, there are variations from the top to the bottom during the course
of a year, perhaps even a day. The flow of vapors and waste constituents
will be towards the lower temperature; thus, there will be a driving force
towards the bottom of a landfill for all liquids. Vapors (e.g. water vapor)
tend to condense on colder surfaces. Since relative humidity within a waste
will probably be 100%, moisture condensation may occur in the leachate
drainage and detection systems.
3-11
-------
Depending on the solid waste and the surface tension of the waste
liquids, there can be considerable movement in all directions via the wetting
of the solid particles. This wicking action is a possible means of raising
components from lower parts of a landfill to the top, where they can escape
to the atmosphere or, in the case of dissolved salts, form high concentra-
tions of salts on the top of the landfill cover (Lutton, 1982; Bell and
Parry, 1984).
In the case of surface impoundments in which an aqueous phase predomi-
nates, constituents of the waste that exceed their solubility in the aqueous
phase may either rise to the top, as in the case of oils and low-specific
gravity materials, or collect on the bottom, as in the case of many halo-
genated solvents. Those that rise to the surface may interact with the
liner and cause swelling and damage; those that collect on the bottom may
contact the FML and similarly swell and damage the FML.
3.5 TRANSPORT OF WASTE CONSTITUENTS WITHIN A CLOSED LANDFILL
From the standpoint of the effects that a leachate may have on the
liner system of a closed landfill, it is necessary to know the path that the
different mobile waste constituents travel as they move through the landfill.
They can be absorbed by the various components of the liner system, the
leachate collection system, or the cover system, causing changes in the
properties of these components that may affect their ability to function as
designed.
Of particular importance is the possible increase that absorbed organics
would have on the permeability of the FML barrier. An increase would allow
organic chemical species to enter the leachate detection, collection, and
removal system more readily. Those organics that permeate through the FML
may then be absorbed from the vapor phase by drainage nets and other poly-
meric components of the system, causing these components to soften. As they
would be under load, they may lose their transmissivity and their designed
drainage quality. (The design of double liner systems is discussed in
Chapter 7).
In addition to the potential downward movement of these species toward
the liner system, volatile organics can move upwards toward the cover by
diffusion as can liquids, to some extent, by capillary action. Volatile
constituents may permeate through the FML in the cover system into the soil
where they could possibly adversely affect plant growth. They would then
migrate into the atmosphere. The use of an FML in covers should aid in the
control of escaping gases and vapors by improving collection efficiency and
reducing permeation losses as well as decreasing intrusion of waste into the
landfill.
3.6 ESCAPE OF CONSTITUENTS FROM WASTE STORAGE AND
DISPOSAL FACILITIES
Because polymeric materials are not totally impermeable (Haxo et al,
1988; Haxo, 1988), the performance goal of a liner system for a waste
3-12
-------
containment unit is to allow, for extended periods of time, no more than a
minimum escape of potentially polluting chemical species into the environ-
ment. This level of escape should be below the level that would have any
adverse effects on human health and the environment.
In spite of the measures taken to prevent the escape of constituents
from a waste into the environment, small amounts can escape by diffusion
even from a closed, double-lined landfill. The magnitude of what does escape
can be affected to a certain extent by various hydrogeological and environ-
mental factors; for example, escape through the bottom liner can be affected
by the type of soil below the containment boundary and the proximity to
groundwater. The escape of volatile organics to the atmosphere from a closed
landfill can be affected by weather conditions; for example, the wind,
temperature, relative humidity, and rain. The rate of escape can be con-
trolled by venting systems in landfill covers which are designed to prevent
the accumulation of gases, particularly of methane in MSW landfills, and to
control their escape. Changes in barometric pressure can result not only
in the movement of air into a landfill, but also in the movement of gas and
vapor components out of a landfill. Variations in barometric pressure have
been found to affect the leachate levels in sump systems; decreased baro-
metric pressure has resulted in higher levels of leachate in a collection
sump (i.e. in a higher hydraulic head on the lining system), as is shown in
Figure 3-4 (Kirkham et al, 1986).
3.6
395
Figure 3-4. Comparison of leachate levels in a leachate collection
sump to atmospheric pressure. (Source: Kirkham et al,
1986).
3-13
-------
In the case of surface impoundments, where the surface is exposed to the
atmosphere, volatile constituents can leave the impoundment and move into the
atmosphere, as is discussed by Thibodeaux et al (1984). This aspect has been
of concern due to potential air pollution. Various efforts have been made to
use FMLs as covers, such as those described by Kays (1986). Covers have been
used on reservoirs in the past to reduce evaporation of water. However, many
surface impoundments are used as evaporation ponds to reduce water content
prior to disposal or further treatment. Wastes containing liquids and solids
of high density and low solubility in water have been covered with water to
prevent escape of waste constituents into the atmosphere (Farmer et al,
1980). The transport of organic pollutants into the environment and multi-
media modeling techniques predicting their fate in the environment are
discussed by Cohen (1986).
3.7 REFERENCES
Bell, R. M., and G. D. R. Parry. 1984. Upward Migration of Contaminants
Through Covering Systems. In: Proceedings of the 5th National Con-
ference on Management of Uncontrolled Hazardous Waste Sites, November
7-9, 1984. Washington, D.C. Hazardous Materials Control Research
Institute, Silver Spring, MD. pp 588-91.
Cohen, Y. 1986. Organic
20(6):538-544.
Pollutant Transport. Environ. Sci. Technol
Crank, J.,
Press,
and 6. S. Park, eds.
Inc. (London) Ltd. NY.
1968. Diffusion
426 pp.
in Polymers. Academic
Daniel, D. E., C. D. Shackelford, and W. P. Liao. 1988. Transport of
Inorganic Compounds Through Compacted Clay Soil. In: Proceedings of
the Fourteenth Annual Solid Waste Research Symposium: Land Disposal,
Remedial Action, Incineration and Treatment of Hazardous Waste, May
9-11, 1988. U.S. Environmental Protection Agency, Cincinnati, OH.
In press.
Dullien, F. A. L. 1979.
Academic Press, NY.
Porous Media
396 pp.
- Fluid Transport and Pore Structure.
EPA. 1985. Minimum Technology Guidance on Double Liner Systems for Land-
fills and Surface Impoundments—Design, Construction, and Operation.
Draft. EPA 530-SW-85-014, May 24, 1985. U.S. Environmental Protection
Agency. Washington, D.C.
EPA. 1987. Minimum Technology Guidance on Final Covers for Landfills
and Surface Impoundments. Draft. EPA Contract No. 68-3243, Work
Assignment No. 2-14. U.S. Environmental Protection Agency, Washington,
D.C. 31 pp.
Farmer, W. J., M.-.S Yang, J. Letey, and W. F. Spencer. 1980.
of Hexachlorobenzene Wastes. EPA 600/2-80-119. U.S.
Protection Agency, Cincinnati, OH. 79 pp.
Land Disposal
Envi ronmental
3-14
-------
Haxo, H. E., T. P. Lahey, and M. L. Rosenberg. 1988. Factors in Assessing
the Compatibility of FMLs and Waste Liquids. EPA 600/52-88/017 (NTIS
PB-88-173-372/AS). U.S. Environmental Protection Agency, Cincinnati,
OH. 143 pp.
Haxo, H. E. 1988. Transport of Dissolved Organics from Dilute Aqueous
Solutions Through Flexible Membrane Liners. In: Proceedings of the
Fourteenth Annual Solid Waste Research Symposium: Land Disposal,
Remedial Action, Incineration and Treatment of Hazardous Waste, May
9-11, 1988. U.S. EPA, Cincinnati, OH. 21 pp. (In press).
Kays, W. B. 1986. Construction of Linings for Reserviors, Tanks, and
Pollution Control Facilities. 2nd ed. John Wiley and Sons, NY.
454 pp.
Kesting, R. E. 1985. Synthetic Polymeric Membranes - A Structural Perspec-
tive. 2nd Edition. McGraw-Hill, NY. 350 pp.
Kirkham, R. R., S. S. Tyler, and G. W. Gee. 1986. Estimating Leachate
Production from Closed Hazardous Waste Landfills. Interagency Agreement
No. DW89007401. U.S. Environmental Protection Agency, Cincinnati, OH.
80 pp.
Lambe, T. W., and R. V. Whitman. 1969. Soil Mechanics. SI Version. John
Wiley and Sons, NY. 553 pp.
Lutton, R. J. 1982. Evaluation of Cover Systems for Solid and Hazardous
Wastes. NTIS PB 81-166340. Cited in: Bell, R. M., and G. D. R. Parry.
1984. Upward Migration of Contaminants Through Covering Systems. In:
Proceedings of the 5th National Conference on Management of Uncontrolled
Hazardous Waste Sites, November 7-9, 1984. Washington, D.C. Hazardous
Materials Control Research Institute, Silver Spring, MD. pp 588-91.
Lutton, R. J. 1986. Design, Construction, and Maintenance of Cover Systems
for Hazardous Waste--An Engineering Guidance Document. U.S. Environ-
mental Protection Agency, Cincinnati, OH. 183 pp.
Thibodeaux, L. J., C. Springer, and G. Hill. 1984. Air Emissions of Vol-
atile Organic Chemicals from Landfills: A Pilot-Scale Study. In: Land
Disposal of Hazardous Waste. Proceedings of the 10th Annual EPA Re-
search Symposium. EPA 600/9-84-007. U.S. Environmental Protection
Agency, Cincinnati, OH. pp 172-180.
Versar, Inc. 1984. Physical-Chemical Properties and Categorization of RCRA
Wastes According to Volatility. Draft Report. EPA Contract 68--03-3041,
Work Assignment No. 4, Subtask No. 2. U.S. Environmental Protection
Agency, Cincinnati, OH.
Yasuda, H., H. G. Clark, and V. Stannett. 1968. Permeability. In:
Encyclopedia of Polymer Science and Technology. Vol. 9. Interscience,
NY. pp 794-807.
3-15
-------
CHAPTER 4
FMLS AND OTHER CONSTRUCTION MATERIALS
4.1 INTRODUCTION
This chapter discusses various types of materials used in the con-
struction of lined containment facilities, particularly those for the
storage or disposal of wastes. These materials, which are used to fulfill
a variety of functions in the structure of such facilities, are listed in
Table 4-1 by their function. Depending on the service that may be required,
these materials may need to perform from a relatively few years, as in the
case of some storage units, up to 100 years or more, as in the case of some
landfills, and to function in such a manner that hazardous materials are
under control and do not migrate from the unit in an uncontrolled manner.
TABLE 4-1. MATERIALS USED IN THE CONSTRUCTION OF LINER AND LEACHATE CONTROL
SYSTEMS FOR WASTE STORAGE AND DISPOSAL FACILITIES AND THEIR FUNCTIONS^
Material
FMLs
Geotextiles
Geogrids
Geonets
Composites
Sand/gravel
Concrete
Pipe
Soil
Barrier
P
n/a
n/a
n/a
P or S
...
P or S
Sepa-
ration
S
P
S
S
P or S
S
...
...
Soil
rein-
Support forcement
n/a
P
P
n/a
P or S
...
P
...
P
Filtr-
ation
n/a
P
n/a
n/a
P or S
S
• • *
...
...
Leachate
drainage
and
collection13
n/a
P
n/a
P
P or S
P
S
P
...
aP = primary function; S = secondary function; n/a = not applicable.
bAlso part of the leak-detection system.
4-1
-------
Emphasis is placed on polymeric materials consisting of the FMLs, geo-
textiles, geogrids, geonets, geocomposites, and pipe. Discussion of soils
for liners or soils for membrane/soil liner composites is referenced largely
to the TRD on soil prepared by Research Triangle Institute (Goldman et al,
1985). Sands and gravels and concrete are discussed in Chapter 7 on design
and construction. Also discussed in this chapter are the admix liners and
sprayed-on FMLs.
Preliminary to the discussion of polymeric components that are used in
the construction of liner and leachate control systems, the basic charac-
teristics of polymers that are common to polymeric products are discussed
with particular reference to those properties that are of importance in the
performance of the component in service. These include such characteristics
as composition, the effect of temperature on properties, the creep and
relationship of polymers under mechanical stress, the effect of multiaxial
straining, permeability to gases, water, and organic liquids, the sensitivity
to organic liquids, stress cracking and fatigue under stress, long-term
durability of polymers in waste containment environments, and the importance
of considering the combination of properties in the evaluation of polymeric
materials. The components of liner systems are discussed individually.
The following subjects are discussed with respect to FMLs:
- The polymers used in currently available FMLs.
- The manufacturing processes.
- The fabrication and seaming of FMLs into liners.
- The properties of importance to liner performance in service, such
as permeability, mechanical properties, chemical resistance, and
durability.
- Testing and evaluation of FMLs in the laboratory with respect to
analytical properties, physical and mechanical properties, permeabil-
ity, environmental effects, performance testing, and fingerprinting.
The geotextiles, geogrids, geonets, geocomposites, and pipe are also discus-
sed individually with regard to their respective compositions, manufacture,
testing, and long-term durability.
Admix liner materials and sprayed on FMLs are described with respect to
types, compositions, properties, and installation.
Information and data are included in this chapter, as well as the
succeeding chapters, on a wide range of materials which have been used for
the lining of containment and conveyance facilities, but are not currently
used in the lining of containment facilities for hazardous wastes. The
information on these materials should be useful for general consideration in
many containment applications. A broad range of information on properties is
included which may be useful in the selection and design of new materials and
components.
4-2
-------
4.2 POLYMERIC MATERIALS
Several of the products used in the construction of liner systems for
waste storage containment units are based on polymeric materials. The use of
polymeric products in civil-engineering applications has increased impres-
sively over the past decade, particularly in the design and construction of
waste management facilities. These products include various rubber and
plastic membranes that have very low permeability to gases, vapors, and
liquids, woven and nonwoven textiles that have various degrees of permea-
bility, various special open constructions designed for high permeability and
liquid flow, and plastic pipes.
Of particular importance is the wide range of functions that polymeric
products perform in liner systems for hazardous waste containment units.
These products are based on a wide range of polymers including rubbers
(elastomers), plastics, fibers, and resins. With this great diversity in
materials and products, an array of tests must be performed on the materials
and the products to assess their quality and ability to perform in a specific
application. For hazardous waste containment applications thorough testing
and evaluation of candidate materials are necessary, even when a material of
a given generic polymer type may be the material of choice. This reflects
the differences that exist in the grades of polymers and additives used in
FMLs, in other geosynthetics, and in plastic pipe.
Each construction material in a liner system requires testing and
evaluation in terms of the specific facility and- environmental condition in
which it is designed to perform. Thus, if a material will probably be
exposed to a waste liquid or its vapors, it must be compatible with that
particular waste stream and be able to maintain its properties over extended
periods of time. Similarly, if the material is to be subjected to loads and
to elevated temperatures, it must be able to function as required without
failure.
The following polymeric materials of construction are being used or
being suggested for use in liner systems (EPA, 1985):
FMLs—To provide a barrier between hazardous substances and mobile
polluting substances and the groundwater; in the closing of landfills,
to provide a low-permeability cover barrier to prevent intrusion of rain
water.
Geotextiles--To provide separation between solid wastes and the drainage
and leachate collection system or between the membrane and cover or
embankment soils; to reinforce the membrane against puncture from the
subgrade or the waste that is placed above it; to provide drainage,
such as in leachate collection and leak-detection systems; to provide
filtration around drainage pipes.
Geogrids—To provide reinforcement of soils on side slopes and embank-
ments.
4-3
-------
Geonets--To provide drainage above and between liners.
Plastic Pipes—To provide drainage in leachate collection and removal
systems and in leak-detection systems. Pipe is also used in the con-
struction of monitoring ports, manholes, and system cleanouts.
This section reviews some of the basic characteristics of the polymeric
materials and products that are used in the construction of systems and in-
dicates the effects of these characteristics on field performance.
4.2.1 Basic Characteristics of Polymeric Materials
All of the materials discussed in this section are based on polymers,
which are products of the chemical, plastics, rubber, and fiber industries.
From the viewpoint of composition, an almost infinite range of polymeric
materials can be produced, though only a small fraction is used in the
manufacture of geosynthetics and pipe. The polymeric materials used in the
manufacture of the FMLs and the ancillary construction materials are listed
in Table 4-2. Polymers within a given type can vary in grade and by the
process by which they were produced. In addition, differences between
materials based on the same polymers are introduced by the product manu-
facturers through compounding with various ingredients designed to enhance or
develop specific characteristics. Knowledge about the composition of a
material used in the construction of a waste management facility can be
important when dealing with hazardous substances and waste liquids containing
organics.
Four general types of polymeric materials are used in the manufacture of
these materials:
- Thermoplastics and resins, such as PVC and EVA.
- Cross!inked elastomers, such as neoprene and EPDM.
- Semicrystalline plastics, such as polyethylenes.
- Highly crystalline, oriented polymers, such as polypropylene and
polyester fibers.
In designing containment facilities and designing the tests needed to assess
important design properties, recognition must be given to basic character-
istics of polymeric compositions. As polymeric materials differ in some
properties from many of the traditional materials used in construction,
some of the important features and characteristics of the polymers used in
products for the construction of liner systems are briefly discussed.
General discussions of some of the basic characteristics of polymers can be
found in Moore and Kline (1984), Rosen (1982), and the Modern Plastics
Encyclopedia (1980-81).
4-4
-------
TABLE 4-2. POLYMERS USED IN THE MANUFACTURE OF MAJOR PRODUCTS FOR
THE CONSTRUCTION OF WASTE MANAGEMENT FACILITIES
Polymer
Butyl rubber (IIR)
Chlorinated polyethylene
(CPE)
Chlorosulfonated poly-
ethylene (CSPE)
Ethyl ene propylene rubber
(EPDM)
Ethyl ene vinyl acetate
(EVA)
Neoprene [chloroprene
rubber (CR)]
Polyamide [nylon (PA)]
Polybutylene (PB)
Polyester terphthalate
(PET)
Polyester elastomer
(PEL)
Polyethylene (PE):
Linear low-density
(LLDPE)
High -density
(HOPE)
Polypropylene (PP)
Polyurethane (PU)
Poly vinyl chloride (PVC):
Plasticized
Unplasticized
Product
Geogrids
Geo- and Plastic
Type FMLs textiles geonets pipe
Rubber X ... ... ...
Rubber X
Rubber X
Rubber X
Resin X
Rubber X
Fiber/ res in Xa X
Resin X ... ... X
Fiber/ res in Xa X X
Resin/rubber X
Resin X ... ... ...
Resin X X X X
Resin X X X
Resin/rubber X ... ... ...
Resin X
Resin ... ... ... X
aUsed as reinforcing fabric in FMLs.
4-5
-------
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Oriented
Semi crystal line semi crystal line
Figure 4-2. Schematics of polymer structures.
These molecular structures are thermoplastic, i.e. at elevated temper-
atures the crystals can melt and become amorphous. Also, increasing temper-
ature will cause softening of the three structures. The secondary forces,
that is the forces between the large molecules, determine the temperature
range at which the molecules form resins or rubbers. When the forces are
smaller, the molecules act independently to yield an elastic rubber material;
when the forces are greater, the material becomes hard and resinous at room
temperature, although at higher temperatures it will soften and become
elastic (Rosen, 1982).
Amorphous polymers, such as rubbers, can be changed chemically and
physically by tying the individual polymer molecules together with primary
bonds to form, in essence, one large molecule. This process of bonding
polymer molecules together is cross!inking or vulcanization; in vulcanization,
sulfur crosslinks are formed between the individual larger polymer molecules
of rubber. A cross!inked mass becomes insoluble in solvents and less sus-
ceptible to changes in properties with changes in temperature.
4.2.1.2 Polymers Vary in Modulus and in Elongation at Break--
Polymeric materials range from soft foam-like materials to high modulus
structural materials. Polymeric materials that are used in waste management
facilities are intermediate in modulus or stiffness. However, their uniaxial
elongation at break ranges from 15% to as much as 1000%. Both properties are
important considerations in designing storage and disposal facilities for
wastes and hazardous substances, particularly for the liner system.
4-7
-------
4.2.1.3 Polymers are Viscoelastic and Sensitive to
Temperature and Rate of Deformation--
All polymeric compositions are viscoelastic; that is, when undergoing a
deformation they show, in varying degrees, both viscous and elastic behavior.
The elastic component behaves like a metal spring and is independent of rate
of deformation and essentially independent of temperature. The viscous
component behaves like a dashpot used in damping a shock and is highly
dependent upon the rate of deformation and upon temperature. Three different
sample models showing different combinations of springs and dashpots for
viscoelastic materials are shown in Figure 4-3. Rubbers, such as natural
rubber and some polyurethanes, tend to have highly elastic components,
whereas many of the plastics have highly viscous components. In performing
tests in extension or compression and in service, the temperature and rate of
deformation that the polymeric material encounters becomes important.
Dashpot-1
Spring-1
Spring
Dashpot
Spring a Dashpot
.Spring
2
Dashpot
2
Maxwell Model
Voigt-Kelvin
Model
Combination
Figure 4-3. Models of viscoelastic materials showing different arrangements
of springs (elastic component) and dashpots (viscous component).
Most of the polymers used in the manufacture of the products discussed
in this section can vary greatly in properties with temperature, even within
the temperature range [-40° to 80°C (176°F)] in which waste containment
facilities may operate. At low temperatures some polymers become glassy and
brittle and at elevated temperatures the thermoplastic polymers become soft
and plastic. These characteristics greatly affect the applications in which
a given polymer can be used. The effect of temperature on polymer properties
is discussed more fully later in this chapter.
4-8
-------
Due to the viscous component of polymeric compositions, the speed at
which they are deformed greatly affects the magnitude of the values that are
obtained, e.g. tensile or tear values. Modulus or stiffness values generally
increase considerably with speed of deformation. The effect on tensile
strength and elongation at break values varies with the polymer. In the case
of semicrystalline materials, such as the PEs, high-speed testing will not
allow time for crystals to align themselves during the test, thus resulting
in lower tensile at break values than those obtained at lower speeds. In
service environments deformation rates can range from rapid impacts to long-
term creep.
4.2.1.4 Amorphous and Crystalline Phases in Semicrystalline
Polymers--
Semi crystal line polymers, such as polyethylene and polyester elastomers,
contain two basic phases:
- An amorphous phase in which the molecular structure is random,
such as in a rubber.
- A crystalline phase in which the molecular structure is highly
ordered.
The crystalline phase imparts stiffness to the polymer and resists the
absorption of organic species; the amorphous phase is softer and can absorb
and transmit organics. Deformation of a semicrystalline polymer results over
time in molecular rearrangement in the crystalline phase. Excessive defor-
mation results in yielding or drawing of the polymer and orientation of the
crystalline phase in the direction of deformation with increases in tensile
strength in that direction such as occurs in drawing fibers to produce high
tensile strength. At the same time the tensile strength in the direction
perpendicular to the deformation can drop substantially.
4.2.1.5 Polymers Tend to Creep and to Relax in Stress--
Compared with more traditional materials of construction, such as steel,
concrete, and wood, polymeric materials have a relatively high tendency to
creep, that is, to increase in length or change dimensions under constant
load or to relax in stress when placed in constant strain. Creep is il-
lustrated schematically in Figure 4-4 for a four-parameter model in exten-
sion. During creep the molecules slip to new positions from which they do
not recover, which results in a permanent set. This characteristic of creep
is important to long-term exposure such as would be encountered by all
components in a liner system. For example, an FML placed on an uneven
surface will tend to deform and be strained in accommodating the irregular-
ities of the surface. In-place drainage nets and pipes are under constant
load and an FML placed over a protrusion is under constant stress.
Relaxation of stress under constant strain can also occur in liner
systems to relieve stress that may have been introduced in a component during
construction. The relaxation of stress can cause loss of seal in a gasket.
4-9
-------
The absorption of organics can soften the polymer and aggravate these
tendencies.
t
•g «)
* CO
Q. >-
t
10
^
CO
to' t,
Time
COMBINED
EFFECTS
Elastic Strain
j^ Inst. Elast. Recovery
Elastic Recovery
Behavior of
components
.,.__..???. of the model
* Inst. Elast. Strain ] '>^
- Permanent Set
t,
Time
Figure 4-4. Strain response or creep of the combination four-parameter
model (Figure 4-3) of a viscoelastic polymeric compound to an
applied stress and its removal is shown as a function of time
by the solid curve. The contributions of the individual four
components of the model to the overall strain are shown in-
dividually by the dotted curves.
4.2.1.6 High Coefficient of Linear Thermal Expansion—
Polymeric materials have thermal coefficients approximately 5-10 times
greater than those of metals and concrete, as is shown in Table 4-3. Having
thermal coefficients in this range can be important in the performance of
materials that are exposed to temperature changes. For the more rubber-like
FMLs, changes in dimension with temperature are not a major problem; however,
for stiffer FMLs, such as the polyethylenes, changes in temperature can cause
considerable deformation, buckling, and flexing of a liner when exposed to
normal weather and high stress in a liner placed without sufficient slack in
hot weather when exposed to cold weather.
4.2.1.7 Importance of Thermal and Strain History—
Polymeric materials tend to have "memory," that is, the deformation
during processing and forming into sheets leaves "frozen" residual strain in
4-10
-------
many polymers. This results in a "grain" effect which can lead to different
property values in different directions of test; consequently, tensile and
tear testing should be performed in both machine and transverse directions.
Residual strain in extruded sheeting can cause shrinkage in the machine
direction and expansion in the transverse direction when the sheeting is
warmed. In the manufacture of synthetic fibers, the polymer filament is
drawn from spinnerets as it is being formed from a melt. This process
orients the crystalline domains as they are forming to yield high strength in
the fiber direction. On heating the fiber above the melting point of the
crystals, the fiber will shrink and partially return to its original length.
TABLE 4-3. COMPARISON OF THE COEFFICIENT OF LINEAR THERMAL
EXPANSION OF POLYMERIC COMPOSITIONS WITH OTHER CONSTRUCTION MATERIALS
Coefficient of
Temperature, linear expansion
Material ^C (cm/cm/°C x IP"6)
Polymeric compositions:
Polybutylene ... 125-140
Polystyrene 20-25 70-80
Polypropylene 20-25 81-100
Polyester terphthalate ... 65
Low-density polyethylene 20-25 100-220
Medium-density polyethylene ... 140-160
High-density polyethylene ... 110-130
Polyethylene/vinyl acetate ... 160-200
Natural rubber 17-25 77.0
Nylon 6 ... 80-83
Polyvinyl chloride:
Ri gi d
Flexible
Nonpolymeric materials:
Al umi num
Steel
Concrete
Glass
50-100
70-250
40 23.13
40 13.22
10-14
10
Sources: Lange, 1972; Moore and Kline, 1984; Modern Plastics
Encyclopedia, 1980-81.
4.2.1.8 Multiaxial Straining of Polymer Materials--
In actual service the components of a liner system are strained multi-
axially because stress is simultaneously applied to the component in two or
more directions. This multiaxial straining reflects the irregularities in
4-11
-------
the surface on which the component is placed, the uneven loads that are ap-
plied, and the irregular shapes of the components. This is in contrast to
the, uniaxial straining encountered in laboratory tests, e.g. tensile tests,
which are normally used for specification and quality control purposes in
assessing lots or batches of the polymeric component. A unaxial test, such
as normally used in measuring tensile properties, generally gives unreal-
istically high elongations at break compared with those encountered in
service for many of the polymeric materials, particularly those that yield or
draw on extension, such as the PE FMLs. In biaxial and multiaxial tests,
the materials that are extended in one direction have considerably lower
elongations and tensile values in the transverse direction as they break or
split at the much lower elongation in that direction. Multiaxial straining
is discussed more fully in Section 4.2.2.4.2.
4.2.1.9 Broad Range of Permeability--
The permeability of the polymeric sheetings to various gases and vapors
can vary over several orders of magnitude. Generally, the presence of plas-
ticizers in the compound increases permeability and the presence of crystal-
line structure reduces permeability. Also of importance is the relationship
between the solubility characteristics of the permeant and the polymer; the
more soluble the permeant is in the FML, the higher the probability of
permeation. The permeability of polymeric FMLs is discussed more fully later
in this chapter.
4.2.1.10 Polymers are Sensitive to Organic Liquids and Vapors--
As the polymeric compositions used in liner systems are organic in
nature, they are sensitive to organics, which they can absorb from waste
liquids and vapors. They can swell or, if they contain soluble fractions,
can be leached and shrink. In either case, depending on the material several
properties (e.g. tensile strength, modulus, permeability) of the composition
can simultaneously change and the performance characteristics can be altered.
The sensitivity of polymers to organics indicates the need for compatibility
testing, which is discussed in Chapter 5.
4.2.1.11 Resistance to Stress-Cracking and Static Fatigue--
Polymeric materials, as with many other materials, are subject to
loss of strength and to fracture when under mechanical stress for extended
periods of time. Some semi crystalline polymeric compositions, e.g PE and
PEL, when placed under stress in chemical environments in which the surface
of some grades of a material is affected by a chemical species present, can
crack or craze in moderately short times. Thus, the resistance of FMLs of
semi crystal line polymers that might be used in contact with waste liquids
over long periods of time should be assessed along with that of the seams of
the FMLs. Environmental stress-cracking (ESC) resistance is discussed in
greater detail in Section 4.2.2.5.4 which is concerned with tests to measure
the effects of environmental exposure. The subject of stress-cracking
resistance and methods of assessing this property testing are presented by
Howard (1964).
4-12
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4.2.1.12 Effects of Long-Term Exposure—
In the development of polymeric compositions for construction materials,
long service life under adverse environments was a major objective in their
selection, design, and formulation. With proper protection through the use
of stabilizers, antioxidants, and other antidegradants, polymers used in the
manufacture of FMLs, geosynthetics, and pipe can be highly resistant to
degradation and sustain essentially no adverse change in molecular structure
when exposed underground and in normal weather. Nevertheless, polymeric
compositions are still subject to loss in properties due to swelling by
water and organic solvents which separate the polymer molecules and reduce
strength and increase permeability. Generally, however, molecular structure
of a polymer remains essentially undamaged by swelling alone, as is shown by
the return to its original properties when the swellant is removed, though
some polymers may interact with the waste.
Polymer molecules in polymeric compositions have been found to be highly
resistant to biodegradation, though some compounding ingredients used in
their formulation, such as some plasticizers, may be biodegradable. Current
technology in the manufacture of polymeric FMLs include the use of biocides
which have proven to be effective in inhibiting or eliminating biodegradation
of plasticizers. If not protected by a biocide, biodegradation may result in
adverse changes in the properties of the composition. The use of many of the
polymeric construction materials in environments that have a high potential
for microbial activity, e.g. MSW landfills, is of major concern to engineers
in designing structures that call for extended service lives, e.g. 40 to 100
years. The presence of microbial action has been found to have no effect on
many synthetic polymer molecules over long periods of time. The nonbiode-
gradability of polymers, such as polyethylene, has been further demonstrated
by the fact that these same synthetic polymers used in packaging have created
problems in disposal as they do not degrade and become part of the biomass by
natural processes. Considerable research effort has been devoted to develop-
ing methods of degrading these materials by microbial activity.
Research and testing have indicated that, under conditions in which the
antioxidants have been removed, thin polymeric films subjected to soil-burial
have shown indication of degradation through loss in tensile strength. In a
series of tests performed by Colin et al (1981) on soil-burial of extracted
1-mil film, the sensitivity to biodegradation increased from polyester and
polypropylene to low- and high-density polyethylenes to Nylon 66. The
authors point out that the results did not eliminate the possible presence
of residual antioxidants in the polypropylene or efficient oxidation in-
hibitors in the polyethylenes. Albertsson (1978) has shown that pulverized
antioxidant-free polyethylene compositions placed in nutrient media have
shown indications of oxidative degradation.
A review of the literature with respect to biodegradation of synthetic
polymers and the development of biodegradable polymers (Potts, 1978; Schna-
bel, 1981; Kumar et al, 1983) indicates the following generalizations which
4-13
-------
account for the high resistance to biodegradation and biodeterioration of the
polymers and polymeric materials that are discussed in this chapter:
- Carbon-chain polymers, such as PE, PP, and PVC, are particularly
resistant to biodegradation. Nylon, with nitrogen in the chain, has
been found to be biodegradable under certain circumstances.
- The susceptibility of a polymer to biodegradation decreases with
increasing molecular weight. The polymers used in the manufacture
of geosynthetics and pipe have molecular weights in the thousands;
consequently, they are beyond the range of the polymers that can be
assimilated and metabolized by enzymes and microorganisms. Ethylene
oligomers (low molecular weight polymers) up to 32 carbons in length
can be absorbed and metabolized by microbes, but higher molecular
weight PEs cannot be either absorbed or metabolized.
- Microorganisms appear to attack polymer chain ends, which are inac-
cessible in the mass of a polymeric composition, particularly in
those polymers that are semicrystalline. Orientation of semicrystal-
line polymers into fibers makes the ends more inaccessible and in-
creases resistance to biodegradation.
- Polymers are insoluble in water which makes them inaccessible to
water-borne enzyme systems.
- The state of subdivision is an important factor in the biodegradation
of polymers. Reduced surface area reduces the accessibility of the
polymers to microorganisms, such as in the case of FMLs or pipe.
- The susceptibility of polymers to biodegradation is reduced or in-
hibited by molecular chain branching.
- Biodegradation processes are retarded or inhibited by a variety of
additives, such as antioxidants.
- Exposed groups on the surface, e.g. chlorine, can be attacked but
not similar groups below the surface of the polymer product.
- The rates of biodegradation depend greatly on environmental condi-
tions, many of which probably do not exist in the environment of
FMLs and other components in service. For instance, it has also
been found that, in the absence of oxygen, even among natural bio-
degradable polymers, there has been little or no degradation.
The service life in landfill environments of FMLs and other synthetic
polymeric materials of construction used in liner systems was the subject
of discussion of a panel of polymer experts held by the EPA (Haxo and Haxo,
1988).
4-14
-------
The panel reviewed potential degradation of polymeric materials by
such means as thermal degradation (i.e. heat), photodegradation (i.e. light,
particularly UV light), high energy radiation, biodegradation, chemical
degradation, and mechanical stress with particular reference to environmental
conditions under which polymeric components of lining systems would function.
All types of polymers used in the manufacture of components for liner
systems were considered. Polyethylene compositions, which are used to manu-
facture FMLs, geonets, geotextiles, and pipe, were often emphasized in the
discussion because of their wide use in these products.
Some of the principal conclusions drawn from the information available
to the panel were:
- The basic conditions to which polymeric FMLs and other components of a
liner system are exposed in both MSW and hazardous waste landfills
include comparatively low ambient temperatures, lack of light, mois-
ture, aerobic and anaerobic atmospheres depending on the component of
the liner system and the location within the fill, and low concentra-
tions of dissolved constituents. In limited situations, higher
temperatures (e.g. 90°C) in some radioactive wastes, are encountered.
Thus, polymeric materials placed in service in liner systems do not
generally encounter the types of conditions that are normally con-
sidered to cause degradation of the base polymeric resins.
- The particular polymers used in the manufacture of products for the
construction of landfill liner systems will not degrade in the en-
vironments they will encounter in landfills because of the lack of
highly aggressive conditions that would cause degradation. These
polymers include the polyethylenes, modified olefinic polymers, and
some polyesters.
- The polymers under discussion and first-grade compounds of these
polymers should maintain their integrity in landfill environments
for considerable lengths of time, probably in terms of 100's of years.
Nevertheless, when these polymers or compounds are used in products
such as FMLs, drainage nets, geotextiles, and pipe, they are subject
to mechanical and combined mechanical and chemical stresses which may
cause deterioration of some of the important properties of these
polymeric products in shorter times.
4.2.1.13 Combinations of Properties in Polymeric Compositions--
A given polymer will tend to have a distinct pattern of mechanical,
chemical, and aging properties which can, within limits, be modified by
compounding. Assessing materials based upon a single property, such as
tensile strength, can lead to an inadequate selection of a material for
a given application because of changes in the values for other unmeasured
important properties, such as chemical resistance. Also, the effects on
4-15
-------
different properties of the polymeric composition to aging and exposure can
differ greatly. For this reason, a group of properties of a polymeric
material are usually measured and the resulting property values are reviewed
as a group before a selection is made.
4.2.2 Polymeric Flexible Membrane Liners (FMLs)
The first polymeric FMLs were based on butyl rubber (Lauritzen and
Peterson, 1953); since then, a wide variety of FMLs based on different poly-
mers have become available. Sheetings are produced by calendering, extru-
sion, or spread-coating processes. Sheetings made by calendering are some-
times fabric reinforced to improve tear strength and dimensional stability
during installation. Sheetings made by spread-coating are fabric reinforced.
Many polymeric FMLs are produced in relatively narrow sheetings that are
seamed in the factory to make large panels which are transported to a con-
struction site, where they are seamed to form the liner. Some of the FMLs
made by extrusion processes are prepared in width up to 33 ft, which can be
brought in rolls to the field for installation.
The following steps are involved in the manufacture of polymeric FMLs
through installation in the field:
- Production of the basic polymer or polymers.
- Compounding of the polymer.
- Manufacture of the sheeting.
- Fabrication of narrow sheeting into panels.
- Installation in the field of panels or rolls of sheeting to form the
liner.
An individual organization may perform one or more of these steps, depending
on the material and the company. Figure 4-5 illustrates the structure of the
FML industry. Appendix C presents a representative list of organizations
and personnel in the individual segments of the industry.
This section discusses various aspects of the technology of poly-
meric FMLs, particularly with respect to their use as lining materials for
waste storage and disposal facilities. The different types of polymers used
to manufacture all currently available FMLs are described and discussed.
Polymers that have been used and are currently in service are described in
Appendix C which includes information on various polymers used to manufacture
the FMLs and membranes that were studied in the work reported in this docu-
ment. Some of these were developmental materials. The processes used in
the manufacture of polymeric FMLs are briefly described and illustrated.
Critical steps involved in liner installation, such as field seaming of the
membranes, are also described. The principal properties of FMLs essential to
their function as a lining material are discussed. The methods of assessing
polymeric membranes for lining waste storage and disposal facilities are then
discussed.
4-16
-------
RAW MATERIAL
PRODUCERS
Polymers
• Plastics
• Rubbers
Fabrics
• Square
MANUFACTURERS OF FMLS
Compounding
Forming Process
Calendering
Extrusion
Spread coating
Other Ingredients
• Filters/Pigments
• Plasticizers
• Crosslinkers
• Stabilizers
• Processing aids
FMLS
• Thermoplastic
• Semicrystalline
• Crosslinked
• Fabric reinforced
Narrow Sheeting
(< 90 inches)
FABRICATORS-
Factory assembly of
FMLS into panels
Wide Sheeting
(21-33 feet)
in rols
Panels
(< 20,000 sq. ft.)
INSTALLERS
Assembly on site of panels
or rols into iners wlh field seams
Lined Waste Containment Facilities
Owners
• Cities/counties
• States
• Industrial
• Landfill operators
• Federal, e.g. mitaiy
Types
• Landfills
• Ponds
• Lagoons
• Pits
• Reservoirs
• Canals
• Dams
Figure 4-5.
Basic structure of the polymeric FML industry from raw material
producers to liner installers. A representative list of or-
ganizations and personnel in the individual segments of the
industry is presented in Appendix B.
4-17
-------
4.2.2.1 Polymers Used in Currently Available Polymeric FMLs--
A wide range of polymeric FMLs have been used to line waste storage
and disposal facilities. For a variety of reasons, both economic and techn-
ical, a number of the FMLs have been discontinued and are no longer avail-
able. The polymers described in this section are those that are used in
currently available FMLs; the remainder are described and discussed in Ap-
pendix C. Each of these materials has a history of use for lining contain-
ment and conveyance facilities. Table 4-4 lists the different types of pol-
ymers that have been used in the manufacture of FMLs, and indicates whether a
given polymer was used in vulcanized or unvulcanized form, and whether or not
FMLs based on the given polymer were manufactured with fabric reinforcement.
Those polymers that are discussed in Appendix C are indicated.
TABLE 4-4. POLYMERS USED IN MANUFACTURE OF FMLS
Type of compound
used in FMLs
Thermo- Cross-
Fabric
reinforcement
Polymer
Butyl rubber (polyisobutylene-
isoprene rubber-IIR)a
Chlorinated polyethylene (CPE)
Chlorosulfonated polyethylene (CSPE)
Elasticized polyolefin (ELPO)a
Elasticized polyvinyl chloride (PVC-E)
Epichlorohydrin rubber (CO, ECO)a
Ethyl ene propylene rubber (EPDM)a
Neoprene (chloroprene rubber-CR)a
Nitrile rubber (NBR)a
Polyester elastomer (PEL)
Polyethylene (PE)
Polyvinyl chloride (PVC)
plastic
No
Yes
Yesb
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
linked
Yes
Yes
Yes
No
No
Yes
Yes
Yes
—
No
No
No
With
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
Without
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
—
Yes
Yes
Yes
aFMLs based on these polymers are not currently available. These
polymers discussed in Appendix C.
bMade and used as a thermoplastic but contains a small amount of curative
which crosslinks the compound during exposure.
4-18
-------
The physical and chemical properties of polymeric FMLs vary consider-
ably, as do methods of installation and seaming, costs, and interaction with
different wastes. The composition and properties of FMLs of a given generic
polymer type can differ considerably, depending on the compound formulation.
Polymers are rarely used alone in a product; whether used singly or in
blends, they are usually compounded with a variety of ingredients (e.g.
fillers, plasticizers or oils, antidegradants, and curatives) to improve
either selected properties or the balance of properties depending on end-use
and to reduce compound cost. Properties of a polymeric FML also depends on
its construction e.g. its thickness, whether or not it is fabric reinforced,
the type of fabric reinforcement used, and the number of plies. Because the
grade and source of polymers of a given generic type vary, differences
between FMLs also arise from the polymer itself. Successful use of a polymer
in some environments may require specific compounding.
Most compounds used in the manufacture of lining materials are based on
one polymer; however, to improve specific properties of a compound, two or
more polymers are at times blended or "alloyed." Consequently, generic
classifications of lining materials based on individual polymers are some-
times difficult to make, even when one polymer predominates in a compound.
Most polymeric FMLs are now based on uncrosslinked compounds and, therefore,
are thermoplastic. This is true even for membranes that use crosslinkable
polymers such as CPE and CSPE, which become more chemically resistant by
crossl inking. Thermoplastic FMLs have become preferred because they are
easier to seam and repair effectively during installation in the field.
Thermoplastic FMLs can be seamed by various heat sealing or welding methods.
If they are noncrystalline, they can be seamed with various adhesives and
neat solvents or "bodied" solvents (a solvent containing dissolved liner
compound to increase the viscosity and reduce its rate of evaporation).
In the following subsections each polymer is discussed with respect to
composition, general properties and characteristics, general use, and use in
membranes. Whenever appropriate, an indication is made of the use of a given
polymer in blends with other polymers compounded specifically for lining
purposes.
4.2.2.1.1 Chlorinated polyethylene—Chlorinated polyethylenes (CPE)
form a family of polymers produced by chlorinating high-density polyethylene.
They contain 25-45% chlorine and 0-25% crystallinity. CPE can be crosslinked
but, in liner compositions, it is generally used as a thermoplastic and is
compounded with either oil or plasticizer, and with such fillers as carbon
black and various fine inorganic powders. CPE is often blended with other
polymers, but to be classified as a CPE FML, at least half the polymer
content must be CPE. Polyvinyl chloride (PVC) or chlorosulfonated poly-
ethylene (CSPE) is sometimes added to a CPE compound to improve its tensile
and thermal properties.
4-19
-------
Because CPE is a completely saturated polymer (it has no double bonds,
-C=C-, in the polymer chain which are points of chemical attack), most CPE
compositions resist weathering well on outdoor exposure and are not sus-
ceptible to ozone cracking. CPE FMLs can be formulated to withstand in-
termittent contact with aliphatic hydrocarbons and oils, but continuous
exposure to aromatics shortens the service life of this liner material. In
most cases, CPE liners are not recommended for containment of aromatic
liquids (Dow Chemical Company, 1977).
CPE can be "alloyed" in minor amounts with PVC, PE, and numerous syn-
thetic rubbers. It is blended in minor amounts with ethylene polymers to
soften them and to improve their resistance to environmental stress-cracking,
and with flexible polyvinyl chloride to improve cold crack resistance.
CPE FMLs are available in both unreinforced and fabric-reinforced
versions of different thicknesses. Because CPE FMLs are generally not cross-
linked, they can be seamed by bodied-solvent adhesives, solvent-welding, or
heat sealing by air-heat guns, hot wedge welders, or dielectric means.
4.2.2.1.2 Chlorosulfonated polyethylene--Chlorosulfonated polyethylenes
(CSPE~)form a family of saturated polymers (no double bonds in the polymer
chain) prepared by treating polyethylene (in solution) with a mixture of
chlorine and sulfur dioxide. Available CSPE polymers contain from 25-43%
chlorine and from 1.0-1.4% sulfur. The CSPE most commonly used in membrane
liner manufacture contains 25% chlorine and 1.0% sulfur. Membranes are
supplied primarily in the thermoplastic (uncrosslinked) form; however, they
contain a minor amount of metal oxide which causes the compound to crosslink
in the presence of moisture. Two versions of CSPE sheetings are available:
(1) a "potable" grade which contains magnesium oxide, and (2) an "industrial"
grade which contains a lead oxide or other lead compounds. Both oxides are
crosslinking agents, but the lead oxide imparts a faster and tighter cure to
the CSPE than does the magnesium oxide. Of the two grades, the industrial
grade swells less on contact with industrial wastes. The FML compound of
both grades generally contains at least 45% of CSPE polymer by weight.
When properly formulated, CSPE compositions are characterized by ozone
resistance, light stability, heat resistance, good weatherabi1ity, and
resistance to deterioration by such corrosive chemicals as acid and alkalies
(DuPont, 1979). CSPE compositions have good resistance to growth of mold,
mildew, fungus, and bacteria, but only moderate resistance to oils and many
organic chemicals.
CSPE FMLs are almost exclusively manufactured with fabric reinforcement.
Though some of the early CSPE FMLs were reinforced with nylon fabric, CSPE
FMLs are reinforced now with polyester fabrics. Of these fabrics 10 x 10
scrim predominates, but 8x8 and 6x6 types have also been used. Fabric
reinforcement improves dimensional stability and gives needed tear strength
to the sheeting for its installation and use on slopes; fabric also reduces
distortion of the sheeting by shrinkage whenever it is exposed to the sun.
Unreinforced CSPE FMLs have low tensile strength and tend to soften and
shrink on exposure to sunlight and heat.
4-20
-------
Unexposed thermoplastic CSPE FMLs can be seamed while thermoplastic by
radiant heat sealing, dielectric heat sealing, hot-air guns, heated wedges,
solvent welding, ultrasonics, or with "bodied-solvent" adhesives. FMLs based
on this polymer resist cracking and failure at low temperatures as well as
weathering, even when exposed without a soil cover. Since thermoplastic CSPE
FML tends to crosslink when exposed to ultraviolet radiation or to heat and
moisture, repairing damaged sheeting that has been aged can be difficult
because the crosslinked material is not readily soluble and is no longer
thermoplastic. Moderate aging can result in a skin cure that will require
abrasive treatment to remove the cured skin and allow seaming with a bodied
solvent. Highly aged sheeting, that is completely crosslinked, has been
satisfactorily seamed for some purposes with a proprietary adhesive.
4.2.2.1.3 Polyester elastomers—Polyester elastomers (PELs) form a
family of melt-processable segmented thermoplastic copolyester elastomers
containing recurring polymeric long chain ester units derived from dicar-
boxylic acids and long chain glycols and short chain ester units derived
from dicarboxylic acids and low molecular weight diols. They are both semi-
crystalline and thermoplastic, covering a durometer hardness range of 92 on
the "A" scale to 72 on the "D" scale (ASTM D2240). The PELs combine high
modulus, elasticity, and low temperature flexibility with oil, fuel, chemical
and biodegradation resistance. These polymers were introduced commercially
in 1972.
Polyester elastomer derives its strength from crystallizable polyester
blocks which form crystalline regions or domains that are dispersed in an
amorphous matrix. The melting point of these crystalline domains is around
400°F, which indicates serviceability to relatively high temperatures. PELs
have good tear and abrasion resistance, along with high resilience.
The commercial polyester elastomers that are used in the manufacture of
FMLs have hardnesses in the range of 50 to 65 durometer hardness on the "D"
scale. FMLs based on PEL are fabric reinforced and are manufactured by
calendering or by extrusion. Because PELs are thermoplastic, seams of PEL
FMLs are usually prepared by thermal methods and rarely with adhesives.
4.2.2.1.4 Polyethylene—PEs are a family of semi crystal line polymers
that are based principally on ethylene. They range from liquids to hard
plastics and have a range from a few hundred molecular weight to hundreds of
thousands molecular weight. The basic mechanical properties of a specific PE
are determined largely by molecular weight and crystallinity, as indicated in
Figure 4-6.
Polyethylenes are produced by various polymerization processes and with
a variety of catalysts. These processes and catalysts may be varied to
produce polymers which have been classified in a long-standing practice by
ASTM D1248:
4-21
-------
Type of Range of density,
polyethylene Name g/cm^
Type I Low-density polyethylene (LDPE) 0.910 to 0.925
Type II Medium-density polyethylene 0.926 to 0.940
(MDPE or LLDPE)
Type III High-density polyethylene (HOPE) 0.941 to 0.959
Type IV High-density polyethylene (HOPE) >0.960
Note: The liner industry has not been following the ASTM clas-
sification and is using the term "HOPE" loosely to cover
the PE polymers that are classified as "MDPE" or "LLDPE"
by ASTM. The designation "HOPE" is being used in most of
the technical and trade literature relating to these
products and in EPA documents. At this point, to avoid
confusion in terminology, the use of the term "HOPE" is
continued in this Technical Resource Document to describe
the medium- and high-density types of PE FMLs and other
HOPE geosynthetics that are commonly used in the liner
industry. It is recommended, however, that the desig-
nations of PE presently used in the manufacture of these
products should follow ASTM D1248 designations. This
means that almost all of the resins currently being
employed should be called MDPEs. The term "HOPE" should
be used solely to designate those resins that fall under
the classification of PE Type III and IV of ASTM D1248.
It is recognized, nevertheless, that due to production, sampling, and
testing variables, there is variation in the density of polyethylene of a
given type that is manufactured; the accepted tolerance range is ±0.002 g
cm~3 of the normal value of density.
The oldest and most common of the polymerization processes is a high
pressure process which produces highly branched polymers having lower density
and low crystallinity. This is a Type I PE, also designated as LDPE. At the
high end of the density range, the Type IV HDPEs are prepared at low pressure
and are homopolymers of ethylene with no measurable side branches.
Type II and Type III PEs are made in a variety of processes in which
ethylene is polymerized with controlled ammounts of a comonomer, such as
1-butene, 1-hexene, or 1-octene. These produce short branches of ethyl,
butyl, or hexyl-side branches, respectively. As the number of side branches
incorporated into the ethylene backbone increases, the density of the PE
decreases. Thus, it may be possible to have polymers having similar molecu-
lar weights and densities produced by entirely different polymerization
and/or catalyst routes.
4-22
-------
Hard
*
ra
t/5
O
in
UJ
100
8°
IV
40
20
Stiff
Liquids
j_
0.96
0.95
0.94
0.93
0.92
0.91
0.90
-------
Dp = density of compound, and
C = weight percent of carbon black in the compound.
In addition to the carbon black, PE FMLs contain antioxidants to improve
aging and UV resistance; they also may contain a variety of additives such as
antiblock agents, slip agents, and other processing aids. The PE base resins
often contain trace metal residues from the polymerization catalysts.
Density of PE resin
Polymerization process
Molecular structure
Low
High pressure
Branched with
long chains
Medium
Low pressure
Linear with
short chains
» 1
•
ii I
i
Short-chain branches
Long-chain branches/
molecule
30
High
Low pressure
Linear with a
few small side
chains
C2,C4
0
Figure 4-7. Schematic comparision of the structures of PE and ethylene
copolymers of different densities; C = number of carbon
atoms in the short chains.
The high crystallinity of the PEs compared with many other polymeric
compositions used in manufacturing FMLs results in polymers that are parti-
cularly resistant to swelling and permeation by many liquids, gases, and
vapors. However, some of the higher density PE FMLs are subject to environ-
mental stress-cracking (ESC), which is discussed in Section 4.2.2.5.4.
Basically, it has been observed that FMLs based on PE resins having densities
in excess of 0.942 g cm" 3 will generally not meet FML performance require-
ments for resistance to ESC (Dewsnap et al, 1986).
Several means have been used to increase the environmental stress-
cracking (ESC) resistance of HOPE; they include increasing molecular weight,
the blending of HOPE with various elastomers, such as EPDM, butyl, and
CPE (Howard, 1964), and the copolymerization of ethylene with a-olefins
(terminally unsaturated) such as 1-butene, 1-hexene, and 1-octene. The
blending of EPDM with HOPE has been used commercially in the manufacture of
an FML with substantially better ESC resistance than the HOPE alone. This
blend was termed "HDPE-A". FMLs based on this blend were used for several
years. However, at the present time (June 1988), the manufacture and use of
HDPE-A have been discontinued as PEs with better ESC and solvent resistance
have been developed using copolymers of ethylene and a-olefins.
4-24
-------
The forming of PEs into sheeting for use as FMLs is done principally
in an extrusion process, as described in the section of this chapter on
processing. As PEs are thermoplastic and semicrystalline, they soften and
melt when heated above their respective melting points in the range of 120°
to 140°C; therefore, seaming of PE FMLs can be performed by various thermal
methods. All of these methods require that the surfaces be cleaned and free
of oxidized polymer and be melted so that the molecules in both FMLs that are
being joined can molecularly mix. If a molten extrudate from a welder is
used to join the FMLs, the extrudate should melt both surfaces and then
molecularly mix with the surfaces of both FMLs. The extrudate should be
based on the same PE compound and have the same density as the FMLs it is
joining.
4.2.2.1.5 Polyvinyl chloride—Polyvinyl chloride (PVC) is produced from
vinyl chloride monomer by any one of several polymerization processes. It is
a versatile thermoplastic polymer that is compounded with plasticizers and
other modifiers to yield compositions with a wide range of physical prop-
erties from flexible rubber-like materials to hard plastics.
PVC FMLs are generally produced by calendering in various widths and
thicknesses. Most PVC FMLs are unreinforced, but they can be reinforced with
fabric. PVC FML compounds contain 25% to 35% plasticizer to make the flexi-
ble and rubber-like sheetings. They also contain 1% to 5% of a chemical
stabilizer, and various other additives, including colorants. A wide variety
of plasticizers are used in PVC sheeting; the choice of plasticizer depends
on the application and service conditions under which the sheeting is used.
Plasticized PVC FMLs have good mechanical properties: tensile strength,
elongation at break, and puncture and abrasion resistance. As they are
thermoplastic, they can be seamed by solvent and thermal methods.
PVC FMLs have been the most widely used polymeric FMLs. They have
good resistance to many inorganic chemicals (Chan et al, 1978). Although
the polymer inherently resists the effects of oils, many organic chemicals
(hydrocarbons, solvents, and oils) attack PVC sheetings plasticized with
monomomeric plasticizers, e.g. the phthalates which are biodegradable. PVC
compounds that possess high resistance to oil attack can be prepared with
special polymeric plasticizers. For example, polyester plasticizers and
polymers, such as nitrile rubber, CPE, and ethylene vinyl acetate (EVA), can
be used to replace the extractable monomeric plasticizers, and thus make PVC
compositions that are more resistant to many waste liquids. Some of these
compositions may have less low temperature resistance compared with those
with monomeric plasticizers.
Because the PVC resins are sensitive to ultraviolet light and need to be
plasticized, a PVC liner, which may contain a volatile plasticizer, should be
covered with soil or other suitable cover to protect it. Carbon black is
often used as an ultraviolet stabilizer, but, because it makes the sheeting
black, the temperature of the sheeting is raised when exposed to the weather
and plasticizer evaporation is increased. In some burial tests and in some
liner applications, PVC FMLs have become stiff due to loss of plasticizers to
the soil and biodegradation by microorganisms. Monomeric plasticizers can
4-25
-------
also be extracted somewhat by water or long-term exposure. Plasticized PVC
can be protected against biodegradation (biodeterioration) by a broad spec-
trum of macroorganisms to varying degrees through the use of biocides or
biostabilizers.
4.2.2.2 FML Manufacture--
4.2.2.2.1 Compounding of FML compositions--Most polymeric membranes
are based on single polymers, but blends of two or more polymers are being
developed and used in liners. Also, different grades of a given type of
polymer can be used. Generic classifications based on individual polymers
have become increasingly difficult even though one polymer may predominate.
All polymers are compounded with auxiliary ingredients which serve
different purposes. The basic compositions of the different types of com-
pounds are shown in Table 4-5. The crosslinked compositions are usually the
most complex because they contain a crosslinking system. Thermoplastics,
except for CSPE compounds, contain no curatives. Although supplied as
thermoplastic, CSPE liners contain crosslinking agents that allow the polymer
to crosslink during service. Crystalline materials have the simplest com-
position and generally consist of the polymer, a small amount of carbon black
for ultraviolet protection, antidegradants, and possibly processing aids.
TABLE 4-5. BASIC COMPOSITIONS OF POLYMERIC
FML COMPOUNDS
Component
Composition of compound type,
parts by weight
Cross- Thermo- Semicrys-
1 inked3 plastic9 talline
Polymer or alloy
Oil or plasticizer
100
5-40
100
5-55
100
0-10
Fillers:
Carbon black 5-40
Inorganics 5-40
Stablizer/inhibitor 1-2
Crosslinking system:
Inorganic system 5-9
Sulfur system 5-9
5-40
5-40
1-2
2-5
• • •
1
Available in unreinforced and fabric-reinforced
versions.
bAn inorganic curing system that crosslinks over
time is incorporated in CSPE FML compounds.
4-26
-------
Several of the auxiliary components of a formulation can be affected
during service when they are either immersed in the liquid or exposed to
the weather. Low molecular weight fractions in the base resin or blend can
be lost. The oils and plasticizers are potentially extractable and, in some
cases, biodegradable; some stabilizers can be extracted. Loss or change in
any of these components can affect properties and durability of the compound.
Most of the FMLs currently manufactured are thermoplastic. Though FMLs
based CPE or CSPE are more chemically resistant in the crosslinked form than
in the thermoplastic form, they are generally supplied as thermoplastics,
which are easier to seam reliably and to make repairs in the field. Thermo-
plastic FMLs can be heat-sealed or seamed with a solvent, bodied solvent, or
special adhesives. Semi crystal line FMLs are generally seamed by thermal
welding or fusion methods.
FMLs of all but the semi crystal line type compositions are available with
fabric reinforcement which increases strength and thermal stability. The
fabric constructions vary from thread counts of 6 x 6 to more than 20 x 20.
As the thread count increases, the area between the threads that allows con-
tact between the plies is reduced. The adhesion between plies is dependent
upon this area and good "strike-through" and "knitting" of the polymeric
layers during manufacture. Good initial ply adhesion and its retention
during service are important to prevent delamination.
4.2.2.2.2 Forming processes—A variety of FMLs manufactured by dif-
ferent processes for different materials as illustrated in Figure 4-8.
<
Various Types uf
Figure 4-8. Various types of polymeric FMLs available for
lining applications.
4-27
-------
The three basic methods used in the manufacture of polymeric sheeting
for liner use are calendering, extrusion, and spread or knife coating.
Calendering is used in forming both unreinforced and fabric-reinforced
sheeting, whereas extrusion is only used in making unreinforced sheeting.
Spread coating is used for making fabric-reinforced sheeting in which the
fabric is comparatively tight, i.e. the number of thread ends per inch is
greater than 20.
Calendering is the most common method of forming thermoplastic FMLs. It
is also used in forming vulcanized rubber FMLs. In this process, heated
rubber or elastic compounds are passed between the heated rolls of a calender
to form a sheet of predetermined thickness. A calender usually consists of
three to four rolls, as is shown in Figure 4-9. Unreinforced sheeting is
usually of single-ply construction; however, some manufacturers have used
multiple plying of unreinforced liners to eliminate the formation of pinholes
through the sheet. By manufacturing sheeting in this manner, the probability
of a pinhole in one ply coinciding with a pinhole in another is remote.
However, del ami nation of the plies has occurred on long immersion in waste
liquids and some organic solvents.
Vertical
Offset top roll
(a)
Inverted L
Vertical
Figure 4-9.
Roll configuration of calenders: (a) three-roll calenders,
and (b) four-roll calenders (Blow, 1971).
4-28
-------
Fabric can be placed between the plies of the polymeric compound to
reinforce the FML. In this case, sufficient material must be placed on
both sides of the fabric so that pinholes are not generated between the
fabric and the outside of the sheeting. Also, there should be sufficient
compound present to strike through the open weave of the fabric and achieve
direct contact of the rubber on both sides of the fabric. Fabric reinforce-
ment is usually achieved through the use of open fabrics or scrim of nylon,
polyester, polypropylene, or glass fiber. The thread count or ends per inch
usually range from 6 x 6 to 10 x 10 per inch, but most are 10 x 10 ends per
inch. Figure 4-10 shows several types of fabric. A coating is applied to
the finished fabric after weaving in order to tack the yarns in place so that
the finished fabric construction pattern will not lose its shape. Different
coating formulations are used, depending on the end use. Fabrics to be used
with vulcanized elastomeric FMLs are usually treated with an adhesive coating
which chemically reacts with the FML compound during the curing cycle to
produce adhesion to the polymer compound.
Extrusion methods are used primarily in the manufacture of PE and other
semi crystalline FMLs. For the thinner FMLs and films, it is common to form a
tube of the FML or film and to slit it to form a lay-flat sheet. For the
thicker gage PE FMLs flat sheets are extruded directly with different equip-
ment. For example, as shown in Figure 4-11, a large circular die extruder
can produce FMLs 22 ft in width. Flat extruders can produce sheeting up to
10 to 12 ft in width and a proprietary extruder is capable of producing
sheeting up to 33 ft in width.
Some manufacturers set up special straining operations to clean out
grit that may be in the compound. This operation immediately precedes the
calendering or extrusion. In this step, grit and other coarse particles are
screened out to yield a grit-free compound for the calender or extruder.
Spread coating is performed only on fabrics having high numbers of
thread ends per inch. In this process, the coating compound is applied as a
viscous "dough" made of a high concentration of the compound dispersed in a
solvent. The fabric is first passed over a spreader bar to remove wrinkles
and creases and then passed beneath a stationary blade which spreads the
compound and controls the thickness of the polymer coating. The solvent is
evaporated by drawing the coated fabric through a heated chamber and the
solvent is recovered. Upon removal from the heated areas, the sheeting is
cooled and rolled (Blow, 1971, p 285).
4.2.2.3 Seaming of Polymeric FMLs--
Critical to the effective performance of FML liners of impoundments and
solid waste landfills is the construction of continuous watertight barriers
of approximately uniform strength. According to the available information,
seams appear to be the most likely source of FML problems and failures.
As is indicated in the above subsection, many polymeric FMLs, particularly
those made by calendering, are manufactured in relatively narrow widths,
i.e. less than 90 inches. Sheets are cut from the rolls and seamed together
in the factory to make large panels. These panels, in turn, are assembled at
4-29
-------
Manufacturer F. 30 mils tO.76 mm). B-5602. Photo
P222-D-65685
Manufacturer A. 60 mils (1.52 mm). B-4606. Photo
PX-D-68886
Manufacturer G. 30 mils (0.76 mm). B-5540. Photo
PX-D-6E887
Manufacturer H. 30 mils (0.76 mm), B-5560. Photo
PX-D-68888
Figure 4-10. Won-relnforced^butyl lining samples showing different weaves
manufacturers at 6X magnifica-
4-30
-------
the construction site to make large, continuous liners which can range up to
many acres in area. Therefore, a liner installed in this manner contains
both factory and field seams. In the favorable factory environment, durable
seams can be made by a variety of methods depending on the type of polymer.
Several types of FMLs are made in extrusion processes in wider sheetings,
i.e. in widths ranging from 21 to 33 feet; these FMLs are brought to the
site in large rolls and seamed in the field, thus eliminating factory seam-
ing. Seaming in the field can pose difficulties, largely due to variability
in the ambient conditions.
Figure 4-11.
Extrusion of polyethylene FML using an
die. Courtesy of Poly-America, Inc.
extruder with a circular
4-31
-------
In order to function as a liner, an FML must be capable of being bonded
by one or more bonding systems which can produce bonds that are strong and
chemically resistant and meet the following requirements:
- The bond should be based on primary chemical bonds.
- The bond between the sheets must approximate the strength of the
sheeting and must maintain its strength throughout the service life of
the sheeting.
- The seaming process should not damage or degrade the parent FML, such
as weakening the FML at the edge of the weld.
- The bond between the sheets or panels must be continuous for the
length of the seam.
- The bond must be capable of being formed in the field.
The principal requirement of the bond is that the polymeric molecules
of the two FMLs being joined become molecularly mixed without the inclusion
of dirt or oxidated particles, and the interface essentially disappears so
that the mass at the original interface becomes homogeneous. This can be
accomplished either by the use of solvents to dissolve the polymer on both
sides of the interface and allow the molecures to mix or to melt the polymer
and allow the molten polymer from both FMLs to mix before the seams harden or
crystallize as they cool. A residual interface may allow waste liquid to
enter and destroy the adhesive bond.
A variety of bonding systems are used in the seaming of FMLs. Selection
of the optimum system for a given FML will depend largely on the polymer.
Certain techniques or seaming systems are incompatible with certain FMLs.
For instance, dielectric seaming requires polarity in the polymer; therefore,
it cannot be used to seam polyethylene FMLs. Furthermore, because of the
specialized equipment required, the use of dielectric seaming is restricted
to the factory. In addition, adhesives are generally designed for use with a
specific FML and should not be used with other lining materials even though
the two materials may be based on the same polymer. Manufacturers may
recommend a specific seaming technique, a specific type of adhesive, or a
variety of techniques or adhesives.
•
Seaming techniques that are currently used either in the factory to
fabricate panels of thermoplastic FMLs, or in the field to assemble the
panels or rolls of FMLs into a final liner, or both, include the following:
- Solvent methods:
Solvent "welding" with neat solvents.
Bodied solvents.
Special adhesives.
4-32
-------
- Thermal methods:
Heat gun.
Heat sealing.
Dielectric seaming.
Extrusion welding.
Hot wedge.
Ultrasonic.
Table 4-6 presents a list of the possible alternative methods for seam-
ing polymeric materials depending upon the polymer, type of compound, and
location of seaming, i.e. factory or field. Also indicated on the table are
the systems included in the exposure tests. Figure 4-12 illustrates the
configuration of the various seams and the methods of seaming that are
used.
4.2.2.3.1 Solvent methods—Because of the solubility of noncrystalline
thermoplastic polymer compositions in appropriate solvents and the lack of
crosslinks, an FML based on a noncrystalline thermoplastic polymer can be
seamed with solvent mixtures or with solvents in which the liner compound has
been dissolved to form a "bodied solvent." Seaming by these techniques is
described below.
Solvent "Welding". Solvent "welding" of noncrystalline thermoplastic
sheetings with neat solvents can be achieved by coating the mating surfaces
of the sheetings with a solvent or a mixture of solvents suitable for the
compound. The two surfaces are then pressed together firmly, e.g. by
"stitching" with rollers on a firm base. The time for such a seam to "cure"
or set up ranges from 5 minutes to an hour, depending on the type of sheeting
and environmental conditions. Up to 28 days may be needed for the solvent
to evaporate completely from within the seam and for it to achieve full
strength. Though this method can be used both in the field and in the
factory, it is sensitive to weather conditions, e.g. temperature, humidity,
and wind. Volatile solvents which may be desirable at lower temperatures
will evaporate too quickly at higher temperatures or may fail under humid
conditions to yield an adequate bond because of moisture condensation.
In forming seams by the solvent-welding method a solvent or blend of
solvents must be chosen for the specific plastic to be bonded (Been, 1971,
p 125; Bodnar, 1962, p 483). The solvent must quickly dissolve the surface
of the FML and impart tack to the sheeting but not totally dissolve it. The
choice of an appropriate solvent is facilitated by knowledge of the volatil-
ity and solubility parameters of the solvent and of the solubility parameters
of the liner composition (Barton, 1975). In making repairs, it is also
necessary to change or refresh the exposed surface to remove dirt, exudation
from the sheeting, e.g., waxes, and moisture. The surface may need to be
abraded and buffed to remove an oxidized layer which may not be soluble.
Bodied Solvents. The use of a bodied solvent to seam thermoplastic
sheets is an adaptation of the solvent "welding" method described above. A
bodied solvent is a solution of the liner compound to be seamed in a mixture
of solvents. The "adhesive" is applied to both surfaces and the two surfaces
4-33
-------
TABLE 4-6 BONDING SYSTEMS AVAILABLE FOR SEAMING POLYMERIC FMLS IN FACTORY AND FIELD
Type
of FML
CPE
CSPE
LDPE
MDPE
-P*
£ HOPE
PEL
PVC
EVA
Type of
compound3
TP
TP
TP/CX
TP/CX
TP/CX
TP/CX
TP
TP/CX
Place
used
Factory
Field
Factory
Fi el d
Factory
Field
Factory
Field
Factory
Field
Factory
Field
Factory
Field
Factory
Field
Solvent
methods
Neat Bodied
X X
X X
X X
X X
• • • • • •
• • • • •
• • • •
• • • • • •
• • • • • •
• • • • • *
X X
X X
• • • • • •
...
Heat
sealb
X
• • *
X
...
X
...
X
• • •
X
...
X
...
X
...
• • •
...
Heat
gun
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Thermal methods
Die- Extrusion
lectricc welding
seaming Lap Fillet
A • • * • • •
••• ••• •••
V
A • • * • • •
• •• ••• •••
X X
• •• ••• •••
X X
... ... ...
X X
• •* ••• •••
• •• ••• •••
A • • • • • •
••• ••• •••
A * • • • • •
••• ••• •••
Hot
wedge
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Ultra-
sonic
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
aTP = thermoplastic; CX = semicrystalline.
bApplication to the FMLs of 20 mil or less in thickness.
cUsed only in the factory with polar polymers.
-------
CONFIGURATION
METHOD OF SEAMING
LAP SEAM
With no adhesive
~ Bonded surface
With adhesive or extrudate
Made by heat sealing,
dielectric sealing, and
solvent welding
Made with bodied solvents,
adhesives, and by extrusion
welding
Ft* Required overlap of fabric
(fabric - reinforced FMLs only)
Made with an adhesive,
heat seaming, dielectric
seaming, solvent welding,
and heat gun
DUAL-BONDED LAP SEAM
Heat weld
Made with dual hot wedge
and hot air seaming methods
Dual-Bonded Lap Seam
FILLET WELD SEAM
Extruded bead
Buffed area
Gum tack
Buffed area
Made by extruding molten
compound of the same
composition as the FML
over the lapped edge;
a gum tack may be used
for holding the edge
of the FML down
Buffed area
Extruded area
Hot tack
Similar to above, except
a heat gun is used to tack
edge of FML
BUTTERFLY SEAM
Made by a special
heat sealing device
WOT TO SCALE
Figure 4-12.
Configurations of seams used in joining FML sheets and panels
and method of seaming. The "tacks" used sometimes in preparing
the fillet-weld seams are not part of the seam under test and,
when possible they are opened before the seam is tested. A cap
strip (not shown) over the upper edge is sometimes used,
especially with fabric-reinforced FMLs.
4-35
-------
are pressed together after becoming "tacky." There should be no surface
"skinning" or drying of the adhesive when the two surfaces are joined.
The major advantage of a bodied solvent over a straight solvent is the
increased viscosity of the solution which allows more control of the evapor-
ation of the adhesive and aids in making seams on a slope. Another advantage
of bodied solvents is that the dissolved polymer fills voids or imperfections
in the surface of the sheeting and thus improves the consistency and strength
of the seams. As with solvent "welding," bodied solvents can only be used
with thermoplastic materials that can be dissolved in a suitable mixture of
solvents.
The bodied-solvent technique can be used to seam sheetings in the
factory and is particularly useful in the field (Haxo, 1983, p 97; Been,
1971, p 132). It has been used considerably in the seaming of CSPE, CPE,
and PVC membranes and in making field repairs during the installation of
these membranes. Testing of seams must wait until the solvent in the seam
has evaporated through the membrane or has been driven out by heat.
4.2.2.3.2 Thermal methods—A variety of thermal seaming methods are
applicable to thermoplastic FMLs which soften, melt, and flow at higher
temperatures to fuse the sheets being joined. The thermoplastics are listed
in Table 4-4. Thermal seaming methods include: heat sealing, heat gun,
dielectric seaming, extrusion welding, hot wedge, ultrasonic, and various
combinations. Factory seams of cured elastomeric FMLs are vulcanized.
Heat Gun. Seaming with a heat gun has been used for all types of
thermoplastic membranes under both factory and field conditions, including
repair of unexposed liners. In this method, high temperature air or an inert
gas, such as nitrogen, is directed between two sheets to melt the surfaces to
be joined. The two pieces are then forced together with pressure and allowed
to cool to form a lap seam (Bodnar, 1962, pp 481-82).
The major advantage of the heat gun method is its broad range of ap-
plication to many thermoplastic materials. The two disadvantages are the
great care required to obtain uniform, reproducible seams and the tendency
of the hot air to oxidize and degrade the surface of the FML during the
seaming process and thus produce a poor bond. This method also requires that
the surfaces to be joined be clean and free of moisture, dust, oil, and all
solvents. These requirements pose problems when seaming in the field,
particularly when seaming FMLs that have been exposed to waste streams and to
the weather.
Heat Sealing. In this thermal seaming method, the heat required to melt
and bond the two layers of thermoplastic is applied through the sheets by
clamping them between a pair of jaws which are quickly and reproducibly
heated, normally by passage of an electrical current through a resistance
wire. The sheets remain clamped for a preset period following cessation of
the current and the molten polymer solidifies to form a lap bond (Been, 1971,
p 158).
4-36
-------
The advantage of heat-sealing is that the complete bonding cycle is
readily controlled by a timer and, thus, seams can be made rapidly and
reproducibly. As exposure of the heated plastic to air is minimal, the
problem of oxidation and embrittlement is reduced.
Another form of heat sealer not sharing the advantages of the clamp
type is a heated roller which can be used manually to simultaneously press
and melt together both sides of the seam (Bodnar, 1962, p 482). Both roller
and clamp heat sealers share a serious disadvantage in that heat must pass
through the seam and, thus, are generally limited in application to rel-
atively thin sheetings. With thicker sheetings, the bonding process is
very slow and the heated surfaces tend to become fluid, flow, and thin down
before the bonding surfaces are sufficiently molten for fusion to occur.
Dielectric Seaming. In dielectric seaming, heat is generated internally
within the pieces of sheeting to be joined by directing electromagnetic
energy in the radio-frequency region to the seam. The energy field oscil-
lates and causes the permanent or induced dipoles in the polymer to oscillate
with the same frequency, creating internal friction and heat. Advantages of
dielectric heating are that the entire cross section of the sheeting is
heated quickly and uniformly, the heating process can be instantly started
and stopped, the method is very efficient as it does not generate waste
heat, and the process is readily controlled and highly reproducible. Pres-
sure is applied until the area being seamed has cooled and a strong bond
formed.
Dielectric seaming can only be used with FMLs based upon thermoplastic
polymers synthesized from easily polarizable monomers. The presence of
water in an exposed FML can result in internal blowing and sponging of the
FML. This technique is suitable only for factory operations where the
environmental requirements of the equipment can be met and cannot be used
in the field. FMLs that can be seamed by this technique are based on such
polymers as PVC, CPE, and CSPE; PEs cannot be seamed by this technique.
Within these limitations, dielectric seaming provides very rapid and reli-
able seaming (Rothstein, 1971, p 161), but it is not suitable for field
seaming of FMLs.
Extrusion Welding. Seaming of HOPE FMLs is being performed in the field
with a variety of proprietary and specially designed seaming equipment based
on the extrusion of molten HOPE of the same composition as the liner either
between the FMLs being seamed to form a lap weld or at the edge of the top
sheet to form a bead or fillet. Also, seaming equipment based on heat guns
has been devised in which coiled plastic welding rods or strips can be melted
and placed. The rod is fed to the seam area to form a fillet-weld seam.
In the first extrusion welding procedure, a jet of hot air is injected
into the overlap area to blow away debris and heat the area to be welded.
Directly following the hot air, a ribbon of molten polymeric compound of the
same composition to that of the sheets being joined is injected into the
overlap through an extruder nozzle. A roller moving behind the extruder
4-37
-------
nozzle presses the overlap together so the sheets will be fused by the ex-
truded ribbon. Welding speed, pressure roller movement, and temperature
are adjustable with the extrusion equipment. The result can be a homogeneous
weld that is immediately load bearing.
In the second extrusion welding procedure, a hand-held extruder, in
which pellets or strips are fed and melted, places a bead or fillet of the
molten PE at the edge of the overlap of the two FMLs that are being seamed.
The surfaces of the FMLs are normally buffed and cleaned prior to seaming;
also, the edge of thicker FMLs are beveled to give greater surface and to
ensure that air pockets are not left at the edge of the top FML. In per-
forming this seam, the top FML is positioned and tacked to the lower FML
through the use of heat guns or gum tape between the two FMLs. This type of
seaming is used both in assembling the FMLs and in the repair and patching of
FMLs.
With extrusion and fusion seaming methods, continuous seams of ex-
tended length can be made in the field at a broad range of ambient temper-
atures. The critical temperature is that of the FML and the extrudate.
Welding can be carried out at sheet temperatures >5°C. With extra measures
such as 1) slowing down welding rate, 2) preheating the sheet, and 3) setting
up wind shields for the welder, welding is possible down to sheet temper-
atures of -15°C. Success at these low temperatures should be verified by
test welds.
Extrusion seaming methods, as with all other seaming methods, require
careful preparation of the surfaces to be bonded (e.g. drying and buffing,
removal of any oxidized layer, as well as proper adjustment of temperatures
at the surfaces of the layers to be joined) to assure blending and molecular
mixing of the polymeric compound at the interface.
Hot-Wedge Welding. The hot-wedge method (Neidhart, 1979) consists of a
hot electrically-heated element in the shape of a blade or V-shaped wedge
that is passed between the two sheets to be sealed. Contacting the two
sheets to be seamed together, the heated element melts, and smears the two
surfaces causing fresh material to come to the surface. Immediately follow-
ing the melting, roller pressure brings the molten surfaces together to form
a homogeneous fused bond.
The hot-wedge method is particularly suited for the thicker [greater
than 30 mils (0.76 mm)] LLDPE and HOPE materials, but it is also used with
the reinforced thermoplastics. Single-hot-wedge and dual-hot-wedge systems
are both available. The dual-hot-wedge weld forms a continuous air channel
between two welds. The air channel can be used as a means of testing the
bond continuity when air pressure is injected into it. Welding rate (move-
ment of the machine) as well as temperature and roller pressure are adjust-
able and continuously monitored. Adjustments are made according to environ-
mental conditions such as ambient temperature and moisture.
The hot-wedge method has been used in both the factory fabrication of
panels and in field installation. It is particularly suited to long,
4-38
-------
continuous, straight seams. However, without special modification, it does
not appear to be suitable for making repairs because of the irregularity of
the shapes required to patch liners.
Ultrasonic Welding—A newly introduced welder for seaming FMLs involves
the use of ultrasonic energy that is designed to dissipate the vibrational
energy at the point of contact of the two FMLs to be seamed, causing the FMLs
to become molten as a result of the heat generated by fractional activity.
Immediately upon melting the membrane surfaces pass through two rollers which
squeeze the two sheets together to create a bond from one to two inches in
width. The welder is mounted on a three-wheel frame. The rollers, which are
motor driven, serve to propel the unit at a controlled rate along the seam
line. This seaming method has been applied to thermoplastic FMLs from 0.010
to 0.125 in. in thickness.
4.2.2.3.3 Other bonding methods for seaming FMLs--In addition to
the seaming methods described above for thermoplastic and semi crystalline
FMLs, other methods are used in the seaming of crosslinked FMLs, i.e.
butyl rubber (IIR), EPDM, CR, and some thermoplastics. Discussions of
these seaming methods are included for information because FMLs currently in
service were seamed by these methods, and because results of research and
testing are reported in this document on materials seamed by these methods.
Hot Vulcanization. High temperature vulcanization was used in the
factory to prepare panels of IIR, EPDM, and CR FMLs. This seaming was
performed under controlled conditions of pressure and time to achieve vul-
canization and bonding across the interface of the two FMLs being joined.
Vulcanizing Adhesives. Vulcanizing adhesives achieve their strength
from the crosslinking or vulcanization of the polymeric base. The vulcani-
zation may be either a long or short-term operation and may occur under
service conditions. Usually, a vulcanizing adhesive is a two-part system,
one containing the polymer base, and the other the crosslinking agents. A
complete system, as supplied by the manufacturer, includes a two-part cement,
a rubber-base gum tape, and a lap sealant; it is designed for use in both the
factory and the field.
Solvent Cements and Contact Adhesives. "Solvent cements" is an expres-
sion used by the adhesive industry to Fefer to any of a large variety of
adhesives that are applied dissolved in a nonaqueous solution. The strength
of the bond is achieved either contemporaneously with or after the volatiza-
tion of the solvent. Thus, a solvent cement can be anything from a solution
of a thermoplastic resin to a contact cement. Two types of solvent cements
are of interest to the lining industry:
- Contact cements.
- Cements that volatilize their solvent while forming the adhesive
bond.
4-39
-------
Surfaces to be bonded by the second type of adhesive are usually pressed
together while the solvent cement is still "wet". Because polymeric membrane
materials can have low permeability to a number of solvents, it is important
to choose a solvent cement based on a solvent that can volatilize out of the
seam assembly. This can happen when the solvent in the cement either dis-
solves or partially dissolves the surface of the sheeting and forms what
might be called an "interpenetrating" bond with the lining material.
Contact cements are adhesives that are applied wet to surfaces of
sheetings that are to bonded and allowed to dry to a "non-tacky" and solvent-
free state before the two surfaces are joined. The use of this type of
adhesive requires careful alignment of the lining material before bonding
because the joined surfaces should not be realigned after assembly. After
joining, the seam should be rolled with a steel or plastic roller in a
direction perpendicular to the edge of the seam.
Based upon meeting safety requirements, solvent cements could be used
either in the field or in the factory to seam FMLs; however, they are more
likely be used only in the field.
Tapes. Tapes have been used in the past to seam FMLs in the field.
They are made with pressure-sensitive adhesive applied either to both sides
of a flexible substrate or to a flexible backing. The latter is removed once
the tape has been placed on one of the surfaces to be joined. Tapes can be
used to hold the sheetings in place while another seaming technique is used,
or they can be used to provide the permanent bond.
Tapes have been used to seam PE FMLs in the field; however, the use of
tapes alone for making seams in FMLs for waste disposal facilities is not
recommended. More recently, they have been used in the positioning of FML
sheets for fillet extrusion seaming.
Mechanical Methods. Mechanical methods for seaming, though adequate for
water containment, are not considered adequate for seaming liners for waste
storage and disposal facilities.
4.2.2.3.4 Repairing and seaming of exposed FMLs--An investigation by
Haxo (1987) indicated that there is no current technology that can be used
to repair leaks and other damage in FMLs that are in service below wastes.
Applying the basic criteria used in assessing and testing liners and seams
in FMLs that are being installed, it appears highly questionable that
conditions required for preparation of adequate seams and permanent repairs
can be met with FMLs exposed below wastes. Liners exposed to the weather
only, e.g. on the slopes of surface impoundments, can be repaired if the
proper conditions of cleanliness and dryness are met. Repairing with formed-
in-place plugs holds some promise for short-term use; however, permeability
and compatibility of the plugging material with the waste liquid should be
assessed.
4-40
-------
4.2.2.4 Properties and Characteristics of FMLs Important
to their Function in Li her Systems--
The principal characteristics of an FML that are important to its func-
tion as a liner for a TSDF include low permeability to waste constituents,
its mechanical properties, chemical compatibility with the waste liquid to
be contained, which is determined by the FMLs' chemical properties, and its
durability for the lifetime of the facility. Laboratory and pilot-scale
tests of FMLs are used to assess these characteristics. In the following
subsections, these characteristics of FMLs are discussed, and test data on
unexposed FMLs are presented.
4.2.2.4.1 Permeabi1ity--The primary function of a liner is to prevent
the flow of mobile liquids and other chemical species. Thus, the permeabil-
ity of an FML to these species must be assessed. As is discussed in Chapter
3, transport through FMLs occurs on a molecular level and depends on the
solubility of the permeating species and its diffusibility in the FML. A
concentration or partial pressure gradient across the FML is the driving
force for the direction and rate of transport. The species migrates through
the FML from higher to lower concentration; thus, at a small difference in
concentration, the transmission can approach zero for specific species. In
contrast, soils and clays are porous and the driving force for permeation is
the hydraulic head. When used below an FML in a composite liner, permeation
through the soil will occur only by diffusion (Chapter 3), if there is no
hole in the FML.
The permeability of FMLs to different species can vary by orders of
magnitude, depending on the composition and solubility of the migrating
species in the FMLs (Haxo et al, 1984a and 1984b; August and Tatzky, 1984).
The permeation of a given species is also affected by such factors as cry-
stallinity, filler content, density, crosslink density of the polymer,
thickness of the FML, temperature, and the driving force across the membrane.
Also, swelling of an FML during service can significantly increase its
permeability to some species.
The different topics discussed in the following paragraphs include the
following:
- Permeability to gases, including the effect of temperature on gas
permeability.
- Permeability to water vapor.
- Permeability to solvent vapor.
- Permeability to organics and organic tracer dyes.
- Permeability to ions and water-soluble tracer dyes.
- Effect of thickness on permeability.
4-41
-------
Gas Permeability. Permeability to gases, particularly methane, is an
important property of polymeric FMLs used to control gas migration from
land storage and disposal facilities (Haxo et al, 1982). FMLs are used
as covers and curtain walls to control movement of methane from landfills
and as barriers to prevent entrance of methane into buildings and other
structures near MSW landfills.
The permeability of FMLs and other membranes to three gases of interest
in land disposal facilities (methane, carbon dioxide, and nitrogen), measured
in accordance with ASTM D1434, Procedure V - Volumetric, was reported by Haxo
et al (1984a and 1984b). In this procedure an FML specimen is clamped into a
stainless steel cell to form a barrier to gas flow. All air is flushed from
the system with the test gas and then one side of the cell is maintained at a
positive pressure while the other remains at atmospheric pressure. A capil-
lary mounted on the atmospheric pressure side of the cell is used to measure
the volume of gas slowly diffusing through the liner. The test apparatus is
shown in Figure 4-13.
Capillary v. - -
Cell top
inlet valve
Gas inlet
Gas bubbler
Cell top
vent valve Cell bottom
vent valve
Figure 4-13.
Gas permeability apparatus in ASTM D1434,
Procedure V - Volumetric.
4-42
-------
Data for the permeability at 23°C of a series of polymeric FMLs to
carbon dioxide, methane, and nitrogen are presented in Table 4-7. Data are
reported as gas transmission rates, which are indicative of FML performance,
and as permeability coefficients, which are material properties and reflect
the permeabilities of the FML compounds. Gas transmission rates (GTR) in
mL(STP)/m2'd*atm are converted into permeability coefficients (P) in barrens
[10-10 mL(STP)-cm/cm2-s-cm Hg] using the following equations (ASTM D1434):
"P = 0.01532 x (thickness in mm) x GTR. (4-2)
The results of the gas permeability measurements show:
- Major differences in gas transmission rates among the FMLs, which
reflect variations in polymer type, compound composition, and thick-
ness. For example, the transmission rates of carbon dioxide, mea-
sured at 23°C with a pressure gradient of 20 psi, ranged from 122
mL(STP)/m2-d-atm for CSPE 6R to 5260 mL(STP)/m2'd'atm for EPDM 91.
- Permeability of FMLs of a given generic polymer type can differ due to
compounding differences (e.g. in filler and plasticizer contents).
For example, the gas permeability coefficient of one CSPE compound
(CSPE 55) to carbon dioxide was 3.6 times greater than the gas
permeability coefficient of the other CSPE compound (CSPE 6R).
- Permeability of a given FML can vary greatly with the gas. For
example, all FMLs had a much greater permeability to carbon dioxide
than to methane or nitrogen, and a greater permeability to methane
than to nitrogen.
- Gas transmission through FMLs of a given composition will decrease
with increased thickness. For example, the two HOPE FMLs were es-
sentially of the same composition. One was a 0.61-mm sheeting, and
the other was a 0.86-mm sheeting. The thinner sheeting had higher gas
transmission rates to the two gases with which they were both tested.
- Higher polymer crystallinity yields lower permeability coefficients,
as is shown by comparing the permeability coefficients of the LDPE,
LLDPE, and HOPE FMLs; all contained carbon black, except the LDPE FML
which was clear.
An FML (ELPO 36) was tested for permeability to carbon dioxide, methane, and
nitrogen at three different temperatures (10°, 23°, and 33°C). The results
are presented in Figure 4-14. Data are reported as GTR for a 0.158-mm thick
specimen under a pressure difference of one atmosphere. These results
show that permeability of a given FML to gases increases with temperature in
accordance with Arrhenius's equation.
Hater Vapor Permeability. The permeability of FMLs to water vapor is
important in a variety of applications, including covering reservoirs and
other impoundments, lining canals and tunnels, and being moisture barriers
in buildings and structures.
4-43
-------
TABLE 4-7. PERMEABILITY OF POLYMERIC FMLS TO GASES AT 23°C,
DETERMINED IN ACCORDANCE WITH ASTM D1434, PROCEDURE V
i
-P*
-Pi
FML description
Polymer
IIR
CPE
CSPE
CSPE
ELPO
EPDM
EPDM
EPDM
CR
PB
HOPE
HOPE
LDPEh
HOPE
LLDPE
PVC
PVC
PVC
PEL1
Serial
number0
44
77
6R
55
36
83R
91
8
90
221
265(0.945)
269(0.945)
21(0.921)
265(0.945)
281(0.923)
93
88
59
• • •
Thickness
mm
1.60
0.72
0.82
0.86
0.58
0.89
0.90
1.50
0.90
0.71
0.61
0.86
0.25
0.61
0.46
0.25
0.49
0.81
0.022
Com-
, pound
typed
XL
TP
TP
TP
CX
TP
XL
XL
XL
CX
CX
CX
CX
CX
CX
TP
TP
TP
TP/CX
Gas transmission rate (GTR),
mL(STPa)/m2-d-atm
C02
512
106e
122
418
1450
2720f
5260
• * •
716
818
729
467
6180f
729
1370
7730f
3010
2840f
357
CH4
120
6.3ie
21.6
124
280
1400
4709
80.9
248
138
104
1340f
138
322
1150f
446
285f
• • •
N2
19.7
1.45e
26.2
27.1
125
• • *
314
• * •
31.1
62.3
• * •
* • •
• • •
• * *
• • •
108
• * •
* • •
Gas permeability
coefficient (P),
barrerb
C02
12.5
1.16e
1.52
5.47
12.8
36. 8f
72.0
• • •
9.81
8.84
6.77
6.11
23. 5f
6.77
9.59
29. 4f
22.4
35. Of
0.119
CH4
2.92
0.0696
0.270
1.62
2.47
• • •
19.2
10.79
1.11
2.68
1.28
1.36
5.10f
1.28
2.25
4.38f
3.32
3.51f
• • •
N2
0.480
0.0166
0.33
0.36
1.10
• • •
4.30
• • •
0.43
0.67
• • •
• • •
• • •
* • •
• • •
0.81
• • •
aSTP = Standard temperature and pressure.
bOne barrer = 10~10 mL(STP)-cm/cm2-s*cm Hg.
cMatrecon liner serial number; R = fabric-reinforced; numbers in parentheses are densities.
dXL = crosslinked; TP = thermoplastic; CX = semi crystal line.
eMeasured at a pressure gradient of 40 psi; all others measured at 20 psi, unless noted.
fMeasured at 30°C.
9Measured at 20°C.
"Natural resin (no carbon black).
Uhis sample is NBS Standard material 1470. The determination was made at 15.0 psi, under which
condition the NBS Certified C02 transmission rate can be calculated to be 338 mL(STP)/m2.d.atm.
-------
3.6
3.4
— 3.2
to
•a
CM
E
3.0
2.8
2.6
O
2.4
c 2.2
O
I 2.0
§ 1.8
1.6
1.4
33°C
I i
23°C
10°C
I
3.0 3.1 3.2 3.3 3.4 3.5
Temperature, K~1 x 103
3.6
Figure 4-14.
Permeability of ELPO to C02,
temperature.
CH4, and N2 as a function of
The water vapor transmission (WVT) rate of an FML is the time rate
of water vapor flow normal to its surfaces under steady conditions through a
unit area under the conditions of test and is reported in grams per square
meter per day (g m~2 d~l). Transmission of 1 g nr^ d~l of water is equal in
practical units to 1.07 gal per acre per day. The water vapor permeance of a
material is the ratio of its WVT to the vapor pressure difference across the
two surfaces. The pressure difference is the saturation vapor pressure of
water at a specific temperature multiplied by the difference in the rela-
tive humidity (expressed as a fraction) across the two surfaces. The unit
of permeance used is metric perm, or g m~2 d~l (mm Hg)~l. The permeance
value of a sheet is a rational basis for evaluating its performance and com-
paring various FMLs of different thicknesses for a given application. The
permeability of an FML is the product of its permeance and its thickness.
The unit used in this report is the metric perm«cm or g m~2 d~l (mm Hg)"l-cm.
The water vapor permeability of a homogeneous FML is a property of the
composition which may vary with exposure conditions. Both permeance and
permeability may vary with exposure conditions.
To assess this characteristic of FMLs,
FMLs were determined in accordance with ASTM
(Procedure BW). In this procedure, a circular
the WVT rates of a range of
E96-80, Inverted Water Method
specimen of FML is sealed with
4-45
-------
molten wax into the mouth of an aluminum cup partially filled with deionized
water. The test cup is illustrated in Figure 4-15. The entire assembly is
kept in an inverted position so that water is in contact with the FML sur-
face, and stored in a cabinet maintained at 23°C and a relative humidity (RH)
of 50+5%. This cabinet is equipped with a small fan to ensure uniform
air velocity over the surfaces of the specimens as required by the procedure.
Thus, the WVT occurs across a water vapor pressure gradient of 100% RH
(inside the cup) to 50% RH in the cabinet.
Wax Seal
FML
Retaining Ring
Aluminum Container
Figure 4-15.
Exploded view of water vapor transmission cup used in ASTM
E96-80. In the test procedure, the cup is kept in an inverted
position so that water sealed in the cup contacts the FML
surface.
The test cups are periodically weighed, and the resulting data (7 to
14 data points in the straight line portion of the weight-time curve) are
reduced using linear regression to yield a loss rate which can be converted
to a WVT value in units of g m~2 d~l. WVT data for a series of FMLs, repre-
senting different material types and materials produced by different manu-
facturers, are presented in Table 4-8 by polymer and increasing thickness.
The calculated values of water vapor permeance and water vapor permeability
are also presented.
4-46
-------
TABLE 4-8. PERMEABILITY OF POLYMERIC FMLS TO WATER VAPOR3
FML description
Polymer
Butyl rubber
CPE
CSPE
ELPO
ECOd
EPDM
EVA
Serial
number''
164
57
22
86
142
135
145
77
38
12
136R
147R
152R
165
169R
148
3
55
151R
173R
6R
149R
174R
170R
172
36
178
178
41
83
26
163R
18
8
308
Thickness,
mm
1.15
0.85
1.85
0.53
0.76
0.79
0.79
0.79
0.82
0.85
0.91C
0.94C
0.97C
0.97
0.74C
0.76
0.79
0.89
0.91C
0.94C
0.94C
0.97C
0.99C
1.07C
0.61
0.72
1.16
1.65
0.51
0.94
0.97
0.85C
1.23
1.70
0.53
Com-
pound
type
XL
XL
XL
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
CX
CX
XL
XL
XL
XL
XL
XL
XL
XL
TP
Water vapor
transmission
rate,
g m"2 d"1
0.053
0.020
0.097
0.643
0. 36-. 063
1.400
0.294
0.320
0.361
0.264
1.470
0.305
0.557
0.643
0.333
0.663
0.634
0.438
0.748
0.481
0.422
0.397
0.523
0.252
0.144
0.142
20.18
14.30
0.270
0.190
0.327
0.384
0.314
0.172
1.57
Water vapor
permeance,
10'2 metric perm
0.503
0.190
0.921
6.10
3.42-5.98
13.3
2.79
3.04
3.43
2.51
14.0
2.90
5.29
6.10
3.16
6.29
6.02
9.49
7.10
4.57
4.01
3.77
4.96
2.39
1.37
1.35
192
136
2.56
1.80
3.10
3.64
2.98
1.63
14.3
Water vapor
permeability,
10"2 metric perm-cm
0.0579
0.0161
0.170
0.324
0.260-0.454
1.05
0.220
0.240
0.281
0.213
1.27
0.272
0.513
0.592
0.234
0.478
0.475
0.845
0.646
0.429
0.377
0.366
0.492
0.256
0.083
0.097
22.2
22.4
0.131
0.170
0.301
0.310
0.367
0.278
0.760
Continued . . .
4-47
-------
TABLE 4-8. (Continued)
Polymer
Neoprene
FML description
Serial Thickness,
number^ mm
42 0.51
43 0.80
168 0.91
167R 1.27C
82 1.55
9 1.59
Com-
pound
type
XL
XL
XL
XL
XL
XL
Water vapor
transmission
rate,
g irr2 d~l
0.304
0.448
0.473
0.429
0.240
0.237
Water vapor
permeance,
10"2 metric perm
2.89
4.25
4.49
4.07
2.28
2.25
Water vapor
permeabil ity,
10~2 metric perm-cm
0.147
0.340
0.409
0.517
0.353
0.358
Nitrile rubber 171R
PBe
PELf
LDPE
HOPE
HDPE-A
PVC
PVC-E9
PVC-ORh
Saran film
(0.5 mil)
Teflon film
(4 mil)
220
221
75
314
108
184
179
181
89
17
88
19
137
146
11
143
176R
177R
144
40
59
222
234
0.76C
0.19
0.69
0.20
0.25
0.76
0.80
2.44
0.86
0.28
0.51
0.52
0.54
0.74
0.76
0.76
0.79
0.91C
0.97C
0.79
0.83
0.84
0.013
0.10
TP
CX
CX
CX
CX
CX
CX
CX
CX
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
5.51
0.401
0.084
10.50
43.7
0.0573
0.0172
0.0062
0.0472
4.42
97
94
78
10
94
1.85
1.85
2.78
1.94
3.47
4.17
4.20
0.563
0.217
52.3
3.81
0.797
99.7
41.5
0.544
0.163
0.059
0.448
42,
28,
27,
26,
10,
18,
17,
17,
26.4
18.4
32.9
39.6
39.9
5.34
2.06
3.98
0.0723
0.0550
1.99
10.6
0.0413
0.0131
0.0144
0.0385
1.17
1.44
1.45
1.42
0.77
1.40
1.33
1.39
2.40
1.79
2.60
3.28
3.35
0.00695
0.00206
ASTM E96-80, Procedure BW: Inverted water method at 23°C; 50% humidity on downstream side.
Permeance in metric perms - g m~2 d~l (mm Hg)~l = WVT/ip in mm Hg, where ip = the vapor
pressure difference = 10.53 mm Hg (at 23°C and 50$ humidity on downstream side). Permeability
in metric perms-cm = permeance x thickness of FML in cm.
^Matrecon serial number; R = fabric-reinforced.
cThickness is not corrected to exclude thickness of reinforcing fabric.
dECO = epichlorohydrin rubber.
ePB = polybutylene.
fpEL = polyester elastomer.
9Elasticized PVC.
"Oil-resistant PVC.
4-48
-------
As with the gas permeability data, permeability to water vapor varies
considerably among the polymer types; for example, the rates are much lower
through hydrocarbon types (e.g. butyl rubber, EPDM, and ELPO) than through
polar types (e.g. ECO and nitrile rubber). Increased thickness and increased
crystallinity, in the case of semi crystal line materials, reduce permeability
rates. Also, within a polymer type there is considerable variation due to
differences in composition. Thus, even though an FML may be thicker than
another FML of the same generic polymer type, it does not necessarily have a
reduced transmission rate. For example, the thinnest CSPE FML (169R) had the
second lowest transmission rate of the 10 CSPE FMLs tested.
Solvent Vapor Permeability. Considerable data exist with respect to the
transport of organics through polymeric films (Yasuda, 1966; Yasuda et al,
1968), but only a few data exist with respect to polymeric FMLs (Haxo et al,
1984a and 1984b; August and Tatzky, 1984). Preliminary experiments were
performed with neat solvents to assess their transmission rates under con-
trolled conditions through different FMLs. Solvent vapor transmission (SVT)
rates were determined in accordance with a procedure based on ASTM E96-80,
Inverted Water Method (Procedure BW). In this procedure, a circular specimen
of an FML is mechanically clamped onto the mouth of an aluminum cup partially
filled with the test solvent (Figure 4-16). The method differs from the
procedure used to measure WVT described above in that the cups are stored in
an upright position so that only solvent vapor contacts the FML specimen.
SVT occurs as a result of the concentration gradient across the specimen by
the presence of a saturated atmosphere within the cup and the essentially
zero level outside the cup. Thus, the vapor pressure difference across the
FML specimen is equal to the vapor pressure of the test solvent at the test
temperature (i.e. at 23°C). The SVT rate is determined as described above
for WVT.
Screw
FML
Sealing Rings
Aluminum Container
Figure 4-16. Exploded view of SVT cup with aluminum sealing rings,
4-49
-------
SVT rates for a series of FMLs selected for test because of their good
solvent resistance to five organic solvents (i.e. methanol, acetone, cyclo-
hexane, xylene, and chloroform) are presented in Table 4-9. Also presented
in Table 4-9 are the values for solvent vapor permeance (calculated by
dividing the SVT by the vapor pressure difference) and solvent vapor perme-
ability (calculated by multiplying the solvent vapor permeance by the thick-
ness of the respective FML specimens). Although limited, the data show
substantially different transmission rates among the FMLs and among the
different solvents. Increased crystallinity among the polyethylene FMLs
reduces transmission, as does increased thickness. HOPE that has been
alloyed with another polymer to reduce environmental stress-cracking has
significantly higher vapor transmission and permeability than the unalloyed
HOPE.
Permeability to Organics and Organic Tracer Dyes. Using organic dyes
as tracers has been suggested as a means of detecting the presence of holes
in FMLs. The question arises whether an FML might allow a tracer to permeate
a hole-free FML and thus falsely indicate the presence of a hole.
The pouch test appears to be an appropriate method to assess the
permeability of selected FMLs to organics and organic tracer dyes. In this
procedure, small quantities of a test liquid are sealed in pouches fabricated
from FMLs. The pouches are immersed in deionized water (DI) or another
liquid of known composition. Transmission through the pouch walls is moni-
tored by changes in weight of the filled pouch, chemical analyses (including
pH and conductivity measurements) of the liquid outside the pouch, and the
appearance of the dyes in the outer liquid or on the pouch surface. The
pouch procedure is presented in Appendix D.
Haxo and Nelson (1984a) reported on the use of the pouch test procedure
to obtain data on the permeation of three semi crystalline FMLs (HOPE, HDPE-A,
and PB) to selected organics and organic tracer dyes. The procedure used in
these tests differs from that presented in Appendix D. The pouch size was
reduced so that the pouches could fit into wide-mouth glass quart jars which
were used to contain the pouches and the outer liquid. Jars were used in-
stead of polybutylene bags to prevent the pouches from floating in the outer
liquid. Specific FMLs were selected for test because of their low solubility
in organics, because of their low extractables contents, and because they
could be fabricated into leak-proof pouches relatively easily by heat-sealing
of the seams. The two organics selected for this study were xylene and
acetone. Five different solutions were prepared at 1% dye concentration.
These solutions were:
- Automate Red in acetone.
- Automate Red in xylene.
- Methyl Violet in 50:50 solution of acetone and water.
- Fluorescent Yellow in acetone.
- Fluorescent Yellow in xylene.
4-50
-------
I
tn
TABLE 4-9. PERMEABILITY OF POLYMERIC FMLS TO VARIOUS SOLVENTS,
MEASURED IN ACCORDANCE WITH ASTM E96, PROCEDURE BW (MODIFIED) TO TEST SOLVENTS
Polymer
Liner number
Thickness, mm
Type of compound
SVT, g m-2 d'1
Methyl alcohol
Acetone
Cyclohexane
Xylene
Chloroform
CSPE
170R
1.07-1.12
TP
• • •
221
• * •
• • •
• • •
ELPO
172
0.53-0.61
CX
2.10
8.62
7.60
359
3230
HOPE
184
0.77-0.83
CX
0.16
0.56
11.7
21.6
54.8
179
2.42-2.81
CX
• • •
• • •
• • •
6.86
15.8
180
0.53
CX
• • •
• • •
• • •
295
• • •
HDPE-A
181
0.85-0.88
CX
0.50
2.19
151
212
506
182
0.97
CX
• • *
• • •
• • •
220
• • •
LDPE
108
0.74-0.76
CX
0.74
2.83
161
116
570
PB
221
0.64-0.74
CX
0.35
1.23
616
178
2120
Teflon
234
0.10
CX
0.34
1.27
0.026
0.16
20.6
Solvent vapor
permeance3, 10~2
metric perms
(SVT/mm Hg)
Methyl alcohol
Acetone
Cyclohexane
Xyleneb
Chloroform
Solvent vapor
permeability0, 10'2
metric perms*cm
104
1.88
4.07
8.54
5130
1810
0.14
0.26
13.1
308
30.8
97.9
8.88
4210
0.45
1.03
170
3020
284
3140
0.66
1.33
181
1650
320
0.31
0.58
692
2540
1191
0.30
0.60
0.03
2.28
11.6
Methyl alcohol
Acetone 11.4
Cyclohexane
Xyleneb
Chloroform
0.11
0.23
0.49
292
103
0.01
0.02
1.05
24.6
2.46
• • •
• • •
• • •
25.6
2.32
0.04
0.09
14.7
223 262
24.6
0.05
0.10
13.6
304 124
24.0
0.02
0.04
47.8
175
82.2
0.003
0.006
2.9 x 10-4
0.002
0.12
aVapor pressure of the solvents for permeance calculations was calculated by the Antoine equation using the varia-
bles from Table 10-8, Vapor Pressures of Various Organic Compounds, in Lange's Handbook of Chemistry (Dean, 1979).
The vapor pressures in mm of Hg at a standard room temperature of 23°C are methyl alcohol 112, acetone 212,
cyclohexane 89, and chloroform 178.
bVapor pressure of 7 mm of Hg, which is the average of the individual values for o-xylene, m-xylene, and
p-xylene (Dean, 1979), was used in the calculations since the solvent used was a mixture of the three isomers.
cThe median thickness value was used to calculate the permeability.
-------
Table 4-10 presents information on the dyes used in this study. The
Automate Red B and Fluorescent Yellow were selected for this study to in-
vestigate the possibility of their permeation of an HOPE FML used to line a
series of cells in which the permeability of various soils to waste liquids
was being studied. These dyes, which are soluble in organics but not in
water, were added to the organic wastes so that the flow of these liquids
through soil liner specimens could be observed. During monitoring of the
cell, leakage was observed outside the HOPE liner. It was desired to
determine whether the leakage was by permeation or through holes in the
liner. The Methyl Violet was selected because of its solubility in both
water and acetone.
TABLE 4-10. ORGANIC DYES USED AS TRACERS IN POUCH EXPERIMENTS
Dye
Color
index number
Color
Solubility
Description
Automate Red B Solvent red 164 Red
Fluorescent Yellow Solvent red 175 Brown oil
Petroleum products Proprietary AZO dye
Xylene, acetone
Organic, proprietary
yellow-green fluorescence
Methyl violet
680
Yellow at pH 2 to 3.1 Water, alcohol, C25H3QC1N3
Violet at pH >3.1 chloroform, acetone
The 20-mil HDPE-A FML
crystalline and resistant
could be fabricated from
was selected for this study because it was semi-
to the solvents, and because a leak-free pouch
it with the heat-sealing equipment available.
The filled pouches were placed in either distilled water or in the same
solvent sealed in the respective pouch. Testing was performed in duplicate.
By placing a pouch in the same solvent that was sealed in the pouch, perme-
ation of the dye could be observed. The pouches were monitored principally
for changes in weight. The odor of the outer liquids in the jars was also
noted as well as any appearance of the dyes either on the surface of the
pouches or in the outer liquid. Data on the HDPE-A pouches are discussed
below.
The weight changes of the filled HDPE-A pouches are presented in Figures
4-17 and 4-18, as a function of time. The xylene and acetone with the dis-
solved organic dyes migrated through the walls of all of the HDPE-A pouches.
The pouches which contained the xylene-dye solutions and which were placed
in pure xylene increased in weight (Figure 4-17). This increase in weight is
partially due to absorption of xylene by the pouch wall, but it is primarily
due to the permeation of xylene into the pouch. The dye in the xylene in the
pouch permeated the liner into the outer xylene, which was indicated by the
red color in the outer xylene in the case of the Automate Red and by the
fluorescence of the outer xylene in ultraviolet light in the case of the
Fluorescent Yellow.
4-52
-------
Xylent odor, pouch turf act
red, ted on turfact of outer
at 1 d
60
100 150 200 250
Time exposed, days
300
350
450
500
a. Pouches of 20-mil HDPE-A 180 filled with xylene and 1% Automate Red.
Pouches 154 (D) and 155 (O) were immersed in xylene. Note the movement
of xylene into the pouch. Pouches 152 (O) and 153 (A) were immersed
in DI water. Note the movement of xylene out of the pouch.
I-6
O .g
-10
-12
-14
-16
P126. P127
- Fluorescence in outer
xylene at 1 d
POUCHES IN XYLENE
- Fluorescence on pouch,
oily layer on water
at Id
Fluorescent film on
outer water at 48 d
POUCHES IN Dl WATER
Pouch flat at 224 d
o 0
•"••••
200 300
Time exposed, days
b. Pouches of 20-mil HDPE-A 180 filled with xylene and 1% Fluorescent
Yellow. Pouches 126 (D) and 127 (O) were immersed in xylene. Note the
movement of xylene into the pouch. Pouches 124 (O) and 125 (A) were
immersed in DI water. Note the movement of xylene out of the pouch.
Figure 4-17. Weight changes of HDPE-A pouches filled with xylene immersed
in xylene or DI water.
4-53
-------
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-------
In the case of the HDPE-A pouches containing xylene and which were
placed in water, the xylene migrated out of the pouch into the water but,
because xylene is sparingly soluble in water, it floated to the top of the
outer water. The Fluorescent Yellow dye permeated the pouch wall and,
because it is a solid and insoluble in water, it precipitated on the outside
surface of the pouch. The outer water did not fluoresce in UV light.
In the case of the HDPE-A pouches containing acetone with Fluorescent
Yellow dye and which were placed in water (Figure 4-18a), the acetone also
permeated the pouch wall; but, because acetone is totally miscible with
the water, it dissolved in the water to form a dilute solution. The dye
also permeated the pouch wall, but precipitated on the outer surface causing
it to fluoresce under UV light. When acetone was the outer liquid, the dye
permeated into the outer acetone but the pouches did not change in weight.
This behavior indicates that the pouch walls did not absorb acetone, which
was verified when the pouches were dismantled.
The 20-mil HDPE-A pouches containing a 50:50 mixture of acetone and
water were placed in both acetone and DI water to assess the effects on
concentration on transmission rates. Changes in weight of the pouches up
to 300 days are shown in Figure 4-18b. The pouches in water lost weight,
leveling off as the acetone concentration in the pouch dropped and that in
the outer water increased. The pouches placed in the acetone as the outer
liquid gained weight as the acetone permeated into the pouch. However, the
rate of transmission did not appear to change significantly as the con-
centration of acetone in the pouch increased. No sign of Methyl Violet
was noted in the outer liquid for the pouches in acetone or in water.
The initial rate at which the acetone in the 50:50 mixture permeated
through the HDPE-A membrane into the outer water was less than half that
of the acetone in the pouch with the 100% acetone (compare Figures 4-18a
and 4-18b). Calculated rates are, respectively, 1.68 vs 5.68 g m~2 d~l
for the losses of acetone from the pouch. These results show how a con-
centration gradient can affect rates of transmission through an FML.
The transmission rates of acetone and xylene through HOPE, HDPE-A, and
PB FMLs resulting from the pouch test are compared with solvent vapor and
water vapor transmission data in Table 4-11. These results show a correl-
ation between the pouch data and the SVT data, particularly for acetone.
The xylene transmission data resulting from the pouch test may be low,
possibly due to the low solubility of xylene in water.
This pouch method appears to be a,useful method for assessing the
permeability of FMLs to various organic liquids that may be stored under-
ground and require secondary containment.
Permeability to Ions and Water-Solubie Tracer Dyes. The permeability of
FMLs to inorganic ions and water-soluble organic dyes has been reported by
Haxo and Nelson (1984a). These materials may find use as tracers in testing
the watertightness of a liner system. The pouch procedure appears to be a
means of determining whether tracers could permeate a specific FML. Brown
et al (1983) used tracer dyes to follow flow through soils.
4-55
-------
TABLE 4-11. TRANSMISSION RATES OF ACETONE AND XYLENE THROUGH
FMLS OBTAINED BY THE POUCH TEST COMPARED WITH SVT AND WVT
Polymer
FML number
Nominal thickness, mil
Analytical properties
Specific gravity
Extractablesa, %
HOPE
184
30
0.951
0.73
HDPE-A
180
20
0.949
2.09
PB
221
30
0.907
3.68
Pouch testb
Acetone, g nr2 d'1 -0.866C-A -6.53C-A -1.316C-A
-5.68d-A
50:50, acetone:
water, g nr2 d"1
Xylene, g nr2 d'1
SVT (ASTM E96-66, Procedure
BW, modified)
Xylene, g m~2 d~l
Acetone, g m~2 d~l
WVT (ASTM E96-66,
Procedure BW)
WVT, g m-2 d'l
...
-1.788d-X
21.6
0.56
0.0172
(32 mil)
-1.686-A
+2.09e,f-A
-16.84d-X
-8.48C-X
295
2.199
0.0472
(34 mil)
• • •
-4.40d-X
178
1.23
0.084
( 30 mi 1 )
aln accordance with Matrecon Test Method 2 (Appendix E) using
methyl ethyl ketone as the solvent.
^Transmission rates from pouch into outer liquid indicated by
negative sign, i.e. loss of weight by the pouch. Transmis-
sion values were determined graphically from data in the
early portion of the pouch weight-time curves. The liquids
permeating the pouch walls are represented by the following
symbols: A = acetone; X = xylene. Except where indicated
otherwise, pouches were immersed in deionized water.
cWith Automate Red (1%).
dWith Fluorescent Yellow (1%).
eWith Methyl Violet (1%).
f Acetone was outer liquid.
for HDPE-A 181, a 30-mil nominal thickness sheeting of
the same composition as FML-180.
4-56
-------
Three water-soluble tracers were tested in FML pouches in accordance
with the procedure presented in Appendix D. The tracers included one in-
organic salt (lithium chloride) and two water-soluble organic dyes (Fluo-
rescein and Sevron Red). Lithium chloride is generally found only in
trace amounts in soil and has been suggested as a tracer to detect leaks in
waste impoundments. The dyes have been used for tracing water flow.
Information on the dyes included in this study is given in Table 4-12. The
combinations of pouches that were tested and the liquids loaded into them
are listed in Table 4-13. All the pouches were placed in individual con-
tainers filled with DI water.
TABLE 4-12. WATER-SOLUBLE TRACER DYES USED IN POUCH EXPERIMENTS _
Color Solu-
Dye index number Color bility Description
Fluorescein-sodium Acid yellow 73 Yellow-red Water
green fluorescence in
neutral or alkaline
solutions
Sevron Red ... Red Water Proprietary cationic
dye
TABLE 4-13. COMBINATIONS OF AQUEOUS TEST LIQUIDS
CONTAINING WATER-SOLUBLE TRACERS AND FMLS IN POUCH EXPERIMENTS
FML
Nominal Tracer
thickness, Lithium chloride Fluorescein Sevron Red
Polymer Number mil 5% 10% 1% 1%
PVC
PVC
HDPE-A
PB
137
146
180
221
30
30
20
30
X
X
...
* * *
X
X
...
• * •
X
X
X
X
...
...
X
X
The pouch assemblies were monitored regularly by measuring the weight
of the pouches, measuring the pH and electrical conductivity of the outer
liquids, and by visual observation with normal and UV light for the perme-
ation of the dyes. The weight changes of the PVC pouches containing 5 and
10% solutions of Lid are shown in Figure 4-19.
4-57
-------
200 300 400
Time exposed, days
500
600
a.
Pouches of PVC 137. Pouch 106 contains 5% Lid, and Pouch 107 contains
10% LiCl.
8
7
0)
-- 6
I •
c
-------
After 573 days of exposure, the pouches of PVC with the LiCl solutions
had increased in weight in differing amounts depending on the concentra-
tion of the LiCl in the pouch and the specific PVC FML. The pouches with
a 10% concentration of LiCl increased in weight at twice the rate of the
pouches with the 5% LiCl solution. These results show how a concentration
gradient can affect the rate of transmission. On the other hand, the elec-
trical conductivity of the outer water exhibited almost no change during this
period (up to a maximum of 23 umho cm~l against a background conductivity
of 7 ymho cm'1). These results indicate that water passed through the
pouch walls into the pouches, but little if any lithium chloride passed
through the pouch walls into the outer water. These results indicate that
ions do not permeate this FML in spite of their solubility in water which
does permeate.
All six pouches with 1% aqueous solution of sodium flourescein showed
indications of transmission of the dye through the pouch walls, particularly
in the case of the PVC 146 pouch. Under UV light, fluorescent specks showed
on the surface of some pouches, in scratches, and at corners where the
sheeting had been thinned during heat-sealing. Observation under UV light
also indicated that a small amount of the organic dye permeated the PVC 146
wall since there was distinct fluorescence of the outer water. When the pH
of the outer water was increased, traces of fluorescence appeared under UV
light for all pouches. The gains in weight of the filled pouches were very
small.
In the case of the HDPE-A and PB pouches that contained 1% aqueous
solution of Sevron Red, no signs of dye appeared in the outer water or on
the outside of the pouches after 440 days of test. The weight gains of the
pouches were small, i.e. 0.20 g for HDPE-A pouches and 0.32 g for the PB
pouches. Based on the weights of pouches that were dismantled, it appeared
that the weight gains were in the pouch walls, presumably by absorption of
outer DI water. Overall, the results indicate that Sevron Red probably does
not permeate the walls or does so at a very slow rate.
Effect of Thickness on Permeability. In calculating the permeability
of an FML, a value for permeability is usually obtained for a unit thickness,
e.g. 1 cm of sheeting. This calculation assumes that the transmission is
inversely proportional to the thickness of the sheeting as indicated by
Fick's law for diffusion. In a study of the permeability of various FMLs to
organics, August and Tatzky (1984) observed that the transmission of neat
organics through a series of HOPE FMLs of different thicknesses deviated from
this relationship, as is shown in Figure 4-20. Consequently, extrapolating
from permeability data for a thin film to obtain data on a thicker film would
lead to transmission values higher than those that would result from testing
of the thicker film. A similar effect was observed in the methane perme-
ability of HOPE FMLs of different thicknesses on measurements made at 23°C by
Matrecon, as is shown in Figure 4-21.
4.2.2.4.2 Mechanical properties—The mechanical properties of an FML
indicate its physical characteristics. The most important of these prop-
erties include tensile properties, both uniaxial and multiaxial, and the
4-59
-------
150
140
130
120
110
^ 100
E go
O)
I 80
cc
I 70
1 60
50
40
30
20
10 -
Trichloroethylene
Tetrachloroethylene
Chloroform
Toluene
>' Carbon
f Tetrachloride
'•— Xylene
Chlorobenzene
Iso-octane
_L
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8
Reciprocal of FML Thickness, mm'1
Figure 4-20. Transmission rates of various hydrocarbons as a function of the
reciprocal of the thickness of HOPE FMLs. (Based on August and
Tatsky, 1984, p 166).
ability to resist puncture and tearing. These properties are involved in an
FML's use in the design of an installation and are important in meeting the
installation's engineering requirements. The test methods used to measure
these properties are discussed in detail in Section 4.2.2.5, "Testing and
Laboratory Evaluation of FMLs." However, it should be noted that, at pre-
sent, there is no correlation between the results of these tests and actual
field performance. This subsection discusses how service conditions can
4-60
-------
160
140
120
.§ 100
cu
sr so
w,
E
O
60
40
20
10 20 30 40
Reciprocal of FML Thickness, in."1
50
Figure 4-21.
Gas transmission rate of methane at 23°C through HOPE vs
reciprocal of FML thickness.
4-61
-------
affect certain mechanical properties as measured by specific test methods.
Specifically, this subsection discusses:
- The effect of temperature on properties.
- The effect of rate of deformation on puncture resistance.
- The effect of thickness on puncture resistance.
- The effect of lubrication on puncture resistance.
- Multiaxial stress-strain behavior of FMLs and comparison with
uniaxial stress-strain behavior.
Effect of Temperature on Properties. As indicated in the general dis-
cussi"on on polymers, ffie characteristics of these materials are generally
more sensitive to temperature than the more conventional materials of con-
struction. The flexible type of polymeric compositions, such as the FMLs
used in the construction of waste storage and disposal facilities, are
particularly sensitive to temperature. FMLs, which generally contain carbon
black as protection to UV light, can often reach 60-80°C (140°-160°F) in hot
weather during installation and service. Furthermore, most polymeric FMLs
are thermoplastic and, consequently, can lose considerable strength and
stiffness at such temperatures. With FMLs of some polymers, particularly
those of CSPE, the loss of strength and modulus is so great that it is
necessary to use fabric reinforcement. At elevated temperatures and during
direct exposure to sunlight, there can be considerable creep in an FML and
thinning where it is stretched over sharp points, e.g. rocks and stones.
Care must be taken through proper design to minimize the occurrence of such
damage during installation and in service. The strength and other properties
of an FML at these temperatures can be important factors in its proper
installation.
In two separate studies performed by Matrecon, the tear resistance and
tensile properties of 15 FMLs were tested at elevated temperatures. In the
first study, five different HOPE FMLs were tested at room temperature and at
40°, 60°, and 80°C. In the second study, 10 unreinforced thermoplastic FMLs
were tested at room temperature and at 60°C. These 10 FMLs included three
CPE, one CSPE, four PVC, and two PVC-OR FMLs.
In the first study, five HOPE FMLs were tested at room temperature and
at three elevated temperatures. Three of these FMLs were received from one
supplier and two from a second supplier. FMLs from foreign and domestic
productions were received from both suppliers, as is shown below:
Nominal Matrecon
thickness, mil liner number Supplier Source
30 269 A Domestic
60 185 A Foreign
70 266 A Domestic
90 262 B Domestic
100 288 B Foreign
-------
Tensile properties of the HOPE FMLs were measured in accordance with
ASTM D638 at a jaw separation speed of 2 ipm using ASTM D638 Type IV dumb-
bells. Modulus of elasticity was measured in accordance with ASTM D882 using
1/2-in. wide strips at an initial jaw separation of 2 in. and a speed of
0.2 ipm (inches per minute), i.e. with an initial strain rate of 0.1 in.
in.~l min.'l, which is specified in the test method. Using specimens of
sufficient size to be tested with an initial jaw separation of 10.0 in. as
specified by ASTM D882, would have resulted in higher test values. The
smaller test specimen size was used because it was easier to handle in the
high temperature chamber. Tear resistance was measured in accordance with
ASTM D1004, which specifies a specimen size identical to Die C from ASTM
D624, at 2 ipm.
The results of the tests are presented in Table 4-14. The tensile and
elongation at yield, the modulus of elasticity, and the elongation at break
are presented graphically, as a function of temperature, in Figures 4-22 and
4-23.
The tensile strength at yield, tear resistance, and modulus of elas-
ticity values of all five HOPE FMLs decreased in a similar fashion as the
test temperature increased. The differences in thickness of the five FMLs
did not affect the rates of change with temperature. Of the properties
tested, the modulus of elasticity was affected the most, decreasing the most
with the temperature increase up to 60°C (140°F). At 80°C (176°F), the rates
of change appeared to decrease and to level off between 60° and 80°C (140°
and 176°F). The values would all approach zero as the temperature approaches
the respective melting points of the HOPE FMLs.
In the second study, 10 unreinforced thermoplastic FMLs were tested at
room temperature and at 60°C. These FMLs included:
Matrecon Nominal
Polymer FML number thickness, mil
CPE 142 30
145 30
154 27
CSPE 148 30
PVC 143 30
146 30
153 30
155 30
PVC-OR 144 30
150 30
Tensile testing was performed in accordance with ASTM D638 at a jaw separa-
tion rate of 20 ipm using a dumbbell specimen size that featured smaller tab
ends and a shorter overall length than the ASTM D638 Type IV specimen. Tear
resistance was measured in accordance with ASTM D1004 at 20 ipm.
4-63
-------
TABLE 4-14. PROPERTIES OF HOPE FMLS OF VARIOUS NOMINAL THICKNESSES AT DIFFERENT TEMPERATURES
Thickness
Property
Tensile at yield,
psi
Elongation at
yield, %
Tensile at break,
psi
Elongation at
break, %
Set after break, %
-P. Stress at 100%
^ elongation, psi
Stress at 200%
elongation, psi
Modulus of elas-
ticity, 104 psi
Tear resistance,
ppi
Direction
of test
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
30 mil,
23°C
2650
2875
20
10
4065
4225
760
755
660
650
2065
2005
2120
2065
8.01
8.97
790
795
40°C
2095
2305
20
18
4510
5080
930
945
825
840
1890
1675
1720
1720
5.80
5.92
675
655
No. 269a
60°C
1355
1575
24
22
3810
3985
1080
1035
935
915
1340
1250
1290
1225
3.05
3.18
555
540
80°Cb
1285
1175
c
28
...
...
...
1240
1130
1190
1050
2.17
2.60
...
60 mi 1 ,
23 °C
3045
3225
15
15
3405
2940
885
760
785
665
1945
1990
1950
1970
11.8
11.8
855
890
40 "C
2740
2835
17
16
3475
3270
1050
965
960
865
1835
1800
1825
1825
7.95
8.89
770
770
No. 185a
60°C
1855
1990
21
19
2540
2560
1240
1140
1150
1065
1360
1380
1260
1335
3.76
3.62
595
610
80°Cb
1505
1490
24
22
• • •
...
• • •
1185
1130
1165
1110
3.17
3.44
...
and test temperature
70 mil,
23 °C
2675
2690
20
20
4365
4285
815
785
690
695
1875
1880
1875
1880
9.89
9.57
785
780
40°C
2170
2160
19
18
4235
4285
965
890
855
790
1625
1565
1620
1570
5.40
6.16
685
680
No. 266a
60°C
1355
1325
21
20
3620
3635
1110
1075
975
910
1180
1205
1175
1150
3.04
3.13
565
540
80°Cb
1175
1185
25
24
...
...
• . .
1140
1115
1080
1105
2.68
2.36
...
90 mil,
23 °C
3080
3175
18
18
3920
3845
845
815
750
720
1995
2080
1995
2050
11.2
10.9
900
895
40°C
2445
2435
19
20
3865
3765
955
950
855
840
1695
1645
1675
1645
6.34
5.58
765
750
No. 262a
60°C
1580
1630
18
19
3195
3275
1160
1145
1030
1035
1220
1270
1205
1260
4.15
3.30
610
600
80°Cb
1550
1510
23
24
...
...
...
1260
1185
1225
1180
3.04
2.43
...
100 mil
23 °C
2705
2700
17
15
3530
4065
785
860
680
750
1930
1945
1930
1940
8.69
8.20
900
885
40 °C
2270
2235
18
17
3465
3905
930
1045
800
925
1665
1645
1660
1635
5.74
5.91
765
755
, No.
60 °C
1625
1660
19
21
2625
2660
1170
1235
1035
1095
1290
1285
1260
1275
3.34
3.09
615
605
288a
80°Cb
1290
1245
19
21
...
• • *
...
1095
1105
1080
1085
3.20
2.90
...
aMatrecon liner number.
bSpecimens tested at 80°C were extended only to 200% elongation due to the limited size of the temperature chamber which prevented the specimens from
being extended all the way to break.
cExact point of yield difficult to determine because stress-strain curve revealed a plateau and not a peak.
-------
._ 4000
in
a
3000
UJ
H
< 2000
UJ
i/i
2 100°
OP
%
a
UJ
H
H-
O
0
36
35
30
25
20
15
10
5
0
HOPE 269
30 mil
T
T~
_L
_L
_L
HOPE 185
60 mil
—r
T
J L
HOPE 266
70 mil
r
HOPE 262
90 mil
1 T
_L
J_
20
-------
120x10'
V)
a
* 100x103
O
I-
t/1
UJ
a
o
80x10-
60x10-
10x1 O
20x1 O
ui
a:
CO
z
o
(-
o
z
o
at
600
HOPE 269
30 mil
HOPE 185
60 mil
HOPE 266
70 mil
HOPE 262
90 mil
HOPE 288
100 mil
-L.
_L
_L
0 20 40 60 80 0 20 "»0 60 80 0 20 10 60 80 0 20
TEST TEMPERATURE, °C
_l_
"I T
_L
J_
60 80 0 20 "tO 60 80 100
Figure 4-23. Modulus of elasticity and elongation at break of five HOPE
FMLs of 30 to 100 mil thickness tested at 23° to 80°C (73° to
176°F).
The elongation at break of these FMLs were substantially higher at 60°C
(140°F) than they were at room temperature. With the exception of the CPE
FMLs, which showed approximately 200% retention of the values for elongation
at break at 23°C (73°F), the elongation at break retention values for the
thermoplastics were similar to the retention values for the HOPE FMLs, i.e.
in the order of 140-150%.
Effect of Rate of Deformation on Puncture Resistance. Maintaining the
integrity of an FML during installation and in service is essential for the
proper functioning of a liner. During installation the FML can be punctured
4-66
-------
TABLE 4-15. PROPERTIES OF THERMOPLASTIC FMLS AT DIFFERENT TEMPERATURES
-p*
--J
CPE
27 mil, 30 mil,
Direction No. 154» No. 142«
Property
Tensile at break,
psi
Elongation at
break, I
Set after
break, t
Stress at 100%
elongation, psi
Stress at 200%
elongation, psi
Tear resistance,
ppi
of test 23°C
Machine 2395
Transverse 2200
Machine 440
Transverse 485
Machine 220
Transverse 200
Machine 905
Transverse 605
Machine 1240
Transverse 875
Machine 230
Transverse 215
60°C 23°C 60°C
b.c 2165 285C
b,c 1990 l>,c
>900*> 350 800
>900b 470 >900b
b 125 215
b 120 b
305 1040 305
210 465 140
350 1445 340
205 710 130
130 190 130
100 195 80
30 mi 1 ,
No. 145»
23°C 60°C
2350 315C
2250 b,c
410 835
515 >900b
215 285
190 ...
1340 365
670 190
1620 380
990 170
245 150
230 115
CSPE
PVC
30 mi 1 , 30 mi 1 , 30 mi 1 , 30 mi 1 ,
No. 148* No. 143a No. 146a No. 153«
23°C 60°C 23°C
1275 335C 2865
1210 190 2620
360 410 340
585 900 360
135 55 95
250 200 110
1120 360 1470
620 150 1315
1240 355 2065
745 165 1820
295 115 370
255 100 335
60°C 23°C
1770 3240
1585 2990
510 320
550 360
115 75
135 95
540 1680
470 1490
815 2405
675 2080
195 380
205 350
60°C 23°C 60°C
1980 2765 1740
1980 274 1980
440 290 410
585 350 510
90 65 70
135 105 115
660 1600 665
500 2410 570
1040 1800 735
755 1560 570
235 325 175
225 275 170
PVC-OR
34 mil,
No. 155a
23°C 60°C
2860 1835
2540 1740
315 460
335 515
75 95
80 120
1495 585
1315 520
2250 1055
1965 870
375 205
345 205
30
No.
23°C
2655
2275
365
355
75
70
1235
1085
2120
1835
345
345
mil.
144«
60°C
1625
1340
490
550
105
115
480
385
915
735
190
190
30-mi 1 ,
No. 1503
23 °C
3425
3090
275
395
30
75
2110
1515
2975
2080
420
350
60 °C
1905
2110
365
540
50
145
885
540
1405
840
220
205
aMatrecon liner number.
bThe limited size
cln the process of
strength occurred
of the elevated-temperature chamber prevented the
test specimens from
being stretched all the way
being extended at 60°C, the thermoplastic CPE and CSPE FMLs underwent plastic flow and thinning.
before break. Maximum tensile strength values and the recorded elongation values at the maximum
Maximum
tensile strength, psi
CPE (154)
CPE (142)
CPE (145)
CSPE (148)
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
440
>245
420
195
390
145
360
Elongation
maximum tensile
ca 400
>900
ca 400
ca 100
ca 425
<100
ca 125
to break.
Consequently,
tensile values
at
strength, %
maximum tensile
are as follows:
Note: CPE Liner No. 154 went through a maximum at approximately 100% elongation.
-------
by the accidental dropping of tools, by machinery, or by other equipment.
Once a hole is made, it is difficult to detect as the FML is often black and
may be soiled during installation. Puncturing may also take place during
placement of a soil cover on the FML because of falling rocks and other sharp
objects and, once the FML is covered, the holes are not visible. Once in
service, the FML may be penetrated or punctured slowly from the load placed
on the FML or from hydraulic pressure when the FML bridges a small cavity.
Uncovered FMLs may be subjected to traffic damage and possibly to damage by
animals, such as from deer hooves, rodent burrows, and birds. Consequently,
high resistance to puncture is an important property of FMLs, especially
because of the difficulties involved in detecting holes and repairing in-
place liners.
Since FMLs are viscoelastic, the rate of deformation can have a signi-
ficant effect on the force required to puncture them. The effect of the rate
of deformation on puncture resistance test results was studied by Matrecon.
Testing was performed in accordance with FTMS 101C, Method 2065, which is
described in Section 4.2.2.5.2. In this procedure, a 0.5-in. diameter probe
with one end tapered to a 0.125-in. radius penetrates a 2-in.-sq test speci-
men that is confined between two plates through which a 1-in. diameter hole
has been drilled.
Figure 4-24 presents the results of testing both an unreinforced thermo-
plastic FML (30-mil PVC 137) and an unreinforced crosslinked FML (45-mil EPDM
166) at 0.2, 0.5, 1.0, 2.0, and 20 ipm. The range of the test results at
each speed of deformation is indicated by the use of bars. These results
show that a slower rate of puncture will result in a slightly lower puncture
resistance value for these types of FMLs.
Because of the known susceptibility of semi crystalline materials to
test speed, two different HOPE FMLs produced by the same manufacturer at 0.2,
0.5, 1.0, 2.0, 5.0, and 20 ipm were also tested. One was 35 mils in thick-
ness, and the second was 85 mils in thickness. These results are presented
in Figure 4-25. The range of test results for each speed of test is indi-
cated by the use of bars. The results show a somewhat greater susceptibility
to speed in comparison with the results of testing the crosslinked and
thermo-plastic sheetings, particularly with the thicker sheeting. It should
be noted that the values reported for puncture testing are absolute values
and no corrections for variations in thickness are made. Some of the vari-
ability in test results is caused by variations in the thickness of the
tested specimen.
The results of this testing indicate that:
- The rate of deformation affects the amount of force required to
puncture an FML.
- The crosslinked, the thermoplastic, and the semi crystalline FMLs
tested had a log-linear relationship between rate of test and maximum
force. The slope of this relationship was dependent on both the
thickness and the composition of the FML.
4-68
-------
fi
s"
I
I
Is
100
80
60
40
20
1 r
1 r
Unreinforcad 30-mil PVC FML 137-
Unreinforced 45-mil EPDM FML 166 -
_L
_L
_L
0-1 0.2 0.5 1.0 2.0 5.0
Speed of Deformation, ipm
10
20
40
Figure 4-24.
Force at puncture (FTMS 101C, Method 2065) vs speed of deform-
ation of two.unreinforced FMLs.
160
140
120
100
80
60
40
20
80-mil HOPE - FML P467
40-milHDPE-FMLP419
0.1 02 0.5 1.0
20
so
Speed of Deformation, ipm
Figure 4-25.
Force at puncture (FTMS 101C, Method 2065) vs speed of defor-
mation for two different thicknesses of HOPE FML produced by
the same manufacturer.
4-69
-------
Effect of Thickness on Puncture Resistance. Another important variable
affects the puncture resistance of an FML is its thickness. This
was investigated by determining the puncture resistance of a series
FMLs of different thicknesses that had been produced by the same
These thicknesses ranged from 22 to 112 mils. The results are
Figure 4-26, which shows an almost linear relationship between
that
variable
of HOPE
manufacturer.
presented in
force at puncture
and thickness.
160
140
120
100
80
60
40
20
20
40
60
80
100
120
140
Thickness, mil
Figure 4-26.
Force at puncture (FTMS 101C, Method 2065) vs thickness of test
specimen for six different HOPE FMLs produced by the same
manufacturer.
Effect of Lubrication on Puncture Resistance.
FMLs in service are
normally damp or wet on both surfaces, under which condition they are more
likely to be punctured. Two studies of the effect of lubricating the probe
used to puncture test specimens on puncture resistance, as measured in
accordance with FTMS 101C, Method 2065, were performed by Matrecon. In the
first study, two HOPE FMLs (Nos. 358 and 359) were tested. These FMLs were
produced by different manufacturers and were of different thicknesses. The
probe was lubricated with either SAE 30 oil or castor oil. The results of
testing these FMLs with and without lubrication are compared in Table 4-16.
The lubrication caused a 6-8% loss of maximum force, which in the case of
these FMLs was the force at yield. Lubrication probably did not affect
deformation at the initial yield. The force and deformation at puncture
values showed somewhat more significant losses.
4-70
-------
In the second study, the combined effect of lubrication and speed of
test were investigated. A 40-mil FML (HOPE 419) was tested at two different
speeds, 2 and 20 ipm, with the probe lubricated with either glycerine, castor
oil, or SAE 30 oil. The results are presented in Table 4-17. As in the
previous study, lubrication caused losses in maximum force and in force
and deformation at puncture. In addition, deformation at initial yield
appeared to be affected. Lubrication had more of an effect on the 20 ipm
testing than the 2 ipm testing, as can be seen in Figure 4-27.
TABLE 4-16. THE EFFECT OF LUBRICATING THE TIP OF THE PROBE WITH SAE
30 OIL AND CASTOR OIL ON THE PUNCTURE RESISTANCEa OF TWO HDPE FMLS
FML number
358
359
Castor
Measurement
Thickness, mil
Maximum forceb, lb
None
89.
141.
3
0
SAE
89
133
30
.4
.2
oi
89
129
1
.6
.2
None
102.2
170.2
SAE
101
157
30
.5
.7
Castor
oil
101
157
.8
.4
Deformation at
maximum force, in. 0.28
Force at puncture, lb 129.2
Deformation at puncture,
in. 0.62
0.27 0.27
106.4 96.1
0.56 0.54
0.28 0.27 0.26
139.3 113.2 104.6
0.60 0.52 0.51
aMeasured in accordance with FTMS 101C, Method 2065.
averages for five test specimens.
bMaximum force occurred at initial yield.
All results are
Multiaxial Strain-Stress Behavior of FMLs. Tensile and tear property
testing are often performed as if they can give some indication of the
strength of an FML in the field where it is subjected to stresses in three
dimensions. Data on tensile and tear properties that are usually reported
and used in specifications for FMLs are obtained in tests run in only one
direction at a time. If there is a grain introduced during manufacture, the
FML is tested in both the machine and transverse directions. This type of
test is satisfactory for amorphous thermoplastic materials. However, the
stress-strain behavior of semi crystal line FMLs or FMLs which crystallize
on stretching when deformed simultaneously in two or three directions is very
different from the stress-strain behavior of these materials when deformed in
only one direction.
To assess multiaxial tensile properties of FMLs, Steffen (1984) con-
structed the testing device shown in Figure 4-28. This device, which is a
4-71
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80
60
£
s
(X
TO
0}
O
40
20
Q-
D—— ••"—~"""
o Unlubricated Probe
A Probe Lubricated with Glycerine
D Probe Lubricated with Caster Oil
• Probe Lubricated with SAE 30
0.2
0.5
1.0
2.0
5.0
20
50
Speed of Deformation, ipm
Figure 4-27.
Effect of lubricating the probe on puncture resistance of
40-mil HOPE FML (No. 419) at different speeds of deformation.
Puncture resistance measured in accordance with FTMS 101C,
Method 2065.
Window
Window
Figure 4-28.
Pressure vessel device for three-dimensional stress-strain
tests; diameter of vessel is 1 m. (Based on Steffen, 1984,
p 181).
4-72
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TABLE 4-17. COMBINED EFFECTS OF LUBRICATION OF THE PROBE AND THE SPEED
OF DEFORMATION ON THE PUNCTURE RESISTANCEa OF A 40-MIL PE FML (NO. 419)
Test speed, ipm
20
Measurement
Glyc- Castor Glyc- Castor
None erine oil SAE 50 None erine oil SAE 50
Thickness, mil
Maximum force,
Ib
Deformation at
initial yield,
in.
Force at
puncture, Ib
Deformation at
puncture, in.
34.8 34.8 35.3 36.0 35.7 36.0 36.3 35.8
52.lb 47.4C 43.4d 46.Od 59.5b 48.3d 47.Od 46.ld
0.29 0.24 0.23 0.24 0.27 0.23 0.23 0.24
47.5 47.4 35.1 40.5 54.9 43.9 37.9 42.1
0.72 0.63 0.44 0.52 0.78 0.54 0.45 0.53
aMeasured in accordance with FTMS 101C, Method 2065. All results are
averages.
bMaximum force occurred at secondary yield, i.e. when a second area which
was being deformed by the probe began to yield.
cMaximum force occurred at puncture.
dMaximum force occurred at initial yield.
1 m diameter pressure vessel, can perform bursting tests on circular speci-
mens 1 m in diameter which may or may not include a seam. The FML specimen
is fixed in the pressure vessel between the lower and the middle section.
The specimen is loaded with pressure from the upper side, and deformation of
the specimen and pressure are measured. It was found that the deformation
line approximates the form of a section of a ball. The strain and stress
for the different stages of the tests are calculated. Normally the test is
continued up to the bursting point.
Figure 4-29 presents the results of testing 9 different FMLs. The
thicknesses of the FMLs are included in the figure so that the stress values
for these materials can be corrected for thickness. The materials tested
included two HOPE FMLs, one PVC, one EPDM, two rubber-modified bitumens [i.e.
one standard ethylene copolymer with bitumen (ECB) material and one modified
ECB], a bituminous FML reinforced with both a net and polyester film (BIT),
and one butyl (IIR) FML.
4-73
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400
300
o
Z
o 200
100
ECB (2.0)
IIP (2.0)
10 20
30 40 50
Strain,%
60 70 80
Figure 4-29. Results of three-dimensional stress-strain testing of nine
FMLs. Numbers in parentheses indicate FML thickness in mm.
(Based on Steffen, 1984, p 182).
The results presented in Figure 4-29 show that the two PE FMLs failed
at a strain of 9 and 15%, respectively. Note: Some reviewers indicated that
these values are abnormally low for HOPE. These strain results are ap-
proximately 1 to 2% of the strain at breaks that are usually obtained in
uniaxial stress-strain tests and approximately 50% of the strain at the
tensile yield point results. These results differ greatly from the strain at
break values reported by manufacturers of HOPE FMLs. These low values for
strain at failure resulting from multiaxial testing seem to be at least one
of the reasons for failure of some HOPE FMLs in practice. However, the
differences between the breaking loads in uniaxial tests and in triaxial
tests are not so great.
FMLs that did not contain any crystallinity failed at a lower load and
at a higher strain than the HOPE FMLs. For these materials, the difference
between the strain at failure in uniaxial testing and those in triaxial test-
ing is not as large. The strain values in the triaxial tests are approxi-
mately 10% of those in the uniaxial tests.
Failure of the HOPE FMLs occurred in a small _
elongation in this area or with a spontaneous break
area either after a high
The FMLs without any
4-74
-------
crystal Unity usually failed after a high elongation in wide areas of the
test specimen. To find the correlation between the thickness of an FML and
the strain at failure, tests were made of three different thicknesses of HOPE
FMLs, all of which were of the same composition. Thicknesses ranged from 1.6
mm to 2.7 mm (63 to 106 mils). The results are shown in Figure 4-30. The
1.68-mm FML has a strain at failure of 7.4%, the 2.10-mm FML a strain at
failure of 10.2%, and the 2.70-mm FML a strain at failure of 12.4%. These
results show that the thickness of an HOPE FML affects how much it can deform
without failure.
re
(A
m
1.0
0.5
*
4
<9
• Bursting Pressure
o Average Extension
1.5 2.0 2.5
Thickness of FML, mm
3.0
Figure 4-30.
Relationship between thickness of FML and pressure and strain
at failure for three different FMLs of the same composition.
(Based on Steffen, 1984, p 183).
4.2.2.4.3 Chemical properties—The resistance of an FML to various
chemicals determines how the FML will interact with a waste liquid. Most
FMLs will absorb constituents of waste liquids and swell during exposure to
liquids containing organics, though some shrink; for example, highly plas-
ticized FML compositions, such as PVC FMLs, can lose plasticizer and other
components and shrink. These two processes can take place simultaneously
so that, in the case of plasticized compositions, the plasticizer can be
extracted and, simultaneously, the organic constituents in a waste liquid can
be absorbed and result in either a net swelling or loss.
Absorption of water and organics in the waste liquid by an FML and the
resultant swelling can cause deterioration of many physical properties. When
the physical properties of an FML have deteriorated on exposure to a waste
liquid, it is likely that there has also been swelling. However, physical
properties of FMLs other than tensile strength, elongation at break, tear
resistance, puncture resistance, and permeability can be affected by organics
and waste liquids without showing much swelling. Of particular importance
are the effects on semicrystalline FMLs which can, under simultaneous ex-
posure to waste liquids and mechanical stress, be subject to environmental
stress-cracking (ESC) and rupture. This type of failure can be minimized by
controlling molecular weight (MW) and MW distribution.
4-75
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The chemical properties of an FML that affect the magnitude of its
swelling in a liquid include the following:
- Solubility parameters of the polymer with respect to those of con-
stituents of the liquid.
- Crosslinking of the polymer.
- Crystal 1inity content of the polymer.
- Filler content of the compound.
- Plasticizer content of the compound.
- Soluble constituents in the compound.
- Molecular weight and MW distribution.
Due to differences in polymers and in compounding, some of these properties
do not apply or are not important for every FML.
For rubber and noncrystalline or amorphous polymers, the solubility
parameters are probably the most important factor in swelling and are used
by polymer scientists to measure the compatibility of an amorphous polymeric
composition with a liquid with which it may be in contact.
Crosslinking of a noncrystalline polymer or a rubber reduces its ability
to swell in a liquid which has solubility parameters similar to those of the
polymer. The amount of swelling of a crosslinked polymer in a good solvent
for the raw polymer can be used as a measure of the degree of crosslinking:
the greater the crosslinking, the less the swelling.
Crystallinity of a polymer acts much like crosslinking to reduce the
ability of a polymer to dissolve. The crystalline domains of most polymers
do not readily absorb organics at normal ambient temperatures. Highly
crystalline polymers, such as HOPE, will swell slightly in gasoline but will
not dissolve, even though they are both hydrocarbons.
Two additional factors in FML compositions that also can affect the
magnitude of swelling of noncrystalline polymers are the amount of particu-
late filler used in the compound recipe, e.g. carbon black, silica, or clay,
and the amount of plasticizer. As with the crystalline domains in semi-
crystalline polymers, nonporous particulate fillers such as those listed
do not absorb organics. In the case of plasticizers, they are generally
extractable by organic solvents, and most are only slightly extractable by
water.
Rubber and plastic compounds may contain minor amounts of water-soluble
inorganic salts which enter the compound via the polymer itself, e.g. cata-
lyst traces, salt used in flocculation, etc., and via small amounts in the
various compounding ingredients, e.g. many of the non-black fillers contain
4-76
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small amounts of water-soluble constituents. These water-soluble salts can
cause swelling by diffusion of water into the mass by the driving force of
osmosis.
Solubility parameters have found wide use in determining the solubility
of polymeric materials in various organics. Some of the many applications
are reviewed by Barton (1975). Also of particular interest are the uses of
these parameters in studying the plasticization of polymers, in preparing
rubber blends, and in designing rubber and plastic compositions for contact
with various oils, hydraulic fluids, and gasoline (Beerbower et al , 1963 and
1967).
The Hildebrand solubility parameter ( 60) and cohesive energy density
(CED) are concepts related by the following equation (Hildebrand and Scott,
1950, p 56):
«o = (CED)V2 = (AE/Vm)l/2 , (4-3)
where
AE = the energy required to vaporize one mole of material, and
Vm = the molar volume.
Thus, 60 is a measure of the potential energy of any material with respect
to its energy in an entirely disassociated form and is free of any intermole-
cular interactions. Intuitively, two different organics of exactly equal
potential energies should be mutually miscible in all proportions with no
loss or gain of energy. This model of solubility, termed the solubility
parameter model, was developed by Hildebrand (Hildebrand and Scott, 1950,
p 119) and may be expressed by the equation:
AEmix = Xi X2 («i - 62)2 . (4-4)
where
AEmjx = the energy of mixing,
xl,2 = tne volume fractions of components 1 and 2, and
<$1 2 = the solubility parameters of components 1 and 2.
Clearly, the mathematical model agrees with intuition in concluding that
equal solubility parameters imply no energy change on mixing.
The potential energy of organics may be simply expressed as 6 , but is
in fact a sum of energies due to several different types of molecular inter-
action. These include dipole-dipole interactions, London dispersion forces,
4-77
-------
hydrogen-bonding effects, and at very close distances, repulsive effects.
These energies are approximately additive (Hildebrand and Scott, 1950, p 56;
Garden and Teas, 1976, p 428; Hansen, 1967, p 104):
Etotal = E! + E2 + E2 + . . .
From the relationship betweeen 6and AE, it follows that:
6otal =
4
(4-5)
(4-6)
Consideration of the individual contributions of the solubility parameter
components becomes quite important in determining the solubility of complex
systems such as polymers. These do not behave in the "ideal" manner assumed
in construction of the solubility parameter model and consequently solubility
is sensitive to variations in the component solubility parameters, not just
the overall solubility parameters.
In order to properly describe the solubility of polymers, models more
complex than Hildebrand's solubility parameter model are required. The most
important model of this general form was proposed by Hansen (1967) and is
termed the three-dimensional solubility parameter model. It is written as:
6fotal =6d + 6 +*h (4-7)
where
^total = total Hansen solubility parameter,
64 = the contribution to the total solubility parameter due to
intermolecular London dispersion forces,
<5p = the contribution due to intermolecular dipole inter-
actions, and
<$n = the contribution due to intermolecular hydrogen-bonding.
Approaches taken by various researchers are described in Beerbower et al
(1963), Garden and Teas (1976), and Van Krevelen and Hoftyzer (1976).
Comprehensive tabulations of solubility parameters for common solvents and
other organic chemicals have been made by Barton (1975 and 1983). A general-
ly useful model will probably require parameters defining polymer crosslink-
ing and crystal linity as well as polymer solubility parameters, and may well
not be amenable to a simple graphic presentation.
To determine the solubility parameters of FMLs and the effect of various
chemical properties on swelling, Haxo et al (1987b) determined equilibrium
swelling of 28 FML-related polymeric compositions in 30 organics and DI
4-78
-------
water. These 28 polymeric materials included thermoplastic, crosslinked, and
semi crystalline compositions, of which 22 were commercial FMLs or sheetings
and six were laboratory-prepared compositions. Within these 28 compositions,
basic polymer and compound variations (such as polymer types, level of
crystal 1inity, crosslink density, filler level, and amount and type of
plasticizer) were included.
The 30 organics covered a wide range of Hildebrand solubility parameters
as well as the component solubility parameters, i.e. the dispersive (5
-------
TABLE 4-18. SOLUBILITY PARAMETER VALUES FOR FMLS AND
OTHER POLYMERIC COMPOSITIONS*
Matrecon
Polymer
Chlorinated polyethylene
Chlorosulfonated polyethylene
Epichlorohydrin rubber
Ethyl ene propylene rubber
Ethyl ene vinyl acetate
Neoprene
Nitrile rubber
Polyester elastomer
Polybutylene
Polyethylene:
Low-density
Linear low-density
High-density
HDPE/EPDM-alloy
Polyurethane
Polyvinyl chloride
Elasticized polyvinyl chloride
number «0
195
335R
378R
169R
174R
DOY-36
DOZ-26
DPOe
DPpe
178
232
308A
168
DPNe
316
323
221A
309A
284
184
263
305
181
351
153
DPQe
176R
Polyvinyl chloride (oil-resistant) 144
aMore data for these FMLs are
presented in
9.27
9.39
8.91
9.52
9.39
9.39
9.27
9.39
9.39
11.35
11.35
8.91
9.39
9.52
10.49
10.61
11.35
7.69
7.81
8.17
7.44
7.93
7.56
7.69
' 11.59
10.13
9.64
9.76
9.64
Appendix F.
«d
7.99
9.23
9.23
9.13
8.91
9.07
9.18
9.13
9.13
9.23
9.23
9.07
8.96
9.29
9.02
8.91
8.91
7.49
9.45
9.02
9.29
8.05
8.50
9.07
8.86
7.99
7.83
9.34
7.88
(cal/cm3)l/2
6p
3.23
2.06
2.84
0.93
1.76
1.03
1.91
1.91
1.96
5.00
5.54
0.64
0.88
1.72
2.50
2.06
4.02
0.05
0.05
0.05
0.05
0.05
0.05
0.15
3.82
5.39
5.64
4.26
4.41
«h
3.15
2.50
3.15
2.60
1.52
1.19
1.38
0.53
1.09
4.56
4.56
0.65
0.98
1.95
3.58
5.32
4.12
0.43
0.11
0.43
0.65
0.98
0.54
0.76
5.64
3.91
4.34
3.47
4.23
6t°
9.18
9.78
10.2
9.54
9.21
9.21
9.48
9.34
9.40
11.45
11.69
9.12
9.06
9.65
10.02
10.58
10.61
7.50
9.45
9.03
9.31
8.11
8.52
9.10
11.18
10.40
10.58
10.84
9.97
Ad
-0.09
+0.39
+1.29
-0.02
-0.18
-0.18
+0.21
-0.05
+0.01
+0.10
+0.34
+0.21
-0.33
+0.13
-0.47
-0.03
-0.74
-0.18
+1.64
+0.86
+1.87
+0.18
+0.96
+1.41
-1.63
+0.27
+0.94
+1.09
+0.33
60 = Hildebrand solubility parameter.
C6t = total Hansen solubility
parameter = \
/6d + 6l + 6
h '
<*A = fit - 6o-
laboratory-prepared compound (see Appendix F, Tables F-ll and
Source: Haxo et al, 1987b, p 41.
F-12).
4-80
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4.2.2.4.4 Durability—Polymeric FMLs used to line hazardous waste
storage and disposal facilities must be durable and maintain their integrity
and performance characteristics over the designed life of the specific
facility. Since the principal function of an FML is to prevent leakage and
migration of the wastes and their constituents, low permeability to the
contained materials must be maintained throughout the service life of the
FML. Also, resistance to physical damage and the integrity of the seams must
be maintained so that breaks, tears, and other holes in the liner system do
not develop. Durability is important even during installation so that an
effective barrier to waste migration can be achieved.
Ultimately, the service life of a given FML will depend on the intrinsic
durability of the material and on the conditions under which it is exposed
during service. Differences in composition and construction will cause FMLs
to vary in their response to the exposure conditions which, even within a
given facility, can differ greatly.
This subsection describes the ways in which polymeric compositions in
FMLs can degrade, and the environmental factors that can cause degradation in
these materials. These environmental factors are discussed in more detail in
Chapter 5 by the specific type of impoundment. This subsection also briefly
discusses ways of testing durability.
Intrinsic Durability of Polymeric FMLs. The intrinsic durability of an
FML depends on the polymer, the auxiliary compounding ingredients, and the
construction and manufacture of the sheeting.
All materials of construction are prone to deteriorate in service in
some way and eventually become unserviceable. The mode of deterioration
varies with the individual material and with the environment in which the
material is exposed. The deterioration of polymeric compositions becomes
apparent in one or more of the following ways:
- Softening and loss of physical properties due to polymer degrad-
ation by depolymerization and molecular scission. Some polymers
can gel and crosslink to yield brittle materials.
- Stiffening, and embrittlement due to loss of plasticizer and other
auxiliary ingredients.
- Loss of physical properties and increase in permeability due to
swelling which, in the extreme case, results in dissolution.
- Failure of FML seams due to interaction with the waste liquids
and due to stress on the seams.
Table 4-19 outlines the various degradation processes that might occur with
FMLs in a service environment.
The principal agents aggressive to polymeric compositions are heat,
oxygen, light, ozone, moisture, atmospheric N02 and S02> solvents, low
temperatures, stress and strain, and enzymes and bacteria. All of these
4-81
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TABLE 4-19. POTENTIAL DEGRADATION PROCESSES IN POLYMERIC FMLS DURING SERVICE
Process
Effect on FMLs
In weather exposure9
Oxidation
Elevated temperature
Ozone
UV light
Loss of volatile plasticizer
High humidity
In waste exposure^
Swel1i ng
Dissolution (if solubility
parameter of waste
constituent equal that
of FML)
Extraction of plasticizer
Extraction of antidegradant
Mechanical stress
Interface of waste and weather
Biodegradation, particularly
if oxygen is present
Stiffening, chalking, and crazing,
causing losses in mechanical prop-
erties, e.g. tensile strength, elonga-
tion, tear; crosslinking and chain
scission
Reduces mechanical strength and ac-
celerates degradation, generally by
stiffening on prolonged exposure;
sometimes softens
Cracks at points of strain
Stiffens and cracks
Stiffens and can become brittle
Water absorption, leaching of
antidegradant resulting in greater
susceptibility to oxidation and UV
Softens and loses properties;
increases in permeability
Hole or general loss of barrier
function
May stiffen and lose elongation
Make more susceptible to degradation
Creep of liner; cracking and breaking
Combination of weather and waste
exposure often more severe than
either alone
Plasticizers, oils, and monomeric
organic molecules can be degraded
aLiner exposed on either a berm or a
^Liner is either buried, covered, or
Source: Haxo and Nelson, 1984b.
slope.
below the waste/weather interface area.
4-82
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agents can be operative in the exposure of FMLs in service. In most situ-
ations two or more of these agents act together.
FMLs rarely encounter the temperatures that would cause polymer de-
composition. Sometimes, however, the elevated temperatures involved in
weathering and possibly in handling the impoundment contents might cause
oxidative thermal degradation in the presence of oxygen.
Photodegradation is only encountered on weather-exposed surfaces.
Most polymers are susceptible to degradation on exposure to ultraviolet
light; however, the introduction of UV absorbers, such as carbon black and UV
stabilizers, can greatly reduce and essentially eliminate this effect for
extended periods of time.
Ozone can be particularly damaging and cause cracking in polymers
that have unsaturation in their main chains. Ozone-cracking can only occur
at points of strain of 15-25% or more. Of the polymers that have been used
in FMLs, only butyl rubber and neoprene have unsaturation in their main
chains and can crack due to ozone attack.
Polymeric compositions under constant or cyclic stress and strain
can fatigue, lose mechanical strength, and crack. Cracks and breaks can
occur in an FML under biaxial strain at significantly lower stress values
than those encountered in uniaxial tensile tests. As is characteristic
of all materials, polymers creep under stress, which can result in thinning
and puncturing or rupturing of an FML. Environmental stress-cracking, a type
of failure of some PEs, involves the cracking of a strained material in the
presence of aggressive chemicals or such chemicals as detergents, silicone
oils, petroleum oils, linseed oils, or organic acids (Howard, 1959).
Polymers are generally considered to be resistant to biodegradation,
although some types are known to degrade (Schnabel, 1981). Oils, plastic-
izers, and possibly other monomeric type ingredients in compounds, however,
are biodegradable in the presence of air and humidity. Their loss can
result in stiffening and embrittlement of some compounds.
Though the mechanism is primarily physical, the swelling of a polymeric
material by a solvent, including water, is considered a chemical attack on
the material. Polymeric materials can vary greatly in their interaction with
solvents. The solvents are absorbed without affecting the molecular weight
of the polymer. They generally extract plasticizers and other ingredients
that are soluble in the particular solvents. Also, it is possible that
solvents can dissolve some of the polymers.
Environmental Factors Affecting FMLs in Service. The environment
in which an FML must exist will ultimately determine its service life. Table
4-20 enumerates environmental factors that can affect the durability of
polymeric liners in service. These environmental factors are discussed in
detail in Chapter 5.
4-83
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TABLE 4-20. ENVIRONMENTAL FACTORS AFFECTING
DURABILITY AND SERVICE LIFE
Compatibility factors with waste liquids:
Chemical
Physical
Combination of chemical and physical
Weathering factors - geographic location:
Solar radiation
Temperature
Elevated
Depressed
Cycles and fluctuations
Water -- solid, liquid and vapor
Normal air constituents, e.g. oxygen and ozone
Freeze-thaw and wind
Stress factors:
Mechanical stress, sustained and periodic
Stress, random
Physical action of rain, hail, sleet, and snow
Physical action of wind
Movement due to other factors, e.g. settlement
Discontinuity at penetrations
Burden, hydraulic head
Use and operational factors:
Design of system, groundwork and installation
Operational practice
Biological factors
Source: Haxo and Nelson, 1984b.
Service Life and Durability Testing. At the present time information
exists on the outdoor exposure of polymeric materials (Strong, 1980) and
methodologies are being developed for durability testing of materials that
are exposed to weather, such as on the berms and slopes of uncovered impound-
ments and reservoirs. Rossiter and Mathey (1983) describe a methodology for
predicting the service life of single ply roofing materials which, in many
respects, may be applicable to FMLs exposed to the weather on berms and
4-84
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slopes. Durability testing of materials by immersion or intermittent im-
mersion in waste liquids for predicting service life, however, has not been
fully developed.
Laboratory tests that do exist for assessing the durability of FMLs
under different environmental conditions range from chemical analyses to
tests of mechanical properties (e.g. tensile properties, tear resistance,
puncture resistance, and impact resistance) after exposure to high and low
temperatures, to ozone while under strain, to UV light, and to stress and
strain for extended periods of time. Some of these tests are discussed
below in the subsection, "Testing and Evaluation of FMLs."
A chemical compatibility-type test, EPA Method 9090, in which samples of
lining materials are immersed has been developed (EPA, 1986). This test is
discussed in more detail in Chapter 5. In this test the retention of select-
ed properties are observed as a function of immersion time. This test,
however, does not indicate the effect of immersion under strain and other
mechanical stresses due to temperature cycling, soil settlement, etc.
Maximum changes in .properties that can take place without affecting
overall performance have not been established. Nevertheless, laboratory
testing of several properties can yield data indicative of durability.
For the development of realistic laboratory tests that can predict the
performance and durability of FMLs and components of liner systems in service
knowledge is needed regarding actual performance and durability of these
materials in service. Information with respect to the type of distresses and
failures that these materials encounter in service is necessary to develop
and select tests that correlate with service. However, comparatively little
information of this type has become available in the public domain. Much
dependence has been and is still being placed on the knowledge of the per-
formance of FMLs and other components in applications and under service
conditions that may be similar to those encountered in waste containment.
4.2.2.5 Testing and Laboratory Evaluation of FMLs—
Because of the wide range of compositions and differences in the con-
struction of polymeric FMLs, different groups of index tests have been
developed for different polymeric FMLs.
The methods used for testing a specific FML will depend on the type
of FML being tested. Because sheetings used as FMLs have been developed by
three different industries (rubber, plastics, and textile), there are three
groups of standard index test methods. Some methods used to test one type of
FML are inappropriate for other types; for example, using a dumbbell with a
1/4-in. restricted area, which is used to test rubber vulcanizates, is un-
satisfactory for measuring the tensile properties of fabric-reinforced FMLs.
From the point of view of testing, there are four types of polymeric FMLs:
- Thermoplastic or uncrosslinked polymeric FMLs (TP).
- Vulcanized or crosslinked elastomeric FMLs (XL).
4-85
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- Semi crystalline thermoplastic polymeric FMLs (CX).
- Fabric-reinforced FMLs manufactured with either crosslinked or
thermoplastic polymers.
The types of testing performed on an FML may depend on the reason for
the testing. Before an FML is selected and purchased, the designer and/or
site owner tests various FMLs to determine whether any meet the design
requirements of the facility. These tests include a determination of the
compatibility of the FMLs with the waste to be contained and assess their
potential performance in service. Sheeting may also be tested to charac-
terize or to "fingerprint" the material. The concept of fingerprinting is
discussed in more detail in the following subsection. Testing a polymeric
FML at the time of installation has three uses: (1) to assess the quality of
the specific sheeting being placed at a site, (2) to determine if it is the
same material that was prequalified during initial selection, and (3) to
provide a baseline for assessing the effects of exposure on the FML. Testing
samples during service can be performed to assess the performance or the
condition of the FML and the seams. Eventually, correlations may be de-
veloped between simulation tests and field performance to yield tests that
can effectively predict the field performance of an FML in a given situation.
During an exposure, a change in one property is usually accompanied
by changes in other properties. No single property of an FML, however, has
been correlated with the performance or failure of an FML in the field.
Thus, a group of test methods is necessary to evaluate and characterize FMLs,
especially in assessing the effects of exposure or service. These methods
can be categorized into five groups:
- Analyses to fingerprint and assess composition.
- Tests of physical properties, including information regarding con-
struction and dimensions of the membrane.
- Tests to assess permeability characteristics.
- Tests to determine properties in stress environments, including
accelerated aging tests, tests in specific exposures, and compati-
bility tests; these include tests that assess the durability of
FMLs under conditions that simulate actual field service.
- Performance tests to determine actual engineering properties of
an FML that are needed for designing a liner system.
These analyses and tests can include measurements of the following
properties:
- Analytical properties:
—Volatiles.
—Ash.
4-86
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--Extractables.
—Gas chromatography.
--Pyrolysis gas chromatography.
--Infrared spectroscopy.
—Specific gravity.
—Thermogravimetric analysis.
--Differential scanning calorimetry (if FML is semi crystalline).
--Melt index (if FML is semi crystalline).
--Molecular weight (average) and molecular weight distribution.
- Physical properties:
--Thickness.
--Tensile properties.
--Modulus of elasticity (if FML is semi crystal line).
—Hardness.
--Tear resistance.
--Puncture resistance.
--Hydrostatic resistance.
—Strength of factory and field-prepared seams.
- Permeability characteristics:
—Water vapor transmission (WVT).
—Solvent vapor transmission (SVT).
--Gas permeability.
--Pouch test.
- Tests that measure environmental and aging effects:
—Resistance to ozone-cracking.
--Resistance to environmental stress-cracking (if FML is semi-
crystalline).
4-87
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--Low-temperature properties.
--High-temperature properties.
--Air-oven aging.
—Dimensional stability.
--Water absorption.
—Liner-waste compatibility testing.
--Soil burial.
--Pouch test.
—Outdoor exposure:
--Exposure of test slabs.
—Bent loops.
--Exposure in tubs filled with a waste liquid.
--Accelerated outdoor weathering using concentrated natural
sunlight (ASTM Methods D4364 and G-90-EMMAQUA).
- Performance tests:
--In-soil stress-strain tests.
--In-soil creep tests.
—Shear strength between FMLs and soils.
--Anchorage or embedment depth of an FML.
--Puncture (hydrostatic) resistance.
Performance of these tests are the basis of a testing protocol that can
be used to characterize the properties of an FML and to assess the effects of
environmental exposure. The subsequent paragraphs discuss these tests and
how they can be used to evaluate polymeric FMLs. Selected properties of
unexposed polymeric FMLs are presented in Appendix F.
4.2.2.5.1 Analytical properties of polymeric FMLs--Tab1e 4-21 lists
appropriate or applicable test methods for determining the analytical
properties of FMLs. The results of determining the volatiles, extractables,
ash content, and specific gravity of a group of unexposed polymeric FMLs are
presented in Table 4-22.
4-88
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TABLE 4-21. APPROPRIATE OR APPLICABLE METHODS FOR TESTING ANALYTICAL
PROPERTIES OF POLYMERIC FMLS
i
00
ID
FML without fabric rei
Property
Volatiles
Extractables
Ash
Specific gravity
Thermal analysis:
Differential scanning
calorimetry (DSC)
Thermogravimetry (TGA)
Melt index
Thermoplastic
Appendix G
Appendix E
ASTM D297,
Section 34
ASTM D792,
Method A
na
yes
na
Crossl inked
Appendix G
Appendix E
ASTM D297,
Section 34
ASTM D297,
Section 15
na
yes
na
nforcement
Semi crystalline
Appendix G
Appendix E
ASTM D297,
Section 34
ASTM D792,
Method A
yes
yes
ASTM D1238
Fabric reinforced
Appendix G
(on selvage and rein-
forced sheeting)
Appendix E
(on selvage and rein-
forced sheeting)
ASTM D297, Section 34
(on selvage)
ASTM D792, Method A
(on selvage)
na
yes
na
na = Not applicable.
-------
TABLE 4-22. ANALYSIS OF UNEXPOSED POLYMERIC FMLSa» b
Property
Base polymer,
Polymer specific gravity0
Butyl rubber
Chlorinated
polyethylene
Chlorosulfonated
polyethylene
Elastic! zed
polyolefin
Epichlorohydrin
rubber
Ethyl ene propylene
rubber
Neoprene
Polybutylene
Polyester elastomer
Polyethylene
(low-density)
Polyethylene
(high-density)
Polyethylene (high-
density) alloy
Polyvinyl chloride
0.92
1.16-1.26
1.08
0.92
1.27-1.36
0.86
1.25
0.91
1.17-1.25
0.92
0.96
0.95
1.40
Specific Volatiles,
gravity %
1.206
1.176
1.360
1.362
1.377
1.433
1.343
0.938
1.490
1.173
1.122
1.199
1.503
1.480
1.390
0.915
1.236
0.921
0.961
0.949
1.275
1.264
1.231
1.280
1.308
0.45
0.46
0.10
0.00
0.05
0.84
0.51
0.15
0.63
0.38
0.50
0.31
0.76
0.19
0.37
0.12
0.26
0.18
0.12
0.11
0.11
0.09
0.05
0.31
0.03
Extract-
ables,
%
10.96
11.79
7.47
9.13
6.02
1.49
3.77
5.50
7.27
23.41
31.77
18.16
10.15
13.43
21.46
4.42
2.74
2.07
*0.60
2.09
33.90
37.25
38.91
35.86
25.17
Ash,
%
5.25
4.28
14.40
12.56
17.37
33.95
3.28
0.90
4.49
6.78
5.42
0.32
12.98
13.43
4.67
0.08
0.38
0.13
0.46
0.32
6.20
5.81
3.65
6.94
5.67
aSource of some of the data: Haxo et al, 1982.
bEach line of data represents the results of testing one liner sample.
Multiple lines of data for a specific polymer type represents the
results of analyzing samples from different manufacturers.
cBased on information supplied by the polymer manufacturers.
4-90
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Volatiles. The volatile fraction is defined as the weight lost by
an FML specimen on heating in a circulating air oven at 105°C for 2 hours.
Polymeric compositions generally contain a small amount of volatiles (<1.0%),
mostly absorbed moisture. A detailed description of the procedure for
determining volatiles is presented in Appendix G. The recommended test
specimen size is a 2-in. diameter disk.
Volatiles should be removed before determining ash, extractables, and
specific gravity. Ash and extractables are reported on a dry basis (db).
Volatiles contents of representative FMLs are presented in Table 4-22.
Monomeric plasticizers, which are generally used in PVC liner compositions,
are somewhat volatile and can slowly volatilize at 105°C. Thus, heating
specimens to 105°C in an air oven to determine volatiles content must
be limited to 2 hours to prevent plasticizer volatilization.
Determination of volatiles is generally the first test performed on an
exposed FML sample and needs to be run as soon as possible after the sample
has been removed from exposure. This test indicates the amount of volatile
constituents that has been absorbed by the FML during exposure. In cases
where it is not possible to measure the increase in weight of an exposed
sample directly, the weight increase can be approximated using the following
formula:
Vc
Weight increase, % = 1QQ _ y x 100% , (4-8)
where
VE = percent volatiles of the sample after exposure.
This formula assumes that the volatiles content of the unexposed FML was
equal to zero.
If the volatiles specimen from an exposed sample is to be used for
measuring specific gravity, care must be taken to avoid causing a "skin" to
form on the surface of the specimen, which is the result of trying to remove
the volatiles too quickly at too high a temperature. For example, in measur-
ing the volatiles of an exposed CPE FML, a disk specimen heated at 105°C
developed blisters that were caused by the surface sealing in the volatiles
in the center of the specimen. To prevent this from happening, specimens can
be taken up to temperature very gradually. A procedure that has been used
allows specimens to dehydrate for 1 week in moving air. The specimens are
then heated in a circulating air oven for 20 h at 50°C over a desiccant and
then for 2 h at 105°C. In the case of highly swollen samples, disk specimens
can also be allowed to come to constant weight at 50°C before being placed in
the 105°C oven. After the volatiles are removed, the exposed materials can
be subjected to other tests, including specific gravity, extractables,
ashing, etc.
4-91
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Inasmuch as the volatiles contain both water and organic components,
it may be desirable to distinguish between the two. The disk specimen can
be heated at 50°C for 4 days in a small, individual desiccator containing
calcium chloride to remove the moisture without removing the organic vola-
tiles. The organic volatiles can then be removed by heating the specimen
for 2 h at 105°C in a circulating air oven. The composition of the organic
volatiles can be determined by headspace gas chromatographic analysis of
vapors sampled from a sealed can in which a specimen has been heated.
Total volatiles can also be determined through the use of TGA which
is discussed in the paragraphs on TGA. The composition of the volatiles
can be determined by head space analysis, such as described under gas
chromatography.
The volatiles test can also be used to determine the direction of the
grain that has been introduced in an FML during manufacture. By identifying
the orientation of the specimen with respect to the sheeting at the time the
specimen was died out, the grain direction can be identified. The grain
direction must be known so that tensile and tear properties can be determined
in machine (grain) and transverse directions. Upon heating in the oven at
105°C, sheeting with a grain will shrink more in the grain direction than in
the transverse direction (Figure 4-31). With semicrystalline FMLs, such as
HOPE, which have higher softening or melting points, it may be necessary to
heat the disk to higher temperatures to observe the shrinkage.
As received After air-oven heating
2 h at 105°C
Figure 4-31. Determination of grain or machine direction.
Testing the volatility of plasticizers in
be performed in accordance with ASTM D1203. In
coal is used to absorb volatilized plasticizer
conditions.
PVC compositions can also
this test, activated char-
under a controlled set of
4-92
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Ash. The ash content of an FML is the inorganic fraction that remains
after a sample, from which the volatiles have been removed, is thoroughly
burned at 550±25°C in a muffle furnace. The ash consists of the inorganic
ingredients that have been used as fillers and components of the curative
system in the liner compound, and the ash residues from the polymer. Dif-
ferent FML manufacturers formulate their compounds differently, and the ash
content is part of the "fingerprint" of a polymeric FML compound. The
residue obtained by ashing can be retained for other analyses (such as trace
metals analyses) needed for further identification. The test method des-
cribed in ASTM D297 is generally followed in performing this analysis. Ash
contents of representative FMLs are presented in Table 4-22. Ash content can
also be determined by T6A.
The ash content of an exposed FML sample can differ from that of the
unexposed FML, depending on how many nonvolatile organics were lost or gained
during the exposure period. For example, if plasticizer is lost, the ash
content will increase because of the decrease in nonash content, i.e., the
plasticizer, in the dried specimen. Also, if any organic metal compounds
are absorbed by the FML, they will increase the ash content. A comparison of
the elemental analysis of the ash with that of the original FML will deter-
mine whether any absorption of metal species occurred during the exposure.
No such absorption, however, has been observed in work performed by Matrecon,
even though organic metals can be absorbed.
Extractables. The extractable content of a polymeric FML is the frac-
tion of the compound that can be extracted from a devolatilized sample of
the FML with a suitably selected solvent that neither decomposes nor dis-
solves the base polymer. Extractables consist of plasticizers, oils, or
other solvent-soluble constituents that impart or help maintain specific
properties, such as flexibility and processibility. Measuring the extract-
able content is important in fingerprinting an FML. The extract and the
extracted specimen obtained by this procedure can be used for further an-
alytical testing (e.g. gas chromatography, infrared spectroscopy, ash,
thermogravimetry, etc.) and fingerprinting of the FML. A detailed des-
cription of the procedure for determining extractables is presented in
Appendix E. This procedure generally follows ASTM D3421 and D297.
Extractables of exposed FMLs may differ from the original values because
of the loss of extractable components to the waste liquid and because of
absorption of nonvolatile organics, e.g. oils. For example, if the FML has
been in contact with wastes containing nonvolatile constituents, the extract-
ables recovered may be greater than the original values. The extracts can be
analyzed by gas chromatography and infrared analysis to study the nonvolatile
organics that were absorbed, thus indicating which constituents of the waste
are aggressive to the FML, because they are the constituents that were ab-
sorbed. Even though these constituents may show up in only minor amounts
in a waste analysis, they may be scavenged by an FML because of their
chemical characteristics, e.g. their solubility parameters.
Because of the differences between the polymers used in FML manufacture,
a variety of extracting media must be used. The solvents found to be the
4-93
-------
most suited for determining the extractables of FMLs of each polymer type are
listed in Appendix E. However, because FMLs can be based on polymeric alloys
marketed under a trade name or under the name of only one of the polymers,
this list has only served as a guideline for choosing a suitable solvent for
determining the extractables. When extractables determinations are being
used to assess the effects of exposure in an exposure study, and once a
suitable solvent has been found, it is important that the same solvent be
used for determining the extractables across the range of exposure periods.
Typical values for the extractables in FMLs are given in Table 4-22.
Gas Chromatography. Gas chromatography (GC) can be used to find the
level of a specific plasticizer that has been compounded into an FML, e.g.
the level of diethylhexyl phthalate (DEHP), a dioctyl phthalate (OOP), in a
PVC FML. Gas chromatography separates organic compounds from a mixture
based on their boiling points and polarities. A small sample of mixture
is injected into a gas chromatograph and the components of the mixture are
separated in a column through which an inert gas, such as helium or nitrogen,
is flowing. The compounds that are most volatile and least polar elute
first and are detected by ionization in a hydrogen/oxygen flame. Organic
compounds can be characterized by their retention time on the column at a
certain temperature. Thus, small amounts of a complex mixture can be tenta-
tively identified or compared to other mixtures based on similar retention
times. For positive identification, additional corroborative analysis, such
as mass spectrometry, would be necessary.
A typical gas chromatographic procedure for determining the type and
amount of plasticizer involves measuring the level of a plasticizer in
the redissolved extract from an FML. A weighed sample of FML is extracted
with an appropriate solvent. The extract is evaporated to dryness over a
steam bath to determine its weight. The dry residue is redissolved in
solvent and brought to an accurately known volume. Following the development
of appropriate chromatographic conditions, the solution is injected into the
gas chromatograph. Using predetermined retention times of specific plasti-
cizers, the unknown plasticizer constituents can be identified. Comparing
peak-height (or area-under-the-curve) data obtained from the injection of
equal volumes of the extract solution and quantitatively prepared standard
solutions of the identified plasticizer constituents allows the concentra-
tion of the identified plasticizer in the extract solution to be determined
by interpolation. Figure 4-32 shows the quantification of DEHP (about 0.7 g
L~l) in the solvent extract of a PVC FML. Assuming that the extraction was
100% efficient, the percent, by weight, of DEHP in the FML can then be
calculated.
GC can also be used by headspace analysis to analyze the volatile
organics absorbed by an FML during an exposure. In the headspace gas chro-
matography (HSGC) procedure, an exposed FML specimen is placed in a small
vapor-tight can provided with a septum through which vapors from the specimen
can be sampled. The can is placed in an oven at 105°C and heated for ap-
proximately one hour. A sample of the vapors is drawn from the can and
injected into the GC. The FML specimen is removed from the sample can and
4-94
-------
placed in a new can which is then heated in a 105°C oven for approximately
one hour. Once again, the vapors inside the can are sampled and injected
into the GC. The process of heating, sampling, and injecting is repeated
until no organics are detected in the sampled vapors by the GC. The conc-
entrations of the organics in the injected samples can be calculated by
comparing peak height values with calibration curves prepared by analyzing a
specific volume of vapor (e.g. 100 uL or 400 pL) from headspace cans injected
with different volumes of a standard solution of organics.
1.0
en 0.8
uT
X
Q.
X
LU
UJ
O
0.6
0.4
0.2
O Standards
-f Sample
34567
PEAK HEIGHT IN CM
10
11
Figure 4-32. Gas chromatographic determination of the diethylhexyl phthalate
content in an extract of a PVC FML. Column: 6 ft x 1/8 in., 3%
methyl silicone (0V 101) on Chromosorb WHP, mesh size 100-120.
Temperature: 200~300°C at 8°C/min. Helium carrier gas: at 30
mL/min.
Pyrolysis Gas Chromatography.
alternative method for measuring the
Pyrolysis gas Chromatography is an
plasticizer content of FMLs. In this
4-95
-------
technique, a small, weighed FML sample is heated very rapidly to a temper-
ature sufficient to volatilize all of its organic components. The plas-
ticizer and other lower-molecular weight organics will be driven off as
chemically unchanged vapors. The polymer will undergo pyrolysis, or high-
temperature decomposition, and will volatilize as lower-molecular-weight
organic compounds. The resulting volatiles can be separated and quantified
by gas chromatography as previously described, and the plasticizer content of
the liner can be calculated.
This method has the strong advantage of not requiring extraction of
the liner sample, but it may not be as reliable a means of quantification
because of the very small sample size and the large number of components
that must be separated by the gas chromatograph.
Infrared Spectroscopy. Infrared spectroscopy is the analysis of organic
molecules/mixtures by their absorbance of infrared radiation. Each molecule
contains a unique set of functional groups which absorb radiation at a
precise frequency. The intensity of radiation absorption at that frequency
by an individual molecule is dependent on the amount of that functional group
present in that particular molecule. Each molecule will have a unique
spectrum based on the combination of functional groups in the molecule. The
use of the IR spectrophotometer on FML extracts provides information on the
composition of an FML and can be used in fingerprinting. It can also be used
to indicate compositional changes in formulations of antioxidants and the
decomposition of antioxidants with time and exposure to environmental condi-
tions. An example of an infrared scan of the dried film from an n-hexane
extract of an unexposed HOPE FML is presented in Figure 4-33.
Although only a fraction of a percent of material was extracted from
the polyethylene, this example of an extract showed by the absorption at
1710 cm~l that the extracted solids consisted essentially of hydrocarbons
and small amounts of other ingredients, possibly esters or phenols which may
be associated with antioxidants. This type of curve functions primarily as a
fingerprint. Further analysis by other means would be needed to identify all
constituents. The IR curves of the extracts of exposed PE FMLs indicate
whether organics have been absorbed by the PE and give an indication of the
general character of the absorbed organics.
Specific Gravity. Specific gravity is an important characteristic of a
materialand is generally easy to determine. Determinations are often made
on devolatilized specimens. Because of differences in the specific gravities
of the base polymers, specific gravity of the FML compound can give an
indication of the composition and identification of the polymer. Specific
gravities of base polymers and of selected FMLs are presented in Table 4-22.
These results show the differences among polymers and the variations in
compounds from one manufacturer to another.
ASTM Method D792, Method A-l, and ASTM Method D297, Hydrostatic Method,
both of which are displacement methods, are generally used in determining
specific gravity. These two methods are essentially the same procedure.
4-96
-------
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-------
For example, when a material is heated in an inert atmosphere from room
temperature to 600°C at a controlled rate, it will volatilize at different
temperatures until only carbon black, char, and ash remain. The introduction
of oxygen into the system will burn off the char and carbon black. The
weight-time curve, which can be related to the weight of the sample remain-
ing and temperature, can be used to calculate the volatiles, plasticizer,
polymer, carbon black, and ash contents. In some cases, TGA can replace the
methods used to measure the volatiles, ash, and extractables contents dis-
cussed above. The TGA curve and the derivative of the TGA curve can thus be
used as part of a fingerprint of a polymeric composition. This technique is
described by Reich and Levi (1971), Turi (1981), Earnest (1984), and Matrecon
(1986).
In the work performed by Matrecon, a Perkin-Elmer TGS-2 thernogravi-
metric system, consisting of an analyzer unit, balance control unit, heater
control unit, and first derivative computer, was used. Temperature control
was supplied by the temperature controller on the Perkin-Elmer DSC-2 (Dif-
ferential Scanning Calorimeter). A double side-arm furnace tube was used to
allow rapid changing of the atmosphere from inert (N2) to oxidative (N2/02
mixture). For the oxidative atmosphere, ^-purity was maintained through
the analyzer unit head, and 03 was introduced at the upper side arm where
it mixed with the N£ to burn the carbon black and any carbonaceous residue
that forms during the pyrolysis of the polymer. Use of the double side-arm
furnace tube shortened the turnaround time because it eliminated the need
to flush the analyzer head completely to remove 02 between runs, as would
be necessary if 03 were introduced through the head. A dual pen recorder,
Perkin-Elmer Model 56 allowed a simultaneous display of thermocouple tempera-
ture in the furnace and the change in weight of the specimen or the first
derivative of the change in weight.
A TGA procedure followed by Matrecon for analyzing an FML is as follows:
a 5-mg specimen of the FML is placed in the balance pan and weighed in a
nitrogen flow of 40 mL/min. The instrument is adjusted to give a 100%
full-scale deflection for the weight of the sample so that the percent of
weight change can be read directly from the chart. The specimen is heated
to 110°C and held there for 5 min. to determine whether measurable volatiles
are present; the specimen is then heated from 110° to 650°C at a rate of
20°C/min. in a nitrogen atmosphere. The specimen is held at 650°C until no
additional weight loss has occurred, usually 2 to 3 minutes, after which it
is cooled to 500°C and 02 is introduced at a rate of 10 mL/min. with an
N2 flow rate of 30 mL/minute.
Typical thermograms for HOPE and EPDM FMLs appear in Figures 4-34 and
4-35, respectively. Analyses of a variety of polymeric FMLs are presented in
Table 4-23.
TGA can also be used to give a quick analysis of the composition of an
exposed FML. Testing an exposed FML follows the same procedure as testing an
unexposed FML, except that care must be taken in handling the small specimens
of exposed FMLs that contain volatiles. These volatiles can be easily lost.
4-98
-------
Figure 4-36 presents a thermogram of an exposed PVC FML which had in-
creased in weight by more than 7% due to absorption of the waste liquid
which was predominantly water. The thermogram shows four weight losses.
These weight losses are as follows:
- Weight loss A = 7.0% = volatiles = moisture + possible organics.
- Weight loss B = 60.2% = plasticizer + HC1 from the polymer (PVC).
- Weight loss C = 16.0% = residual polymer.
- Weight loss D = 10.0% = carbonaceous polymer residue.
1000
100
Volatiles 0
Oil 0
Polymer 95.5
Carbon Black 4.5
Ash 0
20 24 28
TIME, MINUTES
44
Figure 4-34.
TGA of an unexposed black HOPE FML. The plots of sample weight
and temperature as a function of time are shown. Under an N?
atmosphere, the black HOPE sample lost approximately 95.5% of
its mass as hydrocarbons were evolved. The carbon black added
as an UV light absorber remained as a carbonaceous residue and
was not volatilized until it was oxidized when oxygen was
allowed into the system.
4-99
-------
1000
Volatile;
Oil
Polymer
Carbon Black
Ash
24 28 32 36
TIME, MINUTES
56
60
Figure 4-35.
TGA of an tine/posed EPDM FML. The dotted line shows the
temperature program and the solid line shows the percent of the
original specimen weight. At 46 minutes the atmosphere was
changed from nitrogen to air to burn the carbon black.
The residue, E, which is the ash, is 6.8%. The losses show the effect
of the char formation of the PVC when it is heated in a nitrogen atmosphere.
Chlorinated polymers lose HC1 and leave a char which must be corrected for in
calculating the polymer content. The results of calculating the composition
of the exposed FML specimen in comparison with the results of direct analyses
of the same FML, are as follows:
Constituent
Volatiles, %
Polymer (PVC), %
Plasticizer, %
Carbon black, %
Ash, %
By TGA
7.0
52.1
34.1
~0
6.8
By direct analysis
7.9
• • •
32.2 (as extractablesi
• • •
6.4
The results obtained by TGA and those obtained by direct analysis are compar-
able. The differences in the results indicate that some of the volatiles may
have been lost in preparing the TGA specimen, that the extraction may not
have been 100% efficient, that a small amount of plasticizer may have been
driven off in the process of removing the extraction solvent from the ex-
tract, or that in devolatilizing the ash specimen, some of the plasticizer
may have been driven off. A large difference between the plasticizer content
4-100
-------
as determined by TGA and the extractables content as determined by direct
analysis would indicate that an unsuitable solvent was probably being used in
the extraction.
TABLE 4-23. THERMOGRAVIMETRIC ANALYSIS OF UNEXPOSED POLYMERIC FMLs
Polymer type
Volatiles, Polymer, Oil or plas- Carbon Ash,
% % ticizer, % black, % %
Butyl rubber
CPE
CSPE
ELPO
ECO
EPDM
Neoprene
HOPE
~o
~o
~o
0.4
1.0
0.9
0.1
~0
~0
0.1
0.2
1.0
~o
~o
~o
45.0
72.2
71.3
53.9
49.3
47.7
58.1
93.1
49.3
30.8
33.5
42.3
44.0
97.9
95.6
97.0
12.2
7.6
9.1
13.9
1.5
3.2
5.5
1.7
8.2
32.9
23.2
10.7
10.7
~0
~0
37.1
5.3
6.5
21.0
45.6
45.2
9.8
4.0
37.7
30.9
35.5
34.9
33.8
2.1
4.2
1.8
5.7
14.9
13.1
10.8
2.6
3.0
26.5
1.2
4.8
5.3
7.6
11.1
11.5
~0
0.2
1.2
PVC
~o
~o
~o
54.9
53.8
58.0
38.2
42.1
35.0
~o
~o
~o
6.9
4.1
7.0
Differential Scanning Calorimetry. Differential Scanning Calorimetry
(DSC) is a thermal technique that has a variety of applications in the
testing and evaluation of FMLs, other geosynthetics, and pipe. Among these
applications are its use for measuring the melting point, the amount of
crystallinity in semicrystal1ine polymers, i.e. PE, PP, and PB, and the
measurement of the thermal stability and the OIT of polymeric compositions.
This technique measures the heat of fusion and the oxidative induction time
of a crystalline structure; it can also give an indication of the modifica-
tion of semi crystal line compositions with other polymers by alloying. Thus,
this type of analysis can be used as a means of fingerprinting semi crystal!ine
4-101
-------
FMLs (particularly HOPE) and of assessing
to wastes. This technique is described
(1981), and Haxo (1983).
the effects of aging
by Boyer (1977), Ke
and exposure
(1966), Turi
1000
800
600
5
c
UJ
400
200
650°C
.
'
490°C
• Temperature
~10°C
Niti
rogen •
100
80
t-
o
60 u]
S
40 <2
oc
o
20
20
40
60 80 100
TIME, MINUTES
120 140
160
Figure 4-36. TGA of an exposed plasticized PVC FML.
The differential scanning calorimeter used in the work performed by
Matrecon was the Perkin-Elmer Model DSC-2C, equipped with an Intracooler I
subambient temperature accessory to provide an operating temperature range
of -40 to 725°C.
The instrument can characterize the thermal transitions, e.g. melting,
boiling, and changes in crystalline structure, of a material. When a sample
undergoes a thermal transition, an endothermic or exothermic reaction will
occur. These transitions are characterized by comparing the effects of
heating on the thermal characteristics of two cells that are simultaneously
heated or cooled so that the average cell temperature follows a preset
program. A weighed sample is placed in one cell and the other cell is a
reference cell, which is generally run empty so that all of the thermal
transitions in the tested material can be identified. The change in power
required to maintain the sample cell at the same temperature as the ref-
erence cell is recorded as a deflection of the recorder pen. The recorder
plots the temperature (°C) versus the differential energy flow (meal/sec)
required to maintain the sample cell temperature. An endothermic transi-
tion, such as melting, is shown as a positive peak; an exothermic reaction,
such as crystallization, is shown as a negative peak. The amount of energy
absorbed during the melting process may be determined by calculating the
peak area and relating it to the peak area resulting from the melting of an
indium standard of known weight. The energy absorbed is termed the "heat
of fusion" (AHf). Assuming that AHf for the fully crystalline polymer is
4-102
-------
known, the degree of crystal Unity of the sample can be determined as a
simple ratio. The magnitudes of these peaks and the temperatures at which
they occur are characteristic of the analyzed material. An example of a DSC
determination of PE crystallinity in an HOPE FML is shown in Figure 4-37.
o
LU
CO
o
s
h
Ul
<
oc
I
I I
Endotherm
396 K (123°C) = Melting Point
Exotherm
370 380 390 400
TEMPERATURE, KELVIN
410
Figure 4-37. DSC determination of the melting point and PE crystallinity in
an HOPE FML. The x-axis is the temperature which was raised at
5°C/min. The y-axis is calibrated in meal/sec, or rate of
energy flow. A positive deflection of the plot indicates that
the sample is absorbing energy (e.g. during melting).
To study the effect of the rate at which a material is cooled on cry-
stallinity content, Matrecon determined the crystallinity of specimens of the
same PE which were cooled at different rates. The material tested was a
sample of National Bureau of Standards' Standard Reference Liner Polyethylene
(NBS 1475), an HOPE. Crystallinity was deterimend using the method described
by Gray (1970a). Crystallinity contents were calculated from calorimetric
data obtained on specimens that had been heated to 157°C, then crystallized
4-103
-------
at cooling rates of 0.3125°, 10°, and 320°C per minute; the crystal Unity was
also calculated from the density specifications for this material. The DSC
results are presented in Table 4-24. This reference PE is certified to have
a density of 0.97844 g/cm3 with a standard deviation
0.00004 g/cm3 following conditioning as described in ASTM
data of Brandrup and Immergut (1966), the conditioned reference
calculated to be 80.9% crystalline after having been cooled
0.083°C/min. As is shown in Figure 4-38, sample crystal 1inity
related to the logarithm of the cooling rate up to a cooling rate
from the mean of
D1928. Using the
material is
at rate of
is linearly
of 10°C/min.
where it appears to level off. Thus, the percent crystallinity calculated
from the differential scanning calorimetric data is in good agreement with
the value calculated from the density. The samples cooled at 320°C/min. are
displaced from the regression because inadequate thermal conductivity and the
sample heat capacity effectively put an upper limit on the cooling rate. The
results indicate that cooling rate inversely affects the degree of crystal-
linity achieved.
TABLE 4-24. PERCENT CRYSTALLINITY AND MELTING TEMPERATURE OF
NBS STANDARD POLYETHYLENE 1475 WITH VARYING THERMAL HISTORY
Weight,
Sample mg
A 6.0
B 6.6
Melting
Cooling temperature, AHf, Crystallinity9,
rate, °C/min.
0.3125
10
320
0.3125
10
320
°C
136b
133
131
136
133
132
cal/g
50-52C
45
43
53
46
45
%
73-75
65
62
76
67
65
aCrystallinity value assumes that AHf = 69 cal/g for polyethylene in
perfect single crystal form (Gray, 1970b).
^Temperature at maximum endotherm.
cPeak off-scale; lower bound is measured value, upper is best estimate.
The melting points and percent of crystal!inity of a variety of PE FMLs
and films as determined by DSC is presented in Table 4-25. These data show
the pronounced differences between the different types of polyethylene and
the correlation of density and crystal!inity data. The standard reference
material is shown for comparison. The similarity of the results of testing a
sample of HOPE 307 that had been "quenched" at 160°/min. and an as-received
sample indicate that HOPE 307 had been cooled relatively rapidly during
manufacture.
The DSC can also be used to measure the oxidative induction time (OIT)
of a polymeric composition to assess its thermal stability and to assess the
various antioxidant packages that may be used in the preparation of the
polyethylene. 4_104
-------
a?
-0.01
0.1 1 10
Cooling rate, °C/min. (log scale)
100
1000
Figure 4-38.
Crystal Unity of NBS Standard Polyethylene 1475 as a function
of cooling rate. O derived from published data for NBS 1475,
Dfrom experimental data, Sample A; vfrom experimental data,
Sample B.
As is described in ASTM D3895, the material under test and the reference
are heated at a constant rate in an inert gas. When the desired temperature
has been reached, the gas is changed to oxygen at the same flow rate. The
material is then held at constant temperature until the oxidative reaction is
exhibited on the thermogram. The OIT is determined from data recorded during
the isothermal test.
Correlation of OIT to FML durability is improved by incorporating high
pressure oxygen to help accelerate testing at temperatures closer to the
actual high temperature stresses expected in the field (e.g. antioxidant
activity can change from very high-temperature testing to lower high-tempera-
ture testing) and to prevent loss of antioxidants which would occur at the
high temperatures.
This test is useful in assessing the thermal stability of the PE resin
in the FML or other PE product because of the several heatings and meltings
4-105
-------
TABLE 4-25. DIFFERENTIAL SCANNING CALORIMETRY OF SELECTED POLYETHYLENES
Melting Points and Percent Crystal!inity
Type
LDPE
LLDPE
HDPE-alloy
HOPE
HOPE
HOPE
-P>
I HDPE
HOPE
HDPE
Liner
number^
21
284
181
99
105
184
288
307
...
Thickness,
mil
10
30
30
100
30
30
100
80
Pellet
Density3,
g/cnr
0.935
0.931
0.948
0.943
0.950
0.953
0.945
0.947
0.9789
Carbon black
content0, %
0
2.4
4.0
d
0
2.0
1.8
2.6
0
Feature
Clear
Black
Alloyed with EPDM
Shiny side of sheeting
Dull side of sheeting
As received
After drawing
As received
"Quenched"6
"Anneal ed"f
European production
As received
"Quenched"6
"Annealed"f
Reference"
Melting
point,
°C
97-100
100-123
133
124-129
124-125
130
131-133
134
132
135
129
124
123.5
127
136
Crystal -
1 inity,
29
39
43
46-48
47
66-67
62-64
69
69
<70
53
48
48
55
75
determined in accordance with ASTM D792.
^Matrecon liner identification number.
cBy thermogravimetric analysis.
dShiny side of sheeting had a carbon black content of 1.9%:
of 1.4%.
eCooled at 160°C/min.
fCooled at 10°C/min.
9From NBS certificate.
"National Bureau of Standards' Standard Reference Material
dull side had a carbon black content
NBS 1475; cooled at 0.3125°C/min.
-------
that the base resin goes through during fabrication and in welding of an FML
or a pipe during installation in the field.
Melt Index. Melt index is the flow rate of a thermoplastic as deter-
mined by an extrusion plastometer specified in ASTM D1238. The rate of flow
through a die of a specified length and diameter under prescribed conditions
of temperature, load, and piston position in the barrel at the time of test
is measured. Values are reported as the rate of extrusion in grams per 10
min. at the temperature and load at which the test is run. This test is used
in the quality control of PE resins. The constancy of the melt index value
within a narrow tolerance range ensures consistent molecular weight and
Theological properties. Melt index values in flow rates are also helpful in
indicating the process properties of a resin. It should be noted that the
melt index of a PE FML will be equal or less than that of the PE resin from
which it was manufactured due to slight changes in the PE caused by the
processing.
4.2.2.5.2 Physical-mechanical properties—Appropriate or applicable
test methods for testing the physicalproperties of polymeric FMLs are
presented in Table 4-26.
Tensile Properties. Tensile tests are probably the most widely used
tests in the rubber and plastics industries for evaluating polymeric compo-
sitions and products because tensile properties give a good indication of
the quality of the compound of a specific polymer. Tensile properties of
polymeric materials are generally measured in tension by a stress-strain
test. The specific properties that are measured depend on the type of FML.
They include:
- Tensile stress at yield (if a semicrystalline FML).
- Elongation at yield (if a semicrystalline FML).
- Tensile stress at fabric break (if fabric reinforced).
- Elongation at fabric break (if fabric reinforced).
- Stress at specified elongations (e.g. 100% and 200%).
- Tensile stress at break of FML.
- Elongation at break of FML.
The test method used, including the type of test specimen required and
the rate at which a specimen is elongated, varies with the type of FML being
tested (Table 4-26). The method used, particularly the type and size of the
test specimen, may also depend on the purpose of the test. For instance, in
the compatibility of a fabric-reinforced FML, l-in.-wide strip specimens are
preferred over 4-in. wide grab test specimens due to the limited size of the
exposed sample. However, for quality control testing and specification
testing, 4-in or even wider specimens are preferred.
4-107
-------
TABLE 4-26. APPROPRIATE OR APPLICABLE METHODS FOR TESTING THE PHYSICAL PROPERTIES OF POLYMERIC FMLS
o
oo
FML without fabric reinforcement
Property
Thickness (total)
Coating over fabric
Tensile properties
Tear resistance
Modulus of elasticity
Hardness
Puncture resistance
Hydrostatic resistance
Seam strength:
In shear
In peel
Ply adhesion
3NSF, 1985.
bU.S. GSA, 1980.
na = Not applicable.
Thermoplastic
ASTM D638
na
ASTM D882/D638
ASTM D1004
(modified)
na
ASTM D2240
Durometer A or D
FTMS 101C,
Method 2065°
na
ASTM D4437/D882,
Method A
(modified)
ASTM D4437/D413
na
Crossl inked
ASTM D412
na
ASTM D412
ASTM D624, Die C
na
ASTM D2240
Durometer A or D
FTMS 101C,
Method 2065&
na
ASTM D882,
Method A
(modified)
ASTM D413
na
Semi crystal line
ASTM D638/D374
na
ASTM D638
(modified)
ASTM D1004
ASTM D882, Method A
ASTM D2240
Durometer A or D
FTMS 101C.
Method 2065&
ASTM D751, Method A
ASTM D4437/D882,
Method A
(modified)
ASTM D4437/D413
na
Fabric reinforced
ASTM D751, Section 6
Optical Method3
ASTM D751, Methods A & B
(ASTM D638 on selvage)
ASTM D751, Tongue Method
(8 x 8-in. test specimen3)
na
ASTM D2240
Durometer A or D
(selvage only)
FTMS 101C,
Methods 2031 & 2065&
ASTM D751, Method A
ASTM D751, Grab Method
(modified3)
ASTM D882,
Method A
(modified)
ASTM D413
ASTM 04 13
ASTM D751, Sections 39-42
-------
For a given polymeric FML, tensile properties will vary with speed of
test, specimen size, direction of test with respect to the grain in the
sheeting, temperature, and humidity. The sensitivity of the tensile prop-
erties of FMLs indicates the need for strict conformance to the specified
procedure in specification testing. Semi crystalline FMLs are particularly
sensitive to rate of test. The results of testing an HOPE FML at 20 ipm are
significantly different from the results of testing the same FML at 2 ipm.
Absolute values of the tensile strength of the compositions of different
polymers should not be compared unless tensile strength is required in the
performance of the product.
Changes in tensile properties can be used to monitor the effects on
an FML of exposure to wastes. In many rubber and plastics applications,
either a 50% loss in tensile strength or elongation or a 50% increase or
decrease in modulus (i.e. stress at a specified elongation) is taken to
indicate that the product is no longer serviceable in the specific applica-
tion. These criteria are probably not applicable to FMLs; nevertheless,
major changes of properties within a relatively short exposure period
indicate the incompatibility of an FML with the specific waste.
Modulus of Elasticity. The modulus of elasticity is commonly used as
a measure of the stiffness or rigidity of a semi crystalline FML, such as
HOPE. It is defined as the ratio of stress to strain in the part of the
stress-strain curve that is linear, particularly at low stresses. Over this
range of stress, the material is said to follow Hooke's law, which says that
stress is proportional to strain. The modulus is expressed as force per unit
area. In tension, this property is also known as Young's modulus.
The modulus of elasticity of the semi crystalline FMLs is generally
measured by one of two methods:
- ASTM D882, in which a standard-size strip specimen is extended in
tension at a strain rate of 0.1 in./in.-min. The elongation is
monitored by the jaw separation. The slope of the straight line
portion of the stress-strain curve is taken as the modulus of elas-
ticity.
- ASTM D638, in which a standard dumbbell specimen is extended at a
standard rate, usually of 2 in./min. The elongation is monitored by
following the bench marks using an extensometer. The slope of the
straight line portion of the stress-strain curve is taken as the
modulus of elasticity.
In view of the approximate relationship of the modulus of elasticity, Y, to
the modulus of rigidity, G, i.e. Y = 36, the modulus of rigidity can be
measured in torsion, in accordance with ASTM D1043 and ASTM D1053, and the
modulus of elasticity calculated using the equation. Modulus of elasticity
also can be measured in flexure, in accordance with ASTM D797.
Due to the variations in test conditions and the speed of test, the
values for the elastic modulus vary, but are reproducible for a given
method. Regardless of the method of determining the modulus of elasticity,
4-109
-------
the limitations of applying the term "modulus of elasticity" to polymeric
materials must be recognized, as is indicated in "Note 4" of ASTM D638:
Since the existence of a true elastic limit in plastics (as in
many other organic materials and in many metals) is debatable,
the propriety of applying the term "elastic modulus" in its
quoted generally accepted definition to describe the "stiffness"
or "rigidity" of a plastic has been seriously questioned. The
exact stress-strain characteristics of plastic materials are
highly dependent on such factors as rate of application of
stress, temperature, previous history of specimen, etc. However,
stress-strain curves for plastics, determined as described in
this test method, almost always show a linear region at low
stresses, and a straight line drawn tangent to this portion of
the curve permits calculation of an elastic modulus of the
usually defined type. Such a constant is useful if its arbitrary
nature and dependence on time, temperature, and similar factors
are realized.
Nevertheless, the determination of modulus of elasticity serves as a good
measure of the stiffness or rigidity of a polymeric material, and, if
measured in a consistent and reproducible manner, it can be used to measure
variability in a material and changes due to different aging effects.
In the present version of EPA Method 9090 (EPA, 1986), modulus of elas-
ticity testing of semicrystal line FMLs is required in accordance with ASTM
D882. However, because of the limited size of the samples that can be placed
in exposure, a test specimen smaller than the D882 standard size is used.
Even though the strain rate for the smaller specimens is equal to that of the
standard specimen, the results of testing the smaller specimens are lower.
Modulus of elasticity can also be measured in accordance with ASTM D638,
which calls for a dumbbell specimen.
Hardness. Hardness is defined in terms of standard tests for hardness
of polymeric materials; it is the ability of a material to resist indentation
by a small probe of specified shape and dimensions. Although no simple
relationship exists between hardness and other measured properties, hardness
is related to the modulus of elasticity, Young's modulus (ASTM D1415). It is
easily measured and can be used to assess changes in an FML during exposure
to wastes and weather.
Hardness testing is usually performed in accordance with ASTM D2240.
Test values are reported as a value followed by a letter which indicates the
type of durometer that was used. The scales overlap somewhat; Duro A of 90
approximately equals a Duro D of 40. If a material has a value greater than
80 with the Type "A" durometer, it should also be tested with the Type "D"
durometer.
Tear Resistance. Tear resistance is the force required to tear a
specimen that has a controlled flaw. The value can indicate the mechanical
strength of an FML, particularly with respect to the types of stresses
4-110
-------
imposed during installation. Tear resistance can also be used to monitor
the effects of an exposure on an FML. The tear value depends on both the
rate of test, and the shape and size of the test specimens.
The tear resistance of fabric-reinforced FMLs is determined in accord-
ance with a modified version of the Tongue Tear Method in ASTM D751, which
calls for a 3 x 8-in. test specimen that tears along a line parallel to the
8-in. direction. However, because of the relatively low strength of the
adhesive bond between the fabric and the polymeric coating in many fabric-
reinforced FMLs, an 8 x 8-in. test specimen is generally used in testing
fabric-reinforced FMLs (NSF, 1985). The low adhesion allows the fabric
threads to bundle at the top of the tear and give false high values or to
pull out of the coating matrix and yield false low values.
Puncture Resistance. Puncture resistance is the force required to
puncture a sheeting with a standard probe. The value is an indication of the
ability of a material to withstand puncture from above (i.e. by equipment,
foot traffic, deer hooves, etc.) and from below (i.e. by irregularities in
the substrate, etc.). Puncture resistance can be used to assess the effects
on an FML of exposure to an environment.
Two methods frequently used for assessing the puncture resistance of
polymeric FMLs are:
- Federal Test Method Standard (FTMS) 101C, Method 2031—Tetrahedral-
Tip Probe Method (U.S. GSA, 1980).
- Federal Test Method Standard 101C, Method 2065--l/8-in. Radius-
Tip Probe Method (U.S. GSA, 1980).
In FTMS 101C, Method 2031, a tetrahedral-tip probe punctures a 10 x 4-in.
specimen which has been looped around the point of the probe. The test is
presented schematically in Figure 4-39. This method has been used particu-
larly for assessing the puncture resistance of fabric-reinforced FML because
the probe is large enough to cut and break several cords during test.
In FTMS 101C, Method 2065, a 1/8-in. radius-tip probe punctures a
2 x 2-in. square test specimen that is confined between two plates in which
a 1-in. diameter hole has been drilled. A drawing of the probe and sample
holder is presented in Figure 4-40. Method 2065 is particularly useful for
measuring the puncture resistance of unreinforced sheetings. The applica-
bility of this test to fabric-reinforced FMLs is limited because of the
openness of the weaves normally used in fabric reinforcement. The openness
of the weave can result in the probe's passing between the threads or in the
probe's breaking one or two threads when the FML is punctured.
The ASTM D35 Committee is reviewing the puncture test and is presently
considering a 5/16-in. diameter probe with a flat tip beveled 1/32 in.
around its circumference.
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UPPER JAW
SPECIMEN
PUNCTURE FIXTURE
PROBE
LOWER JAW
Figure 4-39. Puncture assembly for the tetrahedral tip probe, FTMS 101C,
Method 2031 (not to scale) (Source: U.S. GSA, 1980).
Hydrostatic Resistance. In the hydrostatic resistance test a column of
water isforcedthrougha test specimen until the specimen bursts. The
reported value is the maximum value before rupture of the specimen. The test
is important because it can indicate the biaxial stress-strain behavior of a
sheeted material. The machine required to perform this test is presented in
Figure 4-41. The minimum size test specimen is a 4-in. diameter disk (ASTM
D751). The specimen is held between two annular plane clamps which have
coaxial apertures in their centers. When the clamps are closed together
around the test specimen, a seal is formed. Hydrostatic pressure is applied
to the underside of the clamped specimen, which is 1.75 in. in its unsup-
ported diameter, until leakage of the specimen occurs, i.e. the specimen
ruptures. This pressure is generated by means of a piston forcing water into
the pressure chamber at a specified rate.
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SPECIMEN
CAGE
PUNCTURED
SPECIMEN
SHEETS OF
CARBORUNDUM
PAPER
PROBE PLATE
Figure 4-40.
Jig for puncture
101C, Method 2065.
resistance and elongation test, FTMS
(Source: U.S. GSA, 1980)
This test is used primarily with coated fabrics, such as fabric-rein-
forced FMLs, but it can also be used to measure the hydraulic burst strength
of semi crystal line FMLs. This method is not applicable to many unreinforced
thermoplastic and crosslinked FMLs because the biaxial elongation of these
materials exceeds the dimensions of the cavity above the test specimen in the
testing machine. Used with a diaphram to seal the water, the testing equip-
ment is used to measure the bursting strength of fabrics, both woven and
nonwoven.
Seam Strength of Factory and field Systems. The integrity of the seams
is a critical factor in the functioning and durability of an in-service FML.
Seams are tested to ensure that the method of seaming a particular material
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CLAMP SCREW
HAND WHEEL
SPLASH
PROOF SHIELD
TEST SPECIMEN
CLAMP FACINGS
O-RINC
CHAMBER FILLED
WITH WATER
PLUNGER ASSEMBLY
Figure 4-41. Schematic of hydrostatic resistance test machine.
4-114
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is adequate. Tests are also performed as part of immersion and compatibility
tests with waste liquids and with standard fluids, because the effects of
various liquids on seams vary, particularly with seams fabricated with ad-
hesives. Seams are tested in shear and peel modes, both using an increasing
load and under a constant load until breakage.
Shear strength testing is performed by applying a force across the seam
in a direction parallel to the plane of the bond, thus subjecting the bond
interface to a shearing force. In most specification testing, a constant
rate of extension testing machine is used; however, in some on-site testing
during installation, manually powered screw-type devices have been used.
At present there is no standard test method intended specifically for
testing FML seams in shear. One of the methods most frequently cited for the
shear testing of seams made from unreinforced FMLs is ASTM D882, which is a
strip tensile test method intended for determining the properties of plastic
sheeting less than 0.04 in. in thickness. Also cited are ASTM D3083 and
D638, either by themselves or in conjunction with ASTM D882. ASTM D3083 is a
specification for PVC sheeting which specifies the use of ASTM D882 for seam
testing with some modifications. ASTM D638 is a dumbbell tensile test method
intended for determining the properties of plastic sheeting greater than 0.04
in. in thickness. All of these test methods need to be modified to be used
for shear testing of seams.
The types of specimens that have been used for shear testing of seams
fabricated from unreinforced FMLs have included strips 0.5-1.0 in. in width,
ASTM D638 Type I dumbbells (which feature a 0.5 in. narrow width test area),
and ASTM D638 Type IV dumbbells (which feature a 0.25 in. narrow width test
area). The dumbbell test specimens have been used in cases where it was
necessary to localize the tensile stress in the seam part of the sample and
away from the grips, as in the case of seams fabricated from semi crystal line
FMLs. Testing of seams made with reinforced FMLs is often performed in
accordance with a modified version of ASTM D751 Grab Method. In the modi-
fication, the distance between the clamps at the start of test is 6 in. plus
the seam width (Figure 4-42). Total length of the test specimen is 9 in.
plus the seam width.
ASTM D4437, "Standard Practice for Determining the Integrity of Field
Seams Used in Joining Flexible Polymeric Sheet Geomembranes," cites ASTM
D816, Method B, as the procedure for testing shear strength. ASTM D4437
modifies ASTM D816 and recommends a minimum of five 1-in. wide specimens
for unreinforced FMLs and a minimum of five 2-in. wide specimens for fabric-
reinforced FMLs. Recommended initial grip separation is 2 in. plus the width
of the seam and the recommended crosshead speed is 2 ipm. The test specimen
should be fully supported within the grips across the width of the specimen.
Peel testing is performed by applying a load such that the bonded
interface is subjected to a peeling force that attempts to separate the two
FMLs that have been seamed together. The peel strength of seams, particular-
ly for seams fabricated with adhesives, is more sensitive to the effects of
aging and exposure than their shear strength. Laboratory peel testing of all
4-115
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types of FMLs is often performed in accordance with ASTM D413 at a jaw
separation rate of 2 ipm. Testing can be performed either in 90° or 180°
peel (Figure 4-43). Peel testing of semi crystal line FMLs in 180° peel is
difficult to perform because of their stiffness. In testing seams fabricated
SEAM
4Vj
CLAMP
Figure 4-42. Seam strength specimen for testing seams of fabric-reinforced
FMLs in accordance with ASTM D751, modified.
4-116
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from fabric-reinforced FMLs 1-in. wide strip specimens are usually used. In
testing seams fabricated from semi crystalline FMLs, ASTM D638 Type I and Type
IV dumbbell specimens have sometimes been used to localize the peeling force
in the seam test area. ASTM D4437 cites methods ASTM D413, Method A (Machine
Method, Strip Specimens—Type A), which is a 180°-peel method, and ASTM D816,
Method C, which can be either a 90°- or a 180°-peel method. Both methods are
modified so that a minimum of five 1-in. wide specimens are tested with an
initial grip separation of 1 inch. Testing is performed with a crosshead
speed of 2 ipm.
(a) 90° peel (b) 180° peel
Figure 4-43. Two configurations of peel testing.
Test results can be reported either as a maximum or an average peel
value. ASTM D413 requires the average value over the seam test area, but in
cases in which the seam test specimens break through one of the FML sheets
or through a weld bead rather than delaminate along the contact interface
between the two sheets, often only a maximum value can be reported. Care
should be taken in noting how the reported peel values are calculated.
Peel testing using a static or "dead load" at room
elevated temperatures can provide a good indicator of time-dependent weak-
nesses that will not be observed under dynamic testing. Dead load testing at
elevated temperatures can be used as a method of revealing the sensitivity of
a seam system to long-term exposures on the FMLs and the seaming system.
at room temperature and at
of time-dependent weak-
a. Dead load testina at
Hessel and John (1987) suggest a quantitative factor for the long-term
behavior of welded seams of PE FMLs by carrying out creep tests in a solution
wetting agent at 80°C and a load of 600 psi (4N/mm2). The
ratio of the tension creep of the weld to the creep of
containing a
welding factor is the
the parent material.
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4.2.2.5.3 Permeability characteristics—Liquids or gases per ^e_ do not
permeate homogeneous nonporous FMLs but do permeate FMLs as vapors or gases
on a molecular scale. The rate of permeation depends on the solubility of
the liquid and the diffusibility of the dissolved molecule in the FML. The
permeability of FMLs to different species can vary by orders of magnitude.
Tests to measure the permeability of FMLs to different species include
the following:
- Water vapor transmission, ASTM E96, Inverted Water Method (Procedure
BW).
- Solvent vapor transmission, ASTM E96, Inverted Water Method (Procedure
BW), modified.
- Gas permeability, ASTM D1434, Procedure V--Volumetric.
- Pouch test, Appendix D.
These tests are discussed in Section 4.2.2.4.1, "Permeability." All of these
tests can be used to determine the permeability characteristics of all types
of FMLs with the exception of the pouch test. Because of the difficulty in
forming seams of narrow widths in crosslinked FMLs, it is not possible to
use the pouch procedure in testing crosslinked FMLs. The pouch test also
functions as a long-term exposure to a waste or test liquid.
4.2.2.5.4 Tests to measure the effects of environmental or accelerated
exposure—Appropriate or applicable methods for determining the effects of
environmental or accelerated exposure are listed in Table 4-27. The follow-
ing paragraphs discuss these tests.
Ozone-Cracking. FMLs must be resistant to ozone-cracking. Ozone can
be particularly damaging to and cause severe cracking in polymers that have
unsaturation in their main chains. Of the polymers that have been used in
FMLs, only butyl and neoprene have unsaturation in their main chains. ASTM
D1149 estimates the resistance of a sample to cracking when exposed to an
atmosphere containing ozone. Specimens are kept under a surface tensile
strain, and the ozone content or partial pressure in the test chamber is
maintained at a fixed value.
Environmental Stress-Cracking. A stress-crack is defined as either
an externalor internal crack in a plastic that is caused by tensile stress
less than its mechanical strength as measured at standard rates. Under
conditions of simultaneous stress and exposure to chemicals (e.g. soaps,
oils, detergents, or other surface-active agents), some plastics, such
as PE, can fail mechanically by cracking. A test can be run that indicates
the susceptibility of a PE sheeting to stress-cracking by exposing bent
specimens with controlled imperfections to a designated surface-active agent.
ASTM D1693, though commonly used to measure susceptibility to stress-crack-
ing, has limitations for assessing the long-term resistance in service of
FMLs to cracking. In this test 10 notched and bent strip specimens are
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TABLE 4-27. APPROPRIATE OR APPLICABLE METHODS FOR DETERMINING EFFECTS
OF ENVIRONMENTAL OR ACCELERATED EXPOSURES ON POLYMERIC FMLS
FML without fabric reinforcement
Property
Ozone-cracking
Environmental stress-
cracking
Low-temperature testing
Tensile properties at
elevated temperature
Dimensional stability
Air-oven aging
Water absorption
Liner/waste compati-
bility
Soil burial
Pouch test
Outdoor exposure:
Test slabs
Bent loops
Tub test
Accelerated outdoor
weathering (EMMAQUA)
Thermoplastic
ASTM D1149
na
ASTM 01790
ASTM D638
(modified)
ASTM D1204
ASTM D573
(modified)
ASTM D570
EPA 90903
ASTM D471/D543
ASTM D3083
Appendix D
ASTM D1435
ASTM D518
Appendix H
ASTM D4364
Crossl inked
ASTM D1149
na
ASTM D746
ASTM D412
(modified)
ASTM 01 204
ASTM 0573
(modified)
ASTM 0471
EPA 90903
ASTM 0471
ASTM 03083
na
ASTM 01435
ASTM 0518
Appendix H
ASTM D4364
Semi crystal line
na
ASTM 01693
ASTM 01790/0746
ASTM 0638
(modified)
ASTM 01204
ASTM 0573
(modified)
ASTM 0570
EPA 9090a
ASTM 0543
ASTM D3083
Appendix 0
ASTM 01435
ASTM 0518
Appendix H
ASTM 04364
Fabric reinforced
ASTM 01149
na
ASTM 02136
ASTM 0751, Method B
(modified)
ASTM 01204
ASTM 0573
(modified)
ASTM 0570
EPA 90903
ASTM 0471/0543
ASTM 03083
Appendix D
ASTM 01435
ASTM 0518
Appendix H
ASTM 04364
aEPA, 1986.
na = Not applicable.
-------
immersed in a detergent solution, and the time it takes before 5 of the 10
specimens break is determined. The test apparatus is shown schematically in
Figure 4-44. This method is not suitable for testing PE seams.
[ft
- Notch
Test Specimen
Specimen Holder
Test
Assembly
Figure 4-44.
Specimen and equipment of ASTM D1693 for bent-strip test
specimen is 0.5+0.03 in x 1.5±0.1 in. The holder is 6.5 in. in
length and 0.463±0.002 in. in inside width. It holds 10
specimens. The holder with specimens is placed in a 32 x 200
test tube fitted with an aluminum foil wrapped cover.
mm
notch cut in the specimen
varies in depth depending
(Based on ASTM D1693).
is 0.750±0.005 in.
on the thickness of
The
in length and
the sheeting.
Another method used to measure the tendency of a semicrystalline product
to break when exposed simultaneously to stress and a detergent solution is
ASTM D2552. In this test, 20 dumbbell specimens are placed under constant
load, and the time it take before 10 of the 20 specimens break is determined.
The test apparatus is shown schematically in Figure 4-45. This method has
been used to test seams by selecting a dumbbell with a neck section of
sufficient length to test the full width of the seam and by modifying the
specimen holders accordingly.
Crissman (1983) has proposed another test where the specimen is con-
strained in a fixed geometry by binding it around a cylindrical metallic
form and subjecting it to a constant applied stress, as is shown in Figure
4-46.
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2O POSITIONS
SHOT
CAN
SIDE VIEW
SPECIMEN
FRONT VIEW
TRAY MOVED UP AND
DOWN ON RACK AND
PINION ARRANGEMENT
Figure 4-45.
Schematic view of constant-load stress rupture test
apparatus of ASTM D2552. (Based on ASTM D2552).
Low-Temperature Properties. Liners can encounter low temperatures
before installation, during installation, and in some cases during service
depending on the climate in which they are installed.
Some FMLs are quite sensitive to low temperature, becoming stiff and
even brittle on exposure to moderately low temperatures. The rate varies at
which these changes take place as does the time it takes for a material to
soften when the temperature is raised. Some changes can take an extended
time; consequently, short-term tests can be quite misleading. A variety of
tests exist for measuring the effects of low temperatures on materials.
Brittleness test methods are some of the most available. However, they
vary greatly in low temperature soak time, rate of test, configuration of
specimen, etc.; consequently, even for a given polymer type, results can vary
greatly, depending on thickness of specimen, time of soak and the specific
test used. Some of the commonly used low temperature tests are:
ASTM D746 -
Brittleness
Impact.
Temperature of Plastics and Elastomers by
ASTM D1034 - Stiffness Properties of Plastics as a Function of Temper-
ature by Means of a Torsion Test (also used on rubber
compositions).
ASTM D1790 - Brittleness Temperature of Plastic Film by Impact.
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ASTM D2136 - Low Temperature Bend Test of Coated Fabrics.
ASTM D2137 - Brittleness Point of Flexible Polymers and Coated Fabrics.
High-Temperature Properties. An FML may encounter higher than normal
temperatures prior to installation, during installation, and during service.
Thermoplastic FMLs, if allowed to be exposed to heat as rolled or folded
panels prior to installation, such as being left in the sun, can block
or stick together; when unfolded, a coated FML may split or an unreinforced
FML may tear and become unserviceable. During installation, a black FML
can reach temperatures of more than 160°F (71°C). At such temperatures,
tensile and tear strengths can be significantly lower than at normal test
modulus, and tear tests can be run at
indicate the effects of elevated temper-
percent crystallinity in semi crystalline
1966). The results of some high temper-
ature testing are presented in the paragraph "Effect of Temperature on
Properties" in Section 4.2.E.4.2 above.
temperatures. Appropriate tensile,
temperatures of 60°C or higher to
ature. At such temperatures the
polymers, such as PE, drops (Miller,
TANK-
Figure 4-46. Schematic of a proposed test method for determining
environmental stress-cracking resistance. (Source:
Crissman, 1983).
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Dimensional Stability. In addition to causing changes in the mechanical
properties of an FML, higher temperatures can also cause shrinkage and dis-
tortion due to relaxation of stresses in an FML compound, particularly in
unreinforced thermoplastic FMLs. ASTM D1204 measures changes in the linear
dimensions of 10 by 10-in. specimens resulting from exposure at 100°C for
"the length of time applicable to the material being tested."
Water Absorption. The absorption of water can adversely affect many
polymeric compositions. Since most waste liquids contain water, the effects
of immersion in water on FMLs should be determined as part of the selection
process. The effects of immersion are evaluated by changes in weight,
dimensions, or properties. A water absorption test, such as ASTM D471 and
D570, can be included in a test program to provide a relatively precise
comparative index. (Note: ASTM D471 covers the testing of cross!inked
materials and ASTM D570 covers plastics.) In performing these tests, ex-
tended immersion of specimens until the weight is constant is recommended.
To assess the effects of water absorption on tensile properties, suf-
ficiently large strips can be immersed so that tensile specimens can be died
out of them and tested. Precut tensile specimens can also be used. Water
absorption tests at elevated temperatures accelerate the effects of immer-
sion. However, test results have indicated that tests at 70°C and above are
too severe to serve as accelerated aging tests for most FMLs (Haxo et al,
1982, p 87).
Liner/Waste Compatibility Testing. The compatibility of a candidate
FML with the leachate or waste liquid to be contained is an essential con-
sideration in making the final choice of an FML for use as a liner in a waste
storage or disposal facility.
The EPA has developed Method 9090 to determine the compatibility of FMLs
and waste liquids. In this test, samples in slab form are immersed for up to
four months at 23°C and 50°C in a representative sample of the waste liquid
or leachate to be contained. Physical and analytical testing are performed
on the unexposed FML for baseline data and on samples after exposure to the
waste liquid for 30, 60, 90, and 120 days. Thus, the entire test involves
many steps including:
- Selecting representative or appropriate samples of the waste liquid or
leachate and the FML.
- Exposing the FML samples to the waste liquid or leachate under highly
controlled conditions.
- Testing the physical and analytical properties of the unexposed and
exposed FML samples.
- Interpreting the final results.
This test is discussed in detail in Chapter 5.
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In cases which do not require testing in accordance with Method 9090,
such as in the selection of an FML for secondary containment of an under-
ground storage tank, the candidate FMLs should still be tested in immersion
tests. Recommended immersion tests include ASTM D471 and D543. Sufficiently
large strips can be immersed in these tests so that tensile specimens can be
died out of the strips and tested in order to indicate the effects of immer-
sion on tensile properties.
Pouch Test. The pouch test, described in Appendix D, can be used to
measure the permeability of polymeric FMLs to water, organics, test liquids,
or ions, and dissolved organics and is, at the same time, a one-sided ex-
posure test. In this test, a waste liquid or test liquid is sealed in a
pouch made of the FML under study. The pouch is then placed inside a con-
tainer filled with deionized water or a liquid of known composition. At
regular intervals, the pouch is removed and weighed to monitor the movement
of water or the test liquid through the pouch walls. The electrical con-
ductivity of the liquid outside the pouch is measured regularly to evaluate
the permeation of ions through the pouch walls. At the end of the exposure
the pouch is dismantled, and the pouch walls are tested for physical and
analytical properties. Because of the difficulty of making narrow width
seams with cross!inked FMLs, this procedure can only be used to test thermo-
plastic FMLs. Selected data from pouch tests are presented in the paragraphs
in Section 4.2.2.4.1 on the permeability of FMLs to ions and the permeability
of FMLs to organics. Results of pouch tests are also discussed in Chapter 5.
Outdoor Exposure Tests. As most FMLs are exposed to the weather at
some time during installation and/or service, outdoor exposure tests should
be performed. Four tests in which FMLs can be exposed to weathering are:
- Outdoor exposure of test slabs on a rack.
- Exposure as bent loops.
- Exposure as liners in tubs filled with a waste liquid.
- Accelerated weathering test (EMMAQUA).
Outdoor Exposure of Test Slabs—Exposing small slabs of FMLs to
ambient weather conditions on panels that face due south at a 45°
angle gives an indication of the weatherability of an FML. In
this exposure, samples are exposed to UV light, oxygen, ozone,
heat, and wind. Changes in physical and analytical properties as
well as surface appearance after exposure can indicate relative
differences between compounds of different polymer types and
among compounds of one polymer type. ASTM D1435 details a
procedure for outdoor exposure on test racks.
Bent Loops —In the bent loop test (ASTM D518, modified), small
specimens of FMLs are bent into loops, which are exposed to the
weather. This test combines exposure to weather (as in roof
exposure of test slabs) with exposure to stress provided by the
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bent loop. The specimens are inspected regularly for signs of
cracking or crazing on the FML surface. This test can be used
only qualitatively in the FML selection process.
Tub Test—The tub test, described in Appendix H, can evaluate
liner/waste compatibility in a configuration that simulates some
actual field conditions. A small tub is placed where it is
exposed to the weather. The tub is lined with a seamed sheet of
the FML which is carefully folded into place. The tub is then
filled approximately 3/4 to 7/8 full with the waste. The waste
level is allowed to drop 4 inches by evaporation before the tub
is refilled with tap water. Overflow is avoided by covering the
tub during periods of precipitation. This test provides exposure
to sunlight, a range of temperatures, and ozone, as well as to
the test waste. A horizontal area around the tub at the water-
line is intermittently exposed to weather and to waste as the
waste level fluctuates. Extended exposures of several years
duration are recommended. After exposure the various exposed
areas of the FML are subjected to physical and analytical tests.
This test is semiquantitative and can identify some of the
exposure conditions that are detrimental to the FML being tested.
Results of tub tests are presented in Chapter 5.
Accelerated Outdoor Weathering Using Concentrated Natural Sun-
1jght--A procedure has been developed for accelerating the
effects of outdoor exposure on coatings and polymeric products,
including FMLs (ASTM D4364 and G-90). Specimens are exposed in a
test machine that concentrates the sun's rays on a test specimen.
The test machine follows the sun and has ten flat mirrors,
positioned in such a way that the sun's rays strike them at
near-normal incident angles while in operation. These mirrors
reflect concentrated sunlight onto an air-cooled target board on
which specimens are mounted. Maximum sample size, which is 5 x
55 in. in the ASTM D4364 and G-90 design, is limited by the size
of the mirrors. Exposure can be either with or without water.
Exposure with water involves spraying water on the exposure
samples in a regular, cyclic fashion. This exposure is also
known as the EMMAQUA (Equatorial Mount with Mirrors for Acceler-
ation plus water spray) test. Samples are exposed either for a
specified time period or until a specified quantity of solar
irradiation has been reached. Samples can be visually in-
spected for changes in general appearance, checking/crazing,
cracking, blistering, warping. After exposure, the physical and
analytical properties can also be measured.
The test machine can be used to determine the effects of weather-
ing in test times considerably shorter than conventional south-
facing racks under natural weathering conditions. It is esti-
mated that one year exposure in the test machine equals 8 years
of exposure to natual weathering. The effectiveness of the test
machine depends primarily on the amount and character of the
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ultraviolet in the direct beam component of the sunlight. Thus,
this test requires climatic conditions with sufficient short
wavelength ultraviolet in the direct beam, i.e. desert or high
altitude environments which are also not regions of diffuse
irradiance.
Some specifications are now requiring that FMLs to be used as
exposed (as opposed to buried) liners shall pass the EMMAQUA test
for a minimum of 1,000,000 langleys with a rating of 7 or better,
i.e. have no checks greater than 0.006-in. wide.
Morrison and Parkhill (1987) have indicated that a 1-yr EMMAQUA
exposure, which exposed FML samples to 1.45 x 106 langleys, was
too long resulting in weathering conditions that were too severe
for some materials, particularly the PEs, causing thermal degra-
dation that may not occur in long-term exposure to natural
weathering. Further studies are recommended to determine if the
EMMAQUA exposure of FMLs correlates with field exposure.
4.2.2.5.5 Performance tests—Performance tests attempt to simulate in
the laboratory the mechanical behavior of an FML in the field in order to
determine the actual engineering properties needed for designing a liner
system. At present, all performance tests of FMLs are developmental rather
than standard.
Stress-Strain Behavior of FMLs. The usual tension test used to deter-
mine Thestress-straincharacteristics of unreinforced FMLs uses a small
"dogbone"-shaped test specimen. Such specimens are convenient since failure
always occurs within the central, narrowed test zone and since they require
little material, are easy to form, and can be held in the grips of a test
machine without slipping. The shape and size, however, are inadequate to
predict full-scale stress-strain behavior of an in-service FML. The behavior
of a large, i.e. wide, FML can better be reflected by a wide-width tensile
specimen and a corresponding test method; just how wide is left up to the
user's discretion. ASTM Committee D35 on geotextiles and related products
has decided on an 8-in. wide specimen and a 4-in. initial jaw separation
(ASTM D4595). While this method is primarily intended for the testing of
geotextiles, it can be used for FMLs. One problem with this test method is
that the test specimens often fail at the face of the clamps where stress
concentrations exist. This, in turn, might be avoided by using roller grips,
which are typically used in testing high strength geotextiles, but using
roller grips necessitates monitoring deformations with an external device
such as a laser or infrared tracking device.
Even the wide-width tensile specimen test, however, does not truly
simulate in situ behavior since there are no stresses acting on the surfaces
of the FML. FMLs in the field invariably have soil above and below them, and
this undoubtedly influences their tensile behavior. Confinement between
these two layers must be simulated in order to have an accurate performance
test. McGown et al (1982) have developed a test apparatus to simulate in-
soil stress-strain, creep, and stress relaxation behavior.
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The confinement is mobilized by pressurizing an 8-in. wide and 4-in.
long FML specimen with an air-inflated bellows via a thin soil layer placed
on both sides of the FML. The resulting influence of this type of confined
test on the stress-strain behavior of geotextiles (particularly the nonwoven
variety) is seen to be very large. Figure 4-47 presents the results of
confined and unconfined stress-strain testing of two geotextiles. Confined
testing was performed with a confining pressure of 100 kN m~2 (14.5 psi).
In general, the stress at failure and the apparent modulus increase, whereas
the strain at failure decreases. The amount depends upon the material type
and the level of confining stress. Work is ongoing as to the behavior of
FMLs under varying confining pressures.
12
10
E
Jl
o
o
Confining
pressure
100
4-^ Unconfined
In-lsolation
10 20 30 40
AXIAL STRAIN ('/.)
pressure
100 kN/m2/ /
10 20 30
AXIAL STRAIN CM
(a)
(b)
Figure 4-47. Confined and unconfined stress-strain testing of two
geotextiles. (Source: McGown et al, 1982, p 797).
Sustained Load (Creep) Behavior of FMLs. Compared with more traditional
materials of construction, polymeric materials have a relatively high tend-
ency to creep under constant load, as indicated in Section 4.2.
Creep testing generally results in one of three different deformation
vs. time response curves. These response curves are shown in Figure 4-48.
4-127
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.o
03
O
"S
D
Figure 4-48.
Time (t)
Types of creep behavior. Curve A describes creep failure.
Curve B shows constant creep after initial deformation by load.
Curve C shows no creep after initial deformation by load.
Since Curve A is in, or leading to, a failure state it is beyond consider-
ation and only curves like B or C are to be considered. The empirical
relationship defined by these two curves is represented by the following
equation:
= e
+ b log t
(4-9)
where
b
t
strain at a future time "t",
initial, or elastic, strain,
experimentally obtained constant, and
service time under consideration.
To simulate the
need to be evaluated
be accomplished using
paragraph except that
creep behavior of an in-service FML, test specimens
under some type of confinement. This confinement can
the same equipment that is described in the previous
a dead load is applied to the specimen. An example of
the unconfined and confined stress-strain testing followed by creep of two
geotextiles is presented in Figure 4-49.
Little work has been done on the creep testing of confined FMLs, but
work has progressed in assessing polymer behavior under constant stress or
constant strain in both the geotextile and geogrid areas (McGown et al, 1982;
Shrestha and Bell, 1982; and Tensar, n.d.).
Shear Strength of FMLs Against Soil. Adequate friction between a soil
and an FML is important in the performance of FML-lined slopes in land
4-128
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30
10
TIME (hours)
001 01 10 10 100 1000
•30
•20
*
Unconfined
In-lsolatiorf
,^ Confining
pressure
100 kN/m2 •
(a)
TIME (hours)
ooi 0.1 10 10 no loco
Unconfined
Confining pressure
100 kN/m2 x
(b)
O \?
Figure 4-49. Confined and unconfined stress-strain testing followed
by creep of two geosynthetics. (Source: McGown et al,
1982, p 795).
storage and disposal facilities. Without adequate friction, there may be
slippage between components of the liner system. A laboratory test for
determining the shear strength of FMLs against different soil types has been
developed (Martin et al, 1984; Koerner et al, 1986). This test is a direct
4-129
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adaptation of a direct shear test commonly used in geotechnical engineering.
Figure 4-50 presents this test schematically. The FML test sample is placed
on a rigid block in the upper or lower half of the shear box. The other half
has soil at the prescribed density and water content. A normal stress is
applied to the system and held constant, after which shear stress is applied
at a uniform deformation rate. Although the test method is still in an ASTM
D35 Subcommittee, the shear deformation rate commonly used is 0.2 ipm.
Figure 4-51a schematically shows the results of testing an FML against a soil
three times with the same deformation rate but with three different normal
stresses. The peak shear stresses resulting from these tests are used to
plot the Mohr Coulomb failure curve of Figure 4-51b. From this curve the
shear strength parameters of adhesion (ca) and FML-to-soil friction angle
(6) can be graphically determined. These values can then be compared to
the shear strength parameters of the soil itself to obtain efficiencies in
the following manner:
EC = (ca/c) x 100, (4-10)
E = (tan 6/tan <(>) x 100, (4-11)
where
Ec = cohesion efficiency,
Eij> = friction angle efficiency,
c = soil cohesion, and
<(> = soil friction angle.
Normal Stress (an)
Shear Stress ( r)
(a) Cohesive Soil Above FML
i
///./.._,,6,.t.On t
(b) Granular Soil Below FML
Figure 4-50. Direct shear test to evaluate FML-against-soil shear strength.
4-130
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a?
55
fe
5
co
55
1
CO
Strain
Normal Stress (an )
(a) Shear stress vs. strain curves
of an FML tested three times with
a single deformation rate and
three different normal stresses,
(b) Mohr-Coulomb failure curve
n
and
Figure 4-51.
Typical direct shear curves and determination of FML-to-soil
friction angle (<5) and adhesion (ca).
Tables 4-28 and 4-29 present some relative values of FMLs versus dif-
ferent soils. It should be noted, however, that the tests must be conducted
for each situation independently with as close of a simulation as possible to
the in situ condition. It should be noted that water content in fine-grained
soils Ts Critically important. For example, an FML which is a secondary
composite liner in a landfill will be in intimate contact with the clay soil
beneath it. The water content of this clay influences the shear strength
parameters greatly. When the clay is placed wet of optimum, very low values
usually result. The long-term situation as the clay changes in water content
is also of interest.
4-131
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TABLE 4-28. FRICTION ANGLE VALUES AND
EFFICIENCIES FOR FMLS TO GRANULAR SOILS
Soil types3
Mica
FML
CSPE
EPDM
HOPE
Concrete
6 E
25°
24°
18°
sand
> %
81
77
56
Ottawa
6 E
21°
29°
18°
sand
:$, %
72
68
61
schist
6
23°
24°
17°
sand
E
-------
TABLE 4-29. SHEAR STRENGTH PARAMETERS OF FMLS TO COHESIVE SOILS AT OPTIMUM WATER CONTENT
Soil No.
^
i— •
oo
00
Description
Soil to soil
FML to soil:
CPE
EPDM
HOPE
PVC
c
9.0
ca
8.0
5.0
5.0
8.5
Ec.X
100
Er. X
89
55
88
94
1 ML-CL
*
38
6
40
33
26
39
Ef. X
100
E4, X
100
83
62
100
Soil No. 2 CL-ML
c
12.0
ca
3.2
5.0
2.0
3.7
EC-*
100
Ec. X
27
42
17
31
*
34
S
24
23
23
23
E,.«
100
E*. X
66
63
63
63
Soil No.
c
20
ca
13.0
8.0
14.0
14.0
Ec. X
100
Ec. X
65
40
70
70
3 CL
+
30
6
17
23
15
16
E,. X
100
Et, X
53
74
46
50
Soil No.
c
25
ca
8.0
7.5
3.0
7.0
Ec. X
100
Ec, X
32
30
12
28
4 SP-CH
+
24
6
23
20
21
24
E,. X
100
E,.l
95
82
86
100
Soil No.
c
28
ca
10.0
9.0
14.0
12.0
EC.X
100
EC.X
36
32
50
43
5 CH-SP
+
22
6
19
18
15
17
E,. X
100
E,, X
85
80
66
76
Note: c and ca are in units of kN/m2, * and 6 are in degrees.
Source: Koerner et al, 1986, p 28.
-------
Depth Within
Channels
Figure 1-52. Schematic view of embedment depth test apparatus.
S
V)
V)
-------
Puncture (Hydrostatic) Resistance of In-Service FMLs. The integrity of
an FML is essential for its functioning properly during service. The FML
may be penetrated or punctured by gradual piercing caused by a protrusion
from the subgrade. The load placed on the FML may cause a hole to form
gradually as the FML bridges a small cavity and hydraulic pressure forces the
liner down into the cavity. The standard tests, including FTMS 101C Methods
2031 and 2065 for puncture resistance and the Mullen hydrostatic test (ASTM
D751) which are discussed in Section 4.2.2.5.2, test only a limited-size
sample. These test conditions do not'simulate the differential stresses of
a larger area FML over an irregular subgrade. Various tests have been
developed which attempt to simulate the performance on an FML which is under
a hydrostatic pressure and which has been placed on an irregular substrate.
The conditions that have been simulated include:
-Bursting over interstitial spaces in a subgrade (Frobel, 1983;
Morrison and Starbuck, 1984; Fayoux and Londiere, 1984; Mitchell and
Cuello, 1986; Frobel et al, 1987).
- Puncture over protrusions (Frobel et al, 1987; Rigo, 1977; Morrison
and Starbuck, 1984; Frobel, 1983).
- Bursting related to settlement of the subgrade (Steffen, 1984).
- Bursting related to damage caused by a load placed on a cover material
over the FML (Fayoux and Loudiere, 1984).
All of these tests use similar testing devices. With the exception of
Steffen (1984) who used only compressed air, a compressed air-on-water
pressurizing system was used to simulate hydrostatic head. Effective
diameter of the test specimens ranged from 8 in. up to 39 inches. Hydro-
static testing has also been used to study the effect of using geotextiles
to protect FMLs (Frobel et al, 1987; Fayoux and Loudiere, 1984). An example
of a hydrostatic testing device is presented in Figure 4-54.
4.2.2.6 Fingerprinting of FMLs—
The fingerprint of an FML is the sum total of its analytical properties
as determined by the tests discussed in Section 4.2.2.5. The data generated
by these tests establish a body of data that can identify the FML. Finger-
printing a polymeric FML at the time of installation can be used:
- To assess the quality of the specific FML being placed at a site.
- To assure the designer/owner/operator that the FML being placed in the
field is equivalent to the FML that was tested in the compatibility
studies, such as EPA Method 9090 liner compatibility test.
- To establish a baseline for assessing the effects of service exposure
on the FML.
4-135
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compressed air
cover
tor-
middle ring ° r
JTL/^
rubber
sealing ring
sealing ring
water layer
sample
sand or gravel
filling
valve
Figure 4-54.
Schematic of hydrostatic test facility. (Source: Geosynthetic
Research Institute, 1987b).
The analyses used in fingerprinting an unexposed FML can be used to analyze
exposed FMLs:
- To identify the FML that was originally installed as a liner, with
respect to the type of FML, its composition, and possibly its actual
source (in cases where there is some question due to lack of adequate
records, etc).
- To determine the effects of exposure on the FML, and thus be able
to estimate the probable service life of the liner under service
conditions.
In selecting specific analyses for fingerprinting an exposed FML to determine
the effects of exposure, it is important to measure critical properties that
may have been affected by exposure, e.g. extractables. However, in selecting
specific test methods for identifying an exposed FML, it is desirable to
select tests that measure characteristics that do not change with exposure.
Examples of such tests include analyses for the inorganic constituents of the
4-136
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compound (e.g. the trace metals residues of the polymerization catalysts) and
the percentage of carbon black; these compositional characteristics probably
do not change with time since these constituents are insoluble. Most of the
other parameters of the analyses will change to a certain degree with aging
and exposure; consequently, care must be taken in interpreting the results of
these analyses when used for identification purposes, though they can be used
as measures of change in the FML.
Haxo (1983) described a general protocol for fingerprinting FMLs. This
protocol is presented schematically in Figure 4-55, with particular refer-
ence to exposed FMLs. Different polymeric FMLs require different finger-
printing procedures. All tests in the protocol are not used on all mate-
rials. For example, the following is a list of potentially useful tests for
fingerprinting PE FMLs:
- Density and specific gravity of compound and resin*.
- Carbon black content by TGA*.
- Percentage crystallinity by DSC*.
- Oxidative induction time (OIT) by high-pressure DSC*.
- Determination of extractables for amount and composition of the
extract which will include stabilizers and soluble additives that are
in the compound.
- GC analysis of the extract to identify stabilizers.
- Ash content and spectographic determination of the ash for trace
metals residues of polymerization catalysts.
- Melt index*.
- Molecular weight distribution by gel permeation chromatography (GPC).
- Infrared analysis of the polymer to determine the type of PE and of
the extract to identify the stabilizers.
It is not necessary to perform all of these analyses to fingerprint and
identify a specific PE FML. Table 4-30 presents the results of fingerprint-
ing two HOPE FMLs using selected analytical tests. These FMLs had been
received at different times, and fingerprinting was performed to demonstrate
that the two FMLs were probably of the same composition. Similar analyses
can be used for fingerprinting various geosynthetics and pipe, particuarly
those based on PE and PB.
*Suggested minimum tests to be performed for fingerprinting purposes, some
of which are incorporated in specifications.
4-137
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HgO + volatle organfcs
Plasticizer
Polymer
Carbon Mack
Ash
FML as received
from service or
test.W0
CaCfe desiccator
4 days, 50° C
Volatile organics
absorbed in
service or test
Dehydrated specimen, W1
Air oven
2 hours, 105° C
Devolatilized specimen, W2
Solvent extraction
Elemental analysis
byAA
Residual solvent
Figure 4-55.
Plan for the analysis of exposed polymeric FMLs. AA is atomic
absorption analysis for metals; GC is gas chromatograph; IR is
infrared; CHONS is the elemental analysis for carbon, hydrogen,
oxygen, nitrogen, and sulfur.
4-138
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TABLE 4-30. COMPARISON OF THE FINGERPRINTS OF
SAMPLES OF TWO POLYETHYLENE FMLS
Property
Thickness, mil
Density of FML, g cur3
Test method
ASTM D1593
ASTM 0792
FML sample
503-1 503-2
75 84
0.948 0.951
Density of the polyethylene
corrected for carbon black
content, g cm-3 ASTM D792 0.933 0.935
Volatiles, % ASTM D3030-84 0.40 0.05
Extractables, %
By methyl ethyl ketone ASTM D3421-75 1.91 2.01
By n-hexane ASTM D3421-75 3.19 3.03
Infrared spectra of extracts
By methyl ethyl ketone ... Spectra match3
By n-hexane ... Spectra match9
GC analysis of extracts
to determine antioxidants ASTM D4275 b c
Thermal gravimetric
analysis (TGA) d
Carbon black, % 3.4 3.5
Ash, % 0.22 0.17
""onset of weight loss, °C 460 465
Tmax rate of loss, "C 490 495
Differential scanning
calorimetry (DSC) ASTM D3417
Sample as received:
Polyethylene crystallim'ty
in sheeting, % 51 49
Crystal Unity in polymer, t 52 50
on:
In cal/g 33.3 31.8
In Joules/g 141.0 134.7
Melting point (nominal), °C 121 120
After quenching from the melt
at 160°C/min:
Crystal Ifnfty, ( 47.5 39.0
AHfusion:
In cal/g
In Joules/g
Melting point, "C
31.0
131.6
120
25.5
108.3
120
aIR spectra of the methyl ethyl ketone and n-hexane extracts were
slightly different.
bldentified antioxidants were dilauryl thiodipropropionate and
4,4'-thiobis (6-tert-butyl o-cresol).
cldentified antioxidants were 2,6-ditert butyl 4-methyl phenol
(BHT), and 4,4'-thiobis (6-tert-butyl cresol).
dThe ca 5 mg samples were heated in a flow of 40 mL/min. nitrogen
from 40° to 110°C at 40°C/minute. The temperature was held at
HO"C for 5 min. and then increased at a rate of 10"C/min to 600°C
and held until no further weight loss was observed. At that time,
oxygen was introduced to burn carbon black and the weight remain-
ing was ash. The weight loss is followed by a first derivative
computer (FDC) which indicates the temperature during maximum
weight loss. The extropolated onset temperature (Tonset) is
determined by constructing a tangent to the post volatilization
weight line and intersecting with the initial constant weight loss
line (Earnest, 1984).
4-139
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Other types of FMLs can be fingerprinted by some of the same methods.
However, due to their differences in composition, both in the polymer and in
their compounds, they require different analytical tests. Suggested analyses
for fingerprinting CSPE FMLs include:
- Density and specific gravity.
- TGA to measure the overall composition with respect to plasticizers
and the type of fillers.
- Elemental analyses to measure chlorine and sulfur contents.
- Extraction and analyses of the extract by IR and GC.
-Ash determination followed by spectographic analysis or atomic
absorption (AA) analysis for the metals that are used in the slow
crosslinking of the CSPE during exposure, e.g. magnesium, zinc, and
lead.
Suggested analyses for fingerprinting PVC and CPE FMLs include:
- Density and specific gravity.
- TGA to measure the overall composition with respect to plasticizers
and the type of fillers.
- Extraction and analysis of the extract by IR, GC, or gas chromato-
graphy/mass spectrography (GC/MS) for identification of the various
plasticizers incorporated in the FML. Many of the plasticizers are
themselves mixtures of a variety of oily liquids.
- Ash and analysis of the ash for trace metals and fillers.
In addition to being based on a single polymer, FML compositions can
also be based on blends of two or more polymers of different compositions.
The fact that the polymer component of an FML is a blend will be apparent in
several of the analyses, e.g. TGA, IR, etc.
4.2.3 Geotextiles
Geotextiles can perform a number of functions and have grown into a
viable industry in their own right. In waste containment practice, however,
their use is primarily in providing a filtration function. This function is
emphasized in this section. This is not to say that strength or modulus is
not important. A weak geotextile can easily intrude into the pore space of a
drainage net or composite rendering its flow significantly less than its
as-manufactured capability. This is discussed later in Section 4.2.6.4. In
addition, geotextiles have also been used to protect FMLs placed in the
field. Various types of geotextiles are illustrated in Figure 4-56.
4-140
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Figure 4-56. Various types of geotextiles.
4.2.3.1 Polymer Types Used in Manufacture--
Geotextiles have been made from many polymer types used for fibers but
currently polypropylene and polyester types prevail. Table 4-31 lists some
advantages and disadvantages-of each polymer. It should be noted that
polyester geotextiles are sensitive to alkaline solutions and wastes. There
have been concerted efforts recently to produce high and medium density
polyethylene goetextiles, which are being aimed directly at the waste con-
tainment applications. These materials are now made in Germany.
4.2.3.2 Geotextile Fibers and Fabrics--
A number of fiber types (monofilament, multifilament, slit film) can be
used to make a variety of fabric types. As can be seen in Figure 4-56, the
fabrics are woven or nonwoven. Furthermore, there is a large variety of
weaving patterns (plain, modified, etc.) and nonwoven manufacturing tech-
niques (heat set, needle punched, resin bonded, etc.) which gives rise to a
wide variety of products. There are probably 1000 different commerically
available geotextiles at the present time (June, 1988). The number of
geotextiles available alone demands that rational design toward selection
of a geotextile must be used. Such a methodology is at the heart of the
"design-by-function" concept.
4.2.3.3 Filtration Principles--
When filtration is the primary function to be achieved, rational design
requires two competing mechanisms to be achieved:
- Adequate flow capability.
4-141
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- Upstream soil particle retention.
Note that these are competing mechanisms where adequate flow requires large
fabric pores and soil particle retention requires small fabric pores. Thus,
knowledge of both the flow regime and soil characteristics are essential for
proper design.
TABLE 4-31. GENERAL COMMENTS ON POLYMERS USED IN
MANUFACTURE OF GEOTEXTILES
Type
Advantages
Disadvantages
Polypropylene (PP)
Polyester (PET)a
Not sensitive to varying pH
Widely used
Relatively low cost
Good temperature stability
Good creep resistance
Goo'd ultraviolet stability
Widely used
Good temperature stability
Somewhat creep sensitive
Poor ultraviolet stability
without carbon black
Some uncertainty in
organic solvents
High alkalinity degrada-
tion (pH > 11) for some
polyesters
Slightly higher cost than
PP
Some uncertainty in
organic solvents
aPolyethylene terephthalate.
4.2.3.3.1 Adequate permittivity—Flow through geotextiles is governed
by its permittivity which is obtained directly from modification of Darcy's
law as follows:
q = M A >
Ah
q - kn — A ,
q
Ah~A '
(4-12)
(4-13)
(4-14)
4-142
-------
where
q = flow rate (ft^ min.)>
i = hydraulic gradient (ft ft"1),
Ah = hydraulic head difference (ft),
A = area of flow (ft2),
kn = permeability normal to the plane of the fabric (ft min.'l),
t = thickness of the fabric (ft), and
fy = permittivity (min.~l).
This value of permittivity is calculated using known or estimated flow rates
and then compared to the actual, or test, value of permittivity to obtain a
flow rate factor of safety (FS) as follows:
FS = *act/*req'd (4-15)
where
*act = actual, or test, value and
^req'd = required, or design, value.
Some actual, or test, values of permittivity of typical commerically avail-
able geotextiles are shown in Table 4-32. Values were obtained in accordance
with ASTM D4491.
TABLE 4-32 TYPICAL PERMITTIVITY AND PERMEABILITY
VALUES OF GEOTEXTILES
Fabric type
Woven monofi lament
Nonwoven needled
Nonwoven heat set
Nonwoven resin bonded
Woven silt film
Permittivity,
sec'1
1000
50
10
1 -
1
- 0.1
- 0.1
- 0.1
0.005
- 0.01
Permeability,
cm sec'l
10
1
0.1
0.05
0.01
- 0.001
- 0.01
- 0.005
- 0.001
- 0.001
4-143
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The value of the resulting FS should be above 10, and even 100 is not
uncommon when considering the potential of long-term clogging.
4.2.3.3.2 Soil retention—The voids in a geotextile should not be too
large since this results in a loss of upstream soil and eventual clogging of
the downstream drainage system. Most soil retention criteria are formed
around the following concept:
°fabric -< * dsoil (4-16)
where
°fabric = an opening size of the fabric (often 095),
dsoil = a particle size of the soil (often dgs), and
A = a value depending on soil density, gradation, fabric-type,
etc.
Betacchi and Cazzuffi (1985) compare a number of criteria; of these, the
criteria described by Carroll (1983) is widely used. This criteria is as
follows:
095 < (2 or 3) d85 (4-17)
where
095 = 95% opening size of the fabric, and
dg5 = particle size, at which 85% of the soil is finer.
4.2.3.4 Long-Term Compatibil ity--
A significant consideration in designing goetextile filters is their
long-term compatibility with the environment that surrounds them (Koerner et
al, in press). For geotextiles in waste containment facilities having design
lifetimes of 30+ years, several potential problems need to be considered:
- Soil particle clogging.
- Mineral clogging, e.g. ocher and carbonates.
- Bi ological clogging.
- Chemical degradation.
- Burial degradation.
- Long-term creep and possible puncturing.
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4.2.3.4.1 Soil clogging—Soil clogging of geotextile filters has been a
topic of considerable past research (Koerner and Ko, 1982). While a precise
formulation of the soil/geotextile combinations that lead to clogging is not
yet available, several guidelines have emerged (Halse et al, 1987). Problem
areas that are known to exist are the following: gap-graded cohesionless
soils under high hydraulic gradients and highly alkaline conditions. Both of
these situations can lead to complete clogging of the geotextile. For a
precise evaluation, however, laboratory testing of the proposed soil and
candidate geotextile is necessary. Two options are available:
- The gradient ratio test (Haliburton and Wood, 1982).
- The long-term flow test (Koerner and Ko, 1982).
For granular soils and woven monofilament geotextiles the short-term gradient
ratio test can be used. For other conditions long-term tests must be per-
formed; these tests can take up to four months to complete, but they are
necessary to determine if a potential clogging problem exists.
4.2.3.4.2 Biological clogging--Only recently has biological clogging of
geotextile filters (and other drainage-related components) been considered.
The concern is that in the aerobic atmosphere that can exist in drain media,
waste-generated bacteria and fungi can grow in the voids of the geotextile,
thus reducing, or even completely blocking, the flow. Biological clogging is
not considered to be a major problem at hazardous or industrial waste sites,
but could be a problem at municipal waste sites where biological stability is
not ensured. Research is just now beginning that focuses on both the type of
microorganisms that might be present and the type of biocide that might be
used to remedy a situation resulting from the growth if it should occur.
4.2.3.4.3 Chemical degradation—As with all synthetic materials used
in a waste containment system, the geotextiles should also be assessed for
chemical compatibility by immersion in a representative sample of the pro-
posed leachate or waste liquid to be contained or in a simulated leachate.
The exposure procedure can be similar to the one described in EPA Method 9090
for exposing FMLs (EPA, 1986). Tests to determine the effects of exposure
should relate to the specific material being tested for compatibility and its
proposed use in the lining system. Assessment of any adverse performance
must be made, but limits are not available. It should be noted, however,
that the inherent variability of nonwoven geotextiles is considerably greater
than that of FMLs. Test tolerances should be viewed in this light.
4.2.3.4.4 Burial degradation--The effects of soil burial on synthetic
polymeric materials has been documented over periods up to about 50 years.
Even though the general types of polymers used in the components used in the
construction of waste storage and disposal facilities have shown little if
any deterioration in soil burial, concern exists about general burial deg-
radation of geotextiles on extended time periods. If deterioration would
occur, it would probably be from a number of causes, e.g. oxidation/reduc-
tion, hydrolysis, etc. Tests to simulate the effects of long-term burial
in a short period of time are not available. What is available, however, are
4-145
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performance records of geotextiles exhumed over periods of 20 or more years.
In general, the performance of geotextiles when buried in soil has been very
good. Burial in a waste environment is unknown. Sampling and testing of
geotextiles recovered after many years of service in various environments are
needed.
4.2.3.5 Other Considerations--
The secondary property that a geotextile filter must have is adequate
strength. This requires one also to consider adequate resistance to long-
term creep. If the geotextile filter is being used over soil the problem is
not too significant because the span from soil particle to soil particle is
often small, and intrusion into the upper pore space is not meaningful. When
the geotextile is used to cover a geonet or geocomposite, however, resistance
to long-term creep must be addressed. While it is possible to provide an
analytic formulation based on the modulus of elasticity and Poisson's ratio
of the particular geotextile, results are best obtained by testing of the
drainage core both with and without the geotextile filter. This type of
testing will be described in the geonet and geocomposite sections.
4.2.4 Geogrids
Geogrids are used to reinforce soils, e.g. on the slopes. Examples
of this type of product are shown in Figure 4-57. They are sometimes used
within landfills to steepen earth slopes or to create embankments used in
subdividing individual cells of a disposal facility. There may be other uses
as well. Geogrids should not be confused with geonets which are used ex-
clusively as drainage cores. Geogrids are described in this section in terms
of the polymers used in their manufacture, the various designs and styles
presently available, selected aspects of soil reinforcement design, and some
long-term considerations.
Figure 4-57. Various types of reinforcement geogrids
4-146
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4.2.4.1 Polymer Types--
Polyethylene, polypropylene and polyester, all of which have good
chemical resistance, have all been used to manufacture geogrids; some
polyesters, as noted in the sections on geotexiles, are sensitive to alkalis.
When used in landfills, the required service life of geogrids is generally
not the usual landfill completion time plus 30 years after closure, but only
the landfill completion time itself, i.e. time to complete the construction
and filling operations only, which involves time frames of approximately 5
years. Thus, all of the above polymers should be adequate.
4.2.4.2 Various Available Styles--
The geogrids that are available differ in the directionality of their
strength, the size and shape of their apertures, and in their node con-
struction. These differences are the resuts of different manufacturing
approaches. Table 4-33 lists various types of geogrids that are currently
available.
TABLE 4-33. CURRENTLY AVAILABLE GEOGRIDS
Product
Tensar
Tensar
ATP
Signode
Signode
Paragrid
Mi rag rid
Polymer
HOPE
PP
HOPE
PET
PET
PET/PP coated
PET/acrylic
coated
Strength
directionality
Uni axial
Biaxial
Uniaxial
Uni axial
Biaxial
Biaxial
Biaxial
Approximate
aperature
size, in.
4 x 1
1.5 x 1.5
4x1
4x2
4x4
6x4
1.5 x 1.5
Node
construction
Uni ti zed
Un i t i zed
Uni ti zed
Ultrasonic
Ultrasonic
Melt-bonded
Entangled by
knitting
The first geogrids available in the USA were manufactured in England
and were subsequently manufactured in the USA. This style of geogrid is
manufactured by punching holes in extruded HOPE sheeting and continuously
tensioning the sheeting so that the holes become elongated ellipses with an
ultimate draw ratio of approximately 8 to 1. The cold-worked longitudinal
ribs are then in a post-yield state, with considerably improved modulus,
4-147
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strength, and stiffness in the direction of elongation. This product is
known as a unidirectional strength geogrid. A second product type is also
available, wherein the draw is in two perpendicular directions, thus achiev-
ing biaxial strength in the resulting product.
Geogrids are also made by overlapping transverse and longitudinal strips
of high strength polymers and joining them at their intersections, or nodes.
The Signode product is made of high tenacity polyester strips that are
ultrasonically bonded at their nodes. Also available is the Paragrid product
which consists of high tenacity polyester fibers encased within a polypropyl-
ene sheath. These ribs are then melt-bonded at their nodes to form the
junction of transverse and longitudinal ribs.
A third approach to geogrid manufacture consists of entangling poly-
ester yarns at the nodes, thereby forming a grid structure. This type of
geogrid is manufactured under the name Miragrid. Several other companies are
considering variations of this manufacturing approach.
It is important to note in Table 4-33 the type of node construction.
Since stress must be transferred from the transverse ribs (where it bears
against the adjacent soil) to the longitudinal ribs (where the stress is
initially applied), the node strength is critically important. In this
regard, the unitized nodes impart essentially 100% of the rib strength, the
ultrasonic and entangled nodes somewhat less, and the melt-bonded nodes
considerably less.
4.2.4.3 Long-Term Considerations--
Because of the types of applications in which geogrids are used, long-
term considerations for geogrids are of less concern than they are for
other types of geosynthetics used in constructing waste containment units.
Most of the above-mentioned polymers should be sufficiently durable, and
creep is not a problem once the facility is filled. For other potential
applications, this may not be the case, and the entire range of long-term
considerations must be considered (Koerner et al, in press).
4.2.5 Geonets
Geonets are grid-like polymeric products used as in-plane drainage
systems. Various types of geonets that are presently available are il-
lustrated in Figure 4-58. Geonets should not be confused with geogrids,
since the tensile strength of geonets is quite low. Consequently, they
should not be used for soil reinforcement purposes. As geonets are used
exclusively for in-plane drainage, they always act with geotextiles, FMLs, or
other materials on their upper and lower surfaces. For example, a geonet can
be placed between two FMLs, as in a secondary leachate collection system
(leak-detection network), or between a geotextile filter and an FML, as in a
primary leachate collection system.
This section reviews the various types of polymers used in manufactur-
ing geonets, elements of geonet drainage design, and some long-term con-
siderations.
4-148
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4.2.5.1 Polymer Types--
Most polymers currently used to manufacture geonets are polyethylene
of either medium- or high-density types. Polypropylene has also been used,
though quite rarely. The major variation in manufacturing polyethylene
geonets is whether or not a foaming agent has been added to the polymer mix
during formation. This foaming agent expands into small gas-filled closed
cells within the solidified rib material forming a porous structure. The
cells are in the order of a micron in size and are closed and connected.
This type of geonet, in contrast to a solid rib geonet, is referred to as a
foamed geonet. Under long-term load, the latter geonet may lose the gas in
the cells by permeation resulting in partial collapse of the net.
Figure 4-58. Various types of drainage geonets.
4.2.5.2 Manufacturing and Types of Geonets--
Most geonets are made by forcing the molten polymer through counter
rotating slots in an extruder. This produces a grid of bonded and adjacent
ribs at acute angles to one another. Before and during cooling, the grid is
forced over a tapered mandrel which opens up the acute angles between the
ribs to form the desired aperture size. Final rib angles are at 60° to 70°
to one another. The rib cross sections are either square or rectangular.
The deeper the rib size, the thicker the geonet and the greater its drainage
capability. The bond between ribs where they cross over is completely
polymeric. By virtue of the processing, however, the rib crossovers are
usually not vertically aligned, giving rise to a "lay-over" tendency of
ribs at high normal stresses.
4-149
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While the above-described manufacturing process for geonets is the
commonly employed one, other variations are also possible. The manufacturing
of these systems run the gamut of polymer processing and are beyond the scope
of this document. Table 4-34 lists commonly available geonets used in drain-
age systems and their properties.
4.2.5.3 Drainage Design--
The design of a drainage geonet can follow two paths, both of which
are related by Darcy's law of flow. These are flow rate or transmissivity
(Koerner, 1986). The following formulation shows this relationship:
q = kpi A , (4-18)
Ah
q = k (W x t) , (4-19)
Ah x W
q = (kpt) —j-— , (4-20)
let 9 = kpt , (4-21)
'« « •£? • (4-22)
where
0 = transmissivity (ft2 min.'1),
q = flow rate (ft3 min."1),
kp = planar coefficient of permeability (ft min.'1),
i = hydraulic gradient (ft ft'1),
A = Area of flow (ft2),
t = thickness (ft),
L = length (ft),
Ah = hydraulic head difference forcing flow (ft), and
W = width (ft).
4-150
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TABLE 4-34. AVAILABLE GEONETS FOR DRAINAGE PURPOSES
Manufacturer
Tensar
Tensar
Tensar
Poly-Net
Poly-Net
Poly-Net
Poly-Net
Low Bros
Low Bros
Low Bros
Conwed
Conwed
Conwed
Conwed
Conwed
Tenax
Gundle
Type
DN1
DN2
DNS
PN1000
PN2000
PN3000
PN4000
Lotrak 8
Lotrak 30
Lotrak 70
XB8110
XB8210
XB8310
XB8315
XB8410
CE
Gundnet
Polymer
PE
PE
PE
PE
PE
PE
PE
PE
PE
PE
PE
PE
PE
PE
PE
PE
PE
Specific
gravity
0.928
0.928
0.928
0.9365
0.9365
0.9365
0.9365
• • •
• • •
• • *
0.936
0.936
0.936
0.936
0.936
• • •
0.925
Style
Extruded ribs
Extruded ribs
Extruded ribs
Foamed and extruded ribs
Extruded ribs
Extruded ribs
Foamed and extruded ribs
Extruded mesh
Extruded mesh
Extruded mesh
Formed and extruded ribs
Extruded ribs
Extruded ribs
Extruded ribs
Foamed and extruded ribs
Extruded ribs
Extruded ribs
Thickness,
in.
0.25
0.20
0.15
0.25
0.16
0.20
0.30
0.12
0.20
0.29
0.25
0.16
0.20
0.20
0.30
0.20
0.16
Aperature
size, in.
0.3 x 0.3
0.3 x 0.3
0.3 x 0.3
0.3 x 0.3
0.35 x 0.35
0.3 x 0.4
0.25 x 0.25
0.3 x 0.3
1.2 x 1.2
2.8 x 2.8
0.3 x 0.3
0.35 x 0.35
0.3 x 0.4
0.3 x 0.3
0.25 x 0.25
0.3 x 0.25
0.3 x 0.3
-------
Using either transmissivity (o) or flow rate (q), design proceeds using a
factor of safety concept, i.e.:
eact or test
Veq'd or design
or
FS=e7—r: — , (4-23)
Qact or test
FS=- . (4-24)
9req d or design
The denominator of these equations is the required or design value which is
obtained by calculations, regulations, experience, or judgment. Examples
are available (Richardson and Koerner, 1987). The numerator of the equations
is the actual or test value of the candidate geonet. It is usually evaluated
using ASTM D4716-87 test procedure. This test uses flat plates above and
below the net and is for a relatively short duration, i.e. 15 minutes dwell
time for the applied normal load and 15 minutes for the flow measurements.
Thus, it can be considered to be an index test resulting in "upper bound"
flow values vs. the j_n situ (or allowable) values. An example of flow
behavior for a solid rib geonet is presented in Figure 4-59a. These results
show that there is an initial decrease in flow with applied pressure but,
once the system "slack" is eliminated, the flow is stabilized. The next
possible event in the flow behavior is where the ribs "lay over" on one
another, but for this product "lay over" only occurs at normal pressures over
556 psi. Figure 4-59b shows the behavior of a foamed rib geonet where the
flow is generally quite higher than with solid ribs but a flow reduction is
also seen indicative of a compression of the pores within the rib structure.
Of importance, however, is that flow rates are seen to decrease greatly
around 100 psi signifying "lay over" of the ribs with respect to one another.
It was mentioned that these flow values represent the upper limits of
the actual performance behavior of the geonet. Field performance flow values
will be equal to or less than these test values because of the intrusion of
the geotextile or FML into the core space. When pressurizing soil against
the geotextile or FML covering the geonet, intrusion occurs which decreases
flow. This intrusion is not evaluated in tests when rigid plates are used.
The amount of intrusion is site-specific depending upon the following:
- Applied normal pressure.
- Size and type of soil particles causing intrusion.
- Rigidity (stiffness) of adjacent materials.
- Thickness of adjacent materials.
- Spacing of ribs.
- Size of ribs.
4-152
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150 200 250 300 350 400 450 500 550
100
Normal Stress, psi
(a) SOLID RIB GEONET
Q.
O>
£
TO
cc
I
50
100
Normal Stress, psi
(b) FOAMED RIB GEONET
150
200
Figure 4-59. Flow rate behavior of geonets at different gradients (i),
4-153
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This intrusion can be illustrated by infilling a quicksetting elastomer into
the core space under simulated operating conditions. Photographs illustrat-
ing the intrusion of FMLs into geonets resulting from the application of
pressure are presented in Figure 4-60 for both solid rib and foamed rib
goenets. The ASTM flow test procedure can be modified to account for these
conditions and the reduced value of flow evaluated and quantified. Unless
this simulation is performed, quite high factor of safety values should
be used when calculations are based on rigid plate test results.
4.2.5.4 Long-Term Considerations—
There are a series of considerations regarding the functioning of
geonet drains over the design lifetime of the facility. This time frame
includes the 30-year postclosure period as well as the operating lifetime.
These considerations are material effects, creep of the geonet, creep of
adjacent materials, chemical effects and biological effects. Each will be
discussed briefly.
4.2.5.4.1 Material effects—Solid rib constructed geonets appear to
be quite stable under load. However, there has been concern expressed over
the foamed rib geonets. The foaming agents that are used result in nitrogen
being the gas holding the pores open. As is characteristic of closed foam
products under external pressure, the nitrogen will diffuse with time through
the polymer surrounding it, causing a collapse of the pores, loss of geonet
thickness, and proportionate loss of flow capability. The situation should
be investigated and evaluated.
4.2.5.4.2 Creep of net-- Under high normal pressures the net itself
can deform and cause reduced flow. This is best combated by using high
factors of safety on flow and against rib "lay over." Absorption of organics
that have permeated the FML will aggravate the tendency toward creep.
4.2.5.4.3 Creep of adjacent materials—Figure 4-60 illustrates the
short term, or elastic, intrusion of adjacent geosynthetics into the geonet
apertures. Extended time periods will tend to cause creep deformations of
the adjacent geotextile or FMLs which will further reduce flow. In the
absence of quantitative data, high factors of safety on the strength (or
better, the modulus) of the adjacent materials is necessary. Creep of
adjacent materials should not be dismissed as a trivial problem; it is very
difficult to treat analytically and requires further experimentation and
evaluation.
4.2.5.4.4 Chemical effects—Long-term exposure to waste streams could
deteriorate the rib strength of the geonets, which must be assessed in im-
mersion tests similar to those used to assess FMLs. The recommended test
assessing the possible loss in strength of geonets after immersion is the
CBR strength (puncture) test (Murphy and Koerner, for publication in 1988).
4.2.5.4.5 Biological effects—Though the polymers used in the manu-
facture of geonets are not metabolized by microorganisms, fungi and other
growth can attach to the polymer surface. Thus, if microorganisms find their
4-154
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f>
c:
o
O)
en
o
•I—
l/l
s_
QJ
\—
•
O
I
O)
en
4-155
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way into geonets, the drainage capability can be reduced. To what degree
obviously depends upon the extent and type of bacterial and fungal growth.
It is a situation currently being evaluated in hazardous and municipal
landfill leachates under both aerobic and anaerobic conditions. This study
is also evaluating the types of biocide that might be used to remedy the
situation.
4.2.6 Geocomposites
Geocomposites is a term loosely used to identify a wide range of compo-
site materials that consist of two or more geosynthetics. The function
of a geocomposite could be any of those listed in Table 4-1 (Koerner, 1986);
the function of drainage is emphasized in this section.
Drainage geocomposites are sometimes used as primary leachate collection
subsystems with a geotextile filter attached, or as surface water collectors
in a landfill closure. An overlap with geonets will be noted, but these
drainage geocomposites are quite different in their performance, behavior,
and variations. Figure 4-61 shows various types of geocomposites that are
currently available. This section discusses the type of polymers used to
manufacture geocomposites, the different types of geocomposites currently
available, drainage design, and considerations about long-term usage.
Figure 4-61. Various types of drainage geocomposites,
4.2.6.1 Polymer Types--
A variety of polymers has been used to manufacture geocomposite drainage
compositions, including polystyrene, PP, PVC, and PE. Perhaps the most
4-156
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common is high impact polystyrene since the largest market for these systems
seems to be transportation-related projects where the liquid being drained is
usually groundwater. Where potential chemical interactions might occur, as
in waste containment applications, PE might be the preferred polymeric
material.
4.2.6.2 Types of Geocomposites--
A great variety of manufactured products and resulting types of drainage
geocomposites is available. The drainage cores themselves take the shape of
columns, piers, cuspations, dimples, etc. Manufacturing itself covers many
variations of polymer processing. A recent characterization by Kraemer
and Smith (1986) is presented in Table 4-35. Review of this table suggests
that both mechanical and hydraulic properties will vary widely from product
to product. It is simply not possible to have an "or-equal" situation in
considering these materials. Their specification will require a specified
flow rate or transmissivity, at a given applied normal pressure, at a given
hydraulic gradient.
4.2.6.3 Drainage Design—
Drainage design using geocomposites follows that described in the
section on geonets. A resulting factor of safety for flow must be formulated
using the actual test value as numerator and the required design value as
the denominator. When considering the primary leachate collection system,
flow rates can be quite high especially during seasons of high precipitation.
Thus, drainage capability of primary leachate collection systems is con-
siderably higher than the capacity of secondary leachate collection systems.
Richardson and Koerner (1987) offer some guidance as to quantities.
The actual flow capability of the geocomposite can be evaluated using
ASTM Test Method D4716. Results from such tests are presented in Figure
4-62. Note that, in comparison to geonets, very high flow rates are avail-
able with these systems. However, it should also be noted that the breakdown
(collapse) pressure of the geocomposites is much less than with geonets.
This latter feature has severe implications when considering long-term
creep.
As with geonets, flow values resulting from tests between rigid plates
are maximum field service values. Intrusion into the core space by the
geotextile filter above the flow columns, and (to a lesser extent) FML
intrusion from below, will reduce flow considerably. Figures 4-63 and 4-64
illustrate this feature for both of the products shown in Figure 4-62. Note
that the collapse of the cores at the high pressure is clearly evident and
must be designed against. Thus, in addition to the flow design, one must be
concerned to design against collapse failure as well which requires a high
factor of safety.
4-157
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4.2.6.4 Long-Term Considerations —
Long-term effects on geocomposites being used as drains in waste ap-
plications are similar to those discussed in the section and geonets. Thus
material, chemical, and biological concerns must be considered. Again, as
with geonets, creep behavior must be assessed. Since many of these systems
are built up with hollow cores or cuspations and have aperture spaces greater
than geonets, both axial creep of core and creep intrusion of the adjacent
geotextile are of great concern. High factors of safety in both cases are
warranted.
TABLE 4-35. VARIOUS TYPES OF DRAINAGE GEOCOMPOSITES
Product
Ameri drain™ 360
Eljen Drainage System
Enkadrain 9010
Enkadrain 9120
GEOTECH™ Drainage Board
HITEK" 8
HITEK1" Cordrain™
HITEK"1 Stripdrain"1
Hyd raway "
Miradrain™ 4000
Miradrain1" 6000
Nudrain1" A
Nudrain1" B
Perma drain
Stripdrain 75
Stripdrain 150
Tensar DN1
Type
Channels
Waffle
Fibers
Fibers
Beads
Waffle
Waffle
Waffle
Columns
Waffle
Dimpled sheet
Waffle
Waffle
Waffle
Waffle
Waffle
Grid
Material3
HOPE
HIPS
Nylon 6
Nylon 6
EP
HOPE
HOPE
HOPE
LDPE
HIPS
HIPS
ABS
PP
HOPE
HOPE
HOPE
LDPE
Compression
strength, psi
28
30
7
16
6
70
40
20
60
30
75
40
15
28
35
20
• • •
aHDPE = high-density polyethylene; HIPS = high-impact polystyrene;
EP = expanded polystyrene; LDPE = low-density polyethylene;
ABS = acrylonitrile-butadiene-styrene; PP = polypropylene.
Source: Kraemer and Smith, 1986.
4-158
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6 - 8 10
Applied Pressure, 103 psf
(a) GEOCOMPOSITE CORE WITH HIGH COLUMNS
1.0
2 4 6 8 10 12 14
Applied Pressure, 103 psf
(b) GEOCOMPOSITE CORE WITH EXTRUDED CUSPATIONS
16
Figure 4-62. Flow rate behavior of geocomposite cores between rigid plates
in short-term test; "i" is equal to the hydraulic gradient.
4-159
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Figure 4-63. Sequence of photographs showing the intrusion of a filter
geotextile into drainage core flow space of a drainage compo-
site with high columns when under various loads. The photo-
graphs are of a series of test assemblies after the setting of
an epoxy resin which had been introduced in assembly after each
had been under the indicated load for a few minutes. Note that
the columns were beginning to collapse at 30 psi load and had
col lapsed at 60 psi.
The situation is considerably different when using drainage geocompo-
sites in caps or closure systems, in which case the liquid is usually water
from rainfall or snowmelt and the normal stresses are quite low. Thus, high
factors of safety can easily be obtained.
4.2.7 Pipes and Fittings
Pipes are used in waste containment in leachate collection and leak-
detection systems and in gas venting applications. The pipes used in these
applications need to be either perforated or slotted. Pipes will also be
used for inlet and outlet structures to convey wastes into and out of the
system and in monitoring systems. In all of these applications, penetrations
through the liner may be required; current thinking is to avoid, whenever
possible, penetration of the liner. For example, waste liquids can be
carried into and out of the system over the berm.
4-160
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30 to/in2 (207 kPa)
SAND WITH RESIN
GEOTEXTILE
CUSPS
DRAINAGE SPACE FILLED
WITH CURED EPOXY
60lb/in2(4l3 kPa)
SAND WITH RESIN
GEOTEXTILE
CUSPS
DRAINAGE SPACE FILLED
WITH CURED EPOXY
>,***» *
SAND WITH RESIN
90 b/in 2(620 kPa)
GEOTEXTILE
COLLAPSED CUSPS
Figure 4-64.
Sequence of photographs showing the intrusion of a filter geo-
textile into drainage core flow space of a drainage composite
with extruded cuspations when under various loads for short
periods of time. Photographs were taken of the cross sections
of a series of test assemblies after the setting of an epoxy
resin which had been introduced in assembly after it had been
under the indicated load for a few minutes. Note that the
cusps had collapsed under 90 psi load with almost complete loss
of drainage space.
Thermoplastic pipe materials, such as PVC and HOPE, are preferred over
nonplastic pipe materials for leachate collection and drainage above a liner
because of the wide range of chemical resistance of the thermoplastics,
particularly to inorganic chemicals. Typically, for use beneath the liner,
design engineers have specified a wider range of materials (E. C. Jordan Co.,
1984). Polymeric pipe materials that may be appropriate for use in below
liner leachate collection systems and their properties are presented in Table
4-36. The structural properties of pipes range considerably. Flexible and
semiflexible pipes derive structural stability from bedding materials, while
rigid pipes require less structural support.
4-161
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TABLE 4-36. PLASTIC PIPE APPROPRIATE FOR USE IN LEACHATE COLLECTION AND LEAK DETECTION SYSTEMS
Ol
ro
Type
Poly vinyl
chloride
(PVC)
Polyethylene
high -density
(HOPE):
1. Smooth
2. Corrugated
Acrylonitrile
butadiene
styrene (ABS)
Fiberglass
Factory
Characteristics perforation
Flexible. Joints: A3
solvent weld,
threaded, mechanical
flanged, push-on with
elastomeric seal.
Flexible. Joints: NAb
butt welds.
Flexible. Joints: A
push-on. Fittings
available.
Seim-rigid, solid wall. A
Joints: solvent weld.
Fittings available.
Rigid, flexible, A
available as filament
wound and contact
molded pipe. Joints:
solvent weld,
flanged, treaded.
Fittings available.
Compatibility
Resistant
Most inorganic
solutions
Inorganic
reactants ,
aqueous solu-
tions of in-
organic salts
and bases
Same as above.
chemical
Susceptible
Organic
solvents
Organic
solvents,
concen-
trated
oxidizing
agents
Resistant to a braod range
of chemicals and
see manufacturers
mendations.
Highly corrosion
See manufacturers
mendations.
wastes;
recom-
resistant.
recora-
Construction
considerations
Lightweight and easily
handled by one person.
Pipe bedding crucial
to load resistance.
Control of trench grade
is critical.
Mechanical handling
required. Bedding
crucial to load re-
sistance. Control of
trench grade not
critical.
Easily handled by one
person. Bedding
critical to load re-
sistance. Control of
trench grade not
critical.
Easily handled by one
person. Control of
trench grade is
critical.
Easily handled by one
person; care should be
used to avoid damage.
Bedding critical to
load resistance; con-
trol of trench grade
crucial.
Strength
consideration
Available in many
strength classes.
Pressure/nonpres-
ure applications.
Available for
pressure and non-
pressure uses.
Nonpressures
uses. Mostly use
in shallow cover
applications.
Available in two
strengths. Pres-
sure and non-
pressure uses.
Pressure, non-
pressure uses.
Many strength
classes
available.
aA - Available.
>>NA - Not Available.
Source: E. C. Jordan Co., 1984, p 17.
-------
Bass et al (1984) summarized the factors affecting pipe stability for
above-liner leachate collection systems as:
- Vertical loading of waste and operating equipment.
- Perforations.
- Deflection.
- Buckling.
- Compressive strength.
- Chemical resistance to the waste.
- Natural pipe deterioration.
All are of equal concern in below-liner systems. Pipes in leachate collec-
tion systems are generally bedded and backfilled with drain rock. When
placed in trenches, the trench containing both the backfill bedding and
the pipe is usually wrapped with a geotextile. Design issues relating to
determining flow capacity and spacing of the pipe are found in Appendix I.
Pipe durability can be assessed in terms of service life and resistance
to deflection and failure under load. The service life of piping materials
in waste containment situations cannot be verified based on field data
because of the relatively recent usage of these materials in this mode. In
order to meet the service life requirements of the total facility, pipe
materials should be evaluated for chemical compatibility and should be
resistant to excessive deflection and failure, which will ultimately serve to
clog the drainage system. Fracture during installation, particularly in the
case of rigid wall pipe, should be guarded against, as should the application
of live loads during construction. The behavior of pipe under the combined
influences of load and waste exposure must be evaluated, when potential
incompatibility exists between the pipe materials and the waste.
In above-liner leachate collection systems, piping materials are
required to conduct fluid under heavy loads for many years. Since thermo-
plastic pipes are generally used in above-liner leachate collection systems,
potential negative effects resulting from swelling or softening caused by
waste materials must be considered. If the waste material to be handled
contains organic materials, then chemical resistance of the pipe to the
specific waste needs to be evaluated. In general, the chemical compatibility
of HOPE pipe can be considered to be equivalent to that of HOPE FMLs. PVC
polymers, which are used unplasticized in pipes, may be more susceptible to
organics than HOPE.
4-163
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A wide variety of test methods for characterizing plastic pipe has been
published by ASTM, the Plastic Pipe Institute, the Gas Research Institute,
and the National Sanitation Foundation. Table 4-37 lists some of the ASTM
test methods.
TABLE 4-37. METHODS FOR EVALUATING HOPE PIPE
Property Test Method
Specific gravity ASTM D1505
Tensile strength ASTM D638
Modulus of elasticity ASTM D638
External loading properties ASTM D2412
Coefficient of linear expansion ASTM D696
Thermal conductivity ASTM C177
Hydrostatic design basis ASTM D2837
Hydrostatic design stress ASTM D2837
4.3 ADMIXED LINER MATERIALS
A variety of admixed or formed-in-place liners have been successfully
used in the impoundment and conveyance of water. The materials used in these
liners include asphalt concrete, soil cement, and bentonite-sand mixtures.
All are hard surface, rigid or semirigid materials which are formed in place
from raw materials brought to the site. They are composed of a mixture of
granular and cementitious materials compacted to form a uniform dense mass,
and are porous by nature.
Even though liners constructed from admixed materials have demonstrated
durability in the impoundment and conveyance of water, considerably less
information is available on the use of some of the admixes for the contain-
ment of brines and other waste materials. Materials of this type have
undergone pilot- and bench-scale exposure testing in contact with municipal
solid waste leachate, and have undergone pilot and bench-scale limited
exposure testing with hazardous wastes (Haxo et al, 1982; Haxo et al, 1985).
Admix liner materials composed of soil cement and two polymer-modified
bentonite-sand mixtures are currently undergoing exposure testing with wastes
from coal-fired electric power plants in a research project for the Electric
Power Research Institute (Haxo et al, 1987a; Haxo and Nelson, 1986).
4-164
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This section discusses asphalt concrete and soil cement. Bentonite-
sand liners are discussed in the TRD on soil prepared by Research Triangle
Institute (Goldman et al, 1987).
4.3.1 Hydraulic Asphalt Concrete
Hydraulic asphalt concrete (HAC) is a hot-mixed and hot-laid control-
led mixture of asphalt cement and graded aggregates. The material is hard
surfaced and resistant to traffic and impact forces as well as to acids
and aging, particularly in the absence of light and air. The use of these
materials for water storage has been documented (Hickey, 1971b).
Hydraulic asphalt concrete liners in hydraulic construction and waste
containment applications require high quality dense-graded aggregates to
create a nearly voidless mix ensuring low permeability. In addition, the
aggregate must be compatible with the waste liquid. In comparison to paving
asphalt concretes, hydraulic asphalt concretes have a higher content of
mineral filler and a higher asphalt cement content (usually 6.5 to 9.5 parts
per 100 parts dry aggregate) to reduce voids. The asphalt used in hydraulic
asphalt concrete is usually a low penetration grade (40-50 or 60-70) since
these harder asphalts are better suited for liners than softer paving grade
asphalts (Asphalt Institute, 1981). The final HAC product is harder, denser,
and more homogeneous than paving asphalts.
4.3.1.1 Permeability of Hydraulic Asphalt Concrete--
Permeability is the most important property in selecting asphalt liner
materials. Initial permeability is influenced by voids ratio, percent
asphalt, density at compaction and liner thickness. Hydraulic asphalt con-
crete can be compacted to have a permeability coefficient less than 1 x 10"7
cm s~l. The liner should be compacted to at least 97% of the density
obtained by the Marshall method and have a voids content less than 4%
(Asphalt Institute, 1976; Asphalt Institute, 1981). Hinkle (1976) found that
a voids content of less than 2.5% produced a permeability of less than 1 x
10~9 cm s~l, as is shown in Table 4-38. Styron and Fry (1979) used an
11% asphalt content compacted to a 2-in. thickness to achieve permeability
coefficients in test cells less than 1 x 10~9 cm s~l. Two-inch thick HAC
liners with asphalt contents from 7 to 11% have been common field practice
for the Bureau of Reclamation in water storage ponds for many years (Asphalt
Institute, 1966). Haxo et al (1982) used a 9% asphalt concrete for MSW
leachate exposure studies, but after one year of exposure determined that a
thickness greater than 4 in. may be necessary to contain wastes, due to
potential inhomogeneities in the admixture resulting from inadequate mixing
or compaction. This conclusion is borne out by Hinkle (1976) in a study for
California Edison, which demonstrated that an optional compacted thickness
for a liner containing primary water was 4 in. and that this thickness would
be achieved by compacting two layers in separate 2-in. thick lifts.
4-165
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TABLE 4-38. PERMEABILITY OF ASPHALT CONCRETE TO WATER
en
Asphalt,
7.5
7.5
7.5
7.5
7.75
7.75
8.0
8.0
8.0
8.5
8.5
8.5
8.5
8.5
8.5
8.5
8.5
8.75
8.75
8.75
8.75
Compac-
tion9,
99.2
98.0
93.8
91.4
96.0
99.0
93.2
93.0
98.7
90.6
94.4
94.0
96.0
96.0
97.0
98.0
98.0
99.0
99.8
99.5
98.0
Voids,
2.8
3.9
8.0
10.4
6.9
2.9
8.0
8.4
2.6
9.5
6.0
6.2
4.2
4.2
3.2
2.1
2.6
2.3
1.7
2.0
3.6
Specific
gravity
2.248
2.223
2.128
2.072
2.147
2.240
2.115
2.107
2.240
2.067
2.147
2.144
2.189
2.189
2.313
2.236
2.224
2.226
2.240
2.232
2.197
Unit
weight
140.
138.
132.
129.
134.
139.
132.
131.
139.
129.
134.
133.
136.
136.
138.
139.
138.
138.
139.
139.
137.
3
7
8
1
0
8
0
5
8
0
0
8
6
6
0
5
8
9
8
3
1
Maximum
specific
gravity
2.313
2.313
2.313
2.313
2.306
2.306
2.299
2.299
2.299
2.285
2.285
2.285
2.285
2.285
2.285
2.285
2.285
2.279
2.279
2.279
2.279
Permeability
constant,
nrillidarcys
7.6
1.6
1.05
1.53
1.97
9.7
1.3
1.3
<1.9
3.0
5.2
4.3
1.3
8.2
<4.8
<3.8
<5.5 x
<1.6
<9.6 x
<8.0 x
<1.2
x 10-7
x 10-7
x 10-4
x ID'3
x 10-6
x 10-7
x 10-4
x 10-3
x 10-9
x 10-7
x 10-8
x 10-5
x 10-5
x ID'6
x 10-9
x 10-9
10-10
x 10-9
10-10
10-10
x 10-9
Coefficient of
permeability
cm/sec
7.9
1.7
1.09
1.58
2.04
1.0
1.31
1.3
<2
3.1
5.4
4.4
1.4
8.48
<5
<4
<5.7 x
<1.88
<9.28 x
<7.79 x
<1.21
x 10-7
x 10-7
x ID'4
x 10-3
x 10-6
x 10-6
x ID'4
x ID'3
x 10-9
x 10-7
x 10-8
x lO-5
x ID-5
x 10-6
x 10-9
x 10-9
10-10
x 10-9
10-10
10-10
x 10-9
ft/yr
0.82
0.18
112
1630
2.1
1.0
136
1340
<0.002
0.32
0.056
46
14
8.8
<0.005
<0.004
<0.0005b
<0.0016b
<0.0009b
<0.0007b
<0.00lb
aBased on 35 blows Marshall = 100%.
^Samples still on permeability apparatus at time of Hinkle's publication.
Source: Hinkle, 1976.
-------
4.3.1.2 Durability of Asphalt Concrete--
Once a material of sufficiently low permeability has been achieved, the
second property of concern is durability. Carefully designed and installed
facilities for water storage have lasted for more than a quarter of a century
in this country. Bureau of Reclamation and Department of Interior experience
with this material for water storage and conveyance and for desalinization
ponds indicates that it is resistant to light vehicular traffic, freeze/thaw
cycles (U.S. Department of Interior, 1971), and the destructive forces of
wave action. Its semirigid nature imparts enough flexibility to conform to
slight deformations in the subgrade and to resist low-level seismic activity.
It maintains integrity well on side slopes and resists creep and slippage.
Asphalt concrete is subject to the following failure mechanisms:
Mechanical: Failure from severe deformation in the subgrade.
Failure at construction joints.
Chemical: Incompatibility of asphalt with wastes.
Incompatibility of aggregate with wastes.
Excessive absorption of water causing swelling
and sloughing.
Environmental: Transverse-cracking due to thermal cycling.
Puncture of liner by roots and weeds.
Ultraviolet degradation of the asphalt and certain
susceptible aggregates.
Oxidative hardening of air exposed liners.
The durability of asphalt concrete liners in waste containment applica-
tions is less well characterized; available information is based on labora-
tory and pilot-scale field studies as well as limited field experience. The
major factor determining durability of asphalt liner materials in these
applications is the compatibility of the waste with the asphalt as well as
with the mineral aggregate components in the asphalt concrete (Kays, 1977).
Of major importance in considering asphaltic materials for lining of waste
containment facilities is the sensitivity of asphalt to many organic species.
4.3.1.3 Evaluation of Asphaltic Liner Materials--
Procedures for evaluating the properties of asphalts are listed in Table
4-39. These test procedures can be used to evaluate the material properties
of the asphalt mix components before and after exposure to waste materials
and for quality control of mix design.
4-167
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TABLE 4-39. APPLICABLE METHODS FOR TESTING OF HYDRAULIC ASPHALT CONCRETE
Property Test method
Water permeability Back-pressure permeameter
(Vallerga and Hicks, 1968)
Density and voids ASTM D1184 and D2041
Water swell California Division of Highways 305
Compressive strength ASTM D1074
Asphalt content ASTM D1856
Penetration of asphalt ASTM D5
Viscosity of asphalt, sliding plate California Division of Highways 348
Sieve analysis of the aggregate ASTM C136 and C117
Source: Haxo et al, 1985.
4.3.1.4 Installation Characteristics—
Hydraulic asphalt concrete is applied as hot-mixed concrete, in-place,
using spreaders or slip-form pavers in 10- to 15-ft widths and compacted to
the desired density using a vibrator, tamper, roller, or screed. Temperature
requirements for the hot-mixes range from 400° to 500°F.
4.3.2 Soil Cement
Soil cement consists of a compacted mixture of selected in-place soils,
Portland cement, and water. As the portland cement hydrates, the mixture
becomes a hard, low-strength portland cement concrete which has greater
stability than untreated soil alone can attain. The permeability of soil
cement varies with the grain size of the natural soil: the more granular the
soil, the higher the permeability. Since the cement component of the soil-
cement admix is a minor ingredient by volume, particular attention must be
paid to the soil component. Any nonorganic soil with less than 50% silt and
clay is suitable for soil cement. A high clay content reduces the efficiency
of the soil in producing a low permeability layer, by impairing the formation
of homogeneous cemented materials. Best results for water retention are
obtained when the cement is mixed with a well-graded sandy soil, with 5 to
35% passing the No. 200 (75ym) sieve (PCA, 1978). Cement contents may vary
from 7 to 10%, depending upon the porosity of the soil materials used.
Generally, the second most important concern in designing soil-cement liners
of low permeability is density at compaction, since the higher the density of
the soil cement, the lower its permeability. Compactibility in turn depends
upon the moisture content of the soil-cement mixture.
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Chemical sealants, including epoxy asphalt and epoxy coal tars are often
applied over soil cements to decrease permeability, and may be sprayed on or
applied in place. The sealing effect of such materials is limited to the
upper centimeters of the liner. The compatibility of these materials with
the waste to be contained needs to be evaluated separately from evaluation of
the soil-cement admixed materials.
Three major concerns in using soil-cement liners are their tendency to
develop wet-dry and freeze-thaw cracks leading to seepage, their incom-
patibility with waste species arising from their cement content, and their
brittleness leading to deformation-induced cracking and to leakage.
Soil-cement liners have been recently discussed by Adaska (1985) at
a symposium on impermeable barriers for soil and rock. This paper reviews
basic information on soil cement as a liner material and describes research
on permeability and compatibility testing. The design, construction, and
performance of some unique soil-cement-lined projects were presented, as
well as information on a new composite soil-cement/FML liner system.
4.3.2.1 Permeability of Soil Cement--
As with all liner materials, permeability is the property of primary
significance in selecting liner materials constructed of soil cement.
Whenever soil cement is used as a liner in such hydraulic structures as
dams, canals, etc., the main emphasis is on reducing the erosivity of the
soil, i.e. to increase hydromechanical strength rather than to produce a
blanket of low permeability. There have been few studies performed to design
soil cements that have low permeabilities (less than 10~8 cm s~l) compared
with studies of mixes designed for compressive strength.
Literature on the permeability characteristics of soil cement is am-
biguous, and does not indicate unequivocally that the addition of cement to
soil makes it less permeable. The chemical composition of portland cement
does not provide an answer to this question. Indeed, the cement should
release to the soil solution calcium ions from the free lime and gypsum
present in the cement. The calcium ions should aid soil aggregation and,
thus, increase the median pore size which should result in a soil matrix with
a greater permeability. Although few studies on design of low permeability
soil-cement liners have been conducted, experience indicates that a fine-
grained soil can be used to produce a permeability of 1 x 10~6 cm s~l
(Styron and Fry, 1979; Stewart, 1978).
There are five fundamental requirements which are essential to achievii
permeability (less than 10"? cm s~l) in soil-cement liners used in
e environment. They are:
- The soil material needs to be of sufficiently low porosity to achieve
a liner of low permeability.
- The moisture content required to attain maximum density needs to be
used.
4-169
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- The minimum cement content needed to reinforce the soil to specific-
ation must be used.
- The soil cement must be compacted to the design density.
- The constituent materials of the soil cement must be compatible with
the wastes to be contained.
Examples of water permeability of soil-cement specimens using various
soil types and cement and water contents are presented in Table 4-40. The
results indicate that permeabilities as low as 4 x 10'8 cm s"1 can be
achieved in laboratory and pilot-scale experiments using graywacke fines
(Haxo et al, 1985). Thus, it may be possible to achieve soil-cement admixes
with lower permeabilities than has been accepted in the field, pending
further exploratory research and field experience. Specification of design
criteria for acceptable permeability performance and careful selection and
preliminary testing of the soil and cement materials to select the optimum
design mix are essential to achieve acceptable permeability levels for the
design life of the liner.
4.3.2.2 Durability of Soil Cement--
Soil cement has been used for many years for paving applications, for
slopes and embankments, and for water storage and conveyance. Applications
in the last 25 years have included lining of municipal and industrial waste-
water storage and treatment lagoons and ash settlement ponds (PCA, 1981).
Soil cement is hard-surfaced, resistant to impact forces, and provides a
durable working surface for reclaiming materials from evaporation and settle-
ment ponds. The manufacture of erosion resistant, durable soil-cement
materials have been studied for many years, and design factors for selection
of these properties are well understood. The aging characteristics of
soil-cement are good, especially under conditions where wet-dry and freeze-
thaw cycles are minimal.
Soil-cement admixes are subject to the following failure mechanisms:
Mechanical: Failure from shrinkage and cracking.
Failure at construction joints.
Failure from deformation in the subgrade soil and
erosion on slopes and sidewalls.
Chemical:
Incompatibility of soil with waste.
Incompatibility of cement with waste.
Incompatibility of sealing or coating
material with waste.
4-170
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Environmental: Freeze-thaw and wet-dry cycling leading to cracking
and failure.
Degradation of surface by wave action, particularly
on slopes and embankments.
It should be noted that research by the Portland Cement Association (Wilder,
1976) indicates that soil cement made with fine-grained silty soil is less
erosion resistant than soil cement based on coarser materials.
TABLE 4-40. WATER PERMEABILITY OF SOIL-CEMENT SPECIMENS^
Soil
Tennis court clay
Tennis court clay
Tennis court clay
"Mud jack ing" clay
"Mudjacking" clay
"Mud jack ing" clay
Graywacke fines
Graywacke fines
Graywacke fines
Core from specimen
compacted in spacer
in eel 1 base
Type V
cement,
parts per
100 g
dry soil
8
10
12
8
10
12
10
12
IOC
12
Water,
parts per
100 g
dry soil
10
10
10
12
12
12
13
12
12
13.4
Coefficient of permeability
cm s~l
1.6 x 10-6
1.3 x 10-6
5.1 x 10-6
3.4 x 10-6
5.3 x 10-6
6.5 x 10-6
1.9 x 10-6
1.5 x 10-7b
2.9 x 10~7d
4.0 x 10-?e
5.7 x 10-8
in. yr'l
20
16
63
42
66
81
24
1.9b
3.6
5.0
0.71
aExcept where otherwise noted, permeabilities determined in a back-pres-
sure permeameter with a confining pressure of 2.0 atm for all specimens
except those made with "mudjacking" clay (1.3 atm confining pressure), a
back pressure of 1.0 atm, and a gradient of approximately 25.
^Average of measurements with back-pressures ranging from 1.0 to 3.0 atm.
cRice hull ash cement (an acid-resistant pozzolanic cement).
^Average of measurement of back-pressures ranging from 2.0 to 4.0 atm.
eRepeat with back pressure of 1.0 atm.
Source: Haxo et al, 1985, p 46.
4-171
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It can be expected that a soil-cement mixture will perform differently
and show variations in durability at each exposure zone: submerged liner,
waste/air interface, and exposed slope. Variations in cement content and
soil-grain size may be required to meet the durability requirements of each
zone.
4.3.2.3 Evaulation of Soil-Cement Materials —
The composition of soil varies considerably, and these variations affect
the manner in which the soil reacts when combined with portland cement and
water. The presence of a waste material adds an additional set of variables.
The way a given soil reacts with cement is determined by laboratory tests
made on mixtures of cement with the soil; cement content directly affects
moisture requirements, due to the hydration requirements of the cement.
Table 4-41 presents a list of test methods that may be applied in the
design, pre-construction, and construction phases of soil-cement liner
evaluation, design and construction.
TABLE 4-41. APPLICABLE TEST METHODS FOR ANALYSIS
OF SOIL-CEMENT LINER MATERIALS
Property Soil cement
Water permeability Triaxial permeameter9
with back-pressure
saturation
Density and voids ASTM D558
Water swell ASTM D559
Expansion/contraction ASTM D560
Compressive strength ASTM D1633
Compaction Percent proctor density
Sieve analysis ASTM D422
Freeze-thaw ...
Permeabilities determined in a back-pressure triaxial
permeameter (Vallerga and Hicks, 1968).
Standard laboratory tests should be performed to determine the cement
content, optimum moisture content, and maximum density of the soil-cement
mixture necessary to meet the performance requirements of the liner. These
test must be performed using the specific on-site soils, borrow materials, or
4-172
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combinations thereof, that are actually being considered for use in the final
liner product. This information is required to predict performance as well
as to select the most economical combination of materials. Optimum moisture
content and maximum density for molding laboratory specimens are determined
in accordance with ASTM D558. Test specimens are then molded at several
cement contents and subjected to wet-dry ASTM D559 tests and freeze-thaw.
For liner applications, samples of the same formulations that are under-
going evaluation using these standardized test methods must be molded into
briquets, cured, and subjected to permeability tests such as with the
back-pressure triaxial permeameter (Vallerga and Hicks, 1968).
4.4 SPRAYED-ON FMLS
FMLs can be formed in the field by spraying materials (e.g. air-blown
and emulsified asphalts) onto a prepared soil surface on which a geotextile
may or may not have been placed. The sprayed-on liquid solidifies in place
to form a continuous seam-free membrane. Such liners have been used in
canals, small reservoirs and ponds for water control and for storage of brine
solutions. Water storage applications have used air-blown asphalt; however,
FMs from asphalt blends containing additives of elastomeric polymers and
fillers are being used in solar ponds for containment of brines, and are
being promoted by manufacturers as suitable materials for waste storage
applications in the mining industry (Chambers, 1989).
Many sprayed-on liners have a soil cover placed on top of them. Ponds
in a recycling system may not be covered because a material would contaminate
the liquid being contained. Uncovered sprayed-on FMLs are sometimes painted
with white latex paint.
Though sprayed-on FMLs are seam-free, bubbles and pinholes, which are
extremely difficult to detect, may form during field installation causing
serious difficulties at a late date. The proper preparation of the surface
to be sprayed is important. The asphaltic materials are thermoplastic and
of low molecular weight, and will react adversely with many wastes. However,
in carefully controlled conditions, and when protected from mechanical damage
and ultraviolet degradation, they can be used to form a serviceable liner for
brines and many inorganic solutions.
Materials discussed in this section will include air-blown asphalt,
emulsified asphalt, styrene-butadiene rubber (SBR) asphalt, and urethane-
modified asphalt.
4.4.1 Air-Blown Asphalt FMLs
Catalytically-blown asphalt FMLs are the most commonly used spray-
on FMLs, and have been used by the Bureau of Reclamation for many years for
water conveyance and storage (Bureau of Reclamation, 1963). The asphalts
used in making these FMLs have high softening point temperatures and are
manufactured by blowing air through the molten asphalt at temperatures in
excess of 500°F in the presence of a catalyst such as phosphorous pentoxide
or ferric chloride. To fabricate the FML, the asphalt is sprayed on a
4-173
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prepared soil surface at 400°F at a pressure of 50 psi through a slot-type
nozzle and at a rate of 1.5 gal yd~2 (Bureau of Reclamation, 1963, pp
80-81). The finished liner is usually 0.25 in. thick (Bureau of Reclamation,
1963, p 79) and is formed by two or more passes of the spray device and
overlapping sections by one or two feet (Clark and Moyer, 1974). It can be
placed during cold or wet weather, in large quantities, by mobile equipment
(Bureau of Reclamation, 1963, p 10). Sprayed-on FMLs retain their tough
flexible qualities for extended periods of time when properly covered and
protected from mechanical damage (Asphalt Institute, 1976). The acutal
placing of the earth covers on a sprayed-on FML may cause some damage to its
integrity.
Studies have shown that the addition of 3-5% rubber improves the prop-
erties of the asphalt by inducing greater resistance to flow, increased
elasticity and toughness, decreased brittleness at low temperatures, and
greater resistance to aging (Chan et al, 1978, p 17). Two types of rubber-
modified asphalt are discussed below.
Bituminous seals are used on asphalt concrete, portland cement concrete,
or soil-cement liners to close pores, thus improving water-proofing or when
there may be a reaction between the stored liquid and the liner. The two
types of seals usually applied are:
o
- An asphalt cement sprayed over the surface about one qt yd to form
an FML about 0.04-in. thick.
- An asphalt mastic containing 25 - 50% asphalt cement, the rest being
a mineral filler, squeegeed on at 5 - 10 Ib yd~2.
Sprayed-on asphaltic FMLs are usually installed on a subgrade which has
been dragged and rolled to obtain a smooth surface. If there is an excessive
number of irregular rocks and angular pieces, a fine sand or soil "padding"
is necessary for good FML support (Bureau of Reclamation, 1963, p 81). The
asphalt may also be sprayed onto a geotextile placed on the soil surface
to give protection against puncture.
A blend consisting of cationic asphalt emulsion, white gasoline, and
water was applied as a temporary sealer at a rate of 0.3 gal yd"2 to a
prewetted surface. The rate of application of the asphalt emulsion component
was 0.09 gal yd"2. Assuming a 60% asphalt content, the rate of application
was 7.20 oz yd"2 or 0.8 oz ft"2. Penetration into the surface varied from
3/16 to 3/8 inch. Based on laboratory tests, the application rate was far
less than that required to provide satisfactory penetration and sealing.
However, for this installation, only a temporary reduction of water loss
during the initial operation period of the lagoon was required because sewage
was expected eventually to seal the lagoon (Bureau of Reclamation, 1963, p
115). For this application in the field the asphalt emulsion was considered
to have performed satisfactorily.
A proprietary liquid cutback asphalt formulated for deep penetration was
applied over natural-on-site soil at a rate of 2 gal yd"2. Assuming a 50%
4-174
-------
concentration of asphalt in the cutback, this rate of application is equiva-
lent to 16.5 oz yd~2 or 1.8 oz ft~2. The seepage rate was reduced from 15.9
ft3 ft-2 yp-1 for the untreated soil to 6.14 ft3 ft"2 yr"1 for the treated
soil (Day, 1970, p 21).
In another example, cationic asphalt emulsion formed a low permeability
seal at the soil interface through the attraction of the positively charged
asphalt droplets to the negatively charged soil particles as the emulsion
penetrates the substrate. In this case, the asphalt emulsion was applied at
the rate of 1.05 gal yd~2, which is equivalent to about 15.6 oz ft"2 asphalt.
This product has been used mainly in reservoirs and ponds (Wren, 1973).
Field data on a hot-applied asphalt FML in a canal lateral was obtained
after 11 years of service (Geier, 1968). The seepage rate at this time was
0.08 ft3 ft"2 d~l. The seepage rate prior to placement of the liner was
9.9 ft3 ft"2 d~l. Ninety percent of the aging occurred during the first
four years of service. A poor correlation was found between the 14-day
laboratory aging test at 60°C and actual field aging. Geier (1968, p 3)
concluded that, if properly applied and covered, a buried hot-applied
asphalt sprayed-on canal liner should last beyond 12 years.
Except for their poor resistance to hydrocarbon solvents, oils, and
fats, the chemical resistance of asphaltic FMLs is, in general, good.
Asphaltic FMLs are resistant to methyl and ethyl alcohols, gylcols, mineral
acids other than nitric acid (at moderate temperatures and concentrations),
mineral salts, alkalis to about 30% concentration, and corrosive gases such
as H2S and S02- Asphaltic FMLs exhibited variable to poor performance
when exposed to hydrogen halide vapors, but have very low permeability to
water (National Association of Corrosion Eng., 1966).
4.4.2 Emulsified Asphalt FMLs
Emulsions of asphalt in water can be sprayed at ambient temperatures
(above freezing) to form continuous FMLs of asphalt after breaking of the
emulsion and evaporation of the water. These FMLs are less tough and have
lower softening points than FMLs made with hot-applied catalytically-blown
asphalt. Toughness and dimensional stability can be achieved by spraying
asphalt emulsionss onto a supporting fabric. Fabrics of woven jute, woven or
nonwoven glass fiber, and nonwoven synthetic fibers have been used with
various anionic or cationic asphalt emulsions to form linings for ponds and
canals, and as reinforcing patches under asphalt concrete overlays to prevent
"reflection" of cracks in the old pavement beneath. Seams in the supporting
fabric are often sewn with portable sewing machines after the fabric is
placed (Phillips Petroleum, 1973).
4.4.3 Styrene-Butadiene Rubber (SBR)/Asphalt FMLs
Styrene-butadiene rubbers have been used in recent years as additives
to catalytically-blown asphalt. Thermoplastic SBR intended for hot-melts
has some unique properties that enchance its usefulness for certain liner
4-175
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applications. At room temperatures it behaves like crosslinked elastomeric
rubber; when heated above 212°F (the glass transition temperature of the
domains which behaves like crosslinked polystyrene), it behaves like an
uncured elastomer. Chambers (1980) reports that, by mixing thermoplastic SBR
polymers with prime grade asphalts, it is possible to achieve a thermoplastic
material which behaves like an elastomeric polymer. The resultant FML is
inert to inorganic acids, bases, and salts and has low permeability to water.
The useful temperature range (-40° to 180°F) of the SBR/asphalt is greater
than that of common asphalt grades (ca 40° to 120°F). Chambers reports a
case history in which an SBR/asphalt FML was used in solar evaporation ponds
containing magnesium chloride, applied over a geotextile-covered earthen base
(Chambers and Farr, 1984).
4.4.4 Urethane-Modified Asphalt FMLs
A urethane-modified asphalt FML system is being marketed. It is
generally spray applied, but may be squeegeed onto a prepared surface. A
premix is combined with the activator, and sprayed on at a rate of two
gallons per minute, covering about eight square yards per minute. The
fabricated membrane is generally recommended to have a thickness of 50 mils,
usually obtained by applying one coat at a rate of 0.28 gal yd~2 on hori-
zontal surfaces or two coats on vertical surfaces. The second coat may be
applied about 15 minutes after the first coat. The liner must cure for 24
hours before being put into service. This system has good UV stability and
low temperature ductility, eliminating the need for a soil cover in most
cases. The liner system is limited to a maximum of 140°F continuous exposure
and is not recommended for prolonged exposure to hydrocarbon or organic
solvents. It should be applied only to properly prepared surfaces. The
surface must be clean and dry. Porous surfaces should be filled. Generally,
a primer and a bonding agent are applied before the modified asphalt is
applied. The procedures for several base surfaces and the necessary pre-
cautions are provided by the manufacturer (Chevron, 1980).
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CHAPTER 5
EXPOSURE OF POLYMERIC FMLS AND RELATED MATERIALS
OF CONSTRUCTION IN SIMULATED-SERVICE ENVIRONMENTS
5.1 INTRODUCTION
This chapter focuses on the simulated-service testing of FMLs and
other materials of construction used in constructing lining systems for
waste containment units, including polymeric materials used in constructing
leachate collection and removal systems (LCRSs) and admix lining materials.
The results of laboratory, bench-scale, and pilot-scale research performed
to evaluate these materials under conditions that simulate service environ-
ments in waste containment units are reported. Much of this research was
initiated in the early 1970's and was conducted with the materials that
were available at that time to assess their usefulness in the construction or
environmentally-sound waste storage and disposal facilities. Many of these
materials were tested on the basis of their prior use in lining water con-
veyance and storage facilities.
As background to discussing tests of FMLs and ancillary materials under
simulated-service conditions, the environments that FMLs and other materials
may encounter in actual waste storage or disposal units are described. These
environmental conditions either have been observed directly or are considered
highly probable. The types of containment units discussed include municipal
solid waste (MSW) landfills, surface impoundments, hazardous waste landfills,
waste piles, heap leach pads, secondary containment facilities, and tailings
ponds.
The types of stresses encountered by materials in these environments
include chemical, mechanical, and biological stresses. Since the polymers
used in manufacturing polymeric materials of construction for waste contain-
ment units are essentially not biodegradable, the effect of chemical,
mechanical, and combined chemical and mechanical stresses on FMLs and other
materials of construction are of particular interest. Initial research
evaluating lining materials in waste environments focused particularly on the
effects of chemical stresses.
This chapter presents representative data on the performance of polymer-
ic FMLs and admix and sprayed-on liner materials exposed in simulated-ser-
vice tests. These materials were exposed to a variety of test liquids and
actual waste liquids, including MSW leachate and hazardous, toxic, and
5-1
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industrial wastes, under a variety of simulated-service conditions, including
exposure in one-sided exposure cells (to simulate exposure at the bottom of a
containment unit), two-sided immersion tests, and roof tubs (to simulate ex-
posure in a surface impoundment. Data on changes in physical and analytical
properties of these liner materials after long-term exposure to the waste
liquids and/or after long-term weathering, as well as test data on changes in
permeability after exposure, are presented. The potential effects of these
environmental conditions on FML durability and long-term performance are
discussed. This chapter also presents data on the mechanical interaction of
materials (e.g. liners and geonets) within the same system, and the effects
of biaxial stresses on liner materials exposed to waste liquids or other
aggressive environmental conditions. Available data on ancillary materials
in simulated service environments are presented.
One objective of these studies was to develop criteria to establish and
predict compatibility and long-term serviceability of a given material in a
given service environment. The first step in developing such criteria
involves establishing a correlation between the measured properties and the
performance of a given material in a given service environment. Given this
correlation between properties and performance, the rate of change in the
properties of a material in a given environment could then be used to
estimate the service life of that material. For example, in the case of many
rubber products produced and used over the years, a series of laboratory-
measured properties have been found to relate directly to the functioning and
service life. It has been found from experience that when certain values are
reached or when certain changes have occurred, the product becomes no longer
functional for the purpose for which it was designed. For instance, a 50%
loss on aging in the values of such properties as tensile strength and
elongation have indicated a failure of many products; also, in some ap-
plications an increase of 15 hardness points or a doubling of modulus has
also been indicative of failure in the performance of that product. Such
properties as these may have used directly in the designing and compounding
of these products to meet performance needs or they may correlate with other
properties that relate directly to a performance requirement. At this point
in the technology of waste storage and disposal facilities and the materials
that are used in their construction, the correlation between properties and
changes in their measured values and performance requirements has not been
developed.
It must be recognized that waste containment technology is a compara-
tively recent development and is still in the process of development. The
synthetic polymers, such as those used in the manufacture of FMLs and other
geosynthetics, have only been available for about 60 years. Furthermore,
these materials have been used in the manufacture of FMs for only 35 years
(and less for other geosynthetics), and FMLs have only been used in waste
containment for approximately 20 years. However, even though much proprie-
tary data may exist, the information on performance in the available liter-
ature is limited and generally poorly documented. Consequently, the data
based on experience which can be used for establishing correlations with
5-2
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laboratory results are limited. At this time criteria which can be applied
to laboratory and small-scale testing to indicate the compatibility and the
long-term performance of various materials in waste containment environments
still need to be established.
The data reported in this chapter include data on materials that are no
longer available or no longer being used for the specific purposes for which
they were evaluated. However, these data are included because they describe
the approach that was taken in assessing the materials. These data can be
used to indicate the pitfalls in materials that may be under development.
Also, they indicate the limitations of many of the materials which may be
considered for applications that approximate the applications for which these
materials were tested. In view of the fact many of the initial containment
units were lined with these materials and are still in existence, their per-
formance can be observed. The results may also be useful in developing cor-
relations between laboratory and bench-scale testing and field performance.
5.2 ENVIRONMENTS IN TREATMENT, STORAGE, AND DISPOSAL FACILITIES
(TSDFS) ENCOUNTERED BY FMLS AND ANCILLARY MATERIALS DURING
CONSTRUCTION AND SERVICE
5.2.1 Introduction
The environment in which an FML liner material is exposed during
construction and service will ultimately determine its service life, that is,
how long it will perform its designed functions. Table 4-20 enumerates
environmental factors that can affect the durability of polymeric FMLs and
ancillary materials. Environmental factors during installation and in
specific applications are discussed in the following sections. The types
of facilities that are discussed include the following:
- MSW landfills.
- Surface impoundments.
- Hazardous waste landfills.
- Waste piles.
- Heap leach pads.
- Secondary containment facilities.
- Tailings ponds.
5.2.2 Environments Encountered During Construction
The conditions that an FML encounters from the time of manufacture
and fabrication into panels through installation to the final acceptance by
an owner of the lined storage or disposal facility require the FML to have
a substantial degree of ruggedness. Most of the FMLs and the ancillary
5-3
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materials have relatively little structural strength. They must be protected
in various ways from mechanical and other enviromental damage during fabri-
cation, shipping, field construction, and inspection. Table 5-1 lists some
of the significant conditions that an FML and other construction materials
may encounter in the construction of waste storage and disposal facilities.
In assessing FMLs and the other materials for lining TDSF facilities, these
environmental conditions must be recognized in testing and evaluating FMLs
and their seam systems.
TABLE 5-1. ENVIRONMENTAL CONDITIONS ENCOUNTERED BY FMLS AND
ANCILLARY MATERIALS PRIOR TO AND DURING CONSTRUCTION
OF HASTE STORAGE AND DISPOSAL FACILITIES
- Temperature extremes; low temperatures can cause embrittlement, and
high temperatures can cause softening, reduced strength, and shrinkage
of some FMLs and expansion of others.
- Temperature variation during a day and for very short intervals
(clear to cloudy skies).
- Wind and wind variation over short time periods.
- Humidity variation during the day.
- Much of the construction must be done on slopes, an important factor
in seaming.
- Workers' traffic during seaming operation and liner inspection.
- Light equipment traffic which might puncture, tear, or abrade the
FML surface. No equipment should be allowed on the FML surface after
installation has been completed.
- Dust and possibly gravel which might affect seam strength.
- Impact damage from dropped tools.
- Stretching and tensioning during FML placement.
- UV light and oxygen which might affect the surface of some FMLs before
being covered; both UV light and oxygen can also degrade geotextiles
and some geonets and geogrids.
- Dimensional change, including shrinkage due to heat and relaxation of
residual strain from manufacture and thermal expansion.
- Soil covering operations.
5-4
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5.2.3 MSW Landfills
During service in a lined MSW landfill, the components of the liner and
leachate colection systems can encounter a variety of conditions in different
parts of the landfill ranging from the exposure environment for the cover
and venting system above the MSW to the environment in the leachate drainage
and liner system below the waste. Of particular importance are the liner
drainage and sump systems which are underload and may be in continual contact
with the leachate. A schematic of a closed landfill is presented in Figure
5-1.
Exposure conditions for an FML in an MSW landfill are represented
schematically in Figure 5-2. Some of the conditions at the base of such a
landfill should have no adverse effect on life expectancy of a polymeric FML
and other polymeric materials, whereas other conditions could be quite
deleterious. Some of the important conditions that exist at the bottom of an
MSW landfill in the proximity of the liner system and may influence its
service life are presented in Table 5-2.
The environment that a cover liner system is exposed to differs from
that at the bottom of a landfill. The principal function of a landfill
cover is to prevent the intrusion of water into the landfill and thus mini-
mize the production of leachate. The cover system as described in Chapter 7
includes an FML, layers of geotextiles, geonets, and possibly plastic pipes
for venting the gases generated within the landfill. A soil layer of two or
more feet in thickness can be placed on the FML and planted with grass and
shallow-root plants. The FML would prevent escape of gases which affect
plant growth. The load on the FML in the cover system would not be great;
however, the coefficient of friction between the soil and the FML would be a
significant factor, as a heavy rain could result in slippage of the heavy wet
soil on the FML surface. As MSW tends to consolidate unevenly with time,
strains in the FML and other components of the cover system could result and
cause breaks in the FML.
5.2.4 Surface Impoundments
The environmental conditions encountered by FMLs and other construction
materials in surface impoundments contrast greatly with those encountered in
an MSW landfill or in a water reservoir. Figure 5-3 schematically presents
the environmental conditions encountered by an uncovered FML in a service
impoundment. Depending on the waste or liquid being impounded, these condi-
tions can pose a much greater test of the durability of the materials. The
principal difficulties arise in the highly aggressive nature of some of the
wastes to be contained (e.g. in hazardous waste surface impoundments) and
the stringent requirements to prevent transport of waste constituents out of
the impoundment.
Environmental conditions that could be encountered by FMLs in service in
surface impoundments are listed in Tables 5-3 through 5-5 by type of exposure
within an impoundment. These tables describe the effect that particular
5-5
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Leachate Collection
O-)
Filter Layers
Soil Layer
Soil Cover
Membrane Liner
Drainage Layer
Seepage Drain
Anchor
Drainage Layer
Clay Base
Drain Pipes
Membrane Liner
Sump Pump
Figure 5-1. Schematic of a closed landfill with bottom and cover liners of polymeric
FMLs. Bottom liner consists of a single composite liner.
-------
environmental conditions can have on FMLs and ancillary materials. These
three types of exposure are:
- Exposure to weathering only (Table 5-3).
- Exposure at the air-waste liquid interface (Table 5-4).
- Exposure to waste liquid only (Table 5-5).
It should be noted that the design of the surface impoundment will depend on
the type of waste to be contained, i.e. whether or not the type of waste to
be contained is considered hazardous, etc. Figure 5-4 presents a schematic
drawing of an FML/composite double liner system for a surface impoundment for
storage of hazardous wastes or hazardous materials. This design shows the
leachate drainage or leak detection system that is required by the Hazardous
and Solid Waste Amendments of 1984 (EPA, 1984).
Leachate Overburden
S~
"Intermediate cover
Leachate
drain
to sump
Porous soil cover
FML
Graded compacted
clean soil
Conditions
Anchor
• Moist - leachate flowing
• Anaerobic
• Cool-10-20°C
• Dark - no UV
• Slightly acidic leachate
• Few % organics & salts
• Burden of waste
Figure 5-2. Schematic of a lined MSW landfill
and some of the environmental
(Source: Haxo, 1976).
showing basic components
conditions that exist.
5.._2_._5_ Hazardous Waste_ Landfj 1Js
The conditions that FMLs and other construction materials may encounter
in service in hazardous waste landfills are a combination of many of the
conditions that are encountered in MSW landfills and hazardous waste surface
impoundments. Figure 5-1 schematically illustrates the principal features of
a closed landfill including the FML bottom and cover liners. Figure 5-5
schematically represents a bottom double-liner system for a hazardous waste
landfill. This figure presents the basic requirements of a double liner,
showing the arrangements for drainage above the liner and the drainage and
leak detection system below the liner. Figure 5-6 is a schematic profile
of an FML composite double-liner system for a hazardous waste landfill; the
dimensions and specifications presently recommended by the EPA for each
5-7
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TABLE 5-2. ENVIRONMENTAL CONDITIONS ENCOUNTERED BY LINER
SYSTEMS DURING SERVICE IN AN MSW LANDFILL
Placement on a prepared surface, i.e. either a geotextile or a soil surface
which has been graded to allow drainage, has been compacted, and is free of
rocks, stumps, etc.
Anaerobic conditions. In an anaerobic environment, the lack of oxygen
can essentially eliminate oxidative degradation of the materials and
greatly reduce biodegradation by microorganisms; however, some designs for
drainage and leak-detection systems may allow air into a liner system.
No light; the absence of light removes a significant cause of polymer
degradation.
Generally wet-humid conditions, particularly if leachate is being generated
regularly, that could result in the leaching of ingredients, such as plas-
ticizers, from the FML.
Temperatures ranging from 40° to 70°F normally, although high temperatures
can be generated within the fill if aerobic decomposition takes place.
Generally slightly acidic conditions from the leachate due to presence of
organic acids formed in the degradation of the MSW.
High concentration of ions in the leachate that will probably have little
effect on FMLs, but may affect the soil below it if the liner is breached.
Considerable dissolved organic constituents in the leachate which may swell
and degrade some FMLs.
Only modest head pressure, since drainage through porous soil or geo-
synthetics above the FML is designed to take place continually.
Overburden pressure up to more than 100 psi on the FML and the leachate
collection and removal system. Overburden pressure can range from 10 to
more than 100 psi depending on the depth of the fill and the cover system.
High overburden pressure may cause damage to the FML if the soil below it
is rough and may pose severe conditions in the leachate collection and
leak-detection systems, particularly if the materials used are sensitive to
constituents in the leachate. For example, the collapse of drainage pipe
above an FML would not only reduce leachate collection, but could also
result in puncturing of the FML. If the pipe is below the FML, a collapse
could result in localized subsidence that could cause a breach in the FML.
The presence of gases (i.e. carbon dioxide and methane) generated in the
anaerobic decomposition of the refuse. The carbon dioxide will probably be
dissolved in the leachate and contribute to its acidity and may cause
mineralization of the soil in the area of the liner and potential clogging
of the drainage system.
5-8
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component are shown (EPA, 1985). These requirements are discussed in more
detail in Chapter 7. Some of the major conditions that exist in a hazardous
waste landfill and differ from the conditions in a MSW landfill and surface
impoundment are discussed in the following sections.
\\-L7
lnlet
Drain
Monitoring system
.•."•'••:.'Q '•/.
Membrane liner
Sludge
Sand bed
Figure 5-3. Environmental conditions encountered by an uncovered FML in a
surface impoundment.
The organic constituents that are present in a hazardous waste landfill
may be more likely to partition to polymeric materials, such as an FML,
than the organic constituents of the leachate from an MSW. Many of the
organics are volatile and can migrate throughout a hazardous waste landfill
and be absorbed by polymeric materials that are not in direct contact with
the leachate. These organics can permeate the FML and be absorbed by ancil-
lary materials such as geotextiles and geonets. Depending on the organic,
this absorption can soften geonets and thus, in conjunction with the over-
burden placed on a drainage system, can reduce the drainage capacity of a
system that depends on geonets as the drainage medium.
In contrast to an MSW landfill, a hazardous waste landfill is probably
aerobic, which means that microbial action could proceed if the constituents
of the waste do not sterilize the microbes. Microbial action would aid in
the biodegradation of the contents of the landfill, but also may cause fungal
growth and potential clogging of the drainage system.
The hazardous waste will probably not generate the amount of gases that
are generated by MSW. Nevertheless, the volatile organics in the hazardous
waste landfill may need to be controlled as they can permeate the cover liner
and may affect plant growth on the cover. Also, hazardous wastes, if proper-
ly placed with a minimum amount of voids in a landfill, will not consolidate
as much as MSW does; consequently, the strains that might develop in a final
cover system placed on a hazardous waste landfill could be less than those
that develop in a cover for an MSW Landfill.
5-9
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TABLE 5-3. ENVIRONMENTAL CONDITIONS POTENTIALLY ENCOUNTERED
BY POLYMERIC FMLS IN WEATHER EXPOSURE IN SURFACE IMPOUNDMENTS
Condition
Potential effect on FMLs
Presence of air/oxygen
Ozone
Sunlight
High humidity/rain
Elevated temperatures:
Short-term
Long-term
Low temperatures
Wind
Mechanical stress
Fluctuating temperature
(diurnal, clear to cloudy)
Animals
Rain
Ice
Soil cover
Oxidation
Stiffening
Reduction of mechanical strength
Cracking of some FMLs at points of strain
Degradation of polymer:
UV - Stiffening and cracking
IR - High membrane temperature
Cross!inking of some FMLs
Water absorption, leaching of compounding
ingredients
Softening
Reduction of mechanical strength
Stiffening and loss of plasticizer
Acceleration of other forms of degradation
Possible embrittlement
Movement of the liner on the slopes
Stiffening and loss of plasticizer
Flexing and mechanical damage due to wave
action on the FML, particularly if the
large dimension is oriented with the
prevail ing winds
Cracking or tearing
Variation in strain in the FML being
installed
Complications in seaming operations
Punctures, gnawing of holes
Slipping of soil cover on the FML
surface
Puncture of some FflLs
Protects FML from UV light but may slip
on liner and pull liner down
5-10
-------
TABLE 5-4. ENVIRONMENTAL CONDITIONS POTENTIALLY
ENCOUNTERED BY POLYMERIC FMLS AT THE AIR-WASTE LIQUID
INTERFACE IN SURFACE IMPOUNDMENTS
Condition
Potential effect on FMLs
Intermittent exposure
to weather and waste
liquids
Presence of oily layer
or slicks on the
surface of the liquid
Wind and waves
Biological growth on
the surface of the FML
Acceleration of degradation of FML
Swelling of FML; softening of FML
Flexing and mechanical damage
Evaporation of plasticizers and
antidegradents
Damage to underlying earthwork
Surface damage due to adhesion of
the growth and cracking after
growth dries out
5.2.6 Waste Piles
Waste piles are noncontainerized accumulations of solid waste which can
be used for treatment as well as storage of dry materials. As they are
temporary in nature, design constraints on waste piles are generally less
rigorous than for liquid storage ponds or for long-term disposal facilities.
Even for hazardous waste handling purposes, waste piles may require only a
single liner under the facility; however, if a pile is closed as a permanent
disposal facility, it must be double-lined.
usually constructed in relatively flat areas,
short-term storage of high-volume dry wastes
This type of disposal unit is
Waste piles are used for the
such as coal ash, for stacking
of abatement gypsum, for stockpiles of bottom ash, and for surge storage of
any dry, high-volume waste. A schematic of a typical gypsum stack design is
presented in Figure 5-7. The most important environmental condition to which
a liner system is exposed to in a waste pile is the overburden pressure.
5.2.7 Heap Leach Pads and Ponds
Liner systems based on FMLs are being used as barriers in heap leaching
of low-grade ores to recover valuable metals, i.e. gold and silver. In this
relatively recently developed technology (Hoye et al, 1987), the liner system
acts as a barrier not only to prevent the loss of the dissolved metals but
also to prevent the release to the environment of the cyanide or sulfuric
acid solutions used to dissolve the metals. Pads from 0.25 to 50 acres in
size are constructed of native or modified clays, FMLs (e.g. HOPE, PVC, or
5-11
-------
TABLE 5-5. ENVIRONMENTAL CONDITIONS POTENTIALLY ENCOUNTERED
BY POLYMERIC FMLS AND OTHER MATERIALS OF CONSTRUCTION IN EXPOSURE
TO WASTE LIQUIDS AND LEACHATES IN SURFACE IMPOUNDMENTS
Condition
Potential effect on FMLs
Presence of water and organics
Presence of strong acids, bases
Presence of vast array of
different organic chemicals
Presence of liquid with
similar solubility parameter
Mechanical stress, both
uniaxial and multiaxial
Waste temperature
Presence of air (probable)
High overburden pressure
Hydraulic head on liner
system (up to 30 ft)
Swelling
Softening and loss in strength
Increase in permeability
Possible stress cracking
Reduction of seam strength
Extraction of compound ingredients
Stiffening
Extraction of compound ingredients
Stiffening
Swelling and potential dissolution
of FML
Creep of liner, cracking
Acceleration of other effects
Softening and loss in strength
Oxidative degradation
Biological growth in drainage
system, e.g. pipe
Settling of the native soil base
Shifting of the components in the
liner system, particularly the
components of the leachate drainage
and the leak-detection systems
Hydrostatic pressure on the liner
system potentially resulting in
distortion of liner and stress
due to uneven subgrade surfaces
High flow through any hole in the
liner that might develop
5-12
-------
CSPE), or asphalt. Both single- and double-lined pads and ponds with leak
detection and solution collection systems have been used.
Protective
Soil or Cover
(optional)
Top Liner
(FML)
,* . '. Drainage
'-.':•;•. :•':•-, Material
Secondary Leachate }'•'••'••'•'•'"rv.l'in '/^.^•r'^^-'-'''--'--'-1'•'••.••'••'•'•••.'.;•'-.•'••• '•':'•'.'•''-.'•/ ^
D« -icu^m \.::-: Drain 1<^Low Permeability Soil V/:V::.V:"V:-::A/ C*
Native Soil Foundation
NOTE:
Primary leachate collection system
not used in surface impoundment.
FML Component
Bottom
Composite Liner
Compacted Soil Component
of Bottom Composite Liner
NOT TO SCALE
Figure 5-4. Schematic of an FML/composite double-liner system for a surface
impoundment. (Based on EPA, 1985).
Protective
Soil or Cover
(optional)
Top Liner
(FML)
Filter Medium
Primary Leachate . vN
Collection and . •:.?
Removal System x- :... •
\ :'>
Secondary Leachate
Collection and
Removal System
FML Component
. of Composite Liner
.Pipes Low Permeability Soil . .• V.-X ^
' ' ,^v;^.: ' Compacted Soil Component
of Bottom Composite Liner
Native Soil Foundation
NOT TO SCALE
Figure 5-5. Schematic of an FML/composite double-liner system for a land-
fill. (Based on EPA, 1985).
5-13
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MATERIALS
RECOMMENDED
DIMENSIONS AND SPECIFICATIONS
NOMENCLATURE
01
Graded Granular Fitter Medium
Granular Drain Material
(bedding)
Flexible Membrane Liner (FML)
Granular Drain Material
(bedding)
Flexible Membrane Liner (FML)
Low Permeability Soil, Compacted in Lifts
(soil liner material)
NOTE:
Values lor FML thickness represent
actual values at all points across
roll width. FML thickness > 45 mils
recommended if liner is not covered
within 3 months.
Thickness > 6 in.
Maximum Head on Top of Liner = 12 in.
Thickness >12 in.
Hydraulic Conductivity >1 x1(T2 cm/sec
O-
• Drain Pipe -
o
Thickness of FML > 30 mils
(see note)
Thickness ^ 12 in.
Hydraulic Conductivity > 1 x I0-2cm/sec
Drain Pipe
Thickness of FML230 mils
(see note)
Thickness >36 in.
Hydraulic Conductivity <1 x 10"' cm/sec
-7
Prepared in 6 in. Lifts
Surface Scarified Between Lifts
Unsaturated Zone
Groundwaler Level
IP
///// Saturated Zone
W///////////M
Solid Waste
Fitter Medium
Primary Leachate Collection
and Removal System
Top Liner (FML)
Secondary Leachate Collection
and Removal System
Compression Connection (contact)
Between Soil and FML
Bottom Liner (composite FML and
compacted low permeability soil)
Nat.ve So,, Foundat.orv'Subbase
Figure 5-6. Schematic profile of FML/composite double-liner system for a hazardous waste
landfill presenting EPA draft guidance. Synthetic drainage media and synthetic
filter media can replace granular media if equivalency of performance is demon-
strated. (Based on EPA, 1985).
-------
CLAY STARTER
DIKE
CL&YEXTERCR
DIKE
GYPSUM STACK SITE PLAN
DIVIDER DIKE
ACTIVE PONO
DRAINED POND
CLAY EXTERCW
DIKE
HORIZONTAL
DSCMAftGEPIPE
CLAY STARTER
WKE
PER»BTER DtTOI
AW SUR6E POND
SECTION A-A GYPSUM STACK CROSS SECTION
Figure 5-7. Typical gypsum stack design. (Source: EPRI, 1980,
p 16-6).
The basic design and operational layout of heap leach projects are
similar at all facilities (Hoye et al, 1987). Low-grade ore is stacked
from 15 to over 50 ft high in engineered heaps on lined pads sloped 1 to
6% and a weak alkaline cyanide solution for gold and silver extraction and
sulfuric acid solution for copper extraction is sprayed over the ore. The
optimal pH of the solution for gold dissolution is 10.3, and the cyanide
content is maintained at approximately 250 mg L~l. This solution has a pH
of 10.3 and a cyanide content of 250 mg L'1. The solution percolates
through the heap and dissolves finely disseminated free metal particles. The
pregnant solution flows over the pad to a lined collection ditch, which
carries the pregnant solution to a lined pond. The product metal is then
recovered from solution by precipitation or carbon adsorption (gold). Heap
leach operations are typically zero discharge facilities. The leaching cycle
is relatively short (20 to 90 days). At the end of the cycle, the ore is
rinsed with fresh water to remove residual cyanide solution and dissolved
5-15
-------
metals. The leached ore is then usually left in place. A conceptual flow
diagram of the heap leach operation is presented in Figure 5-8.
Solution
Application
FML- Lined Leach Pad
Metal Recovery
Plant
\
Pregnant Pond
Barren Pond
Figure 5-8. Conceptual flow diagram of typical heap leach
operation. (Based on Leach et al, 1988).
The liner system in a heap leach system is usually exposed to a rel-
atively light load in comparison with other end uses, though some heap leach
projects are known to be 300 ft in depth which would yield a pressure of 350
psi on the liner system. However, an FML can be exposed to irregularities in
the surfaces containing it.
5.2.8 Secondary Containment Facilities
A relatively recent application of FMLs is in secondary containment of
substances that are potentially hazardous or could cause environmental
damage. This application is both for the secondary containment of hazardous
substances and liquids that may be stored in tanks above ground and of
liquids, such as petroleum and petroleum products, that are stored in under-
ground storage tanks. Waste liquids and in-process liquids may also be
stored in tanks that require secondary containment. In all cases, FMLs used
for secondary containment will contact the liquids being contained only in
case there is an emergency, i.e. in case there is leakage from the primary
storage tanks. When used for secondary containment of aboveground tanks,
such as for petroleum storage, the FMLs are usually covered with soil or
aggregate to protect them from weathering, wind lift, and mechanical damage.
Contact with the liquid being stored would be for relatively short time
periods until the liquid can be removed or evaporated. An FML used in
secondary containment of a liquid stored underground would not be exposed to
weather and to the liquid being stored except in the event of leakage from
5-16
-------
the tank. Figure 5-9 is a schematic of an underground storage tank with an
FML secondary containment.
Liner Turnback
Liner Sleeve
Monitoring Station
Typical Trench and Liner
Membrane Liner
Washed Gravel
Sand Leveling Bed
Dewatering Line
Figure 5-9. FML used for secondary containment. (Based on Haxo,
1984).
5.2.9 Uranium Tailings Ponds
Disposal of uranium tailings in surface impoundments has been the
conventional practice to date. Tailings are disposed of in any of several
types of surface impoundments near the mill, some of which are lined with
FMs. Such impoundments can be constructed as four-sided structures in
relatively flat areas; they can also be formed by constructing a dam or
embankment in an existing natural drainage area. In the latter case,
diversion ditches are constructed to divert runoff around the impoundment.
Embankments for impoundments have, in the past, been constructed of tailings,
but newer impoundments have been constructed from local earthern materials.
Heights of tailings embankments, which vary from 10 to 30 m (30 to 100 ft)
above surrounding terrain, can place a heavy overburden on a liner as well as
the drainage systems. The leachate generated in such facilities is essen-
tially inorganic, as is shown in Appendix A, and may be collected at the
bottom and recycled for use in the mill.
5.3 PRINCIPAL ENVIRONMENTAL STRESSES ENCOUNTERED BY FMLS AND
OTHER MATERIALS OF CONSTRUCTION IN SERVICE IN TSDFS
In the previous section the conditions that FMLs and other materials
of construction encounter in service in individual types of waste storage
and disposal facilities are described. As the principal function of a
lining system is to minimize or prevent the escape of toxic and hazardous
constituents of the wastes, it is necessary to prevent any breach in the
lining system. The original low permeability of a lining system must be
maintained throughout its service life.
5-17
-------
In reviewing the environmental stresses that construction materials
encounter in lining and drainage systems, it appears that these stresses
can be classified into two principal types: chemical and physical. These
stresses can affect the performance of an FML and other construction mate-
rials and reduce their service lives. Furthermore, these stresses may
act individually, but, in most cases, they will act together to determine
the service lives of these construction materials. Biological stresses,
which affect polymeric materials to a limited degree, have eliminated some
materials from subsurface applications. In particular, biological stresses
are a factor in the performance of some FMLs, such as those that contain low
molecular weight fractions. These stresses may become important factors in
very long exposures of materials that, at the present, appear to be resistant
to biodegradation.
In the following subsections these environmental stresses will be dis-
cussed in terms of the performance and permanance of FMLs.
5.3.1 Chemical Stresses
Due to the immense variety of wastes and combinations of dissolved
organic and inorganic chemicals in the wastes and waste liquids that are
contained in storage and disposal facilities, the effects of chemical stress
on the performance of liner systems is of primary concern, particularly for
long-term service. The effects of chemical stresses are manifested by:
- Degradation of the base polymer through oxidation, hydrolysis, photo-
oxidation, etc., which results in embrittlement and loss of physical
properties of the FML that may be important to its performance.
- Depolymerization, which results in softening and loss of physical
properties.
- Absorption of waste constituents, which can result in increased
permeability and loss in strength and other physical properties if
the amounts become sufficiently large.
- Extraction of components of the original FML compound.
The effects of chemical stress may take extended periods of time to become
apparent, particularly when the concentration of aggressive constituents in
a waste liquid is low.
Because of the known low permeability of polymeric FMLs to water,
gases, and other permeants, FMLs were considered as likely candidates for
lining waste storage and disposal facilities constructed on land. However,
at the time polymeric membranes were first being considered for such ap-
plications, there was great concern about the possible effects various
constituents in waste liquids would have on the serviceability of these
materials, even though considerable experience had already been accumulated
with using polymeric FMLs to contain specific liquids of known composition.
5-18
-------
A variety of FMLs had been successfully used in the impoundment and con-
veyance of water and in the impoundment of brines and some wastewaters. FMLs
had also been used to line facilities and equipment for handling very
specific chemicals and substances of known composition. Examples of such
facilities include lined chemical process equipment and storage tanks.
In this type of application, which was generally above ground, the required
service life was relatively short and, if a leak occurred in the lining, it
was accessible and could be repaired or replaced.
In all of these applications, there was no attempt to achieve a minimum
level of escape from the impoundment or conveyance system. In addition, the
materials being contained generally were not aggressive to the lining mate-
rials. However, as pointed out in Chapter 2, the waste liquids generated
by MSW or impounded in hazardous waste facilities contain a vast number of
different chemicals in complex mixtures, both organic and inorganic, some of
which in concentrated form can affect FMLs. It was not known how the various
FMLs would resist dilute aqueous solutions as well as uncontrolled concen-
trated solutions.
Exposure to some of the chemicals contained in waste liquids can
increase the permeability and result in changes in the stress-strain charac-
teristics of FMLs, and possibly even result in their disintegration with
time. These effects, which can be the result of absorption of constituents
from a waste liquid, are apparent on simple immersion in the liquid. Immer-
sion tests have been used by the polymer industry to determine the compati-
bility of polymeric compositions with various liquids in the selection and
design of compositions for service in contact with these liquids. In this
type of test, the weight changes and changes in physical properties are
measured to assess compatibility. Immersion-type simulations of field
service are performed as an initial assessment of the ability of the FML and
the other construction materials to perform in a liner system for a waste
storage and disposal facility.
This chapter, which presents data from simulated exposure tests, empha-
sizes the effect of the chemical environment on the tested FMLs. Data are
presented resulting from exposure of FMLs to actual waste streams to deter-
mine their chemical compatibility. Exposure conditions include both one-
sided exposure in test cells designed to simulate service environments and
two-sided in exposure in immersion-type tests. In addition, data are pre-
sented from immersion tests run either in neat solutions of various chemi-
cals that may be encountered in service or in dilute aqueous solutions.
Predominantly, the samples under exposure were not subject to concurrent
physical stressing.
Chemical stresses are also encountered in surface impoundments in
the area where the FML is exposed to the weather. The effects of the
chemical stresses are the result of:
- UV radiation.
- Infrared radiation.
5-19
-------
- Rain water.
- Oxygen.
- Ozone.
All these factors can contribute to the general aging of an FML exposed to
the weather. However, FMLs do not interact the same way with these factors;
for instance, unsaturated polymers will be not affected by the ozone which
can cause cracking in polymers such as neoprene and butyl rubber. Infrared
radiation interacts indirectly by raising the temperature of an FML and
thereby increasing the rate of oxidation and loss of volatile constituents
from the FML compound. The consequent effects on an FML can include harden-
ing, crazing or cracking of the FML surface, and reduction of physical
properties, such as tensile and tear resistance. Infrared radiation can thus
cause an FML to have less resistance to mechanical and abrasive damage.
Effects at the air-water interface can be more pronounced because of the
constant presence of chemicals in the water plus the oxygen and increased
temperature at the surface. Some of these stresses are simulated in tests
such as the tub test and in weathering tests.
5.3.2 Physical Stresses
A variety of physical stresses are encountered by FMLs and the other
construction materials used in liner and drainage systems. These stresses,
which can be independent of any chemical stresses, take place primarily
during construction and during the early service life of a waste facility
when the waste liquid is not in contact with the FML or the other construc-
tion materials. In the case of FMLs, some of the potential physical stresses
that can be encountered are:
- Stresses during installation due to the laying out of the FML on the
ground.
- Stresses during placement of a soil cover on an FML.
- Stresses due to dropped tools, etc., which could result in puncture.
- Stresses due to traffic.
- Shrinkage stresses at toes of slopes due to heating of the FML and
inadequate allowance for shrinkage.
- Low temperature stresses due to inadequate allowance for thermal
contraction.
- Stresses over irregularly shaped surfaces due to large aggregates
next to the surface of the FML (Figure 5-10).
- Distortion of an FML placed on a geonet due to inadequate thickness
or stiffness.
5-20
-------
Biaxial stresses which may cause rupture at low elongations, parti-
cularly of semicrystalline FMLs.
Figure 5-10. Schematic showing stresses in an FML that
would be caused by large aggregates in cover
and subgrade and compressive loading.
The effects of load can reduce the drainage capacity of both geotextiles
and geonets, since both of these materials will show significant reductions
in transmissivity with increasing overburden. Similar effects can be en-
countered in the improper sizing of drainage pipes.
Other physical stresses that are of importance are abrasion and fric-
tional effects. Abrasion of FMLs can take place during the installation of
a cover, and a lack of friction between the components in a layered system
can cause instability and slippage of the soil cover on an FML.
An important physical stress that affects all of the polymeric materials
that are used in the construction of waste storage and disposal facilities is
the effect of creep under constant or variable load. Creep is a time effect
which can cause puncture or rupture in an FML placed on an irregular surface
or cause compression or collapse of geotextiles or geonets after long-term
exposure effectively reducing their drainage capabilities. Polymeric mate-
rials under constant load are subject to fatigue failures such as have been
encountered in pipes (Lustiger, 1986).
Some of the physical stresses that have been simulated in performance-
type tests are described and discussed in this chapter.
5.3.3 Combination of Chemical and Physical Stresses
Once a waste storage and disposal facility is in service, FMLs and other
materials of construction in the facility are under both chemical and physi-
cal stresses. The effects under chemical and physical stresses can combine.
For example, the effects of creep under load can be highly aggravated by the
effects of softening due to absorption of components from the waste. This
would be particularly apparent with geonets and geotextiles that would be
used in the drainage systems. It also may affect the FML that is placed over
geonets. Simulation tests of this condition are presently being performed by
Southwest Research Institute. This kind of data is being requested by some
regional offices of the EPA as a part of the Part B applications.
5-21
-------
Other ways in which the combined chemical and physical stresses can
affect FMLs include the following:
- The absorption of organics and subsequent swelling of the FML can
cause it to increase in permeability.
- Unsaturated polymers such as butyl rubber and neoprene exposed
simultaneously to mechanical stresses and ozone can crack.
- Improperly formulated semicrystalline FMLs under mechanical stresses
when in contact with some chemicals can crack by environmental stress
cracking.
5.3.4 Biological Stresses
In general, the polymeric compositions that are being used in the
construction of waste storage and disposal facilities have shown a very high
resistance to biogradation, as is discussed in Chapter 4. Two types of
biological stresses have been observed:
- Biodegradation of monomeric plasticizers has occurred in compositions
compounded with these plasticizers, particularly in some PVCs.
- Fungal growth on the surface of FMLs in wastewater lagoons has occur-
red at the air-water interface. The fungal growth has dried on the
FML and caused the FML to shrink and crack starting at the surface.
The compounding of PVCs for FMLs can avoid for extended time the deteri-
oration by biodegradation of plasticizers through the use of biocides and the
proper selection of plasticizer. The potential fungal growth on the compo-
nents of a leak detection and/or drainage system is of concern because oxygen
is present in the system.
5.4 EFFECTS OF CHEMICAL STRESSES ON FMLS AND ANCILLARY
CONSTRUCTION MATERIALS
The chemical compatibility of the materials used in the construction of
waste storage and disposal facilities with the wastes to be contained was of
major concern when the concept of lining such facilities was first considered
in the late 1960s. Although there had been considerable use of liners in the
abeyance and storage of water, there was concern about the effect various
components of a waste liquid could have on an FML. Consequently, the EPA
undertook several research programs to develop information needed to estab-
lish the adequancy of various FMLs and other materials for use in the con-
struction of disposal facilities. In addition, other organizations also
initiated research programs to determine the adequacy of liner materials for
wastes generated by a specific industry.
5-22
-------
In this section, results of several of these programs involving MSW,
hazardous and toxic wastes, wastes from coal-fired power plants, and various
industrial liquids and wastes are reported. In these research programs
attempts were made to simulate conditions that would exist in the facilities
and to design tests that would predict the performance of the lining mate-
rials being tested. In particular, there was interest in the permeability of
FMLs to various organic chemicals, both in solutions and as neat chemicals.
Many of these FMLs were subjected to immersion-type tests with specific
chemicals and others to tests with simple aqueous solutions. An outcome of
the testing was the development of a liner-waste compatibility test by the
EPA, i.e. Method 9090 (EPA, 1986), which is described and discussed in this
section.
5.4.1 Simulation Tests of FMLs
5.4.1.1 Exposure to MSW Leachate in Landfill Simulators—
To simulate the conditions of one-sided exposure of FMLs to MSW landfill
leachate, Haxo et al (1982 and 1985a) placed 2-ft diameter liner specimens
under 8 ft of ground refuse in landfill simulators (Figure 5-11). An in-
dividual simulator consisted of a 2-ft diameter steel pipe, 10 ft in height,
placed on an epoxy-coated concrete base (Figure 5-12). The six polymeric
FMLs that were exposed as liners in the simulators were based on the follow-
ing polymers:
- Butyl rubber (IIR).
- Chlorinated polyethylene (CPE).
- Chlorosulfonated polyethylene (CSPE).
- Ethylene propylene rubber (EPDM).
- Low-density polyethylene (LDPE).
- Polyvinyl chloride (PVC).
Note: In this experiment, two sprayed-on FMLs and four admixed
liner materials were concurrently exposed and tested.
Results of these tests are reported in Sections 5.9 and
5.10, respectively.
The FML specimens were sealed in the simulator bases with epoxy resin so
that leachate could not bypass the liners. Each FML specimen had a seam
through the center which was made either by the manufacturer or in the
laboratory in accordance with the standard practice recommended by the
supplier. Approximately 1 yd3 of ground MSW was compacted above each liner
in approximately 4-in. lifts to yield a density of 1240 Ib yd~3 at a 30%
water content. The refuse was covered with 2 ft of soil and 4 in. of crushed
rock.
5-23
-------
- V DRAIN ROCK 3" THICK
GAUGE
SHREDDED REFUSE
MASTIC SEAL
CONCRETE BASE ^A
SAND -~Sj
*.
If
•
'
r
r
L/J
rnffett
''••-X
^
o
^^ x
/rf- * ^
* *v
^.^V
•«. '*
p
A-
. — SOIL COVER
1* FT. THICK
- — POLYETHYLENE
*— SPIRAL-WELD PIPE
2 FT. DIA. x 10 FT. HIGH
^— LINER SPECIMEN
"*\
H— DRAIN ABOVE LINER
GRAVEL
^- DRAIN BELOW LINER
Figure 5-11,
Landfill simulator used to evaluate FMLs specimen exposed to
MSW landfill leachate (Source: Haxo et al, 1982).
N s
)
THFT-^
1 FT
•t \ ^
.;. :.'v..V •'•'•SAND •;'.;•;
EPOXYSEAL
V-MEMBRANE LINER
Figure 5-12,
BAG
Base of the landfill simulator in which the FMLs were exposed.
The refuse at the bottom of the column was anaerobic. The
leachate was maintained at a 1-ft head by U-tubes. Plastic
bags were sealed at both outlets. Strip specimens of FMLs were
buried in the sand above the liner for exposure to leachate
(Source: Haxo et al, 1982).
5-24
-------
Tap water was introduced at the rate of 25 in. per year. Leachate
generated in each cell was ponded above the specimen at a 1-ft head by
continual draining into a collection bag. The simulators were designed to
collect any leachate that seeped through the liner specimens.
In addition to the FML specimens exposed as liners, 2.5 x 22-in. speci-
mens were buried in the sand above the liner specimens. Because leachate was
ponded to a depth of 1-ft above the liners, the buried specimens were totally
immersed throughout their exposure. These specimens were included in the
study to increase the number of FMLs being tested and to compare the effects
of two-sided exposure with the effects of one-sided exposure.
Two specimens of each of the FMLs tested were exposed in the simulators.
The simulators exposing the first set of specimens were dismantled at the end
of 12 months, and the simulators exposing the second set were dismantled at
the end of 56 months. The specimens removed from the simulators were tested
for physical and analytical properties. These tests are listed in Table 5-6.
The average composition of the leachate produced in the simulators
at the end of 12 months, when the first set of FML specimens was recovered
and tested, is shown in Table 5-7. The strength of the leachate, as measured
by total solids, nonvolatile solids, and total volatile acids in the simu-
lators decreased with time, as is shown in Figures 5-13 and 5-14. Initially,
the composition of the leachate generated by the simulators was fairly
uniform. However, as the concentrations of the dissolved salts and organic
and acids in the leachates decreased with time, variations developed in their
relative concentrations in the different simulators.
None of the FML specimens allowed any seepage. The epoxy seals in
three of the bases, however, failed during the last year of operation of
the simulators. The absence of seepage collected below the liners, except
in cases where the epoxy sealing ring disintegrated, confirms the very
low permeability of FMLs to MSW leachate. The results also show that the
seams in the FML specimens were adequate for these exposure conditions.
The exposed FML specimens were cut from the bases while they were
still wet and sealed in PE bags to keep them in a moist condition until they
were tested. All tests were made on samples as taken from the bases, i.e.
none of the samples was dried prior to testing. In all of the bases from
which the specimens were cut, the square-woven glass fabric and gravel below
the FML were in an "as new" condition, except in the base that contained
the CSPE FML, where a small area of the glass fabric was stained. Close
examination under magnification of the sheeting immediately above the stain
showed that a small piece of foreign material existed in the liner compound,
which resulted in a pinhole.
The results of the analytical and physical testing of the FMLs before
and after exposure are presented in Table 5-8. All tests on exposed samples
were made as soon as possible after removal from service. This procedure
determines the properties of the FMLs as they existed in the actual service
envi ronment.
5-25
-------
TABLE 5-6. TESTING OF POLYMERIC FMLS
Before and After Exposure to Leachate Produced
in the MSW Landfill Simulator
Thickness
Tensile properties, ASTM D412*
Hardness, ASTM D2240
Tear strength, ASTM D624, Die C
Water absorption at room temperature and 70°C,
ASTM D570 (unexposed only)
Seam strength, in peel and in shear
Puncture resistance, Federal Test Method Standard
No. 101C, Method 2065
Water vapor transmission, ASTM E96 (unexposed only)
Specific gravity and ash (unexposed only)
Volatiles, Matrecon Test Method 1 (Appendix G)
Extractables, Matrecon Test Method 2 (Appendix E)
*The references at the end of this chapter include the
ASTM standards used in this chapter, along with the
title of the standard.
TABLE 5-7. ANALYSIS OF LEACHATE
FROM MSW SIMULATOR*
Test Value
Total solids, % 3.31
Volatile solids, % 1.95
Nonvolatile solids, % 1.36
Chemical oxygen demand (COD), g L"1 45.9
pH 5.05
Total volatile acids (TVA), g L'1 24.33
Organic acids, g L~*:
Acetic 11.25
Propionic 2.87
Isobutyric 0.81
Butyric 6.93
aAt the end of the first year of operation
when the first set of FML specimens were
recovered.
Source: Haxo et al, 1982, p 49.
5-26
-------
2
UI
CO
Q
O
in
1977 I 1978
ELAPSED TIME
Figure 5-13.
Average solids content of the leachates produced In the MSW
simulators, November 1974 through July 1979. The data for
November 1974 through November 1975 are the averages for the
leachates from 24 simulators. Twelve simulators were disas-
sembled in November 1975 and, consequently, the data for
December 1975 through July 1979 are the averages for the
leachates from the 12 remaining simulators (Source: Haxo
et al, 1982, p 50).
Figure 5-14.
1976 ] 1977
ELAPSED TIME
Average TVA, as acetic acid, of the leachates produced in the
MSW simulators, November 1974 through July 1979. The data for
November 1974 through November 1975 are the averages for the
leachates from 24 simulators. The data for December 1975
through July 1979 are the averages for the leachates from 12
simulators (Source: Haxo et al, 1982, p 50).
5-27
-------
TABLE 5-8. EFFECT ON PROPERTIES OF POLYMERIC FMLS AFTER 12 AND 56 MONTHS OF EXPOSURE TO LEACHATE IN MSW LANDFILL SIMULATOR
cn
i
rv>
00
Item Test method*
Type of compound0
FKL number0
Analytical properties
Volatiles (2 h at 105°C), * MTM-1
...
...
Extractables after removal HTM-2
of volatlles, t
Solvent^
Physical properties
Thickness, mil
Tensile strength6, psi ASTM D412
Elongation at break6 ASTM D412
Set after break6, * ASTM 0412
Stress at 200%
elongation6, psi ASTM 0412
Tear strength (Die C)6, ppi ASTM D624
Hardness, Durometer points, ASTM 02240
10-second reading
Puncture resistances FTMS 101C,
Method 2065
Maximum force-average, Ib
Deformation at puncture, in.
Exposure
time, months
• * •
• * •
0
12
56
0
56
• • •
0
12
56
0
12
56
0
12
56
0
12
56
0
12
56
0
12
56
0
12
56
0
12
56
0
12
56
Butyl
rubber
XL
7
• • *
2.02
2.37
11.0
9.8
MEK
63
64
64
1435
1395
1465
400
410
405
17
14
12
695
685
750
175
200
185
51A
50. 5A
51A
44.8
49.5
50.0
1.22
1.20
1.25
CPE
TP
12
0.10
6.84
7.61
7.5
5.1
n-heptane
32
35
37
2275
1810
1960
410
400
385
430
210
160
1330
1090
1140
255
320
170
77A
65.5A
70A
47.0
49.8
51.8
1.04
0.98
0.98
CSPE
TP
6R
0.29
12.78
13.90
3.8
3.4
acetone
36
38
37
1765
1640
2110
250
300
235
115
105
60
1525
1245
1825
f
» • •
...
79A
64A
70A
32.9
57.0
58.2
0.60
0.88
0.86
EPDM
XL
16
0.50
5.54
5.74
31.8
28.3
MEK
51
51
49
1480
1455
1460
415
435
375
12
12
6
755
740
800
180
195
130
54A
51. 5A
51A
39.4
40.1
41.5
1.44
1.18
1.19
LOPE
CX
21
0.00
0.02
1.95
3'.37
MEK
12
11
10
2145
2465
2585
505
505
540
370
430
410
1260
1205
1325
390
495
405
• * •
...
13.9
14.8
17.1
0.76
0.80
1.24
PVC
TP
17
0.09
3.55
2.08
37.3
34.4
CC14+
CH3OH
21
21
22
2580
2350
2740
280
330
340
73
57
62
1965
1550
1810
335
450
285
76A
64A
70A
25.8
30.1
31.3
0.69
0.70
0.84
continued ...
-------
TABLE 5-8. CONTINUED
tn
t
ro
Item Test method
Seam strength
Location of seam prep-
aration
Bonding system ...
Peel strength, avgerage, ppi
Shear strength, ppi
Exposure
time, months
• • •
...
0
12
56
0
12
56
Butyl
rubber
Lab
Adhesive
(LVT)h
3.8
2.9
3.4
30.0
42.0
17.0
CPE
Lab
Sol vent
THF: Toluene
50:50
10.0
5.2
2.9
>57.0<
>35.0
17.0
CSPE
Lab
Cement
>30.01
3.4
1.8
>50.0'
40.2
10.0
EPDM
Factory
Adhesive
(LVT)h
5.4
2.0
7.1
44.5
24.3
18.0
LDPE
Lab
Heat
>15.61.J
• • *
>12.0
>20.2'
>11.4J.k
11
PVC
Factory
Cement
4.0
5.1
5.6
>2.72
>25.61
22i
aMTM = Matrecon Test Method.
bXL = Cross!inked; TP « thermoplastic; CX = semicrystalline thermoplastic.
Contractor's serial number. R indicates liner is fabric reinforced.
Solvents used in extraction: MEK * methyl ethyl ketone; CC^-tCI^OH • 2:1 blend of carbon tetrachloride and methyl alcohol.
eAverage of values in machine and transverse directions.
fTest method not applicable to fabric-reinforced materials.
9Rate of penetration of probe: 20 inches per minute.
nLow temperature curing cement.
^Break in specimen outside of seam.
JSeam failed at initial peak.
kSeam in the polyethylene liner used in the steel pipes; tabs in the liner specimens mounted in base were too short.
-------
To estimate the amount of MSW leachate absorbed by the FML specimens,
the v.olatiles contents of samples of the exposed materials were measured.
The results indicated that the CSPE, CPE, and EPDM FMLs, in this order, had
absorbed the greater amounts of leachate. The LDPE, PVC, and butyl liners
had the lower volatiles contents and absorbed lesser amounts of leachate.
The extractables contents of the exposed FML specimens were measured
to determine the nonvolatile organics in the FML compound and the effect of
exposure on the composition of the FMLs. By comparing the extractable con-
tents of an exposed specimen that has been dried with the extractable con-
tents of the unexposed FML, the amount of plasticizer or other ingredients
in the compound that has been extracted by the leachate can be calculated.
In all cases, the extractables after 56 months were about 10% lower than
the original extractables, indicating loss in the original plasticizer
contents.
The tensile properties of the FMLs varied; the tensile strength ranged
approximately from 1400 to 2500 psi. The changes with exposure time were
only modest and many may have been within experimental error, though several
showed trends toward increasing values probably a result of either loss of
plasticizer or, in the case of the CPE and CSPE FMLs, cross!inking. Tests
which reflect the stiffness of the materials, such as modulus (e.g. stress at
200% elongation) and hardness showed a minimum at 12 months. These minima
probably reflect the changes in the composition of the leachate with time; at
12 months the leachate concentration showed significantly higher organic
content than it did at 56 months. In all cases tear strength and puncture
resistance remained at satisfactory levels over the 56 months of exposure.
Though the FMLs showed good retention of properties during exposure,
there was a significant drop in several cases in the seam strength of the
materials, particularly in the CPE, CSPE, and EPDM specimens; however, this
loss of seam strength did not result in any seepage or leakage through the
specimens. The fact that no leakage occurred may have been due to the lack
of uniaxial or biaxial stress on the specimens. The simulators were designed
principally to assess compatibility. Stressing of the specimens was avoided
because of doubts that stress could be controlled.
Overall, the net changes in the physical properties of the FMLs result-
ing from 56 months of exposure were relatively minor. All of the FMLs
softened to varying degrees during the first 12 months, probably the result
of absorption of organic constituents of the leachate. In the interval of
time to 56 months, the PVC, CSPE, and CPE FMLs rehardened slightly, possibly
indicating, in the case of the PVC FML, loss of plasticizer and, in the case
of the CSPE and CPE FMLs, cross!inking of the polymers. They all recovered
most of their tensile properties that were lost due to the initial softening.
These three FMLs were all thermoplastic and uncrosslinked.
The results of this experiment are indicative of the concentration
effect and an equilibrium in the swelling with changing concentration of the
organics. Of the six polymeric FMLs, the LDPE best maintained original
properties during the exposure period, as is shown in Table 5-8; it also
absorbed the least amount of leachate. However, this FML, which was 10 mils
5-30
-------
in thickness, had too low a puncture resistance for use in lining a landfill.
This deficiency was confirmed by the difficulties encountered in its per-
formance as a lining of the steel pipes of the simulators, in the preparation
of the primary liner specimens, and in the fabrication and use of the LDPE
leachate collection bags. The butyl rubber and EPDM FMLs, which were cross-
linked changed slightly more in physical properties than did the LDPE FML
during the exposure period.
A comparison of the swelling of FMLs in water at room temperature and in
the leachate generated in the simulators is presented in Table 5-9. The data
for most of the FMLs showed that the swelling in leachate was significantly
higher than that in water in spite of the dissolved inorganic constituents in
the leachate. This greater swelling was probably due to the absorption of
organic constituents in the leachate. The neoprene and CPE FMLs, both of
which are chlorine-containing polymers, swelled less in leachate than in
water. As MSW leachate generally contains salt, this behavior reflects a
commonly observed effect of such polymers when they are immersed in aqueous
salt solutions as compared with immersion in water. The salt concentration
depresses the absorption of water by chlorinated elastomeric-type polymers.
5.4.1.2 Exposure to Hazardous Wastes in One-Sided Exposure Cells—
An exploratory experimental research project was conducted (1975 - 1983)
by Haxo et al (1985b and 1986) to assess the relative effectiveness and
durability of a wide variety of liner materials when exposed to nine differ-
ent wastes which were deemed to be hazardous by EPA in Cincinnati. The liner
materials were placed in a variety of exposures that simulated different
aspects of service in on-land waste storage and disposal facilities. These
exposures included immersion tests, pouch tests, and tub tests, the results
of which are described in separate sections in this chapter, and exposure in
one-sided exposure cells. The materials studied included compacted soil,
polymer-treated bentonite-sand mixtures, soil cement, hydraulic asphalt
concrete, sprayed-on asphalt, and 31 FMLs which were based on PVC, CPE, CSPE,
EPDM, neoprene, butyl rubber, ELPO, and PEL. Four semi crystal line polymeric
sheetings (PB, LLDPE, HOPE, and PP), though not compounded for use as liners,
were included in the study because of their known chemical resistance and use
in applications requiring good chemical and aging resistance. HOPE FMLs were
not commercially available in the United States at the time the project was
initiated. The results of exposing the admixed and sprayed-on liners are
discussed in Sections 5.9 and 5.10, respectively.
Eight polymeric FMLs were subjected to one-sided exposure in test cells
to nine actual waste liquids, including two acidic wastes, two alkaline
wastes, three oily wastes, a blend of lead wastes, and a pesticide waste.
Analyses of the various wastes are presented in Appendix J.
Each individual test cell functioned as a permeameter by allowing col-
lection of seepage that might occur below the liner specimen. Exposure in
the cell simulated the exposure of a liner at the bottom of a pond. Each
cell exposed a test specimen to approximately 1 cu ft of waste at a depth
of 1 foot. The cells designed to expose the FML samples are presented
schematically in Figure 5-15.
5-31
-------
Exposure specimens of each FML were fabricated in accordance with
the design shown in Figure 5-16. When pieces A and B were seamed together,
a 1.5-in. strip of polyethylene was placed along the edge of the seam on
the pull tab to prevent bonding of surfaces in this area so that the seam
could be tested in peel. Piece C was butted against the seam edge and tacked
in place as a spacer to produce a double thickness around the cell flange
area.
All of the specimens featured a seam that could be tested in both shear
and peel modes. Seams were made in accordance with the instructions of the
specific membrane supplier and, in some cases, with his materials. As most
seams in fabricated liners are parallel to the machine direction of the
sheeting, the seams fabricated in the test specimens were parallel to the
machine direction. All seams were 2-in. wide. For fabric-reinforced FMLs,
the seams were fabricated so that the edge of the top piece ("B") that faced
the waste was a selvage edge. This avoided exposing the cut ends of the
reinforcing fabric directly to the waste liquid. The underside of the FML
had a 1.5-in. tab left free for peel testing.
Before fabricating the liner specimens for mounting in the long-term
exposure cells, sample seams were made and tested. If the sample seams were
satisfactory, fabrication of the specimens began. Seams of most materials
were considered satisfactory if, when tested in shear, they did not fail in
the adhesive. For crosslinked liner materials, whose seams intrinsically
fail in the adhesive, the seams were considered satisfactory if they reached
strength levels previously determined to be acceptable. If seams were
unsatisfactory, a second set of sample seams was made and tested. In some
cases, cleaning the liner surface before seaming had been inadequate; in
others, insufficient adhesive had been applied. The EPDM and butyl rubber
FMLs came from the same supplier, and were seamed with the same adhesive
system, which was a low-temperature vulcanizing system and which included a
two-part adhesive, gum tape, and a caulking compound. Figure 5-17 presents
an unassembled exposure cell, with an FML specimen, before assembly. Table
5-10 shows the combinations of FMLs and wastes that were placed in exposure.
Testing of the FMLs before and after exposure to the hazardous wastes
was performed in accordance with the methods listed in Table 5-11. The
exposure times for each FML-waste combination are presented in Table 5-12.
The results of testing the exposed FMLs are summarized in Tables 5-13 through
5-16, which present the results of determining the percent volatiles, percent
extractables, percent retention of stress at 100% elongation, and percent
retention of elongation at break of the exposed samples. The data show the
effect of the waste at each exposure time on each of these properties.
They also show both the variation in magnitude of the effects on different
FMLs by a given waste and the different effects of the different wastes on a
given FML.
Information on the seams and on the retention of seam strength are
given in Tables 5-17 through 5-19. Table 5-17 presents information on the
type of seaming procedures along with information on the fabricator of the
seams. Table 5-18 presents the results of testing the seam strength of the
5-32
-------
TABLE 5-9. COMPARISON OF WATER AND MSW LEACHATE ABSORPTIONS
BY POLYMERIC FMLS IN ONE YEAR AT ROOM TEMPERATURE
Polymer
Butyl rubber
Chlorinated polyethylene
Chlorosulfonated polyethylene
Ethyl ene propylene rubber
Neoprene
Polybutylene
Polypropylene
Polyvinyl chloride
FML
number9
7C
22
24
12C
13R
23
3
4R
6R
14R
8
16C
25
26
9
20
27
10
11
15
l?c
19
Weight gain
immersion
In tap
water
1.60
1.70
1.10
13.1
19.6
15.5
17.4
18.0
9.20
11.2
1.40
4.80
1.50
1.60
22.7
0.25
0.28
1.85
1.85
2.10
1.85
0.60
after
, %
In MSW
leachateb
1.87
2.54
1.27
12.5
14.3
11.8
27.38
25.78
18.85
9.6
6.76
6.08
6.37
10.4
22.0
0.43
0.70
7.33
5.42
5.16
3.50
0.92
aMatrecon identification number; R = fabric-reinforced.
^Sample exposed in MSW simulators in sand above FMLs. All data
calculated from volatiles data. Volatiles of unexposed FML was
assumed to be zero.
cSample of FML also mounted in MSW landfill simulator bases.
Source: Haxo, 1977, p 156.
5-33
-------
Top Cover
Steel Tank
Epoxy Coating
Bolt
Caulking
Neoprene Sponge Gasket
Figure 5-15.
Design of cells for long-term exposure of FMLs to different
hazardous wastes. The area of the liner specimens in direct
contact with the wastes measured 10 x 15 inches. (Source:
Haxo et al, 1985b, p 76).
2.5"
O
0
0
O
r f
5.25" _.
Pull Tab
2" SEAM
O
10
CM
O
O
0
A
O 0 O
15"
BOTTOM PIECE
•FLANGE
SELVAGE
AREA
B
O
0
0
0
c
O
°
0 0
2" SEAM
^
O O
O
0
O
O
11"
UPPER PIECES FACING WASTE
ISOMETRIC DRAWING
(Sketch not to scale)
Upper
pieces
Bottom
piece
Figure 5-16. FML test specimens for long-term exposure in one-sided exposure
cells. (Source: Haxo et al, 1985b, p 71).
5-34
-------
TABLE 5-10. COMBINATIONS OF POLYMERIC FMLS AND HAZARDOUS HASTES TESTED IN ONE-SIDED EXPOSURE CELLS
en
i
oo
en
Wastes3
Acidic Alkaline
Polymer
Butyl rubber
Chlorinated polyethylene
Chlorosulfonated polyethylene
Elasticized polyolefin
Ethyl ene propylene rubber
Neoprene
Polyester elastomer
Poly vinyl chloride
FML
number"
57
77
6
36
26
43
75
59
Number
of
cells
8
10
10
15
8
8
12
15
"HN03-HF- "Slop
"HFL" HOAc" Water"
(W-10) (W-9) (W-4)
2
2
2
1 2 1
2
* * • ~ * * •
* * * £ * * •
1 2 1
"Spent
Caustic"
(W-2)
2
2
2
2
2
2
2
2
"Lead
Waste*
(W-14)
2
2
2
2
2
2
2
2
"Slurry
Oil"
(W-15)
...
...
...
2
• • *
• • *
2
2
Oily
"011 Pond
104"
(W-5)
• * •
2
2
2
...
2
2
2
Pest-
icide
"Weed "Weed
Oil" Killer"
(W-7) (W-ll)
2
2
2
1 2
2
2
2
1 2
aMatrecon waste serial number shown below identification. Analyses of wastes are summarized in Appendix J.
bMatrecon FML serial number.
Source: Haxo et al, 1985b, p 106.
-------
TABLE 5-11. TESTING OF POLYMERIC FMLS EXPOSED TO HAZARDOUS WASTES
Test
Analytical properties
Specific gravity, ASTM D297/D792
Volatiles, MTM-1 (Appendix G)
Ash, ASTM D297, Section 35
Extractables, MTM-2 (Appendix F)
Water absorption or extraction at room
temperature and 70°C, ASTM D570
Physical properties
Thickness
Tensile properties3, ASTM D412
Hardness, ASTM D2240, 5 second
(Duro A; Duro D also if Duro A >80)
Tear strengthb, ASTM D624, Die C
Unexposed
FML
Yes
Yes
Yes
Yes
3 at each
temperature
Yes
5 in each
direction
5
measurements
5 specimens
in each
direction
Exposed
FML
No
Yes
No
Yes
No
Yes
3 in each
direction
5
measurements
3 specimens
in each
direction,
Tear strengthb, ASTM D624, Die C
Puncture resistance, FTMS 101C,
Method 2065
Seam strength, in 90° peel,
ASTM D413C
Seam strength, in shear,
ASTM D882 (modified)c
Water vapor permeability, ASTM E96
5 specimens
in each
direction
5 specimens
3 specimens
3 specimens
3 specimens
3 specimens
in each
direction,
2 specimens
3 specimens
3 specimens
No
aMeasured with special dumbbell which featured smaller tabs, a shorter
overall length, and a shorter narrowed section in comparison with the
ASTM D412 Type IV dumbbell. At the time this project was initiated, it
was desired that all FMLs be tested in accordance with the same test
methods. Limited testing of the fabric-reinforced FMLs was performed
towards the end of the project in accordance with ASTM D751, Strip Method.
bUnreinforced sheeting, only.
cl-in. wide strips tested at a 2-ipm jaw separation rate.
Source: Haxo et al, 1985b, p 62.
5-36
-------
TABLE 5-12. EXPOSURE OF POLYMERIC FHLS TO HAZARDOUS WASTES IN ONE-SIDED EXPOSURE CELLS - DAYS OF EXPOSURE
Wastes3
Polymeric FML
Polymer
Butyl rubber
Chlorinated polyethylene
Chlorosulfonated polyethylene
Elasticized polyolefin
Ethyl ene propylene rubber
Neoprene
Polyester elastomer
Polyvinyl chloride
Number0
57R
77
6R
36
26
43
75
59
Acidic
"HN03-HF-
"HFL" HOAc"
(W-10) (W-9)
505
1218
459
1218
505
1218
2293 505
1217
497
1147
• • * • • •
323
509
1565 505
1352
Alkaline
"Slop "Spent
Water" Caustic"
(W-4) (W-2)
526
1249
526
1249
526
1249
2300 526
2677
526
124
526
1237
526
1237
1565 526
1249
"Lead
Waste*
(W-14)
499
1339
499
1334
499
1343
499
1343
499
1344
499
1342
499
1342
499
1345
"Slurry
Oil"
(W-15)
...
* • •
• • *
327
2355
• • •
• * •
328
327
Oily
"Oil Pond "Weed
104" Oil"
(W-5) (W-7)
• * • • • •
* • • . • •
521
1358
521
1357
521
1357
* • * • • •
521
1356
521
1357
521
1356
Pesticide
"Weed
Killer"
(W-U)
500
1258
500
1258
504
1258
494
2699
500
1258
494
1257
501
1258
500
1258
aMatrecon waste serial number shown below identification.
bMatrecon FML serial number; R = fabric-reinforced.
Source: Haxo et al, 1985b, p 111.
Analyses of wastes are summarized in Appendix J.
-------
TABLE 5-13. EXPOSURE OF POLYMERIC FMLS TO HAZARDOUS HASTES IN ONE-SIDED EXPOSURE CELLS - PERCENT VOLATILES9
en
i
CO
CO
Wastesb
Acidic Alkaline
Polymeric FMLC
Polymer
Butyl rubber
Chlorinated polyethylene
Chlorosulfonated polyethylene
Elasticized polyolefin
Ethyl ene propylene rubber
Neoprene
Polyester elastomer
Polyvinyl chloride
Number
57R
77
6R
36
26
43
75
59
Original
value,
%
0.29
0.14
0.51
0.15
0.50
0.45
0.26
0.31
Respective durations of exposure are presented in Table
bMatrecon waste serial number
cMatrecon FML serial number;
Source: Haxo et al , 1985b, p
shown below
identification.
R = fabric reinforced. Full
116.
"HN03-HF- "Slop "Spent
"HFL" HOAc" Water" Caustic"
(W-10) (W-9) (W-4)
5.92
11.46
* » • /•Oc • • *
13.18
4.69
* • • 1m 18 * • •
1.46 3.20 10.83
5.26
8.95
12.02
...
0.39
4.74
9.90 12.08 18.72
13.94
5-12.
Analyses of wastes are
unexposed property data
(W-2)
1.75
1.37
2.32
2.79
4.77
5.77
1.25
1.01
1.27
1.31
4.40
5.67
0.65
0.89
2.34
1.85
summarized in
are presented
"Lead "Slurry
Waste" Oil"
(U-14) (W-15)
2.79
3.53
11.58
19.20
1.08
11.44
1.03 0.38
1.53 4.02
2.83
5.25
18.01
17.50
2.63 0.40
1.72
3.34 0.29
4.43
Appendix J.
in Appendix F.
Oily
"Oil Pond
104"
(W-5)
...
...
3.69
10.11
7.51
10.25
2.15
5.12
• # •
* • •
12.99
21.31
1.27
2.59
1.70
4.19
Pesticide
"Weed "Weed
Oil" Killer"
(W-7) (W-ll)
4.10
4.79
4.99
7.91
8.00
9.73
0.13
0.58
3.34
6.29
11.29
13.63
0.60
2.92
2.30
3.61
-------
TABLE 5-14. EXPOSURE OF POLYMERIC FMLS TO HAZARDOUS WASTES IN ONE-SIDED EXPOSURE CELLS - PERCENT EXTRACTABLES*
Acidic
Polymeric FMLC
Polymer
Butyl rubber
Chlorinated polyethylene
Chlorosulfonated polyethylene
Elasticized polyolefin
Ethyl ene propylene rubber
Neoprene
Polyester elastomer
Polyvinyl chloride
Number
57R
77
6R
36
26
43
75
59
Original
value,
6.36
9.13
3.77
5.50
22.96
13.69
2.74
35.86
Respective durations of exposure are presented in Table
^Matrecon waste serial number shown below identification.
cMatrecon FML serial number; R =
Source: Haxo et al, 1985b, p 117.
fabric-reinforced. Full
"HFL"
(W-10)
* • •
• • *
• * •
* • •
5.40
• * •
• * •
* » »
• * •
34.42
"HN03-HF-
HOAc"
(W-9)
sies
10.09
9.41
4!62
5.40
7.09
21.36
• * •
10.77
13.36
Wastes1^
Alkaline
"Slop
Water
(W-4)
. ..
• • *
• * *
1.70
...
...
...
16.68 10.40
18.58
5-12.
Analyses of wastes are
unexposed property
data
"Spent
" Caustic"
(W-2)
7i86
g.'io
4.77
5.77
* • •
5.96
23.' 95
13.'69
3.85
3.31
34.62
35.61
summarized in
are presented
"Lead
Waste"
(W-14)
7.75
7.86
7.31
7.24
3.52
5.95
5.66
8.06
22.27
26.01
12.54
12.15
2.98
5.35
33.47
22.47
Appendix J.
in Appendix
Slurry
Oil"
(W-15)
* » •
• • •
• * •
* • •
13.94
23.88
• • •
* • *
9.91
39.63
F.
Oily
"Oil Pond "Weed
104" Oil"
(W-5) (W-7)
• » • • • *
• » * • * *
• • • * • •
17.00
• • * » • •
9.45
13.72
20.74
• • * • • •
• • • • • •
» • • • * »
15.86
5.68
7.28
32.62
29.99
Pesticide
"Weed
Killer"
(W-ll)
5.15
7.62
9.72
9.41
4.13
5.39
7.14
6.86
23.13
25.20
13.25
16.14
5.15
5.83
35.27
33.39
-------
TABLE 5-15. EXPOSURE OF POLYMERIC FMLS TO HAZARDOUS WASTES IN ONE-SIDED EXPOSURE CELLS - PERCENT RETENTION OF ELONGATION AT BREAK3
Wastes^
Acidic Alkaline
Polymeric FMLC
Polymer
Butyl rubber
Chlorinated polyethylene
Chlorosulfonated polyethylene
Elasticized polyolefin
Ethyl ene propylene rubber
Neoprene
Polyester elastomer
Polyvinyl chloride
Number
57R
77
6R
36
26
43
75
59
Original
value,
42d
402
242
665
450
320
575
995
"HN03-HF- "Slop
"HFL" HOAc" Water"
(W-10) (W-9) (W-4)
60
645
89
• * * 89 • • •
90
79
98 99 88
96
97
94
*•• •*• •*•
••• ^* •*•
4
153 200
249
"Spent
Caustic"
(W-2)
60
219
107
88
70
65
100
97
102
95
98
95
86
86
99
115
"Lead
Waste"
(W-14)
119
167
101
83
107
77
92
94
100
106
76
75
98
90
82
103
"Slurry
Oil"
(W-15)
• • •
• • *
• • •
96
97
• • •
...
77
113
Oily
"Oil Pond "Weed
104" Oil"
(W-5) (W-7)
• • • • • *
98
88
103
72
86
78
• • • * • •
86
92
95
92
152
174
Pesticide
"Weed
Killer"
(W-ll)
143
100
100
89
112
85
101
97
100
104
93
83
96
87
100
137
Respective durations of exposure are presented in Table 5-12.
^Matrecon waste serial number shown below identification. Analyses of wastes are summarized in Appendix J.
cMatrecon FML serial number; R = fabric-reinforced. Full unexposed property data are presented in Appendix
dUnexposed FML broke at less than 100% elongation.
Source: Haxo et al , 1985b, p 119.
F.
-------
TABLE 5-16. EXPOSURE OF POLYMERIC FMLS TO HAZARDOUS WASTES IN ONE-SIDED EXPOSURE CELLS - PERCENT RETENTION OF STRESS AT 100% ELONGATION*
-------
TABLE 5-17. SEAMS3 IN POLYMERIC FML SAMPLES EXPOSED TO HAZARDOUS WASTES IN ONE-SIDED EXPOSURE CELLS
Polymeric FML
Polymer
Butyl rubber
Chlorinated polyethylene
Chlorosulfonated poly-
ethylene
Y1 Elasticized polyolefin
no
Ethyl ene propylene rubber
Neoprene
Polyester elastomer
Polyvinyl chloride
number'3
57R
77
6R
36
26
43
75
59
Method of seaming
Vulcanizable adhesive furnished by supplier
of liner
Solvent weld with mixture of 1 part toluene
and 1 part tetrahydrofuran
Adhesive furnished by liner supplier
Heat sealed
Adhesive and gum tape furnished by supplier
Cement and lap sealant furnished by supplier
of liner
Heat sealed
Solvent weld using mixture of 2 parts tetra-
hydrofuran and 1 part cyclohexanone
Seam
width,
in.
2
2
2
0.5
2
2
0.5
2
Fabricator
Matrecon
Matrecon
Matrecon
Supplier
Matrecon
Matrecon
Supplier
Matrecon
3A11 seams were allowed to age at least a month before being tested or covered with wastes,
^Matrecon FML serial number; R = fabric-reinforced.
Source: Haxo et al, 1985b, p 120.
-------
TABLE 5-18. EXPOSURE OF POLYMERIC FMLS TO HAZARDOUS WASTES IN ONE-SIDED EXPOSURE CELLS - EFFECT ON SEAM STRENGTH MEASURED IN SHEAR MODE*
Seam strength in ppi
Polymeric FML
Polymer
Butyl rubber
Chlorinated polyethylene
Chlorosulfonated polyethylene
Elasticized polyolefln
Ethyl ene propylene rubber
Neoprene
Polyester elastomer
Polyvinyl chloride
Number*
57R
77
6R
36
26
43
75
59
Original
value,
PPl
>84.8d
48.39
62.19
28.89
39.0'
45.7"
21.29
>69.1d
Method
of
seaming
Cement*
Solvent
Cement
Heatk
Cement*
Cement6
Heat><
Solvent
Acidic
"HN03-HF-
"HFL" HOAc"
(W-10) (U-9)
... >67.8d
... >73.3d
... 27.1J
39.8"
52.79
57.49
32.49 29.29
32.09
47.9'
* • • • • •
69.29 74.79
79.0"
after exposure to different wastes'1
Alkaline
"Slop
Water"
(M-4)
• ••
• * *
• * •
31.3h
*• *
:::
* * *
* • •
71.6°.
"Spent
Caustic"
(H-2)
>78l6d
41.5"
46.0*1
64.0*
>76.3d
28.99
31.49
39.1'
45.9"
>5s!sd
...
50.49
63.69
"Lead
Waste"
(H-14)
64.69
>70.Td
26.3'
26.39
S8.2J
66.69
26.09
29.09
32.2'
13.9'
US
>ie!7d
53.19
45.09
"Slurry
Oil"
(IMS)
• • •
:::
:::
21.7d
24.49
...
* • •
>18.8d
59.39
Oily
"Oil Pond
104"
(H-5)
• • •
16.49
25.59
60.5"
60.3d
>19.39
18.39
** •
* • •
24.8P
14.69
28.29
>14.6d
60.99
77.19
"Weed
Oil"
(W-7)
:::
• • •
• • •
• * •
• • •
• • *
• • •
• • *
• • •
• • •
* • •
• • *
• • •
* • •
Pesticide
•Weed
Killer"
(W-ll)
69. lh
>68.8d
>38.8d
>44.5d
>61.3d
65.7*1
26.59
32.59
46.5]
44.41
>23.7d
34.9"
26.59
21.9"
46.0'
60.49
'Strip specimen 1-in. wide; Initial jaw separation, 4 in.; rate of Jaw separation, 2 ipm. All seams fabricated by Matrecon following manufacturers' recom-
mendations, except where otherwise noted. Value for seam strength is reported In pounds-per-inch-width (ppi). A "greater than" symbol is used to indicate
that the strength of the seam Itself Is greater than the value reported. See Table 5-12 for durations of exposure.
''Matrecon waste serial number shown below identification. Analyses of wastes are summarized in Appendix J.
°Matercon FHL serial number; R • fabric-reinforced.
dspecimens broke at clamp edge.
eLow-tenperature vulcanizing adhesive.
fSpecimens broke outside of seam area and not in the clamped area.
9Specimens broke at seam edge.
"One specimen broke at seaa edge; the other specimen broke in the clamped area.
'One specimen broke at seam edge; the other broke outside of seam area and not In the clamped area.
OOne specimen broke outside seam area; the other delamlnated in the seam area which had been separated.
kSean fabricated by supplier.
'Specimens delaminated in adhesive.
•"One specimen broke at seam edge; other delamlnated in adhesive.
"Specimens delamlnated In the plane of the bond between adhesive and liner surface.
°0ne specimen broke at clamp edge; other broke outside of seam area and not in clamped area.
POne specimen broke at clamp edge; other delamlnated In the plane of the bond between adhesive and liner surface.
ITwo specimens broke outside seam area; one specimen broke at clamp edge; two broke at seam edge.
Source: Haxo et al, 1985b, p 121.
-------
TABLE 5-19. EXPOSURE OF POLYMERIC FMLS TO HAZARDOUS HASTES IN ONE-SIDED EXPOSURE CELLS - EFFECT ON SEAM STRENGTH MEASURED IN PEEL MODE*
tn
Seam strength In ppl after exposure to different wastes'1
Acidic
Polymeric FML
Polymer
Butyl rubber
Chlorinated polyethylene
Chlorosulfonated polyethylene
Elasticized polyolefin
Ethyl ene propylene rubber
Neoprene
Polyester elastomer
Polyvinyl chloride
Numberc
57R
77
6R
36
26
43
75
59
Original
value,
PPl
8.0*
21.49
23.2J
21.01
4.9k
8.2"
20.89
15.29
Method
of
seaming
Cement6
Sol vent
Cement
Heat™
Cement6
Cement6
Heat™
Solvent
"HFL"
(W-10)
:::
• • •
• • •
...
22. 61
• • •
• • •
...
23.gr
"HN03-HF-
HOAc"
(W-9)
I'.lf
17.99
19.09
14.1*
12.5k
21.51
22.0'
5.9k
:::
...
28. 4S
34.09
Alkaline
"Slop
Water"
(W-4)
:::
• • •
• • •
• • *
22.01
• • *
...
:::
9.8r
"Spent
Caustic"
(W-2)
8.5'
21.99
21.0"
21.3f
28.4f
19.81
22.01
4.5k
5.4k
8.8"
10.8"
...
21.49
14.89
"Lead
Waste"
(W-14)
1$
17.39
13.79
26. 4 J
21.5k
19.81
22.21
3.5k
2.3k
3.3"
2.2"
17.4°
18. 3P
19.0s
16. 4r
"Slurry
Oil"
(W-15)
:::
• • *
• * •
isie'
...
:::
18.21
20.39
Oily
"Oil Pond
104"
(W-5)
:::
14.3*
11.49
16. 5f
uigi
:::
2.1"
3.6"
18.81
16. 2<*
23.1s
22. Of
"Weed
Oil"
(W-7)
• • •
• • •
• • •
• • •
...
...
...
• * •
...
Pesticide
"Weed
Killer"
(W-ll)
10. 9f
3.6f
20.09
16.29
21. 3f
15. If
20.91
23.21
5.0k
5.0k
7.6"
4.3"
20.31
19.51
18.19
23. or
aStrip specimen 1-in. wide; initial jaw separation, 2 in.; rate of jaw separation, 2 ipm. Value reported in pounds-per-inch-width (ppi) is average after
initial peak, except where otherwise noted. All seams fabricated by Matrecon following manufacturers' recommendations, except where otherwise noted. See
Table 5-12 for durations of exposure.
bMatrecon waste serial number shown below identification. Analyses of wastes are summarized in Appendix J.
cMatercon FML serial number; R » fabric-reinforced.
^Specimens delaminated in the adhesive.
6Low-temperature vulcanizing adhesive.
^Specimens broke by a combination of delamination of the adhesive and del ami nation of the lining material.
SSpecimens delaminated in the plane of the bond between the two finer surfaces.
^Specimens initially delaminated in the plane of the bond between the two liner surfaces, then broke at the line of peel in the course of the test.
'One specimen broke at the line of peel shortly after it began to peel; the other delaminated in the plane of the bond between the two liner surfaces.
JOne specimen delaminated in the lining material; the other delaminated in the adhesive.
^Specimens delaminated in the adhesive.
'Specimens broke at the line of peel after peeling approximately 0.1 in. Values reported are maximum stresses immediately before break.
""Seam fabricated by supplier.
"Specimens delaminated in the plane of the bond between adhesive and liner surface.
^Specimens ripped uncontrollably once peel was initiated"Value reported is maximum stress.
POne specimen broke at jaw bite; the other broke at the line of peel after peeling approximately 0.1 in.
^Specimens broke at jaw bite.
""Specimens initially delaminated in the plane of the bond between the two liner surfaces, then ripped uncontrollably.
S0ne specimen delaminated in the plane of the bond between the two liner surfaces; the other initially delaminated of the plane of the bond between the
two surfaces, then ripped uncontrollably.
Source: Haxo et al, 1985b, p 122.
-------
specimens measured in shear after exposure, together with data on the un-
exposed FMLs. Table 5-19 presents results of testing the strength of the
seams in the peel mode. All the data show the strength values in pounds-
per-inch width (ppi) and the locus of failure of the adhesion test specimen.
Figure 5-17. Unassembled exposure cell used for FML specimens. Shown are
the tank, the base filled with silica gravel, and an FML
specimen. (Source: Haxo et al, 19855, p 72).
The responses of the FMLs varied greatly to the individual wastes,
particularly to those waste liquids with oily constituents. The effects
varied from essentially no change during the exposures to complete failure.
The screening tests eliminated several of the polymeric FMLs from exposures
to oily wastes in the primary cells. The varied responses of the FMLs
occurred not only among the different polymer types but also within a single
type because of compound variations, e.g. plasticizer type and amount, cross-
linking, and fabric reinforcement. The results demonstrate the importance of
determining FML and waste compatibility during the selection and design
process.
The results of testing the exposed specimens are discussed in subsequent
subsections by individual FML.
5.4.1.2.1 Butyl rubber—The butyl rubber FML (No. 57R) was reinforced
with a nylon scrim which had a 22 x 11 epi thread count. It had a nominal
thickness of 31 mils and a vulcanized coating compound with a high ash
content which reflected the use of inorganic fillers in the compound.
Overall, except for peel adhesion, the butyl rubber specimens showed good
retention of their original properties on exposure to the four wastes it was
exposed to (Table 5-10). The effect of time was not large. The waste which
5-45
-------
caused the greatest change, perhaps, was the acidic waste "HNOs-HF-HOAc",
in which the butyl increased in volatiles content significantly and appeared
to soften. The butyl FML was not tested with the oily wastes because the
preliminary compatibility testing indicated that these wastes would have
caused significant softening and loss of tensile strength.
5.4.1.2.2 Chlorinated polyethylene (CPE)--The CPE FML (No.77) was an
unreinforced thermoplastic sheeting with a 30-mil nominal thickness. It had
an ash content of 12.56% and an extractables content of 9.13%. The CPE FML
appeared to perform satisfactorly with the inorganic aqueous solutions but
showed significant losses in properties after exposure to the oily wastes.
The CPE specimens showed significant increases in volatiles content in
the acidic, lead, and pesticide wastes, probably reflecting the absorption
of water (Table 5-13). The increase during exposure to "Oil Pond 104" waste
was probably due to absorption of oil as well as water. The smallest in-
crease in volatiles was in the specimen exposed to the "Spent Caustic"
waste. The modulus in all cases showed an initial drop and then an increase,
indicating initial swelling followed by crosslinking (Table 5-16). However,
there were losses in modulus in the lead waste and in the oily waste. The
only significant increase in the extractables during exposure was in the
sample exposed to the oily waste, "Oil Pond 104" (Table 5-14).
5.4.1.2.3 Chlorosulfonated polyethylene (CSPE)—The CSPE FML (No. 6R)
was reinforced with a nylon scrim that had a thread count of 8 x 8 epi. The
FML had a nominal thickness of 30 mils. The CSPE compound was a "potable"
grade compound which contained 3.28% ash and had an extractables content of
3.77%.
The results of exposing the CSPE FML to the five wastes that it was
exposed to indicated that this FML tended to absorb water and also some oil
when exposed to wastes containing oily constituents. The effect of aging
and exposure to wastes showed an increase in modulus and a decrease in
elongation at break, both of which are probably due to crosslinking of
the polymer (Tables 5-15 and 5-16). All of the CSPE specimens increased
significantly in volatile contents in all the wastes (Table 5-13). Though
volatiles of the CSPE liner increased in the spent caustic and pesticide
wastes, the magnitude appeared to be leveling off at the time the second
set was removed. The extractables changed only modestly during the exposure
(Table 5-14). The highest extractables content measured after exposure was
for the specimen that had been exposed to "Oil Pond 104" waste; in this case,
the extractables increased from 3.77 to 9.45%.
The greatest loss in seam strength was with the seams exposed to the
acidic waste; these losses probably reflect the loss in strength of the nylon
fabric. It should be noted that since work on this project was initiated,
there has been a shift from nylon to polyester as the reinforcing fabric that
is used in the manufacture of fabric-reinforced FMLs. It should also be
noted that "industrial-grade" CSPE is now used for service of this type and
it has a much lower water absorption than "potable-grade" CSPE.
5-46
-------
5.4.1.2.4 Elasticized polyolefin (ELPO)--The ELPO FML (No. 36) con-
tained a small amount of crystal!inity and had a nominal thickness of 20
mils, a specific gravity of 0.938, an ash content of 0.9%, and an extract-
ables content of 5.5%.
The ELPO specimens had only small increases in volatiles content and
showed good retention of properties in those wastes that were predominantly
water; for example, the pesticide, the lead, and the "Spent Caustic" wastes.
The specimens exposed to those wastes that contained oily constituents,
particularly the "Oil Pond 104" waste and the "Slurry Oil" waste, increased
in volatiles and extractables contents, which resulted in major drops in
tensile strength and modulus and softening of the sheeting. There were also
a significant increases in volatiles content by the specimens exposed to the
acidic waste, "HN03-HF-HOAc", and the alkaline waste, "Slop Water".
5.4.1.2.5 Ethylene propylene (EPDM)--The EPDM rubber FML (No. 26)
was cross!inked and had a nominal thickness of 30 mils. It had a specific
gravity of 1.169, an ash content of 7.67%, and an extractables content of
22.96%. The high extractables content shows the high oil content that is
common to many EPDM compounds. This FML was not tested with the oily wastes
based on results of the preliminary compatibility tests and the oil sensi-
tivity of this type of rubber. The EPDM FML was affected only moderately by
the four wastes to which it was exposed. Of the four wastes, the acidic
waste appears to have been the most aggressive toward the EPDM compound; the
effects, however, were not large. The seam strength was low before exposure
and decreased with exposure, indicating inadequacy of the seaming method.
5.4.1.2.6 Neoprene—The neoprene FML (No. 43) that was tested was
crossl inked and not fabric-reinforced. It had a nominal thickness of 31.3
mils, a specific gravity of 1.477, an ash content of 12.3%, and an ex-
tractables content of 13.69%.
Because neoprene is generally considered to be an oil-resistant rubber,
it was exposed to the oily wastes, as wastes of this type are aggressive to
many of the lining materials. All the neoprene specimens increased sub-
stantially in volatiles content in all of the wastes, increasing from 0.45%
to 11.29 - 21.31%, except in the "Spent Caustic," in which the values in-
creased to 5.67%. On the other hand, the extractables content changed little
even for the specimens exposed to the oily wastes. Consequently, it appears
that most of the liquid absorbed by the neoprene specimens was water. The
neoprene specimens exposed to the lead waste, the "Oil Pond 104" waste, and
the pesticide waste softened considerably and had a low retention of stress
at 100% elongation (Table 5-16). This is probably the result of absorbing
water. The specimens exposed to the "Spent Caustic" waste softened little
and retained their elongation best, probably the result of the high dissolved
solids content of the wastes. Low absorption of highly concentrated brines
is characteristic of neoprene compounds.
The oil resistance normally associated with neoprene was not apparent
in these tests. Figure 5-18 shows the swelling that occurred in a neoprene
sample that had been exposed to the "Lead Waste."
5-47
-------
Figure 5-18.
Two photographs of the recovered neoprene FML (No. 43) that had
been exposed to the lead waste for 499 days. Fig. 5-16a shows
the exposed FML in the test cell after it had been cleaned.
Fig. 5-16b shows the exposed FML specimen after removal from
the eel 1.
5-48
-------
5.4.1.2.7 Polyester elastomer (PEL)--The polyester elastomer FML (No.
75), "a developmental product with a thickness of 7 mils, was based on a
semi crystal line polymer that melts in the 188° to 207°C range. It had a
specific gravity of 1.236, an extractables content of 2.74%, and an ash
content of 0.38%. A thermogravimetric analysis of this FML indicated that it
contained 91% polymer, 3% plasticizer, and 6% carbon black. The PEL sheeting
was included in this project because of its reported resistance to hydro-
carbons and other oily materials. This was the only FML in the program that
failed by cracking and leaking on exposure to a waste, in this case, the
acidic waste "HN03-HF-HOAc". This shows the sensitivity of this polymer to
acidic materials which caused it to degrade by hydrolysis. Exposure in the
oily wastes caused the PEL to decrease significantly in its physical prop-
erties particularly after exposure to the "Slurry Oil" waste. This FML had
its best retentions in the pesticide and the "Spent Caustic" wastes. New
versions of this type of FML are now available with improved properties for
liner applications.
5.4.1.2.£i Polyvinyl chloride (PVC)—The PVC FML (No. 59) had a nominal
thickness of 30 mils, a specific gravity of 1.280, an ash content of 6.97%,
and an extractables content of 35.86%. The high extractables, largely
plasticizer, is equivalent to about 60 parts per 100 g of PVC resin.
The PVC FML showed considerable variation in its response to the dif-
ferent wastes to which it was exposed. The variation was largely related to
the amount of swell and the loss of plasticizer that took place during the
exposure. The volatiles increased for all of the exposed specimens except
for the specimen that was in contact with the "Slurry Oil" waste (Table
5-13). In most cases, the amount did not increase greatly after the initial
exposure time. However, the increase was substantially greater for the
second specimens of this FML tested after exposure to "Slop Water" and the
strong acid, "HN03-HF-HOAc." The extractables of the exposed specimens
varied considerably (Table 5-14); all, however, tended to be lower than the
original value, indicating loss of plasticizer. The specimen exposed to the
"Slop Water" had the lowest extractables content, indicating a major loss of
plasticizer. The specimens in the acidic waste also had a significant loss.
The extractables content of the specimens exposed to the lead waste and to
"Oil Pond 104" waste also dropped during exposure, indicating some loss of
the plasticizer to the oily wastes. The effects of the exposure on physical
properties was also severe in some cases. The specimens that had been
exposed to the "Slop Water" lost almost all of their elongation and became
very hard (Table 5-15). The specimen that had been in contact with the
acidic waste, "HN03-HF-HOAc," lost in elongation and more than doubled
in stress at 100% elongation (Table 5-16). The specimens exposed to "Oil
Pond 104" waste and the weaker acidic waste, "HFL," also increased signi-
ficantly in modulus.
5.4.1.3 Exposure to Wastes from Coal-Fired Electric Power Plants—
A similar study to that described in the previous section is being
carried out for the Electric Power Research Institute by Haxo et al (1987),
using the same type of exposure cell to simulate conditions in impoundment
facilities.
5-49
-------
Eight polymeric FMLs are being exposed to eight different wastes or test
fluids. The eight FMLs are:
- Butyl rubber.
- Chlorinated polyethylene.
- Chlorosulfonated polyethylene (two compositions: a potable and an
industrial grade).
- Ethylene propylene rubber.
- High-density polyethylene.
- Polyvinyl chloride (two compositions).
Eight types of wastes were selected for the long-term primary exposure
program: three fly ashes of different pHs, a flue-gas desulfurization sludge,
a flue gas desulfurization sludge/fly ash/lime mixture, an acidic boiler-
cleaning waste, an acidic air-preheater cleaning waste, and an alkaline waste
brine from water treatment. These eight wastes, which are typical of waste
streams found in coal-fired power plants, may contaminate the groundwater
or are potentially aggressive to FMLs. Each waste was analyzed for chemical
constituents. On the basis of these analyses, the boiler-cleaning and
air-preheater wastes appeared to be the most aggressive to liners. They
were, therefore, used in the liner-waste compatibility immersion tests.
Several polymeric FMLs have been immersed in a flue-gas desulfurization
sludge not used in the primary exposure program and in leachate from the
alkaline fly ash. Two other test liquids, 5% brine and deionized water,
were also used in exposure tests with polymeric FMLs.
Because some organic compounds can potentially have adverse effects
FML liner systems, the presence of dissolved organics in the waste stre
was of special concern. However, none of the eight wastes ||<:pH ">" 1
project contain significant amounts of organics.
in
streams
used in this
5.4.1.4 Exposure in Tub Tests—
As part of the research program described in Section 5.4.1.2, Haxo
et al (1985b and 1986) exposed samples of polymeric FMLs in tub tests under
conditions that simulated some that exist in a lined surface impoundment in
which the liner is in contact with the waste liquid and is not covered with
soil. The effects of exposure to sun, temperature changes, ozone, and other
weather factors could be assessed together with the effect of a given waste
on a specific FML. The level of the waste was allowed to fluctuate so that
an area of FML was subjected intermittently to the both the waste and the
weather. This alternating of conditions, which is encountered in surface
impoundments, is especially harsh on lining materials. A detailed descrip-
tion of the tub test procedure is presented in Appendix H.
The tubs used in this study were constructed of 0.75-in. exterior
grade plywood with sides sloping outward at a 1 horizontal^ vertical slope
5-50
-------
(Appendix H, Figure H-l). The inside base measured 7 x 12 in., and the
opening at the top measured 19.75 x 24.5 inches. The tub depth was 10
inches.
An exposure test specimen consisted of a 40 x 48-in. sheet which, in
most cases, incorporated a seam through the center. In this way the seam
durability as well as that of the FML was assessed. The test specimens were
draped over the tubs and folded to fit the inside corners and edges of the
tubs; the excess material was allowed to hang freely over the edges. In this
manner, there was a considerable number of folds and sharp angles in the
liner while it was exposed, particularly over the corners of the tubs (Ap-
pendix H, Figure H-2). If the FML was sensitive to the waste or to ozone,
cracking or crazing would develop.
The tubs were filled from 3/4 to 7/8 with the wastes. Approximately
4.5 gal of waste was required to fill each tub. The tubs were placed in a
lined shallow basin to prevent waste overflow or leaks from contacting the
roof top.
During the exposure, the liners were inspected visually on a regular
basis for cracking, opening of seams, and other forms of deterioration.
The tubs were covered during rainy periods. The liquid levels and temper-
atures were measured and recorded at regular intervals. The levels were
allowed to fluctuate about 4 inches. Water was added when levels became too
low due to evaporation. The shallowness of the tubs and the dark color of
the FMLs resulted in high heat absorption when the tubs were exposed to
sunlight; the liners and the wastes were quite warm on sunny days. The air
and waste temperatures were monitored regularly; waste temperatures ranged
from 10° to 66°C (Haxo et al, 1985b, p 160).
During much of the year, the oily wastes accumulated water (from dew)
at the bottom of the tubs which did not evaporate significantly. An oil-
water mixture had to be pumped from the bottom of the tubs to maintain liquid
levels and prevent the oily wastes from overflowing. The oil-water mixture
was removed and analyzed for pH, electrical conductivity, percent solids, and
other parameters as appropriate. During rainy periods, water in the catch
basin was also monitored for pH and conductivity to determine whether there
was any leakage from the tubs containing highly acidic or highly alkaline
wastes.
The seven FML-waste combinations that have been removed from exposure
are shown in Table 5-20. These seven combinations include a range of six
different FMLs and three different wastes. Three tub liners, including two
liners of the same FML (ELPO) exposed to the same waste ("Oil Pond 104"),
were removed from service because the liners had failed in the waste-air
interface area due to cracking at a fold. The tub lined with a neoprene FML
containing the waste liquid "Oil Pond 104" also failed and was subsequently
removed from service. The results of testing these three liners were re-
ported in Haxo et al (1985b). The procedures used in testing the liners
removed from service are presented in Appendix H. An analysis of the wastes
used in these tests is presented in Appendix J.
5-51
-------
TABLE 5-20. COMBINATIONS OF POLYMERIC FMLS AND WASTES
REMOVED FROM EXPOSURE TUB TEST AND EXPOSURE TIMES IN DAYS
Polymeric FML
Polymer Number3
CPE 77
Waste
Acidic
"HN03-HF-HOAc"
(W-9)b
• • •
identification
Alkaline
"Spent
Caustic"
(W-2)b
Tub 9
(2774 days)
Oily
"Oil Pond
104"
(W-5)b
• • •
CSPE 6R Tub 10
(2697 days)
ELPO
EPDM
Neoprene
PVC
36
8
82
11
• • •
Tub 11
(2046 days)
• • •
Tub 12
(2629 days)
• • •
Tub 7
(2479 days)
» » »
• • •
Tub IC.IAC
(506 days)
(1308 days)
• • *
Tub 6C
(2008 days)
• • •
aMatrecon FML serial number; R = fabric-reinforced.
^Matrecon waste serial number. See Appendix J for analyses
of the wastes.
cResults of testing these tubs were presented in Haxo et al
(1985b).
5. 4. 1.4. I—Testing of first failed ELPO liner exposed to "Oil Pond
104" waste — ELPO had not been recommended for oily applications; however, it
had functioned satisfactorily in preliminary compatibility tests. The first
ELPO liner exposed to "Oil Pond 104" waste failed after 506 days of exposure
at a crack in a fold at the air-waste interface at the waste surface on the
north sloping side of the tub. The liner appeared to have swelled consider-
ably in this area. On removal from the tub, physical tests were performed at
four exposure locations:
- Under the waste at the bottom of the tub.
- In the waste-shade zone on the south side.
- In a shade zone only where the sheeting was draped over the north
edge.
- In a waste-sunlight zone on the north slope.
5-52
-------
The waste-sunlight zone encountered the most severe exposure environment
the 1iner material.
for
5.4.1.4.2 Recovery and testing of the second failed ELPO liner exposed
to "Oil Pond 104" waste—The second ELPO liner, which did not have a seam,
replaced the first liner that had failed. This liner failed after 1308 days
of exposure in much the same fashion as the first. It cracked at a fold at
the air-waste interface.
On removal from the tub, this
swelling at the air-waste interface
liner in accordance with the pattern
removed from across the north-south
FML showed considerable distortion and
area. Test specimens were cut from the
shown in Figure 5-19. A 1-in. strip was
axis of the tub liner. The thickness of
the strip was measured along its length
results are presented in Figure 5-20.
with a roller type gauge, and the
NORTH
WEST
41 in.
io a
I Bottom
I area of
|O D Tub
1 • in. strip used
with roller gage
]DO
North
Top
North
Sloping
Side
Bottom
South
Sloping
Side
South
Top
EAST
EXPLANATION
X Visible cracks
Area swollen
and wrinkled
—47 in.—
SOUTH
Figure 5-19. Drawing of exposed ELPO liner showing locations where the test
specimens were cut and the orientation with respect to the tub
and to the north. Location of strip for measuring thickness
across specimens is also shown. (Source: Haxo et al, 1985b,
p 163).
5-53
-------
237
23.1
(0
i
z
UJ
o
(3 225
213
NORTH NORTH
Weather SIDE
exposed
BOTTOM
(Under waste which
may contain water)
SOUTH SOUTH
SIDE Weather
exposed
i
i
i
i
12 16 20 24 28 32
NORTH -*~ SOUTH, INCHES
36
40
Figure 5-20.
Thickness of strip of exposed ELPO liner cut across the width
of the liner in north-south direction. (Source: Haxo et al,
1985b, p 163).
The test results for the liner samples taken from the different lo-
cations are presented in Table 5-21 together with the results of testing
the unexposed FML. As in the case of the first failed ELPO liner, the
effects of the absorption of the oil are large. The specimens taken from the
north interface had an extractables content of almost 33% in comparison with
the 5.5% extractables content of the unexposed FML. Retention of the tensile
strength of the FML at the interface area on both the north and south sides
was low. The tensile strength as a function of the thickness of the exposed
FML is shown in Figure 5-21. The data on all of the individual tensile
determinations have been included in the plot.
5.4.1.4.3 Testing of the neoprene liner exposed to "Oil Pond 104"
waste—The neoprene liner, which faiTed in the seam, was the third to fail
in the oily waste, "Oil Pond 104." The results of testing the liner are
presented in Table 5-22. The FML absorbed a significant amount of oily waste
as is shown by the increase in extractables in the areas where the liner was
in contact with the waste.
As in the case of the two ELPO liners, the extractables of the sheeting
exposed at the bottom of the tub was lower than that of the sheeting exposed
on the sides at the air-waste interface area. This may be an indication
either that exposure was more severe at the interface or that enough water
was in the waste at the bottom of the tub to reduce swelling. The retention
of physical properties is inversely related to the degree of swelling by the
oily waste.
5-54
-------
TABLE 5-21. PROPERTIES OF SECOND ELPO LINER EXPOSED TO AN OILY WASTE
("OIL POND 104") FOR 1308 DAYS IN TUB ON LABORATORY ROOF IN OAKLAND, CA
Variation in Location in Tub
Property
Anal yjtlca 1 p r ope rt i e s
Volatiles, %
Extractables, %
Physical properties3
Thickness, mil
Tensile at break
Elongation at break
Stress at 100%
elongation
Stress at 200%
elongation
Tear strength
Puncture resistance:
Stress
Elongation
aTensile and tear values
Properties
of unex-
posed FML
0.15
5.50
23
2620 psi
665%
925 psi
1020 psi
380 ppi
26.3 Ib
0.97 in.
are average
North
at top
1.65
7.54
22.5
84
80
97
95
94
119
144
d for both
Location
North
at
inter-
face
6.2
32.7
25.8
Retenti
29
63
49
47
41
71
132
directions
in tub
Waste
only
8.6
20.7
24.6
on, %
48
89
63
61
56
68
118
•
South
at
inter-
face
8.4
23.0
125.8
37
83
59
56
48
69
116
Source: Haxo et al, 1985b, p 164.
The results of testing the seam in the tub liner are presented in
Table 5-23. The seam was made with a low-temperature vulcanizing cement.
The top edge of the seam was caulked over with a lap sealent. The seam under
the waste had a much lower seam strength than the seam that had not been in
contact with the waste.
5.4.1.4.4 Summary of results of testing other FMLs exposed in roof
tubs—The results of testing the other FMLs exposed in the roof tubs are
summarized in Table 5-24.
5-55
-------
80
<
UJ
oc
60
t- 60
u,
O
1 „„
20
EXPLANATION:
O MACHINE DIRECTION
A TRANSVERSE DIRECTION
2 4 6 B 10
PERCENT CHANGE IN THICKNESS
Figure 5-21.
Retention of tensile strength of ELPO exposed in the oily
waste, "Oil Pond 104," for 1308 days, as a function of change
in thickness due to swelling. (Source: Haxo et al, 1985b,
p 164).
5.4.1.4.5 Discussion of results—The results of the roof tub tests show
the importance of location within a facility on the effects of exposure on an
FML. The aging that occurs at the different locations can vary considerably,
particularly if there is stratification of the wastes. The cracking in the
PVC 11 FML exposed to the acidic waste and the EPDM 8 FML exposed to the
alkaline waste was due to exposure to the weather. It should also be
noted that these were areas where the liners were folded, that is, in place
where the FML samples were under constant stress. The cracking of the EPDM
8 FML was probably ozone cracking, an unusual effect in EPDM sheeting. The
cracks that developed in the ELPO 36 liners at the air-waste interface were
also at folds. The neoprene 82 and ELPO 36 FMLs had their most significant
losses in properties at the air-waste interface on the south-facing slope.
The CSPE 6R liner also developed a leak and two blisters at the air-waste
interface. The neoprene 82 FML failed in the seam area exposed to oily
waste, and the seam in the EPDM 8 FML had begun to delaminate in the area
exposed to the acidic waste. Adhesives were used in making both seams.
These results indicate the difficulties involved in seaming crosslinked FMLs
and the necessity of compatibility testing of seams.
5.4.1.5 Simultaneous Exposure to Simulated Tailings and Stress--
Mitchell and
different FMLs at
Cuello (1986) performed simulation exposure tests on three
three different temperatures in specially designed exposure
5-56
-------
TABLE 5-22. PROPERTIES OF A NEOPRENE FMLa EXPOSED TO AN OILY WASTE ("OIL POND 104")
FOR 2008 DAYS IN TUB ON LABORATORY ROOF IN OAKLAND, CA
Samples Taken From Different Locations in Tub
Property
Analytical properties
Properties
of unex- South
posed FML top
Direction
of test
Position in tub
South
slope Bottom
North
slope
North
top
Extractables, %
Volatiles
Loss over desiccant
at 50°C, %
Physical properties
13.43
12.28
0.6
30.09
5.1
25.33
6.5
28.94
2.1
aCrosslinked 60-mil neoprene
Source: Haxo et al, 1985b, p
FML without fabric reinforcement (Matrecon No. 82).
165.
12.71
0.5
Thickness (average), mil
Tensile at break
Elongation at break
Stress at 100% elongation
Stress at 200% elongation
Tear resistance
Puncture resistance
Thickness
Maximum force-average
Deformation at puncture
Hardness, durometer points
5-second reading
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
61
1835 psi
1675 psi
390%
410%
405 psi
360 psi
875 psi
705 psi
185 ppi
180 ppi
60.5 mil
53.9 Ib
1.2 in.
57A
63
89
89
71
70
152
146
135
144
88
89
105
97
51
+ 7A
75
51
39
84
79
40
28
52
42
36
35
126
54
84
-31A
77
Retention, %
41
45
79
75
29
34
44
54
31
29
129
64
81
Change in points
-29A
75
31
43
96
89
16
29
24
41
36
30
131
32
73
-33A
65
85
92
74
70
154
161
132
155
84
81
107
102
68
+8A
-------
columns, which attempted to simulate conditions at the bottom of a tailings
pond. A schematic of the exposure column is presented in Figure 5-22. The
columns were made of 0.61-m (24-in.) stainless steel pipe. FML samples in
which seams were incorporated were placed over a sand subgrade and sealed
between the flanges of the column. The FMLs were covered with a 25-cm layer
of fine silica sand to simulate tailings. Seventy liters of simulated
leachate were added to each column. The load created by tailings was simu-
lated by a press. Air pressurization of the test column was used to maintain
a load equivalent to approximately a 5 to 6-m head of water on the sand above
the FML. The temperature of the columns was maintained by fluid circulating
in copper coils around the column exteriors. Operation of the columns
included continuous temperature recording and daily monitoring of pH, liquid
level, and air pressure. If the pH rose above 2.5,
to keep the pH between 2.0 and 2.5 The leachate was
a day on weekdays. The column presses were loaded
position.
sulphuric acid was added
circulated several hours
biweekly and locked into
TABLE 5-23. SEAM STRENGTH OF NEOPRENE 82 FML SAMPLE
AFTER 2008 DAYS OF EXPOSURE IN TUB CONTAINING
OILY WASTE, "OIL POND 104"
Location in tub of sample tested
East West
Mode of test top Bottom top
Shear
Maximum, ppi
Locus of break
58.8
AD-LSa
8.1
AD-LSa
55.1
AD-LSa
Peel , ppi
Maximum^3, ppi
Average, ppi
Locus of break
9.2
6.5
AD-LSa
1.6
0.8
AD-LSa
8.2
5.5
AD-LSa
aAD-LS = Del ami nation between adhesive and liner
surface.
^Maximum peel strength occurred at caulked edge.
Source: Haxo et al, 1985b, p 166.
Samples of HOPE, PVC, and CSPE FMLs were exposed in the columns at
three different temperatures for 18 weeks. In the original experimental
design, all FMLs were to be exposed at 18°, 48°, and 78°C. However, the
combination of stress and elevated temperature apparently caused the CSPE
FML exposed at 78°C to fail. A second CSPE FML sample was brought up to an
elevated temperture (<70°C) over a period of several weeks to allow the
compound to crosslink. Pressure was not exerted until the operating temper-
ature was reached.
5-58
-------
U1
en
TABLE 5-24. SUMMARY OF THE RESULTS OF THE ROOF TUB EXPOSURES
Polymer type
Ethyl ene propylene rubber
FML
number3
8
Wasteb
"HN03-HF-HOAc"
Length of
exposure,
days
2046
Comments
Moderate effects on properties
Ethylene propylene rubber
Polyvinyl chloride
11
Chlorosulfonated polyethylene 6R
Chlorinated polyethylene
77
"Spent Caustic" 2479
"HNOs-HF-HOAc"
"HNOs-HF-HOAc"
"Spent Caustic"
2629
2697
2774
of FML. Lap sealant on seam
under waste had cracked and half
of seam had delaminated.
Moderate effects on properties
of FML. Cracks in fold at top
edge of tub.
Severe effects on properties.
Hardening and loss of flexi-
bility in area above waste.
Loss of properties and swelling
in area under waste. Weather-
cracking along fold at top edge
of liner.
Moderate effects on properties
given crosslinking of polymer.
Severe swelling in areas in
contact with waste. Failure of
reinforcing fabric (nylon).
Blisters and a leak at air-waste
interface.
Moderate effects on properties.
aMatrecon FML serial number; R = fabric-reinforced.
t>Analyses of wastes are summarized in Appendix J.
-------
HYDRAULIC LOAD DEVICE
WITH GAUGE
\
AIR
SUPPLY"
LIQUID LEVEL
SIGHT GLASS
pH
RECORDER
SANO
LEACHATE
RECIRCULATION
PUMP
-HEAT TRANSFER
COILS
PERFORATED
"PLATE PRESS
THERMOCOUPLES
T£ST LINER
-DRAIN
Figure 5-22.
Schematic of accelerated aging column. (Source:
Mitchell and Cuello, 1986, p 19).
After exposure, the FML samples were tested for analytical and physical
properties. The analytical tests were selected specifically for the partic-
ular type of FML in order to determine whether the type of degradation to
which that particular polymer was prone had occurred. For example, the HOPE
samples were tested by differential infrared transmission analysis (to detect
any carbonyl formation), by DSC (to detect changes in crystal 1inity), and by
gel permeation chromatography (to determine molecular weight averages). The
results of the DSC determination indicate that the accelerated test at 78°C
appears to have affected the degree of crystallinity, as is shown in Table
5-25. The results of the molecular weight determinations were inconclusive.
It should be noted that all samples were allowed to dry before physical and
analytical testing.
5.4.1.6 Exposure in Pouch Tests--
The pouch is test described in Chapter 4 (Section 4.2.2.4.1) in the dis-
cussion of the permeability of FMLs and in Appendix D. This test simulates
some of the conditions that an FML might encounter as a liner in a waste
storage or disposal facility (Haxo and Nelson, 1984; Haxo et al, 1982, 1984,
and 1985b). It appears to be not only a means of assessing the permeability
of FMLs but also a means of assessing the durability of FMLs in contact
with wastes. The pouch can be filled with a waste liquid or leachate and the
test can be allowed to run for extended periods of time after which the pouch
is dismantled, the contained fluid weighed and analyzed, and the pouch walls
analyzed and tested for physical properties.
Only pouches fabricated
plastic FMLs can be tested
from thermoplastic and semicrystalline thermo-
by this procedure because of the difficulties
5-60
-------
Involved in making adequate narrow-width seams with cross!inked FMLs. The
pouch test depends on the preparation of leak-free pouches. A seam should
not allow liquids to leak through it (e.g. through pinholes at the edge of
the seam), thereby by-passing the membrane and resulting in a high trans-
mission value.
TABLE 5-25. RESULTS OF DSC ANALYSES OF VIRGIN
AND AGED HOPE FML SAMPLES
Sample
Virgin
18°C
47°C
76°C
Depth, ym
18
36
51
77
33
51
74
97
18
36
53
71
89
107
127
20
41
58
76
23
38
53
74
AHf, cal/g
35.51
35.61
35.69
36.14
34.39
35.24
35.96
35.29
36.40
36.49
36.31
36.57
36.88
36.23
37.00
37.87
39.00
39.19
39.14
37.18
36.99
37.74
37.60
Crystallinity, %
51.9
52.1
52.2
52.8
50.3
51.5
52.6
51.6
53.2
53.3
53.1
53.5
53.9
53.0
54.1
55.4
57.0
57.3
57.2
54.4
54.1
55.2
55.0
aSource: Mitchell and Cuello, 1986, p 15.
The driving force for the movement of a given constituent through the
pouch wall is its relative concentration on both sides of the wall. Each
constituent in a mixture will tend to move through the pouch wall from a
higher concentration of the specific species to a lower concentration of that
species. For example, immersing a pouch filled with a waste liquid in DI
water creates a significant concentration difference that will cause water
to move into the pouch and constituents of the contained waste liquid which
are soluble in the pouch wall to move out of the pouch into the outer water
5-61
-------
where the concentration is lower. These effects are illustrated schemati-
cally in Figure 5-23 for a pouch filled with an aqueous waste or test liquid
and immersed in water.
CONDUCTIVITY
Figure 5-23.
Pouch assembly showing the movement of constituents during the
pouch test. In the case illustrated by this drawing, the pouch
is filled with an aqueous waste or test liquid and immersed
in deionized water. Arrows indicate the flow of specific
constituents.
5.4.1.6.1 Tests of FML pouches containing MSW leachate—The pouch test
was used to assess the permeability of six polymeric FMLs to MSW leachate
(Haxo et al, 1982). An analysis of the leachate placed in the pouch is pre-
sented in Table 5-26. The results of the tests are summarized in Table 5-27.
TABLE 5-26. CHARACTERISTICS OF LEACHATE IN POUCHES
Property
Total solids, %
Total volatile solids, %
Chemical oxygen demand, g L
Total volatile acids, g L~l
pH
Conductivity, ymho cm~l
Value
2.0
1.1
35.7
15.2
5.15
11,500
Source: Haxo et al, 1982, p 98.
5-62
-------
TABLE 5-27. TESTS OF FML POUCHES9 FILLED WITH MSW LEACHATE
Transmission of Water and Ions Through Pouch Walls
Original values
Polymer
CPE
ELPO
T PEL
en
CO
PVC
PVC
PVC
Blank
FML
number
77
36
75
11
17
59
...
Conduc-
tivityb
pHb ymho cm~l
5.7
5.1
4.0
5.8
5.0
5.7
5.5
5.2
4.3
20.5
6.0
13.3
5.9
1.33
Weight of
filled bag,
g pHb
170.91
142.63
112.25
166.88
138.28
170.14
...
5.8
5.0
3.5
4.4
2.9
3.8
5.7
Values at 70 days
Conduc-
tivityb
ymho cnr*
29.7
9.82
73.0
30.9
310.1
61.5
1.75
Values at 500 days
Weight
increase0,
g pHb
1.68
-0.07
0.58
0.41
0.33
0.97
...
6.5
4.5
6.4
6.0
2.8
6.3
4.3
Conduc-
tivityb
ymho cm~l
124.0
17.8
50.0
32.0
325.0
23.2
11.6
Weight
increase0,
g
4.74
0.22
2.95
1.12
1.37
1.21
...
aArea of each pouch exposed to MSW leachate was approximately 560 cm2; each pouch contained 100 mL
of MSW leachate.
and conductivity of water outside the pouches containing MSW leachate.
cWeight increase of pouches containing MSW leachate.
Source: Haxo et al , 1982, p 99.
-------
After 500 days of exposure, test results indicated that there was
movement through the FMLs by both the water and the dissolved constituents of
the MSW leachate. An increase in electrical conductivity occurred, indicat-
ing potential permeation of ions from the leachate into the deionized water.
The odor of butyric acid in the outer water indicated the transmission of
this constituent of the leachate. There was an increase in the weight of
the pouches containing leachate, indicating transmission of water into the
pouches. Of the six FMLs tested, the ELPO yielded the lowest transmission
of water and dissolved components, and the PVC 17 appeared to be the most
permeable.
5.4.1.6.2 Tests of FML pouches containing hazardous waste liquids — In
pouch tests run with actual hazardous wastes (Haxo et al, 1985b),a total of
56 different FML-waste combinations, including 11 different FMLs and 10
different waste liquids, were tested. Selected results of these tests are
summarized in Tables 5-28 through 5-30, which present data for the following:
- Exposure times in number of days that the individual pouches were in
test (Table 5-28).
- Electrical conductivity of the outer water in the pouch assembly at
the conclusion of the tests or before any leaks were noted (Table
5-29).
- Change in weight of the waste in the pouches at the conclusion of the
tests (Table 5-30).
Analyses of the wastes used in this study are presented in Appendix J.
As these tests were exploratory in nature, only one pouch was tested for
each liner-waste combination with the exception of the ELPO pouches contain-
ing the alkaline waste "Slop Water." Pouches were removed from test either
after the pouches failed (i.e. broke), or after an arbitrary prolonged
exposure. Many pouches failed in the seams. Even though some of the seam
failures were related to exposure, these failures are indicative of the
problems involved in fabricating the pouches and do not necessarily reflect
on the seaming techniques used by manufacturers, fabricators, or installers,
whether in the factory or in the field.
The results of these tests indicate the range of responses among the
different FMLs to a single waste and with the same FML to the different
wastes. For example, of the pouches containing the acidic wastes, the ELPO
pouches exhibited the lowest transmission of water (as determined by change
in weight of the pouch contents at the end of test; see Table 5-30) and the
lowest transmission of ions into the outer water (Table 5-29); however, among
the pouches containing the alkaline "Slop Water," the ELPO pouches had the
highest or second highest transmission rates to both water and ions.
To give an example of a complete test, the results of testing the
pouches containing the highly alkaline wastewater "Slop Water" are discussed
in detail in the following paragraphs.
5-64
-------
TABLE 5-28. POUCH TESTS OF POLYMERIC FMLS WITH DIFFERENT WASTE LIQUIDS
Exposure Time in Days
CT)
en
Acidic
"HMO?- Alkaline
Pouch
Polymer
Chlorinated
polyethylene
Chlorosulfonated
polyethylene
Elasticized poly-
olefin
Polybutylene
Polyethylene,
low-density
Polyvinyl chloride
Number3
86 (22)
6R (31)
55 (35)
85 (33)
36 (22)
98 (8)
21 (10)
17 (20)
19 (22)
88 (20)
93 (11)
"HFL"
(W-10)
1895
• • *
1895
1895
1895
1885
1895
...
1767
<1648>
HF-
HOAc"
(W-9)
1887
• • *
• * •
1887
1887
625
<552>
...
* * •
1887
1887
...
"Slop
Water"
(W-4)
625
<65>t>
2516
790
<753>
1725<*
2516
...
* * *
930
<872>
625
<65>
...
"Spent
Caustic"
(W-2)
2420
2468
2420
2468
...
• • *
2420
2468
...
Waste liquid
Indus-
trial
"Basin "Lead
F" Waste"
(W-16) (W-14)
1953 !'.'.
1903 1354
<277>
1952 c
1953
1357
<227>
1952 c
• • * • * •
* • • • • •
Oily
"Oil
"Slurry Pond
Oil" 104"
(W-15) (W-5)
1485
1494
1485
c 1485
1847 1485
<1734>
1494
1484
C 1485
• * • • • •
248
Pest-
icide
"Weed "Weed
Oil" Killer"
(W-7) (W-ll)
1896
...
1896 2250
1896 2250
1896
1882
1775 2250
* * • • • •
1497
<62>
aMatrecon FML number and thickness in mils (in parentheses).
''Number in brackets <> is the number of days pouch was monitored before a rise in electrical conductivity or
a significant loss in weight, i.e. a possible leak, was noted.
cStill in test as of February 26, 1985.
dAfter first pouch swelled and broke at a seam, a second pouch was put into test to confirm results obtained
on first pouch.
-------
TABLE 5-29. POUCH TESTS OF POLYMERIC FMLS WITH DIFFERENT WASTE LIQUIDS
Electrical Conductivity (in ymho/cm) of Outer Water at Conclusion of Test or Before Leakage from Pouch3
en
i
01
Waste liquid
Acidic
Pouch composition
Polymer
Chlorinated
polyethylene
Chi orosulfonated
polyethylene
Elasticized poly-
olefin
Polybutylene
Polyethylene,
low-density
Polyvinyl chloride
Numberb
86 (22)
6R (31)
55 (35)
85 (33)
36 (22)
98 (8)
21 (10)
17 (20)
19 (22)
88 (20)
93 (11)
"HFL"
(W-10)
562
* • •
* » •
68
187
655
545
285
...
595C
"HN03-
HF-
HOAc"
(W-9)
5900
* * *
• • *
3600
86
440
...
...
3200
4600
...
Alkaline
"Slop
Water"
(W-4)
270C
* • •
• » * *
2240
10,800C
85006
2280
...
...
14.70QC
235C
...
"Spent
Caustic"
(W-2)
150
* • *
* * •
40
14
50
• • *
* * •
1300
165
* • *
Indus-
trial
"Basin
F"
(W-16)
...
* • *
3150
...
87
240
220
33C
165
. ..
...
Oily
"Oil
"Lead "Slurry Pond
Waste" Oil" 104"
(W-14) (W-15) (W-5)
191
310
320
...
12C 85d 140
373d 5?c 130
* * • • • * i -3LJ
330
33d 59C 49
... ... ...
6C
"Weed
Oil"
(W-7)
470
* * •
...
55
9
51
482
62C
• • *
54C
Pest-
icide
"Weed
Killer"
(W-ll)
* • •
• • *
...
86
80
...
• * •
51
• * *
...
aE1ectrical conductivity of the deionized water placed in the outer bags was approximately 5 pmho/cm. Reported
values of the conductivity of the liquids in the outer bags, in some cases, may be maximum values before
conclusion of test as the liquids in some of the bags were either diluted with or replaced by deionized water.
The lengths of the various exposures are presented in Table 5-28.
t>Matrecon FML number and thickness in mils (in parentheses).
cpouch failed and waste liquid mixed with the liquid in the outer bag. Reported datum is the electrical con-
ductivity of the outer water at the last monitoring before a leak was noted. See Table 5-27 for length of
exposure before leakage was noted.
dSti11 in test. Reported datum is the electrical conductivity of the outer water as of February 26, 1985,
after 2223 days of exposure.
eAfter first pouch broke at a seam, a second pouch was placed in test to confirm results obtained on first
pouch. Reported datum is conductivity measurement made after 1678 days of test. At that time, the liquid in
the outer bag was replaced with deionized water. Conductivity at end of test (at 1725 days) was 310 umho/cm.
-------
en
i
CTl
TABLE 5-30. POUCH TESTS OF POLYMERIC FMLS WITH DIFFERENT WASTE LIQUIDS
Weight Change (in Grams) of the Waste Liquid in the Pouches as Measured After Pouches were Dismantled
Acidic
Pouch
Polymer
Chlorinated
polyethylene
Chlorosulfonated
polyethylene
Elasticized poly-
olefin
Polybutylene
Polyethylene,
low-density
Polyvinyl chloride
Number3
86 (22)
6R (31)
55 (35)
85 (33)
36 (22)
98 (8)
21 (10)
17 (20)
19 (22)
88 (20)
93 (11)
"HFL"
(W-10)
5.9
• * *
...
0.0
0.7
1.3
4.3
4.3
. ..
9.8b
"HNOi- Alkaline
HF- "Slop "Spent
HOAc" Water" Caustic"
(W-9) (W-4) (W-2)
98.7 27b 22.4
• •• •*• ••*
46.6 22.2 13.0
1.4 209.8° 4.9
245. 8C
0.8b 18.1 7.7
... ... ...
21.0 152.4b 68.6
35.8 2.5b 62.4
Waste liquid
Indus- Oily
trial "Oil
"Basin "Lead "Slurry Pond
F" Waste" Oil" 104"
(W-16) (W-14) (W-15) (W-5)
-8.8
*•• ••* ••• ™ A 0 »*r
5.3 -21.3
•*• *•• ••• *••
3.3 -0.9b -0.5d -15.2
5.4 -1.3d -0.2b -5.7
11.5 -8.0
7.5b -1.3
31.8 -1.2d 0.5d -0.3
• * • ••* ••• •••
0.0b
"Weed
Oil"
(W-7)
1.9
...
...
0.0
-0.8
0.8
-0.5
-0.2b
.. .
2.2b
Pest-
icide
"Weed
Killer"
(W-ll)
...
• * •
...
-1.4
-1.8
...
• • *
-2.5
...
...
aMatrecon FML number and thickness in mils (in parentheses). See Table 5-28 for exposure times.
DPouch failed and waste liquid mixed with the liquid in the outer bag. Reported datum is weight change
the filled pouch at last monitoring before a leak was noted.
cSecond pouch placed in test after first pouch swelled and broke at a seam.
dStill in test. Reported datum is weight change as of February 26, 1985, after 2223 days of test.
of
-------
Pouches fabricated from six different FMLs (CPE 87, CSPE 85, ELPO 36,
PB 98, and PVCs 19 and 88) were tested with the highly alkaline wastewater,
"Slop Water" (W-4). Premature seam openings occurred in four of the pouches
including the first ELPO.
A leak in the seam of the first of two ELPO pouches (P30A) was noted
at 790 days of exposure after the pouch had become bloated due to its large
increase in weight. At approximately 300 days, the rate at which this pouch
had changed in weight had increased, indicating a change in the permeability
of the pouch walls. Because of this apparent change in permeability, a
second pouch was placed in test to verify the behavior of the first pouch.
The second pouch (P30B) behaved similarly; it showed no significant increase
in weight until it had been in test for about 300 days, and then, even though
it did not increase at as great a rate as the first pouch (P30A), it began to
increase significantly in weight. Both pouches showed a similar rise in the
electrical conductivity of the water outside the pouch after reaching 1000
pmho cm"1 at approximately 300 days of test. Again, the second pouch
(P30B) did not show as steep a rate of increase in electrical conductivity as
the first pouch (P30A). The results of monitoring the weight of the two
pouches and the pH and electrical conductivity of the liquids in which they
were immersed are presented in Figure 5-24. The second pouch (P30B) was
dismantled after 1725 days of test because it had gained so much weight and
had swelled to the point that bursting seemed imminent. The pouch waste was
weighed, and both the pouch waste and the liquid in the outer bag were
measured for pH and electrical conductivity. Measurements made on the two
ELPO pouches, including those made at the time of dismantling, are presented
in Table 5-31.
The highly alkaline waste liquid appeared to interact slowly with the
ELPO wall. The effect became apparent during monitoring after 300 days of
exposure when the rates of transmission of water into the pouch and the rate
of increase in electrical conductivity of the outer water rose dramatically.
After the pouches were dismantled, the pouch walls were analyzed and tested
for physical properties. The results of these tests indicated that losses
had occurred in the tensile strength, elongation at break, and tear re-
sistance.
The CSPE 85 and PB 98 pouches containing the "Slop Water" wastewater
reached almost seven years of exposure without failure before they were dis-
mantled (Table 5-28). The wastewater content in both pouches increased ap-
proximately 20 g, indicating that water had permeated into the pouches (Table
5-30). The pouch walls also increased in weight: the CSPE pouch increased
by 17% in weight and the PB pouch increased 3%. The outer water of both
assemblies had an electrical conductivity of approximately 2200 umho/cm, as
is shown in Table 5-29, indicating that the walls of both pouches allowed
equal permeation of ions, probably H+ and OH~ ions. The PB maintained
its physical properties but developed a number of small blisters, approxi-
mately 1 mm in size. The CSPE softened slightly and, while it maintained its
tensile strength, decreased in elongation at break, and increased in modulus.
The changes in tensile and tear properties are probably a result of cross-
linking of the polymer during exposure combined with absorption of water.
5-68
-------
Outer liquid »
replaced with
Dl water at 1682 d
Dl water added
to outer bag
at 1155 d
200 400
600 800 1000 1200 1400 1600 1800
Time, days
a. Change in weight of filled pouches.
200 400
600 800 1000 1200 1400 1600 1800
Time exposed, days
b. pH of outer water.
Outer liquid «
replaced with
Dl water at 1682 c
Dl water added -*•
to outer bag
at 1155d
200
600
800 1000
Time, days
1200 1400 1600 1800
Figure 5-24.
c. Electrical conductivity of outer water.
Monitoring data for ELPO pouches (P30A and P30B) containing the
highly alkaline waste, "Slop Water" (W-4).
5-69
-------
TABLE 5-31. MEASUREMENTS ON THE TWO ELPOa POUCHES
FILLED WITH "SLOP WATER" WASTE (W-4)
Parameter
Exposure time, days
Pouch liquid
PH
Electrical conductivity, ymho/cm
Outer water
pH
Electrical conductivity, ymho/cm
Filled pouch, original weight, g
Final weight, g
Change in weight, g
Empty pouch, original weight, g
Final weight, g
Change in weight, g
Pouch contents, change in weight, g
Original area of pouch, cm2
Final area of pouch, cm2
Change in area, cm?
Rates of water transmission
into pouch6, g/m^-d
Calculated by correlation from
increase in pouch weight data^
Initial (0 - 300 d)
Intermediate (300 - 1200 d)
Final (1200 - end)
Overall (0 - end)
Calculated from Increase
in pouch liquid weight
Overall (0 - end)
Final (300 - end)9
Analysis of pouch wall
Volatiles, X
Extractables, %
Original
properties
• • •
13.1
129,000
7.0
1.3
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
0.15
5.50
Exposed
P30A
753&
11.9
105,000
12. QC
90.00QC
215.13
428.72
+213.59
27.62
31.45
+3.83
+209.76
486
521
+35
0.199(10)
9.005(8)
N/A
5.527(18)
5.732
7.779
10.85
2.09
pouch
P30B
1725
13.2
84,000
8.9d
31Qd
98.45
346.94
+248.49
26.25
28.98
+2.73
+245.76
374
383
+9
0.215(11)
5.651(3)
2.900(16)
4.125(30)
3.809
4.526
8.47
2.85
a«atrecon FML No. 36; 20-mll thickness.
noted during monitoring of pouch at 790 days. Pouch removed from
test at that time.
cPrior to seam leak the electrical conductivity of the outer liquid was
14,000 pmho/cm and the pH was 12.4.
dThe outer water had a pH of 10.3 and an electrical conductivity of
8500 pmho/cm before It was replaced with 01 water on day 1682.
eBased on original area of pouch.
^Number of data points given in parentheses.
9Calculated by subtracting an increase in weight of a filled pouch at
approximately 300 d from the total change in weight of the pouch contents.
At 204 days, P30A had gained 2.2 g. At 287 days, P340B had gained 2.32 g.
5-70
-------
Of the other three pouches tested with the "Slop Water" wastewater, the
CPE 86 and the PVC 88 pouches began to leak at the seams after 65 days of
test but were not removed from exposure until after 625 days. The PVC 19
pouch broke at a seam after 872 days of test. Before it had broken, the
pouch had become bloated and had increased significantly in weight, and the
liquid outside the pouch had increased significantly in electrical con-
ductivity, probably due to migration of OH~ ions out of the pouch and H+
into the pouch (Tables 5-29 and 5-30). Testing and analysis of the wall
material showed that the FML had decreased in extractables and had increased
in modulus and tensile strength. The changes in properties of the two PVC
materials indicate significant loss of plasticizer after exposure to the
"Slop Water" wastewater.
5.4.1.6.3 Overview of pouch test results—The results of the pouch
tests that have been reported in this section and in Section 4.2.2.4.1 have
been somewhat inconsistent indicating the problems with performing this test,
particularly with fabricating the pouches. The test was developed both to
study the permeation of constituents of waste liquids and test liquids
through polymeric membranes, under conditions that simulate some of the
conditions of exposure and to study one-sided exposure of FMLs to waste
liquids and other test solutions. The particular constituents included:
- Water.
- Ionic constituents.
- Organic constituents, e.g. oils.
The results of testing the pouches indicate the movement of water
through the pouch walls, as is shown by the increase in weight of many of the
pouches. As is discussed in Section 4.2.2.4.1, PVC pouches containing Lid
solutions increased in weight in differing amounts, depending on the con-
centration of the LiCl in the pouch and the specific PVC FML, thus indicating
the importance of the concentration gradient as a driving force for perme-
ation through a membrane. The pouch tests with the highly acidic and highly
alkaline waste liquids also showed significant transmission of water into the
pouches. Transport through an FML is described in more detail in Chapter 3.
The pouch tests with solvents, also discussed in Section 4.2.2.4.1,
present different problems with respect to the permeability of water. The
pouches filled with acetone or xylene in DI water showed a negative trans-
mission rate indicating the movement of acetone or xylene out of the pouches
rather than any water movement into the pouches. The pouches with 50:50
acetone:water showed an outward movement of acetone when immersed in DI water
and inward movement of acetone when immersed in acetone.
Taken as a whole, these results indicate that a pond lined with an FML
placed in a moist, perhaps saturated, environment in which the water is
relatively pure would receive water from the environment outside the pond.
Such would be true even if the liner contained no holes or breaks. In the
diffusion process, each constituent migrates through the FML as an independ-
ent molecular species.
5-71
-------
In pouch tests with waste liquids that were highly acidic or highly
alkaline, some increases in EC were observed in the water in the outer
bags, indicating high concentrations of ions. Close inspection of the
pouches after disassembly indicated some weak seams and damage to some of the
FMLs at the corners, particularly in the case of fabric-reinforced FMLs;
however, those pouches that were well made and had good seams yielded little
increase in the EC of the water in the outer bags and thus little, if any,
transmission of ions. Overall, the results of the pouch tests indicate
that polymeric FMLs are probably highly resistant to ion transmission, with
the possible exception of H+ and OH~ ions. The appearance of high EC in
an outer bag in a relatively short time probably indicates that liquid from
inside the pouch has entered the water in the outer bag through a hole that
developed at a seam or through a pinhole that developed in the pouch wall.
It is recognized that the absorption of C0£ from the air results in an
increase in the EC of the water as well as a decrease in the pH of the water,
and that the migration of soluble compounding ingredients out of the pouch
walls or residuals from FML manufacture may also have affected EC measure-
ments.
The pouch tests indicated that organic liquids would permeate the FMLs,
although the rate varied greatly depending on the solubility of the permeat-
ing species in the FML and the difference in chemical potential of the
permeating species on the two sides of the FML, as is discussed in Chapter 3.
The results of pouch tests discussed in Section 4.2.2.4.1 showed that acetone
and xylene permeated the walls of the pouches when the pouches were placed in
DI water. The acetone permeated the walls and dissolved in the outer water;
the xylene permeated but, because it is not soluble in water, rose to the
surface. When the pouches with the acetone and xylene were placed in the
same solvents, the movement was into the pouch where the solvent contained
dissolved constituents, either organic dyes or water.
Pouch tests with waste liquids containing oils indicated that the oils
permeated the walls of the pouches resulting in a film of oil being formed on
the outside of the pouches. Since the oils were not soluble in water, they
tended to remain on the surface of the pouches and stop further movement of
oils through the pouch walls. If the oils had been soluble in the water, the
concentration of the oil on the downstream surface of the FML would have
been lower and migration of the oil would have continued.
The pouch test appears to be a feasible method of qualitatively assess-
ing the permeability of FMLs over long periods of time and of assessing the
durability of FMLs in contact with waste liquids or test liquids. Of parti-
cular interest were results indicating changes in the permeability of an FML
after prolonged exposure, e.g. the results of the ELPO pouches tested with
the "Slop Water" waste discussed in Section 5.4.1.6.2. Maintaining an FML
in a moist condition appears to be an important element in assessing the
long-term permeability of an FML that may slowly become affected by a waste
liquid. The difficulties with the pouch test include the prolonged exposure
time that may be required and the problems with fabricating hole-free pouches
with seams that will maintain the integrity throughout the exposure. In
addition, test results with volatile organics depend on the rate at which
5-72
-------
volatiles are allowed to escape from the test system, i.e. from the container
in which the pouch is immersed.
5.4.1.7 Permeability of FMLs to Mixtures of Organics
and Aqueous Solutions—
Most leachates and waste liquids are complex dilute aqueous solutions of
organic and inorganic chemical species. In order to contain these solutions,
it is necessary to know the magnitude of the permeation of these species in
mixtures through the FMLs. Each species has its own solubility and diffusion
rate through a polymeric FML when tested individually; however, when in
mixtures, it is anticipated that there may be interaction between the compo-
nents of the mixture and the FML and that this interaction may affect the
diffusion rates and thus the transmission of the different species. The
following subsections present the results of experimental studies on the
permeability of FMLs to mixtures of organics and aqueous solutions containing
organics.
5.4.1.7.1 Permeability to mixtures of organics—Two studies have been
performed to measure the permeation of a mixture of solvents through an FML.
To simulate a mixture of waste solvents leaking from a drum onto an FML,
August and Tatsky (1984) measured the transmission rates of each of six
solvents from an equivolume fraction mixture through a 40-mil HOPE FML. The
apparatus used by August and Tatsky consisted of two compartments separated
by the FML. The upper compartment contained the solvent mixture, and the
lower was partially evacuated. In this experiment, the composition of the
liquid mixture was held constant. A support screen was placed under the FML
in the lower compartment because of the vacuum pressure. The permeating
vapors were collected in a cold trap and then analyzed by gas chromatography.
The results are presented in Table 5-32. The data show the high rates of
transmission for the two chlorinated solvents and the great difference in the
rates among the solvents.
TABLE 5-32. PERMEATION RATES OF THE COMPONENTS OF
A MIXTURE OF ORGANICS THROUGH A 40-MIL HOPE FML
Permeation rate,
Organic g m~2 d"l
Trichloroethylene 9.4
Tetrachoroethylene 8.1
Xylene 3.0
Isooctane 0.8
Acetone 1.4
Methanol 0.7
Total 23.4
Source: August and Tatzky, 1984, p 166.
5-73
-------
Matrecon has performed a similar experiment in which the transmission
rates of the components of a solvent mixture containing equal volumes of
methanol, methyl ethyl ketone (MEK), 1,1,1-trichloroethane (TCA), toluene,
and n-heptane through a 20-mil FML (ELPO 172) were maintained. This testing
was performed in accordance with a procedure based on ASTM E96, Inverted
Water Method (Procedure BW). Circular specimens of ELPO 172 were mechanical-
ly clamped onto the mouths of aluminum cups partially filled with the solvent
mixture (see discussion of solvent vapor permeability in Section 4.2.2.4.1).
The cups were stored in an upright position so that only the vapors contacted
the FML specimens. The transmission rates were monitored by headspace gas
chromatography. Table 5-33 lists data obtained from averaging test results
from triplicate cells. The following observations were made:
- All components of the mixture diffused through the FML simultaneously,
but at different rates.
- The total transmission rate and the rates for the individual solvents
varied significantly as the composition of the liquid phase changed.
The SVT test cups were not infinite reservoirs and the solvent loss
rates declined steadily with time as the more readily transmissible
components were lost.
The results of these two studies indicate that strong selective permeability
causes very different permeation rates for components of mixtures.
TABLE 5-33. TRANSMISSION OF SOLVENT MIXTURES
THROUGH A 20-MIL ELPO FMLa
Weight, % of solvent remaining
Time, h Methanolb MEK n-Heptane TCA Toluene Totaic
0
22
70
17.6
il7.3
ae.s
18.0
16.6
13.8
15.2
12.6
7.9
29.8
27.0
21.8
19.3
17.2
13.2
100.0
90.8
73.7
aMatrecon FML No. 172.
methanol loss was below the analytical detection limit of
the GC column. These data are based on a limiting value, the
lower detection limit.
cThe component values do not add exactly to the "total" value;
see footnote "b". Additional errors were generated by manually
integrating the loss rate data using the trapezoidal method.
The maximum error is 2.3%.
5-74
-------
5.4.1.7.2 Permeability to aqueous solutions of organics—Leachates
containing smallamounts of organics may contact an FML.However, little is
known about how the rate of permeation of an organic from an aqueous solution
(i.e. a leachate) compares with the rate of permeation of the same organic in
a concentrated form through the same FML. To simulate the permeation of a
leachate containing organics through an FML, August and Tatzky (1984) also
studied the permeation of dilute aqueous solutions of organics through a
variety of FMLs using the same equipment described in the previous sub-
section. The results of measuring the permeation rate of a 0.05 weight
percent aqueous solution of toluene through various FMLs are presented in
Figure 5-25. The permeation rates of various pure organics and dilute
solutions (0.1 to 0.001 weight percent) of the same organics through a 40-mil
HOPE FML are compared in Figure 5-26. The data show that the permeation from
a dilute solution of an organic can be substantially higher than what would
be expected from the difference in concentration. For example, even though
the ratio between the concentrated toluene and the dilute solution was
1000:1, the ratio between permeation rates through the HOPE was 20:1. These
results indicate that significant quantities of an organic can permeate
through an FML due to selective permeation, even when the organics are
present in a leachate at a very low concentrations.
In a separate experiment performed by Haxo et al (1988), a three-
compartment closed apparatus was used to assess the permeation of organics
from dilute aqueous solutions through polymeric FMLs. The test apparatus,
shown schematically in Figure 5-27, can be divided into seven zones, which
are listed in Table 5-34. FML specimens separate the three compartments
(Zones 2 and 5). An aqueous solution containing organics partially fills the
middle compartment (Zone 4), and DI water can be placed in the bottom com-
partments (Zone 7). The three compartments are clamped tightly together.
Thus, the organics can either volatilize into the airspace above the solution
and then, permeating through the top FML specimen, enter the top compartment
or the organics can permeate through the lower FML specimen and into the
bottom compartment. The covers of one end of each of the top and the bottom
compartments were welded to the walls to avoid potential loss of volatiles.
The only potential leaks were those that might occur at the flanges between
which the FML specimens that separated the three compartments were mounted.
Ports with Teflon silicone rubber septums were incorporated in each of the
three compartments for use in withdrawing samples for GC analysis from the
aqueous and airspace zones. The two FML zones can be analyzed by GC after
the apparatus is dismantled.
The three-compartment apparatus simulates the configuration of a covered
landfill as follows:
- The airspace in the top compartment is like the airspace over a
"cover" liner. The FML specimen between the top and middle compart-
ments is like a "cover" liner.
- The airspace in the middle compartment simulates the headspace above a
waste liquid, and the dilute solution containing organics serves as
the waste liquid. The FML specimen between the middle and bottom
compartments simulates the service conditions of a bottom liner.
5-75
-------
en
i
OJ
E
O)
05
O
W
O)
.0
0)
03
tr
c
g
T3
0>
E
05
Q_
10
0.1
0.01
10'
E
O)
jiT
8
O)
o
c
.g
c5
CD
E
0>
Q.
HOPE.
1 mm
(40 mil)
Figure 5-25.
PVC, PVC. ECB, CPE-PE. EPDM.
1mm 2mm 2.6mm 1.5mm 1.8mm
(40 mil) (80 mil) (100ml) (60 mil) (70 mil)
Permeation rates of 0.05 weight
percent aqueous solutions of
toluene through various FMLs.
ECB = ethylene copolymer with
bitumen. (Based on August and
Tatsky, 1984, p 167).
10
-1
100%
I ) Concentrated
Diluted
100%
o.i
weight
100%
0.05
weight
100%
0.02
wight
0.001 weight %
Trichloro- Toluene Xylene Iso-octane
ethylene
Figure 5-26.
Permeation rates of concen-
trated and dilute solutions of
various organics through a 1-mm
(40-mil) HOPE FML. (Source:
August and Tatsky, 1984, p
166).
-------
Airspace
Septum
Aqueous solution of
of organics
Figure 5-27. Schematic of the three-compartment test apparatus used in the
study of the distribution of organics between water, air, and
an FML and the permeation of organics through an FML. Inside
diameter of each compartment was 4 inches. (Based on Haxo et
al, 1988).
5-77
-------
- The airspace and the deionized water in the bottom compartment simu-
late, respectively, pore spaces in the soil and the groundwater.
TABLE 5-34. ZONES IN THREE-COMPARTMENT TEST APPARATUS
Zone
Compartment
Description
Volume, mL
1 Top
2 Barrier between
top and middle
3 Middle
4 Middle
5 Barrier between
middle and bottom
Airspace above "cover" 806
"Cover" FML (33-mil LLDPE): ~7
Area exposed to solution
Airspace above aqueous solution 306
containing organics
Dilute aqueous solution containing 500
organics
"Bottom liner" (33-mil LLDPE): -7
Area exposed to solution
6
7
Bottom
Bottom
Airspace below "bottom liner" FML
Deionized water
Total
506
300
2,432
Source: Haxo et al, 1988.
The configuration of the zones within each compartment can be modified
to assess double liners and various auxiliary materials, such as covers,
geotextiles, and drainage materials.
In an experiment to assess the distribution of organics between water,
air, and an FML and the diffusion and the permeation of organics through an
FML, a dilute aqueous solution of toluene and trichloroethylene (TCE) was
placed in the middle compartment of the test apparatus. Both of these
organics are commonly found in leachates and are easily identifiable and
trackable by GC analysis. Information on these two organics is presented in
Table 5-35. Both are identified as volatile contaminants by the Environ-
mental Protection Agency. An LLDPE FML (Liner No. 284) was used in this
experiment to separate the three compartments. Data on this FML are pre-
sented in Table 5-36.
In this experiment, seven zones were incorporated in the three compart-
ments (Table 5-34). Zone 4 was filled with 500 ml DI water and spiked with
191 mg each of toluene and TCE to yield concentrations of 382 mg each per L
of water. The five zones containing water or vapor were sampled and analyzed
by GC periodically to assess the changes in concentrations in these zones.
5-78
-------
After 256 hours, when the concentrations appeared to remain constant, the
apparatus was dismantled and the FML samples were removed and analyzed by
headspace GC to determine the concentrations of the organics in the FMLs.
Also, analysis was performed separately on the FML in the flange area, as
well as the area that contacted the vapor. The results of the analyses of
samples taken at 24, 96, and 256 hours are reported in Table 5-37.
TABLE 5-35. ORGANICS USED IN THREE-COMPARTMENT
APPARATUS EXPERIMENT WITH DILUTE AQUEOUS SOLUTIONS
Property
Purity, %
Molecular weight, %
Density at 20°C, g cnr3
Specific volume, cm3 g'1
Boiling point, °C
Vapor pressure at 25°C, mm Hg
Toluene
99.9
92.13
0.866
1.155
110.6
31.96
Trichloroethylene
99.9
131.40
1.476
0.677
87.2
80.30
Solubility parameters3:
•So
6d
-------
flanges. Overall, these results show that the apparatus had come to equi-
librium; they also show the high absorption of organics by the FML. At these
equilibrium conditions, the coefficients of distribution between the LLDPE
FML and water for TCE and toluene were 178 and 120, respectively.
TABLE 5-36. SELECTED PROPERTY VALUES OF A 33-MIL
LLDPE FML (MATRECON FML NO. 284)
Property Value
Thickness, mil 33.4
Carbon black content, % 2.5
Specific gravity of FML 0.927
Density:
FML at 23°C, g/mL 0.924
Polyethylene (calculated by correcting
for carbon black content), g/mL 0.913
Crystallinity, % 36.3
Melting point, °C 119
Source: Haxo et al, 1988, p 68.
The experiments on the distribution of organics from dilute solutions
show that, even at low concentrations in an aqueous leachate, some of the
organics can be highly absorbed by the polymeric FML and can permeate the
liner. The amount and rate of absorption and the transport of these species
through a polymeric FML is a function of such factors as relative solubility
parameters of the FML and the organic, crystal!inity of the FML, and mole-
cular weight and concentration of the organic constituent. A multi-compart-
ment apparatus, such as the one described, appears to be an appropriate and
promising means of assessing the effectiveness of an FML to contain a given
leachate.
5.4.2 Immersion Tests of FMLs
In rubber and plastics technology, the compatibility of polymeric
products being considered for service with a particular solvent or liquid is
commonly tested by immersing samples of the rubber or plastic compound in
that solvent or liquid. In this type of testing the changes in weight,
dimensions, and physical properties can be used to monitor the effects of
immersion. It is, of course, desirable that no changes in the material occur
during service; therefore, changes in dimensions and in properties can
5-80
-------
TABLE 5-37. DISTRIBUTION OF ORGANICS IN THREE-COMPARTMENT TEST APPARATUS SEPARATED BY POLYETHYLENE FMLS
en
i
oo
No.
1
2
3
4
5
6
7
Zone
Description
Ai rspace above
"cover" FMLb
"Cover" poly-
ethylene FMLb
Airspace above
test liquid
Test liquid
Barrier FMLb
Airspace below
FML
"Groundwater"
Total
Fraction ac-
counted for,
Volume,
mL
806
7.02
306
500
7.02
506
300
2,432
%
Start
Amount,
Organic ntg
TCE*
Toluene
TCE
Toluene
TCE
Toluene
TCE
Toluene
TCE
Toluene
TCE
Toluene
TCE
Toluene
TCE
Toluene
TCE
Toluene
0
0
0
0
0
0
191
191
0
0
0
0
0
0
191
191
100
100
of test
At 24
Concen-
tration, Amount,
mg/L mg
0
0
0
0
0
0
381
381
* * *
• • *
* * a
* • •
• * •
• * *
381
381
9.2
7.9
• » •
* * *
12.1
10.1
95
92
• • *
• * •
8.6
1.16
0.75
~o
125.6
111.1
65
58
hours
Concen-
t rat i on ,
mg/L
11.5
9.8
• * •
• • •
39.5
33.0
190
185
• * •
* • *
17.2
2.3
1.5
~o
• » •
• • *
At 96
Amount,
mg
14.1
10.0
• • •
• • •
8.8
8.1
80
80
• * *
• • •
11.9
3.74
6.42
4.57
121
106.4
63
55
hours
Concen-
tration,
mg/L
17.5
12.5
• » •
• • •
29.0
26.5
160
160
* * *
• • •
23.5
7.4
21.4
15.2
• • •
• • •
At end
256
Amount,
mg
12.9
4.8
56.1
60.2
5.97
1.83
22.5
35.7
56.1
60.2
9.87
2.58
13.5
21.4
176.9
186.7
92.6
97.7
of test,
hours
Concen-
tration,
mg/L
16.0
6.0
7,990
8,580
19.5
6.0
45.0
71.4
7,990
8,580
19.5
5.1
45.0
71.4
• • •
• * «
aTrichloroethylene.
bLinear low-density polyethylene FML (Liner No. 284),
Source: Haxo et al, 1988, p 70.
-------
indicate a degree of incompatibility. In some applications, specific changes
in properties of the material limit the serviceability of a product. For
example, a fluid delivered by a rubber hose may cause excessive shrinkage
which could stiffen the hose, or swelling which could restrict the flow in
the hose to such an extent that the hose would no longer be serviceable.
Waste liquids can cause changes in the dimensions and the physical
properties of FMLs; therefore, measuring changes in dimensions and properties
after an immersion test should give an indication of the compatibility
or incompatibility of an FML and a specific waste liquid. Immersion testing,
in which two sides of an FML are exposed to a waste liquid, can function as
an accelerated simulated-service test of an FML in that it simulates the
exposure of an FML in direct contact with a waste. This type of exposure is
without mechanical stress, which can be a significant factor in service
conditions.
This section describes the results of immersion testing that has been
performed on polymeric FMLs. Studies have been undertaken in which FML
samples have been immersed in MSW leachate (Haxo et al, 1982), a range of
hazardous wastes (Haxo et al, 1985b), and a series of test liquids (Haxo et
al, 1988; Bellen et al, 1987; Morrison and Parkhill, 1987). These studies
are discussed in the following subsections.
In general, immersion testing of polymeric products at elevated temper-
atures (e.g. 50°C) has been thought to be an effective way of accelerating
the effects of immersion. However, this form of acceleration is effective
only for specific combinations involving known processes. In other cases,
the effect of the elevated temperature may cause changes in the polymeric
product which do not correlate with service at a lower temperature. Some of
the work reported in this section explores the usefulness of immersion at an
elevated temperature in the compatibility testing of FMLs.
5.4.2.1 Immersion in MSW Leachate--
In conjunction with the simulation testing discussed in Section 5.4.1.1,
samples of polymeric FMLs were immersed in MSW leachate (Haxo et al, 1982).
Only a limited number of FMLs could be exposed in the simulation tests. The
immersion study was undertaken to include a wider range of polymeric FMLs in
the testing program and to develop a correlation between the one-sided
exposure in the simulators and two-sided exposure by immersion. The avail-
ability of the leachate generated by the MSW simulators made it possible to
expose the FML samples in the two exposure tests to the same waste liquid.
Twenty-eight different FMLs of 11 different polymeric types were
selected for immersion testing. The FMLs selected included some that were
already in exposure in the simulators as well as others that had become
available either commercially or on a developmental basis. Three sets of the
28 FMLs were immersed so that specimens could be tested after 8, 19, and 31
months of immersion. No attempt was made to seal the exposed fabric ends of
the fabric-reinforced FMLs that were immersed.
5-82
-------
The immersion system allowed a blend of
simulators to flow slowly through a series of 6-
which the FML specimens were hung. The size of
allow immersion of 8 x 10-in. slab specimens.
which the specimens were hung, were sealed into
Inlets and outlets were also installed in the
leachate. The lids were then welded onto the
used in these tests are presented schematically i
the leachates from the MSW
gal heavy-duty HOPE tanks in
the tanks was sufficient to
Stainless steel hooks, on
the lids of the tank lids.
lids to allow the flow of
tanks. The immersion tanks
n Figure 5-28.
LEACHATEIN
LEACHATE OUT
SPECIMENS
COVER DETAIL
SPECIMENS /
ATTACH TO HOOKS
NOTE:
PLASTIC WELD
SEALS CONTAINER
CROSS SECTION
LEACHATE IN-»
-LEACHATE OUT
POLYETHYLENE TANK
Figure 5-28.
Schematic of HOPE immersion tank, showing method of holding
specimens and the inlet and outlet for the MSW leachate.
(Source: Haxo et al, 1982, p 80).
Initially, the flow of the leachate through the tanks was effected
by gravity feed from a drum containing leachate placed above the tanks.
Problems were encountered with this arrangement; solids precipitated from the
leachate and plugged the system. A Masterflex pump was then installed so
that leachate was delivered at the rate of 14 ml per minute through the
tanks. The supply of leachate recirculated in about 12 days.
Approximately 48 gal of leachate, obtained by blending the output of
the MSW simulators, was introduced into the system every four weeks and a
5-83
-------
similar amount of the used leachate was drawn off. Samples of both the new
and. used leachate were tested at each addition for: pH, chemical oxygen
demand (COD), total solids (TS), total volatile solids (TVS), and total
volatile acids (TVA). The composition of the leachate added to the system
changed little while it was used to expose the FML samples, indicating the
air-tight, anaerobic character of the system. During the initial operation
of the system, the analytical results (Table 5-38) were close to the cal-
culated averages of the leachates from the simulators. In later months,
however, differences developed between the two that may have been caused by
biological contamination of the blended leachate.
TABLE 5-38. ANALYSIS OF LEACHATE USED IN THE IMMERSION SYSTEM*
Leachate added Leachate removed
Property to system from system
PH
Chemical oxygen demand, g L"l
Total
Total
Total
volatile acids, g L~l
solids, %
volatile solids, %
5.27
32.6
11.3
1.70
0.94
5.27
29.0
11.3
1.80
1.00
aSamples were taken on January 31, 1975.
Source: Haxo et al, 1982, p 82.
The tests performed on the FMLs before and after each of the three
exposure intervals were:
- Weight of specimen.
- Dimensions of specimen.
- Tensile properties, in machine and transverse directions, three
specimens per direction, ASTM D412. Testing was performed using a
special dumbbell which features smaller tab ends, a shorter overall
length, and a shorter narrowed test area in comparison with the ASTM
D412 Die C dumbbell.
- Hardness, ASTM D2240.
- Tear strength, in machine and in transverse directions, two specimens
per direction, ASTM D624, Die C.
- Puncture resistance, two specimens, FTMS 101C, Method 2065.
5-84
-------
- Volatiles, Matrecon Test Method 1 (Appendix G).
The range of values for a selection of properties measured on all the
samples from each of the eleven polymer types are shown for 8, 19, and 31
months immersion in Table 5-39. In all cases, the FMLs absorbed leachate,
but the data show that swelling varies both among types of polymers and
within a generic polymer type. The variations within a polymer type result
from both compounding and polymer differences. In some cases, the absorption
appeared to have dropped due to changes in the composition of either the
leachate or the FML (due to plasticizer loss).
The effect of immersion in leachate up to 31 months appears to have a
relatively mild effect on most of the FMLs as is shown for tensile strength
retention versus immersion (Figures 5-29 and 30). Of the 28 FMLs in the
exposure test, 11 increased in tensile, 10 decreased, and 7 remained es-
sentially unchanged. The maximum average retention after 31 months of
exposure was 135% and the lowest was 70%. The effect of immersion on the
modulus (i.e. stress at 200% elongation) of the same materials is shown in
Table 5-40. The PVC FMLs had a small spread in values and retained their
original tensile strength as well as modulus. Overall, the polyolefins, such
as polyethylene, polybutylene, and elasticized polyolefin, exhibited the
lowest swelling and highest retention values.
5.4.2.2 Immersion of FMLs in Hazardous Wastes and Selected
Test Liquids--
Immersion testing of a variety of polymeric FMLs in actual hazardous
wastes and in selected test liquids was performed in conjunction with the
simulated exposure testing discussed in Section 5.4.1.2 (Haxo et al, 1985b).
As the project progressed, many new FMLs became available, including some
based on polymers not being tested in the primary exposure program and some
based on polymers already being tested but of significantly different
composition. Only a limited number of FML-waste combinations could be
tested as liners in the one-sided exposure cells; thus, immersion testing
was performed to increase the number of FMLs being exposed to the hazardous
wastes. In addition, some FML-waste combinations tested in the one-sided
exposure cells were also tested in immersion to develop a correlation
between two-sided exposure testing and exposure as a liner in the test
cells. Altogether, 16 different FMLs based on 11 different polymer types
were exposed to 13 wastes or test liquids.
The wastes and test liquids used in the immersion tests are listed
in Table 5-41. The saturated tributyl phosphate (TBP) solution was included
in the tests because of concern about the effects a solution containing a
small amount of organics might have on an FML. TBP was selected, not only
because of its low solubility in water, but because of its relatively low
volatility and its phosphorous content which could be used as a tracer of the
TBP movement.
5-85
-------
TABLE 5-39. SUMMARY OF THE EFFECTS OF IMMERSION OF POLYMERIC FMLS IN MSW LEACHATE FOR 8, 19, AND 31 MONTHS3
OO
CT>
Polymer type
Butyl rubber
Chlorinated polyethylene
Chlorosulfonated polyethylene
Elasticized polyolefin
Ethyl ene propylene rubber
Neoprene
Polybutylene
Polyester elastomer
Low-density polyethylene
Polyvinyl chloride
Polyvinyl chloride + pitch
Number
of
FMLs
in
tests
1
3
3
1
5
4
1
1
1
7
1
Weight increase, %
8 mo.
1.8
8-10
13-19
0.1
1-21
1-19
0.1
2.0
0.6
1-3
6
19 mo.
3.5
16-18
16-27
1.6
1-12
3-32
0.8
1.9
0.7
1-6
8
31 moTo
25
25-28
19-32
8
8-24
5-88
...
16
3
4-24
14
Tensile strength,
X original
8 mo.
90-97
80-115
82-124
86-94
64-107
69-100C
96-99
99-115
110-180
91-110
92
19 mo.
89-94
81-106
95-132
96-107
86-93
60-102
94-95
52-94
92-149
91-111
88-93
31 mo.
92
78-106
103-138
98-106
94-113
68-105
84-97
81-90
118-161
87-117
101-104
Elongation,
% original
8 mo.
104-106
64-135
97-107
91-92
76-138
82-103c
96-97
101-108
96-181
98-139
109-133
19 mo.
99
76-108
77-94
102
83-146
76-104
96
92-94
67-192
100-129
94-117
31 mo.
90-92
71-103
69-86
96-98
88-138
78-146
86-89
80-96
100-168
79-120
80-103
Change in hardness,
Duro A, points
8 mo.
0
-5 to 1
-20 to -4
0
-1 to +2
-11 to +5
-3
-4
• • *
-2 to +1
-2
19 mo.
0
-8 to -2
-26 to -5
-2
-2 to -1
-12 to +3
-5
-6
...
-6 to +1
+1
31 mo.
-1
-11 to -1
-21 to -3
-1
-3 to t5
-18 to +4
-3
-3
...
-6 to +3
+1
aRanges of retention values for tensile strength and elongation are lowest and highest averaged values obtained for either machine or transverse direc-
tions of all tensile specimens within the group of slab specimens of a given polymer type.
bSorae samples were inadequately cleaned, so some values are high.
C0ata for fabric-reinforced neoprene FML No. 42 were not included.
Source: Haxo et al, 1982, p 84.
-------
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-------
TABLE 5-40. RETENTION OF MODULUS3 OF POLYMERIC FMLS
ON IMMERSION IN MSW LEACHATE
Polymer
Butyl rubber
Chlorinated polyethylene
Chlorosulfonated
polyethylene
Elasticized polyolefin
Ethyl ene propylene rubber
Neoprene
Polybutylene
Polyester elastomer
Polyethylene
Polyvinyl chloride
Polyvinyl chloride +
pitchd
S-200 of
FML unexposed FML
number^ psi
44
12
38
86
3
6R
85
36
8
18
41
83R
91
9
37
90
98
75
21
11
17
19
40
67
88
89
52
685
1330
1205
810
735
40. QC
1770
1020
655
755
1040
35. 8C
855
1235
1635
1340
3120
2735
1260
2125
1965
1740
1720
1705
2400
2455
1020
Retention of
original value
after exposure, %
8 mo.
86
85
89
98
54
116
77
99
134
111
100
98
91
79
100
93
101
102
106
87
80
89
91
92
79
96
85
19 mo.
90
89
90
106
46
136
108
103
131
109
99
98
92
77
100
101
101
98
102
85
84
94
91
105
88
95
86
31 mo.
98
95
104
133
57
...
130
107
134
117
105
104
98
76
99
115
106
100
106
98
94
112
104
117
101
105
» • •
aAverage of stress at 200% elongation (S-200) measured in machine and
transverse directions.
bR indicates that the FML is fabric-reinforced.
cReported value is in ppi.
^Stress at 100%>elongation value given; original and subsequent exposed
specimens failed at less than 200% elongation.
Source: Haxo et al, 1982, p 86.
5-89
-------
TABLE 5-41. WASTES AND TEST LIQUIDS IN IMMERSION TESTS
Type
Haste liquids3
Acidic waste
Alkaline waste
Industrial waste
Lead waste
Oily waste
Pesticide waste
Test liquids
NaCl solution
De ionized water
Trace organic
Matrecon Electrical
waste conductivity,
Name number pH ymho/cm
"HN03-HF-HOAc"
"HFL"
"Slop Water"
"Spent Caustic"
"Basin F" water
Lead waste blend
"Oil Pond 104"
"Weed Oil"
"Slurry Oil"
"Weed Killer" waste
5% brine
• • •
Saturated TBPb
W-9 1.1
W-10 3.3
W-4 13.1
W-2 11.3
W-16 7.4
W-14
w ™ o • • •
W-7
W-15
W-ll 3.1
W-19
W-18
W-20
155,000
29,000
129,000
155,000
77,000
• • •
• • •
• • *
• • •
3,200
62,000
• * *
• • •
aFor detailed information on the waste liquids see Haxo et al,
1985b. Analyses of the wastes are summarized in Appendix J.
^Saturated solution of tributyl phosphate (TBP) in DI water.
Preweighed and premeasured slabs, measuring ca 8 x 6 in. each, were
immersed in the tanks of the one-sided exposure test cells (see Figure 5-15).
Two slabs were immersed for each type of FML in each of the wastes so that
testing could be performed after a short exposure (67 to 522 days) and a
longer exposure (751 to 1456 days).
At the end of exposure, the immersed slabs were tested for changes in
the following properties:
- Thickness.
5-90
-------
- Dimensions.
- Weight.
- Volatiles.
- Extractables.
- Tensile properties.
- Modulus of elasticity (if FML was a semi crystalline thermoplastic).
- Tear resistance (if FML was unreinforced).
- Puncture resistance.
- Hardness.
Limited results from testing the exposed slabs are presented in Tables 5-42
through 5-44. Table 5-42 shows the number of days that each particular
slab was immersed, Table 5-43, the changes in weight, and Table 5-44, the
retention of stress at 100% elongation. Tensile testing of the unreinforced
FMLs was performed in accordance with ASTM D412/D638 using a special dumbbell
at a jaw separation rate of 20 ipm. This special dumbbell featured smaller
tab ends, a shorter overall length, and a shorter narrowed section in com-
parison with the ASTM D412 Die C/ASTM D638 Type IV dumbbell. The testing of
the semi crystal line FMLs after the second exposure period was performed at a
jaw separation rate of 2 ipm. On most of the fabric-reinforced FMLs testing
was performed in accordance with ASTM D751, Method B, using 1-in. wide strips
and a 2-in. gage length.
The results of some of the immersion tests are discussed below by
polymer type.
5.4.2.2.1 Chlorinated polyethylene (CPE)--Two types of CPE FMLs were
immersed.One (No. 77) was an unreinforced thermoplastic FML, and the second
(No. 100) was a crosslinked CPE. Liner 100 was added to assess the effect of
cross!inking on the interaction of CPE with wastes.
Except for a small loss in weight of the crosslinked CPE specimens
immersed in the alkaline "Slop Water" waste and in brine (5% Nad), all of
the CPE specimens increased in weight. Much of this increase in weight was
through the absorption of water.
A major difference between the thermoplastic and crosslinked CPE FMLs
was apparent in the dimensional changes that took place during immersion.
The crosslinked CPE (No. 100) increased in dimensions approximately equally
in the machine and the transverse directions whereas the thermoplastic CPE
(No.'77) increased more in the transverse direction and in some cases
simultaneously shrank in the machine direction and expanded in the transverse
direction.
5-91
-------
TABLE 5-43. EXPOSURE OF FML SPECIMENS IN IMMERSION TEST TO VARIOUS HAZARDOUS WASTES - NUMBER OF DAYS OF IMMERSION
in
i
Acidic
Polymeric FML
Polymer
Butyl rubber
Chlorinated
polyethylene
Chi orosulfonated
polyethyl ene
Elasticized poly-
olefin
Ethyl ene propylene
rubber
Neoprene
Polyester elastomer
Polyethylene:
High -density
Low-density
Polypropylene
Polyvinyl chloride
Number
44
77
100
6R
55
36
83R
91
90
75
105
108
106
11
59
88
"HFL"
(W-10)
250
761
250
761
99
931
250
761
250
761
250
761
250
761
250
761
250
761
250
761
99
934
99
927
99
927
250
761
250
761
250
761
"HN03-
HF-
HOAc"
(H-9)
193
751
193
751
267
1253
193
751
193
751
193
751
193
751
193
751
193
751
193
751
99
1262
99
1255
99
1255
193
751
193
751
193
751
Alkaline
"Slop
Hater"
(W-4)
193
823
193
823
99
931
193
823
193
823
193
823
193
823
193
823
193
823
193
99
934
99
927
99
927
193
823
193
823
193
823
"Spent
Caustic"
(W-2)
236
780
236
780
99
1258
238
780
236
780
238
780
236
780
236
780
236
780
236
780
99
1267
99
1266
99
1260
238
780
236
780
236
780
Brine
51
NaCl
(W-19)
174
1456
174
1456
49
1345
174
1458
174
1456
174
1456
174
1456
174
1456
174
1456
174
1456
93
1360
93
1360
51
1322
174
1456
174
1456
174
1456
Indus-
trial
"Basin
F"
(W-16)
1196
1196
67
1288
1195
11%
1196
1195
1196
1196
1196
67
1287
67
1287
67
1287
1196
1196
...
Wastes*
"Lead
Haste"0
(W-H)
238
786
238
786
97
1257
236
786
238
786
236
786
238
786
238
786
238
786
238
786
97
1266
97
1259
97
1259
236
786
238
786
238
786
"Slurry
Oil"
(W-15)
257
761
257
761
99
784
257
761
257
761
257
761
257
761
257
761
257
761
257
761
99
793
99
786
99
786
257
761
257
761
257
761
Oily
"Oil Pond
104"
(W-5)
248
752
248
752
97
1252
248
752
248
752
248
752
248
752
248
752
248
752
248
752
97
1260
97
1253
97
1253
248
752
248
752
248
752
"Weed
Oil"
(W-7)
252
809
252
• • •
99
1279
252
809
252
809
252
809
252
809
252
809
252
809
252
809
99
1288
99
1287
99
1287
252
809
252
809
252
809
Organic
trace
Sat'dc
TBP
(H-20)
522
1106
522
1112
522
1112
522
1119
522
1119
522
1090
522
1076
522
1076
522
1106
522
1035
522
1070
522
1055
422
1090
522
1035
522
1055
522d
1070*
Pest-
icide
"Weed
Killer"
(W-ll)
242
807
242
807
97
1259
242
807
242
807
242
807
242
807
242
807
242
807
242
807
97
1268
97
1267
97
1261
242
807
242
807
242
807
Water
De io-
nized
(W-18)
174
1434
174
1434
49
1323
174
1458
174
1434
174
1434
174
1456
174
1434
174
1434
174
1434
93
1360
93
1322
51
1322
174
1434
174
1434
174
1434
aMatrecon waste serial number shown below identification. Analyses
bBlend of three waste streams.
cSaturated solution of tributyl phosphate (TBP) in deionized water.
dFML No. 89.
Source: Haxo et al 19856, p 236.
of the wastes are summarized in Appendix J.
-------
TABLE 5-43. EXPOSURE OF FML SPECIMENS IN IMMERSION TEST TO VARIOUS HAZARDOUS HASTES - PERCENT INCREASE IN WEIGHT
cn
IO
CO
Percent increase In weight of samples
Acidic
Polymeric F«l
Polymer
Butyl rubber
Chlorinated
polyethylene
Chlorosulfonated
polyethylene
Elasticlzed poly-
olefln
Ethyl ene propylene
rubber
Neoprene
Polyester elastomer
Polyethylene:
High-density
Low-density
Polypropylene
Poly vinyl chloride
Number
44
77
100
6R
55
36
83R
91
90
75
105
108
106
11
59
88
"HFL"
(H-10)
2.74
3.71
9.43
12.9
4.2
9.24
6.75
8.9S
5.41
7.74
0.25
1.05
3.06
3.05
16.7
23.9
9.60
12.0
0.55
2.03
0.05
0.16
-3.3
0.08
0.05
-0.02
10.2
18.1
2.76
0.86
7.60
14.3
"HN03-
HF-
HOAc"
(W-9)
1.39
3.77
9.31
19.9
2.0
21.2
10.3
10.0
7.46
10.9
2.68
7.57
2.64
4.20
18.3
50.9
10.8
17.4
4.15
6.41
0.1
0.2
-0.3
0.3
0.1
-0.01
16.8
22.1
-2.82
-6.12
19.8
28.2
Alkaline
•Slop
Hater"
(U-4)
2.04
1.81
1.50
1.89
-0.5
1.83
3.79
7.65
3.84
5.66
17.3
20.7
2.71
3.98
3.13
3.34
0.38
2.66
e
e
0.2
0.52
3.5
1.07
0.1
0.08
-13.5
-11.1
-6.35
-15.7
-13.5
-12.1
"Spent
Caustic"
(H-2)
0.37
0.74
0.64
1.11
0.7
0.2
3.32
4.30
2.17
3.28
0.54
0.56
1.34
1.59
0.23
1.30
0.82
1.53
0.64
1.29
0.2
0.01
0.1
0.1
0.2
0.1
0.09
0.43
-3.00
-0.89
0.04
1.08
Brine
5J
NaCl
(W-19)
0.87
1.4
2.54
1.3
0.85
-1.2
5.75
4.06
5.06
5.6
0.09
0.3
2.19
1.0
1.19
1.0
3.54
...
-0.69
1.5
0.03
0.09
0.07
0.09
-0.11
-0.05
-4.81
-6.2
-4.82
-7.8
-1.51
-1.8
Indus-
trial
"Basin
F"
(H-16)
• • •
1.0
• • •
2.0
0.3
1.2
• • •
e
• • *
5.7
• • »
1.0
• • *
e
* • •
1.0
...
3.2
• • •
1.2
-0.3
0.1
1.1
0.2
0.7
0.5
...
1.0
• • •
0.7
...
...
•Lead
Haste"0
(W-14)
20.1
28.7
70.9
119
23.0
29.3
83.0
121
69.6
116
18.2
17.0
23.0
24.8
29.3
34.7
45.6
59.1
7.57
7.40
5.t)
4.5
3.1
5.3
6.9
5.9
4.36
-1.54
8.81
7.39
2.22
-5.15
on Immersion In different wastes'
"Slurry
Oil"
(W-15)
32.3
31.18
S9.5
d
11.9
115
51.1
105
53.2
111
21.8
29.4
15.8
19.8
35.3
34.2
60.7
142.6
17.1
16.6
4.4
8.0
8.5
12.0
0.4
1.4
10.7
18.5
11.3
28.9
7.2
14.1
Oily
•011 Pond
104"
(H-5)
97.5
104
31.6
36.9
12.4
20.9
75.10
49.5
58.5
55.0
.33.5
28.9
35.4
26.5
80.1
84.7
25.8
26.3
7.90
8.47
3.3
6.6
8.4
10.3
0.6
6.8
-7.65
-10.4
-1.54
-0.54
-10.3
-9.9
"Heed
Oil"
(W-7)
70.8
64.2
117
...
e
118
202
368
211
348
44.2
38.1
73.4
84.4
79.4
76.2
94.8
89.3
16.3
14.7
6.4
7.3
10.7
14.0
1.4
9.1
10.0
14.3
33.4
24.7
18.1
25.2
Organic
trace
Sat'de
TBP
(H-20)
18.1
23.1
117
121
36.2
37.5
31.5
30.1
38.3
31.7
7.9
9.7
6.8
9.8
5.2
5.9
49.4
41.1
4.7
4.6
0.33
O.S
0.44
0.5
0.33
-1.3
57.7
52.8
39.7
40.7
47.6*
47.5*
Pest-
icide
"Heed
Killer"
(U-ll)
0.76
1.57
9.62
12.7
2.8
7.3
13.07
17.26
12.3
1S.7
0.00
0.49
3.71
4.51
8.09
20.4
8.54
11.4
2.39
4.15
0.5
0.2
0.2
0.2
0.07
-O.I
4.03
5.13
0.46
0.95
2.89
1.62
Hater
Del fl-
owed
(U-18)
1.34
4.4
5.66
12.4
1.45
7.5
7.99
15.8
7.73
18.9
-0.04
0.6
2.62
3.3
1.93
3.6
7.10
11.4
0.00
-0.4
0.03
0.6
0.03
0.2
-0.01
0.00
0.21
-1.6
1.18
-0.5
0.65
-0.1
*Matrecon waste serial number shown below Identification. Analyses of wastes are summarized In Appendix J. Immersion tines for the respective
data are presented In Table 5-42.
bBlend of three waste streams.
(Saturated solution of tributyl phosphate (TBP) 1n detonlzed water.
dNot measured because Immersed specimen had become very "gooey* and seemed partially dissolved.
*Not measured.
fFH No. 89.
Source: Haxo et al. 198Sb. p 238.
-------
TABLE 5-44. EXPOSURE OF FH SPECIMENS IN IMMERSION TEST TO VARIOUS HAZARDOUS HASTES - RETENTION OF STRESS AT IQOt ELONGATION
cn
I
Retention of original property on In
Acidic
Polymeric FML
Polymer
Butyl rubber
Chlorinated
polyethylene
Chlorosulfonated
polyethylene
Elastlclzed polyolefin
Ethyl ene propylene
rubber
Neoprene
Polyester elastomer
Polyethylene:
High -density
Low-density
Polypropylene
Poly vinyl chloride
Number
44
77
100
6R
55
36
83R
91
90
75
105
108
106
11
59
88
Original
value6,
PSl
308
900
618
938
880
923
760
338
558
2585
2510
2583J
1320
1210J
3038J
1420
995
1735
"HFL"
(W-10)
84
93
98
117
93
79
98
126
91
110
97
105
92
116
86
100
82
104
98
117
101
89'
97
1011
k
lOll
83
95
99
124
70
83
"HN03-
HF-
HOAc"
(W-9)
70
88
92
129
g
45
81
68
100
71
99
93
107
88
75
58
83
62
80
h
103
79l
99
105'
96*
84
93
199
252
68
70
Alkaline
"Slop
Water"
(W-4)
85
89
113
130
96
110
149
180
119
169
82
93
69
63
88
107
96
115
90
9
h
901
97i
98'
98'
196
206
161
239
183
in
"Spent
Caustic"
(W-2)
81
91
115
126
88
119
150
171
130
164
95
109
90
107
93
100
97
121
94
104
101
95*
100
ggl
106*
103
110
103
123
86
99
Brine
51
NaCl
(W-19)
103
89
124
152
91
121
115
9
104
134
102
114
104
9
85
99
106
144
109
114
104*
104
1031
105*
116
139
136
185
96
125
Indus-
trial
•Basin
F"
(W-16)
...
76
• • •
126
103
85
...
9
• • *
152
119
9
* • •
104
...
93
103
h
83'
100
102'
k
102'
'«
...
106
...
...
•Lead
Waste'c
(M-14)
59
57
37
18
67
44
98
89
79
91
80
76
60
47
83
73
50
38
91
91
100
82'
&
$5'
82
91
89
87
83
95
merslon In different
"Slurry
011"
(M-15)
66
55
44
f
74
49
90
73
95
85
70
72
63
61
65
60
58
40
79
75
99
86'
91i
100'
k
108'
89
118
114
107
99
122
Oily
•Oil Pond
104'
(W-5)
44
45
44
48
62
77
49
88
58
85
62
75
38
57
66
58
46
70
82
95
102
88'
92
90'
100'
168
186
118
145
145
172
wastes9 ,S
"Weed
Oil"
(W-7)
36-47*
38
8
...
24
28
7-46*
f
34
f
55-596
54
28
f
59-646
67
25-26*
27
68-69*
77
98
83'
Si
$7'
48-70*
46
32-35*
45
37-41*
45
Organic
trace
Sat'dd
TBP
(H-20)
79
60
6
9
48
55
9
9
80
106
71
87
9
a
82
89
37
38
90
90
92]
89'
104J
103'
109'
107'
15
18
27
28
23j
25'
Pest-
icide
•Weed
Killer"
-------
As was anticipated, the cross!inked CPE increased less in weight on
immersion in the wastes than did the thermoplastic uncrossl inked FML.
However, the effects of swelling did not necessarily carry over into the
physical properties (Table 5-44). In the case of the samples immersed in the
nonoily wastes, both the crosslinked and the thermoplastic sheetings tended
to increase in modulus (stress at 100% elongation), i.e. to stiffen, with the
exception of the crosslinked CPE immersed in the acidic wastes. The thermo-
plastic CPE tended to stiffen more than the crosslinked CPE. Of the samples
immersed in the oily wastes, even though both FMLs lost in modulus, the
retention of S-100 was significantly less for the thermoplastic CPE than for
the crosslinked. The thermoplastic CPE lost severely on exposure to the
"Slurry Oil" waste, the lead waste, the "Weed Oil" waste, and the trace
organic solution. The "Weed Oil" waste appeared to have completely dissolved
the thermoplastic CPE specimen. The retention of elongation at break was
generally less than 100% and was about equal for the thermoplastic and
crosslinked compounds.
The thermoplastic FML (CPE 77) increased significantly in weight in
the saturated TBP solution. This increase in weight is the net of the water
and TBP that were absorbed minus the plasticizer in the original compound
that might have been lost to the solution. To determine how much of the
original plasticizer migrated into the solution, the extractables obtained
after the the volatiles were removed from the sample were analyzed for total
TBP content. The amount of plasticizer remaining in the exposed FML was
calculated. Table 5-45 presents the results, which indicate that most of the
plasticizer (i.e. the extractables) in the original compound had remained in
the FML.
5.4.2.2.2 Chlorosulfonated polyethylene (CSPE)—Both of the CSPE FMLs
tested in immersion were"potable" grade CSPE compounds. Overall, the two
FMLs responded very similarly to the wastes, even though one was fabric
reinforced and the other was not. All of the immersed specimens swelled and
increased in weight. The samples immersed in the oily wastes increased the
most. These increases ranged from 30% to more than 350%. In the predomi-
nantly aqueous wastes, the weight increases and the amount of water absorbed
as indicated by the volatiles were less significant. Furthermore, the weight
increases of the samples immersed in deionized water were greater than those
immersed in wastes and liquids containing high salt concentrations, e.g. the
"Spent Caustic" waste. The extractables increased only among those specimens
immersed in the oily wastes, indicating absorption of these wastes. The
specimens immersed in aqueous wastes had approximately the same extractables
as the unexposed sheeting. This indicates that the loss of plasticizer to
the waste was low.
The "Weed Oil" waste was by far the most aggressive toward the CSPE FMLs
resulting in significant losses in modulus (Table 5-44). Losses in modulus
were much less in the other oils and not to the extent that might be anti-
cipated from the swelling. These CSPE FMLs appear to have crosslinked during
the Immersion.
5-95
-------
TABLE 5-45. ANALYSES OF CPE AND PVC FMLS
EXPOSED IN SATURATED TBPa SOLUTION
Parameter CPE PVC
Natrecon FML number 77 59
Extractables of unexposed liner, % by
weight of the original liner 9.13 35.9,37.4
Exposure time, days 1112 1055
Extractables after exposure, %
exposed FML (dbc): 26.1 51.7
, % exposed FML (dbc) 19.8 23.3
Extractables, non-TBP, % exposed
FML (dbc)
Calculated extractables remaining in
original compound after exposure^, %
6.3
7.9
28.4
37.0
aTributyl phosphate.
^Analyses of extract by gas chromatography.
cdb = dry basis, i.e. devolatilized basis.
^Non-TBP extractables divided by sum of non-extracted FML and non-TBP
extractables.
Source: Haxo et al, 1985b, p 152.
With respect to the nonoily wastes, exposure resulted in increases in
weight ranging from approximately 2.2 to 20%, major increases in modulus
and in some cases decreases in elongation at break, such as in the "Slop
Water" waste. The changes in modulus and elongation at break reflect the
crosslinking reaction that took place during the immersion.
5.4.2.2.3 Ethylene propylene rubber (EPDM)--One of the EPDMs was a
cross linked FML (EPDM 91), and the second was a fabric-reinforced (8 x 8,
polyester) thermoplastic FML (EPDM 83R). The response of these FMLs to the
wastes and test liquids was generally different though in some, e.g. in
deionized water, the two responded similarly.
Contrary to what would normally be expected, the thermoplastic EPDM
(No. 83R) absorbed less waste and retained its properties better than the
crosslinked EPDM (No. 91). Even in the case of the oily wastes, the ab-
sorption was generally less.
5-96
-------
In the case of the nonoily wastes, the crosslinked EPDM increased
significantly more in weight in the acidic wastes and in the "Weed Killer"
waste. This appears to reflect the sensitivity to moisture on the part of
this FML.
The volatiles contents determined after immersion indicated that, in
most cases, the weight increases were due to water absorption, particularly
in the crosslinked specimens immersed in the acidic wastes. The extractables
data indicated that little if any of the plasticizer in the original com-
pounds was lost to the wastes. The only specimens that increased in ex-
tractables were those that had been immersed in the oily wastes.
The effects of the immersion on stress at 100% elongation generally
reflected the amount of weight increase, particularly for those specimens
immersed in the oily wastes and the crosslinked EPDM immersed in the
"HN03-HF-HOAc" acidic waste.
The effects of the immersion on elongation at ultimate break were
highly variable with retentions varying from 47 to 154%. The elongation
of the thermoplastic, fabric-reinforced sheeting increased in all cases,
whereas most of the crosslinked specimens immersed in the oily wastes lost
in elongation.
5.4.2.2.4 Polyester elastomer (PEL)—An experimental PEL (No. 75) was
tested"!The specimens increased in weight on immersion in all but possibly
two of the wastes. These losses were minor and may have been within ex-
perimental error. The PEL specimens gained weight principally in the hydro-
carbon oily wastes; the gain in weight in the solution containing tributyl
phosphate was not as great. The specimens immersed in the acidic "HN03-
HF-HOAc" waste gained weight significantly; in addition, they lost severely
in elongation as had the same sheeting in the one-sided exposure cells. This
deterioration was the result of the hydrolysis of the polyester polymer. The
retention in stress at 100% elongation of the PEL film tended to decrease
with an increase in weight. Except for the loss in elongation in the acidic
waste, which was drastic, the retention of elongation was good.
5.4.2.2.5 Polyethylene (PE)--Neither the HOPE nor the LDPE sheetings
immersed in this study were marketed as FMLs, and both were nonpigmented.
Both sheetings exhibited comparatively low values for weight increases in
all wastes. However, as with the other polymeric FMLs, the weight increases,
though low, were the greatest in the specimens exposed in the oily hydro-
carbon wastes. The LDPE increased in weight more than the HOPE in these
wastes. The saturated TBP solution caused only a slight increase in weight.
The weight increases in all the other wastes were less than 0.6% except for
the LDPE exposed to the "Slop Water" waste.
Note: As indicated above, the sample of HOPE (No. 105) in-
vestigated in the immersion test was not marketed as an
FML, nor was the grade of HOPE used in that sheeting known
to have been used in the manufacture of FMLs. We later
5-97
-------
found by differential scanning calorimetry that it was
considerably more crystalline than grades of polyethylenes
used in lining materials, had a higher density, and a
considerably higher modulus of elasticity than the
modulus of the HOPE used in FMLs that are now available.
We also found that the HDPE (No. 105) showed indications
of inadequate resistance to environmental stress-cracking
compared with the HDPE currently used in FMLs. In a
stress-cracking test, the HDPE sheeting (No. 105) was
tested in accordance with ASTM D1693 but at a thickness of
30 mils, which is below the required thickness for this
test. It sustained some early breaks (216 h) at 100°C,
whereas currently-available HDPE FMLs tested at thick-
nesses of 80 and 100 mils did not fail in 1,000 hours at
100°C. At the present state of knowledge of HDPE FML
performance, specific correlations between environmental
stress-cracking resistance under different conditions and
field service of FMLs have not been established.
5.4.2.2.6 Polyvinyl chloride (PVC)--Three different PVC FMLs (Numbers
11, 59^ and 88) were immersed, representing PVC FMLs from three different
suppliers.
These three PVC FMLs differed considerably among themselves and in their
responses to the different wastes. The changes in weight during immersion
ranged from significant loss, i.e. 15.7%, to substantial gains, i.e. 57.7%,
depending on the waste liquid and the immersion time. All three sheetings
lost weight in the "Slop Water," the brine, and "Oil Pond 104" waste. In
water they all initially increased in weight and then lost weight. In other
wastes, some gained and others lost weight. All increased in volatiles
content which reflects the absorption of water from the wastes. Analysis of
the extractables after removal of the volatile constituents indicated that in
several cases there was substantial loss in the original plasticizer, such as
was the case with the specimens immersed in the "Slop Water." In some cases,
the extractables content increased due to the absorption of nonvolatile
organics, e.g. hydrocarbon oils. Analysis of the extractables of the sample
of PVC 59 immersed in the saturated TBP solution and which had increased
significantly in weight showed that the original plasticizer had not been
extracted by the immersion.
The effects on the dimensions of the immersed specimen varied greatly
but generally correlated with the weight changes, i.e. if the specimen
increased in weight, the dimensions increased, and if the specimen lost
weight, it decreased in length and width. In the case of shrinkage, a
confined FML would come under tension, possibly causing a hole which could
become larger with increased shrinkage.
The effects on tensile properties appeared to correlate negatively with
the weight changes. Those specimens that lost weight all became stiffer as
is shown by the retention of stress at 100% elongation (Table 5-44); those
that increased in weight generally became softer. The effects of weight loss
5-98
-------
also showed up in the retention of elongation for those FMLs which lost a
substantial amount of plasticizer and which not only became stiff, but lost
in elongation at break.
Overall, the PVC FMLs varied considerably in their response to different
wastes. Certain wastes, such as the highly alkaline wastes, were particular-
ly aggressive toward the PVC; certain oils can cause loss of plasticizer and
excessive stiffening and loss of elongation. Concurrent with these losses, a
PVC FML can shrink and develop tension in the sheets.
5.4.2.3 Immersion in Test Liquids—
Immersion of samples of FMLs in test liquids of known composition can
be used to make a preliminary test of the compatibility of an FML and a
waste liquid that contains the constituents of the test liquid. This type of
immersion test has also been used to determine the solubility parameters
of FMLs and to develop criteria for assessing the chemical compatibility
of FMLs. Nevertheless, in terms of FML-waste compatibility, the results of
such tests are limited because of lack of knowledge about the interaction
between a combination of liquids and an FML.
In the following subsections, data resulting from immersion tests with
liquids of known compositions are presented.
5 ..4.2.3.1 Eqjnl ibri urn swell ing of FMLs and FML-related compositions
in test~Tiquids--As part of a study to determine the solubility parameters
of FMLs, Haxo et al (1988) determined the equilibrium "volume" swelling
of 28 FML-related polymeric compositions in 30 organics and DI water. These
28 polymeric materials included thermoplastic, crosslinked, and semicrystal-
line compositions of which 22 were commercial FMLs or sheetings and six were
laboratory-prepared compositions. This group of 28 compositions included
variations in polymers and compounds, including differences in polymer type,
level of crystallinity, crosslink density, filler level, and amount and type
of plasticizer. The results of determining the solubility parameters are
presented in Section 4.2.2.4.3. The polymer compositions used in the swell-
ing tests are listed in Table 5-46. Detailed data on the composition and
properties of the materials used in ths study are presented in Appendix
F. The 30 organics which were used in the study and which are listed in
Table 5-47, represent a wide range of solubility parameters, as is shown in
Table 5-48.
To determine the equilibrium swelling of each polymeric material in the
test liquids, the weight of an immersed sample was monitored until a maximum
value (i.e. equilibrium) was reached. A sample consisted of three FML
specimens, which were placed in a 20 mL disposable scintillation vial for
each combination. The inside of the vial cap was lined with Teflon-coated
aluminum foil to prevent the loss of organics. The 20 mL vial was satis-
factory for most combinations of polymeric compositions and organics;
however, for those combinations in which excessive swelling took place, the
specimens were transferred to 70 mL vials. In all vials, the specimens were
hung so they did not touch each other.
5-99
-------
TABLE 5-46. POLYMERIC COMPOSITIONS IN SWELLING TESTS TO
DETERMINE EQUILIBRIUM SWELLING
Matrecon
identification Type of
Polymer number3 polymer0
Chlorinated polyethylene
Chlorosulfonated poly-
ethylene
Epichlorohydrin rubber
Ethyl ene propylene rubber
Ethyl ene vinyl acetate
Neoprene
Nitrile rubber
Polyester elastomer
Polybutylene
Polyethylene:
Low-density
Linear low-density
High-density
HDPE/EPOM-alloy
Polyurethane
Polyvinyl chloride
Elasticized polyvinyl
chloride
Polyvinyl chloride,
oil-resistant
195
335R
378R
169R
174R
DOY-3d
DOZ-2d
DPOd
178
232
308A
168
OPNd
316
323
221A
309A
284
184
263
305
181
351
153
DPQC
176R
144
TP/AM
TP/AM
TP/AM
TP/AM
TP/AM
TP/AM
TP/AM
TP/AM
TP/AM
XL/ AM
XL/AM
TP/AM
XL/AM
XL/ AM
TP/CX/AM
TP/CX/AM
CX
CX
CX
CX
CX
CX
CX
TP/AM
TP/AM
TP/AM
TP/AM
TP/AM
Extract-
ables, %
14.85
4.48
7.94
11.29
7.15
-------
TABLE 5-47. ORGANICS USED IN THE EQUILIBRIUM
SWELLING TESTS BY TYPE OR CLASS
Class of organic
Specific organic
Alkanes
Aromatic hydrocarbons
Alcohols
Chlorinated hydrocarbons
Esters
Ketones
Nitrogen compounds
Phenols
n-Octane
Isooctane
Cyclohexane
Xylenes (mixture of o-, m-, and p-)
Tetrahydronaphthalene "Tetralin®"
Methanol
2-Ethyl-l-hexanol
n-Propanol
Cyclohexanol
Benzyl alcohol
Furfuryl alcohol
Ethylene glycol
Tetrachloroethylene
Trichloroethylene
Di(ethylhexyl) phthalate
Diethyl phthalate
Isoamyl acetate
Ethyl acetate
Diethyl carbonate
Butyrolactone
Propylene carbonate
Acetone
Methyl ethyl ketone
Cyclohexanone
Methyl isobutyl ketone
Nitroethane
N,N-Dimethylacetamide
Quincline
2-Pyrrolidone
m-Cresol
Source: Haxo et al, 1988, p 24.
5-101
-------
TABLE 5-48. PROPERTIES OF THE OR6ANICS USED IN FML EQUILIBRIUM SWELLING AND SOLUBILITY PARAMETER STUDY
Property
Sa. call/2 cm-3/2
Name
n-Octane
Isoamyl acetate
2-Ethyl-l-hexanol
Methyl isobutyl ketone
Ethyl acetate
n-Propanol
Nitroethane
Methyl ethyl ketone
Methanol
Cyclohexane
Di ethyl carbonate
Cyclohexanol
Di (ethyl hexyl)
phthalate
Cyclohexanone
Furfuryl alcohol
Di ethyl phthalate
N,N-Dimethylacetamide
Ethyl ene glycol
Tetralin
Trichloroethylene
m-Cresol
Tetrachl oroethyl ene
Qulnoline
Benzyl alcohol
Propylene carbonate
Butyrolactone
2-Pyrrol1done
Water
Isooctane
Xylenes (o, m, and p)
Acetone
0
7.6
8.4
9.9
8.3
8.9
12.0
11.1
9.3
14.5
8.2
8.8
10.9
8.9
9.6
11.9
10.0
11.1
16.1
9.8
9.3
11.1
9.9
10.8
11.6
13.3
12.9
13.9
23.4
7.0
8.8
9.8
d
7.6
7.5
7.8
7.5
7.7
7.8
7.8
7.8
7.4
8.2
8.1
8.5
8.1
8.7
8.5
8.6
8.2
8.3
9.6
8.8
8.8
9.3
9.5
9.0
9.8
9.3
9.5
7.6
7.0
8.7
7.6
P
0
1.5
1.6
3.0
2.6
3.3
7.6
4.4
6.0
0.0
1.5
2.0
3.4
3.1
3.7
4.7
5.6
5.4
1.0
1.5
2.5
3.2
3.4
3.1
8.8
8.1
8.5
7.8
0
0.5
5.1
h
0
3.4
5.8
2.0
3.5
8.5
2.2
2.5
10.9
0.1
3.0
6.6
1.5
2.5
7.4
2.2
5.0
12.7
1.4
2.6
6.3
1.4
3.7
6.7
2.0
3.6
5.5
20.7
0
1.5
3.4
Organic,
no., and codeb
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Rd
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
1
1
2
1
P
1
1
1
2
2
2
3
3
3
1
1
1
2
2
2
3
3
3
1
1
1
2
2
2
3
3
3
3
1
1
3
Rh
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
3
1
1
2
MPC,
ec
-57
-78
-76
-80
-84
-127
-90
-87
-98
6.5
-43
22
-50
-47
-29
-3
-20
-13
-35
-87
10
-22
-15
-15
-55
-45
25
0
-107
-48-+13
-95
BPC,
°C
125
142
183
114
77
97
112
80
65
81
126
160
384
155
170
298
165
196
207
87
203
121
237
205
240
204
245
100
99
138-144
56
Density0,
g/cm3
0.703
0.876
0.833
0.801
0.902
0.804
1.045
0.805
0.791
0.779
0.975
0.963
0.981
0.947
1.135
1.118
0.937
1.113
0.973
1.462
1.034
1.623
1.095
1.045
1.189
1.12
1.12
1.00
0.692
0.868
0.791
Solubility in
waterd at 25°C,
mg/L
0.66
20,000
700 (20°C)
17,000
80,800
Miscible
46 ,800
240,000
Miscible
55
Insoluble
37,500 (26.5°C)
0.4*
23,000
Miscible
0.09e
Miscible
Miscible
Insoluble
1,100
25,100 (40°C)
2,870 (20°C)
6,090 (20CC)
800 (20°C)
Moderate
Miscible
Miscible
* • •
2.4
190
Miscible
aBarton (1975). «0 = Hildebrand solubility parameter; fy * dispersive solubility parameter;
6p = polarity solubility parameter; and ^ = hydrogen-Bonding solubility parameter.
''Each code was made up of three digits representing the range values assigned to an organic after the
ordering of organics by each component solubility parameter as presented in Section 5. Rj is the range
value for the dispersive solubility parameter; Rp the range value for the polarity solubility parameter;
and Rh the range value for the hydrogen-bonding solubility parameter. Each selected test organic was
assigned a unique number.
cLange (1967); MP is the melting point and BP is the boiling point of the organic.
dRiddick and Bunger (1970).
(1982).
5-102
-------
The specimens, which measured 0.5 x 1.5 in., were cut from slabs or
sheetings with a die used for cutting out ESC specimens (ASTM D1693).
However, the specimens were treated as a unit, not individually, and were
weighed as a set before and after immersion. Before immersion, the weight
of the sets of specimens ranged from 0.5 to 5 g with most weighing under
2 grams.
The specimens were weighed before immersion and after 2 days, 1 week,
and 2 weeks. Additional weighings were taken approximately once a week if
the specimens had not reached equilibrium after the second week of exposure.
Once equilibrium swelling had been reached, the equilibrium swelling based
on volume was calculated from the equilibrium swelling based on change in
weight. The volume increase was calculated by correcting for the density of
the respective organics used to swell the FML specimens. No adjustment was
made for the initial density of the specimen; neither was any adjustment made
for loss of plasticizer or any other material that may have been extracted
from the original specimens. Adjustment for loss of extracted components
would have required extraction tests of specimens after they had been dried
out.
Results of determining the equilibrium "volume" swelling of the poly-
meric specimens are presented in the following tables:
- Table 5-49.
- Table 5-50.
- Table 5-51.
Equilibrium Volume Swelling of the CPE and CSPE Specimens
Immersed in 30 Organics and in Water.
Equilibrium Volume Swelling of
Nitrile Rubber (NBR), PEL, and
30 Organics and in Water.
the ECO, EPDM, EVA, CR,
PB Specimens Immersed in
Equilibrium Volume Swelling of the LDPE, LLDPE, HOPE,
HOPE-A, PU, PVC, PVC-E, and PVC-OR Specimens Immersed in
30 Organics and in Water.
Crystallinity of the base polymer appears to be the dominant factor in
reducing the swelling of an FML or an FML-related composition in all of the
organics and to override both the solubility parameters and crosslinking.
Among compositions based on amorphous polymers, the proximity of the com-
ponent solubility parameters to those of the organics could be used in most
cases to indicate the swelling and the probability of changes in properties.
Nevertheless, empirically derived data are still necessary for untested
combinations of organics and FMLs.
5.4.2.3.2 Immersion testing of FMLs to develop chemical compatibility
requirements--As there were no established or accepted benchmarks for FML
performance based on immersion tests, Bellen et al (1987) conducted a test
program to generate data on the chemical resistance of commerical FMLs.
It was anticipated that the data would be useful in assessing the results of
compatibility tests, such as those performed in accordance with EPA Method
5-103
-------
TABLE 5-49. EQUILIBRIUM VOLUME SWELLING OF THE CPE AND CSPE SPECIMENS' IMMERSED IN 30 ORGANICS AND IN WATER
cn
I
Liquid
Isooctane (Ref. Fuel A)
n-Octane
Cyclohexane
Methyl isobutyl ketone
Isoamyl acetate
o-Xylene
Di ethyl carbonate
Dioctyl phthalate
Ethyl acetate
Methyl ethyl ketone
Trichloroethylene
Cyclohexanone
Acetone
Tetralin
Tetrach 1 oroethyl ene
2-ethyl-l-hexanol
Diethyl phthalate
Quinoline
Cyclohexanol
N,N-dimethylacet amide
m-Cresol
Nitroethane
Benzyl alcohol
Furfuryl alcohol
1-Propanol
Butyrolactone
Propylene-l,2-carbonate
2-Pyrrolidone
Methanol
Ethylene glycol
Water
Hildebrand
solubility
parameter
7.
7.
8.
8.
8.
8.
8.
8.
8.
9.
9.
9.
9.
9.
9.
9.
10.
10.
10.
11.
11.
11.
11.
11.
12.
12.
13.
13.
14.
16.
23.
0
6
2
3
4
8
8
9
9
3
3
6
8
8
9
9
0
8
9
1
1
1
6
9
0
9
3
9
5
1
4
CPE
195
14.85b
4.24
6.08
26.6
Qe
De
41.2
87.1
361.9
06
De
De
De
102.9
06
122.6
4.57
191.4
De
2.13
De
67.9
58.8
35.2
17.6
2.13
93.8
23.0
111.6
3.56
2.21
3.99
CPE
335R
4.48
10.1
12.5
51.0
188.5
200.0
ne
72.5
218.1
137.5
137.9
Oe
251.3
56.3
De
De
3.96
125.2
De
2.96
17.3
48.5
38.2
27.4
6.00
5.42
46.9
9.08
38.8
9.27
3.64
6.14
FML-
CPE
378R
7.94
5.83
6.40
16.8
06
De
53.0
27.0
141.7
107.4
282.0
62.7
121.4
85.0
De
45.2
8.58
72.7
06
7.91
62.0
23.1
38.5
9.56
1.66
9.12
90.2
13.6
107.1
3.91
5.33
8.91
-polymer/
CSPE
169R
11.29
1.50
1.77
119.5
38.4
42.1
577.2
8.61
32.0
10.7
20.4
435.0
139.4
7.56
353.5
468.3
1.52
9.57
96.8
2.40
17.8
14.8
3.97
6.87
3.82
2.03
4.38
1.37
12.2
7.61
2.06
6.50
'ID numbei
CSPE
174R
7.15C
8.71
12.9
99.7
40.8
45.4
153.2
13.2
29.2
16.5
26.8
oe
101.5
13.3
180.9
160.8
3.12
14.0
79.8
5.65
20.9
19.6
7.64
8.79
5.39
3.13
7.31
5.63
11.2
4.58
3.22
4.44
r/extract<
CSPE
DOY-3
<1.0d
22.8
31.7
137.4
95.5
105.5
291.5
30.2
73.7
36.5
58.4
325.6
190.1
24.5
279.5
263.1
3.30
21.4
159.1
9.24
51.5
42.8
15.3
37.3
20.9
13.9
11.9
1.24
24.8
49.9
2.32
15.4
ibles, %
CSPE
DOZ-2
<1.0d
11.5
14.5
De
63.8
89.3
06
20.0
52.4
24.8
36.3
De
205.9
17.1
Oe
°e
1.46
15.8
202.7
1.78
30.1
30.6
11.9
11.4
4.37
2.25
8.85
1.25
8.92
8.90
0.57
3.00
CSPE
DPO
<1.0d
17.8
24.3
192.6
93.1
102.9
448.2
26.7
65.1
32.3
53.0
508.9
240.8
21.7
523.1
446.1
2.35
18.5
161.6
3.01
33.2
22.9
11.7
8.22
2.98
2.01
7.66
1.94
6.38
9.54
1.47
6.02
CSPE
OPP
<1.0d
21.1
28.2
273.4
118.6
135.8
751.2
33.1
100.4
39.6
67.6
820.8
359.0
28.2
765.7
718.4
3.45
24.2
234.7
4.46
38.6
27.3
14.4
9.95
3.74
3.30
10.2
2.72
12.6
15.4
3.53
5.33
aCPE 195, CPE 335R, CPE 378R, CSPE 169R, and CSPE 174 are commercially manufactured FMLs; further data for these
materials are presented in Appendix F, Table F-7. CSPE compounds labeled DOY-3, DOZ-2, DPO, and DPP are laboratory
prepared compounds; information on these compounds is presented in Appendix F, Tables F-ll and F-12.
bExtractables determined in accordance with Matrecon Test Method 2 (see Appendix E) using n-heptane as the solvent.
cExtractables determined in accordance with Matrecon Test Method 2 (see Appendix E) using acetone as the solvent.
^Calculated from compound formulation.
eD = dissolved or disintegrated.
Source: Haxo et al, 1988, p 125.
-------
TABLE 5-50.
EQUILIBRIUM VOLUME SWELLING OF THE ECO, EPDH, EVA, CR, NITRILE RUBBER (NBR),
PEL, AND PB SPECIMENS3 IMMERSED IN 30 ORGANICS AND IN WATER
O
in
Liquid
Isooctane (Ref. Fuel A)
n-Octane
Cyclohexane
Methyl isobutyl ketone
Isoamyl acetate
o-Xylene
Di ethyl carbonate
Dioctyl phthalate
Ethyl acetate
Methyl ethyl ketone
Trichloroethylene
Cyclohexanone
Acetone
Tetralin
Tetrachl oroethyl ene
2-ethyl-l-hexanol
Di ethyl phthalate
Qu incline
Cyclohexanol
H,N-dimethyl acetamide
m-Cresol
Nitroethane
Benzyl alcohol
Furfuryl alcohol
1-Propanol
Butyrolactone
Propylene-l,2-carbonate
2-Pyrrolidone
Methanol
Ethyl ene glycol
Water
Hildebrand
solubility
parameter
7.0
7.6
8.2
8.3
8.4
8.8
8.8
8.9
8.9
9.3
9.3
9.6
9.8
9.8
9.9
9.9
10.0
10.8
10.9
11.1
11.1
11.1
11.6
11.9
12.0
12.9
13.3
13.9
14.5
16.1
23.4
FML-polymer/ID number/extractables, %
ECO
178
7.63
0.53
0.98
6.35
67.4
71.3
64.3
66.6
25.1
87.6
88.7
102.6
121.4
75.0
154.2
22.4
5.01
97.5
127.0
7.32
127.0
183.8
99.5
123.4
120.5
4.97
108.9
80.3
100.0
13.7
9.30
23.6
EPDM
232
22.78
68.6
86.8
125.9
5.20
5.70
103.1
5.08
4.16
4.96
8.33
135.4
3.00
0.88
68.6
146.0
4.83
0.50
4.92
7.46
3.93
2.72
0.70
0.38
0.24
6.40
0.00
0,80
1.29
1.59
0.49
1.18
EVA
308A
0.75
28.3
34.1
97.4
3.67
27.6
125.6
15.5
12.6
17.8
18.8
249.0
28.4
14.5
82.2
181.8
15.2
6.28
26.2
9.19
7.32
55.5
9.33
11.4
4.54
7.41
2.69
1.06
1.97
5.89
1.55
0.66
CR
168
11.23°
0.96
0.61
30.8
56.1
66.0
109.0
25.9
73.4
33.7
39.4
123.1
111.9
10.1
180.9
105.4
5.27
33.9
97.7
2.32
60.3
27.2
3.08
13.2
1.99
3.84
3.11
0.11
14.9
12.7
1.76
6.55
NBR
DPN
9.84
10.9
30.7
425.7
246.6
256.9
199.0
191.6
317.1
496.8
516.4
701.2
354.0
546.8
90.0
36.1
475.8
672.1
35.0
611.5
D6
439.2
473.7
251.4
26.9
362.5
131.2
151.8
19.5
9.48
9.15
PEL
316
7.25
8.27
19.0
38.3
41.3
105.5
40.3
18.0
44.3
52.3
D6
123.5
33.5
280.3
70.9
16.7
38.0
274.0
16.7
60.7
De
56.1
194.3
174.6
14.8
22.5
8.30
14.6
14.7
2.42
2.62
PEL
323
iO.6
0.86
2.88
4.46
10.5
10.5
17.1
11.0
0.72
11.6
12.9
25.1
15.8
11.2
24.7
14.5
1.51
3.22
21.6
2.40
16.5
De
13.7
17.1
15.3
7.28
9.73
3.30
4.67
4.72
1.67
2.13
PB
22 1A
3.68
25.0
26.3
61.6
9.63
12.9
28.9
6.44
2.50
7.30
6.53
42.5
9.56
21.7
3.26
17.5
1.46
0.80
5.22
2.07
1.97
1.60
2.47
0.85
0.23
1.15
0.52
0.95
0.61
0.98
0.69
1.53
aNitrile rubber (NBR) compound labeled "DPN" is a laboratory-prepared compound; information on this compound is
presented in Appendix F, Tables F-ll and F-12. All of the other materials are commercially manufactured FMLs;
further data for these materials are presented in Appendix F, Tables F-7 and F-8.
bExtractables determined in accordance with Matrecon Test Method 2 (see Appendix E) using n-heptane as the solvent.
cExtractables determined in accordance with Matrecon Test Method 2 (see Appendix E) using acetone as the solvent.
^Calculated from compound formulation.
eD = dissolved or disintegrated.
Source: Haxo et al, 1988, p 126.
-------
TABLE 5-51. EQUILIBRIUM VOLUME SWELLING OF THE LDPE, LLDPE, HOPE, HDPE-A, PU, PVC,
PVC-E, AND PVC-OR SPECIMENS* IMMERSED IN 30 ORGANICS AND IN WATER
Liquid
Isooctane (Ref. Fuel A)
n-Octane
Cyclohexane
Methyl isobutyl ketone
Isoamyl acetate
o-Xylene
Diethyl carbonate
Dioctyl phthalate
Ethyl acetate
Methyl ethyl ketone
Trichloroethylene
Cyclohexanone
Acetone
Tetran
Tetrachloroethylene
2-ethyl-l-hexanol
Diethyl phthalate
Quinoline
Cyclohexanol
N,N-dimethylacetamide
m-Cresol
Nitroethane
Benzyl alcohol
Furfuryl alcohol
1-Propanol
Butyrolactone
Propylene-l,2-carbonate
2-Pyrrolidone
Methanol
Ethylene glycol
Water
Hildebrand
solubility
parameter
(o)
7.0
7.6
8.2
8.3
8.4
8.8
8.8
8.9
8.9
9.3
9.3
9.6
9.8
9.8
9.9
9.9
10.0
10.8
10.9
11.1
11.1
11.1
11.6
11.9
12.0
12.9
13.3
13.9
14.5
16.1
23.4
LDPE
309A
185a
10.1
13.1
23.1
3.67
6.52
19.9
4.56
2.71
3.01
2.72
19.9
5.04
3.23
11.5
25.0
4.21
0.81
3.67
2.07
2.44
2.17
1.12
0.76
0.20
1.01
0.26
0.52
0.79
3.46
0.56
4.61
LLDPE
284
0.65b
11.4
14.2
24.5
4.49
6.18
20.4
2.61
0.92
3.04
4.06
21.5
4.36
1.98
12.3
25.5
1.59
1.36
4.06
1.71
3.93
1.59
0.94
0.44
0.16
1.05
0.66
0.75
0.79
1.74
0.41
1.54
HOPE
184
0.73b
7.06
8.49
11.8
3.62
4.24
12.6
2.37
0.46
2.63
2.53
10.5
3.03
2.42
7.67
13.7
0.52
0.89
3.30
0.86
1.67
2.72
1.17
0.94
0.22
0.77
0.37
0.28
0.86
1.40
0.41
0.62
FML
HOPE
263
i0.6b
4.36
7.68
11.2
2.27
2.75
11.6
2.15
0.64
2.61
2.17
10.9
1.40
1.23
6.80
13.7
0.32
0.45
1.79
0.40
0.52
0.79
0.60
0.17
0.70
0.68
0.16
0.24
0.16
1.09
0.24
0.23
-polymer/ID number/extractables. %
HOPE
305
0.98b
7.89
9.68
12.8
4.23
6.34
14.3
2.69
0.49
2.61
2.55
11.8
4.88
1.64
1.88
13.5
1.06
1.37
4.22
1.21
2.47
2.39
0.90
0.91
0.39
1.15
0.71
0.24
0.90
2.60
0.39
1.51
HDPE-A
181
2.09b
15.9
18.6
34.7
4.36
7.72
28.8
2.96
3.12
3.27
3.42
32.1
5.40
1.41
16.9
41.4
1.44
1.35
5.33
1.81
2.02
1.18
1.89
0.61
0.06
1.34
0.19
0.9
0.54
2.86
0.43
1.60
PU
351
1.50C
4.76
6.79
19.8
95.8
63.4
71.7
56.5
24.3
85.1
214.9
129.3
Df
92.9
233.3
53.4
42.3
80.3
Df
51.8
Df
Df
50.4
Df
735.8
41.0
180.4
13.0
Df
34.4
6.95
1.66
PVC
153
34.57d
21.7
19.9
19.9
Df
245.4
7.92
11.8
176.4
147.5
Df
17.0
of
171.9
111.0
2.64
12.8
86.58
Df
11.2
Df
7.65
44.3
11.8
13.1
19.0
Df
11.9
277.7
17.7
3.43
1.58
PVC
DPQ
40.12d
22.1
20.3
16.4
Df
Df
17.3
23.8
143.7
Df
Df
27.6
Df
Df
Of
0.19
3.02
124.3
Df
0.37
Df
0.68
81.8
9.53
11.3
19.4
Df
27.8
Df
11.7
4.89
4.17
PVC-E
176R
9.13e
3.25
2.70
14.2
Df
Df
84.0
42.6
55.6
Df
of
109.4
Df
Df
Df
64.1
8.34
56.3
Df
9.61
Df
93.1
Df
52.2
23.1
5.04
53.4
16.1
42.9
2.98
3.12
2.32
PVC-OR
144
30.97d
1.83
1.79
4.94
Df
230.6
11.1
10.2
193.7
150.8
Df
22.5
Df
177.0
124.4
16.5
6.08
93.9
Df
2.11
Df
7.32
40.3
1.68
6.22
5.44
178.6
15.5
258.0
17.6
4.32
2.65
aThe PVC compound labeled "DPQ" is a laboratory-prepared compound; information on the this compound is presented in
Appendix F, Tables F-ll and F-12. All of the other materials are commercially manufactured FMLs. Further data for these
materials are presented in Appendix F, Tables F-9 and F-10.
bExtractables determined in accordance with Matrecon Test Method 2 (see Appendix E) using methyl ethyl ketone as the solvent.
cExtractables determined in accordance with Matrecon Test Method 2 (see Appendix E) using n-heptane as the solvent.
dExtractables determined in accordance with Matrecon Test Method 2 (see Appendix E) using 2:1 mixture of CC14 and CH30H
as the solvent.
eExtractables determined in accordance with Matrecon Test Method 2 (see Appendix E) using CH30H as the solvent.
fD = dissolved or disintegrated.
Source: Haxo et al, 1988, p 127.
-------
9090, and could be used to develop general criteria to assess the chemical
compatibility of a specific FML proposed for use in lining specific waste
storage and disposal facilities.
In this program, 6 commerical FMLs were immersed in 20 different
chemical solutions or liquids, including acids and bases, polar and nonpolar
organics, organic and inorganic solutions, and concentration variations. The
FMLs were immersed at 23° and 50°C in the solutions for 1, 7, 14, 28, and
56 days (a short-term test) and for four-month increments up to 2 years (a
long-term test). The immersed samples were observed for changes in appear-
ance, weight, dimensions, and tensile and tear properties. The six FMLs that
were selected for the test program are listed in Table 5-52. They represent
a range of different polymer types, including variations in chemical composi-
tion, polarity, crystallinity, and crosslink density. All six of the FMLs
were unreinforced; five were 30 mils in nominal thickness and the sixth, an
ECO FML, was 60 mils in thickness.
TABLE 5-52. UNREINFORCED FMLS SELECTED FOR CHEMICAL
RESISTANCE TESTING
Polymer
CPE
CSPE-LWb
Epichlorhydrin (ECO)
EPDM
HDPE
PVC
Type of
compound3
TP
TP
XL
XL
CX
TP
Nominal
thickness, mils
30
30
60
30
30
30
Polarity
Polar
Polar
Polar
Nonpolar
Nonpolar
Polar
aTP = thermoplastic; XL = crosslinked; CX = semicrystalline.
DLow water absorption CSPE, i.e. industrial grade.
Source: Bellen et al, 1987, p 29.
The 20 chemical liquids used in the study are listed in Table 5-53.
Four of the chemicals, all organics, were each used at three concentrations
and the NaCl was used at two concentrations to give information on the effect
of concentration.
The FML samples were immersed in chemical solutions in glass jars.
Glass was chosen because of its resistance to the wide range of chemicals
being tested, its transparency (so that the condition of the samples could be
inspected), and the relatively low cost of the jars. For the long-term
immersions, in which the samples were observed for changes in weight and
dimensions at four-month intervals, 1-qt canning jars were used. A screw-on
cap lined with PE was used to control evaporative loss from the jars. Three
1 x 3-ini preweighed and premeasured FML specimens were placed in the canning
jars. For the shorter immersions (up to 56 days), 2-gal apothecary jars were
used. Three slabs were immersed in each jar: two were approximately 8 x 8.5
5-107
-------
in. in size, and the third measured 1x3 inches. The larger slabs were for
the property tests, and the third was used to determine weight and dimension-
al changes. For the shorter immersions, one jar per FML immersion period
solution combination was used. The apothecary jars were sealed with rope
caulking between the glass lid and the jar. Jars containing solutions of
volatile chemicals were also taped with a stretchable heat and moisture-re-
sistant transparent tape to reduce evaporative loss. The sealing methods
were reasonably effective in controlling the loss of volatiles, i.e. MEK and
DCE, as the concentration changes of the organic solutions during the tests
were relatively small.
TABLE 5-53. CHEMICAL LIQUIDS SELECTED FOR FML IMMERSION TESTS3
Name
Formula
Chemical
type
Concentrations,
% wt:wtb
Water
Hydrochloric acid
Sodium hydroxide
Sodium chloride
Potassium dichromate
Phenol
Furfural
Methyl ethyl ketone^
1,2-Dichloroethane
ASTM #2 oil
H20
HC1
NaOH
NaCl
C6H5OH
CH3COC2H5
C1(CH2)2C1
Control
Acid
Base
Salt
Oxidizer
Phenol
Aldehyde
Ketone
Chlorinated-
hydrocarbon
Oil
100
10
10
10, sat'd (ca 35)
10
1,4, sat'd (ca 8)
1,4, sat'd (ca 8)
3,13, sat'd (ca 26)
0.1,0.5, sat'd
(ca 0.8)
1006, sat'd (water
with oil stirred
in)
aAl1 chemicals were technical grade quality or better, per ASTM D543.
t>Part per 100 parts of water.
cBoth the water for water immersion tests and the water used for the
organic chemical solutions were lightly buffered in order to provide pH
control and ionic strength. Sodium bicarbonate and calcium chloride
were used to a level of 100 mg L"l hardness as CaC03 and to provide a
pH of 8.3+0.5.
^An 8% solution of methyl ethyl ketone was used in place of the satu-
rated solution for testing the CPE.
eNeat ASTM #2 oil.
Source: Bellen et al, 1987, p 41.
5-108
-------
All immersions were conducted with an FML surface-to-volume ratio
of approximately 40 ml in.~2 of FML surface area. The surface to volume
ratio was specified for consistency and to assure that the amount of solvent
present in solution would not be limiting. Chemical solutions were mixed in
the immersion jars. Those solutions containing the volatile chemicals were
prepared on the same day that the FML samples were placed in immersion; those
solutions containing the nonvolatile chemicals were prepared on the same day
or the day before the FML samples were immersed.
Immersion jars were placed in controlled temperature chambers. Jars
were set on open wire shelving to allow air circulation for temperature
control. The temperature of jars of water in the chambers placed on top and
bottom shelves were measured twice daily (±2°C tolerance each).
The tests used to measure the physical properties of the different
FMLs and the number of specimens in each test are listed in Table 5-54.
Physical properties of the exposed FML samples were measured after each
exposure period of the short-term test and at the conclusion of the long-term
immersion test. Weight and dimensions were measured after each time period
in the short-term test and after every four months in the long-term test.
Complete results are presented in the final report of Bellen et al
(1987), in which data and discussions are organized by particular FML. No
effort was made to compare material responses because each type of FML has
unique properties and unique responses to immersion.
The authors observed five basic types of response to chemical immersion:
- Changes in physical properties and weight.
- Swelling by changes in dimensions.
- Swelling and softening with loss of strength.
- Shrinking and stiffening with loss of elongation.
- Combination of swelling and shrinking depending on immersion condi-
tions.
The response of FMLs to increased immersion temperature indicated
that higher temperatures (at least up to 50°C) can be used to accelerate the
material response for some FMLs, but not others. With caution, the effects
of temperature could be distinguished from a chemical response.
When the response was minor or the response time very fast, the dif-
ference in results between the 23°C exposure and the 50°C exposure was often
small. In these cases, the higher exposure temperature did not significantly
accelerate the response, but neither did it change the response. This in-
dicates that the higher temperature neither affected the FML nor accelerated
5-109
-------
TABLE 5-54. TESTING OF SAMPLES IN IMMERSION TESTS
Type of FML compound
Test
Crosslinked
Thermoplastic
Semi crystal line
in
i
o
Measurements on
immersion specimens
Thickness
Length and width
Weight
Physical properties
Tensile properties:
Method
Type of specimen
Number of test specimens
Values reported
Dead weight gage3
Calipers3
Analytical balance3
ASTM D412
Die C
5 each direction
Breaking factor (ppi)
Elongation at break (in.)
Dead weight gage3
Calipers3
Analytical balance3
ASTM D882
1 x 4-in. strips
5 each direction
Breaking factor (ppi)
Elongation at break (in.)
Stress at 100% elongation (ppi)
Dead weight gage3
Calipers3
Analytical balance3
ASTM D638
Type IV
5 each direction
Breaking factor (ppi)
Yield strength (ppi)
Elongation at break (in.)
Elongation at yield (in.)
Modulus of elasticity (psi)
Tear resistance:
Method
Type of specimen
Number of specimens
ASTM D624
Die C
5 each direction
ASTM D624
Die C
5 each direction
ASTM D1004
...b
5 each direction
aBel1en et al, 1987, pp 205-13. Three specimens tested for long-term tests; one tested for short-term tests.
bASTM D1004 test specimen is the same as the ASTM 0624 Die C.
Source: Bellen et al, 1987, p 58.
-------
the exposure. Some data indicated that the magnitude of the response did not
increase with temperature, but the rate at which the response stabilized did
increase. For such FMLs, elevating the temperature would effectively ac-
celerate immersion testing. For other FML-chemical combinations, the magni-
tude of response was affected by temperature. The authors concluded that
using elevated temperatures for predicting chemical resistance is generally
not a good practice unless an FML's response to heat stress is known.
All of the FMLs were immersed in three different concentrations of four
organics. Differences in concentration affected the FML responses. As an
example, the effect of furfural concentration on PVC weight change, breaking
strength, and stress at 100% elongation (S-100) modulus is presented in
Figure 5-31. This example shows the importance of knowing concentration
levels in evaluating compatibility or possibly for predicting acceptable
chemical concentrations in waste streams based on allowable levels of proper-
ty change when properties level off at constant values.
100
50
20
2 10
o>
D.
• Weight Change. %
o Breaking Factor, % retention
A S-100 Modulus, % retention
j_
I
I
I
I
Figure 5-31.
i 1234 56789
Concentration, wt/wt percent
Relationship of changes in physical properties to furfural
concentration at 23°C for PVC. (Source: Bellen et al, 1987,
P 96).
Bell en et al (1987) proposed a mathematical curve fitting method for
evaluating immersion data as a function of time. The method assumes the
liner approaches a limit of physical property change asymptotically. The
method can be used to predict the ultimate end point of physical property
change and sampling time intervals for continued immersion testing in the
specific chemical solution or liquid.
5-111
-------
Some of the general conclusions of this study of FMLs in simple chemical
solutions or liquids are:
- Immersing an FML in the waste it is intended to contain and determin-
ing changes in physical and analytical properties is essential for
determining chemical compatibility of the FML with the specific
waste.
- In general, the magnitude of an FML's response to an aqueous solution
containing an organic solvent is a function of its concentration.
However, solutions containing low concentrations of some chemicals can
have a more significant effect on those solutions containing higher
concentrations of other chemicals. These results indicate that
immersing an FML in the major constituents of a given waste is not
satisfactory for determining chemical compatibility between that waste
and the given FML.
- In evaluating the chemical compatibility between an FML and a given
waste, the ability of the FML to come to an equilibrium in the chemi-
cal environment as well as the magnitude of changes in properties
needs to be considered.
- For some FML/waste combinations, increasing the immersion temperature
can be used to accelerate testing. However, for others, increasing
the temperature to 50°C produced a different rather than an ac-
celerated response. Since not all FMLs are suitable for service at
50°C, immersing some FMLs at elevated temperatures may be too aggres-
sive to simulate anticipated use. In addition, the ability of an FML
to resist degradation needs to be considered when evaluating chemical
resistance.
- A change in weight during immersion generally indicates changes in the
properties of an FML.
- Water alone can significantly affect the properties of an FML, parti-
cularly in conjunction with an elevated temperature. The effect of
immersion in water alone should be determined in evaluating the
chemical resistance of an FML.
- Chemical compatibility tables (e.g. those developed by resin and FML
manufacturers) should only be used to screen FMLs to find possible
incompatible combinations. The limitations of compatibility tables
are that materials are usually tested with simple solutions or neat
solvents and only rated qualitatively (e.g. good, fair, or poor)
and that the test conditions used to determine resistance are not
always described. Exposure testing with the specific waste to be
contained is necessary before compatibility can be determined.
- Generalization of any compatibility criteria and the results of
testing an FML after immersion must be done with caution. Even though
5-112
-------
FMLs of similar composition can be expected to respond similarly, the
degree of the response (i.e the amount of property change) may change
with different formulation and manufacturing techniques.
5.4.2.3.3 Immersion testing of seams—As part of a research program to
evaluate FML seams exposed to simulated service conditions, Morrison and
Parkhill (1987) investigated the effects of immersion in a range of test
solutions on samples of FML factory and field seams prepared by the method
appropriate to the specific FML. A total of 37 combinations of FMLs and
seaming methods were immersed in nine solutions, including six chemical
solutions, two brines, and tap water. The FMLs included:
- 30-mil CPE (unreinforced), 4 seam samples.
- 36-mil CPE (fabric-reinforced), 4 seam samples.
- 30-mil CSPE (fabric-reinforced), 2 seam samples.
- 36-mil CSPE (fabric-reinforced), 11 seam samples.
- 38-mil ethylene interpolymer alloy (EIA) (fabric-reinforced), 2 seam
samples.
- 30-mil EPDM (fabric-reinforced), 2 seam samples.
- 30-mil LLDPE (unreinforced), 2 seam samples.
- 30-mil HOPE (unreinforced), 1 seam sample.
- 80-mil HOPE (unreinforced), 3 seam samples.
- 30-mil PVC (unreinforced), 5 seam samples.
- 30-mil PVC/CPE (unreinforced), 1 seam sample.
Tne specific seaming procedures used in preparing the samples evaluated in
the test program are indicated in Table 5-55. Test slabs from some of
the seam samples were also immersed and tested for changes in weight and
thickness. The immersion media were:
Chemical Concentration8, % Type
Phenol 10 Organic acid
Hydrochloric acid 10 Inorganic acid
Sodium hydroxide 10 Inorganic base
Methyl ethyl ketone 10 Ketone
Furfural 5 Aldehyde
Methylene chloride 100^ Halogenated hydrocarbon
NaCl at 23°C 36.1 (saturated) Brine
NaCl at 50°C 37.0 (saturated) Brine
Water 100 Tap water (Denver, CO)
aParts per 100 parts of water, by weight.
methylene chloride.
5-113
-------
TABLE 5-55. SEAMING PROCEDURES USED TO PREPARE SAMPLES3 FOR IMMERSION IN TEST SOLUTIONS
Miscellaneous
Thermal
Polymer
CPE
CSPE
EIA
EPDM
HOPE
LLDPE
PVC
PVC/CPE
FML
Type of
compound
TP
TP
TP
XL
CX
CX
TP
TP
Dual Extrusion
hot weld Solvent Vulcanized
Hot air
Fabricb (THA)C
U
R 1,2
R 3,4,5,6
R 9,26
R
U
U
U
U
Dielectric
(TDI)c
12
...
8
* • •
...
...
...
15
16
Hot wedge wedge Fillet Lap Neat
(THW)C (TDW)C (EFW)C (ELW)C (SA)C
11,28,29
18
*•• ••• •»• ••• £ 0 y &*r
••• »•» •*• ••• c5
33 30,31 32
13,34
* » • ••» »•• •*• 1" j JO j
36,37
• •• ••• *•• •*• •••
Bodied cap strip
(BSA)c (VZ)C
* • * • • •
17
7,19
20,22
10
...
• • • * • •
• • • • * •
...
With
gum
tape
and
cement Adhesive
(GTC)C (AD)c
• • • * • *
• • • * • •
21
• * • • • •
27
• • • « • *
...
• * » • • •
...
aNumbers reported in table are seam sample identification numbers.
bU = unreinforced; R = fabric-reinforced.
cAuthors' code for identifying seaming procedure used in preparing samples.
Source: Morrison and Parkhill, 1987.
-------
Methylene chloride is only slightly soluble in water (2.0 parts per 100 parts
water at 20°C); therefore, neat solvent was used to avoid the problem of
phase separation. Pure chemicals or aqueous chemical solutions were selected
for testing rather than simulated or actual wastes from waste sites, to
simplify verification of testing procedures. The use of one- or two-compo-
nent chemical solutions also simplified interpretation of the data.
The tests that were performed on the seams fabricated from the different
FMLs by the different methods or on small coupons of the individual FMLs
included:
- Weight change to 52 weeks.
- Thickness change to 52 weeks.
- Shear strength.
- Peel strength.
- Dead weight load test.
The changes in weight of the FML samples immersed in the various test liquids
for 52 weeks are presented in Table 5-56.
Some of the significant effects of immersion in these liquids were:
-All of the FML samples that were thermoplastic dissolved or dis-
integrated in the methylene chloride. The one FML that was cross-
linked (EPDM) and the six semi crystal line FML samples swelled.
- Weights of several samples went through a maximum, indicating swell-
ing; went through a minimum, indicating extraction; then began swell-
ing again. An example of this is the behavior of PVC samples in
furfural which is presented in Figure 5-32.
- The aqueous organics at the concentrations used in this test program
resulted in considerable changes in the weight of the thermoplastics,
either because of swelling or extraction.
- Several of the samples did not reach an equilibrium by the end of 52
weeks, as is shown in Figure 5-32. These results indicate that with
aqueous solutions, such as waste liquids, exposure periods longer
than the 120 days used in EPA Method 9090 (EPA, 1986) are necessary to
determine the effects of immersion.
The results of the peel and shear tests of the immersed seams are
summarized in Table 5-57. These results indicate that some organics have a
severe effect on the FMLs and their seams; also, they indicate the aggres-
siveness of the NaOH solution.
5-115
-------
TABLE 5-56. CHANGE IN WEIGHT OF FMLS EXPOSED TO VARIOUS TEST LIQUIDS FOR 52 WEEKS3
CTl
Change, percent by
Polymer
CPE
CSPE
EIA
EPDM
HOPE
LLDPE
PVC
Sample0
L
M
A(R)
B(R)
C(R)
D(R)
E(R)
F(R)
G(R)
H(R)
I(R)
J(R)
K(R)
N
0
P
Q
R
S
T
U
Type of
compound11
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
TP
XL
CX
CX
CX
CX
CX
TP
TP
TP
Nominal
thickness
mil
30
30
36
36
30
36
36
36
36
36
36
38
30
30
80
80
80
30
30
30
30
Tap
water
10.19
9.78
22.10
9.27
4.06
8.10
5.81
6.77
4.92
5.12
11.72
4.03
3.55
-0.01
0.05
0.01
0.06
0.00
1.57
2.42
1.53
Saturated
NaClb
23°C
1.41
1.27
2.37
1.20
0.65
2.23
3.00
1.27
2.46
2.46
2.96
1.81
1.55
-0.01
0.06
0.01
0.02
0.07
-0.97
-0.81
-0.18
50°C
1.10
1.99
3.09
0.48
1.74
4.45
4.46
3.29
2.96
2.73
4.15
2.38
2.94
0.14
0.13
* • •
0.00
0.27
-0.54
-0.57
-0.50
10%
Phenol
25.61
25.88
37.11
6.10
14.53
16.54
17.54
38.04
16.64
16.68
19.03
-100.00
8.61
-0.48
0.12
-0.01
-0.41
-0.50
-16.38
-15.90
-12.78
10%
HC1
1.41
1.24
9.47
-0.22
0.60
2.90
2.68
6.04
9.15
3.68
20.15
7.12
3.76
-0.28
-0.29
-0.31
-0.26
-0.79
6.41
3.69
7.04
10%
NaOH
-2.07
-2.22
8.25
-5.37
1.20
2.25
2.15
3.60
14.05
14.59
11.94
-5.22
1.29
0.32
0.19
0.12
0.14
0.21
-18.11
-19.65
-14.97
weight
10%
MEK
29.89
38.63
18.25
12.72
4.60
16.01
7.25
10.19
6.30
6.47
14.82
5.77
4.74
0.39
0.55
0.18
0.28
0.63
2.91
5.51
11.37
100%
CH2C12
-100.00
-100.00
-100.00
-100.00
-100.00
-100.00
-100.00
-100.00
-100.00
-100.00
-100.00
-100.00
4.03
6.74
4.07
3.17
4.78
7.52
-100.00
-100.00
-100.00
5%
Furfural
67.60
80.00
47.81
24.92
14.99
23.89
18.09
38.55
17.43
17.76
22.01
32.30
11.80
0.83
0.59
0.34
0.51
0.72
5.55
13.12
15.35
aAll solutions are aqueous; exposure was at room temperature (23°C), except where otherwise indicated.
A "5%" or "10%" solution means 5 or 10 g of solvent per 100 g HgO, respectively. Methylene chloride was neat.
bSaturated solution at 23°C is 26.5% by weight (36.1 g per 100 g H20); saturated solution at 50°C is 27.0% by
weight (37.0 g per 100 g HZ0).
cldentification code; R = fabric reinforced.
dTP = thermoplastic; XL = crosslinked; CX = semicrystalline thermoplastic.
Source: Morrison and Parkhill, 1987, pp 81-85.
-------
60r
PVC - Sample S in Furfural Solution
PVC - Sample S in MEK solution
-10
\ -^-* - "
s-*"
0 10 20
i i
30 40
i
so a
Time, weeks
Figure 5-32. Change in weight of a
solutions as a function of
hill, 1987, p 84).
PVC immersed in furfural and MEK aqueous
time. (Source: Morrison and Park-
5.4.3 Compatibility Testing of FMLs
The compatibility of a candidate FML with the waste to be contained is
an essential consideration in making the final choice of an FML for use as a
liner in a waste storage or disposal facility. In view of the vast variety,
complexity, and uncertainty of the compositions of the waste liquids and
leachates that must be contained, a test was needed to assess the compati-
bility of a candidate liner with the specific waste liquid to be contained.
A method was suggested in the 1983 edition of the EPA Technical Resource
Document, "Lining of Waste Impoundment and Disposal Facilities" (Matrecon,
1983). Later in 1983, the EPA proposed a test method for determining the
compatibility of wastes and FMLs. This method, which was noticed in the
Federal Register (EPA, 1984), has been revised extensively and was recently
published in SW-846 as Method 9090 (EPA, 1986). The current version of
Method 9090 is presented in Appendix L.
5-117
-------
TABLE 5-57. PERFORMANCE OF FHL SEAM SAMPLES EXPOSED TO VARIOUS TEST LIQUIDS'
cn
i
oo
Test liquid1'
Polymer
CPE
CSPE
E1A
EPDM
HOPE
UDPE
PVC
PVC-CPE
Sample^
L
L
H
H
A(R)
A(R)
B(R
B(R)
C(R)
C(R)
D(R)
D(R)
E(R)
E(R)
F(R)
F
-------
Method 9090 attempts to simulate some of the conditions that an FML
may encounter in service and to determine the effects on an FML of contact
with a waste liquid. In this exposure test, samples in slab form are im-
mersed for up to four months at 23° and 50°C in a representative sample of a
waste liquid or leachate. A number of physical and analytical tests are
performed on the unexposed FML for baseline data and on samples after expos-
ure to the waste liquid for 30, 60, 90, and 120 days. Consequently, the test
procedure is complex and involves many steps including selecting representa-
tive samples of both the waste to be contained and an FML for testing,
exposing the FML samples to the waste under highly controlled conditions,
physical testing and analysis of unexposed and exposed FML samples, and
interpreting the final results.
Developing a reliable compatibility test requires determining and
assessing those factors that can affect test results and result in errors.
Ideally, a test should be relatively simple and yield results that are
accurate and precise. A factor of particular importance in this test is the
control of the composition of the sample of waste liquid and the effect that
lack of adequate control may have on an FML in the test. It is recognized
that a single representative sample of waste liquid must be used to conduct
the test and that the composition of this sample may not reflect the actual
composition of the waste liquid as a function of time.
Of particular concern is the effect of trace organics on FML-waste
compatibility. Haxo et al (1985b) reported the results of immersing FML
samples in a dilute (<0.1%) but saturated solution of tributyl phosphate (see
Section 5.4.2.2). Even at this low concentration, samples of CPE, CSPE,
neoprene, and PVC FMLs gained significant amounts of weight. These results
indicate that an FML can absorb large quantities of an organic from a leach-
ate containing only a trace concentration. The effect this tendency to
absorb trace concentrations has on FML permeability has been studied by
August and Tatsky (1984) and Haxo et al (1988). The results of these
studies indicate that an organic in a dilute aqueous solution will partition
or distribute itself between the water in which it is in solution and an FML
until equilibrium is reached and that the organic will permeate the FML at a
much higher rate than would be expected from knowledge of the permeation rate
of the neat organic and its concentration in the dilute solution (see Section
5.4.1.6.2).
In actual service in a waste containment unit the liquid that may
contact a liner is generally a dilute solution of water and various dissolved
constituents, some of which are inorganic and others organic; the latter can
be either volatile or nonvolatile, or both. The concentrations of the
constituents will probably be low and more or less constant, or will change
only slowly with time. In performing laboratory testing of an FML to assess
its compatibility with a waste liquid, it is desirable to simulate as much as
possible the conditions that exist in service. Inasmuch as the amount of
organics that is absorbed by an FML affects its properties, the concentra-
ations of the organics in the solution to which it is exposed should remain
essentially constant.
5-119
-------
It is not known what effect minor variations in waste composition would
have on the test results. Using synthetic hazardous waste leachates is one
method that has been suggested for verifying the compatibility of an FML in
cases where no actual leachate is available. To develop a synthetic leach-
ate, thorough analyses have been performed on actual hazardous waste leach-
ates to determine their composition, and particularly to identify the organic
constituents that are present (Bramlett et al, 1987; McNabb et al, 1987), as
is discussed in Section 2.2.4. The results of these analyses indicate the
wide range of organic constituents present in the leachates and the dif-
ficulty in identifying them. Because so little is known about the inter-
action between FMLs and unidentified trace organics, using a synthetic
leachate to verify compatibility of an FML and a leachate leaves many
questions unresolved.
In addition, even during the course of testing, changes that would not
reflect the actual composition in service can occur in the composition of the
representative waste liquid sample. In the case of solutions containing
volatile organics, the organics could be absorbed by the FML or could escape
from the test tanks. In either case, a lower concentration of organics in
the test liquid would results.
Because of the limited duration of exposure, it is also desirable to
refine the test to be able to project longer exposure times and, possibly,
service life. Tests of properties that would reflect the long-term perform-
ance, serviceability, and durability of an FML in service more accurately
than those tests presently in Method 9090 should also be investigated and,
if possible, incorporated into the method.
The results of immersion tests performed by Bellen et al (1987) and
Morrison and Parkhill (1987) showed that some FML samples, particularly some
of those that were immersed in aqueous solutions of organics, did not reach
equilibrium swelling after 52 weeks of exposure. These results indicate that
the 120-day maximum exposure time in Method 9090 may not be a sufficient
length of time for tests with aqueous solutions.
The EPA is in the process of developing expert systems to use in evalua-
ting FML-waste compatibility data generated in a Method 9090 liner compati-
bility test (Rossman and Haxo, 1985). These systems are applicable to PVC,
HOPE, and CSPE FMLs. One such system is the Flexible Liner Evaluation Expert
(FLEX) computer program, which is available in draft form from the EPA (see
Section 7.5.3.2.1.2).
The following subsections present results of research performed by Haxo
et al (1988) on compatibility testing with particular reference to EPA Method
9090. The objective of this research was to establish the magnitude of some
of the factors that can affect Method 9090 test results and to develop
information that will aid in the interpretation of the test results. As
presently written, Method 9090 is designed to assess the changes in selected
properties that take place in samples of an FML that have been immersed in a
specific waste liquid. At the present state of knowledge, there is a lack of
information about FMLs in service with respect to the type and degree of
5-120
-------
changes in properties obtained in EPA Method 9090 tests which would indicate
that a given FML is acceptable for use as a liner for the long-term contain-
ment of the waste liquid or leachate used in the test. However, results from
the test can be used to demonstrate that a specific combination of an FML and
a waste liquid is incompatible and that the FML should not be used as a liner
to contain that particular waste.
5.4.3.1 Compatibility Testing Performed with Actual and
Synthetic Leachates Containing Organics—
Haxo et al (1988) monitored the level of organics in the test solutions
and in the FML specimens in two EPA Method 9090 tests that were performed
with actual and synthetic leachates. In particular, they studied:
- Changes in the composition of the waste liquid during an exposure due
to absorption of organics by the FML specimens.
- The loss of volatile constituents from aqueous waste liquids during
exposure, and the level of control required to prevent the volatiles
from escaping from the exposure tanks.
- The effect of temperature on the level of control required to maintain
concentration levels of the waste constituents during exposure.
- Whether replacement of waste liquids during testing is a feasible
means of maintaining concentration levels of the waste constituents
during exposure.
The overall approach in performing this research was:
- To basically follow EPA Method 9090, as noticed in the Federal Regis-
ter of October 1984. Additional tests that appeared to be appropriate
for this study were also included.
- To use exposure tanks that do not absorb or permeate volatile or
nonvolatile organics. No. 316 stainless steel was selected for
fabricating the tanks; Teflon gaskets were used in sealing the covers
to the test tanks to prevent loss of volatiles.
- To follow the compositions of the waste liquids by GC analysis and to
analyze the exposed FMLs for volatile organics by headspace GC and for
nonvolatiles by extraction and GC analyses of the extract.
- To conduct several simple tests to determine whether volatiles had
been lost in the various steps of the compatibility test, i.e. whether
volatiles had been lost from the waste liquid or from FML samples that
had absorbed volatile organics.
- To spike actual leachates and water with volatile and nonvolatile
organics typically found in the actual waste liquids and track their
movement by GC analyses.
5-121
-------
At present, EPA Method 9090 does not indicate the materials out of which
the exposure tanks should be fabricated. It does indicate that the tanks
should be equipped so that there is no evaporation of any of the solutions
and suggests that they should be equipped with a reflux condenser. Because
of the chemical resistance of polyethylene and polypropylene, tanks made of
these materials have been used. Both materials appear to be satisfactory for
testing the compatibility of FMLs with leachates that only contain dissolved
inorganics. However, in tests with waste liquids or leachates that contain
volatile or nonvolatile organics, the walls of the tank can compete with the
FML under test for the organics present. Furthermore, the walls are perme-
able to the organics. Competition between the tank walls and an FML for
organics is particularly a problem when an FML material similar in composi-
tion to the tank walls is being tested, e.g. when the FML and the tanks are
both polyethylenes. To avoid this competition, a steel exposure tank that
incorporates a Teflon gasket between the cover and the top of the tank was
designed and fabricated.
A schematic of the tank used in the compatibility testing performed in
this study is presented in Figure 5-33. The tank has the following features:
- The tank, stirrer, and sample rack are constructed of 316 stainless
steel.
- The volume of leachate or exposure liquid held by a tank is 5.2
gallons (19,682 ml).
- A Teflon gasket is installed between the tank lid and the flange
around the top of the tank. The gasket is used to prevent loss of
volatiles; Teflon was selected to minimize absorption of leachate
constituents by the gasket.
- A stirrer can be operated continuously to prevent stratification
within the waste liquid.
- Each tank can be operated at 23° or 50°C. Temperature is monitored
with a mercury thermometer, as well as with a thermocouple sensor
monitored by a data logger. The data logger also serves as a second-
ary temperature control system that will turn off the heating system
should the temperature rise beyond pre-set limits.
- The tank is heated by heaters attached to the outside of the tank in
an area near the stirrer.
- Two short standpipes are secured in the lid of each tank and used for
filling the tank to its capacity, thus minimizing the possibility that
volatiles will leave the leachate to enter a headspace.
- Each lid is equipped with a septum through which sampling or spiking
of leachate can be performed.
5-122
-------
THERMOMETER
SEPTUM FOR
SAMPLING
LIQUID
GEAR-MOTOR
VENT/DRAIN
TUBE
LID
TEFLON
GASKET
LINK LOCK
316 STAINLESS
STEEL TANK
TEMPERATURE
CONTROLLER
SPECIMEN
HOLDER
HEATER
Figure 5-33.
Schematic of
studies with
1988, p 78).
the exposure tank used in
spiked leachate and water.
the FML compatibility
(Source: Haxo et al,
5.4.3.1.1. Compatibility test of an HOPE FML performed with an actual
leachate spiked with selected orgram'cs--Ashort-termexploratory compati-
bility test was performed on a polyethylene FML with a leachate that had been
obtained from a hazardous waste landfill and was spiked with a group of
volatile organics. Spiking a leachate with constituents that are or may
be in a leachate was considered to be a means of accelerating a compatibility
test since it would increase the severity of the exposure conditions. In the
context of the research project, it was also desirable to introduce known
species of organics which could be absorbed by the FML from dilute aqueous
solutions and tracked relatively easily by GC. The availability of a waste
that contained volatiles provided the opportunity of running a short-term
test to assess the effects of the volatiles and to observe possible loss of
volatiles during testing. The organics used to spike the leachate included
the following:
- Trichloroethylene.
- 1,1,1-Trichloroethane.
- Benzene.
5-123
-------
- Toluene.
- o-Xylene.
- m-Xylene.
- p-Xylene.
The concentrations of the organics in the FML were monitored by headspace gas
chromatography (HSGC), which is described in Section 4.2.2.5.1 (p 4-94).
The results of this experiment showed the importance of maintaining the
volatiles content in the exposure tanks. Even with excessive amounts of the
organics, the volatiles were lost from the tanks. Increases in the weight of
the slabs and in their volatiles content after three weeks of exposure to the
spiked leachate indicated significant absorption of the volatile components
of the spiked leachate. These increases were accompanied by significant
changes in some physical properties. For example, there were significant
losses in tensile at yield, tensile strength, modulus, puncture resistance,
and hardness. When the slab was returned to the tank and allowed to continue
in exposure after the 27th day, the volatiles content dropped substantially
and the properties returned closely to baseline values. This return to
baseline values indicates that most of the property changes that occurred in
the early part of the test were due to swelling. It should be noted that the
Teflon gasket, which, in the procedure performed by Matrecon, is normally
replaced at the end of each test interval, was not replaced in this test as
it appeared to be in good condition at the end of 20 days of exposure.
It was concluded that at each time interval when the tanks are opened to
recover the samples for testing, the leachate should be replaced with fresh
liquid that has been kept in sealed drums. Furthermore, the gasket should be
changed, and the sealing surfaces of the cover and the metal container should
be checked carefully.
5.4.3.1.2 Compatibility test of an HDPE FML performed with PI water
spiked with organics--A second EPA Method 9090-type test was performed on an
HDPE FML using spiked DI water to form a synthetic leachate that contained 11
different organics, both volatile and nonvolatile (Haxo et al 1988). The
organics that were selected included the seven of the volatile organics used
in the compatibility test described in the previous subsection. Two addi-
tional volatile organics were included in the spiking solution, i.e. acetone
and methyl ethyl ketone (MEK), as were two nonvolatile organics that are used
as plasticizers for PVC and other polymers, i.e. tri-n-butyl phosphate (TBP)
and di(ethylhexyl) phthalate (DEHP). Because TBP and DEHP have a higher
molecular weight, they would be absorbed more slowly by the HDPE. The
concentrations of the volatile constituents were monitored by HSCG, and the
concentrations of the nonvolatile organics by GC analysis of the extract.
The objectives of this experiment were:
- To perform an EPA 9090-type liner compatibility test with a test
liquid consisting of DI water with a "spike" that contained 11
5-124
-------
organics which included seven used in the earlier EPA 9090-type test
performed for this project.
- To assess the effect of temperature on exposure, i.e. 23° and 50°C.
- To determine the changes in concentration on the organics in the
liquid using GC and to compare the results with the amounts of the
organics absorbed by the HOPE samples. These amounts would be de-
termined by headspace GC of the FML samples.
The test data on the volatiles and weight changes indicated that there
were significant losses in volatiles from the test system as the test pro-
ceeded. These losses were reflected by the relatively insignificant changes
in the physical properties at the end of the immersion. The GC analyses
showed that the concentrations of all of the volatile organics dropped, both
in the exposed FMLs (after initially absorbing a relatively high concentra-
tion) and in the water, indicating a relationship between the concentration
of the organics in the water and in the FML. The results of the HSGC analy-
ses of the FML samples are presented in Table 5-58. The increase in extract-
ables indicated that the two plasticizers incorporated in the original
test liquid were gradually absorbed by the FML samples, which was confirmed
by the GC analyses of the extracts (Table 5-58). Whereas the results of the
previous Method 9090 test performed for this project indicated that an
increase in volatiles content can affect the physical properties of an HOPE
FML, the results of this test indicated that an increase in extractables did
not appear to affect the physical properties of the exposed HOPE samples.
The net results indicate the importance of the effects of volatile organics
on the properties of a polymeric FML.
It is concluded from the results of this experiment that tight control
of volatiles in an EPA Method 9090 test is essential, and that the con-
centration of all constituents in a leachate used in a compatibility test
must be maintained at original levels.
The data also indicated that "synthetic leachates" require more develop-
ment in order to be used in liner-waste compatibility testing. It appears
that addition of a spiking of a few volatile organics to water to yield a
"leachate" is not sufficient and that a broader background of organics is
needed. It should be noted that, in the test using spiked leachate, the
volatile organics in the spike plus organics in the original leachate had
greater effects on the properties of an FML than did essentially the same
volatile organics alone when added in the spike.
The loss of volatiles at the higher exposure temperature resulted in
higher retention of properties than at the lower exposure temperature,
probably a result of the evaporation of volatile organics. These results
indicate problems in performing a Method 9090 test at 50°C and higher.
5-125
-------
TABLE 5-58. GC ANALYSIS OF THE EXPOSED FML SAMPLES
en
i
ro
Exposure
temperature,
tank number, i
and time
Tank I (23°C)
34 days
69 days
105 days
139 days
Tank III (23°C)
34 days
69 days
105 days
139 days
Tank II (50°C)
34 days
69 days
105 days
139 days
Tank IV (50°C)
34 days
69 days
105 days
139 days
Volatiles in FML by Headspace gas chromatography, mg g~l
Acetone
(1973)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
MEK
(2013)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1,1,1-TCA Benzene
(326a) (2313)
1.42
0.45
0.25
0
0.68
0.18
0.08
0.02
0.1
0.01
0
0
0.10
0
0
0
0.46
0.18
0.04
0
0.30
0.05
0.01
0.00
0.02
0
0
0
0.11
0.01
0
0
TCE
(4063)
1.58
0.98
0.21
0
1.26
0.30
0.07
0.01
0.16
0.08
0
0
0.40
1.01
0
0
Toluene
(3383)
2.63
1.75
0.34
0.02
2.25
0.81
0.16
0.05
0.66
0.05
0
0
0.96
0.03
0
0
m- and p-
Xylenes
(1913)
1.86
4.17
1.85
0.19
1.33
3.00
1.26
0.08
0.78
1.06
0.17
0
1.29
0.82
0.10
0
GC i
extractables,
o-Xylene
(1033)
1.17
1.53
0.82
0.04
0.80
1.03
0.53
0.00
0.57
0.46
0.14
0
0.83
0.37
0.11
0
Total
8.72
9.06
3.51
0.25
6.62
5.37
2.11
0.16
2.29
1.66
0.31
0
3.69
2.40
0.21
0
TBP
(2513)
0.32
5.62
6.44
• * •
0.08
0.52
5.29
• • •
1.61
3.34
9.47
• • *
1.53
5.31
7.57
* • •
DEHP
(2503)
0.11
0.41
0.63
• • •
0.08
0.14
0.32
• • •
0.31
0.42
0.64
• * •
0.26
0.42
0.52
* • •
of
mg g-1
Total
0.43
6.03
7.07
• • •
0.16
0.66
5.61
• • •
1.92
3.76
10.11
• • •
1.79
5.73
8.09
• • •
aTotal concentration in mg L"1 of the orgam'cs injected in the water in two portions. Value assumes complete
dissolution in the water.
Source: Haxo et al, 1988, p 96.
-------
5.4.3.2 Evaporation of Volatile Organics from Water
Solutions and Exposed FMLs—
In testing an exposed FML and insofar as the amount of organics that
is absorbed by an FML affects its properties, the concentrations of the
organics in the FML must remain essentially the same as they were when the
FML was in exposure. As the volatile components can evaporate relatively
easily, FML samples that are being recovered and tested should be protected
from loss of volatiles. A loss of volatiles can result in values for many
properties different from values for the properties of the FML as it existed
at the time it was removed from service.
The effects of exposing an FML to a service environment can be of one or
more of three basic types:
- Degradation of the polymer itself, either by reduction in molecular
weight or by crosslinking, either of which could cause drastic changes
in properties.
- Extraction of plasticizers or other compounding ingredients in the
FML. This can result in a variety of effects including hardening and
loss of antioxidants and other antidegradants which could result in
faster rates of degradation of the polymer.
- Swelling of the FML due to absorption of organics and water. In this
case, exposure may result in loss of physical properties and increases
in permeability. The evaporation of volatile absorbed constituents
may result in recovery of many of the baseline values of the FML;
consequently, the effects of the exposure, which would be observed at
the time a sample is removed from service, are lost. It would be
ideal if the testing of an FML specimen could be performed while it is
immersed in a waste stream as is sometimes done in the testing of the
compatibility of rubbers and plastic compositions with various sol-
vents, oils, and other fluids.
It is the third type of effect which is of particular concern in testing FMLs
that have been in contact with waste liquids that contain minor amounts of
organics. To demonstrate some of the effects resulting from the evaporation
of volatiles, either from the test tank in which the FMLs are being exposed
in an EPA Method 9090-type test or from the loss of volatiles after removal
from immersion, several experiments were performed by Haxo et al (1988);
these are described in the following subsections.
5.4.3.2.1 Evaporation of volatile organics from aqueous solutions--The
evaporation of several volatile organics from dilute aqueous solutions was
measured. These measurements were made by preparing 200 mL solutions of
various types of organics in concentrations ranging from 200 to 10,000 mg L~^
in 400 mL beakers. The beakers were left uncovered and the organics were
allowed to evaporate. The concentrations of the organics remaining in the
beaker were monitored by GC analysis. The results showed a pronounced loss
5-127
-------
from the solutions for all of the organics, particularly the aromatic hydro-
carbons toluene and xylene. Selected results are presented in Figures 5-34
and 5-35. The comparative rates of loss are illustrated in Table 5-59,
in which the times to one-half of the initial concentrations are presented.
1350
300
600 900
Time, minutes
1200
1500
1800
Figure 5-34.
Reduction in concentration of TCE in a dilute aqueous solution
of initial concentration of 1100 mg L~l by evaporation from an
open beaker at room temperature. 200 ml of solution was in a
400 ml beaker. (Source: Haxo et al, 1988, p 104).
These results indicate the need when conducting compatibility tests to
take precautions to prevent the loss of volatiles from the time a waste
liquid is received for test through the four months of exposure. These data
also indicate the need to prevent loss of the volatiles from the time the
waste liquid is collected through shipping and testing. The results confirm
the data that were obtained in the two EPA Method 9090-type tests which are
described above.
5.4.3.2.2 Evaporation of organics from saturated FML specimens—The
loss of volatiles from exposed FML samples was demonstrated in a series of
tests with HDPE and various organics. Typical results are shown in Figure
5-36 for toluene, TCE, and a mixture of organics that were absorbed by
small samples of a 100-mil HDPE FML. Again, there was rapid evaporation of
the volatile constituents when a sample was withdrawn from the organic. The
5-128
-------
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of evaporation of a volatile organic or water from an FML sample is affected
by the type of organic, the test temperature, air movement, and sample size,
thickness, and shape. It should be pointed out that even during physical
testing, such as tensile testing, the specimens lose volatiles. This loss
may be a factor due to the duration of the test and the increased surface and
reduced thickness of the specimen during the actual physical testing.
24
22 -
20
18
16
14
ul
0.
§ 12
o
o>
c
''S 10
I I I I
Trichloroethylene
Toluene
Equal weight mixture of acetone,
MEK, trichloroethylene, trichloroethane, _
benzene, toluene, o-xylene, p-xylene,
and m-xylene.
.1.
4 5
Time, hours
Figure 5-36.
Loss of organics from HDPE FML samples saturated with different
organics. (Source: Haxo et al, 1988, p 106).
5.5 EFFECTS OF MECHANICAL STRESS
To function within an engineered system, FMLs and other components of
a liner system must be able to maintain their integrity after exposure to
mechanical stresses. Short-term mechanical stresses can include stresses
during installation such as those caused by placement of the soil cover and
dropped tools, stresses caused by thermal shrinkage, and stresses related to
the weight of the materials placed on top of the liner system. Long-term
5-130
-------
mechanical stresses are most often the result of the weight of the mate-
rials on top of the liner system or differential settlement of the subgrade.
Various attempts have been made to simulate the effects of mechanical
stresses on FMLs and ancillary components of a liner system. The following
subjects are discussed in this section:
- The ability of an FML to conform to a subgrade.
- The leakage rates through holes in FMLs.
- The effect of compressive stresses on the hydraulic transmissivity of
geonets and geotextiles.
5.5.1 Large-Scale Hydrostatic Testing Over a Subgrade
Various testing devices have been developed that simulate the in-service
behavior of an FML under hydrostatic pressure to evaluate the ability of an
FML to conform to irregularities in a subgrade, which is an important feature
in the design of a facility. Irregularities such as cracks, rocks, and voids
can cause localized settlement of the subgrade and result in puncture of the
FML. Various types of test subgrades have been used in an exploratory fashion
to simulate the following situations:
- Bursting over interstitial spaces in a subgrade.
- Puncture over protrusions in an uneven subgrade.
- Bursting related to settlement of the subgrade.
- Bursting related to damage caused by placing a load on a soil or
gravel cover material that has been placed on an FML.
Using geotextiles to protect an FML has also been investigated.
As an example of a typical testing device, a schematic of the testing
device vessel developed by the Bureau of Reclamation is presented in Figure
5-37 (Frobel, 1981 and 1983). In this device, hydrostatic head and loading
rates were simulated by a compressed air-on-water pressurization system. The
compressed air-on-water system was preferred over a water pressure system to
improve pressure control and to increase the range of operating pressures,
i.e. to increase the maximum hydrostatic head. Maximum design pressure was
1034 kPa (150 psi) which is equivalent to approximately 105 m (350 ft) of
head. Actual maximum pressure was limited by line pressure. The vessel top
and bottom sections were fabricated from 500-mm (20-in.) outside-diameter
pipe. Each vessel provided approximately 0.2 m^ (300 in.2) of surface
area for FML testing. To provide versatility in removing and installing test
subgrades, the vessels were designed to accommodate interchangeable subgrade
pans. The'pressurization of the vessels was controlled and monitored during
testing by a computer.
5-131
-------
Morrison and Starbuck (1984)
samples of 20-, 30-, and 45-mil PVC
subgrades:
reported the results of testing unaged
at the Bureau of Reclamation over three
Four Plexiglass pyramids placed in sand. These pyramids, similar to
those developed by Rigo (1977), were used to attempt a reproducible
puncture-type subgrade configuration. The pyramids have equilateral
bases measuring 100 mm (4 in.) on a side and a height of 70 mm (2.75
inches). The tops of the pyramids are truncated 1 mm (0.04 in.) below
the apex. The pyramids were surrounded with sand, the depth of which
could be varied to give different pyramid heights.
Five plastic pipes of varying diameters simulating interstitial voids.
The diameters of the pipe ranged from 25 mm (1 in.) to 75 mm (3
inches). The open end of the pipes were level with a sandy subgrade.
Pressure Relief Valve
Female Quick-Connect
(so le noid-valve-controlled
air input)
Vent Valve —.
Pressure Gage
Female Quick-Connect
/ (transducer output)
* »•
Fill/Drain Valve
"O" Ring
Piston Guide
"O- Ring
. Subgrade Pan
• Pan Lifting Piston
Pan Support Ring
BOTTOM SECTION
Pressure Relief Valve
and Wiring Input for Electrodes
\
Male Quick-Connect
(pressure switch output)
Drain Valve
Figure 5-37. Detailed section through a hydrostatic testing vessel
(Based on Frobel, 1981, p 10).
5-132
-------
The air pressure in these tests was raised incrementally 6.9 kPa (1 psi)
every 30 minutes. Water temperature was maintained between 21.1°C (70°F) and
23.3°C (74°F). Test results are summarized in Table 5-60. These results
indicated that of the three subgrades used, the one simulating interstitial
voids was the most severe.
TABLE 5-60. HYDROSTATIC RESISTANCE OF THREE PVC
FMLS OVER THREE DIFFERENT SUBGRADES*
pvc Time to
thickness Jest failure, Maximum pressure
mm mils subgrade^1 min. kPa lb/in.2
Remarks
0.51 20 Cylinders 570 137.9
0.76 30 Cylinders 995 234.4
1.14 45 Cylinders 1189 286.1
0.51 20 Pyramids ... 503.3
0.76 30 Pyramids
1.14 45 Pyramids
0.51 20 Gravel
0.76 30 Gravel
1.14 45 Gravel
875.6
... 875.6
503.3
2710 675.7
834.3
20.0 Failed on 75-mm (3-in.)
cylinder
34.0 Failed on 75-mm cylinder
41.5 Failed on 75-mm cylinder
73.0 No failure at maximum
1ine pressure
127.0 No failure at maximum
setting on pressure
booster
127.0 No failure at maximum
setting on pressure
booster
73.0 No failure at maximum
line pressure
98.0 One pinhole
121.0 No failure at maximum
setting on pressure
booster
aWater temperature for all tests was maintained between 21.1°C (70°F) to
23.3°C (74°F).
^Cylinders: five plastic pipes with diameters of 25 mm (1 in.), 38 mm
(1.5 in.), 50 mm (2 in.), 60 mm (2.37 in.), and 75 mm (3 in.); pyramids:
four plastic pyramids with equilateral bases of 100 mm (4 in.) on a side
and a height of 70 mm (2.75 inches). The pyramids were buried in sand so
that they only had an effective height of 25 mm (1 inch); gravel: 9 to
19-mm (0.375 to 0.75-in.) size aggregate.
Source: Morrison and Starbuck, 1984, p 36.
5-133
-------
Frobel et al (1987) tested three thicknesses of LLDPE with and without
geotextiles and three thicknesses of HOPE in a testing device similar to the
Bureau of Reclamation device over varying heights of test pyramids embedded
in sand. The test pressure was raised 6.9 kPa (1 psi) every 30 min. of test
until failure occurred. The results of these tests, which are presented in
Table 5-61, indicate the effectiveness of using a geotextile to reduce the
susceptibility of an FML to puncture.
Fayoux (1984) performed hydrostatic tests of a series of FMLs in a
similar testing device using a subgrade consisting of a bed of crushed 20-40
mm quartzite stones. In these tests the pressure was inncreased incre-
mentally 100 kPa (14.5 psi) after each minute of test. Fayoux observed
that in general the thinner FMLs (e.g. 20-mil PVC) failed in areas where
there was a lack of support (i.e. in the spaces between the stones) whereas
the thicker, more rigid FMLs (all bitumens or polymer-modified bitumens)
tended to span these spaces and fail where the stones were pointed or had
sharp edges.
Steffen (1984) performed limited exploratory testing to determine the
effect of uneven subgrade settlement on the deformation and bursting strength
of FMLs. The testing device used was similar to those discussed except that
pressurization was performed by air alone and a means for allowing the sub-
grade materials to be drawn off was incorporated in the bottom of the test-
ing device. Steffen noted an uneven distribution of stresses across the
cross section of the deformation area.
Fayoux (1984) also tried to determine what effect the action of two
stones which are positioned on either side of an FML and which are under
static stress would have on an FML's integrity. This type of action can
occur when an FML is covered by granular materials. The important factors in
such a study include:
- Particle size and shape of subgrade material.
- Particle size and shape of cover material.
- Whether the FML is protected by a geotextile.
- The type and thickness of the FML.
- The stress applied from above to the cover material.
To perform these tests, an FML sample was placed in the base of a hydrostatic
tester and then covered with the cover material. The cover material was
pressed into the FML sample at a specific rate up to a predetermined load and
for a predetermined time. When the load was removed, the cover material was
taken off the sample, and the sample still in its base was tested for hydro-
static puncture. Limited results suggested that a 30-mil PVC FML was sus-
ceptible to puncture by fine limestone gravel (0-10 mm) which had been loaded
onto the FML at 300 kPa (43.5 psi) even when a geotextile was placed on one
side of the FML. Other results suggested the effectiveness of using a
geotextile to reduce an FML's susceptibility to puncture.
5-134
-------
TABLE 5-61. HYDROSTATIC PUNCTURE RESISTANCE TESTING OF HOPE FMLS AND LLDPE
FMLS WITH AND WITHOUT GEOTEXTILES OVER VARYING PYRAMID PROTRUSIONS
Pyramid height
FML system
Polymer
LLDPE
LLDPE
LLDPE
LLDPE
£ LLDPE
CO
LLDPE
LLDPE
LLDPE
LLDPE
HOPE
HOPE
HOPE
al psi =
Source:
Thickness,
mil
20
20
20
30
30
30
40
40
40
60
80
100
6.9 kPa.
Frobel et al ,
Geotextile
None
6 oz yd~2
12 oz yd'2
None
6 oz yd"2
12 oz yd'2
None
6 oz yd~2
12 oz yd'2
None
None
None
1987, p 574.
0.5
Fail
pressure,
4.1
21.4
213.9
6.9
69.0
345.0
19.9
158.7
441.4
17.3
26.6
40.6
in.
Fail
time,
min.
<2
95
930
15
308
1515
63
763
1930
75
116
176
1.0
Fail
pressure,
kPa
2.4
6.9
20.7
6.9
27.6
55.6
6.9
27.6
62.1
6.9
13.8
13.8
in.
Fail
time,
min.
<2
28
94
12
142
240
15
145
270
20
38
52
1.5 '
Fail
pressure,
kPa
1.6
6.9
13.8
4.8
27.6
41.4
13.8
22.1
62.1
6.9
6.9
6.9
in.
Fail
time,
min.
<2
12
34
<2
130
190
63
92
280
<2
12
28
-------
5.5.2 Holes in FMLs
In order to function properly, an FML liner must be installed and
placed into service free of flaws and holes through which liquid might
flow. The liner must be liquid-tight so that only gases and vapors permeate
on a molecular basis. The goal of improved design, materials, construction
techniques, and quality control/quality assurance is to cause the incidence
of holes in installed FMLs to approach zero and, at the same time, to build
in enough redundancy and backup in the design to prevent leakage out of the
containment unit if holes do occur. It is recognized that leaks in lined
facilities have occurred due to imperfect planning design, that punctures and
tears occur during construction and liner installation, and that there may be
failures resulting from uneven subsidence or other failure of the supporting
soil during service.
Because there was a lack of knowledge on leakage rates through flaws in
FMLs, a study was undertaken to evaluate the rate at which liquids leak
through flaws in the FML component of composite FML-soil liners (Brown et al,
1987). The flow of water through flaws of various sizes and shapes was
measured using specially constructed permeameters filled with gravel or soil
of known hydraulic conductivity. The variables that were studied included:
- Flaw size and shape.
- FML type and thickness.
- The presence or absence of a geotextile between the compacted
soil and the FML.
- The hydraulic conductivity of the soil base on which the FML was
placed.
- The liquid head.
- The liquid characteristics.
The soils were compacted in 60-cm diameter permeameters and overlain with the
FMLs to be tested. Round holes., slits, or seam flaws of different sizes were
incorporated in the FML samples.
A 15-cm layer of gravel was placed over the FML to provide ballast, and
a head chamber was used to apply as much as 100 cm of head on the FML. Tests
were also conducted with a permeameter that was modified to apply overburden
pressure, which is shown schematically in Figure 5-38, and a permeameter that
had a pressure vessel bolted to it so that the permeameter could approximate
a 10-m hydraulic head. Three different soil bases were used. A gravel
subbase was used to determine the flow rate allowed by the flaw without a
limiting subbase. Two soil bases having nominal conductivities of 1 x
10~4 cm s~l and 1 x 10~6 cm s~l were used to determine the effect of the
hydraulic conductivity of the base on flow rate. Tap water was the permeat-
ing liquid in most of the tests; however, limited testing was also performed
with a simulated MSW leachate and xylene waste, A mathematical model was
developed to simulate the flow rates through the permeameters and was modi-
fied to allow calculation of leak rates under field conditions.
5-136
-------
Springs
\
FML
Straight -
Sided Barrel
2.5 - cm Steel
Plate
Bolt
0.6 - cm Steel
Flange
Gasket
2.5 - cm Dia.
Outflow
Pipe
2cm
NOT TO SCALE
Figure 5-38.
Schematic diagram of a permeameter modified to apply overburden
pressure (not to scale). A 15 x 15-cm square of 0.3-cm mesh
screen was placed over the flaw to prevent gravel from blocking
flow. (Source: Brown et al, 1987, p 15).
The flow of liquids through flaws in FMLs was
dependent on the size and shape of the flaw, the
hydraulic conductivity ability of the soil base.
independent of the FML thickness, liquid properties
absence of an underlying geotextile.
found to be primarily
liquid head, and the
Flow rate was nearly
and the presence or
Variability in flow rates through seam flaws and slits was much greater
than that through round holes due to the variable cross-sectional areas that
5-137
-------
could result, depending on how much one side of the slit or the seam was
displaced relative to the other. The results indicated that the average leak
rates through the slit and seam flaws over a gravel base increased over
twelve-fold when the flaw length was increased from 5 to 15 cm.
One observation made during the study was that the liquid passing
through the hole spread laterally between the FML and the top of the com-
pacted soil. Under these flow conditions, the liquid will infiltrate into
the soil over a much larger area resulting in a higher leak rate. Figure
5-39 presents the two extremes of the flow patterns beneath a hole in an FML,
one in which there is no lateral flow beneath the hole, and the second in
which there is lateral flow in the gap between the liner and the soil. In
estimating leakage rates, it would be too conservative to assume that a seal
has been formed between the FML and the soil without a gap through which
lateral flow can occur. Thus, width was included in the mathematical model.
, FML Specimen
•*- Permeameter
Wall
(a) Flow pattern in which there is no lateral flow
between an FML and the soil base.
FML Specimen | ,,
Soil
Base
t
(b) Flow pattern in which there is complete lateral
flow between an FML and the soil base.
Figure 5-39. Flow patterns under the extreme conditions below a hole in an
FML. (Source: Brown et al, 1987, p 31).
5-138
-------
For soil bases, the head loss across the system may be divided into
the head loss as the liquid enters the hole, the head loss across the hole in
the FML, the head loss as the liquid flows laterally between the FML and the
soil, and the head loss through the soil. The amount of head loss caused by
the liquid flowing laterally between the FML and the soil depends on the
width of the gap between these two media. The gap widths for the 10-4 anc)
10~6 soils were estimated from the permeameter data to be 0.015 and 0.002
cm respectively. Thus, less permeable soils containing greater amounts of
clay form a better seal with the FML and restrict lateral flow of liquids.
Gap widths and resultant flow rates were also decreased by overburden pres-
sure from simulated layers of waste.
The results of the tests with the pressurized system indicated that
soil can erode just below a flaw in an FML, particularly when the liquid head
is large (e.g. in a lagoon) and when the base conductivity is greater than
10~6 cm s-l. This evidence of erosion caused by water flowing through
flaws in FMLs under elevated head is a serious concern, since erosion of the
soil base may result in stretching and the eventual rupture of the FML.
However, a geotextile placed below an FML can result in lateral flow of the
liquid and protect the soil from erosion. The mathematical model was
adapted to predict the conditions necessary for erosion to begin. It is
recognized that the model does not strictly represent an FML-soil liner in
which the compacted soil has an hydraulic conductivity si x 10~7 cm s~l,
but it illustrates the protection that a geotextile affords a soil below an
FML with a flaw.
5.5.3 In-Service Drainage Capability of Geotextiles and Geonets
Transmissivity is the property most often used to measure the in-plane
drainage capability of a synthetic drainage medium. ASTM D35 Committee on
Geotextiles, Geomembranes, and Related Products has developed a standarized
parallel flow test to measure hydraulic transmissivity (ASTM D4716). In this
type of test, a testing device provides a longitudinal flow path so that the
stream lines of flow through the drainage medium being tested are generally
parallel. A schematic of a parallel flow hydraulic transmissivity testing
device is presented in Figure 5-40. This type of device can be used to test
geonets, geocomposites, and geotextiles. An important factor in the in-
service drainage capability of a synthetic drainage medium is the normal
stress acting on the medium. The ASTM method determines hydraulic trans-
missivity under specified constant hydraulic head conditions and under
varying compressive stresses.
In a parallel flow testing device, and assuming laminar flow, hydraulic
transmissivity can be calculated as follows:
e =
where
8 = transmissivity (ft^ min.-l)
5-139
-------
q = flow rate (ft^ min.~l)
L = length (ft)
Ah = hydraulic head difference forcing flow (ft), and
W = width (ft).
W
Water
Reservoir i
J
'Base
Holes
I r
Normal Stress (an)
MittliHitiiiiitltliHi V
1 ~
^k~"~~> 1
i
i
L
Ah
i
'
Direction of Flow
-Specimen
Figure 5-40.
Hydraulic transmissivity testing device. Note the holes in
the water reservoir for controlling hydraulic head. (Source:
Carroll, 1987, p 19).
The derivation of this formula from Darcy's law is discussed in Section
4.2.5.3 (p 4-150). Thus, it can be seen that transmissivity is the rate of
flow (or discharge) per unit width per unit hydraulic gradient (Ah/L).
This section presents limited results of testing geotextiles and
geonets for hydraulic transmissivity.
5.5.3.1 Hydraulic Transmissivity of Geotextiles--
The range of drainage through geotextiles has been evaluated by Gerry
and Raymond (1983). The resulting typical values for transmissivity are
presented in Table 5-62. These results indicate that only the nonwoven-
needled geotextiles have appreciable in-plane flow capability and thus are
preferable in applications where in-plane flow is important. Koerner and
5-140
-------
Bove (1983) tested a number of commercially available nonwoven-needled
geotextiles. The results of these tests are summarized in Figure 5-41.
Koerner and Bove (1983) made the following observations:
- All fabrics show an exponentially decreasing trend due to initial
compression of these lofty fabrics at low stresses.
- All fabrics show a nearly constant transmissivity value at stresses
higher than approximately 19 kPa (400 psf) where the fiber structure
is sufficiently dense to support the applied stress.
- This constant, and residual, value is in the range of 0.40 to 1.4 x
10-6 m3/s'm (0.003 to 0.010 ft3/min*ft).
- There is considerable crossover of trends in the data from the various
geotextiles that were tested.
- There is, however, a general trend that the heavier and/or thicker
geotextiles have the highest transmissivity.
TABLE 5-62. TYPICAL VALUES OF DRAINAGE CAPABILITY
(IN-PLANE FLOW) OF GEOTEXTILES3
Transmissivity
Type of geotextile
Nonwoven-heat set
Woven-slit film
Woven-monofi lament
Nonwoven-needled
m-Vs-m
3.0 x
1.2 x
3.0 x
2.0 x
10-9
10-8
10-8
10-6
ft3/min-ft
2.0 x
8.1 x
2.0 x
1.3 x
10-6
ID'6
10-6
10-3
Permeability coefficient
cm/s
0.0006
0.002
0.004
0.04
ft/mi n
0.0012
0.0039
0.0079
0.079
aValues taken at applied normal pressure of 40 kPa (830 psf).
Source: Gerry and Raymond, 1983.
5.5.3.2 Hydraulic Transmissivity of Geonets Under Different
Boundary Conditions—
Limited results of testing a solid rib and a foamed rib geonet using
rigid plates above and below the nets are presented in Section 4.2.5.3. The
results of exploratory research on the effect of intrusion by FMLs into geo-
nets were also discussed. This subsection presents data from transmissivity
tests in which geonets were compressed between different types of surfaces to
5-141
-------
,.4
3 60
> 45-
NORMAL STRESS (kP«)
Mass Per Unn Area
Nominal Thickness
Polvmer
Geotextile
A
B
C
D
E
F
G
oz/ydz
16
18
18
16
12
14
16
g/cnv
540
600
600
540
400
470
540
Mils
210
190
150
160
110
130
110
mm
5.3
4.7
3.8
4.1
2.8
3.3
2.8
Type
PET
PET
PP
PP
PP
PP
PET
Filament
continuous
staple
continuous
continuous
continuous
staple
continuous
FIG. 2—Transmissiviiy response versus applied normal stress for various needled nontvoven geotexnles.
after Koemer and Bove 15].
Figure 5-41. Transmissivity response versus applied normal stress for
various needled nonwoven geotextiles. (Source: Koerner and
Bove, 1983, p 37).
simulate various in-service conditions (Williams et al, 1984; Koerner, 1988).
The variables in these tests included:
- Type of geonet.
- Number of layers of geonet.
- Type of surface and support of surface contrasting top and bottom of
geonet.
- Hydraulic gradient.
- Compressive stress.
5-142
-------
In the tests reported by Williams et al (1984), three types of geonets were
tested. One geonet was tested in a single, double, and triple layer con-
figuration. Testing was performed with various boundary conditions so that
the geonet was contacted by either a steel plate or a clay covered by a geo-
textile or a 20-mil PVC FML. Complete results are presented in Figure 5-42.
Uilliams et al (1988) observed the following:
- The hydraulic transmissivities of the tested geonets tended to
decrease with increasing hydraulic gradient (which indicates transient
or turbulent flow) and with increasing normal stresses.
- The effect of normal stress varied with the type of geonet (Tests 1,
4, and 5).
-Under the steel-piate-facing-steel-plate test conditions (Tests
1, 2, and 3), the hydraulic transmissivities of multiple layers of
geonets were approximately additive.
- The geotextiles in contact with geonets reduced the hydraulic trans-
missivity of the nets due to intrusion of the geotextile into the
channels of the net. The needle-punched geotextile intruded more than
the heat-bonded geotextile (Tests 8 and 9).
- The 20-mil PVC in contact with a geonet reduced the hydraulic trans-
mi ssivity of the geonet (Test 10).
Koerner (1988) measured the hydraulic transmissivity of a 0.25-in.
thick geonet under two different boundary conditions. The first profile
simulated the service conditions of a geonet in an FML-only top liner design,
and the second profile simulated the service conditions of a geonet in a
design containing an FML-soil composite liner as the top liner. These tests
were performed (1) to determine whether the clay particles would extrude
through the geotextile voids and (2) to determine whether the intrusion of
the geotextile into the geonet via the overlying clay would significantly
affect the drainage capacity of the geonet. The FML used in these tests was
a 60-mil HOPE, and the geotextile was a needlepunched, nonwoven polyester,
continuous filament fabric of 16 oz yd~2 mass per unit area. The load was
applied for 15 minutes, and flow was measured over the subsequent 15 minutes.
The results of these tests are presented graphically in Figure 5-43. These
results show the effect of hydraulic gradient and applied normal pressure on
flow rate. In addition, flow rates through the HDPE-geonet-geotextile-clay
cross section were 20-40% less than the flow rates through the HDPE-geonet-
HDPE cross section, indicating that intrusion of the geotextile into the
geonet did occur. The flow response curves and the cleanliness of the geonet
test specimens after disassembly indicated, however, that flow was not
blocked by.extrusion of the clay through the geotextile voids.
It should be noted that these results are based on short-term tests
using water to measure flow rates. The effect of creep on the flow rates of
5-143
-------
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CM
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c
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o o
~ IQ
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(
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Testl One Layer DN2
8
* A
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lydraulic Gradient (i
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ydraulic Gradient (i) Hydraulic Gradient (i)
t No. Lower Boundary Upper Boundary
1-5 Steel plate
6 Steel plate
7 Steel plate
8 Clay/heatbonded geotext
9 Clay/needlepunched geot
10 Clay/unreinforced geome
1
\ Geotextiles used as boundary layers:
Steel plate
Heatbonded geotextile/clay
Needlepunched geotextile/clay
lie Heatbonded Geotextile/clay
extlle Needlepunched geotextile/clay
mbrane Unreinforced geomembrane/clay
Normal Stress
(i) Heatbonded nonwoven polypropylene with a mass kPa (psf)
per unit area of 140 g/m2 (4 oz/sq yd);
• 10 200
11) Needlepunched nonwoven polypropylene, with a o 50 1,000
mass per unit area of 400 g/m2 (12 oz/sq yd). A 100 2,000
A 200 4,000
Geomembrane used as a boundary layer: • 350 7,000
Unreinforced 0.5-mm (20-mi ) thick
PVC. 0 500 10,000
Figure 5-42.
Results of transmissivity tests at 20°C on nets DN1, DN2, and
DNS performed under a range of normal stresses with various
boundary conditions. (Source: Williams et al, 1984, p 402).
5-144
-------
8
7
C 6
1 5
4
ca
en
co
CC
5000 10000
Normal Stress, Ib/ft2
(a) HDPE-Geonet-HDPE Cross Section
15000
03
ra
CE
I
Q (b), i-1.0
o (b),i»0.5
5000 10000
Normal Stress, Ib/ft2
j
15000
(b) HDPE-Geonet-Geotextile-Clay Cross Section
Figure 5-43. In-plane flow rate tests of a 0.25-in. thick geonet under
different boundary conditions. (Source: Koerner, 1988).
5-145
-------
these trial cross sections needs to be investigated. For example, a geo-
textile serving as a filter between a geonet and an overlying soil liner
could creep due to triaxial stresses potentially resulting in further in-
trusion into the geonet or opening of the voids which would allow extrusion
of the clay into the drainage system. In addition, the effect of organic
waste constituents being absorbed by synthetic drainage materials on the
short-term and long-term drainage properties of cross sections containing
these materials needs to be investigated.
5.6 BIODEGRADATION AND OTHER BIOLOGICAL STRESSES
In-service FMLs and other materials used in the construction of on-land
containment units for the storage or disposal of hazardous and toxic wastes
or materials contact soil and liquid, which are biological in nature. Over-
all, relatively few data have been obtained either in the laboratory or
from the field to show that biological factors have contributed to failure or
have had adverse effects on the performance of FMLs. It is recognized,
however, that FMLs are relatively new and have been in service for only a few
decades. There is concern regarding the service life of FMLs in these
environments over extended time periods.
The biological effects on FMLs that have been observed are:
- Loss of monomeric plasticizer from buried polymeric FMLs through
biodegradation. The polymer content in these FMLs have not exhibited
such degradation. The effect on the total composition, e.g. if it is
PVC, is embrittlement.
- Variations in the biodegradability of different plasticizers and
compounding oils.
- The adherence of fungi to some FMLs which probably reflects the
presence of particles and chemically active groups on the surface of
the FML. However, the effect does not penetrate the thickness of the
FML.
Burial tests, such as the burial test in ASTM D3083 which is appropriate
for testing natural and some synthetic fabrics, e.g. rayon and coated natural
fabrics, have been performed on synthetic polymers and polymeric products and
synthetic fabrics, but the exposure times (30 days) are far too short to
cause degradation of these materials. Long-term exposure (e.g. years) are
generally needed for assessing the biodegradability of synthetic polymers
such as those used in geosynthetics and pipe.
Early in the EPA waste disposal program there was concern regarding
the biodegradability of plastics and rubber products that would be placed in
landfills. Such products as tires and polyethylene wastes were recognized as
being particularly resistant to degradation in landfills (Gutfreund, 1971).
A number of research programs in the USA and Europe were initiated to in-
vestigate methods of degrading polyethylenes by biological means. Albertsson
5-146
-------
(1978a,b) observed that, with specially prepared unprotected HOPE containing
trace amounts of carbon-14, a small amount of microbial conversion of the
14C in the polyethylene to 14C02 took place. The HOPE had a 0.958 density,
contained no antioxidant or carbon black and was either made into thin films
of 0.8-mil thickness or pulverized to maximize surface area. Other research-
ers (Colin et al, 1976; Potts, 1978) have found that only the low molecular
weight fractions are metabolized by microbial action.
Data on long-term burial of commercial HOPE FMLs are not available.
Colin et al (1986) exposed commercial nonwoven getextiles to accelerated
soil-burial for up to 7 years and examined the recovered samples by burst
strength testing, optical microscopy, and infrared spectroscopy. The
specimens were based on polypropylene, polyethylene terephthalate (PET), and
a mixture of polypropylene and bicomponent fibers (nylon-coated polypropyl-
ene). None of the samples showed a significant decrease in strength outside
the experimental error.
Note: The subject of the longevity of FMLs and other polymeric
construction materials in service in waste containment
units is discussed more fully in Chapter 4.
5.7 ACCELERATED AGING AND WEATHERING TESTS
FML liners in service in many surface impoundments, including water
reservoirs and cooling and wastewater ponds, are not covered with soil.
They are thus exposed to the weather, that is, to the ultraviolet and in-
frared radiation of sunlight, oxygen, ozone, temperature variation, wind and
wave action, and rain. Considerable information has been accumulated over
the years on the weathering characteristics of polymeric compositions (Davis
and Sims, 1983; Hawkins, 1972). Considerable data have also been accumulated
on the weathering of some plastic and rubber FMLs in service (Strong, 1980).
The effects of weathering can take extended time for trends to develop;
consequently, accelerated test methods that correlate with actual service are
needed. Clark (1971) discusses artificial weathering devices and their
correlation with weather exposure.
In this section the comparative results of roof exposure of eight FMLs
for 3.37 years and accelerated outdoor exposure of ten FMLs are reported
and discussed.
5.7.1 Roof Exposure Tests
To determine the effect of weathering on FMLs, such as would occur on
the slopes of an uncovered surface impoundment, Haxo et al (1985b) exposed
6 x 6-in. specimens of 11 different polymeric FMLs on a rack placed on
Matrecon's laboratory roof in Oakland, California, at a 45° angle to the
south. Three specimens of each FML were hung on boards so that only one side
was exposed to the sun. The rack with the test specimens is shown in Figure
5-147
-------
5-44. The specimens were hung loosely to allow them to change dimensions
freely. These 11 FMLs were based on the following polymers:
- Butyl rubber (fabric-reinforced) (31 mil).
- CPE (30 mil).
- CSPE (nylon-reinforced) (30 mil).
- ELPO (20 mil).
- EPDM (2 FMLs) (30 and 62.5 mils).
- Neoprene (2 FMLs) (31 and 62.5 mils).
- Polyester elastomer (7 mil).
- PVC (2 FMLs) (20 mil).
Figure 5-44. Rack loaded for exposing FML specimens. The rack was exposed
at a 45° angle to the south. (Source: Haxo et al, 1985b, p
154).
One specimen of each of the FMLs was removed after 343, 745, and
1231 days of exposure, and the following properties were determined:
- Weight.
- Dimensions.
5-148
-------
- Volatiles, in accordance with Matrecon Test Method 1 (Appendix 6).
- Extractables, in accordance with Matrecon Test Method 2 (Appendix E).
- Tensile properties, in accordance with ASTM D412/D638, using a special
dumbbell which has the same width as that of the ASTM D412 Die C/
ASTM D638 Type IV dumbbell but which has a shorter overall length, a
shorter narrow section, and smaller tab ends. Two specimens were
tested in each direction. (Note: At the time this work was performed,
it was desired that all FMLs be tested in accordance with the same
test procedure; thus, fabric-reinforced FMLs were tested with dumb-
bell-type specimens. The preferred test specimen for testing limited-
size fabric-reinforced FML sample is a 1-in. strip specimen in accord-
ance with ASTM D751, Method B.)
- Tear strength, in accordance with ASTM D624 using Die C specimen
(unreinforced FMLs only). Two specimens were tested per direction.
- Hardness, in accordance with ASTM D2240.
Changes in surface characteristics, including cracking and checking, were
also observed.
Changes in the properties of the FML samples after 1231 days of exposure
are presented in Tables 5-63 and 5-64. The results are comparative as the
samples were all subjected to the same exposure. The results indicate some
of the differences in the weatherability of different polymeric FMLs. Some
of the major effects of the exposure were:
- With only a few exceptions, the specimens lost weight and extract-
ables content; the largest losses were sustained by the two PVC FMLs
which lost plasticizer. The CSPE increased in weight and volatiles,
perhaps due to moisture absorption, but appeared to lose in extract-
ables. The polyester elastomer FML lost significantly in weight and,
at the same time, increased in extractables content which may indicate
some degradation of the polymer.
- The moduli (i.e. stresses at 100 and 200% elongation) of all the FMLs
increased. The amount and mechanism of increase varied with the
individual FML. The CSPE and PVC FMLs increased the most, and one
EPDM, the ELPO, and the polyester FMLs increased the least. The
increase 1n modulus by the CSPE FML was the result of crosslinking
which took place during the exposure period; on the other hand,
the increases in the moduli of the PVC FMLs were due to loss of
plasticizer.
- All FMLs, except for the butyl rubber, lost in elongation. The butyl
FML was reinforced with a fabric which controlled the elongation at
break. The CSPE and neoprene FMLs sustained the greatest losses. The
decrease in the elongation of the CSPE FML was due to crosslinking.
5-149
-------
TABLE 5-63. EFFECT OF EXPOSURE ON ROOF OF LABORATORY IN OAKLAND,
CALIFORNIA, ON PROPERTIES OF POLYMERIC FMLS
Butyl, CPE, CSPE, ELPO, and EPDM
Polymer
Compound type3
Fabric type
Thread count, epib
Nominal thickness, mil
FML numberc
Analytical properties
Volatilesd, %
Extractablese, %
Solvent^
Dimensional properties
Weight, % change
Area, % change
Physical properties9
Tensile at fabric break, ppi
Percent retention
Tensile at ultimate break, psi
Percent retention
Elongation at ultimate break, %
Percent retention
Stress at 100% elongation, psi
Percent retention
Stress at 200% elongation, psi
Percent retention
Tear strength, Ib
Percent retention
Hardness, durometer points
Change in points
Exposure
time, d
0
1231
0
1231
...
1231
1231
0
1231
0
1231
0
1231
0
1231
0
1231
0
1231
0
1231
Butyl
XL
Nylon
20 x 10
31.3
57R
0.29
0.30
6.36
5.71
MEK
-3.32
-1.29
72.7
116
h
...
42
102
• • •
...
...
...
• * «
71A
-2A
CPE
TP
• • •
*30
77
0.14
0.33
9.13
6.32
n-neptane
-3.15
-7.33
• • •
...
2198
97
403
81
900
139
1180
135
7.38
116
80A
+4A
CSPE
TP
Nylon
8x8
30
6R
0.51
2.57
3.77
3.32
acetone
1.80
-6.04
35.9
138
56. 11
172
243
52
30. 51'
265
50.41
...
...
• • •
77A
-3A
ELPO
CX
» • *
• * •
20
36
0.15
0.06
5.50
5.33
MEK
-1.93
-1.38
• • •
• • •
2620
96
665
95
932
119
1018
116
8.56
98
32D
+60
EPDM
XL
• • •
• • •
62.5
8
0.38
0.45
23.41
21.31
MEK
-3.91
-3.25
• • •
...
1593
113
510
91
335
142
770
131
12.75
96
58A
+7A
EPDM
XL
• • •
*30
26
0.50
0.62
22.96
21.75
MEK
-3.11
-2.87
• • •
• # •
1900
108
450
94
358
119
878
121
7.40
87
58A
+3A
aXL = crosslinked; TP = thermoplastic; CX = semicrystalline thermoplastic.
bepi = Ends per inch. Data are for machine and transverse directions, respectively.
cMatrecon identification number; R = fabric-reinforced.
dDetermined in accordance with Matrecon Test Method 1 (see Appendix G).
determined in accordance with Matrecon Test Method 2 (see Appendix E).
^MEK - methyl ethyl ketone.
QValues for tensile properties and tear resistance are averaged for machine and transverse
directions.
nBulk of FML's strength is in the nylon fabric. The butyl coating over the fabric tended not fail
catastrophically, and no useful value could be obtained for tensile at ultimate break.
iReported value is in ppi.
Source: Haxo et al, 1985b, pp 243-45.
5-150
-------
TABLE 5-64. EFFECT OF EXPOSURE ON ROOF OF LABORATORY IN OAKLAND,
CALIFORNIA, ON PROPERTIES OF POLYMERIC FMLS
Neoprene, Polyester Elastomer, and PVC
Polymer
Compound type9
Nominal thickness, mil
FML number^
Analytical properties
Volatile*0, %
Extractablesd, %
Solvent6
Dimensional properties
Weight, % change
Area, % change
Physical propertiesf
Tensile at ultimate break, psi
Percent retention
Elongation at ultimate break, %
Percent retention
Stress at 100% elongation, psi
Percent retention
Stress at 200% elongation, psi
Percent retention
Tear strength, Ib
Percent retention
Hardness, durometer points
Change in points
Exposure
time, d
0
1231
0
1231
1231
1231
0
1231
0
1231
0
1231
0
1231
0
1231
0
1231
Neoprene
XL
31.3
43
0.45
1.03
13.69
9.93
acetone
-3.11
-3.86
1785
88
320
63
460
184
1038
149
5.41
86
57A
+14A
Neoprene Polyester
XL CX
62.5 7
82 75
0.19
0.76
13.43
11.45
acetone
-1.31
-2.31
1755
92
400
63
383
188
790
168
11.13
82
57A
+12A
0.26
2.74
0.13
3.92
MEK
-6.23
-1.42
6768
70
575
83
2585
110
2733
107
5.92
103
45D
+70
PVC
TP
30
11
0.15
0.42
33.90
26.27
CC1 4+CHaOH
-15.61
-10.28
2878
97
357
77
1420
161
2013
128
11.20
134
290
+180
PVC
TP
30
59
0.31
0.13
35.86
27.78
CC14+CH30H
-10.31
-10.75
2558
111
375
86
995
185
1580
145
9.89
144
26D
+130
aXL = crosslinked; CX = semi crystal line thermoplastic; TP = thermoplastic.
^Matrecon identification number.
C0etermined in accordance with Matrecon Test Method 1 (see Appendix G).
''Determined in accordance with Matrecon Test Method 2 (see Appendix E).
eMEK • methyl ethyl ketone; CC14+CH30H = 2:1 blend of carbon tetrachloride and methyl alcohol.
^Values for tensile properties and tear resistance are averaged for machine and transverse
directions.
Source: Haxo et al, 1985b, pp 246-47.
5-151
-------
5.7.2 EMMAQUA Testing
As part of a test program to assess the durability of FML field seams
in various environmental conditions that simulated over a short period (i.e.
52 weeks or less) conditions that FMLs may encounter in service, seam samples
were exposed for 1 year in the accelerated outdoor exposure test, EMMAQUA,
(Equatorial Mount with Mirror for Acceleration with Water Spray) (Morrison
and Parkhill, 1987). This accelerated exposure test is described and dis-
cussed in Section 4.2.2.5.4, and in ASTM D4364 and G90. During this period
of time, 32 representative seam samples were exposed to an accumulated total
solar radiation energy of 1.45 million langleys (cal cnr2), i.e. 60,648 MJ/m2.
This level of exposure is reportedly equivalent to approximately 8 years of
conventional outdoor exposure at the latitude of Phoenix, Arizona, where the
exposure test was run. At 6 months in the EMMAQUA test, by which time the
samples had been exposed to 660,430 langleys (27,632 MJ/m2), and at the
completion of the exposure, the samples were inspected and rated on a scale
of 1 (extremely poor condition) to 10 (as-received condition) for the fol-
lowing:
- General appearance.
- Del ami nation of seam.
- Checking/crazing.
- Blistering.
- Warping.
Results of the visual inspections are summarized in Table 5-65. At the end
of exposure the peel strengths of the samples were determined; retention of
peel strength averaged approximately 70-80% of the values of the unexposed
samples.
The results of the exposure indicated that the 1-year EMMAQUA exposure
period may be too long. Exposure under the accelerated weathering conditions
was too severe for some materials, thus producing results that may not
reflect exposure to natural weathering. For example, several polyethylene
samples suffered severe thermal degradation. Morrison and Parkhill (1987)
reported that their organization, U.S. Bureau of Reclamation, has routinely
conducted outdoor exposure tests on FMLs and never observed this type of
degradation. The 80-mil HOPE extrusion lap-welded field seam, Sample
No. 32, had melted enough to prevent testing of the seam; the LLDPE field
seam, Sample No. 34, contained two areas where the material appeared to have
melted. The thermal degradation appeared to have occurred between 6 and 12
months of exposure. Consequently, further studies are recommended to deter-
mine if the EMMAQUA exposure is truly representative of the long-term natural
weathering of FMLs. It should be noted that consideration is being given to
requiring FMLs, intended for exposure to natural weathering (as in surface
impoundments), and factory seams of these materials to pass a weathering
test (EMMAQUA exposure) of a minimum of 1,000,000 langleys with a rating
of 7 or better on a scale of one for extremely poor condition to 10 for
5-152
-------
TABLE 5-65. RATINGS IN VISUAL INSPECTIONS OF SELECTED SAMPLES EXPOSED TO EMMAQUA CONDITIONS
OJ
Sample
number
1
5
9
10
11
13
14
16
30
32
General
appearance
FML&
36-mil CPE(R)
36-mil CSPE(R)
38-rail EIA(R)
30-mil EPDM(R)
30-mil CPE
30-mil LLDPE
30-mil PVC
30-mil PVC/
CPE
30-mil HOPE
80-mil HOPE
6 mos.
8
9
9
9
8
7
8
8
8
8
12 mos.
6
8
8
9
7
4
7
7
7
5
Del ami nation
of seam
6 mos.
9
10
10
10
10
10
10
10
8
10
12 mos.
8
10
10
10
10
10
10
10
8
10
Checking/
crazing
6 mos.
10
10
10
10
10
10
9
10
10
10
12 mos.
10
10
10
10
9
7
7
10
10
9
Cracking
6 mos.
10
10
10
10
10
9
10
10
10
10
12 mos.
10
10
10
10
10
6
10
10
10
10
Blistering
6 mos.
9
10
10
10
10
10
10
10
10
10
12 mos.
7
10
10
10
10
10
10
10
10
10
Warping
6 mos.
8
9
9
9
8
8
8
8
8
8
12 mos.
7
8
8
9
7
4
7
6
5
8
Remarks
Some blisters inside seam
area at 6 months.
...
Sample was stiff.
...
...
At 12 months sample con-
tained two places where
it appears to have
melted.
...
Sample was stiff.
Sample was brittle.
Sample was very brit-
tle and contained large
area which appears to
have melted.
aKey to rating system: 10 as received; 9 excellent; 8 good; 7 good to fair; 6 fair; 5 fair to poor; 4 poor; 3 poor to very poor; 2 very poor;
1 extremely poor.
t>R « fabric-reinforced.
Source: Morrison and Parkhill, 1987, pp 78-80.
-------
"as-received" condition. A rating of 7 or better means that there are no
checks greater than 0.006 in. in width in the exposed sample when bent around
a 0.5-in. diameter mandrel. Under the EMMAQUA exposure, the total solar
radiation energy of 1,000,000 langleys can be achieved in approximately 8
months.
5.8 COMPATIBILITY TESTING OF FMLS IN ACTUAL WASTE
CONTAINMENT UNITS
An effective way of assessing the compatibility of an FML with the waste
which it may be used to contain is to place a sample of the FML in the pond
or drainage system of a containment unit containing the same type of waste
liquid or leachate. If the proposed unit is a surface impoundment, mounting
large samples of the candidate FML on racks and placing the racks on the
slope of the existing impoundment, which contains waste liquids of the type
to be impounded, would yield exposure conditions similar to those of a liner
in actual service. Placing the racks on the north slope with part of the
samples in the waste liquid and part in the air would also allow a section of
the samples to be exposed at the interface. Such an exposure would assess
the effects of "real world" exposure and the accumulated effects of many
months of variable conditions due to weathering and changes in the compo-
sition of the waste liquid. The results of a one-year coupon exposure
test, which was performed by Matrecon for a client, showed substantially
more severe effects than a four-month EPA Method 9090-type immersion test
performed in the laboratory with a "representative" sample of the wastewater;
however, the results of comparing the different FMLs yielded the same choice
of FML to use in lining a proposed pond.
Tratnyek et al (1984) described a methodology for exposing removable
coupons under various conditions, including compatibility tests and monitor-
ing the conditions of an FML and other materials of construction during
actual service in a facility.
5.9 SIMULATED EXPOSURE TESTING OF ADMIXED LINER MATERIALS
As part of the two simulated service research programs discussed
in Sections 5.4.1.1 and 5.4.1.2, asphalt concrete and soil cement samples
were exposed to MSW leachate and various hazardous wastes. The results of
these tests are discussed in the following subsections. It should be noted
that these research programs were intended to determine chemical compati-
bility and thus tested only limited-size samples. Potential mechanical
problems, such as a tendency to crack or brittleness, were not assessed.
5.9.1 Exposure to MSW Leachate
Haxo et al (1982) exposed 22-in. diameter samples of two types of
asphalt concrete and a soil cement to MSW leachate for up to 56 months in
landfill simulators. The simulator design in presented schematically in
Figure 5-11. An analysis of the leachate generated by the simulators is
presented in Table 5-7. The two types of asphalt concretes tested included a
paving asphalt concrete and a hydraulic asphalt concrete. The paving asphalt
concrete contained 7.1 parts of asphalt (60-70 penetration grade) per 100
5-154
-------
parts of aggregate. The aggregate was Watsonville granite proportioned to
meet the 0.25-in. maximum gradation for dense-graded asphalt. The original
voids ratio was 6.4%. Specimen thickness was 2.2 inches. The hydraulic
asphalt concrete contained 9.0 parts of asphalt (60-70 penetration grade)
per 100 parts of the same aggregate used to make the paving concrete. The
original voids ratio was 2.9%. Specimen thickness was 2.4 inches. Soil from
the Radum quarry near Pleasanton, California, was used with Type 5 (sulfate-
resistant) portland cement for preparing the soil cement. Since the fines
content of the Radum soil was lower than optimum for soil cement, a few
percent of nonswelling clay (kaolin) was added. The soil cement specimens
were 4.5 in. in thickness and were made of 95 parts of soil, 5 parts of
kaolinite clay, 10 parts of portland cement, and 8.5 parts of water.
One of the asphalt concrete liners developed a leak which was probably
related to inadequate compaction at the center of the specimen where the leak
occurred. This result indicates that thicker asphalt concrete liners or
double lifts are needed to prevent leakage. The 2 to 4-in. specimen design
thickness was selected for the research program to accelerate the test
conditions. Both asphalt concretes lost considerably in unconfined compres-
sive strength, as is shown in Table 5-66. These losses were greater than
were anticipated from the 24-h water immersion at 60°C and were probably the
result of absorption of water and dissolved organics which took place over
the prolonged exposure and stripping of asphalt from the aggregate. The
asphalt extracted from the concretes hardened, though it did not harden as
much as asphalt extracted from a sample exposed to weather and air. This
result probably reflects the anaerobic environment at the bottom of the
simulators.
TABLE 5-66. UNCONFINED COMPRESSIVE STRENGTH OF ADMIXED LINER
SPECIMENS BEFORE AND AFTER EXPOSURE TO WATER AND TO MSW LEACHATE
Paving
asphalt
concrete
Exposure
Original strength,
psi
Water soak for
24 h at 60°C
In simulators for
12 months
In simulators for
56 months
psi
2805
2230
423
258
%
100
80
15
9
Hydraul ic
asphalt
concrete
psi
2715
2328
349
172
%
100
86
13
6
Soil
cement
psi
19109
13239. b
1188
1182
%
100
69b
62
62
aMeasured on specimen molded in accordance with ASTM D558.
bWater soak at room temperature.
Source: Haxo et al, 1982, p 61.
5-155
-------
The soil-cement liners lost some of their compressive strength (Table
5-66) and hardened considerably during exposure. Whereas satisfactory cores
could not be cut from the unexposed soil cement, the exposed liners could be
cored like a Portland cement, indicating continuation of cure during exposure.
The results of the permeability testing, which are presented in Table 5-67,
indicate that the soil cement had possibly become less permeable during
exposure. However, these results may be related to variations in compaction.
A small leak developed in the second liner after approximately 1 year of
exposure.
TABLE 5-67. PERMEABILITY OF SOIL-CEMENT SAMPLES
BEFORE AND AFTER EXPOSURE TO MSW LEACHATE
Property Soil cement3
Density, g mL'1 2.169 (dry)b
Density, Ib ft'3 135.4 (dry)b
Coefficient of permeability0, cm s~l
Unexposed 1.5 x 10~6b
After 12 months of exposure 1.5 x 10~8 (T)
4.0 x 10~7 (B)
After 56 months of exposure:
Area in which leak detected ^'7 x 10~5 (B)
4 3 x 10~7 (T)
Area in which no leak detected j'2 x JQ-S
aT = top; B = bottom.
^Measured on a specimen molded in accordance with ASTM
D588.
cDetermined in a back-pressure permeameter (Vallerga
and Hicks, 1968).
Source: Haxo et al , 1982, pp 148-49.
5.9.2 Exposure to Hazardous Wastes
Haxo et al (1985b) exposed hydraulic asphalt concrete and soil cement
samples to various hazardous wastes. The combination of wastes and admixed
liners tha't were tested included the following:
5-156
-------
Waste identification
Combinations tested
Type
Acidic waste
Akaline waste
Lead waste
Oily waste
Name
"HN03-HF-HOAc"
"Spent Caustic"
• • •
"Slurry Oil"
"Oil Pond 104"
Hydraulic
asphalt concrete
X
X
X
• • •
• • •
Soil cement
• • •
X
X
X
X
Pesticide
"Weed Killer"
Two cells were tested for each liner-waste combination. Analyses of the
wastes are summarized in Appendix J. The cell used to expose the liner
samples is presented schematically in Figure 5-45.
• Top Cover
Epoxy
Coated •
Bolt-
Flanged Steel'
Spacer
Neoprene Sponge Gaiket
WASTE
Waste Column:
. 11 Gauge Steel
10"x15"x 12" High
w/Welded 2" Flange
Epoxy Grout Ring
ADMIX LINER
Screen
Figure 5-45. Design of cells for long-term exposure of admix liners to
different hazardous wastes. The area of the liner specimen in
contact with the wastes measured 10 x 15 inches. (Source: Haxo
et al, 1985b, p 76).
The hydraulic asphalt concrete mix included dense-graded aggregate to
0.25-in. maximum size and 9 parts of asphalt AR-4000 per 100 aggregate. The
5-157
-------
water permeability of six cores taken from unexposed samples ranged from 2.8
x 10~° to 1.7 x 10~9 cm s~l. Liner thickness was 2.5 inches. The soil
cement was a compacted mixture of 12 parts of Type 5 (sulfate-resistant)
Portland cement, 13.4 parts of water, and 100 parts of a "waste fines" from
a local quarry. Permeability of a core taken from an unexposed liner was
5.7 x 10"° cm s~l. Liner thickness was approximately 4 inches.
In spite of the low permeability and good mechanical properties of the
asphalt concrete, the asphalt concrete liners were deficient in several
exposures. Both specimens in contact with the strong acid ("HN03-HF-HOAc")
developed leaks; some of the aggregate at the surface was dissolved, and the
asphalt itself hardened severely during exposures that were relatively short
(40 and 199 days). Leaks also developed in the specimens below the "Spent
Caustic" and lead wastes. The lead waste contained sufficient oily con-
stituents to cause the asphalt concrete to become almost a slush. Some
seepage also occurred through the specimens. Combinations of the asphalt
concrete and the oily wastes were eliminated in the screening tests. Results
also indicated that a thickness of 2.5 in. may be insufficient even for water
and compatible dilute wastes.
The soil-cement specimens showed good resistance to "Spent Caustic," the
lead waste, the two oily wastes, and the pesticide waste. Soil-cement had
been eliminated from exposure to the strong acid waste ("HN03-HF-HOAc") in
the screening tests. No seepage occurred in any of the specimens. In the
five specimens recovered and tested, actual increases in compressive strength
occurred. It must be recognized that these specimens were all small and not
subject to shrinkage or cracking that would be experienced in large instal-
lations.
5.10 SIMULATED EXPOSURE TESTING OF SPRAYED-ON FMLS
As part of the two simulated service research programs discussed in
Sections 5.4.1.1 and 5.4.1.2, limited testing of sprayed-on asphalt FMLs was
performed after exposure to MSW leachate and various hazardous wastes. The
results of these tests are discussed in the following subsections.
5.10.1 Exposure to MSW Leachate
Haxo et al (1982) exposed two types of asphaltic sprayed-on FMLs for
up to 56 months to MSW leachate in landfill simulators (Figures 5-11 and
5-12). An analysis of the leachate generated by the simulators is presented
in Table 5-7. The first type of sprayed-on FML was a catalytical ly-blown
asphalt that was cast in place at 425°F on a sand bed covering the aggregate
in the base of the simulator. The second type was an asbestos-filled anionic
asphaltic emulsion that had been sprayed on a nonwoven polypropylene fabric.
Both types of liners were approximately 0.30-in. thick.
The effect of the exposure on the asphalt in these FMLs is presented
in Table 5-68. However, it should be noted that to perform these tests, the
asphalt is heated and the volatile content removed. Consequently, these data
do not reflect the properties of the in-service asphaltic FML.
5-158
-------
TABLE 5-68. PROPERTIES OF ASPHALT IN SPRAYED-ON FMLS
AFTER 12, 43, AND 56 MONTHS OF EXPOSURE TO MSW LEACHATE
Type of asphalt
Catalytically-
Property blown Emulsified
Viscosity at 25°C in sliding plate
viscometer at shear rate of 0.05 sec~l;
Original, MP 8.5 4.5*
After 12 months, MP 10.4 2.9
After 43 months, MP 12.2 3.1
After 56 months, MP 17.4 3.1
Change from original, MP +8.9 -1.4
Penetration at 25°C at 100 g
and 5 seconds:
Original 36b 46a»b
After 12 months6 34 55
After 43 months6 31 53
After 56 months6 27 53
Change from original -9 +7
Softening point, °C:
Original 89 ...
After 12 months 89
After 56 months 101 ...
aAsphalt extracted from unexposed specimens stored 12 months.
bCalculated from viscosity data.
Source: Haxo et al, 1982, p 150.
The catalytically-blown asphalt sample exposed for 12 months appeared
little affected by the exposure. The sample exposed for 50 months had a
nonhomogeneous appearance. Some areas had become quite weak or "cheesy" and
cracked easily when bent while other areas remained tough and flexible.
Samples from two weak areas and one "normal" area were tested for volatiles
and viscosity. The weaker area had absorbed approximately three times as
many volatiles as the other two areas. All three areas had approximately the
same viscosity. The cheesy areas became less pronounced as the sample dried
out in storage.
As with the catalytically-blown asphalt, the FML based on an asphaltic
emulsion that had been sprayed on nonwoven fabric showed no deterioration
after one year of exposure to MSW leachate, even though analyses showed that
it contained 4.8% moisture. The asphalt extracted from this FML was lower in
viscosity after 12 months of exposure to leachate than before exposure. The
5-159
-------
viscosity at the low shear rate, 0.001 sec'1, was substantially unchanged,
indicating a lower shear susceptibility than for the unexposed specimen. At
56 months the asphalt emulsion liner continued to show no visible deterior-
ation. Analyses showed that this FML had absorbed additional leachate and
contained 8% leachate compared with the 4.8% after one year of exposure.
5.10.2 Exposure to Hazardous Waste
Haxo et al (1985b) exposed an emulsified asphalt that had been applied
on a nonwoven polypropylene fabric mat to three hazardous wastes, including a
pesticide, an alkaline, and a lead waste. Two cells were tested for each
FML-waste combination. Analyses of the wastes are presented in Appendix J.
The cell used to expose the samples is presented schematically in Figure
5-15. This type of FML was not tested with an acidic waste included in the
research program because it caused the asphalt to harden severely in a
preliminary exposure test, and it was not tested with the oily wastes because
of the high mutual solubility of the asphalt and such wastes. This FML
functioned satisfactorily with the pesticide and the alkaline wastes;
however, when the cell containing the lead waste was dismantled, the gravel
below the liner was wet and stained, indicating that some seepage had oc-
curred. The results of testing the FML samples and the extracted asphalt are
presented in Table 5-69. The volatiles content of the samples exposed to the
alkaline and lead wastes increased significantly.
5.11 REFERENCES
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5-160
-------
en
i—*
CT}
TABLE 5-69. EFFECT OF EXPOSURE TO HAZARDOUS WASTES
ON AN EMULSIFIED ASPHALT SPRAYED-ON NONWOVEN FABRIC^
Waste type
Waste name
Matrecon waste serial number
Alkaline
"Spent
Caustic"
(W-2)
Lead
• • •
(W-4)
Pesticide
"Weed
Killer"
(W-ll)
Exposure time, days None
Asphaltic liner:
Volatiles content of liner, % 0.26
Water vapor permeability^,
metric perm cm 6.7 x 1
671
1480
12.9 15.3
656
18.6
1348
21.5
487
1.45
Extracted asphalt:
Viscosity at 25°C, P x 10&
at 0.05 s-1
at 0.01 s'1
at 0.001 s"1
Shear susceptibility
PenetrationC at 25°C
6.1
5.9
5.7
-0.02
41
4.40
4.22
4.00
-0.02
47
8.14
8.03
7.72
-0.02
37
5.52
5.56
5.92
0.02
43
6.49
6.91
7.53
0.04
40
5.4
5.4
5.4
0.00
43
aLiner covered with 1.5 in. of silica sand on which the waste was placed. Analyses of wastes
are summarized in Appendix J.
&ASTM E96, Method BW.
cCalculated from viscosity at 0.05 s~l by formula of Carre and Laurent (1963):
(Pen)2'6 = 9.5 x 1010
Source: Haxo et al, 1985b, p 103.
-------
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Association International, St. Paul, MN. pp 175-180.
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Flexible Membrane Test Facility. REC-ERC-8C-9. U.S. Department of the
Interior, Denver, CO. 25 pp.
Frobel, R. K. 1983. A Microcomputer-Based Test Facility for Hydrostatic
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Koerner, R. M., and J. A. Bove. 1987. Lateral Drainage Designs Using
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Gutfreund, J. 1971. Feasibility Study of the Disposal of Polyethylene
Plastic Waste. SW-14C. U.S. Environmental Protection Agency. No. 2010
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Hawkins, W. L. 1972. Polymer Stabilization. Wiley-Interscience, NY.
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nati, OH. pp 130-158.
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Haxo, H. E. 1977. Compatibility of Liners with Leachate. In: Proceedings
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In: Proceedings of
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5-167
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CHAPTER 6
FMLS AND RELATED MATERIALS OF CONSTRUCTION
IN SERVICE ENVIRONMENTS
6.1 INTRODUCTION
As is discussed in Chapter 5, the bulk of available information related
to the compatibility of FMLs with various waste liquids and their durability
in service environments is based on laboratory or small-scale pilot tests.
Furthermore, in selecting a liner, the chemical compatibility of an FML with
the waste to be contained is determined by performing laboratory testing,
e.g. immersion tests performed in accordance with EPA Method 9090 (EPA,
1986). Although the EPA is developing expert systems to aid in selecting a
liner (Rossman and Haxo, 1985), these systems are largely based on laboratory
results combined with general knowledge of the liner materials and wastes and
liquids to be contained. The relationship between data generated in labora-
tory or small-scale pilot tests and field performance of FMLs in waste
containment units is still poorly defined because specific data on the
performance and durability of full-scale liner systems are limited.
Data based on laboratory and small-scale pilot studies suffer from
serious limitations when used to predict compatibility, service lives, and
durability of lining materials in actual full-scale service. Some of these
limitations include:
- Samples of liner materials tested in laboratory studies are very small
in size in comparison with the amount of material required for lining
a full-scale TSDF. In a laboratory there is no way to measure the
effect of variations (e.g. in ply adhesion, composition, etc.) in the
materials themselves on their ability to function in a service
envi ronment.
- Exposure conditions in a laboratory are highly controlled in contrast
to the variability of conditions in a field situation. In TSDFs,
waste liquids and leachates can be highly variable, varying in both
content and concentrations, and can also vary greatly with time
and with depth and location within a given containment unit. In
addition, the level and temperature of the waste and the exposure
temperature vary with time, particularly in surface impoundments.
- In contrast to field seaming operations, laboratory seams are prepared
carefully under controlled conditions. From laboratory studies, it is
not possible to know the effect of variations in seaming workmanship
6-1
-------
and seaming conditions on performance. However, it should be noted
that at present (1988) there are trends towards more automated seaming
equipment and a higher level of quality control and quality assurance.
- In contrast to FMLs in actual service, laboratory samples are not
exposed under overburden, nor are they generally exposed under strain
or stress.
In order to fully understand the performance and durability of liner
systems and their components under full-scale service conditions, detailed on
site observations and inspections need to be made, and data resulting from
testing samples of observed liners need to be obtained. Though much data on
FML performance in various field applications have been collected, these data
are proprietary and are not available in the open literature. In addition,
even though reports and papers over the past decade have presented the
results of field studies, most of these reports are not highly detailed. As
a consequence, the EPA undertook several on-site field verification studies
and surveys to collect detailed information on the performance of lining
materials in waste containment units.
This chapter discusses the objectives of field studies and the various
factors that may contribute to an increase in seepage through an installed
FML beyond design levels. This chapter also reviews selected field studies
of FML performance in different types of containment units and presents data
on exposed FMLs which can be related to FML exposures studied in laboratory
simulated-service environments. Two field studies of geotextiles and the
limited results of an investigation of granular leachate collection and re-
moval systems in MSW landfills and an interview survey to describe potential
failure mechanisms in such systems are reviewed.
6.2 OBJECTIVES OF FIELD STUDIES OF LINER SYSTEMS IN CONTAINMENT UNITS
As is discussed in Chapter 7, waste containment units are complex
structures involving many layers of different materials, each of which must
function properly if the unit is to meet its performance requirements. The
components of a closed double-lined landfill can include:
- Supporting structures (including the foundation and embankments).
- An underdrain system.
- A liner system comprised of:
--A bottom liner.
--A top liner.
--A leachate collection and removal system (LCRS) between the
two liners for detecting and removing liquids that have leaked
through the top liner.
6-2
-------
--An LCRS on top of the liner for controlling the leachate head
acting on the lining system.
- A cover system.
- A groundwater monitoring system.
Each component depends upon the other components to function properly; also,
the components interact with each other. For example, the competence of the
foundation and the embankments has to be maintained in order to support the
liner system, which in itself is not a structural component. An FML must
retain its integrity and not allow liquids to enter the foundation and the
embankments which could cause it to fail and which, in turn, could cause a
catastrophic failure of the liner.
Because polymeric materials have only been used in constructing waste
containment units for approximately 20 years, on-site field studies of the
performance of liner systems need to be conducted for the following reasons:
- To assess the performance of waste containment units, with particular
reference to the performance of the individual components.
- If a failure has occurred, to determine the cause of failure, in-
cluding determining the type of failure, the mechanism of the failure,
and the conditions that led to the failure. Such an investigation
would be similar to an autopsy.
Only by analyzing failure can knowledge develop regarding the limitations
of FMLs and the other materials used in constructing an FML-lined containment
unit. This information can be used to point out needs for improving resins,
FML manufacturing techniques, seaming techniques and other construction
practices, and the overall design requirements.
The function of a lining system for a waste containment unit is to
prevent the migration of liquids and the dissolved constituents that are
contained into the environment, particularly the groundwater. A lining
system is said to have failed once it can no longer meet the design require-
ment of controlling the migration of liquids and dissolved constituents so as
to protect human health and the environment. FMLs can fail in one of two
ways:
- An increase in the permeability of the liner to the contained liquids
and the dissolved constituents.
- A breach in the liner, which would allow free liquids to flow through
the liner.
An increase in the permeability of a liner could arise from chemical incom-
patibility of the FML to the contained waste liquid due to the swelling or
dissolution of the liner or its components. Evidence of this type of failure
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has been seen in laboratory testing. On the other hand, a breach in the
liner can arise from one of many causes, including seam failure, cracks in
the FML, tears, pinholes, etc. Some of these failures may might reflect
inherent weaknesses or defects in the FML or changes in the properties of the
FML resulting from exposure to the chemical environment; most, however,
appear to be caused by combinations of stress and various factors relating to
design and construction. Potential modes of FML failure and factors that
could contribute to failure are discussed in the next section.
Field studies of FML performance can be approached from the engineering
point of view and the materials point of view. In the materials approach,
the relationship between the analytical and mechanical properties of an FML
and its field performance in waste contaiment units is analyzed. Failures
need to be analyzed to determine whether or not the failure is related to
changes in the FML caused by exposure to the service environment (e.g. to
sunlight and weathering on a slope or to a waste on the floor of the unit).
These changes in the FML would be reflected by a change in the balance of the
FML's properties and/or a single property. Such a change in the FML can
result from changes in composition (e.g. swelling or extraction of plasti-
cizer), from degradation of the polymer (e.g. oxidation), or from long-term
responses resulting from simultaneous exposure to a variety of mechanical and
chemical stresses (e.g. the development of stress-cracks). Except in cases
where these changes result in a significant change in permeability, these
changes themselves will not result in failure but will result in changes in
the FML's balance of properties which make the FML more susceptible to
failure by mechanical stresses.
An important goal of the materials approach is to develop criteria for
predicting the long-term serviceability and the chemical compatibility of an
FML with a particular leachate or waste liquid based on the results of
laboratory testing. To develop such criteria, a correlation needs to be
established between measurable properties of an FML and the performance of
that FML in a specific environment. Given this correlation between pro-
perties and performance, the rate of change in the properties of an FML
exposed in a laboratory test could then be used to predict the service life
of that FML under well-defined service conditions. For example, if it were
demonstrated that a 50% loss of a certain property correlated with a high
degree of confidence with FML failure, then using the rate at which that
property changes in laboratory testing (which itself has been correlated with
the rate of change under service conditions) the approximate service life
could be predicted. In addition, given such a correlation, it will be easier
to improve and develop compounds and resins that will have improved charac-
teristics for long-term service in waste containment applications.
No such correlation for FMLs in service environments, however, has
been developed. First of all, only a limited amount of data is available in
the open literature regarding the effects of the service conditions on FMLs.
Because of the proprietary nature of waste containment operations and the
manufacture and installation of FMLs and because of the potential repercus-
sions resulting from open knowledge of a liner failure, almost no data are
available in the open literature regarding FML failures from strictly
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materials causes. In addition, it should be noted that different types of
polymeric compositions respond differently to exposure conditions and if they
degrade they can be subject to very different types of degradation. These
differences complicate the issue because a property (or balance of pro-
perties) that may correlate with performance for one type of FML may not
correlate with performance for another.
From a materials point of view, the ultimate goal of field studies
on FMLs is to develop a correlation between measurable properties and field
performance. However, to do this, field studies are needed for the following
reasons:
- To assess the field performance of in-service FMLs to determine
whether or not these materials can function adequately in service
environments. At the time the EPA initiated research on FMLs in the
early 1970's, there was concern about whether or not FMLs could
successfully control the migration of waste constituents from a
well-engineered containment unit.
- To assess the changes in properties that have occurred in the in-
service FML in order to assess the deterioration that may have
occurred.
- To determine what FML properties correlate with field performance. In
the chemical compatiblity testing performed to date, i.e. that de-
scribed in Section 5.4 and testing performed in accordance with
EPA Method 9090 (EPA, 1986), it has been assumed that measuring
changes in hardness, tensile properties, tear resistance, volatiles,
extractables, etc. will be correlatable with field performance.
However, if the FML is subject to degradation after long-term exposure
by stress-cracking, changes in the properties mentioned above will
probably not be directly correlatable with field performance.
- To determine what level of change in a property or a balance of
properties correlate with either the success or failure of an in-
service FML.
- To determine whether the responses of FMLs in field-simulated labora-
tory and small-scale pilot tests are similar to their responses in
service environments.
- To determine what service conditions affect the performance of an
FML, and in particular, to determine what chemical stresses are the
most aggressive.
In the engineering approach, it is assumed that FMLs can function
adequately in service environments. Thus, the performance of the FML is
assessed in terms of how it functioned as a component of engineered and
constructed systems. In the case of a failed FML, the design requirements,
construction practices, and management practices that may have contributed to
failure are analyzed. For example, the mechanical properties of a failed FML
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can be analyzed to determine whether they were sufficient for the mechanical
conditions resulting from construction, installation, and service and to
determine how those mechanical conditions could be changed so as to reduce
mechanical stresses on the FML. This information can be used to develop and
verify design equations for evaluating the required mechanical properties of
an FML under specific mechanical conditions, e.g. the ability of an FML to
support its own weight on the side slopes [see Richardson and Koerner
(1987)]. One example analyzing field experience from an engineering perspec-
tive is the variety of responses to field experience indicating that thin
FMLs (i.e. those $ 20 mils) which were being installed during the early
1970's were susceptible to puncture. Even though no single test method has
been correlated with the incidence of punctures in FMLs, engineers and FML
manufacturers responded to the field experience by:
- Changing the construction of the sheeting by increasing the thickness
and/or using fabric reinforcement. In addition, FMLs based on poly-
mers that result in sheetings with a higher puncture resistance have
also been introduced.
- Changing design requirements to decrease the localized stresses
caused by objects in contact with the FML, e.g. by including stricter
requirements for subgrade finishing and by requiring bedding layers or
geotextile protectors.
- Changing construction practices to reduce the incidence of puncture,
e.g. during the placement of the soil layer on top of an FML.
- Increasing the role of CQC and CQA inspection to ensure that the
design requirements are being met and that the recommended construc-
tion practices are being followed.
- Developing stricter management procedures for reducing the incidence
of puncture, e.g. by not allowing vehicles to travel directly on top
of an FML, etc.
Field studies from the engineering perspective are necessary to develop
better designs, construction practices, and management practices to reduce
mechanical stresses on an FML and thereby reduce the potential for failure
and to develop knowledge about what mechanical properties (e.g. strength,
friction angle against a soil) are required given a specific application.
6.3 POTENTIAL MODES FOR FML FAILURE AND CONTRIBUTING FACTORS
As was mentioned in the previous section, if an FML fails, failure will
occur in one of two ways:
- An increase in the permeability of the liner to the contained liquids
and dissolved constituents.
- A breach in the liner, which would allow free liquids to flow through
the liner.
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This section discusses these types of failures and then discusses the various
types of factors that could contribute to FML failure.
6.3.1 Types of FML Failures
6.3.1.1 Changes in the Permeability Characteristics of the FML--
A significant increase in the permeability of an FML to the liquids
and the dissolved constituents with which the FML is in contact could arise
due to chemical incompatibility after prolonged exposure. Evidence of this
type of failure was seen in a laboratory test in which a highly alkaline
waste was sealed inside a pouch fabricated from an ELPO FML. As is discussed
in Section 5.4.1.6.2, after approximately 1 year of test, the rate at which
water entered the pouch increased dramatically, indicating a change in the
permeability of the FML.
6.3.1.2 Mechanical Failure--
6.j. 1.2.1 Puncture--Breaches in FMLs can occur due to puncture by
impact of tools or sharp rocks falling, or by sharp angular rocks in the
subgrade that have become exposed because soil fines have migrated downward
over time, or because of inadequate subgrade preparation or selection
of cover materials. Puncture during operations, by man or vehicle, is of
concern but can largely be mitigated through good installation and operation
procedures. Burrowing animals can puncture FMLs below the surface and hoofed
animals seeking water can puncture exposed liners.
6.3.2.1.2 Tea_r--Tear damage is similar to puncture damage in its
occurrence and can be initiated by a puncture followed by stress at the hole.
Tear, like puncture, can occur due to operations or to animals. The propa-
gation of tears and punctures can result in catastrophic generation of
breaches.
6.3.1.2.3 Cracks—Cracks can develop when an FML is simultaneously
exposed to environmental stresses (e.g. ozone, sunlight, or a waste liquid)
and mechanical stresses. For example, cracks can develop in an FML exposed
on a berm and in exposed areas with folds. Cracking can also develop from
static stress and dynamic fatigue such as might occur with alternating
thermal expansion and contraction. As with punctures, these cracks can
initiate tears that can result in catastrophic failure.
6.3.1.2.4 Abrasion--The continuous or near continuous action of
abrasion caused by wind or wave action on an FML can have a significant
wearing effect over time. In arid regions, sand particles carried by the
wind have a sand blasting effect on the FML. Runoff entering the pond from
the surrounding topography may contain sticks, branches, rocks, and other
debris which could abrade, tear, or even puncture the FML. Allowing liquids
that are being placed in a unit to splash directly onto an FML during place-
ment can have the same effect.
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6.3.1.2.5 Seam failure—Factory and field seams can split open due
to inadequate adhesion and due to excessive stresses on the FML which
can arise from subsidence, wind and wave action, gas pressure underneath the
unit which has not been properly vented, shrinkage, hydrostatic pressure,
slope sloughing, and thermal expansion and contraction. Some seams can be
greatly weakened during service due to the absorption of organics by the
adhesive or entrance of organics into the interface between the sheets of FML
that were seamed.
6.3.2 Factors That Could Contribute to FML Failure
The occurrence of breaches in the liner may arise from defects in the
FML. However, by far the most prevalent breaches are likely to be the result
of a sequence of events, all of which contribute to the development of a
breach. For example, a breach in a seam on the slopes can develop because of
a sequence involving the materials, the slope of the unit sidewall, the
placement of the FML, the seaming workmanship, inadequate QA/QC, unusual
stresses on the seam which could pull the seam apart, and possibly chemical
effects due to incomplete fusion at the bond interface of the seam, or
softening of the FML. Another example would be the tearing of an FML on a
slope due to the sloughing of a protective soil cover. The sloughing could
be related to design of the sidewalls at too steep a slope, excessive
rainfall resulting in saturation of the soil, insufficient provision for
drainage through the soil, and an inadequate coefficient of friction between
the soil and the FML. Factors that could contribute to the development of
breaches in FMLs are listed in Table 6-1. Some of these factors are dis-
cussed in the following subsections.
6.3.2.1 Material Factors--
6.3.2.1.1 Chemical incompatibility--The durability and service life
of a given FML in a waste containment unit can depend to a great extent on
the specific liquids which contact the FML from the time it is installed
through the rest of its service life. For example, dissolved organic con-
stituents in a leachate, even in minor amounts, can be preferentially ab-
sorbed by organic liner materials and may, over extended periods of time,
result in significant swelling and softening of FMLs.
Two types of chemical incompatibility between an FML and a leachate
or a waste liquid include swelling of the FML and extraction of components of
the FML compound. Swelling is the absorption of constituents of a waste
liquid or leachate by an FML. Even though swelling generally does not
affect the molecular structure of an FML, it can soften the FML. Swelling
can potentially cause significant losses in strength, elongation, creep and
flow resistance, and puncture resistance. In some cases, there may also be
an increase in permeability. A severe situation exists at the top liquid
line of a surface impoundment where the FML can be subject to alternating
cycles of swelling and drying out. Data showing the tendency of FMLs to
absorb significant amounts of organics, even from dilute aqueous solutions,
are presented in Chapter 5.
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TABLE 6-1. POTENTIAL FACTORS THAT COULD CONTRIBUTE TO THE FORMATION OF
BREACHES IN AN FML IN SERVICE IN A WASTE CONTAINMENT UNIT
Type of factor
Factor
Material
Site
Design and engineering
Construction
Quality control/
quality assurance
Service environment
Operational practice
Defects in sheeting (e.g. holes, foreign
materials)
Sensitivity of the selected material to
the service environment (chemical in-
compatibility, inadequate UV resistance,
etc.
Environmental stress-cracking
Degradation of compound or polymer
Inadequate physical properties including
response to multiaxial strain
Creep
Dimensional instability (shrinkage)
Crazing, cracking
Inadequate seaming system
Subsidence
Gas formation caused by decomposition
of organic materials in soil
High water table (reverse hydrostatic
pressure)
Chemical reactivity of subsoil
(e.g. solubility in acids)
Improper selection of materials (FML, soil
for soil liner)
Inadequate specification of materials
Inadequate compatibility testing
Improper use of materials
Supporting structure problems
Stress fatigue and cracking
Inadequate protection against ice
Inadequate subgrade compaction
Inadequate subgrade finishing
Poor quality of seams (e.g. holidays,
fish mouths, inadequate strength)
Inadequate anchoring
Inadequate sealing around structures
Inadequate inspection of construction,
allowing disregard of specifications
and poor construction quality
Inadequate inspection of materials
Attack by weathering, ozone
Chemical attack by constituents of the
waste
Attack by wind and wave action
Biological attack, including bio-
degradation
Attack by animals and insects
Inadequate maintenance of protective cover
Inadequate control of incoming wastes
Inadequate control of methods of placing
waste in unit
Inadequate maintenance of run-on manage-
ment systems
Improper cleaning procedures
Vandalism
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Contact with a liquid can also result in plasticizers being extracted
from the FML. FMLs, such as those based on PVC, which contain large amounts
of monomeric plasticizer(s), are highly susceptible to extraction and evapo-
ration of the plasticizer. Such loss of plasticizer can result in embrit-
tlement, shrinkage, and given excessive stress levels, breakage of the
FML. The use of higher molecular weight plasticizers does much to reduce
this effect.
Chemical incompatibility can also result in an increase in the perme-
ability of the FML. An increase during service is difficult to observe
and would be difficult to distinguish from small breaches. Through careful
monitoring it may be possible to observe such an increase in FML permeability
in an LCRS underneath the liner, perhaps as an increase in the concentrations
of organics permeating the FML. This would probably also show up by sampling
and measuring the swelling and changes in properties of the liner or coupon
exposed on the berm, in the sump, etc. The increase could also be demon-
strated by an increase in permeability by long-term laboratory testing.
Changes of this type have only been observed in a few cases in laboratory
testing, as is discussed in Chapter 5.
The effects of chemical stresses on FMLs are discussed in more detail
in Sections 5.3.1 and 5.4.
6.3.2.1.2 Creep—As is discussed in Section 4.2.1.5, creep describes
increasing deformation of a material under sustained load. The main factors
which influence creep failures are material microstructure, stress level, and
temperature. The significance of this type of behavior is that it is dif-
ficult to detect and control. Creep can occur with any FML and may thin the
FML to result in loss of strength and increased vapor transmission. In cases
where a material absorbs liquids from a waste and softens, the material would
be more likely to undergo creep over extended service.
6.3.2.1.3 Shrinkage—Three types of shrinkage can occur with FMLs
during installation and during service and result in excessive stresses that
may cause breaches in the FML or at seams:
- Hot Shrink. This is related to the memory a polymeric sheeting has
while it was being formed at high temperatures (225° to 400°F).
Temperatures on a dark colored sheeting in the hot sun can approach
180°F and, at this point, the sheet begins to shrink sometimes as
much as 2 to 5% of its original length. (Fabric reinforcement is
used to help reduce and control this type of shrinkage).
- "Snapback." This is a rapid recovery of some rolled FMLs when they
are being unrolled at the job site or fabrication facility. "Snap-
back" represents the memory of sheeting resulting from stresses
introduced into an FML at the time it is being wound as a roll
immediately after production, or immediately after fabrication.
Wind-up of sheeting usually occurs at room temperature. "Snapback"
usually results in a shrinkage of approximately 1% of the length of
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the sheeting. (If the sheeting is unrolled and allowed to relax
in-place for one hour, recovery is complete and "snapback" will not
occur.)
- Long-Term Shrinkage. FMLs that contain a volatile component, such as
a plasticizer, can lose this component over time. The losses can
occur by the processes of volatilization, absorption, or extraction.
Since the volatile component represents a given volume of the com-
pound, as this disappears, some type of compensation has to take
place. Either dimensions will change or large forces will develop
which could result in splitting of the FML or the opening of seams.
In addition, shrinkage can result in uplift of the FML off the sub-
grade support at the foot of the slope (i.e. in bridging) which can
result in excessive stresses in these areas.
6.3.2.1.4 Tendency towards environmental stress-cracking--Stress-
cracking is defined as external or internal cracking and breaking of a
plastic caused by tensile stresses less than its short-term mechanical
strength. Under certain conditions of stress and exposure to soaps, oils,
detergents, or other surface-active agents, certain grades of PEs in parti-
cular may fail by cracking in a relatively short time. This phenomenon was
first recognized in PE cable covers and is discussed in Sections 4.2.1.11 and
4.2.2.5.4. Proper selection of the PE resin or addition of one of a variety
of rubbery polymers can eliminate this deficiency.
6.3.2.2 Factors Related to the Site--
Si te-related factors are frequently factors that could have been
mitigated by adequate design provisions. However, these factors may not have
been recognized during the site investigation, or the site investigation
could have been inadequate.
6.3.2.2.1 Subsidence—Subsidence is the settling or sinking of the land
surface due to many factors, such as the decomposition of organic material,
consolidation, drainage, and underground failure. If subsidence occurs in a
landfill or at the bottom of a surface impoundment where sufficient liquid
head exists, it is doubtful whether the FML can move or elongate to compen-
sate without breakage. Subsidence occurring above the waterline in a surface
impoundment might not result in catastrophic failure if the coefficient of
friction between the liner and the soil is not high enough to prevent slip-
page. The FML may compensate over a short term, but the situation created
is not good as long-term creep or seam failure can result.
6.3.2.2.2 Generation of gases underneath the unit—The presence of
organic materialin a soilbelow an FML can generate gases through natural
decay processes. If gases are generated and not vented from underneath an
FML-lined surface impoundment, they may collect and push the FML upward from
the subgrade resulting in a "whale back." Large portions of an FML can rise
up like a balloon out of the liquid. Eventually "whale backs" can rupture
(e.g. at the seams) or will require rupturing to release the trapped gases.
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6.3.2.2.3 Water table—If not accounted for properly in the design, a
rising water table can result in built-up hydrostatic pressures below the
liner and eventually cause uplift or bursting of the liner.
6.3.2.3 Design and Engineering Factors—
These factors are related to the design's inability to account for:
_ Site-specific conditions, such as the type of soil and the quality of
the bedrock underneath the site and the climatological conditions that
could result in heavy rains, freezing of support soils, freeezing of
the waste, etc. In colder climates where ice can form on the
surface of an impoundment, the formation of ice can damage a liner
if taken protective measures were not included in the design. In the
spring months when ice breaks up, large floating chunks can easily
puncture and rip the surface of an FML. Rip-rap and other forms of
slope protection have been used to protect the FML.
- Limitations in how a material such as an FML should be used in a
design for a containment unit. For example, a highly plasticized FML
used without a protective soil cover to line a surface impoundment
located in a region with high levels of solar radiation would probably
fail after a short service life.
- Adequate mechanical compatibility between the different components
of the liner system, such as the proper selection of the sidewall
slopes and bedding layers between an LCRS and an FML. Low coef-
ficients of friction between layered components of liner and drainage
systems on slopes may result in serious slippage of the waste on the
liner and failure of the liner.
- The effects of exposure to the constituents of the waste liquid
or leachate on the properties of the FML.
Ultimately the design for a waste containment unit needs to minimize the
mechanical stresses on an FML because a material under prolongled stress
below its tensile strength will lose strength and may ultimately fail. This
type of long-term failure would probably occur when the material was stressed
biaxially. Several FMLs have been shown to have rather high elongations or
when stretched in one direction at a time, but it has been observed that
biaxial stresses can cause an FML to break or split at low elongations.
6.3.2.4 Factors Related to Construction—
6.3.2.4.1 Poor subgrade compaction—Compaction of the subgrade is an
essential step in obtaining a relatively firm and unyielding support for the
FML. If compaction is poor, then wave action or foot traffic can easily
cause sloughing of the side slopes. Subsidence and differential settlement
can result from added pressures created as the impoundment or landfill is
filled, causing localized strains and possible failure of the FML.
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6.3.2.4.2 Inadequate finishing of the subgrade--Inadequate finishing
of the subgrade could result in the FML being installed on a surface with
sharp, pointed edges that could puncture the FML.
6.3.2.4.3 Poor quality of the seams—According to the available in-
formation, seams in an FML in places where the FML is attached to structures
(e.g. penetrations) are areas that are particularly vulnerable to damage.
Poor quality seams can be a result of attempting to seam the FML under
adverse conditions (e.g. during a storm) or using inadequately trained crews.
These practices can result in seams of insufficient strength, in seam holi-
days, and "fish mouths" which are places where there are wrinkles in one
of the sheets seamed together. The quality of the seaming operation can
significantly affect the ability of the unit to perform as required.
6.3.2.5 Factors Related to Quality Control/Quality Assurance--
Quality control and quality assurance are performed to ensure that the
various components of the lining system meet both materials and construction
specifications. These activities force the construction and installing
contractors to consider the quality of their workmanship throughout the
construction of the unit. Thus, construction decisions that might be made on
the basis of contractor preference, to save time, or to meet a certain
construction schedule would have to be considered in light of their effect on
workmanship. In addition, quality assurance and quality control make the
contractor aware of his level of workmanship, and if there are difficulties
in meeting the specifications, the problem can be corrected prior to a
potential failure.
6.3.2.6 Factors Related to the Service Environment—
6.3.2.6.1 Weathering--FMLs exposed directly to the weather, e.g. on
the slope of a surface impoundment, can be subject to damage from heat
and infrared, UV light, oxygen, ozone, and moisture. These factors generally
operate in combination, with oxygen and moisture being the major contributing
factors. Damage of the FML generally occurs from polymer degradation,
embrittlement, shrinkage related to the volatilization of compound com-
ponents, and cracking. Ozone can cause cracking of many polymers, particu-
larly of certain rubbers (e.g. butyl) that contain unsaturation. Damage of
this type occurs in areas where the rubber sheeting is under stress.
Most damage that occurs as a result of weathering is caused by improper
formulation or misuse of a material, i.e. using a material for outdoor
exposure that should be covered. Considerable information is available
on the durability and service life of exposed FMLs in which the principal
environmental conditions are UV light, oxygen, ozone, and heat (Strong,
1980).
Plasticized compositions may become stiff and brittle on exposure to
weather and to waste liquids. Impact or movement may cause the FML in these
areas to break and thus develop breaches, through which liquids can flow.
Loss of plasticizer can also cause shrinkage and tensioning of the FML.
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6.3.2.6.2 Wind and wave action—Large area surface impoundments are
susceptible to failure from the action of wind and waves. Repeated pounding
of waves on side slopes can eventually cause sloughing. Waves can crest over
the tops of dikes and infiltrate behind the FML thus weakening the slope
structure. Geotextiles, rip-rap, and control of the height of the maximum
waterline can avoid failures.
6.3.2.6.3 Biodegradation—This uncertain factor needs to be observed
in field verification studies as biodegradation may occur in FMLs and the
materials of construction used in liner systems. These effects are long-
term, and few have been observed except under very special circumstances, as
is discussed in Section 4.2.1.12. In general, the high molecular weight
polymers, such as those used in FMLs and other geosynthetics and plastic
pipe, are highly resistant to biodegradation. Biological attack has been
observed with some plasticized FML compositions due to the susceptibility of
some plasticizers and other monomeric constituents of the compound to bio-
degradation. Biocides are sometimes included in compounds to reduce this
type of degradation. It has also been observed that fungal growth can take
place on the surface of a polymeric FML or product without degrading the mass
of the composition.
6.4 DIFFICULTIES IN FINDING AVAILABLE SITES FOR STUDY
AND MATERIAL SAMPLING
FML-lined sites that can be studied or sites where samples can be
taken have been difficult to locate. A number of questions are involved in
studying and sampling in-service FMLs, including proprietary concerns on the
part of the site owner/operator, the installation contractor, and the FML
manufacturer. This is particularly true in cases where there have been
problems with the lining system. It is well recognized that open knowledge
of problems in a waste facility could affect public relations between the
owner/operator and the surrounding communities and could affect the com-
mercial interests of the installation contractor (if problems are related to
workmanship) and the FML manufacturer (if problems are related to the FML's
ability to perform or to shortcomings in the recommended seaming methods).
However, it is the type of information that the engineering profession needs
to improve the design of waste impoundment facilities.
Even given the willingness of the various parties to cooperate, there
may still be questions of liability. For example, it is possible to patch
the sampled area of certain FMLs that have been exposed to weathering for
many years on the slopes of a surface impoundment. However, if the patch
does not hold, there are questions about who will assume liability for the
failed patch and whether it voids the original warranties applied to the
installation and the material.
Lastly, there are also technical and practical problems. For example,
there are no effective and economic methods of sampling FMLs in service at
the bottom of a landfill. In addition, it is not technically feasible to
repair an FML that has been exposed to wastes (Haxo, 1987).
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The most convenient and most complete situation to use as a field
study is a lined unit that is being dismantled. Usually no liabilities are
involved, and there are no limits to the number of samples or to the areas
from which samples can be cut except the construction schedule.
Decommissioning of lined waste containment units under Superfund Re-
medial Actions offers an excellent opportunity for collecting information on
the performance and durability of lining materials. Efforts should be made
to incorporate liner recovery and testing into decommissioning operations
when such sites become available.
6.5 FIELD STUDIES OF FMLS
In this section, field studies of FMLs in service in containment units
are reviewed. A table is presented for each group of cases as an easy
reference guide and is followed by detailed discussion of the observations
and test data where available.
The following is a list of the types of materials referenced in the
case histories presented in this section:
Type of material Number of cases
PVC 10
CPE 6
EPDM 3
CSPE 3
Butyl 2
ELPO 1
LDPE 1
HOPE 1
Asphaltic membrane 1
6.5.1 Field Studies Conducted by Matrecon
Table 6-2 describes nine field sites studied by Matrecon. The principal
objective of these studies was to investigate the effect of service on the
properties of the FML. Samples were taken from the liners at each site and
subjected to laboratory testing to assess the physical and analytical prop-
erties of the exposed samples. Unless stated otherwise, the methods used in
testing the sample FMLs are listed in Table 6-3. Testing was performed as
soon as possible after receipt at the laboratory, and the samples were kept
in a moist condition until testing. Data on three sites are reported almost
in their entirety to give examples of a detailed planned study and investi-
gation of an in-service liner.
6.5.1.1 PVC FML in MSW Demonstration Landfill--
A demonstration landfill in Crawford County, Ohio, was constructed in
the spring of 1971 and lined with a 30-mil PVC FML. It had been designed
6-15
-------
TABLE 6-2. SUMMARY OF FML FIELD STUDIES PERFORMED BY MATRECON
Ol
FML
30-mil PVC,
15-mil PVC,
7 -mil LOPE,
45-mil CSPE
30-mil CPE,
30-mil CSPE
type
unreinforced
unreinforced
un reinforced
, unreinforced
unreinforced
, unreinforced
Type of waste
Refuse waste
Brewery sludge
MSW leachate
MSW leachate
Type of
unit
Demonstration
landfill
Sludge lagoon
Municipal solid
waste landfill
Landfill cells
Years of
Location exposure
Crawford County, OH 6
Northeast U.S.A. 7
Boone County, KY 9
Georgia 4
Comments on FML
Good retention of
original properties.
Deterioration due to
exposure to weather-
ing; good retention
of properties when
buried and exposed
to sludge.
LDPE unaffected;
unreinforced CSPE
swelled; CPE
stiffened.
Some swelling and
curing.
100-mil HOPE, unreinforced Aqueous solution of Waste lagoon
of organics, chlo-
rinated hydrocarbons
Northeast U.S.A.
20-mil PVC, unreinforced Calcium sulfate
sludge, ammonia
and chlorides
20-mil PVC, unreinforced Municipal sani-
tary waste
60-mil EPDM, unreinforced Sludge from pro-
duction of TNT
Industrial sludge Northeast U.S.A
lagoon
30-mil PVC, unreinforced
Industrial waste-
water treatment
sludge from manu-
facture of dyes
and plastics
Landfill
Surge pond
Industrial
landfill
Pennsylvania
Illinois
New Jersey
18
Maintained
integrity, but
was torn by
equipment during
cleanup operations.
Mechanical punc-
turing; field seams
failed.
Good retention of
physical properties;
slight stiffening.
Field seams opened
on slopes; "whale"
formation from gas
generation under
Uner; anchor trench
pull-out.
Stiffened, but still
functional; torn by
equipment during
cleanup.
-------
to compare conventionally-processed solid waste with a shredded waste and
a rough compacted waste. The three types of MSW were placed in cells
competely lined, including the top of the cells, with PVC FMLs. A layer
of clay was placed on top of the FML which was on the bottom of the unit.
TABLE 6-3. METHODS3 USED IN TESTING FML SAMPLES RECOVERED
DURING CASE STUDIES CONDUCTED BY MATRECON
Property Test method
Analytical properties
Volatile MTM-1 (Appendix G)
Ash ASTM D297
Specific gravity ASTM D792
Extractables MTM-2 (Appendix F)
Mechanical properties
Thickness b
Tensile properties ASTM D638, Type IV specimen at 20 ipm
Tear resistance ASTM D624, Die C specimen
Hardness ASTM D2240
Seam strength in shear ASTM D882, 1-in. wide strips
Seam strength in peel ASTM D413, 1-in. wide strips, 90° peel, 2 ipm
aUnless stated otherwise in text.
^Reported thickness values are values resulting from averaging
thicknesses of specimens used in mechanical property testing.
One objective of the demonstration landfill was to determine the effect
of water content on consolidation and decomposition of the refuse, but the
cells were flooded with water in a heavy rainfall just before the cells were
to be sealed. As a consequence, the refuse in all cells was flooded and
probably remained so from 1971 until they were opened in May 1977. When the
cells were opened, and the clay that was placed on top of the FML was tested,
it was found to have a low permeability. Thus, it appeared that the leachate
in the cell had not contacted the FML on the floor of the unit.
The results of testing both the FML exposed at the top of the cell
under two feet of clay and the FML exposed at the bottom of the cell are
reported in Table 6-4. The FML beneath the refuse appeared to have swollen
and softened slightly. There was also an indication that the FML at the top
may have lost some plasticizer. The sheeting itself had sustained con-
siderable distortion during its exposure due to rough ground or to the
pea gravel on which it was placed. Even though there was no retained sample
for comparison, the test values of the exposed sheeting indicated that the
overall properties, including the seam strength, probably changed little
during the exposure.
6-17
-------
TABLE 6-4. PROPERTIES OF 30-MIL POLYVINYL CHLORIDE FML
RECOVERED FROM A DEMONSTRATION LANDFILL IN CRAWFORD COUNTY, OHIO
Matrecon FML identification number 96
Exposure Top of fill
"97A
Bottom of fill
Analytical properties
Volatiles, (2 h at 105°C), %
Specific gravity (dry basis)
Ash (dry basis), ASTM D297, %
Extractables, (dry basis)
ASTM D3421, %
0.41
1.260
6.14
34.10
1.33
1.265
6.01
34.43
Physical properties
Thickness, mil
Tensile strength, psi
Elongation at break, %
Stress at 100% elongation, psi
Stress at 200% elongation, psi
Tear resistance, ppi
Hardness, Durometer points
Puncture resistance
Force at puncture, Ib
Deformation at puncture, in.
Seam strength in shear
Strength at break, ppi
Locus of break3
30
2630
350
1270
1790
372
70A
41.4
0.66
49.5
SE
28
2515
340
1135
1695
342
72A
37.3
0.65
45.5
SE/BRK
aSE = Break at seam edge; BRK = break in specimen outside
seam area.
of
6.5.1.2 PVC FML in Sludge Lagoon--
A disposal unit which contained a brewery sludge and which had been
lined with a 15-mil PVC FML was being closed after having been in operation
for 6.5 years. Both weathered and buried samples were obtained from the
site. Inspection indicated a broad range of effects upon the PVC FML, i.e.
from complete deterioration, where the FML had been exposed to the weather,
6-18
-------
to almost no apparent deterioration where the FML had been under either soil
or sludge. The FML that had been exposed to the weather on the berm had
become so brittle that it fragmented on touch. No retained sample was
available, however, to use as a control for assessing changes. Also, it is
not certain whether any of the FML had been exposed to anaerobic conditions.
The results of testing four areas of the recovered FML are reported
in Table 6-5. The samples taken from under the soil or sludge ranged in
volatiles content from approximately 1% to more than 8%, indicating swelling.
They also ranged in extractables from 29 to 36.7%, indicating that a PVC FML,
even under a cover, can lose plasticizer. These results indicate that the
PVC FML should have been covered and probably should have been thicker than
15 mils.
TABLE 6-5. PROPERTIES OF 15-MIL PVC FML EXPOSED
AT A SLUDGE LAGOON IN THE NORTHEAST FOR 6.5 YEARS
Covered by soil or sludge
Analytical properties
Volatiles, %
Ash (db), %
Specific gravity (db)
Extractables (db)a, %
Physical properties^
Thickness, mil
Tensile at break, ppi
Elongation at break, %
Stress at 100% elongation,
ppi
Stress at 200% elongation,
Ppi
Tear resistance, Die C, Ib
Hardness, durometer points
8.15
4.35
1.31
29.0
15
43.0
225
34.7
41.9
6.7
86A
3.13
3.97
1.25
36.7
16
45.5
375
21.0
29.3
5.0
75A
Exposed to
8.46
5.83
1.32
25.8
16
38.6
175
35.5
• • •
6.8
81A
weather
3.41
* • •
• • •
24.8
11.6
32.1
7
• • •
* » *
• • •
• • •
Extractions performed with a 2:1 blend of carbon tetrachloride and methyl
alcohol (Appendix E).
^Tensile and tear values are averages of machine and transverse directions.
6.5.1.3 CPE, CSPE, and LDPE FMLs in a Pilot-Scale MSW—
The closure of the Boone County Field Site provided an opportunity to
recover CSPE, CPE, and LDPE FMLs that had been exposed to an MSW landfill
6-19
-------
environment for more than nine years (Emcon, 1983). This site had been
operated by the Solid and Hazardous Waste Research Division of the EPA
from 1971 through 1980 (Wigh and Brunner, 1981).
Three samples of a CSPE FML and one sample of an LDPE FML were taken
from Test Cell 1; six samples of a CPE FML were also taken from Test Cell
2-D, four of which had been exposed on the bottom of the cell, and two of
which had been exposed to the weather. All three FMLs were unreinforced, and
all samples, except the two exposed to weathering, had been exposed to
leachate. No retained samples of the original materials were available, nor
were any test data available on the specific lots of sheetings used in these
cells. The results of testing samples of the LDPE, CSPE, and CPE FMLs
exposed to leachate and the CPE exposed to weathering are presented in Table
6-6. Test results for all the CSPE samples were very similar and are aver-
aged in the table.
Test Cell 1 was a trench-type cell, 45.4 m long by 9.2 m wide (Wigh
and Brunner, 1981). The CSPE FML lined the bottom of the unit. A slotted
collection pipe was installed above the transverse center line of the cell.
An 18-in. thick clay liner was installed on top of the CSPE FML and the
collection pipe. A second slotted collection pipe was installed in a trench
in the soil liner directly above the collection pipe on the floor of the
cell. To prevent leachate from by-passing the upper collection pipe and
flowing into the lower pipe, the base and sides of the trench were lined with
a 6-mil LDPE strip.
During the 9-year operation of the cell, leachate that permeated through
the soil liner contacted the CSPE FML. The quantity that permeated through
the soil and was collected was a fraction of one percent of the amount
generated in the cell. The leachate collected in the lower pipe was more
dilute than the leachate that was collected above the clay liner. The CSPE
FML samples showed a substantial absorption of the dilute leachate, which is
indicated by the volatiles contents which ranged from 23.9 to 28.4%. For the
sample that had a 28.4% volatiles content, this is equivalent to a 39%
increase in weight or an increase of 57% in volume based upon the original
composition. This FML was based on a potable-grade compound; industrial-
grade CSPE FMLs which exhibit significantly lower water absorption had not
been developed.
The LDPE film was clear after the surface stain was removed by washing
and appeared to be unaffected by the nine years of exposure to the MSW
leachate. The sample, which had been in direct contact with the more concen-
trated leachate, showed little swelling, and its properties appeared to
be normal for an LDPE FML of 6 to 7 mils thickness.
The samples of the CPE FML taken from the bottom of Cell 2-D had been in
direct contact with the leachate generated in the cell and were stiff and
leathery. They showed a significant absorption of the leachate, as is
indicated by their volatiles contents which ranged from 16.7 to 18.8%. The
volatiles content of 18.8% is equivalent to an increase of 23% in weight
based upon the original, or an increase of 31.7% on the volume basis.
6-20
-------
TABLE 6-6. EFFECTS ON CSPE, LOPE, AND CPE FMLS OF
EXPOSURE IN MSW CELLS AT BOONE COUNTY FIELD SITE FOR 9 YEARS
Property
Analytical properties
Volatiles, %
Ash (db)d, %
Specific gravity (db)
Extractables (db), %
Solvent
Physical properties
Thickness, as received, mil
Thickness, after drying, mil
Tensile at yield, ppi
Breaking factor, ppi
Elongation at break, %
Stress at 100% elongation, ppi
Stress at 200% elongation, ppi
Tear resistance, Ib
Hardness, Durometer
points
Puncture resistance
Force at puncture, Ib
Deformation at puncture, in.
In
CSPEa»b
below clay
layer
26.5
22.4
1.446
3.27
43.8
45. ?e
• * *
52.6
325
19.2
32.4
6.5
57A
34.2
0.89
Cell 1
LDPEC
above clay
layer
* « *
0.15
• • •
1.10
7.0
6.6
9.9
10.6
285
9.6
9.65
2.9
• • •
7.0
0.37
In Cel
CPE*
under
waste
18.8
13.36
1.372
4.81
41.5
39.2
• • •
49.8
280
26.9
39.8
7.3
67A
36.6
0.78
1 2-D
CPEa
above
ground
6.63
13.21
1.34
4.42
34.0
• * »
• • •
64.3
305
37.2
49.1
7.2
71A
46.4
0.68
aNominal thickness = 30 mils.
bAverages of the results on three samples of the CSPE FML; all three
were taken from below the clay layer and had been in contact with full-
strength leachate.
cNominal thickness = 6 mils.
^Dry basis.
eSpecimens shrank and became thicker.
6-21
-------
Data indicated that the samples exposed on the bottom of the cell may have
been based on two different compositions. Two of the samples consistenly
had somewhat lower ash contents, lower volatiles, lower extractables, and
lower stresses at 100 and 200% elongation values. These differences indi-
cate the range of lot to lot variation. In spite of the significant swell of
the CPE sample that had been exposed at the bottom of the cell, the proper-
ties of the swollen CPE were reasonably good.
Compared to the CPE samples that had been exposed to the leachate in the
cell, the weathered samples showed significantly higher tensile strength,
stress at 100 and 200% elongation values, and puncture resistance (Table
6-6). The lower values for the leachate-exposed CPE probably reflect the
swelling by leachate; however, crosslinking or a loss of plasticizer during
exposure may have contributed to the higher values of the weathered samples.
6.5.1.4 CSPE FML in Pilot-Scale MSW Landfill Cells-
Two pilot-scale landfill cells at Georgia Institute of Technology were
constructed and put into operation as part of a research study on the effect
of leachate recycling on the consolidation and stabilization of municipal
solid waste (Pohland et al, 1979). The cells consisted of two adjoining
concrete structures. Both had a 10 x 10-ft base, were 17 ft in height, and
were fully-lined with an unreinforced CSPE FML. One cell was left open at
the top, and the other sealed. Two drain systems were incorporated in the
bottom of each cell, one in the gravel layer above the FML and one in the
gravel layer between the FML and the concrete base. Shredded MSW was added
to the cells and compacted to a density of 540 Ib yd"3. Another layer of
gravel with the leachate distribution system was placed above the compacted
waste. Two feet of soil were then added to cover the cell. The amount of
rainfall reaching the open cell was monitored, and an equivalent amount of
water was added to the closed cell.
After four years of operation, the cells were emptied and the FMLs
recovered. The FMLs were exposed to a variety of conditions within the two
cells, the different effects of which could be measured. The FML in the cell
open at the top encountered weathering and sunlight exposure at the level
of the soil cover, and exposure to the waste. The FML in the sealed cell
encountered the moist air in the cell above the soil, the soil, and the
refuse.
The data on the different exposures are presented in Table 6-7. In
particular, they show the greater absorption of leachate and moisture by
liners in the soil and in the waste. They also show the difference between
the liner that was on the north wall facing south and that on the south wall
facing north. The sheeting on the north wall yielded the greatest increase
in modulus and in cure. The lower ash number for the samples exposed at the
bottom of the cells are probably due to incomplete volatilization of the test
specimens at the time of analysis.
6-22
-------
TABLE 6-7. EXPOSURE OF CSPE FML WITHOUT FABRIC REINFORCEMENT IN
PILOT-SCALE MSW LANDFILL CELLS AT GEORGIA INSTITUTE OF TECHNOLOGY
c ,, Open cell Closed cell
Compass orientation N SE N SW SW N E
Level in cell Above Above In Below Above In Below
soil soil soil waste soil soil waste
Thickness, mil
Analytical properties
Volatiles, %
Asha (db), %
Extractables (db), %
Ortl \i f\ r^4-
oo i vent
Physical properties^
Tensile at break, psi
Elongation at break, %
Set after break, %
Stress at 100%
elongation, psi
Stress at 200%
elongation, psi
Tear resistance, ppi
29.1
3.62
41.9
...
2380
360
95
655
930
200
29.1
9.01
39.9
1.50
2190
350
72
610
740
140
31.9
13.8
40.3
...
1740
545
227
405
510
187
52.8
23.7
38.2
...
1335
485
170
320
420
151
33.1
2.3
40.6
2.00
1770
570
206
420
510
213
34.3
19.0
40.7
...
1450
545
206
280
375
159
39.0
26.5
38.3
...
1450
485
154
335
450
138
Puncture resistance
Thickness, mil 30.7 22.0 34.5 40.3 32.7 36.4 41.2
Force at puncture,
Ib 36.8 27.9 33.4 41.6 27.3 33.9 39.0
Deformation at
puncture, in. 0.88 0.51 1.33 1.61 1.12 1.72 1.71
Hardness, Durometer
points 76A 78A 64A 56A 75A 60A 51A
Seam strength
Shear, ppi 33.4 ... 35.5 30.0 40.5 34.3 22.2
Peel, average, ppi 17.4 ... 14.2 12.4 14.2 15.8 13.8
Determined by thermogravimetric analysis.
^Tensile and tear values are averages of machine and transverse
directions.
6-23
-------
6.5.1.5 HOPE FML in a Hazardous Waste Lagoon--
Samples of a 100-mil HOPE FML were recovered from a waste lagoon in the
northeastern United States after 4.75 years of service (Nelson et al, 1985).
Samples were removed from different locations in the lagoon and tested to
determine the effects of exposure on the physical properties of the FML. The
recovery was performed during closure of the lagoon in a Superfund Remedial
Action. The site was single-lined unit. The impounded waste liquid was
predominantly aqueous and contained significant amounts of organics, parti-
cularly chlorinated hydrocarbons, which increased in concentration with
depth.
Overall, the FML appeared to be in satisfactory condition. No evi-
dence indicated that it had cracked or failed, but it did show considerable
waviness and distortion on the berm and slopes. The results of testing the
samples indicated that the samples from the bottom of the lagoon showed an
absorbed waste content of about 2%; they also showed a 10% loss in tensile
strength at yield and similar losses in the stress at 100% elongation
and in the stress at 200% elongation values and a 30% loss in modulus of
elasticity. The samples taken from the slopes of the lagoon showed es-
sentially no changes in physical properties. Construction equipment was used
in an attempt to remove the waste without damaging the liner, but the liner
on the bottom of the lagoon was, nonetheless, destroyed during the cleanup
operations. The following subsections discuss the sampling and analysis of
the waste, sampling of the FML, and the results of testing the FML samples.
6»_5_.l. 5_.1_ Sampl ing and analysis of the waste—The decommissioning
justiffeationdocument(EPA,1983)indicatedthatin July 1983 sediment
samples of the lagoon waste were collected from a small boat from each of
the four corner areas, as is indicated in Figure 6-1. The sump, which is
located at the northwest corner, is the deepest point of the lagoon, and the
southwest corner is the shallowest. Aqueous waste samples were collected at
the northwest corner, the center, and the southeast corner (Figure 6-1).
Different depths were sampled at each point.
The sediment that was directly on the lagoon liner underwent limited
testing. Data on its physical and chemical properties, which are presented
in Table 6-8, show the range in sediment composition at the four sampling
points. The low flash point and high energy value for the sump sediment
indicate the presence of organic solvents, which tend to be aggressive to
most lining materials.
The aqueous waste samples were analyzed more thoroughly. Tests were run
for inorganic and organic priority pollutants, priority pollutant pesticides,
PCBs, and other inorganics. Samples were taken from three or four depths at
each of the three collection points. Concentrations of most constituents
increased with depth, showing that the lagoon waste had stratified. Samples
taken from the greatest depth at each collection point are of greatest
interest in terms of the FML, since they represent the waste closest to the
liner on the lagoon bottom. Data on the organic constituents of these
6-24
-------
9-
8-
7-
6-
5-
4-
3-
2-
1-
A B C D
ii T i
• 8
: 1 0' deep
\ SUMP
= t
: S,W
- Bi
:
! 7' deep
: S
E F G H I
I I II!
A6
S j
W j
2 j
• :
S,W '-
j^ —
E 4
m
i
-M-
-TOE OF
SLOPE
0,20 feet
Figure 6-1. Lagoon lay-out showing grid pattern used in sampling, points of
sample collection, and location of sump (©). Locations at which
liner was sampled are indicated by • and the liner sample
number, sediment samples are indicated by S, and aqueous waste
samples are indicated by W. The toe of the slope is indicated
by a hatched line (++++). (Source: Nelson et al, 1985).
TABLE 6-8. PHYSICAL AND CHEMICAL PROPERTIES OF SEDIMENT SAMPLES
COLLECTED FROM A WASTE LAGOON LOCATED IN THE NORTHEASTERN UNITED STATES3
Point of sampling
Parameter
Lagoon sump
B-2
G-7
6-3
PH
Flash point,
Corrosivity
Ignitabi1ity
Energy value^,
5.4 8.6
26 >60
Noncorrosive Noncorrosive
10.3
>60
Noncorrosive
10.3
>60
Noncorrosi ve
Ignitable Not ignitable Not ignitable Not ignitable
BTU/lb
Total residue, %
7880
19.84
• • •
56.83
• • •
7.89
• • •
13.19
aData taken for the decommissioning justification document.
^Dry-weight basis.
6-25
-------
samples, which are the most concentrated for each sampling point and hence
the most aggressive, are summarized in Table 6-9. Because inorganic chemi-
cals are not generally aggressive to polymeric FMLs, the high concentrations
(greater than 50 ppm) of copper, nickel, zinc, and iron should not affect the
HOPE. On the other hand, phenols and petroleum hydrocarbons (71 and 2100
ppm, respectively, in the sample from the lagoon sump) could have some impact
on the FML. The total organic carbon (TOC), which was greater than 6000 ppm
in all three of the deepest samples, could also affect the FML. The analyses
of organic priority pollutants indicated the presence of several aggressive
chemicals at concentrations greater than 50 ppm in the sample from the sump.
Chlorinated solvents are known to cause swelling and deterioration of physi-
cal properties in HOPE FMLs. The analyses of aqueous waste samples from the
greatest depth at the three sampling locations resulted in the detection of
only minute amounts of the PCB Aroclor 1254 in two of the samples.
TABLE 6-9. CHARACTERISTICS AND COMPONENTS OF THE WASTEWATER
THAT ARE POTENTIALLY AGGRESSIVE TO FMLS
Sampling point and depth*3
Waste component or characteristic
6-3
3.0 ft
E-5
4.0 ft
Lagoon sump
6.5 ft
Organic priority pollutant, mg L~l;
Chloroform
Ethyl benzene
Methylene chloride
Tetrachloroethane
Trichloroethane
Toluene
1,1,1-Trichloroethane
1,2-Dichlorobenzene
2.65
3.30
102
1.7
28.6
10.4
0.31
0.96
3.2
9.6
140
3.8
90.2
24.5
• • •
1.89
56.6
1080
325
182
9100
522
50.0
151
Other:
Phenols, mg L~l
Total organic carbon, mg L~l
Petroleum hydrocarbons, mg L~l
pH
Flash point, °C
20
6950
26.0
9.7
>60
32
8230
27.8
9.6
>60
71
17200
2100
9.8
>60
aData taken from the lagoon decommissioning document.
^Samples were taken from the greatest depths at three locations in
the lagoon (see Figure 6-1).
6.5.1.5.2 Sampling of the FML liner--The liner was inspected and
samples were collected for analysis and testing on February 2, 1984. The FML
on the upper area of the lagoon was distorted and buckled but in good condi-
tion. In the lower area of the lagoon slopes, the FML was scratched and had
6-26
-------
many holes and tears. In one place a rock had penetrated the FML. Samples
of tears and creases were collected from these areas. Two samples were
removed from the sludge mixture on the floor of the lagoon. An 18-in.-wide
strip was cut from the northwest corner of the lagoon; the
bottom of the lagoon to near the top. A sample of HOPE
exposed to waste was cut from a roll of sheeting left from
outer weathered layer was pulled back and a sample was cut
strip ran from the
that had not been
construction. The
from the inside of
the roll. Samples collected are described in table 6-10 and their locations
in the lagoon are shown in Figures 6-1 and 6-2. No sample could be obtained
from the bottom of the sump where the highest concentration of organic
constituents were measured.
TABLE 6-10. FML SAMPLES COLLECTED FROM THE 100-MIL HOPE LINER
FOR A LAGOON LOCATED IN THE NORTHEAST
Sample
number Location in lagoon Size, in. Feature
la Lagoon bottom, south-center 14 x 16
2 Lagoon bottom, southeast corner 10 x 19
3a Retained sample from roll 10 x 15
stored on site, northeast
of lagoon
4 Lower slope, southeast corner 10 x 12
Lower slope, south side 14 x 11
6a Lower slope, north side 6 x 26
7a Bottom to midway of slope, 18 x 69
northwest corner
8a Midway to top of slope, 18 x 114
northwest corner
Sample with
crack/tear
Sample with
tear next to
extrusion line
Pleated sample
with two sharp
creases
Strip cut from
bottom to top,
bottom half
Strip cut from
bottom to top,
top half
aAnalyzed and physically tested.
6-27
-------
Northwest
See Northwest Detail
Sump
20 feet
i
Southwest
See Southwest Detail
Northwest Detail
Northwest Edge
10'deep
Southwest Detail
Southwest Edge
7' deep
Samples 4, 5. 6
Samples 1, 2
Figure 6-2. Cross section of the lagoon from the northwest to southwest
corners. The approximate depths at which FML samples were
collected are shown in the details.
6.5.1.5.3 Analytical and physical testing of the FML samples—The FML
samples were photographed, measured, and diagrammed upon receipt at the
laboratory. Descriptions of these samples and their respective locations
in the lagoon are presented in Table 6-10. The following samples were
selected for full testing:
- Sample 1, exposed liner from bottom of lagoon.
- Sample 3, retained, unexposed FML left in roll on site.
- Sample 7, cut from the lower end of the strip, i.e. at the slope
bottom.
- Sample 8-mid, cut from the middle section of the strip, midway up
slope.
- Sample 8-top, cut from the top of the strip at top of slope.
6-28
-------
These samples were tested as follows:
Property Test method
Analytical properties:
Volatiles content MTM-la (Appendix G)
Extractables content MTM-23 (Appendix E)
Specific gravity ASTM D792
Thermogravimetric analysis ...
Differential scanning calorimetry
Headspace GC analysis ...
Physical properties:
Tensile properties ASTM D638, Type IV dumbbell, 2 ipm
Modulus of elasticity ASTM D882, modifiedb
Tear resistance ASTM D1004, 2 ipm
Puncture resistance FTMS 101C, Method 2065 (U.S. GSA,
1980)
Hardness ASTM D2240
aMTM = Matrecon Test Method.
^Modified so as to allow for the use of 0.5 x 6-in. strip specimen with
an initial jaw separation of 2.0 in. at the standard strain rate of
0.1 in./in. min.
Results of the testing are summarized in Table 6-11. To assess the
effect of depth on the volatiles content of the liner, additional volatiles
testing was performed on specimens cut at 2-ft intervals along the strip,
which consisted of Samples 7 and 8 (Table 6-12).
In addition to the volatiles and extractables analyses of the HOPE
samples removed from the lagoon, thermogravimetric analysis (TGA), differen-
tial scanning calorimetry (DSC), and specific gravity determinations were
performed. The results are presented in Table 6-13 where they are compared
with data from Matrecon's database on HOPE sheeting for U.S. and German-
produced HOPE FMLs. The following observations were made:
- The sample from the lagoon bottom had a lower amount of crystallinity
than the retained sample from the roll and the creased sample from
the side slope.
- The retained and the creased samples had lower melting points and
slightly higher crystallinity than the similar German sample.
- Overall, the data on the retained liner sample and those in the
database on German membranes appeared similar to each other and
different from those on the U.S.-produced sample.
6-29
-------
TABLE 6-11. PROPERTIES OF HOPE LAGOON LINER AFTER APPROXIMATELY 4.75 YEARS IN SERVICE
Properties
Analytical properties
VoUtiles, total loss, %
Over desiccant at 50°C
In oven for 2 h
at 105°C
Extractables, %
Physical properties
Thickness, mil
Tensile at yield, psi
Elongation at yield, %
Tensile at break, psi
Elongation at break, %
Stress at 100% elongation,
psi
Stress at 100% elongation,
psi
Modulus of elasticity,
10* psi
Tear, ppi
Puncture resistance:
Thickness, mil
Force at puncture, Ib
Deformation at puncture,
Hardness, Durometer points
Instant reading
5-second reading
Direction
of test
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
in.
Unexposed
sample of
similar
HOPE
0.06
...
...
...
103.0
2445
2440
20
15
4635
4445
1025
1010
1765
1710
1765
1720
7.86
7.87
839
850
98.5
131
0.73
55D
Sampling location
Retained
sample3,
No. 3
0.15
0.12
0.03
0.00
102.3
2705
2700
17
15
3530
4065
785
860
1920
1945
1930
1940
8.69
8.20
900
885
106
148
0.66
600
57D
Slope
top, No.
8-top
0.22
0.15
0.07
1.26
93.4
2720
2835
18
15
4810
4355
965
875
1960
1965
1955
1963
8.98
8.68
920
910
98.5
139
0.72
58D
55D
in lagoon and sample number
Slope
midway up,
No. 8-tnid
0.56
0.30
0.26
0.80
103.6
2725
2700
17
15
4510
4885
925
985
1925
1925
1920
1925
8.72
8.51
910
890
101
135
0.62
59D
56D
Slope
bottom,
No. 7
1.00
0.64
0.36
1.18
100.6
2650
2665
15
18
3605
2735
760
640
1875
1965
1870
1955
8.37
7.54
855
875
100
134
0.61
590
56D
Lagoon
bottom,
No. 1
2.26
1.90
0.36
0.80
92.4
2445
2440
15
17
3710
388b
810
845
1795
1790
1835
1790
5.97
6.05
830
830
93.1
118
0.59
58D
54D
aSample from unused roll left onsite.
6-30
-------
TABLE 6-12. VOLATILES CONTENT OF SPECIMENS OF THE HOPE FML TAKEN AT INCREASING DEPTHS IN THE WASTE LAGOON
Sampling location along slope from top to bottom
Volatiles
Total volatiles, X
Over desiccant
at 50°C, X
In oven for
2 h at 105°C, X
Retained
sample,
No. 3
0.15
0.12
0.03
Slope
top,
0 ft«
0.22
0.15
0.07
Slope,
4 fta
0.24
0.12
0.12
Slope,
6 ft«
0.35
0.14
0.21
Slope,
8 ft»
0.51
0.29
0.22
Slope,
10 ftb
0.56
0.30
0.26
Slope.
12 ftb
1.08
0.73
0.35
Slope,
14 ft&
1.26
0.82
0.44
Slope
16 ftD
1.00
0.64
0.36
Lagoon
bottom,
8 ftc
2.26
1.90
0.36
aCut from Sample 8 section of 18-in. wide strip taken from top to bottom of slope.
bCut from Sample 7 section of !8-1n. wide strip taken from top to bottom of slope.
cCut from Sample 1 taken from the lagoon bottom which was about 8-ft deep at that point.
TABLE 6-13. COMPARISONS OF THE TGA, DSC, AND SPECIFIC GRAVITY OF THREE HOPE FMLS
HOPE lagoon FML sample a cjm
Analytical properties
Thermogravimetric analysis
Volatiles, X
Polymer, X
Plasticizer, X
Carbon black, X
Ash, X
Differential scanning calorimetery
Tmc, °C
AHfd, cal/g
Crystallinity6, X
Specific gravity
Bottom*,
No. 1
0
97.6
0
1.7
0.7
131
29.8
43.6
0.936
Top, Retained,
No. 8 No. 3
0
97.7
0
1.8
0.5
130
35.3
51.6
0.947 0.943
Creasedb, German
No. 6 Smooth
0
98.1
0
1.9
0
129 123
36.0 33.6
52.6 49.1
0.943
:ilar
liner
Rough
0
98.6
0
1.4
0
124
33.7
49.2
0.939
U.S. FML
(domestic
material )
0
97.7
0
2.3
0
119
24.8
36.2
0.957
aSample had thoroughly dried out during shelf aging before being tested.
^Sample taken at the apex of the crease in the pleat.
cMelting temperature of crystalline phase.
dHeat of fusion of crystalline phase.
Percent crystallinity based on AHf value of 68.4 cal/g for 100X crystalline HOPE.
6-31
-------
The results of the volatiles and extractables measurements indicated
that the HOPE FML had absorbed constituents of the waste. Also, as could be
seen by the relatively low modulus and hardness values for the sample exposed
at the lagoon bottom, the HOPE FML had softened on exposure. Since the
impounded waste liquid contained significant amounts of organics that could
be absorbed to some extent by the HOPE, as can been seen by the data reported
in Table 6-9, tests were explored as methods of identifying which organics in
particular were absorbed. To detect the volatile organics, headspace GC and
GC pyroprobe were explored as qualitative tests. The headspace GC method is
described in Section 4.2.2.5.1 (p 4-94). A large variety of organics ap-
peared to have been absorbed. Some of the volatiles specifically listed in
the analyses in Table 6-9 were identified by headspace GC, and some non-
volatile plasticizers were also identified, indicating the potential use-
fulness of the HSGC procedure.
6.5.1.5.4 Discussion and conclusions—The amount that the FML swelled
(as evidenced by the volatiles content) increased with depth into the lagoon.
The bottom sample (No. 1) contained about 2.3% volatiles, and the sample from
the top of the strip (No. 8) contained approximately 0.2% volatiles. The
retained sample from the roll (No. 3) also had about 0.2% volatiles. All
five of the tested areas (the four exposed to waste and the retained sample)
showed good physical properties, but the sample from the bottom of the lagoon
(No. 1) was the softest (lowest durometer and modulus) and showed the lowest
values for several physical properties. The sample from the bottom end of
the slope strip (No. 7) had low values in tensile at break in the transverse
direction. This sample was observed during testing to be quite scratched,
which probably explains the low values. Data for other FML properties from
this area are much higher. The sample from the top of the strip (No. 8)
showed higher tensile properties than the retained sample (No. 3).
The exposed FML sample from the lagoon bottom showed a small amount of
swelling (about 3%) and 10% loss in both tensile at yield and in modulus.
These changes do not demonstrate incompatibility, but they do indicate that
the waste at the bottom of the lagoon had the greatest impact on the FML.
Much buckling and distortion of the FML was observed, especially on
the north slope of the lagoon. The day the samples were taken was cold but
sunny, which should have minimized any thermal expansion. On a hot day, this
buckling would have been greatly increased. Though not in itself a signifi-
cant problem, buckling adds stress on seams, allows movement of the underly-
ing earthwork by creating cavities, and increases the chance of mechanical
damage by introducing folds.
The FML showed no cracking such as that encountered with environmental
stress-cracking; it lost in tensile strength at yield and in ultimate
tensile strength, but it did not crack at folds or bends.
No evidence was apparent to indicate that the HOPE FML lost its in-
tegrity. All visible seams looked secure. The only evidence of degra-
dation was mechanical damage in areas where the FML had probably been worked
on with a bobcat. The presence of rocks directly underneath the liner
6-32
-------
aggravated this damage. The FML in this impoundment was not able to with-
stand the clean-up operations.
The DSC data indicated that the amount of PE crystallinity in the HOPE
FML changed during exposure, a factor that should be checked in future
testing.
6.5.1.6 PVC FML in an Industrial Sludge Lagoon—
In August and September, 1982, Malcolm Pirnie, Inc. (Roberts et al,
1983) collected samples of a 20-mil PVC FML from an industrial sludge lagoon.
The lagoon was scheduled to be excavated and relined due to failue of the
lining system and, as such, it was possible to obtain samples of the exposed
FML.
The site, located in the northeastern United States, was constructed in
1973. The lagoon covered approximately 22,000 square feet with a side slope
of 2:1. The PVC FML was fabricated by the supplier in two pieces and seamed
in the field by the installer. All seams were made using a bodied solvent.
The FML was designed to be covered but it was observed that the cover ma-
terial had sloughed off at the top of the berm. The lagoon was used as a
settling basin where a slurry waste was pumped in, the solids allowed to
settle, and the liquid pumped back into the plant.
The waste disposed of in the lagoon was a calcium sulfate sludge, the
result of the neutralization of sulfuric acid with lime. The sludge also
contained ammonia and chlorides. A general analysis of the waste liquid in
the lagoon is presented in Table 6-14; this is probably the best representa-
tion available of the liquid in contact with the inside of the FML on the
saturated sludge portion of the lagoon slope.
TABLE 6-14. GENERAL ANALYSIS OF SLUDGE LIQUID
pH 8.0 - 9.0
Specific conductance,
umhos cm'1 15,000 - 60,000
Chlorides, mg L'1 4,500 - 5,000
Sulfates, mg L'l 15,000 - 20,000
Ammonia, mg L"1 1,000 - 7,000
Six FML samples were taken from the upper edge of the lagoon in August,
1982. Subsequently, 12 additional samples were taken from the lagoon side
and bottom in September, 1982, when the lagoon was being excavated. The FML
6-33
-------
sampling locations are shown in Figures 6-3 and 6-4. Field observations on
the FML samples are presented in Table 6-15.
APPROXIMATE
EDGE OF
SATURATED
ZONE
[-^PROXIMATE LOCATION
OF FIELD SEAM
si-.-/ (iv i ^ V--3
yU/^^::';&: \~^f7^: t ^. •* -^fe
X^PV ' lV-4''''-S^--O •''•*' ' V"'"'*'* (4 >^"V *;'.•' L"ii« .'.'••• ifiUjT'-^J
5^^
-------
APPROXIMATE GROUND-HATER LEVEL
UNSATURATEO SLUDGE
(Fluctuates)
SATURATED SLUDGE
(15) 00
3 0 3 6
VEHTICAl SCALE IN FEET
Figure 6-4. Idealized cross section of lagoon showing sample locations.
(Source: Roberts et al, 1983).
The following samples were selected for testing:
- Sample 1 (upper and lower halves).
- Sample 3 (upper half).
- Sample 4 (upper and lower halves).
- Sample 5 (seamed area).
- Sample 6 (upper half).
- Sample 7 (seamed area).
- Sample 11 (seamed area).
- Sample 12 (upper and lower halves).
- Sample 15 (seamed area).
- Sample 17 (seamed area).
6.5.1.6.1 Inspection and testing of the FML samples—Samples of the FML
exposed to weathering were generally brittle and dry. During the sample
collection, the brittleness was evident through cracking and splitting of the
material. However, it was possible to roll up the FML samples, probably
because of the warm weather. The tautness of the FML indicated that lo-
calized shrinkage of the FML had occurred. Tensile test specimens from the
6-35
-------
TABLE 6-15. FIELD OBSERVATIONS OF FML SAMPLES FROM AN INDUSTRIAL SLUDGE LAGOON
Sample
number
Location 1n lagoon
Seams
Conditions of sample
North side of lagoon
Upper half weather-exposed
Lower half exposed to unsaturated sludge
West side of lagoon, northern corner
Upper half weather-exposed
Lower half exposed to unsaturated sludge
West side of lagoon
Upper half weather-exposed
Lower half exposed to unsaturated sludge
South side of lagoon.
Upper half weather-exposed
Lower half exposed to unsaturated sludge
East side of lagoon
Completely exposed to weather
East side of lagoon
Upper half weather-exposed
Lower half exposed to unsaturated sludge
East side of lagoon near lagoon bottom
Completely under saturated sludge
Factory seam 1n both halves
Factory seam 1n upper half
Factory seam In upper half
Factory seam 1n both halves;
unadhered field seam 1n upper
half; Intact field seam in
lower half
Factory seam
Factory seam In upper half
Upper half cracked, brittle
Lower half supple
Upper half brittle, ripped;
shows discoloration; lower
half supple
Upper half brittle, cracked,
grass growing through hole
In FML; lower half supple
Upper half brittle, cracked;
lower half supple
Discolored, supple
Upper half brittle, cracked;
lower half supple
Dimpled sludge in spots; layover
hydrogen sulflde smelling, peat-
like black soil
8
9
10
11
12
13
14
IS
16
17
Bottom sample from southern end of lagoon
East side of lagoon near lagoon bottom
Completely under saturated sludge
South side of lagoon near lagoon bottom
Completely under saturated sludge
Under north berm-folded portion Factory seam
Exposed to soil, same possible
exposure to sludge
North side of lagoon on slope Factory seam
Upper half in unsaturated sludge
Lower half 1n saturated sludge
North side of lagoon on slope •••
Completely under saturated sludge
Bottom sample from lagoon center
Bottom sample from lagoon center Factory seam
Bottom sample from northern end ...
of lagoon
Bottom sample from northern end Factory seam
of lagoon
Dimpled, supple
Dimpled, supple, layover peat-
like black soil similar to 17,
lay under layered sludge
Two creases 1n sample; layover
peat-like black soil similar
to 17
Dry, fairly stiff
Lower half dimpled, supple
Dimpled, supple
Dimpled, supple
Dimpled, supple
Dimpled, supple
Dimpled, supple
Source: Roberts et al, 1983.
6-36
-------
top of Sample 1 cracked along the edges when they were dried out. An attempt
was made to avoid the cracks by dieing specimens from a warmed sample, but
these also cracked. The result of the tensile and tear testing reflect this
brittleness.
Sample 5, which was taken near the discharge pipe, was discolored and
not brittle. This lack of brittleness was in contrast to the rest of the
weather-exposed samples. Their brittleness, because of the loss of plasti-
cizer, is shown by low values for extractables content and elongation and
high hardness values. Sample 6, located adjacent to Sample 4, was brittle
and is a better example of west-facing exposure. Sample 5 is considered to
be nonrepresentative of a weather-exposed sample because of exposure to the
discharge material.
Results of the testing are summarized in three tables. Table 6-16
presents data on the samples exposed to the weather arranged in order of
decreasing severity, i.e. south-facing exposure was the most severe, followed
by west-facing, then east-facing, with north-facing the least severe. In
Table 6-17, the data are presented in a vertical cross section arranged from
the top of the lagoon to the bottom.
6.5.1.6.2 Potential Use of soil-exposed specimen as a control—The
soil-exposed specimen (Sample 11) was collected as a possible control samp!e.
However, the extractables content of the sample, which was 26.50%, is low for
this type of FML and the modulus values are high, which indicates that
exposure probably affected its properties. Due to the nature of the cleaning
operations at the lagoon, the sample may have been exposed at some point
during the operation to the weather and possibly to the sludge. Because of
the rather large apparent loss in plasticizer, the sample is likely to have
undergone moderately severe exposure conditions; therefore, it could not be
used as a control.
6.5.1.6.3 Inspection and testing of the seams—Factory seam samples
from different levels in the lagoon and one sample of the field seam were
collected. All seams were made with a bodied solvent. The factory seams are
approximately 1 in. wide and the field seam approximately 2 in. wide. All
seam samples appeared to run parallel to the machine direction; thus, testing
across the seam constituted a transverse direction test with respect to the
sheeting. All factory seams were observed to be in good condition.
The seams were tested in both shear and peel modes, the results of which
are reported in Table 6-18. Seam strength tested in shear of the factory
seams generally was good ranging from 74% to 99% of the breaking strength of
the FML. Specimens broke either at the seam edge or in the liner material.
The brittle weathered samples and the samples from the bottom of the lagoon
had the lowest seam strength in shear; the sample exposed mainly to soil
(#11) had the best strength. All of the seams tested in peel delaminated
in the plane of the adhesive or "glue line", leaving traces of bodied solvent
on both sides. The lowest peel strength, 17.7 ppi, was measured in samples
from the bottom of the lagoon; the highest, 27.0 ppi, from a weather-exposed
sample.
6-37
-------
TABLE 6-16.
PHYSICAL AND ANALYTICAL PROPERTIES OF WEATHERED SAMPLES OF PVC FML
EXPOSED IN A CALCIUM SULFATE SLUDGE LAGOON
01
i
OJ
CO
Sample number
Lagoon location
Exposure condition
Average thickness, mil
Analytical properties3
Volatiles (as received):
Total, %
Step 1, over desiccant at 50°C, %
Stept 2, in oven at 105°C for 20
Extractables (db), %
Ash (db), %
Physical properties,
as received
Tensile at break, psi
Elongation at break, %
Set after break, %
Stress at 100% elongation, psi
Stress at 200% elongation, psi
Tear resistance, ppi
Puncture resistance:
Thickness, mil
Force at puncture, Ib
Deformation at puncture, in.
Hardness, Shore D
Instant reading
5-second reading
h, %
Direction
of test
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
11
N-side
Under soil
18.8
1.09
0.75
0.34
26.50
7.54
2940
3135
260
285
165
165
2345
2280
2700
2715
535
580
19.8
37.6
0.44
45
38
1 Upper
N-side
Weather
16.0
3.15
1.37
1.78
18.91
8.19
2430
3015
5
25
1
15
...
...
• * •
• • •
235
170
16.7
9.2
0.22
52
49
6 Upper
E-side
Weather
15.6
3.96
3.68
0.28&
20.23
...
2500
2470
25
20
20
3
• • •
• • •
• « *
• • •
295
327
16.8
16.2
0.35
52
50
5
E-side
Weather
19.3
3.22
1.04
2.18
30.52
6.45
3310
3205
205
225
125
130
2810
2585
3240
3405
560
495
18.3
33.1
0.42
52
38
3 Upper
W-side
Weather
16.0
5.18
4.26
0.92
20.54
7.50
3390
3155
80
55
50
50
• • •
• • •
• • •
• • •
515
355
17.4
25.2
0.26
53
48
4 Upper
S-side
Weather
18.2
2.28
1.56
0.72
21.91
8.41
2925
2795
115
70
90
50
2895
2645
• « *
...
595
430
16.0
26.4
0.28
55
47
adb = Dry basis.
bAt 105°C for 4 hours.
Source: Roberts et al, 1983.
-------
TABLE 6-17.
PHYSICAL AND ANALYTICAL PROPERTIES OF SAMPLES FROM A VERTICAL CROSS SECTION
OF PVC FML EXPOSED IN CALCIUM SULFATE SLUDGE LAGOON
I
CO
Sample number
Lagoon location
Exposure condition
Average thickness, mil
Analytical properties3
Volatiles (as received):
Total, *
Step 1, over desiccant at 50°
Step 2, in oven at 105°C for
Extractables (db), %
Ash (db), %
Physical properties,
as received
Tensile at break, psi
Elongation at break, %
Set after break, *
Stress at 100* elongation, psi
Stress at 200% elongation, psi
Tear resistance, ppi
Puncture resistance:
Thickness, mil
Force at puncture, Ib
Deformation at puncture, in.
Hardness, Shore D
Instant reading
5-second reading
11
N-side
Undersoil
18.8
20 h. %
Direction
of test
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
1.09
0.75
0.34
26.50
7.54
2940
3135
260
285
165
165
2345
2280
2700
2715
535
680
19.8
37.6
0.44
45
38
1 Upper 1 Lower 4 Lower 12 Upper 12 Lower 7
N-side N-side S-side N-side N-side W-side
Weather Weather/waste Weather/waste Unsaturated Saturated Saturated
interface waste waste waste
16.0 20.3 20.8 21.2 21.6 20.4
3.15
1.37
1.78
18.91
8.19
2430
3015
5
25
1
15
• • *
• * •
235
170
16.7
9.2
0.20
52
49
6.51
5.10
1.41
21.50
7.90
2915
2575
220
220
125
110
2350
2090
2830
2460
520
355
20.4
31.6
0.33
49
47
3.66
3.14
0.52
26.10
9.32
2780
2495
275
295
105
130
1885
1720
2350
2065
495
415
21.1
40.1
0.64
39
32
10.58
8.62
1.96
31.02
6.89
2610
2315
300
310
95
100
1635
1340
2105
1750
345
330
21.2
35.2
0.66
40
28
9.87
8.27
1.60
32.71
6.67
2505
2335
295
330
70
90
1500
1205
2010
1630
330
310
21.6
32.3
0.71
36
25
7.14
5.60
1.54
32.44
7.13
2605
2440
280
300
85
90
1740
1580
2210
2010
380
360
21.2
31.8
0.63
40
30
15
Center
Lagoon
bottom
19.8
4.27
3.42
0.85°
34.98
7.08
6460
2320
310
315
70
80
1265
1245
1805
1700
260
270
19.7
26.1
0.69
34
24
17
N-end
Lagoon
bottom
20.7
3.43
2.49
0.94
35.15
6.69
2760
2550
265
290
60
70
1625
1415
2208
1975
325
295
20.5
32.6
0.67
39
24
a
-------
TABLE 6-18. SEAM STRENGTH OF PVC FML EXPOSED IN CALCIUM SULFATE SLUDGE LAGOON
Sample number 1 Upper 1 Lower 3 Upper 4 Upper 4 Lower 5 7 11 12 Upper 15 17
Exposure conditions Weather Weather/waste Weather Weather/waste Weather/waste Weather Saturated Soil Unsaturated Bottom Bottom
Interface Interface Interface waste waste
Breaking factor, ppl
Transverse direction 48.3 49.7 52.1
Factory seam strength:
Shear, ppl 43.9 46.8 40.3
Locus of break" SE-BRK SE-BRK SE
Percent of breaking factor 91 94 77
Peel, ppl 27.0 21.3 26.1
Locus of break« AD AD AD
Field seam strength:
Shear, ppl
Locus of break8
Percent of breaking factor
Peel, ppl
Locus of break"
51.7 52.5 62.0 49.4 54.3
38.4 44.2 51.8 44.8 53.8
SE SE SE SE SE
74 84 84 91 99
25.5 25.0 26.6 21.1 25.8
AD AD AD AD AD
45.9 ...
SE-AD ...
87 ...
13.0 ...
AD ...
48.7 45.6 52.4
47.2 40.0 43.7
SE SE SE
97 88 83
23.5 17.7 20.7
AD AD AD
aSE ' broke at seam edge; AD * delaminated 1n the plane of the adhesive bond; SE-BRK = broke at either seam edge or 1n sheeting.
Source: Roberts et al, 1983.
-------
The field seam collected had a section that had not been properly
bonded. This appeared to be a "holiday" or section without adhesive. The
bonded section showed good shear strength at 87% of the breaking strength of
the material. This is higher than the factory seam shear strength for the
same sample; the test method, however, does not take the seam width into ac-
count. At 13.0 ppi, the peel strength of the field seam sample was approxi-
mately half the peel strength of the factory seam, which could be a result of
differences between factory and field seams or an indication of a loss in
properties. No information was available on the peel strength of the field
seams at the time of installation.
6.5.1.6.4 Conclusions—The results of testing the recovered PVC FML are
similar to those from laboratory and pilot-scale studies. Properties of the
PVC FML samples from the sludge lagoon vary considerably depending upon
sample location, and the condition of the samples reflects the degree to
which they are weather-exposed. However, neither the properties nor their
variability were unexpected in light of test values from previous laboratory
testing (Haxo, 1981; Haxo, 1982).
Exposure to the weather was the most significant degradation mechanism
to the FML. The sample on the north side (south facing) showed the most
severe effects. Samples of the FML under the sludge, which underwent
minimal or no exposure to the weather (saturated sludge and lagoon bottom
samples), showed normal properties for PVC FMLs. Samples exposed to the
weather showed evidence of shrinking and physical deterioration and had low
values for thickness, indicating a loss of plasticizer. The extractables
content of the exposed samples ranged from 18.9 to 30.5% depending on direc-
tional orientation. Since the amount normally compounded in PVC sheeting
ranges from 30-35%, these results clearly indicate that the weathered samples
have lost plasticizer.
After nine years of exposure under the waste, the samples on the lagoon
bottom had values comparable to unexposed 20-mil PVC sheetings, indicating
good retention of properties. Therefore, it appears that the type of sludge
being impounded did not affect the integrity of the PVC FML. However,
if a retained sample of the original sheeting had been available, these
results could have been expressed as changes in properties due to exposure or
percent retention of unexposed test values. Instead, data for the various
samples can only be compared with each other and with data for unexposed
20-mil PVC sheeting, as reported in the literature.
Factory seams in the installed FML maintained their integrity during
the long-term exposure; however, the field seams did not. All factory
seams tested in shear broke at the seam edge or broke in the sheeting out of
the seam area reflecting the strength of the FML. Some of the field seam
specimens tested in shear, however, delaminated in the plane of the seam
adhesive, as well as breaking at the seam edge. When tested in peel,
which is a more severe test, all of the test specimens for both types of
seams delaminated in the plane of the adhesive. The manner in which the
field seam test specimens broke in shear and the evidence of a "holiday"
6-41
-------
indicate an inadequate seaming operation and emphasize how critical field
seaming is to a successful lined impoundment and the importance of a rigorous
CQA program.
Mechanical puncturing, inadequate protection from exposure to the
weathe due to the sloughing of the protective cover, and poor field seaming
contributed to the deterioration and failure of the FML liner. In addition,
the sloughing of the protective soil cover indicated inadequate friction
between the soil and the FML for a slope of 2:1.
6.5.1.7 PVC FML from a MSW Landfill —
A sample of a 20-mil PVC FML, which had been in service for approxi-
mately six years, was removed in July 1984 from under 12 ft of MSW at a
Controlled Sanitary Landfill in Lycoming County, PA. The sample was obtained
from the lowest part of the landfill, i.e. in the sump area near the leachate
collection. Therefore, it can be assumed that the sample was in contact with
leachate for the entire six years. The FML was torn with a backhoe while
excavating a leachate pipe. At the time the sample was received by Matre-
con's laboratory the sample appeared to have completely dried out. The
unpleasant odor of the sample was similar to that of butyric acid. The
results of testing the exposed sample for analytical and physical properties
are presented in Table 6-19. Table 6-19 also includes data on the properties
of Matrecon FML No. 88, which is a 20-mil PVC received in 1976 from the same
manufacturer that produced the exposed FML. The formulation is reported to
be similar, if not the same as the exposed sample. This can be confirmed by
the almost identical analytical properties.
If data for Matrecon FML No. 88 are used as baseline values, then the
following changes in properties can be noted:
- Extractables = -5.1%.
- Tensile at break = -10.9%.
- Elongation at break = -7.6%.
- Stress at 100% elongation = -10.4%.
- Stress at 200% elongation = -10.4%.
- Tear resistance = -11.1%.
- Puncture resistance = +31.1%.
- Hardness = no change.
From these data, it can be concluded that the FML may have lost plasticizer
and that changes of about 10% have taken place in the physical and analytical
properties of the 20-mil PVC FML after six years of exposure as a liner in
an MSW landfill. Also, by the time of testing the samples had probably dried
6-42
-------
TABLE 6-19. PROPERTIES OF 20-MIL PVE FML EXPOSED AS MSW LANDFILL
LINER* COMPARED WITH AN UNEXPOSED 20-MIL PVC FML
Property
Analtyical Properties
Volatiles (105°C for 2 h), %
Extractables (2:1 CCl^CHsOH),
Ash, %
Specific gravity
Thermogravimetric analysis:
Ash, %
Char, %
Volatiles, %
Tonset
Physical properties
Thickness, mil
Tensile at break, psi
Elongation at break, %
Stress at 100% elongation, psi
Stress at 200% elongation, psi
Tear resistance, ppi
Puncture resistance
Thickness, mil
Force at puncture, Ib
Deformation at puncture, in.
Hardness, Durometer D
5-second reading
aMatrecon sample identification
Direction
of test
%
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
number E486; FML
Test
Exposed
FML E486
0.14
31.74
2.98
1.28
3.0
13.0
0.5
290°C
350°C
20
2950
2670
275
335
1700
1410
2360
1940
440
385
20.0
37.5
0.76
32
results
Unexposed
FML No. 88b
0.17
33.46
2.80
1.255
...
20.0
3395
2910
325
335
1870
1600
2600
2190
460
470
19.9
28.6
0.56
32
had been exposed for
six years.
^Liner No. 88 from Matrecon Database. Received in 1976.
6-43
-------
out and lost whatever moisture and volatile organics that ha.d been absorbed
when in service. The PVC FML remained flexible and useful with almost 90%
retention of all physical properties.
6.5.1.8 EPDM FML from Emergency Ponds for "Red Water"--
Samples of a 60-mil vulcanized EPDM flexible FML were recovered for
analysis and physical testing from different locations within a basin that
was being decommissioned after 18 years of service as an emergency pond for
"red water" (Haxo et al, 1987).
6.5.1.8.1 Description of the basin and the FML--The basin was con-
structed in late 1967 and early 1968 to act as a surge pond for "red water"
produced as a waste from TNT production. The pond covered an area of 3.1
acres and contained "red water" waste liquid, which was usually concentrated
by evaporation and then disposed of by incineration. It must be recognized
that the composition of the wastewater in the pond was highly variable
with time as the basin was used intermittently. The constituent concentra-
tion for selected analytes from a sample collected on May 28, 1981 is pre-
sented in Table 6-20.
The basin was last used during TNT production for the Viet Nam war and
was dismantled in May 1985, because it was no longer needed. The capacity of
the basin was 4.06 million gallons. It had an average depth of about 5 ft,
and the dike slope was 3:1. The FML was an unreinforced EPDM FML with
a nominal thickness of 60 mils. It was uncovered, that is, no soil cover was
placed on the FML. The water table in the area appeared to have been about
the same as that of the basin bottom as a partially-filled water drainage
ditch ran along the outside of the dike on the north and the east sides.
Most of the field seams along the basin slopes failed, but, from what
could be observed of the basin bottom, the field seams were mostly intact; we
did not observe a single failure of the factory seams.
The anchor trench along the berm top was completely inadequate for
anchoring the top of the FML. In combination with the failure of the field
seams, this poor anchorage resulted in large sections of the basin slopes not
being covered by the liner.
Gas generation below the FML resulted in the formation of "whales"
or areas of the liner which lifted off the floor of the basin. No means for
bleeding off the gas appeared to have been incorporated into the pond design,
e.g. an underdrain or gas-venting system. It was reported that these
"whales" were punctured to release trapped gases shortly before the sampling
was started. An attempt had been made earlier to relieve the trapped gases
by attaching vent pipes to the FML, but these vents appear to have been
ineffective.
6.5.1.8.2 Sampling of the FML--Four major samples were obtained and
were designated Samples A, B, C, and D. In addition, seven smaller samples
containing holes, apparently caused by rodents, were also collected.
6-44
-------
TABLE 6-20. COMPOSITION OF
SURFACE WATER SAMPLE3
Analyte
TNT-Related Organics Compounds
2,4,6-Trinitrotoluene (TNT)
2,6-Dinitrotoluene (DNT)
2,4-Dinitrotoluene (DNT)
2-Nitrotoluene
1,3, 5-Tri nitrobenzene
An ions
Nitrite
Nitrate
Sulfate
Phosphate
Heavy Ketals
Arsenic
Cadmium
Chromium (hexavalent)
Chromium (total)
Copper
Iron
Lead
Manganese
Mercury
Concentration
(yg/L)
<0.29
196.0
1.00
5.7
<2.2
<250
433,000
6,690,000
390
<13.0
8.8
1.5
125.0
141.0
5,360.0
40.2
195.0
<0.35
aSample number: SW109; sample date,
May 28, 1981.
Source: Tom Erdman of the Joliet Army
Ammunition Plant.
6-45
-------
The
below:
reasons for taking each of the major samples are discussed briefly
- Sample A was the major sample from this FKL. It was taken from the
northeastern dike (southern exposure) and extended from the anchor
trench at the top of the dike, down the dike, and on to the basin
bottom. A factory seam extended most of the sample length and a
field seam extended into the bottom section. Due to its size, the
strip was cut into three sections.
- Sample B included a field seam which was partly intact and partly
failed. It was taken from the northeastern dike between Sample A and
the northeast corner of the basin.
- Sample C was from the basin bottom. Before collection, it was
covered with very wet sludge and exposed to very wet mud on the
underside. A small strip cut from the liner adjacent to Sample
C was collected for volatiles determination.
- Sample D included a partly intact/partly failed field seam from a
"whale." Sample D was chosen because "whales" are considered to be
sites of stress on the FML and because of the presence of a field
seam.
The locations where the samples were collected are shown in Figure 6-5, a
simplified drawing based on the "as-built" drawing of the basin.
RODENT HOLES 1 AND
RODENT HOLES 3,4 AND 5>
SAMPLE
\ A
FLUME
Top of Dike
10' Typical
SAMPLE
B
Figure 6-5. Schematic drawing of the basin showing the locations
where the FML samples were collected.
6-46
-------
No retained sample of the original liner was available for use as a
baseline reference. The top portion of Sample A, which was buried in the
shallow anchor trench on top of the dike, probably had only a modest exposure
to either waste or sun, but it appeared to have aged and lost extractables
and thus could not be used as a baseline reference.
6.5.1.8.3 Testing of FML samples—The FML samples were photographed and
measured at the laboratory; Sample A, the "strip" sample, was tested in the
following areas:
- The upper section of the "strip", was tested in four areas which had
been exposed in the anchor trench, at the top of the slope, at
mid-slope, and at the toe of the slope, respectively.
- A second section was tested for analytical and physical properties in
an area that had been at the bottom of the slope.
- A third section, which had been exposed at the bottom of the basin,
was tested for physical properties.
The other three samples were tested as follows:
- Sample B, taken at a field seam, was tested in two areas designated
Samples Bl and B2 which correspond to two different layers of the
same sheeting. Sample Bl was exposed to the weather and possibly
waste; Sample B2 was the underflap part of the intact portion of the
field seam.
- The strip taken adjacent to Sample C from the bottom of the basin was
analyzed for volatiles immediately upon receipt at the laboratory.
Physical tests and additional analyses were later performed on the
main portion of Sample C.
- Sample D, cut from a "whale", was tested for analytical and physical
properties and the intact part of the seam was tested in the peel
mode.
The results of the testing are presented in Table 6-21. The results of
testing an unexposed EPDM manufactured in 1972 are also included for com-
parative purposes (see Section 6.4.1.8.5).
6.5.1.8.4 Inspection and testing of the seams--The seams in the FML
were prepared both in the controlled environment of the factory and in the
uncontrolled outdoor environment of the field. Roll stock of EPDM sheeting
was manufactured and fabricated at the factory into large panels that were
then installed in the basin. Vulcanized seams were made to join the sheeting
into panels at the factory, while vulcanizable adhesives were used to join
the panels to form the liner in the field.
6-47
-------
TABLE 6-21. PROPERTIES OF 60-MIL EPDM FML SAMPLES COLLECTED FROM THE EMERGENCY "RED-WATER" BASIN
CTi
I
00
Strip Sample A
Property
Analytical properties
Volatile;, %
Extractablesd, %
Ash, I
Specific gravity
Physical properties
Tensile at break, psi
Elongation at break, %
Stress at 100% elongation, psi
Stress at 200% elongation, psi
Tear resistance, pp1
Puncture resistance
Thickness, mil
Maximum force at puncture, Ib
Deformation at break, in.
Maximum force, normalized for
100-mil thickness, Ib
Hardness, Duro A points
1 -second reading
5-second reading
Direction
of test
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Prelim-
inary
Sample9
0.88
15.9
...
...
1870
...
375
...
515
...
1150
...
193
...
62.5
76.2
1.20
122.0
70
67
Anchor
trench
Al-1
...
13.52
7.90
1.218
1865
1860
370
410
640
600
1230
1140
190
185
...
...
...
...
69
66
Top of
slope
Al-2
1.19
14.65
• • •
...
1810
1775
280
290
790
725
1480
1390
160
150
55.6
67.4
1.09
121.2
72
70
Mid-
slope
Al-3
1.35
16.31
...
...
1825
1765
330
355
640
545
1290
1180
160
165
55.0
53.0
1.07
96.4
68
66
Toe of
slope
Al-4
0.94
16.56
...
...
1835
1755
355
370
605
525
1260
1130
170
165
53.7
51.8
1.06
96.5
67
64
Basin
ATI
0.56C
21 .60e
7.3
...
1750
1735
415
455
445
390
1000
890
190
180
56.5
54.0
1.17
95.6
64
63
bottom
S3k6"
• • •
21.28
...
1.181
1765
1725
400
410
450
400
1015
935
170
170
63.0
58.5
1.21
92.9
65
63
FML on slope
with field seam
Top Bottom
layer layer
Bl B2
0.77
14.26
...
...
1925
1765
275
265
800
700
1555
1425
155
150
69.7
89.0
1.00
127.7
71
67
0.72
17.13
7.90
1.203
1765
1730
345
350
505
460
1150
1090
170
170
71.3
79.0
1.14
110.8
65
61
Basin
bottom
C
0.77C
21.62
7.24
1.180
1755
1730
390
420
445
380
1045
925
175
175
61.5
62.7
1.31
102.0
63
61
Top of
"Whale"
D
0.85
17.72
8.04
1.183
1815
1805
370
400
525
465
1165
1040
180
180
56.5
56.6
1.15
100.2
69
66
1972
EPDM
linerb
0.38
23.41
6.78
1.173
1635
1550
520
500
350
320
800
740
206
211
60
56.9
1.46
94.8
...
57
aPreliminary sample received 1-5-84. Direction of test uncertain but is believed to be the machine direction; sample taken from top of slope by Mr.
T. Erdman of the Joliet Army Ammunition Plant.
t>Baseline reference—FML No. 8 (Haxo et al, 1985).
cValues of 0.83% and 1.23% were obtained, respectively, on small samples of A2-5 and C that had been collected and sealed in small tins to prevent loss
of volatiles.
dExtractables were determined with methyl ethyl ketone.
of 22.28% was obtained on the small sample of A2-5 collected for volatiles determination.
-------
The vulcanized factory seams appeared, after exposure to "red water" and
weather, to have maintained their initial properties. The factory seam was
3.2 in. wide, and the edges of both the top and bottom sheets were beveled to
a thickness of about 30 mils up to 0.75 inches in from the edge of each
sheet.
The field seam was 6 in. wide and was bonded with a vulcanizable ad-
hesive. A low temperature vulcanizable tape was placed along the edge of the
top sheet. In addition to its function in bonding the sheets together, the
tape also served to round the edge of the top sheet. However, the tape along
and adjacent to the edge of the top sheet opened in many of the field seams.
This opening may have been caused by differential shrink and swell of
the sheeting and the adhesive.
Many of the areas tested for physical properties included factory or
field seams that were tested for seam strength in shear and peel modes. The
location and type of seam samples that were tested and the results of the
testing are presented in Table 6-22.
Seam strength in shear mode was measured in accordance with ASTM D882
and D3083, modified for testing exposed FMLs. Testing in peel mode was
performed in accordance with ASTM D413 in 90° peel. In both modes of test-
ing, 1-in. wide strip specimens were tested at a jaw separation rate of
2 inches per minute.
6.5.1.8.5 Selection of a baseline reference—No retained sample of the
FML was available that could be used as a baseline reference. The samples
that were recovered from the basin were 18 years of age; consequently, there
was a question as to whether any of these samples was suitable for use as a
baseline reference. However, data were available on EPDM FMLs that had been
produced in 1972 and tested in earlier work performed by Matrecon for the EPA
on a study of liners for municipal solid waste landfills (Haxo et al, 1982;
Haxo et al, 1985). A review of the analytical results for an FML produced in
1972 indicated that it was essentially the same as that of the liner in-
stalled in the basin in 1967. A comparison of analytical properties of the
1972 EPDM liner with the liner recovered from the basin is given in Table
6-23. The data as a group constitute a fingerprint of the liner, such as is
described by Haxo (1983) and in Section 4.2.2.6.
The physical properties for the 1972 membrane are presented in Table
6-21. Tensile strength, stress at 100% elongation, and puncture resistance
are comparable to the data obtained on the liner taken from the basin,
assuming somewhat higher extractables content. Using these data, one has a
baseline reference against which to compare the effects of the exposure on
the liner samples recovered from the basin.
6.5.1.8.6 Results and discussion—Data on the samples taken from the
various sections of the "strip" sample can be used to assess the effect of
6-49
-------
TABLE 6-22. SEAM STRENGTH IN SHEAR AND PEEL MODES OF 60-MIL EPDM SEAM SAMPLES
COLLECTED FROM THE EMERGENCY "RED-WATER" BASIN
i
01
o
Strip Sample A (type of seam)
Anchor Top Mid-
trench slope slope
Al-1 Al-2 Al-3
Seam test (Factory) (Factory) (Factory)
Seam strength in shear3
Maximum strength^, ppi
Strength at break, ppi
Locus of break0
FTBd
Non-FTBd
Seam strength in peel6
Maximum strength, ppi
Locus of break0
FTBd
Non-FTBd
3ASTM D882/D3083, modified;
64 .0 65 .6
64.0 65.6
0 0
5 AD 5 AD
11.7 6.5 7.8
000
5 AD 5 AD 5 AD
Lower On basin
slope bottom
Al-4 A2-5 A3-6
High on On basin Top of
slope bottom "Whale"
B1/B2 C D
(Factory) (Field) (Factory) (Field) (Field) (Factory) (Field)
68.1 69.2
68.1 69.2
1 SE 0
4 AD 5 AD
8.2 9.2 10.1 8.8
00 00
5 AD 5 AD 5 AD 5 AD
five specimens tested per sample, except where otherwise noted.
slipped in the clamps during testing; results declared
Maximum value corresponds
cLocus-of-break determined
Locus of Break
CL
SE
BRK
AD
to tensile strength at break
from the following code:
Description
Break at clamp edge
Break at seam edge
Break in sheeting
Delamination in plane
void.
for all specimens tested.
Classification
FTBd
FTBd
FTBd
non-FTB<*
64.4
64.4
0
3 AD
17.6
0
5 AD
Two specimens
* • • • • •
• • • • • •
• • • • • •
• • • • * *
8.7 8.9
0 0
5 AD 5 AD
of Sample B2
of adhesive bond
Number preceding code indicates the number of test specimens that broke in the manner indicated by that code.
dFTB - Film-tear bond.
eASTM D413 modified using 1-in. wide specimens which were tested in 90° peel at 2 ipm; five were specimens tested per
sample except where noted otherwise.
-------
TABLE 6-23. COMPARSION OF ANALYTICAL PROPERTIES
OF EXPOSED SAMPLE AND BASELINE REFERENCE
Analysis
Extractables3, %
Thermogravimetric analysis:
Polymer + oils, %
Polymer (calculated)13, %
Oil (from extractables), %
Carbon black, %
Ash, %
Total
Ash, %
Specific gravity
Joliet
Sample C
21.62
57.2
35.6
21.6
35.2
7.6
100.0
7.24
1.183
1972 FML
No. 8
23.41
57.4
34.1
23.4
35.0
7.5
100.0
6.78
1.173
aExtractables consist of oils + extractable curatives
and antidegradants (determined with methyl ethyl
ketone).
bCalculated by subtracting the extractables from the
thermogravimetric analysis (TGA) determination for
polymer + oil.
the different exposures from the top to the bottom of the basin. Some of the
basic conclusions that can be drawn are:
- The extractables decrease with increasing distance from the bottom of
the basin which has been under "red water" or sludge.
- The sheeting on the top part of the slope, which was exposed to the
sun, contains about one-third less of oily plasticizer than was in
the sheeting on the floor of the basin. The latter sheeting has
the highest extractables values. These high values approximated
that of the "baseline reference" (i.e. the 1972 EPDM FML). Also,
tensile strength, modulus (stress at 100% elongation), and puncture
resistance values tend to increase with decreasing extractables, that
is, with distance up from the bottom of the basin, as is shown in
Figures 6-6 through 6-8. On the other hand, the elongation at break
decreases as the extractables decrease during the exposure, as shown
in Figure 6-9.
6-51
-------
1900
(0
o.
CO
Q>
CO
JU
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Figure 6-6. Tensile at break of the samples of exposed FMLs as a
function of their extractables. Tensile data are the
averages of the values obtained in both machine and
transverse directions. The samples with the low values
for extractables were cut from the liner at the top of
the slope. Those with the high values were cut from the
liner on the bottom. R = Baseline Reference EPDM,
produced in 1972.
CO 0)
900
800
700
col 60°
« co 500
£ o 400
300
24 22 20 18 16
Extractables, %
14
12
Figure 6-7. Stress at 100% elongation (S-100) of the samples of
exposed FMLs as a function of their extractables. S-100
data are the averages of the values obtained in both
machine and transverse directions. The samples with the
low values for extractables were cut from the liner at
the top of the slope. Those with the high values were
cut from the liner on the bottom. R = Baseline Reference
EPDM, produced in 1972.
6-52
-------
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- In the case of sheeting protected at the seams by an upper layer of
sheeting, the extractables are greater and the tensile strength,
modulus, and puncture resistance are less than those of the upper
layer. These differences again appear to reflect the higher extrac-
tion content of the protected sheeting.
- The factory seam results tend to show increased strength values in
both shear and peel modes with increased distance from top to bottom
down the slope. The peel adhesion values increased from 6.5 to 10.1
ppi with distance down from the anchor trench; all the failures in the
tests were adhesion failures between the sheetings.
- In the case of field seams, there is a difference between the ex-
posure locations. A high value of 17.6 was obtained on an unfailed
part of the seam that was high on the slope. This seam had partially
failed during exposure. Testing was performed on an unfailed portion
of the seam. In this case, the adhesive appeared to have cross!inked
more than had the seams in the other locations. In all cases, the
preponderant failure was a cohesive failure in the adhesive.
6.5.1.9 PVC FML from an Industrial Landflll--
A 30-mil PVC liner was installed in an industrial landfill in Dover
Township, New Jersey in 1981. The liner was in use until 1985 at which
time the liner was damaged by heavy equipment during a cleanup to remove
drums containing liquid organics. Samples of the liner were taken at that
time by the New Jersey Department of Enviromental Protection and submitted to
Matrecon for testing.
Industrial wastewater-treatment sludge and drummed chemical waste
from the manufacture of dyes and plastics were stored in the landfill.
Excavation of the site revealed that many of the drums were badly corroded
and some had leaked. The NJDEP reported that toluene, methylene chloride,
and ethyl benzene were present in the sludge and drummed waste stored at the
facility.
The exposed PVC FML appeared to have stiffened substantially during the
four years of exposure in the landfill; this was attributed to loss of
plasticizers from the PVC compound. The losses of extractables were somewhat
erratic in magnitude, but they generally resulted in lower tensile strength
and elongation at break and higher values for stress at 100% elongation
tear strength, and specific gravity. Headspace gas chromatography (GC) of
the exposed FML samples did not detect the presence of any of the organic
solvents (toluene, methylene chloride, and ethyl benzene) reported to
have been stored in the landfill. These solvents had probably been absorbed
by the FML during service and then volatilized during excavation, transpor-
tation, and storage. The headspace GC analysis demonstrated how easily these
solvents volatilize, as well as the difficulty of measuring their effects on
an exposed liner.
6-54
-------
Factory seams were made by dielectric-welding, and the field seams
were made with a solvent-cement. The results of the peel testing indicated
that the exposure of the liner may have affected the dielectric-weld of the
seams. Field seams were not available to test.
6.5.2 Field Studies Conducted by Giroud
Under EPA Contract No. 68-03-1772, Giroud (1984a) reported on 29 case
histories of FMLs with varying degrees of detail and data. Eight case
studies were chosen for review since they represent a variety of end-uses,
materials, and examples of different problems or successes.
Giroud's Case Study 2 is the only one of the 29 reported that provides
actual data based on testing of the exposed FMLs. The results of plasticizer
loss and change in physical properties over time for a PVC liner are pre-
sented. Also discussed are the effects of sun exposure and position on the
slope (above or below liquid level) of the liner.
Table 6-24 summarizes the case histories discussed in this section.
6.5.2.1 CSPE FML from Evaporation Pond at a Chemical Plant
(Giroud, 1984a - Case 1) —
In March 1981, a 129,000 ft2 evaporation pond was constructed in a
Middle Eastern county at a chemical plant. The pond was lined with a 40-mil
CSPE FML reinforced with polyester scrim. Based on tear specification values
of 20 Ibs, the reinforcing fabric probably was an 8 x 8 - 250 denier rein-
forcing scrim. The FML was placed directly on compacted soil on the pond
bottom and on a nonwoven needle-punched polyester geotextile on the slopes.
The slopes were 2 to 1. The factory and field seams were made using a hot
wedge.
The pond remained empty for seven months before being filled. Normal
operations consisted of placing liquids that contained acids and salts in the
pond and allowing them to evaporate. Eleven months after the first filling,
massive failure occurred. Apparently, during the time the pond was empty,
animals damaged the FML causing several small holes. Holes were also caused
by defective seams, damage to the FML during transportation, and damage
during installation. Because the soil beneath the FML was sensitive to acid,
cavities developed as acid leaked through the liner. Increased stresses
caused seams to give way and the pond emptied rapidly.
The exposed CSPE was difficult to weld and thus to repair. Therefore,
the FML was replaced, and the site design was changed to include several
single-lined smaller ponds and one large one with a double liner and a geonet
LCRS between the liners.
6.5.2.2 PVC FML from a Mining Operation - Uranium Tailings
(Giroud, 1984a - Case 2; Giroud, 1984b) —
Nine large evaporation ponds (Ponds 1 through 9) with a total area of
approximately 7 million square feet were built and lined with a PVC FML
6-55
-------
TABLE 6-24. SUMMARY OF CASE STUDIES BY GIROUD
171
Liner type
30-mil CSPE, reinforced
20-mll PVC for bottoms;
40-mil PVC for slopes
20-mll PVC;
40-mil PVC
160-mil, reinforced
asphalt membrane
40-mil PVC, oil-
resistant
40-mil butyl rubber,
unreinforced
Type of waste
Acids and salts
Uranium tailings,
salts, sulfuric
add (pH 1.5 to
2.0), traces of
kerosene
Uranium tailings
Potable water
Brine solution:
150 to 310 g/L
of NaCl; traces
of hydrocarbons
Industrial water
storage
Type of Case Years of
Impoundment Location number exposure
Chemical plant A Middle Eastern 1 2
Country
Mining operation Sahara Desert 2 2 to 5
(nine ponds)
Mining operation Sahara Desert 3 2
(nine ponds)
Reservoir Southeastern France 4 5
Salt plant Southeastern France 6 7
Chemical plant I sere, France 8 10
Comments on FML
Puncture holes caused
by animals: acid
sensitive soil formed
cavities.
Erosion of slopes
through wave action;
seam failures from
defective seams and
excessive stresses;
mechanical damage;
aging of exposed PVC.
Improved design as
a result of Case 2,
resulted in a
successful instal-
lation.
Defective seaming,
del ami nation and
puncturing of
membrane
Exposed PVC stif-
fened, shrunk, and
seams opened
No problems; success
has been reported to
be the result of
careful design and
installation.
60-mil butyl rubber,
reinforced
20-mil PVC in bottom;
36-mil CPE (reinforced)
on slopes
Potable water Reservoir
Municipal waste- Wastewater
water
Washington, U.S.A. 11 3 to 9 Shrinkage of the
FML resulted in
opened seams.
Western U.S.A. 26 4 Blisters in rein-
forced CPE; seam
failure; degradation
of reinforced CPE
at the water line.
Source: Giroud, 1984a.
-------
between 1987 and 1981. The ponds were constructed for a mining company
located in the Sahara Desert region, and were intended to contain uranium
tailings with sulfuric acid. The composition of the contained liquid was as
follows:
- Salts (magnesium sodium sulfate, iron, alumina) = 100 g L~l.
- Sulfuric acid (pH = 1.5 to 2.0) = 10 to 15 g L'1.
- Traces of kerosene = up to 1 L m~3.
- Traces of nitric acid = up to 0.1 g L~l.
Four smaller reservoirs lined with PVC FMLs were also constructed for storing
water or acid. All ponds were in operation from 2 to 6 years.
A 20-mil PVC was used as the FML for the bottom of the ponds and a
40-mil PVC for the side walls which had a slope of 2 to 1. A geotextile was
placed underneath the FML on the side slopes. The PVC FML was installed
without an earthen protective cover. The factory and field seams were made
using a hot wedge. A cross section of a typical dike for the ponds is
presented in Figure 6-10.
Various problems were observed in the design of the pond; in addition,
properties of the PVC FML were studied to evaluate the effects of service.
Severe tears caused by shrinkage were observed on exposed slopes.
6.5.2.2.1 Problems—Pond 1; Due to wave action and liquid overtopping
the crest of the dikes, much erosion occurred on the slopes. In one area,
the anchor trench had eroded to the point that the FML had pulled out of the
trench. Large quantities of liquid got behind the liner and caused more
instability of the slopes and more of the FML to pull out of the trench.
Repairs were made and the corner of the pond was reconstructed.
Pond 2: A seam opened, allowing liquid to leak into the subsoil. The
problem was alleged to be caused by defective seaming, excessive stresses
as the result of wave action, and shrinkage of the FML caused by aging.
Pond 5: A raft had broken loose and punctured several holes in the
liner. Piping of the underneath soil occurred and the FML burst in areas not
supported by the soil.
Pond 7: A factory fabricated seam had opened up and the same situation,
as noted in Pond 2, had occurred.
It was noted in all ponds that the FMLs were under tension at many
locations and was off the supporting soil (bridging) by as much as 1 ft over
concave parts of the pond. This phenomenon was alleged to be caused by loss
of plasticizer in the PVC FML due to excessive heat on the exposed membrane.
This was confirmed by analysis of the various samples described below.
6-57
-------
Gas Draining Pipes
[Diameter - 80 mm (3 in.)]
Anchor Trench
Silty Clayey Sand
(20 in. thick)
CT1
I
cn
OD
Dike Core
Geotextile
PVC FML
(40 mils thick)
-.
te-'^*&^Zi
Silty Clayey Sand
(Thickness varying from 10 in. to 40 in.)
PVC FML
(20 mils thick)
Figure 6-10.
Typical cross section of the dikes for the uranium tailings ponds —
Ponds 1-9 (not to scale). (Based on Giroud, 1984a).
-------
6.5.2.2.2 Samples and testing — Approximately 40 samples were removed
from the nine large ponds containing acid and 4 smaller reservoirs containing
acid and water and tested to determine the effects of exposure.
The plasticizer contents of the samples were compared with the plasti-
cizer content of a control sample. The plasticizer contents were determined
by extracting the plasticizer with a mixture of carbon tetrachloride and
methyl alcohol. Plasticizer losses were calculated using plasticizer content
value expressed as parts of plasticizer per 100 parts of resin. The results
of measuring the plasticizer contents of samples exposed on the berms are
presented in Figure 6-11 as a function of exposure time.
70
60
-- 50
5
o
O 40
_n>
O_
30
g 20
o
10
• 1 mm (40 mil) thick
o 0.5 mm (20 mil) thick
oW
oW
W = Water Reservoir
9 « Empty Pond 9
Other» Ponds 1 - 8
10 20 30 40 50
Time After Installation, months
60
Figure 6-11.
Plasticizer loss as a function of time for samples permanently
exposed.
The analyses also indicated loss of the stearate stabilizer as a func-
tion of time; values did not indicate any degradation of the PVC resin
(Giroud, 1984b).
Twelve samples were taken from different locations in Pond 5 from the
anchor trench down the slope to the floor of the pond, as is shown in Figure
6-12, to assess the effects of exposure at different depths. The plasticizer
losses, as a function of location on the slope are shown in Figure 6-13.
The tensile properties of the FML samples were determined. Values of
elongation at break as a function of plasticizer loss are shown in Figure
6-14.
6-59
-------
(a) Cross Section of Dike for Pond 5
_1_
4.0m (13.1 ft)
12 16 20 24
Time, months
.7m (10.8 ft)
28 32 36
(b) Level of Liquid in Pond 5 as a Function of Time
Figure 6-12.
Study of the influence of immersion on aging; (a) cross section
of dike of Pond 5 showing locations, indicated by letters,
where samples were taken; (b) level of liquid in Pond 5 as a
function of time. (Based on Giroud, 1984a and 1984b).
-------
110
TO 100
o>
m
TO
.0
TO
O>
c
o
Hi
BO
60
40
.o
I 20
cc
Figure 6-14.
0 10 20 30 40 50 60
Loss of Plasticizer, %
Retention of elongation at break as a function of the plas-
ticizer loss. (Based on Giroud, 1984a and 1984b).
6.5.2.2.3 Discussion of results—The action of sun-generated heat with
time was the main factor governing aging of the PVC FML. Acceleration of
plasticizer loss by exposure to acid spray (at water line and at ore pads)
was also observed, but results indicate exposure to acid alone was not as
severe as exposure to direct sunlight over time. The study concludes that
monitoring plasticizer loss can be used to evaluate the aging of a PVC FML,
and elongation at break can be used to evaluate the consequences of plasti-
cizer loss because it is directly related to the flexibility of the FML.
6.5.2.3 PVC FML for a Mining Operation—Uranium Tailings
(Giroud, 1984a - Case 3) —
This is the same site as Case 2. The results of studying the existing
evaporation ponds and reservoirs, which are summarized in the previous
section, were incorporated in the design of this pond (Pond 10). The fol-
lowing changes were made in the basic design:
- The side slopes at 4:1 were less steep.
- An earthen protective cover was placed on top of the entire PVC FML.
- The PVC FML was extended to cover the crest of the dikes.
- The height of liquid was restricted to control the action of high
waves.
- Geotextile was placed under the entire FML.
6-61
-------
Figure 6-15 shows a typical cross section of the dike design used in con-
structing Pond 10.
Samples of the FML are being taken periodically for laboratory testing
to determine plasticizer loss and change in physical properties. After two
years the performance of the lining system had been satisfactory.
6.5.2.4 Asphaltic FML in a Potable Water Reservoir
(Giroud, 1984a - Case 4) —
In October 1979, 237,000 ft2 of a 160-mil reinforced asphaltic FML was
used to line a potable water reservoir in the southeastern part of France.
The slope of the pond was 2.5 to 1, and no cover was provided for the FML. A
geotextile and a drainage collection system, consisting of three different
types of pipes placed in trenches, were installed underneath the liner. All
seaming was done in the field using hot air. Unusual weather conditions
resulted in defective seaming because the installer/contractor installed in
the rain.
Eighty opened seams were discovered a few days after the reservoir was
partially filled the first time. Many rocks had fallen from surrounding
mountains and punctured the uncovered FML. Delamination occurred where
the asphaltic liner was less than 40 mils in thickness.
Erosion occurred in "selected material" of some of the subgrade and
puncture of the liner resulted caused by sharp rocks from below.
Most of the problems were due to a rush in schedule which led to poor
design and poor construction.
6.5.2.5 PVC-OR FML in Salt Ponds (Giroud, 1984a - Case 6) —
Two ponds at a salt plant in the southeastern part of France, approxi-
mately 35,000 ft2 each in size, were lined with a 40-mil unreinforced
PVC-OR FML. The liquid was a brine solution with a sodium chloride content
of 150 to 310 g L"1 and traces of hydrocarbons. The FML was exposed with
no earthen cover. The sides slopes were 3 to 1. A geotextile and an asphal-
tic liner were installed under the FML. A single collection trench was
constructed on top of the PVC FML across the bottom of each pond.
Due to plasticizer loss caused by sun exposure, the PVC-OR FML had
shrunk and lifted off its support at the foot of the slope in several places
resulting in accumulated tensions which caused the seams to peel open (Figure
6-16). Excessive flaps at the seam areas also resulted in seams peeling
open. It was reported that during quick emptying of the ponds, pressure
resulted and propagated peeling apart of the seams. Figure 6-17 depicts
these phenomena.
6-62
-------
Wave Protection Rock Layer
(Thickness-18 in.)
Geotextile
Earth Cover Material
40-mil PVC FML
Geotextile
OJ
Silty Clayey Sand
(Thickness - 30 in.)
Road Base Layer
(Minimum Thickness - 20 In.)
Silty Clayey Sand
(Thickness - 20 in.)
Sand
(Thickness - 20 in.
y/vfyw.y/Ax
Compacted Silty Clayey Sand Trench
(Depth - 40 in.)
Connection Between 20-mil
DETAIL A
and 40-mil FMLs
20-mil PVC FML
Geotextile
Silty Clayey Sand
Earth Cover Material
t- PVC FML
Geotextiles
Figure 6-15. Typical cross section of the dike for a uranium-tailings pond--Pond 10 (not
to scale). (Based on Giroud 1984a).
-------
PVC-OR FML
fmxxxooooomwx^^
Geotextile
Asphaltic Liner
V/-CWA"
NOT TO SCALE
Figure 6-16.
Schematic showing FML with a seam being lifted off its support.
This phenomenon is known as "bridging". Excessive stresses can
result in delamination of the seam. (Based on Giroud, 1984a).
6.5.2.6 Butyl Rubber in Industrial Storage Ponds (Giroud,
1984a - Case 8)~
In 1974, one of the first double-liner systems, approximately 100,000
ft2 in area, was installed at a chemical plant in Isere, France, for storage
of industrial water. The design of the system from top to bottom consisted
of:
- A 40-mil unreinforced butyl rubber FML.
- A needle-punched nonwoven polyester geotextile.
- An aggregate layer.
- A reinforced asphaltic FML.
- Natural soil.
The slope of the side walls was 2 to 1, and there was a drain between the two
liners. The asphaltic FML was sprayed in place onto a needle-punched non-
woven polyester geotextile. The butyl rubber FML had both factory and field
vulcanized seams. The field seams were vulcanized in place using a special
seaming machine. In this seaming process a bead of nonvulcanized chlorobutyl
was placed between the two sheets to be seamed, and heat and pressure were
applied for approximately 2 minutes. All seams were carefully inspected.
This site was studied in 1984 and no problems were reported. The pond
had been in constant operation for 10 years. The success is reported to be a
result of careful design and installation.
6-64
-------
(a) Mechanism of FML seam opening caused by
unbalanced liquid pressure during rapid drawdown
(b) FML seam placed over support irregularity
(c) FML seam placed over edge of collection
trench walls
Figure 6-17.
Schematic showing stresses on seams with excessive flaps,
(Based on Giroud, 1984a).
6-65
-------
6.5.2.7 Butyl Rubber FML in Potable Water Reservoir
(Giroud, 1984a - Case 11)--
In March 1966, an old cracked concrete potable-water reservoir in the
State of Washington, approximately 54,000 sq ft in size, was relined with a
60-mil butyl rubber FML reinforced with a 22 x 14, 210 denier x 420 denier
nylon scrim. The liner was not protected by a soild cover, and the slopes
were 1.5 to 1. Factory seams were made by a vulcanization process. Field
seams were made using a 4-in. wide lap joint, an ambient temperature self-
vulcanizing butyl rubber cement, and a 30-mil butyl gum tape. A 2.5-in. wide
gum tape was placed over the exposed seam edge as a cap strip. As an ex-
perienced installation contractor provided his own crew, the skill level of
the installation personnel is assumed to have been high. The weather was
reportedly excellent throughout the installation.
The butyl rubber FML failed in 1969 after 3 years of service when
both factory and field seams above the water level began splitting from
substantial shrinkage of the nylon-reinforced butyl rubber sheet. (The
shrinkage can be attributed primarily to the nylon reinforcing fabric which
tends to shrink when heated, such as occurs in the sunlight). Some repairs
were made as the seams split. However, the liner was removed and replaced
with a 6-in. reinforced concrete liner in 1975 because of the excessive
maintenance required.
6.5.2.8 PVC and CPE FMLs in a Wastewater Impoundment
(Giroud, 1984a - Case 26)--
The slopes of two municipal wastewater impoundments in the western part
of the United States were lined with a 36-mil fabric-reinforced CPE FML in
October 1980. The bottom of one pond was lined with a 20-mil unreinforced
PVC with an earthen cover, while the bottom of the other pond was lined with
bentonite. Approximately 150,000 sq ft of the reinforced CPE was required to
cover the slopes of each pond. Several dozen blisters appeared in the FML
during and shortly after installation. Most of the blisters were in the
seam area. Several seams perpendicular to the slope opened; it was necessary
to lower the level of the wastewater to perform repairs. The appearance of
the opened seams indicated that the primary cause of failure was due to
improper seaming. In some cases, severe wave action resulted in water
extending over the crest of the dike onto the roadway. This caused weakening
and sloughing of the side slope resulting in the opening of other seams due
to excessive stresses.
A catastrophic failure occurred along the waterline on one entire side
of one of the ponds (approximately 1,000 feet). Apparently, an algae mat
would develop at certain times of the year when the waterline was lowered.
As the algae dried out on the surface of FML, the top layer of the laminated
reinforced CPE split open, allowing water into the fabric layer when the
water level was raised. After several repeated cycles of this phenomenon,
the FML was completely delaminated and split open in a 12-in. wide area along
the entire slope on one side; no remedial measures were taken as litigation
is pending.
6-66
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6.5.3 Field Studies Conducted by Ghassemi
Nine hazardous waste surface impoundment facilities were reviewed and
assessed by Ghassemi et al (1984). These facilities represent a range of
industries, waste types, environmental settings, types of FMs, and designs.
Five of the case studies are reported in this section because they are
examples of FML successes and/or failures. These studies are summarized in
Table 6-25.
6.5.3.1 ELPO FML in Ponds Containing Electrolytic Metal Process
Liquor (Ghassemi et al, 1984 - Case Study No. 1) —
Two surface impoundments were lined with 20-mil ELPO in 1972 and 1979
to serve an electrolytic metal refining plant located in a semiarid to desert
area of the southwest. The waste contained was described as an aqueous
acidic waste (pH typically less than 2) resulting from a process liquor and
sludge which had a high heavy metals content. The size of the ponds were
16,000 ft2 and 48,000 ft2, respectively. The smaller pond was originally
lined with a 20-mil ELPO in 1972. The FML deteriorated along the slopes by
cracking and brittleness attributed to weathering. The FML of the smaller
pond was replaced with a 30-mil reinforced CSPE FML in 1981. No deterio-
ration problems have been reported in the larger pond; however, it had been
in operation only four years when this survey was conducted.
6.5.3.2 PVC and CPE FMLs in Wastewater and Rinse Water
Ponds (Ghassemi et al, 1984 - Case Study No. 2)--
Two FKL-lined surface impoundments were constructed to serve a pesti-
cide formulation and packaging facility located in a alluvial valley of the
southwestern part of United States with a dry summer subtropical climate.
The washdown pond, placed in service in 1979, was lined with two layers of
20-mil unreinforced PVC with a leak-detection systems. This pond contained
wastewater originating from the washdown of pesticide formulation-packaging
areas and application equipment. The size of the pond is approximately
2,000 ft2, and the bottom of the pond is underlain by 1 ft of gravel and a
30-mil unreinforced PVC FML, which is on the bottom of the pond only. The
second pond was a rinsewater pond, approximately 7,500 ft2 in size, lined
with a 20-mil unreinforced CPE FML under which a 1-ft layer of sand and
a 10-mil unreinforced PVC-OR FML had been installed. The pond was intended
to contain steam cleaning and vehicle washdown wastewater. Leak-detection
systems for both ponds consisted of a collection pipe embedded in the granu-
lar drainage layer between the FMLs. These pipes were connected to separate
monitoring stations. After several years of service the owner installed a
0.25-in. layer of fiberglass over each pond liner to give added protection
and a better surface for cleaning.
At the time of the survey, no problems had been noted by the operator or
the State regarding the liner systems in both ponds.
6-67
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TABLE 6-25. SUWART OF CASE STUDIES OF FMLS BY GHASSEMI
CT>
I
CTl
oo
Liner type
20-mil elasticized
polyolefln, replaced
with 30-mil rein-
forced CSPE
20-mil PVC double-
lined; 20-mil CPE
plus double-lined
30-mil reinforced
EPOM on slopes;
12-mil PVC on
bottom
50-mil EPDM
30-mil PVC on
bottom; 30-mil
reinforced
CSPE on slopes
Type
of waste
Aqueous acidic;
pH <2; plus
heavy metals
Washdown and
rinses of pro-
cess equipment
Various inor-
ganic and or-
ganic chemi-
cals; pH 1 .3 to
1.9; TDS 20,000
to 42,000 mg/L
High inorganic
nitrogen fluc-
tuating pH
50% solids,
0.5% sulfuric
acid; 0.25%
organics
(kerosene);
pH 1.8 to 2.5
Type of i^raundnent
Electrolytic aetal
refining plant
Pesticide foraulation
Fertilizer manufactur-
ing coifi lex
Equalization basins
for chevical plant
UraniuB tailings
pond
Location
Southwestern
United States
Southwestern
United States
Southwestern
United States
Mid-Atlantic
Coast, United
States
Northwestern
plains state,
U.S.A.
Case
study Years of
number exposure Comments on FML
1 9 Cracking and brittleness
from weathering
2 4 No problems
4 6 "Hhale" formation caused
by contact of waste
water with calcium car-
bonate clay soil; me-
chanical damage
8 5 Swelling and chemical
attack; seam failure
9 3 Seam failure in CSPE;
punctures, abrasion,
and mechanical damage
in both
Source: Ghassemi et al, 1984.
-------
6.5.3.3 EPDM and PVC FMLs in Evaporation and Cooling Ponds
(Ghassemi et al, 1984 - Case Study No. 4)~
A fertilizer manufacturing complex situated in the southwestern part
of the United States had two FML-lined evaporation and cooling ponds.
The side walls, which had a slope of 3 to 1, were lined with a 30-mil
polyester-reinforced EPDM FML; the bottoms were lined with a 12-mil un-
reinforced PVC. Approximately 1.6 million ft2 of PVC and 300,000 ft2 of
EPDM were used. Major wastewater constituents found in both ponds included
ammonia, organic nitrogen, nitrate, sulfate, chlorides, algicides, oil and
grease, surfactants, polymers, and various metals. The pH of the wastewater
ranged from 1.3 to 1.9, and the total dissolved solids (TDS) ranged from
20,000 to 42,000 mg L'l.
"Whales" developed in the FML apparently because the acid waste had
reacted with the calcium carbonate clay soil under the FML resulting in the
generation of gases. The source of the leaks was not described. Attempts
were made to release the trapped gases by partially draining the ponds,
forcing the gas into one area, placing sandbags around the "whale", then
placing a valve in the FML to release the trapped gas. Extensive parts of
the PVC FML in each pond were replaced. The ponds continued to have leakage
problems as of 1982.
The EPDM FML on the side slopes appeared to hold up better than the
PVC, but also exhibited tears and open spots mostly resulting from mechani-
cal damage.
6.5.3.4 EPDM FMLs in Wastewater Ponds (Ghassemi et al, 1984 -
Case Study No. 8)--
Two equalization/diversion basins at a chemical plant located in the
mid-Atlantic Coast region were lined with a 50-mil EPDM in late 1976. The
raw wastewater discharge is characteristically high in organic nitrogen
content and had a widely fluctuating pH. The EPDM Uner was selected after
liner-waste compatibility tests were conducted by the company's corporate
engineering group. The liner was exposed with no protective soil cover.
When the FML was inspected in 1981 to determine the cause of its
failure, there was strong evidence that there had been a lack of adequate
QA/QC during construction and that some deviations from the design specifi-
cation had gone undetected. The failure of the FML was manifest as exten-
sive swelling and seam separation. In the presence of the particular
organics encountered in the waste, EPDM apparently is subject to swelling,
especially at the air-waste interface. This problem was not detected during
the liner-waste compatibility tests which preceded the liner material
selection. The seam separation at and below the water line resulted from a
deterioration of the adhesives used, as well as the inadequate overlapping
of the sheetings.
6.5.3.5 CSPE and PVC FMLs in Uranium Tailings Pond
(Ghassemi et al, 1984 - Case Study No. 9) —
In August 1980, an FML-lined uranium tailings pond was completed to
handle wastes from a uranium mining and milling operation in a northwestern
6-69
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plains state. The waste was 50% solids with the aqueous phase containing
0.5% by weight sulfuric acid, 0.25% by weight (kerosene) and had a pH of 1.8
to 2.5. The size of the pond was 3,100 ft by 3,500 ft (approximately 11
million ft^). The pond was lined with a 30-mil unreinforced PVC FML on the
bottom and a 30-mil polyester-reinforced CSPE FML on the side slopes.
Since installation, there have been four instances of documented failure
of the liner:
- Four months after installation, a CSPE to CSPE field seam separated
for a distance of 300 feet; poor seaming technique in cold weather
was said to have caused the problem.
- Several puncture holes (about 50) were noted and patched. These
holes were reportedly due to an uneven subgrade surface and mechanical
damage.
- A 6-in. hole had abraded through the liner caused by a leak in a
discharge pipe.
- Holes and punctures caused by floating debris and wave action.
Immediate corrective actions were taken involving patching of the holes and
seams and continuous removal of debris from the pond area. The last inspec-
tion recorded was in 1983, with the pond still in service.
6.5.4 Performance of PVC FMLs as Canal Linings
Morrison and Starbuck (1984) studied the performance of buried FMLs,
primarily 0.25-mm (10-mil) PVC, used to control seepage from Bureau of
Reclamation irrigation canals in Montana, Wyoming, New Mexico, and Nebraska
(see also Morrison, 1984). Samples were recovered from canal installations
after service for 1 to 19 years and tested. The FMLs in all cases were
buried under soil covers which were specified to have a thickness of 250 mm
(10 in.) plus 25 mm (1 in.) for each 0.3 meter of water depth.
Results of the study indicate that PVC FML linings are providing
satisfactory service for seepage control in canals and are viable alterna-
tives in areas not suitable for concrete or compacted earth linings. Results
of the study also indicate that some stiffening of PVC and loss of elonga-
tion occurred with time. This stiffening and loss of elongation is caused by
the loss of plasticizer used in the PVC compound to impart flexibility.
Percent losses ranged from about 12% for 9 years of exposure to 46% for 19
years of exposure. In addition, small holes and tears were noted in most of
the recovered samples, all of which had a thickness of 10 mils.
The performance of the PVC FMLs was primarily dependent on three
factors:
- Source--Linings originally manufactured with a high plasticizer
exhibited less aging.
6-70
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- Location of exposure in canal—Samples obtained from within the water
prism exhibited less aging than those obtained outside the prism.
- Subgrade condition—FNLs placed over smooth subgrade performed better
than those placed on a coarser base.
As a result of this study, the Bureau of Reclamation is specifying
0.5-mm (20-mil) PVC FMLs for lining canals rather than 0.25-mm (10-mil)
sheeting and recommending a minimum cover depth of 400 mm (16 in.) to protect
the FMLs from animal traffic and cleaning operations.
6.5.5 Analysis of a Survey of FML-Lined Haste Containment Units
Data from a survey of lined containment units were reviewed and analyzed
by Bass et al (1985) to determine the factors which contributed to either the
success or failure of the liner at these facilities. Under a subcontract,
five experts from companies in the liner industry provided information on
lined facilities with which thay had been associated. Each expert was asked
to select between 4 and 7 sites and to include both "successes" and "fail-
ures" within that group. In order to encourage maximum disclosure of in-
formation, especially where "failure" was involved, the identities of the
experts and the individual sites have been held confidential. Essentially
all of the information provided by these experts was in the form of responses
to a questionnaire for each site, which included supporting drawings, design
specifications, etc. and a summary report. Altogether, data on 27 contain-
ment units were collected. Most of the units selected by the experts were
surface impoundments; not all were considered hazardous waste containment
units.
The units that were studied varied in geographic location, size, age,
in the type of wastes that had been handled, and the type of lining system.
Most of the sites (approximately 20) were lined with only a single FML. Some
of the sites had both an FML and a layer of compacted clay, with or without a
drainage layer between the liners. One site had a triple FML system. FMLs
were used in 25 of the 27 units. At one site bentonite was applied at a rate
of 25 tons per acre and mixed to a depth of 4 inches. At another site an
asphaltic-concrete liner was used. Top layers of soil cement were used at
two sites, and a sprayed-on liner FML based on a urethane-modified asphalt
was used at another site.
Based on the definitions used in this study, the 27 units selected by
the experts included 12 "failures" at 10 sites. At four or five of these
sites groundwater contamination apparently resulted from the failures.
For the purpose of this study, a "failure" in the pre-operational period
was defined as a condition of the installed lining system which required
nonroutine corrective measures to make it suitable for planned operations. A
failure during operations was defined as any condition of the lining system
which caused (or threatened to cause) groundwater contamination, or otherwise
caused operations to cease because of observed abnormalities.
6-71
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The nature of the "failures" noted included chemical attack of the liner
(1 or 2 sites), physical tears or punctures (5 sites), problems with field
seaming or other liner installation activities (1 to 3 sites), and large gas
bubbles, also referred to as "whales", under the FML (1 site).
A summary description of the failures at case study sites is presented
in Table 6-26. The abbreviations used for the different types of FMLs and
the number of sites lined with a particular FML type for which information is
available are as follows:
Number
Abbreviation Polymer type of sites
DMA Urethane-modified asphalt 1
CPE Chlorinated polyethylene 5
(OR = Oil-resistant)
HOPE High-density polyethylene 7
CSPE Chlorosulfonated polyethylene 6
PO Polyolefin 1
PVC Polyvinyl chloride 9
The suffix (R) after the FML abbreviations in Table 6-26 indicates that
the FML is fabric-reinforced. HOPE and PVC liners are usually unreinforced,
while CSPE and, to a lesser extent, CPE are usually fabric-reinforced.
In their analysis to identify the causes of the FML failures, Bass et al
(1985) recognized not only the immediately-preceding action (e.g. subsoil gas
generation in a high water table area leading to "whales"), but prior fail-
ures that might be associated with poor design, lack of quality control, or
communication failures between companies. They recognized that even failures
such as these may be preceded by philosophical or conceptual failures wherein
misconceptions or lack of concern about liner systems are a root cause of the
subsequent failure. This type of analysis thus recognizes a hierarchy of
failure modes with one type of failure potentially leading to another until
some ultimate failure (i.e. a breach in the liner) occurs.
Some of the contributing factors, if not causes, for the failures noted
by Bass et al (1985) include the following:
- Failure to control operations (at an operating site) so as to safe-
guard the liner.
- Poor (or inadequate) design work in general.
- Failure to use a qualified design engineer.
- Poor (or inadequate) installation work in general.
6-72
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TABLE 6-26. SUMMARY DESCRIPTION OF "FAILURES" AT CASE STUDY SITES
Site ID
Nature of "failure"
How detected
Apparent cause
Other contributing factors
CTi
CO
Vl-2 CSPER (S) Five holes found in liner
caused by owner-operating
personnel; minor brine loss
V2-1 CSPER (S) Chemical attack of liner at
liquid surface
V2-2 CSPER (S) "Whales"
V2-3 CSPE (S) Liner ripped
V3-1 PO-R (S) a) Holes and tears in
liner
b) Escape of dredge
material
c) Tear in liner panel
V3-2 PVC (S)
Chemical pollutants showed
up in drain water col-
lected below liner
Monitoring Carelessness by owner-
well operating personnel
Visual Attack or dissolution by
oil-based defoamer
Visual Gas generation under liner;
no allowance made for gas
venting in design
Visual Tank truck slipped down
slope
Visual Liner placed between
layers of coarse rock
Visual Liner placed over coarse
rock
Visual Waves entered construction
area and scraped liner
against dike
Leak Apparent blockage of leach-
monitor ate collection drain;
backup of leachate
Lack of clear operating procedures.
Possible lack of concern (speculative).
Use of oil-based defoamer not anti-
cipated, thus not in original program.
Inadequate control of operations.
Inadequate study of soils and hydro-
geology at site; presence of organic
matter (in soil) had, however, been
noted.
Site used before for disposal of organic
sludge.
No fence around site.
Liner exposed.
Poor design.
Poor control of operations.
Poor communication among contractor,
installer, and engineer.
Job awarded to low bidder (speculative).
Poor design (subgrade too coarse).
Poor control during installation.
Wet and windy weather.
Poor bonding at seams, appurtenance (?).
Poor control of installation practices;
used "Honor Camp" youth to install FML.
Undersized collection drain (?); due to
poor design (?).
Continued . .
-------
TABLE 6-26. (CONTINUED)
Site ID
Nature of "failure"
How detected
Apparent cause
Other contributing factors
V3-4
V5-1
V5-2
Bentonite
(S)
CPE/UMA0
(3D,IS)
CPE/PVC
(S)
V5-4 PVC (D)
Pollutants showed up in moni-
toring wells around site
Liquids found in leak
detector
Physical damage to liner
prior to being put into
service
Fluid intrusion into
monitoring well
Monitoring Unknown; possible break-
well up of soil sealant
liner
Leak Probable failure of sealing
detector of concrete joints with
PVC strips and spray-on
UHA
Visual Unknown, but suspect
carelessness
Monitoring Membrane rupture at five,
well uniformly- spaced posi-
tions; tears probably by
D-4 cat tractor used to
spread soil cover over
liner
Unknown; possible failure to fully test
soil sealant for this type of appli-
cation.
Process for selecting liner unclear.
No way to physically test liner once in
use.
Concrete installer, against explicit in-
structions, used curing compound that
inhibited proper bonding of UMAb to
concrete.
Poor design; improper information supplied
on UMAD; owner suggested use of UMAb.
Poor installation; lack of knowledgeable
supervision.
Questionable cooperation between con-
tractors.
Job awarded to low bidder (speculative).
High winds and cold temperatures during
construction (took 11 months).
Operator of tractor let soil cover get
too thin.
Poor control of installation.
aS = Single liner; D = Double liner.
bUrethane-modified asphalt membrane.
Source: Bass et al, 1985, pp 27-28.
-------
- Poor or inadequate communication and cooperation between companies
working on an installation job.
- Using untrained and/or poorly supervised installers.
- Failure to conduct (or adequately conduct) waste-liner compatibility
tests.
- Adverse weather conditions during installation.
- Using an old dump site, with contaminated soil, as a site for a
1ined unit.
- Using processes for selecting a lining material and an installation
contractor that did not help ensure that good materials and workman-
ship would result.
- Selecting a liner material by a process not involving detailed bid
specifications; specifications should be prepared by a design engi-
neer, and not by an FML manufacturer.
- The age of the unit; more failures were associated with the older
units.
Success was defined in this study as the converse of failure, i.e.
non-routine corrective measures were not required, and the liner system was
not breached. Bass et al (1985) considered the two main factors that con-
tributed to success at a lined containment unit to be:
- A proper philosophical and conceptual approach.
- The extensive use of quality assurance programs in all facets and
stages of a unit's construction and operation.
Key elements of this approach are:
- Assuming that there will be problems.
- Examining the possible consequences of those problems.
- Taking appropriate steps (e.g. design changes, quality control
plans) to avoid or minimize the problems.
Success is also more likely to result if the general approach described
above is applied to all stages or facets of a liner system including design,
material and contractor selection, site preparation, liner installation,
unit operation, and closure. Within each of these areas, the generalized
approach needs to be applied within the framework of a formal quality as-
surance program. It is worth noting that at least 23 of the 27 sites in this
study had some form of a quality assurance program for one or more critical
operations (primarily liner manufacture, fabrication, and installation),
6-75
-------
although the quality of these programs could not be assessed from the data
submitted by the experts.
Other factors that Bass et al (1985) noted as contributing to success
included:
- Overdesign of system.
- Presence of a knowledgeable customer.
- Bidding to specifications.
- Selecting qualified companies for construction, installation, and FML
manufacture.
- Cooperation among companies during construction and installation.
- Conducting waste-liner compatibility tests.
- Simplicity of design.
- Good weather at time of construction and installation of the FML.
6.6. FIELD STUDIES OF CEOTEXTILES
Two field studies of geotextiles were reported by Christopher (1982);
even though neither of the geotextiles studied was exposed in surface
impoundments or landfills, these studies do provide information on geo-
textiles that were in service for 10 years. The two studies are summarized
in the following subsections.
6.6.1 Field Study No. 1
The first field study inspected the condition of a geotextile used
in the 79th Street Causeway in Miami Beach, Florida. The causeway was
constructed using a monofilament woven polypropylene geotextile as a reverse
filter in a stone riprap revetment-type seawall to protect one of the bridge
abutments and a section of the causeway. In this design, the geotextile
replaced a conventional granular filter as a means of preventing erosion of
subgrade soils through the riprap. The protected section was designed for
3-ft waves and a 3-ft tidal variation.
When the project was inspected in October, 1979, the seawall appeared to
have been functioning as designed, as no erosion problems were observed.
Other areas of the causeway were also inspected where erosion control systems
other than geotextiles were in use. In one area, concrete with very little
aggregate had been poured against the abutment and over the exposed soil.
Large voids were present (up to 1 ft 1n diameter) both in the concrete mat
and underneath the mat where the soil and concrete had eroded. Inspection of
6-76
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other areas Indicated that using riprap without a filter layer (e.g. a
geotextlle) did not prevent areas from washing out, and that the minimum
amount of erosion control was not successful.
Four areas along the length of the seawall with the geotextlle filter
were selected for further examination of the soil-geotextlle system.
Site 1 was selected due to the smaller size of riprap covering, Its location
in relation to protection of the bridge abutment, and its relatively flat
slope. Site 2 was selected because 1t appeared to be exposed to more direct
wave action than the other areas of the causeway. Site 3 was selected in an
area where the fabric had been improperly placed and exposed to the sun.
Excavation of the fourth site indicated that no geotextHe had been placed.
At Site 1 the fabric appeared to be in excellent condition, and no
large tears or punctures were observed. Small perforations and punctures
(two to three 0.1-0.25-in. diameter holes per sq ft) were present which
probably resulted from the placement of the riprap during construction. At
Site 2 only one small tear was noted in the fabric, and the same magnitude
and size of small perforations that were encountered at Site 1 were present.
At Site 3 observations of the fabric indicated several tears and punctures
where the fabric was exposed.
Samples of the geotextile were tested in the laboratory for strength,
permeability, and particle retention. Grab strength was determined in
accordance with ASTM D1682. Permeability of the geotextile specimens was
determined using a U-tube geotextile permeameter, which is presented sche-
matically in Figure 6-18. A falling head technique, from a head of 10 cm
to a head of 3.7 cm, was used. (Note: since this testing was performed, ASTM
has developed D4491-85, which is the preferred method). The particle reten-
tion of the fabric was evaluated in accordance with the Corps of Engineers,
Army Engineers Waterways Experiment Station AD-745-085 procedure for deter-
mining the "open" area of the geotextile.
Grab strength results are summarized in Table 6-27. The grab strength
of the sample from Site 2, where there was more wave action, was 30% less
than that of the Site 1 sample. Figure 6-19, which was developed for Site 1,
relates strength variations to location along the slope. In general, the
grab strength appears to increase with location in the downslope direction.
Section 4 of the Site 1 sample, which was probably under water during most of
its 10-year service, had the greatest strength.
The results of determining the permeability and particle retention of
the fabric are presented in Table 6-28. A slight reduction in the permea-
bility of the excavated geotextile in comparison with the unexposed geo-
textile was found. Percent of open area is defined as the area of the
openings (multlpled by 100) divided by the total surface area of the unit of
fabric and 1s equivalent to the porosity of soil. The net results Indicate a
decrease of less than 10% 1n open area of the fabric.
The study Indicated that the geotextlle showed good long-term stability
during exposure and retained a significant amount of strength after ten years
6-77
-------
of service. There are some indications that the strength of the fabric may
be affected by cyclic wetting and drying or repeated loading from wave
action.
Water Inlet
Overflow Level
Cover Plate
'1'
1
Lucite Chamber
(2-in. I.D.)
• Geotextile
Slip Couple
(2-in. I.D.)
Compression Ring
Screw Down Clamp
Slip Couple
Figure 6-18. Geotextile permeameter. (Based on
Christopher, 1982).
6.6.2 Field Study No. 2
The second study reviewed the condition of a geotextile which was
of the same type that was studied in the previous case study (Section 6.6.1).
6-78
-------
The monofilament polypropylene geotextile was used in the construction of the
abutments for the Bahia Honda Bridge in Florida as a protective filter
beneath sand-cement riprap constructed abutment slopes, drains, and seawalls.
In this system, the fabric acted as a filter between the erosion control
armoring and the underlying soil to prevent loss of soil through cracks or
holes in the riprap as a result of weathering or wave action.
TABLE 6-27. GRAB STRENGTH OF A MONOFILAMENT WOVEN POLYPROPYLENE
GEOTEXTILE THAT HAD BEEN IN SERVICE FOR 10 YEARS
Test in weaker principal
Sample
New:
Sample 1
Sample 2
Site 1:
Section 1
Section 2
Section 3
Section 4
Site 2
Site 3
Strength,
kg
97
101
89
96
100
96
67
51
Apparent
elongation at
failure, %
50
43
37
40
40
37
38
25
direction
Retention
of original
strength3,
• * •
89
96
100
96
67
51
Test in stronger principal direction
Strength,
kg
171
163
130
144
136
161
104
111
Apparent
elongation
at failure,
30
35
38
38
39
38
25
47
Retention
of original
strength0
...
76
84
80
95
61
65
aOriginal grab tensile strength = 100 kg used to calculate retention values.
^Original grab tensile strength = 170 kg used to calculate retention values.
Source: Christopher, 1982.
A site investigation indicated good long-term stability of the sand-
cement constructed facilities after 10 years of service. No erosion problems
were apparent at any of the drains, slopes, or seawalls protected by the
sand-cement armoring system, which indicated that the installation was
functioning as designed. Geotextile could be seen in protruding from beneath
the riprap at the edge of the structures in several sections of the abut-
ments, drains and seawall. In all cases, the geotextile appeared to be in
good condition.
Samples of the exposed geotextile were collected and tested for
strength, permeability, and the particle retention in accordance with the
same test procedures used in the first field study. The grab strength of
the exposed geotextile was 167 kg in the stronger principal direction and
111 kg in the weaker principal direction. These results indicate good
retention of strength in both directions, the values for which were 170 kg
and 100 kg, respectively, for new fabric. The apparent elongation at failure
of the exposed sample was approximately 10% greater than the elongation at
failure of the unexposed geotextile. The sample from between the sand bags
had an average permeability of 1.2 x 10"^ cm s~l, and the sample from
directly beneath the sand bags had a permeability of 5.7 x 10~3 cm s~l
indicating a loss in permeability. (The permeability of geotextile when new
ranged from 3 to 4 x 10~2 cm s~l. The sample from between the sand bags
6-79
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200
100
in
JO
S
O
•—cr
O Weaker Direction
• Stronger Direction
369
Distance Down Slope (ft)
12
Figure 6-19. Strength of fabric versus position on slope at Site
1. (Based on Christopher, 1982).
TABLE 6-28. PROPERTIES OF A MONOFILAMENT WOVEN POLYPROPYLENE
GEOTEXTILE THAT HAD BEEN IN SERVICE FOR 10 YEARS
Sample
New
Site 1:
Section
Section
Section
Section
Site 2
Permeabil ity,
cm s~l
1
2
3
4
3 to
?
2
1
1
2
4
.6
.2
.8
.9
.3
x
x
X
X
X
X
10-2
10-2
10-2
10-2
10-2
10-2
Open
area, %
5
5
5
4
5
5
6
.5
.7
.4
.8
.0
.1
Openings
containing
particles, %
20 (
44
40
19
• • *
29
.5)3
29
(44)a
to
(35 to
48
42)a
Open area
completely
closed, %
...
6
6
6
9
8 to 10
aWashed with 3-ft head of water.
Source: Christopher, 1982.
6-80
-------
had less than 10% of the openings closed by sand particles; however, the
sample from beneath the sand bags had up to 50% of the space closed by sand
particles. It appears that the large amount of clogging found in the sample
from beneath the sand bags resulted from construction of the armoring
system.
6.7 FIELD STUDIES OF LEACHATE COLLECTION AND REMOVAL SYSTEMS
Leachate collection and removal systems (LCRSs) must maintain flow
capacity over the expected service life and post-closure care period of the
containment unit in order to function either as a system for controlling
liquid head on a liner or as a leak detection, collection, and removal
system.
Clogging of LCRSs that has have resulted in significant loss of drain-
age and collection capacity has been observed. Some examples of clogging
mechanisms include:
- Calcium carbonate encrustation.
- Iron deposition.
- Formation of biological slimes.
- Physical mechanisms.
Calcium carbonate encrustation occurs by a mechanism similar to that
seen in the natural formation of stalactites.
Iron oxide deposition can occur from a number of complex processes; they
can restrict leachate flow by clogging the inside of pipes or causing ce-
mentation or clogging of the materials surrounding the pipes.
The formation of biological slimes can occur when slime-producing
bacteria or organisms are present under favorable conditions. In general,
the formation of biological slimes is dependent on the presence of bacteria
together with the appropriate nutrients, presence of oxygen, growth condi-
tions and energy sources.
Examples of physical mechanisms for clogging include collapse of a
system due to excessive loading of the waste above, damage to the system
related to construction of the lining system (e.g. compaction of an overlying
soil layer), and mechanical intrusion into the drainage layer by the layers
above and/or below when under a static load, including intrusion by soils,
FMLs, and/or geotextiles. Collapse of a pipe in the drainage system can
result in a localized subsidence, which in time can cause a breach in an
overlying FML and ultimately cause failure of the unit.
Ramke (1987), in an investigation of the construction and maintenance
of granular-based LCRSs, reported examples of damage to these systems in MSW
landfills. Of the seven he described, the drainage material of five were
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clogged by encrustation. This damage resulted in the build up of as much
as 33 ft of liquid on a liner. Flushing, dissolving, and grinding were
partially successful in most cases in repairing the damage. In the other two
LCRSs, the damage was mechanical due to improper selection of pipe and
inadequate dimensioning of the collection pipes which collapsed.
Ramke (1987) concluded that damages have occurred repeatedly in LCRSs
and pipelines in MSW landfills due to encrustation. Repair measures were
only partly successful. Analyses of the encrustations showed that iron and
calcium were the major components. The causes were considered to be bio-
chemical and physical-chemically controlled precipitation processes.
Bass (1986) discussed the results of interviewing 16 individuals in 1983
from companies that design, construct, operate, and/or regulate landfills
equipped with LCRSs. The objective of the survey was to determine various
types of failure mechanisms that might occur in an LCRS. The experience with
these systems is summarized in Table 6-29.
No detailed study was available on the field performance of LCRSs
designed with synthetic drainage media.
6.8 OBSERVATIONS AND LIMITED CONCLUSIONS FROM STUDIES OF THE
IN-SERVICE PERFORMANCE OF FMLS AND ANCILLARY MATERIALS
IN CONTAINMENT APPLICATIONS
6.8.1 Introduction
The information that is reported in this chapter on in-service perfor-
mance of materials and containment units is basically of the following two
types:
- Quantitative information on the effects of various exposures on the
properties of FMLs obtained by sampling and testing specific materi-
als that had been in service in containment units.
- Qualitative information from the experience and field observations of
experts relating to the condition of the containment units as a
whole. Much of this information is descriptive and was not obtained
in a uniform manner by the different experts for the various case
studies, nor were the purpose and scope of the inspections the
same.
The reader should be aware of the limitations of the information presented in
this chapter and of the generalities that can be derived and applied to liner
systems being installed in containment units. These limitations include the
following:
- The objectives of the studies varied with the observer and reporter
and, therefore, cannot be considered a statistically valid sample of
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TABLE 6-29. EXPERIENCE WITH LEACHATE COLLECTION AND REMOVAL SYSTEMS
Failure mechanism
Sedimentation
Sedimentation
Sedimentation
Sedimentation
Sedimentation
Sedimentation
Biological growth
Biological growth
Biological growth
Biological growth
Chemical precipitation
Chemical precipitation
Chemical precipitation
Biochemical precipitation
Pipe breakage
Pipe breakage
Pipe separation
Pipe deterioration
Pipe deterioration
Tank failure
Capacity exceeded
Capacity exceeded
Outlet inadequate
Facility
type
NS°
NS
Co-disopsal
Co-disposal
Municipal
NS
Industrial
Municipal
Municipal
Co-disposal
Municipal
Co-disposal
Co-disposal
Co-disposal
NS
Municipal
Municipal
NS
Hazardous
Co-disposal
Co-disposal
Hazardous
Co-disposal
Cause9
C
U
U
U
U
C
D
U
U
U
0
U
0
U
0
D
C
D
0
D
D
0
0
Comments
No filter installed
General experience
In 1-year old system
Of gravel layer and pipe
General experience
General experience
100-ft long biological
growth flushed out under
high pressure
Reduction in flow every
2 years; flushed out
Of filter fabric
On 0.75-in. stone, not
clogged
EPA test cell, not
clogged
Iron oxide, not clogged
Attributed to waste
characteristics
In leachate collection
wells
By clean-out equipment
if bends greater than
22°, general experience
Differential settling,
improper bedding
Joints not glued
Problems with ABS pipe,
general experience
From acid or solvent
disposed of in wrong
cell
Leachate holding tank
Under-design, other
problems noted
Periodic rather than
automatic pumping of
sump
Caused leachate buildup
aO = operation related; D
U = undetermined.
DNS = not specified.
Source: Bass (1986)
design related; C « construction related;
6-83
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all in-place liner systems; also, there is likely to be some dispro-
portionate representation of key variables.
- The types of units and the types of wastes that were contained
at these units varied widely. The types of liquids or wastes that
were contained included municipal and industrial wastewaters, oil
field brines, municipal solid waste, power plant ash, and water being
conveyed for irrigation, in addition to hazardous chemical wastes.
- The amount of information for each study is highly variable due to
limitations on the amount and the quality of the information made
available to the observer and/or the reporter and to the time avail-
able for performing each field study or survey.
Any conclusions drawn from the information presented in this chapter need to
be consistent with these limitations.
The observations and limited conclusions regarding in-service perfor-
mance of materials are made first on the performance of individual components
of a containment unit. These include the liner system, the leachate col-
lection and removal system, and the supporting structures and earthworks.
Factors that contribute to the success or failure of a containment unit are
the correlation of field performance and laboratory assessment of FMLs and
the need for in-service performance information on waste containment units
are also discussed.
6.8.2Performance of Components
6.8.2.1 Liner System--
Except for FMLs that are sentive to ultraviolet light and plasticizer
loss and are exposed without a protective soil cover on the berms and slopes
of surface impoundments, there is little indication from the field studies of
polymeric deterioration during exposure. The PVC FMLs have shown the great-
est need to be protected. Without protection by a soil cover, plasticized
FML compositions exhibited loss of plasticizer, shrinkage, and loss of
elongation, resulting in brittleness and breaches in the liner. On the other
hand, buried PVC FMLs have shown relatively good retention of properties and
have successfully controlled seepage from irrigation canals for up to 19
years (Morrison and Starbuck, 1984).
Incompatibility of the FML with the waste was observed in several cases.
Incompatibility was indicated by the opening of seams, the swelling of the
FML, delamination of fabric-reinforced FMLs, and the loss in values of some
properties such as tensile strength, elongation at break, tear strength, and
puncture resistance, all of which are properties of importance in the per-
formance of FMLs. In a major fraction of these cases, the swelling was a
result of uncontrolled chemicals being placed in the containment unit.
Increasing permeability of FMLs was not observed in any of the field
investigations, which is indicated by the relatively low swelling of the
recovered samples. On the other hand, neither the composition nor the
6-84
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concentration of the volatile constituents immediately below an FML appear to
have been determined. Increased permeation would be indicated by high
swelling of the FML. Thus, what chemical incompatibility was observed did
not appear to affect the FML's permeability.
Chemical incompatibility does not appear to have been a primary factor
in the formation of breaches in the FML except in causing the opening of
seams; however, it probably has a secondary influence on the FMLs, causing
changes in their properties such as lower modulus, lower mechanical proper-
ties, such as tensile strength, tear resistance, and an increased tendency
toward creep. In all of these cases, the FML would have to be under a
tensile or torque stress to result in a breach.
In the results there was no indication that biodegradation of the
polymers had taken place, except for the possible loss of plasticizer
when the FML was buried (Morrison and Starbuck, 1984). Biocides are pre-
sently being incorporated in PVC FMLs to reduce this effect. On the other
hand, there was an observation of bacterial effects on the surface of FMLs by
algae formation followed by subsequent drying which caused the top coating of
a fabric-reinforced FML to crack (Giroud 1984a, Case 26).
Failure of the seams was reported in several instances due to in-
adequate seaming, quality control, and improper selection of the FML for the
particular application. For example, a butyl rubber reinforced with nylon
was exposed without a cover (Giroud, 1984a, Case 11). The FML tended to
shrink due to shrinkage of the nylon when heated (e.g. by sunlight), and the
seams were pulled open.
Many of the breaches that have been observed in FMLs appear to be
related to improper design and/or inadequate construction and quality control
of other components of the containment unit.
6.8.2.2 Leachate Collection and Removal Systems--
The various materials that are involved in an LCRS include drainage
soils and gravels, geotextiles, geonets, geocomposites, and pipe. The
observations that were reported on these materials are very limited. Two
sets of observations on LCRSs were those of Ramke (1987) and Bass (1986).
In these cases, clogging of LCRSs was observed as a function of biological
growth and inorganic deposits and carbonates and higher minerals. Pipe
failures due to inadequate dimensioning, to overburden pressure, or perhaps
to damage during construction were also observed. There were no indications
in any of the cases of actual chemical incompatibility of the pipe with the
leachate.
6.8.2.3 Supporting Structures and Earthworks--
Several cases were reported where the soil on which a surface impound-
ment was placed was incompatible with the waste liquid being contained;
for example, problems resulted from the leakage of acidic waste liquid into
underlying soil that contained carbonates. In one case, leakage of the waste
6-85
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liquid resulted in gases being generated underneath the FML and the formation
of "whales" which eventually caused failure of the FML (Ghassemi et al, 1984,
Case Study 4). In another case, the acidic waste caused formation of cavi-
ties below the FML resulting in eventual failure of the FML (Giroud, 1984a,
Case Study 1).
In another case, the wave action against a slope caused sloughing and
formation of cavities behind an FML, which resulted in failure of the FML
(Giroud, 1984a, Case Study 2).
6.8.3 Correlation of Field Performance and Laboratory
Assessment of FMLs
Overall liner-waste compatibility observed in the field indicated by the
effects on the properties of the FMLs in contact with waste streams appeared
to compare well with laboratory results obtained with similar waste streams.
It would thus appear possible to predict through compatibility tests the
effects of the contained liquid on the properties of FMLs, at least for
short-term service. Also, the weatherability of FMLs in-service was predict-
able from laboratory tests.
Whereas the laboratory studies and in-service performance related to the
effects of weathering and swelling can be correlated, the field studies
indicated that many problems resulting in physical damage to FMLs in surface
impoundments have not been simulated in laboratory or pilot-scale tests.
Examples of these include:
- "Whale" formation (trapped gas beneath the FML).
- Seam failures resulting from various stresses in the seam (e.g.
shrinkage, and stresses caused by subsidence).
- Erosion of slopes from wave action and sloughing of the protective
cover.
- Puncture and mechanical damage from operations.
These types of damage can be related to inadequate design, construction,
and/or management during the operations of the containment unit.
Another phenomenon that was observed in a field study and had not been
predicted in laboratory or simulated-service-type testing is the damage that
can occur to some liners exposed to wastewaters that can sustain algae
growth. A CPE FML was severely affected at the water line of a municipal
wastewater storage facility. The top ply of the CPE FML split and delami-
nated as a result of algae drying out on its surface (Giroud 1984a - Case
Study 26).
6-86
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6.8.4 Factors That Affect the Performance of a Containment Unit
Based on the information presented in this chapter, it would appear that
poor performance of containment units can be attributed to factors such as
the following:
- Lack of good project planning during design and construction phases.
- Failure to execute proper quality assurance/quality control (QA/QC).
- Deviations from original and/or desired liner specifications.
- Inadequate liner-waste compatibility testing.
- Lack of rigorous site-specific investigations to develop the proper
basis for design and construction.
The information presented in this chapter also indicates that four
factors appear important for a successful FML installation:
- Selection of qualified companies for design, manufacturing,
fabrication, installation, and quality control.
- Proper design including evaluating needs for chemical compatibility
testing, selection of materials and specifications, and strict
adherence to specifications.
- Quality control, quality assurance, and good communications during all
phases of construction and installation.
- Controlling operations at the site during the service life of
the facility.
6.8.5 Need for In-Service Performance Information
on Haste Containment Units
Much of the information contained in this chapter relates to materials
that are no longer being used in waste containment. Little information is
available on the performance of polyethylene FKLs and the other geosynthetics
that are presently used in the construction of liner systems and LCRSs. In
addition, most of the field studies describe single-lined units that would
not adequately meet the RCRA requirements for hazardous waste containment
units. Over and above the monitoring programs required by regulation, it is
highly desirable to assess the performance of the materials of construction
used in constructing containment units from the time they are designed
through post-closure monitoring in order to assess the type and magnitude of
changes in properties of the construction materials. Only in this way
can a correlation be established between properties and performance which can
then be used to develop criteria for predicting chemical compatibility and
6-87
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long-term serviceability of an FML and other geosynthetics with a particular
leachate or waste liquid.
6.9 REFERENCES
ASTM. Annual Book of ASTM Standards. Issued annually in several parts.
American Society for Testing and Materials, Philadelphia, PA:
D297-81. "Methods for Rubber Products—Chemical Analysis," Section
09.01.
D412-83. "Test Methods for Rubber Properties in Tension," Sections
08.01, 09.01, 09.02.
D413-82. "Test Methods for Rubber Property—Adhesion to Flexible
Substrate," Section 09.01.
D624-86. "Test Method for Rubber Property—Tear Resistance," Section
09.01.
D638-84. "Test Method for Tensile Properties of Plastics," Section
08.01.
0792-66(1979). "Test Methods for Specific Gravity and Density of
Plastics of Displacement," Section 08.01.
D882-83. "Test Method for Tensile Properties of Thin Plastic Sheet-
ing," Section 08.01.
01004-66(1981). "Test Method for Initial Tear Resistance of Plastic
Film and Sheeting," Section 08.01.
01682-64(1985). "Test Methods for Breaking Load and Elongation of
Textile Fabrics," Section 07.01.
D2240-86. "Test Method for Rubber Property—Durometer Hardness,"
Sections 08.02 and 09.01.
03083-76(1980). "Specification for Flexible Poly(Vinyl Chloride)
Plastic Sheeting for Pond, Canal, and Reservoir Lining,"
Section 04.04.
D3421-75. "Recommended Practices for Extraction and Analysis of
Plasticizer Mixtures from Vinyl Chloride Plastics," Section
08.03.
D4491-85. "Test Methods for Water Permeability of Geotextiles by
Permittivity," Section 04.08
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Bass, J. 1986. Avoiding Failure of Leachate Collection and Cap Drainage
Systems. EPA 600/2-86/058 (NTIS PB 86-208 733/AS). U. S. Environmental
Protection Agency, Cincinnati, OH. 129 pp.
Bass, J. M., W. 0. Lyman, and J. P. Tratnyek. 1985. Assessment of Synthetic
Membrane Successes and Failures at Waste Storage and Disposal Sites.
EPA/600/2-85-100. U.S. Environmental Protection Agency, Cincinnati,
OH. 106 pp.
Christopher, B. R. 1982. Evaluations of Two Geotextile Installations in
Excess of a Decade Old. Paper presented at 1983 Annual Meeting of the
Transportation Research Board.
EPA. 1983. KES Dagoon Decommissioning Justification Document. EPA Contract
CX 103301-01-1. U.S. Environmental Protection Agency.
EPA. 1986. EPA Method 9090. Compatibility Test for Wastes and Membrane
Liners. In: Test Methods for Evaluating Solid Waste. Vol. 1A: Labora-
tory Manual, Physical/Chemical Methods. 3rd ed. SW-846. U.S. En-
vironmental Protection Agency, Washington, D.C. September 30, 1986.
Emcon Associates. 1983. Field Assessment of Site Closure, Boone County,
Kentucky. EPA 600/9-83-058. U.S. Environmental Protection Agency,
Cincinnati, OH.
Ghassemi, M., M. Haro, and L. Fargo. 1984. Assessment of Hazardous Waste
Surface Impoundment Technology: Case Studies and Perspectives of
Experts. EPA Contract No. 68-02-3174. U.S. Environmental Protection,
Agency, Cincinnati, OH. 300 pp.
Giroud, J. P. 1984a. Case Studies on Assessment of Synthetic Membrane
Performance at Waste Disposal Facilities. Draft. EPA Contract No.
68-03-1772. U.S. Environmental Protection Agency, Cincinnati, OH.
282 pp.
Giroud, J. P. 1984b. Aging of PVC Geomembranes in Uranium Mine Tailings
Ponds. In: Proceedings of the International Conference on Geomembranes,
Denver, CO, June 20-24, 1984. Vol. 2. Industrial Fabrics Association
International, St. Paul, MN. pp. 311-316.
Haxo, H. E. 1981. Testing of Materials for Use in Lining Waste Disposal
Facilities. In: Hazardous Solid Waste Testing, First Conference, eds.,
R. A. Conway and B. C. Malloy. ASTM Special Technical Publication 760.
ASTM, Philadelphia, PA. pp 269-292.
Haxo, H. E. 1982. Effect on Liner Materials of Long-Term Exposure in Waste
Environments. In: Proceedings of the Eighth Annual Research Symposium:
Land Disposal of Hazardous Wastes. EPA-600/9-82-002. U.S. Environ-
mental Protection Agency, Cincinnati, OH. pp 191-211.
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Haxo, H. E. 1983. Analysis and Fingerprinting of Unexposed and Exposed
Polymeric Membrane Liners. In: Proceedings of the Ninth Annual Research
Symposium: Land Disposal, Incineration, and Treatment of Hazardous
Waste. EPA-600/9-83-018. U.S. Environmental Protection Agency,
Cincinnati, OH. pp 157-171.
Haxo, H. E. 1987. Assessment of Techniques for In Situ Repair of Flexible
Membrane Liners: Final Report. EPA-600/S2-87-038. U.S. Environmental
Protection Agency, Cincinnati, OH. 61 pp. NTIS No. PB 87-191-813.
Haxo, H. E., R. S. Haxo, N. A. Nelson, P. D. Haxo, R. M. White, and S. Dakes-
sian. 1985a. Liner Materials Exposed to Hazardous and Toxic Wastes.
EPA-600/2-84-169. NTIS No. PB 85-121-333. U.S. Environmental Protection
Agency, Cincinnati, OH. 256 pp.
Haxo, H. E., R. M. White, P. D. Haxo, and M. A. Fong. 1982. Final Report:
Evaluation of Liner Materials Exposed to Municipal Solid Waste Leachate.
NTIS No. PB 83-147-801. U.S. Environmental Protection Agency,
Cincinnati, OH.
Haxo, H. E., R. S. Haxo, and G. L. Walvatne. 1987. Field Verification
of FMLs—Assessment of an Uncovered Unreinforced 60-Mil EPDM Liner After
18 Years of Exposure. In: Proceedings of the Thirteenth Annual Research
Symposium: Land Disposal of Hazardous Waste, May 6-8, 1987. EPA/600/
9-87/015. U.S. Environmental Protection Agency, Cincinnati, OH.
pp 38-50.
Morrison, W. R. 1984. Performance of Plastic Canal Linings. In: Pro-
ceedings of the International Conference on Geomembranes, June 20-24,
1984. Denver, Co. Vol 2. Industrial Fabrics Association Interna-
tional, St. Paul, MN. pp 321-325.
Morrison, W. R., and Starbuck, J. G. 1984. Performance of Plastic Canal
Linings. REC-ERC-84-1. Bureau of Reclamation, Denver, CO.
Nelson, N. A., H. E. Haxo, and Peter McGlew. 1985. Recovery and Testing
of a Synthetic Liner from a Waste Lagoon After Long-Term Exposure. In:
Proceedings of the Eleventh Annual Research Symposium: Land Disposal of
Hazardous Waste. EPA/600/9-85/013. U.S. Environmental Protection
Agency, Cincinnati, OH. pp. 296-306.
Pohland, F. G., D. E. Shank, R. E. Benson, and H. H. Timmerman. 1979. Pilot
Scale Investigations of Accelerated Landfill Stablization with Leachate
Recycle. In: Municipal Solid Waste: Land Disposal. Proceedings of
Fifth Annual Research Symposium. EPA 600/9-79-023a. U.S. Environmental
Protection Agency, Cincinnati, OH. pp. 283-295.
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Ramke, H. G. 1986. Uberlegungen zur Gestaltung and Unterhaltung von
Entwasserungssystemen bei HausmulIdeponien (Considerations on the
Construction and Maintenance of Leachate Collection and Removal Systems
for MSW Landfills). In: Fortshritte der Deponietechnik. K. P. Fehlau
and K. Stief, eds. Verlag Erich Schmidt, Berlin, pp 251-291. [Trans-
lation available from U.S. Environmental Protection Agency, Cincinnati,
OH. (TR-87-0119). 55 pp].
Richardson, G. N., and R. M. Koerner. 1987. Geosynthetic Design Guidance
for Hazardous Waste Landfill Cells and Surface Impoundments. Geo-
synthetic Research Institute, Philadelphia, PA.
Roberts, S., N. A. Nelson, and H. E. Haxo. 1983. Evaluation of a Waste Im-
poundment Liner System After Long-term Exposure. In: Proceedings of the
Ninth Annual Research Symposium: Land Disposal, Incineration, and Treat-
ment of Hazardous Waste. EPA-600/9-83-018. U.S. EPA, Cincinnati, Ohio.
pp 172-187.
Strong, A. G. 1980. The Deterioration of Rubber and Plastics Linings on
Outdoor Exposure: Factors Influencing Their Longevity. In: The Role of
Rubber in Water Conservation and Pollution Control. Proceedings of the
Henry C. Remsberg Memorial Education Symposium, 117th Meeting, Rubber
Division, American Chemical Society, May 22, 1980, Las Vegas, NV. The
John H. Gifford Memorial Library a Information Center, The Univeristy of
Akron, Akron, OH. pp IV-1--IV-46.
U.S. General Services Adminstration. 1980. FTMS 101C, Method 2065: Puncture
Resistance and Elongation Test (1/8-Inch Probe Method). In: Federal Test
Method Standard 101C. U.S. Services Administration, Washington, D.C.
Wigh, R. 0., and D. R. Brunner. 1981. Summary of Landfill Research - Boone
County Field Site. In: Land Disposal - Municipal Solid Waste. Proceed-
ings of Seventh Annual Research Symposium. EPA 600/9-81-022a. U.S.
Environmental Protection Agency, Cincinnati, OH. pp 209-242.
6-91
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CHAPTER 7
DESIGN OF LINED WASTE STORAGE AND DISPOSAL UNITS
7.1 INTRODUCTION
Containment units are lined for two basic reasons:
- To control the escape of constituents of the impounded material
and thereby protect the groundwater environment.
- To store material, e.g. for resource recovery or recycling.
Types of lined containment units include surface impoundments, hazardous
waste landfills, MSW landfills, waste piles, and heap leach pads. Because
the range of variables involved in designing a containment unit and the high
level of confidence that is required to meet statutory requirements for
controlling the migration of constituents of materials contained in the unit
(e.g. hazardous wastes), the planning and design of a lined containment unit
can become highly complex.
Designing of waste containment units is guided by two separate, but
equally important, sets of requirements. The first is meeting statutory and
regulatory requirements; the second is the exercise of sound engineering
judgment. Regulations promulgated under the Resource Conservation and
Recovery Act (RCRA) state minimum performance requirements for the design
and operation of storage and disposal units for the containment of solid
wastes (40 CFR 257). The Hazardous and Solid Waste Amendments (HSWA) of 1984
to RCRA stated minimum technological requirements for hazardous waste land-
fills and surface impoundments. Regulations based on these requirements have
been published in 40 CFR 264. Draft guidance documents for meeting RCRA and
HSWA requirements for the containment of hazardous wastes have been released
by the EPA for public comment and use (EPA, 1985; EPA, 1987a). These docu-
ments detail minimum technological guidance for the critical components of
both lining and cover systems. This guidance is based on engineering judg-
ment and is subject to change as changes in the relevant technologies change
and improvements occur. Further proposed rules detailing minimum tech-
nological requirements for meeting RCRA and HSWA requirements have also been
published (EPA, 1986a; EPA, 1987b). At the present time (May 1988), the EPA
is in the process of developing a final rule on the minimum technological
requirements for hazardous waste treatment, storage, or disposal facilities
7-1
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(TSDFs) for publication in the near future. At present, the EPA has not
developed minimum technology requirements for nonhazardous waste TSDFs. It
should be noted that, in addition to the statutory requirements for waste
TSDFs promulgated by the EPA, individual state and local authorities may have
codified various requirements.
In addition to meeting regulatory requirements, the designer of a waste
containment unit must also exercise sound engineering judgment. In designing
a containment unit, meeting minimum technological requirements as set forth
by RCRA regulations may appear to be relatively straightforward. However,
due to the evolving nature of waste containment technology, the number and
complexity of the operational variables encountered in the field environment,
and the interactive nature of many of these variables, exercise of sound
engineering judgment is complex. For example, insofar as all design de-
cisions should be made through the exercise of engineering judgment, certain
site-specific factors may require that regulatory minimums be exceeded.
This chapter discusses the minimum performance and technological re-
quirements for the design of lined waste containment units and reviews
engineering options available to the designer, with particular emphasis on
the design of hazardous waste TSDFs. This information can be used by site
owners and operators, permit writers, and those responsible for preparing
permit applications to aid them in gaining a comprehensive understanding of
the numerous elements involved in the design and construction of waste
containment units. This chapter can also be used by researchers and mate-
rials and component suppliers as a source of information on the design of
various types of waste containment units.
7.2 TYPES OF CONSTRUCTED CONTAINMENT UNITS
From a construction point of view, the three major types of containment
units are as follows:
- Totally excavated.
- Diked (i.e. totally aboveground).
- Combination.
Figures 7-1 through 7-3 schematically illustrate excavated, diked, and com-
bination surface impoundments. Excavated units are dug from a surface such
that the major portion of the capacity is below the grade of the surrounding
land surface (Figure 7-1). Diked units are built up above grade such that
the major portion of the capacity is elevated higher than the immediate sur-
roundings (Figure 7-2). Combination units result when material is both
excavated and filled (Figure 7-3). The construction of a particular type of
unit at a specific site depends on economic, hydrogeologic, regulatory, and
other site-specific factors.
7-2
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Figure 7-1.
An excavated
1980, p 8-6).
surface impoundment (Source: EPRI
Excavated units are generally found in relatively flat areas where
excavatable soil of a suitable nature exists (e.g. alluvium). As soil is
excavated, some may be left at the perimeter of the excavation to be used for
berm construction and levelling. The remainder of the material may be used
for daily cover (if the unit is a landfill), for general grading, or for fill
in other construction activities.
Diked, or aboveground, units are generally constructed at sites with
bedrock near or at the surface because the cost of blasting and excavating
precludes excavated units. This type of unit is becoming more common
waste disposal becomes more expensive.
construction of
preclude the economical
materials (sand, silt,
hauled in from off-site
with a high water table
is becoming more common as
Where local geologic considerations
excavated units, the desirable earth
or clay) for berm and bottom construction are often
locations. Diked units are also constructed at sites
and capillary zones.
A special type of diked unit can be built in an existing valley. An
earthen dike is constructed between the valley walls and across the valley
floor (Figure 7-4). Earth materials are used to prepare the sides and
bottoms of the unit prior to liner installation. In designing valley span
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Figure 7-2. Diked surface impoundment constructed above-grade (Source: EPRI, 1980, p 8-5)
-------
Figure 7-3. Diked surface impoundment partially excavated below grade
(Source: EPRI, 1980, p 8-4).
Downgradient Barm
Figure 7-4. A cross-valley surface impoundment configuration (Source:
EPRI, 1980).
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units, special consideration is given to managing the waste placement along
with the flow of surface and subsurface runoff. The downgradient berm should
be in place at the time waste is placed in the unit in order to provide
passive restraint against gravitational and/or dynamic forces of the mass.
Most storage and disposal units can be classified as combination ex-
cavation-fill impoundments because a balanced cut-fill project generally
results in the best economics.
7.3 FACTORS IN DESIGNING A LINED CONTAINMENT UNIT
This section discusses some key factors that must be considered in
designing a waste containment unit, including:
- Site-specific factors.
- Regulatory requirements and minimum guidance developed by the EPA.
7.3.1 Site-Specific Factors in Designing a Waste Containment Unit
The design of a waste containment unit can be greatly influenced
by various site-specific factors. These factors can be separated into
operational factors, hydrogeological factors, climatic factors, locational
factors, and biological factors. Table 7-1 lists factors that need to be
considered in designing various types of waste containment units. Many of
these factors and their effect on unit design are discussed in the following
subsections.
7.3.1.1 Operational Factors —
7.3.1.1.1 Purpose of the unit—The purpose of the unit significantly
affects the design and the type of operational factors that need to be con-
sidered in the design. For example, settling ponds can require significantly
different designs from hazardous waste landfills. Important differences can
include the necessity of collecting leachate in a landfill, the probable
necessity of conveying supernatant liquid out of a settling pond, different
regulatory requirements, etc.
7.3.1.1.2 Characteristics of the waste to be contained—In designing
a waste containment unit it is important to consider the possible inter-
action between constituents of the waste to be contained and components of
the lining system. For example, the organic constituents that may be present
in a hazardous waste landfill or surface impoundment may have a significant
effect on the polymeric components of the lining system. Some of the or-
ganics may be volatile and be able to migrate throughout the landfill. These
organics may permeate the FML and be absorbed by the other components of
the lining system, such as geotextiles and geonets, which are not in direct
contact with the leachate. Depending on the organic, this absorption can
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TABLE 7-1. SITE-SPECIFIC FACTORS TO BE CONSIDERED
IN DESIGNING A WASTE CONTAINMENT UNIT
Operational Factors:
- Purpose of the unit, i.e. whether the unit is for temporary storage or
permanent disposal and whether the waste to be contained is hazardous.
- Characteristics of the waste to be contained, including unusual
variations, e.g. composition, concentration, temperature.
- Desired service life of the unit.
- Pre-existing operational systems for conveyance of wastes into and/or
out of a unit, e.g. from mining operations.
- Acceptable seepage rate out of unit.
- Projected use of closed facility.
- Desired dimensions and capacity of unit.
- Estimated leachate volume during the active life of a landfill
(dependent on climatological factors).
- Harvesting or reycling/recovery programs, e.g. in settling ponds.
- Waste flow variation and discharge velocity, e.g. for a settling pond.
- Groundwater monitoring requirements.
- Berm width requirements.
- Requirements for monitoring conditions of lining system, e.g. coupon
testing.
Hydrogeological Factors:
- Characteristics of in-place soils at facility site.
- Subgrade characteristics as determined by soil borings.
- Location and type of bedrock.
- Competency of bedrock.
- Location of uppermost aquifer and other hydraulically interconnected
aquifers beneath facility property.
- Groundwater flow direction and rate.
continued . . .
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TABLE 7-1 (CONTINUED)
- Location of capillary zones.
- Seismic history of area.
- Proximity to faults.
- Floodplain level.
- Presence of surface waters including intermittent streams.
- Site topography.
Climatological Factors:
- Ambient temperature, including average and range.
- Prevailing wind speed and direction.
- Precipitation.
- Solar radiation.
- Evapotranspiration.
- Underground temperature (i.e. predicted service temperature of buried
lining system).
Locational Factors:
- Public relations.
- Adequacy of buffer zones.
- Surrounding land uses (commerical, residential, agricultural).
- Proximity to major waste generators.
- Regulations regarding locations of containment facilities.
- Regulations regarding design and operation at specific location.
Biological Factors:
- Local vegetation.
- Presence of indigenous burrowing animals.
- Presence of microorganisms.
- Potential for gas production underneath lined unit.
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soften polymeric drainage materials (e.g. geonets and geocomposites) and
thus, in conjunction with the overburden placed on a drainage system, can
reduce the drainage capacity of a system that depends on a polymeric drainage
medium. In addition, dissolved organics may interact with an FML to alter
its initially low permeability and change its mechanical properties. Know-
ledge about the composition of a waste liquid or leachate is important in
making an initial judgment about the compatibility of the waste liquid and
different components of the lining system.
The types of wastes that may be placed in a lined containment unit are
discussed in Chapter 2. Chapter 5 presents data from studies investigating
the interaction between actual waste liquids, leachates, or test liquids and
various types of lining materials, particularly FMLs. Goldman et al (1985)
summarize the results of selected studies investigating the effect of inter-
actions between chemicals and clays on soil liner hydraulic conductivity.
7.3.1.1.3 Configuration and dimensions of the unit—The most economical
shape for a containment unit is a rectangle with straight sides. Curved
sides and irregular shapes usually add to the grading and installation costs
and increase the number of structural failure points that can occur. The
construction of circular containment units result in significantly higher
grading costs, installation costs for liner materials, and overall construc-
tion costs.
7.3.1.1.4 Recycling/recovery operations—Some surface impoundments
functioning as settling ponds for the recovery of water can require sludge
removal or other dredging operations. Because of the potential for damage to
a liner during these operations, the design should include measures to
protect the liner. Where mechanical equipment is used, the EPA presently
recommends a minimum of 18 in. of protective soil, or the equivalent, cover-
ing the top liner except in cases in which it is known that the FML will not
be damaged by the sludge removal practices (EPA, 1985).
7.3.1.1.5 Berm width requirements—The width of the top of the contain-
ment embankments will be determined by their height and the design side
slope. Thus, the berm must be sufficiently wide to provide adequate strength
to the embankments. From an operational point of view, the minimum suggested
top width is 10 ft in order to allow sufficient room for equipment and per-
sonnel to operate during liner installation, to provide enough room so that
anchor trenches can be efficiently installed, and to facilitate maintenance
and repairs throughout the unit's active life, particularly in the case of
surface impoundments.
7.3.1.1.6 Inflow/outflow/overflow conveyances—The fewer penetrations
in a lined containment unit, the lower the potential for breaches in the
liner system; thus, in the case of the surface impoundments, inflow/outflow
piping designed to go "over the top" is generally preferred. If inflow/
outflow penetrations through a liner are required, pipes made of materials
that are compatible with the liner type and the waste liquid need to be used.
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During construction of the unit, soil around the pipes should be well com-
pacted to ensure that voids and loosening of the structures (e.g. an inflow
pipe) due to variable subsidence of the soil base are eliminated to prevent
breakage. In some cases, it may be desirable to construct a concrete base
below the penetration. If an "over the top" inflow pipe is used, a splash
pad may be needed to prevent damage to the liner. In the case of landfills,
construction of the sump system outside the unit may be desirable under some
circumstances.
7.3.1.1.7 Estimated leachate volume in a 1 andfi 11--The volume of
leachate produced in a landfillunitis primarily a function of the amount
of water that flows through the solid waste. Precipitation is a key factor
affecting the volume of leachate produced; thus, in regions of moderate-to-
heavy rainfall, leachate generation can be significant. The estimated amount
of leachate produced by a unit is important for designing the leachate
collection and removal systems which need to be designed to handle a maximum
expected volume, e.g. the leachate volume predicted from a 24-hour, 25-year
storm, while ensuring that the leachate depth over the liner does not exceed
30 cm (1 ft).
A tool for predicting with a reasonable degree of accuracy the quantity
of leachate that a given landfill can be expected to produce under a number
of different scenarios has been developed, based on the water balance method
of Thornthwaite and Mather (1955) in the soil and water conservation field.
Computer models has been developed to simulate hydrologic characteristics of
landfill operations (Perrier and Gibson, 1982; Schroeder et al, 1984a and
1984b).
The water balance method is a mathematical accounting process which
considers precipitation, evapotranspiration, surface run-off, and soil
moisture storage, all of which have a bearing on the extent to which in-
filtration can be expected to occur after a rain. Since infiltration is the
major contributor to leachate generation, knowing how much can be expected
under a given set of site conditions will provide the designer with valuable
information on which to base the design, particularly for the leachate col-
lection and removal system (LCRS) above a top liner. Figure 7-5 schematical-
ly illustrates, for an unlined MSW landfill, some of the factors that can
affect the volume of leachate produced.
The Hydrologic Evaluation of Landfill Performance (HELP) model is the
most recent computer simulation tool that has been developed to assist
landfill designers and regulators (Schroeder et al, 1984a and 1984b). This
program simulates the performance of alternative designs using climatologi-
cal, soil, and design data to produce estimates of water movement across,
into, through, and out of a landfill.
In designing a trial landfill configuration, four types of layers can be
arranged into a profile with up to nine layers. These four types of layers
include:
- Vertical percolation layers (e.g. the daily cover or the vegetative
cover on a closed landfill).
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- Lateral drainage layers (e.g. a leachate collection and removal
system).
- Waste layers.
- Barrier layers (i.e. a soil liner with or without an FML).
Figure 7-5. Percolation through a closed MSW landfill and movement of the
leachate into the soil environment.
Variables for each layer need to be defined, including:
- Thickness.
- Porosity (i.e. the ratio of the volume of voids to the total volume
occupied by a soil).
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- Field capacity (i.e. the ratio of the volume of water that a soil
retains after gravity drainage stops to the total volume occupied
by a soil).
- Wilting point (i.e. the ratio of the volume of water that a soil
retains after plants can no longer extract water (thus, the plants
remain wilted) to the total volume occupied by a soil.
- Saturated hydraulic conductivity.
- Evaporation coefficient (i.e. a value that indicates the relative ease
by which water is transmitted through soil in response to capillary
suction).
- Whether or not the layer was compacted.
In addition, the total surface area of the landfill and the drainage slope
and the maximum drainage distance in the drainage layers need to be defined.
Default data for various types of soils are available in the program.
In simulating the performance of the trial landfill design, various
climatological factors are taken into consideration, including:
- Daily precipitation.
- Mean monthly temperatures.
- Mean monthly insolation (i.e. solar radiation).
- Leaf area indexes (i.e. a dimensionless ratio of leaf area of active-
ly-transpiring vegetation to the nominal surface area of land).
- Winter cover factors, which account for the insulating effect of
dormant vegetation on the rate of evaporation from the soil.
- The evaporative zone depth (i.e. the maximum depth from which water
may be removed from the landfill by evapotranspiration).
Default climatological data for 102 cities are available in the program.
Simulations representing between 2 and 5 years of landfill performance
can be performed, generating values for precipitation, surface runoff, evapo-
transpiration, percolation through the base of each subprofile, and lateral
drainage from each subprofile. These values can be reported on a daily,
monthly, or yearly basis. Thus, the program can be used to estimate the
magnitudes of various components of the water budget, including the volume of
leachate produced by the fill and the thickness of the water-saturated layer
(i.e. the hydraulic head) above the barrier layers (i.e. the liner or the
cover system). These results can be used to compare the leachate production
potential of alternative designs, select and size appropriate leachate col-
lection and removal systems, and size leachate treatment facilities. Two
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verification studies of the HELP model have been performed (Schroeder and
Peyton, 1987a and 1987b). Version 2 of the model is now available in a draft
form for public comment.
7.3.1.2 Hydrogeological Factors--
7.3.1.2.1 Characteristics of in situ soils—The characteristics of the
JH sif-u soil materials are important because of their use in the foundation
and their potential use in soil liner and embankment construction. If the
native soils are found to be unsuitable for use in constructing the liner or
the embankments, borrow sources need to be identified and investigated. Soil
characteristics are also a necessary element in analyzing slope stability and
determining whether special design measures are necessary for controlling
settlement. The classification, relative homogeneity, and relevant physical,
mechanical, and chemical characteristics of the j_n situ soils need to be
determined. During the site investigation, the soils need to be tested for
Atterberg limits and grain size relative to "shrink/swell" moisture, den-
sity, strength, consolidation, permeability, organic material content, clay
mineralogy, cation-exchange capacity, and solubility in accordance with
appropriate soils engineering test methods. These tests are described by
Spigolon and Kelley (1984) and Goldman et al (1985). Chapman (1965) presents
a method for measuring cation-exchange capacity. Other methods include those
developed by the EPA [Methods 9080 and 9081 (EPA, 1986c)]. Elements of a
site investigation are discussed in Section 7.4.
Soil materials used in the construction of waste containment units
should have stable characteristics under different loading and climatic/
meteorological conditions and over a range of moisture contents. Soils which
have high "shrink/swell" characteristics are generally avoided. The changes
that occur in soils that experience excessive expansion when wet and contrac-
tion when allowed to dry may act to weaken an earthen structure, both at the
bottom and on the sidewalls/berm structures, if the structure is allowed to
be alternately wet and dry. Unwanted voids may be generated by repeated
"shrink/swell" cycles and may compromise the integrity of the liner system.
The presence of decomposing organic material in a soil below a lining
system can result in gas generation and subsidence problems. These problems
and their effects on the design of a containment unit are discussed in
Section 7.3.1.4.2. The presence of soluble material in the soil beneath an
FML can also result in similar problems. Any acid leakage, however minimal,
which could reach a carbonate rich soil, might produce quantities of gas
resulting in a catastrophic liner failure. The dissolution of the carbonate
in the soil by the acid might also cause cavities below the liner and loss
of liner support. Giroud (1984) reports how leakage of an acidic liquid
through small holes in a liner dissolved the underlying acid-sensitive soil,
eventually resulting in the rupture of the FML (see Section 6.4.2.1).
7.3.1.2.2 Subgrade characteristics—The subgrade serves as the foun-
dation by providing a relatively firm and unyielding support for the entire
lining system. In this sense, the subgrade includes all soil below what is
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excavated, all engineered fill, and all trench backfill. The performance of
the subgrade is dependent on:
- The loading it is subjected to by the combined weight of the lining
system and the waste.
- The characteristics of the subgrade soils.
- The uniformity of compaction during construction of the foundation.
- Slope stability.
- Changes in the groundwater.
- The performance of the liner.
- Seismic activity.
The main characteristics of relevance for subgrade materials are im-
mediate settlement (stress-strain relationship), long-term settlement or
consolidation (stress-strain-time relationship), strength, and acid solu-
bility. These parameters are readily determinable by field and laboratory
tests. Simpler, less expensive tests which have been previously correlated
with these tests can be performed during construction as part of the con-
struction QC/QA programs. These simpler tests include Atterberg limits,
grain size, and compaction tests. Strength, permeability, and consolidation
tests may also be performed on the subgrade earthwork, if deemed necessary.
7.3.1.2.3 Presence of hydro!ogic pathways—The presence of hydrologic
pathways such as fractures and sand seams can contribute to rapid migration
of wastes from a containment unit if liner failure occurs. In addition, if a
liner system intersects these pathways, pressures can build against the
outside of the system, possibly resulting in heaving, slope failure, and
liner rupture. Provisions for sealing these pathways need to be incorporated
into the unit design.
7.3.1.2.4 Location and type of bedrock—The location of bedrock under-
neat hHTTTIfeHrna^TeliirrrlFTc^^(through blasting and other procedures)
and rock shaping in order to construct an excavated unit. However, the cost
of working in intact rock is many times greater than construction activity
in weathered rock or soils. In addition, the potential for large angular
particles and irregular surfaces is much greater. It may be more economical
under such circumstances to construct a diked unit.
The in situ rock quality is also important for assessing the presence of
hydrologic pathways and the potential for leakage from a site. The higher
the rock quality (i.e. the larger the percentage of intact rock), the greater
the ability of the site to contain whatever leakage occurs through the lining
system. In situ rock quality can be estimated by a modified core recovery
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ratio known as the rock quality designation (RQD) (Deere, 1963). RQD is
determined by measuring the total length of the pieces recovered in the
core that measure 10 cm (4 in.) in length or longer and dividing this length
by the total length of the core. The resulting value is reported as a
percentage.
7.3.1.2.5 Seismic history of area and proximity to faults—Current (as
of 1986) EPA regulations require new hazardous waste TSDF units to be con-
structed at least 61 meters (200 ft) from a fault which has had displacement
in Holocene time (40 CFR 264.18). Proximity to faults can affect decisions
regarding penetrating the lining (if penetrations are being considered) and
embankment design.
7.3.1.2.6 Location of uppermost aquifer--In designing a facility
it isimportant to know the location of the uppermost aquifer, including
seasonal groundwater level variations, from both a design standpoint and a
regulatory standpoint. Depending on the type of waste being contained and
the geographical location of the facility, a specific distance between the
unit base and the water table may be required. For sites with high water
tables, this may necessitate aboveground unit design. Present EPA guidance
for the design and construction of hazardous waste TSDFs require the lining
system to be constructed completely above the seasonal high water table (EPA,
1985). If the base of the unit is allowed to extend below the water table,
special intragradient (below water table) design provisions will be required.
7.3.1.2.7 Surface and groundwater drainage considerations—If the
containment unit isin the naturalpathway of either surface or subsurface
drainage (including intermittent streams), diversion drainage systems,
overflow structures, and subterranean diversion systems must be designed as
required to handle the water excesses in order to minimize potential damage
to the unit structure and prevent washout of the waste. Outside grades or
drainage ditches may be required to prevent run-off from entering the unit,
or an underdrain system may be required to remove groundwater which may ac-
cumulate beneath the installed liner with time. In addition, the directions
of groundwater flow will determine the placement of the monitoring wells.
Infiltrating water beneath units is particularly common in areas with high
subsurface flow, or high groundwater table; the problem needs to be recog-
nized in advance so that design accommodations can be made if the integrity
of both the containment unit and the liner is to be maintained throughout
its projected life. Areas subject to flooding and areas with high water
tables must receive special design, construction, operations, and maintenance
concern.
7.3.1.2.8 Floodplain level—Except for those cases that qualify for
statutory exemption, current (as of 1986) EPA regulations require hazardous
waste TSDF units located in a 100-year floodplain to be designed, construct-
ed, and maintained to prevent washout of any waste by a 100-year flood (40
CFR 264.18).
7.3.1.2.9 Site topography—The site's topography can influence unit
configuration and the run-on/run-off control drainage system design. For
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example, special cut-off trenches may be necessary in mountainous regions to
prevent large quantities of surface run-off from entering the unit and to
protect the integrity of the unit's structure.
7.3.1.3 Climatological Factors —
7.3.1.3.1 Prevailing wind speed and direction—The design of a surface
impoundmentneedstoconsider theprevailing winds. Winds can adversely
affect an FML in two ways: first, in the form of wave action as the wind
impinges on the liner or cover, and secondly, in the form of lifting action
on the slopes. Proper venting of an FML at the top of the slope can mitigate
or negate the airfoil effect created by the slope. The placement of weighted
tubes (e.g. sand bags) on the slopes also helps to break up the flow of air
across the unit in addition to providing ballast to hold an FML on the slope.
Dedrick (1974 and 1975) has developed models for analyzing air pressure over
surfaces exposed to wind for water harvesting catchments and reservoirs.
Wayne and Koerner (1988) apply the information developed by Dedrick (1974 and
1975) to solid waste land disposal units and surface impoundments during
construction and prior to filling and develop a design methodology which can
be used in determining the magnitude and distribution of tractive (uplift)
forces on FML systems.
7.3.1.3.2 Ambient temperature—The temperature characteristics of the
environment can be a factor in the liner selection process. Of particular
significance are temperature extremes and the duration of those extremes.
Materials that exhibit superior low temperature resistance to cracking may
not be able to withstand the effects of high temperatures. Low temperatures
along with strong winds can result in a flex fatigue type failure of an FML.
Freeze-thaw cycling can affect the integrity of the subgrade. Materials
that creep at high temperatures may elongate to failure during cycles of high
temperature (Small, 1980). Workmanship for installing a liner may suffer if
performed during a period of extreme temperatures.
7.3.1.4 Biological Factors—
7.3.1.4.1 Local vegetation—Vegetation can jeopardize liner integrity
as a result of growth. Although there is no evidence of roots penetrating
FMLs, certain grasses have been known to penetrate FMLs from underneath,
particularly on the slopes and berms of surface impoundments where no soil
cover has been placed on the liner. Use of thicker sheeting or sheeting with
a high puncture resistance may prevent such damage. Where certain woody
vegetation or grasses are evident, soil sterilization with an appropriate
nonpolluting herbicide may be required to prevent damage to the liner. Salt
grass, nut grass, and quackgrass are examples of vegetation that require
soil sterilization before installation of the liner. The top-soil layer
containing this vegetation should be removed as a part of subgrade prepa-
ration. If these grasses are present, soil sterilization should also be
automatically included in the construction process. If a soil sterilant is
used, FMLs should not be placed immediately after application. Time should
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be allowed for the sterilant to be absorbed by the soil or to lose its
volatile components so that it will not react with the liner.
7.3.1.4.2 Presence of indigenous burrowing animals—The presence of
burrowing animals at a site demands special design considerations, parti-
cularly for embankments or the final cover of a closed landfill (Johnson and
Dudderar, 1988). Animals of concern can include woodchucks, muskrats, ground
squirrels, moles, chipmunks, termites, etc. Compacted clay liners (e.g. the
cover for an
ing animals.
including:
MSW landfill) appear to be effective protection against burrow-
However, FMLs used in covers may require extra protection,
- Rip-rapping above the FML. Johnson and Dudderar (1988) recommend
the use of rock of about 6 in. in diameter to minimize the size of the
gaps between rocks and also to be large enough to resist excavation.
- Matting (e.g. Kevlar or Mylar), provided the matting is of sufficient
strength and durability.
- An anti-animal layer such as a biocide, irritant (e.g. cinders), or
repellant.
- The use of vegetation that is not attractive to burrowing animals.
In the case of embankments, a special vertical rock zone may be constructed
to prevent animals from burrowing into the unit.
7.3.1.4.3 Presence of microorganisms—The presence of microorganisms
such as bacteria and fungi in an LCRS can eventually result in clogging of
the drainage media either because of sedimentation of the system with bio-
logical by-products or because of growths which attach themselves to the
media and close off the drainage voids. Ramke (1986) describes mechanisms
related to biological activity which could result in clogging. Further
information is also presented by Bass (1986). Clogging of an LCRS above a
top liner in a landfill or a waste pile would allow the hydraulic head to
increase and could contribute to rupture of the FML; clogging of an LCRS
between the two liners of a double-liner system would prevent detection of a
leak in the top liner and prevent removal of the liquids entering the system.
An engineer needs to consider the potential for biological clogging in
designing an LCRS for a containment unit. The design should include features
that allow inspection of the drainage system. In addition, in case clogging
does eventually develop, procedures for remedial action should be explored,
and procedures compatible with the design need to be described. Flushing the
system periodically with biocides is one method that may prevent biological
clogging; however, the biocide needs to be environmentally safe, and it
should be demonstrated that the biocide does not adversely affect the FML and
the other polymeric components of the lining system, including synthetic
drainage materials if they have been included in the design. Design con-
sidererations for avoiding clogging are discussed by Ramke (1986) and Bass
(1986).
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7.3.1.4.4 Presence of organic material in the subgrade soi1--The
presence of decomposing organic material in a soil below a lining system
can cause a variety of problems. Organic material, unless it has already
degraded to terminal products, can generate gases (prnicipally methane and
carbon dioxide) through natural decay processes. In addition, tree trunks
and extensive root systems can create voids beneath the liner. If gases are
generated beneath a liner, they may collect to the extent that the liner is
pushed upward from the subgrade. In the case of a surface impoundment, FML
displacement by gases can result in the "whale back" effect where large
portions of liner rise up and out of the liquid being impounded (like a
ballon), eventually rupturing or requiring puncturing to release the trapped
gases. In addition, the development of "whale backs" can substantially
reduce the capacity of the impoundment. The decay of organic material can
also create voids which lead to slumping of the foundation, subsequent liner
shifting, and potential liner failure.
The installation of a gas venting system in conjunction with the removal
of organic material may be necessary if the soil contains organic material,
or if other gas problems are known for the particular site. In order to
encourage gas movement out from underneath a containment unit, the underside
of the unit needs to slope upwards with a minumum grade of 2% from a low
point. Since the venting system must contain porous materials with suf-
ficient transmissivity to allow gases to move underneath the entire unit and
provide a way of conveying collected gases to the atmosphere, it may also
serve as an underdrain. The designer may decide to provide for the collec-
tion and removal of liquids (e.g. perched groundwater) as well as the safe
discharge of the vented gases.
7.3.2 Statutory and Regulatory Requirements and EPA Guidance
for Waste Containment Units
The designer of a waste containment unit must be aware of the current
statutory and regulatory minimum design and operating requirements for waste
containment units. RCRA, which was passed in 1976, mandated that the EPA
promulgate regulations establishing performance standards and requirements
for the location, design, construction, and operation of solid waste TSDFs.
In response to this requirement, the EPA has codified performance standards
for solid waste TSDFs, set minimum technological requirements for hazardous
waste TSDFs, and developed draft minimum technology guidance documents on the
design, construction, and operation of hazardous waste TSDFs for comment and
use. In 1984, passage of HSWA established the double-liner requirement for
new hazardous waste landfills and surface impoundments, except under those
conditions that meet criteria for statutory variance.
This section reviews present (as of May 1988) statutory requirements,
EPA regulations, and EPA guidance concerning the design of hazardous and
nonhazardous solid waste TSDFs. It should be noted that these regulations
are under continuous review; it should also be noted that, in addition to
EPA regulations, state and local regulations may apply to the design of
waste containment units at a particular site.
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7.3.2.1 Performance Criteria for Solid Waste TSDFs--
The EPA regulations describing performance criteria for the design and
operation of solid waste TSDFs are presented in 40 CFR 257. These criteria
state general performance standards for determining whether a solid waste
TSDF poses a reasonable probability of adverse effects on health or the
environment in relation to:
- Performance within a floodplain.
- The effect of the unit or practice on endangered species.
- The effect of the unit or practice on surface water.
- The effect of the unit or practice on groundwater.
- The application of wastes containing cadmium or polychlorinated
biphenyls (PCBs) to land used for the production of food-chain
crops.
- The potential for disease propagation resulting from the unit or
practice (e.g. by disease vectors such as rodents, flies, and mos-
quitoes capable of transmitting diseases to humans and by the handling
of sewage sludge and septic tank pumpings).
- The effect of the unit or practice on air quality (with particular
reference to the open burning of wastes).
- The safety of the unit or practice (with particular reference to the
concentration of explosive gases, potential for fire hazard, bird
hazards to aircraft, and uncontrolled public access so as to expose
the public to potential health and safety hazards at the disposal
site).
At present (May 1988), the criteria set forth by EPA in 40 CFR 257 are
the only Federal regulatory requirements for the design of containment units
for managing wastes subject to regulation under RCRA Subtitle D (i.e. non-
hazardous wastes). Further proposed rules relating to the design, construc-
tion, and operation of Subtitle D waste containment units are due to be
released by the EPA for public comment in the near future.
7.3.2.2 Statutory and Regulatory Requirements for the Design
of Hazardous Waste TSDFs--
As knowledge about the environmental effects of the land disposal of
hazardous wastes increased, Congress amended RCRA in 1984 with HSWA, which
established minimum technological requirements for the design and construc-
tion of new hazardous waste landfills or surface impoundments, except in
cases where the conditions for statutory variance are met. These minimum
requirements include [Sec. 3004(o)(l)(A)]:
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- The installation of two or more liners and a leachate collection
system above (in the case of a landfill) and between such liners.
- Groundwater monitoring around the landfill or surface impoundment.
HSWA also required the EPA to promulgate regulations or issue guidance
documents regarding the implementation of the minimum technology require-
ments. Since then, the EPA has promulgated regulations detailing operation
and design requirements for hazardous waste TDSFs (40 CFR 264). The EPA has
also issued a draft minimum technology guidance document on double liner
systems for landfills and surface impoundments (EPA, 1985) and a similar
document on final covers for landfills and surface impoundments (EPA, 1987a).
Both the minimum technology requirement regulations and the technology
guidance documents are presently under review. EPA eventually will formalize
technology guidelines by incorporating them into the Agency's regulations.
A proposed rule was issued in March 1986 (EPA, 1986a), and a second
notice presenting additional information on the performance of bottom liners
in double-lined landfills and surface impoundments was issued in October 1986
(EPA, 1986b). Further proposed minimum technology requirements, particularly
with reference to the leachate detection, collection, and removal systems,
were published in another proposed rule issued in May 1987 (EPA, 1987b).
The EPA is in the process of developing a final rule for double liner and
leachate detection, collection, and removal systems, which is scheduled for
May 1989 publication.
This section describes the present EPA regulations (as of May 1988)
concerning the lining system design requirements for new hazardous waste
piles, surface impoundments, and landfills. Section 7.3.2.3 discusses the
double liner and final cover systems described in the draft minimum guidance
technology documents.
7.3.2.2.1 Design Requirements for Hazardous Waste Piles—Except for
those units exempted by regulation, a regional administrator of the EPA, or
some other regulatory agency, EPA regulations state that a waste pile must
have [40 CFR 264.251 (1986 ed.)]:
(a)(l) A liner that is designed, constructed, and installed to
prevent any migration of wastes out of the pile into the
adjacent subsurface soil or groundwater or surface water
at any time during the active life (including the closure
period) of the waste pile. The liner may be constructed
of materials that may allow waste to migrate into the
liner itself (but not into the adjacent subsurface soil
or groundwater or surface water) during the active life
of the facility. The liner must be:
(i) Constructed of materials that have appropriate
chemical properties and sufficient strength and
thickness to prevent failure due to pressure
gradients (including static head and external
hydrogeologic forces), physical contact with
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the waste or leachate to which they are ex-
posed, climatic conditions, the stress of
installation, and the stress of daily opera-
tion;
(ii) Placed upon a foundation or base capable of
providing support to the liner and resistance
to pressure gradients above and below the liner
to prevent failure of the liner due to settle-
ment, compression, or uplift; and
(iii) Installed to cover all surrounding earth likely
to be in contact with the waste or leachate.
(2) A leachate collection and removal system immediately
above the liner that is designed, constructed, main-
tained, and operated to collect and remove leachate from
the pile....The leachate depth over the liner [must] not
exceed 30 cm (1 ft). The leachate collection and removal
system must be:
(i) Constructed of materials that are:
(A) Chemically resistant to the waste managed
in the pile and the leachate expected to
be generated; and
(B) Of sufficient strength and thickness to
prevent collapse under the pressures
exerted by overlaying wastes, waste cover
materials, and by any equipment used at
the pile; and
(ii) Designed and operated to function without
clogging through the scheduled closure of the
waste pile.
The regulations also require a waste pile to have a run-on control system
which prevents flow onto the active portion of the pile during peak discharge
from at least a 24-hour, 25-year storm and a run-off management system to
collect and control at least the water volume resulting from a 24-hour,
25-year storm. If the pile contains any particulate matter that may be
subject to wind dispersal, the pile must be covered or otherwise managed to
prevent dispersal.
In essence, these regulations were written so as to allow the use
of a single soil or FML liner. However, ultimate design specifications for
new facilities still need the approval of a regulatory agency, i.e. either
the EPA or a state agency. Regulations extending the double-liner require-
ments to new hazardous waste piles have been proposed (EPA, 1987b).
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7.3.2.2.2 Design Requirements for Hazardous Waste Surface Impound-
ments—Except for those unites exempted by regulation, a regional adminis-
trator of the EPA, or some other regulatory agency, EPA regulations state
that all new surface impoundments must have [40 CFR 264.221 (1986 ed.)]:
...Two or more liners and a leachate collection system between
such liners. The liners and leachate collection system must
protect human health and the environment....The requirement for
the installation of two or more liners...may be satisfied by the
installation of a top liner designed, operated and constructed of
materials to prevent the migration of any constituent into such
liner during the period such facility remains in operation
(including any post-closure monitoring period), and a lower liner
designed, operated, and constructed to prevent the migration of
any constituent through such liner during such period. For
the purpose of the preceding sentence, a lower liner shall be
deemed to satisfy such requirement if it is constructed of at
least a 3-ft thick layer of recompacted clay or other natural
material with a permeability of no more than 1 x 10"? centimeter
per second.
The regulation concerning the top liner of the double liner system was
written so as to require the use of an FML. The regulations also require
that a surface impoundment must function without overtopping and that the
embankments for an impoundment must maintain their structural integrity and
that their structural integrity must be ensured without assuming that the
liner system will not leak during the active life of the unit. Requirements
for the structural integrity in the service environment, placement, and
coverage of the liners and the requirements for the leachate collection
system parallel those for waste piles.
7.3.2.2.3 Design Requirements for Hazardous Waste Landfills—Except for
those landfills exempted by regulation, a regional administrator of the EPA,
or some other regulatory agency, the EPA requirements for lining a new
hazardous waste landfill parallel those for surface impoundments except that
a leachate collection system is required above as well as between the two
liners [40 CFR 264.301 (1986 ed.)]. The requirements for a run-on control
system, a run off management system, and control of particulate matter to
prevent wind dispersal are the same as those for waste piles.
7.3.2.3 Draft EPA Guidance on Hazardous Waste Containment Units—
The present regulations promulgated by the EPA often represent design
goals rather than actual technological requirements for the design of hazard-
ous waste containment units; one example is the clause that "the liners and
leachate collection system must protect human health and the environment,"
which applies to both new surface impoundments and landfills. In order to
clarify implementation of the regulations and to allow for public review of
this guidance, the EPA released draft Minimum Technology Guidance (MTG)
documents on double liner and final cover systems for landfills and surface
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impoundments, including guidance on design, construction, and operation (EPA,
1985; EPA, 1987a). These documents were prepared as part of the process of
writing minimum technology regulations for the design, construction, and
closure of hazardous waste containment units and facilities.
This section discusses the double liner and final cover systems des-
cribed in the draft MTG documents. The minimum requirements for each
component of these systems are discussed in more detail in Section 7.5.
7.3.2.3.1 Draft EPA Guidance on Double Liner Systems — In the draft
minimum technology guidance document on double liner systems for hazardous
waste landfills and surface impoundments, two double liner systems are
described: an FML/composite double liner system and an FML/compacted soil
double liner system (EPA, 1985). Insofar as concern has arisen with respect
to the latter system, only the FML/composite double liner is described in
this section.
The FML/composite double liner system for a hazardous waste landfill
consists, at a minimum, of a primary leachate collection and removal system
(LCRS), a top FML liner, a secondary LCRS, and a bottom composite FML/low-
permeability soil liner. The secondary LCRS is also referred to as the
leak detection, collection and removal system (LDCRS). The lining system for
a surface impoundment is the same except that there is no primary LCRS. A
schematic cross section showing the basic components of the FML/composite
double liner system for landfill and surface impoundment units is presented
in Figure 7-6, which also presents the basic requirements for each component.
The thickness requirements for the LCRSs only apply if granular media are
used. LCRSs based on synthetic polymeric materials (e.g. geonets, geo-
composites, synthetic filters) may also be used if it is demonstrated that
they are equivalent to "conventional" granular systems with pipes, i.e. if
they meet the design requirements for drainage, ability to withstand expected
overburden pressures while maintaining their drainage capabilities, chemical
resistance, etc.
Each component of the lining system is intended to fulfill a specific
function and should meet the stated design requirements. The function of the
primary LCRS at a landfill is to minimize the head (depth) of leachate on the
top liner during the active life of the landfill unit and to remove liquids
through the post-closure care period, which for design purposes is nominally
assumed to be 30 years. The primary LCRS must be capable of maintaining a
leachate head of less than 1 foot. The recommended thickness for a graded
granular filter medium is greater than or equal to 6 inches. A granular
drainage medium is recommended to have a thickness of 12 in. or greater and a
hydraulic conductivity greater than or equal to 1 x 10-2 cm s-1.
The top liner should be designed, constructed, operated, and maintained
to control the escape of waste constituents during operation of the unit
including the post-closure care period. At a minimum, this liner should
consist of an FML with a minimum actual (not nominal) thickness of 30 mils.
The draft guidance document also suggested a requirement that the FML should
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MATERIALS
RECOMMENDED
DIMENSIONS AND SPECIFICATIONS
NOMENCLATURE
Graded Granular Fitter Medium
Granular Drain Material
(bedding)
Flexible Membrane Liner (FML)
Granular Drain Material
(bedding)
Flexible Membrane Liner (FML)
Low Permeability Soil, Compacted in Lifts
(soil liner material)
T_
O-
Thickness ^ 6 in.
Maximum Head on Top of Liner = 12 in.
Thickness > 12 in.
Hydraulic Conductivity > 1 x 10 "2 cm/sec
• Drain Pipe •
O
Thickness of FML > 30 mils
(see note)
Thickness > 12 in.
Hydraulic Conductivity > 1 x 10-2cm'sec
—— Drain Rpe
.Thickness of FML>30 mils
(see note)
Thickness > 36 in.
Hydraulic Conductivity <1 x 10"' cm/sec
-7
Prepared in 6 in. Lifts
Surface Scarified Between Lifts
Native Soil Foundation/Subcase
Unsaturated Zone
NOTE:
_. „ . . , . _ Groundwater Level
Values for FML thickness represent —
actual values at all points across
roll width. FML thickness > 45 mils
recommended if liner is not covered
within 3 months.
Figure 7-6. Schematic profile of an FML/composite double-liner system for a
waste landfill presenting EPA draft guidance. Synthetic drainage
synthetic filter media can be used instead of granular media
performance is demonstrated. (Based on EPA, 1985).
Solid Waste
Fitter Medium
Primary Leachate Collection
and Removal System
Top Liner (FML)
Secondary Leachate Collection
and Removal System
Compression Connection (contact)
Between Soil and FML
Bottom Liner (composite FML and
compacted tow permeability soil)
hazardous
media and
if equivalency
-------
allow no more than cte mini mis leakage of all polluting species through the
liner itself. The concept of de minimi's comes from the legal principle," de
law does not concern itself with triflesJT
to be that amount which is of no threat to
minimis leakage was in
will allow
e.g. via vapor transmission or very
non curat lex" (i.e. the
minimis leakage is considered
health or the environment. The allowance for de_
recognition of the fact that FMLs, since they are not impermeable,
some transmission of waste constituents,
minitms
TTeT~__
human
small imperfections.
The EPA is presently (June, 1988) Devaluating the use of the term de_
minimis and the requirement that an installed FML allow no more than de_
minimis leakage. In recently proposed regulations, the EPA discusses leakage
through a top liner in terms of an action leakage rate (ALR) (EPA, 1987b).
The ALR constitutes a trigger for initiating interactions between the owner/
operator and the EPA and the implementation of a predetermined response
action plan (RAP). The EPA has proposed an ALR of 5 to 20 gpad, which the
EPA believes is representative of a high level of construction quality
assurance at surface impoundments, or alternatively a site-specific ALR. In
the proposed regulations, RAPs are required for at least two leakage rates:
- Rapid and extremely large leakage (RLL), which is defined as the
maximum design leakage rate that the secondary LCRS can remove under
gravity flow conditions.
- Leaks less than rapid and extremely large but greater than the ALR.
For leaks that exceed the ALR but are less than rapid and large, the EPA
considers acceptable responses to include:
- Terminating receipt of waste and closing the unit.
- Repairing any leaks expeditiously.
- Instituting operational changes to reduce leakage into the LCRS
between the liners.
- Collecting and removing
groundwater monitoring.
leachate, and, in addition, accelerating
- Maintaining current operating
and removal of leachate).
procedures (including the collection
The secondary LCRS between the two liners should be designed, con-
structed, operated, monitored, and maintained to rapidly detect, collect, and
remove liquids entering the the collection system for treatment through the
post-closure care period. The recommendations for thickness and hydraulic
conductivity are the same as those for the drain material component of the
primary LCRS.
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The bottom liner consists of two components, an FML and a low-perme-
ability soil liner, which are intended to function as one system; hence, the
term "composite" liner. Like the top liner, the upper (FML) component of
the bottom liner should be designed, operated, and constructed to prevent
migration of any constituent of the waste liquid into the liner during the
period of facility operation, including the post-closure care period. The
recommended minimum thickness is 30 mils. The lower (soil) component of
the bottom liner should be designed, operated, and constructed to minimize
migration of any constituent of the waste liquid or leachate through the
upper component if a breach in the upper component were to occur prior to
the end of facility operation, including the post-closure care period.
The recommended thickness and hydraulic conductivity of the soil component
reflect the regulatory requirements (Section 7.3.2.2). The EPA believes
that this design is effective in protecting human health and the environment
because the combination of the two components in the bottom liner system
provides for virtually complete removal of waste or leachate by the secondary
LCRS if a leak were to occur in the top liner.
The guidance on the minimum requirements is described in more detail
in Section 7.5, which describes design options for components of a complete
liner system. Also described in that section is the double composite liner
option in which the top liner consists of a composite liner such as has been
suggested by Buranek and Pacey (1987), Buranek (1987), and other designers.
7.3.2.3.2 Draft EPA Guidance on Final Cover Systems—The draft document
presenting the EPA's mini'mum technology guidance on final covers for hazard-
ous waste landfills (EPA, 1987a) recommends a multilayer design (Figure 7-7)
consisting of the following layers from top to bottom:
- A vegetative layer consisting of an erosion control component (vege-
tation, gravel, etc.) and a 24-in. (60-cm) minimum thickness top
soil component. The top of the layer should have a final slope, after
allowance for settling and subsidence, of between 3 and 5%, including
side slopes to prevent pooling due to irregularities of the surface
and or vegetation, and excessive erosion. Erosion for any part of the
cover should not exceed 2.0 ton/acre/year, using the U.S. Department
of Agriculture Universal Soil Loss Equation (USLE).
- A drainage layer. If composed of sand, it should have a 12-in.
(30-cm) minimum thickness to prevent ponding on the underlying low-
permeability layer and to remove water that infiltrates through the
top layer of the cover. This layer also serves as a protective bed-
ding for the FML. The drainage media should have a minimum hydraulic
conductivity of 1 x 10~2 cm s"1, and the final bottom slope after
allowance for settlement should be at least 2%. A drainage system
based on synthetic materials can also be used if it is demonstrated
that the synthetic system is equivalent to the recommended granular
system.
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- A low-permeability layer which includes an
ness of 20 mils, and a minimum of 24 in.
which should have an in-place saturated
FML with a minimum thick-
(60 cm) of compacted soil
hydraulic conductivity of
1 x 10"? cm s~l or less. This layer serves to increase liquid removal
efficiency in
mi zing liquid
the drainage
infiltration.
layer and provides added backup for mini-
LAYER
VEGETATIVE
LAYER
DRAINAGE
LAYER
LOW PERMEABILITY
LAYER
COMPACTED
SOIL LAYER
FUNCTIONS
VEGETATION OR OTHER
EROSION CONTROL MATERIAL
AT AND ABOVE SURFACE
TOP SOIL FOR ROOT
GROWTH
REMOVE INFILTRATING
WATER
INCREASES EFFICIENCY
OF DRAINAGE LAYER AND
MINIMIZES INFILTRATION
INTO UNIT
NOTE:
GRANULAR OR GEOTEXTILE FILTERS AS APPROPRIATE
ARE TO BE INSTALLED BETWEEN LAYERS.
Figure 7-7.
Cover system
EPA, 1987a).
design recommended by EPA guidance (Source:
The EPA recognizes that there may be specific cases where an alternative de-
sign (e.g. fewer layers or optional layers) may be applicable. For instance,
in extremely arid regions, a gravel mulch may be needed over the topsoil to
compensate for lower vegetative coverage or the drainage layer may not be
required. In areas where burrowing animals may damage the low-permeability
layer, it may be necessary to place a stone layer above the FML component.
At a unit that is expected to produce gases, a gas-venting layer between the
waste and the low-permeability layer would be needed.
7.4 SITE INVESTIGATION
As with any earthwork project, a waste containment unit must be designed
for the geological conditions at the specific site because of the subsurface
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heterogeneity and spatial variability that is the rule in most geologic
settings. In addition, because the particular site may have been selected
for reasons other than its technical suitability for a containment unit, a
thorough site investigation is necessary in order to reveal conditions that
may require special design considerations. It is assumed that a preliminary
site investigation was performed as part of the site selection process and
that this investigation showed the suitability of constructing a waste
containment unit at the particular site.
Site investigations are conducted to delineate a site's topography,
subsurface geology, and hydrogeology. Ways in which these factors can affect
a design are discussed in Section 7.3. Steps of a site investigation include
the following:
- Compilation and review of existing data and information.
- A site reconnaissance.
- Indirect subsurface investigation.
- Direct subsurface investigation.
- Field tests to determine soil characteristics.
- Groundwater studies.
- Laboratory tests to determine soil characteristics.
Site investigations usually begin with compilation and review of exist-
ing information that pertain to the site. Sources of information include
Soil Conservation Service County Soil Surveys, U.S. Geological Survey topo-
graphic and surficial geology maps, aerial photographs, published literature,
state geological survey information, and county records of geotechnical tests
associated with previous construction projects. This information can be very
useful for planning the scope and approach of further site investigation
activities. The compilation and review should include data on the geo-
hydrologic regime of the region surrounding the site.
The design team visits the site to confirm how existing recorded data
and information correspond to conditions at the site. The reconnaissance
involves a complete walk-through of the site and observation of vegetation,
soil cover, soil types, rock outcrops, and any other conditions that could
affect the facility design. Observation of soil properties is based largely
on visual classification.
Indirect subsurface investigations, which are also known as geophysical
or nondestructive test evaluations, study the materials below the ground
surface without actual penetration into the subsurface materials. Indirect
subsurface investigative techniques include electrical resistivity and
inductance methods, electro-magnetic survey methods, seismic refraction, and
ground-penetrating radar. The use of a particular investigative technique
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can depend to a large degree on the geologic setting (White and Brandwein,
1982). Electrical resistivity and/or inductance surveying can be used to
locate the water table as well as the presence of subsurface layers or lenses
of different permeability that have contrasting resistivities (EPA, 1978;
Freeze and Cherry, 1979). Seismic refraction surveys can provide information
on the depth to bedrock, topography of the bedrock, and some physical prop-
erties of the subsurface soil (Cichowicz et al, 1981; Dobrin, 1960). Ground-
penetrating radar can be used to locate buried structures and pipes, and for
indicating depth to shallow bedrock (White and Brandwein, 1982). Proton
precession magnetometry, metal detectors, and electrical inductance devices
have also been used with varying degrees of success (Lord and Koerner, 1987).
These indirect techniques can be used to reduce the cost of direct investi-
gative techniques, such as drilling and laboratory testing, by providing a
large amount of information at a relatively low cost. This information can
also be used in planning direct site investigations which can then be carried
out as economically and as efficiently as possible. Unfortunately, most of
these methods require a good deal of skill to interpret the test results.
Direct methods of investigating the subsurface include drilling bore-
holes and wells and excavating pits and trenches. The purpose of these
methods is to expose subsurface material so that the physical conditions can
be directly observed and measured (e.g. faults, slickensides, sand seams,
depth to bedrock and to the water table, penetration tests, and j_n_ situ
permeability) and to obtain samples of surface material for laboratory test-
ing of engineering properties. Exploratory methods are described by the
Bureau of Reclamation (1974). Methods of testing the soils are described by
the Bureau of Reclamation (1974) and in ASTM Part 4.08. Methods of testing
soils are also discussed by Goldman et al (1985) and by Spigolon and Kelley
(1984). Detailed discussions of techniques for general geotechnical site
investigations may also be found in Winterkorn and Fang (1975) and Hunt
(1984).
Geohydrologic site investigations are necessary for planning the ground-
water monitoring system and for estimating hydraulic stresses that can act on
the unit so that they can be properly considered during unit design. In
conjunction with existing data, these investigations are used to define:
- The location and extent of aquifers underlying the site. These in-
vestigations define not only the "uppermost" aquifer, but at a mini-
mum the next aquifer below and all underground sources of drinking
water.
- The direction and rate of flow in and between the aquifers.
- The nature of the aquitards, i.e. the geologic barriers to flow
between the aquifers, and their effectiveness in preventing flow.
- Geochemistry of the groundwater in the different aquifers. Knowledge
of the chemistry of the groundwater in the different aquifers prior to
construction of the TSDF unit is necessary to properly evaluate the
results of monitoring the aquifers once the unit is in service.
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Further information on conducting hydrogeologic investigations and on instal-
ling monitoring wells and piezometers may be found in U.S. Environmental
Protection Agency (1983), Fenn et al (1977), Johnson Division (1975), Lutton
et al (1983), EPRI (1985), and Dunnicliff (1988).
7.5 DESIGN OF COMPONENTS OF A LINING SYSTEM
The lining system for waste containment units is made up of a number of
different components. In the context of this document, the term "lining
system" includes the lining materials and all of the materials and components
that comprise the leachate collection systems. For example, the "lining
system" for a new hazardous waste landfill or the lateral extension of an
existing landfill must have:
- A foundation.
- Sidewalls.
- A bottom composite liner.
- A leak-detection system between the top and bottom liners.
- A top liner.
- A leachate collection system on top of the top liner.
Depending on the containment design, a protective soil cover may be placed
above the leachate collection system on top of the top liner. In addition,
various ancillary components, including anchor trenches, sumps associated
with the leachate collection and leak-detection systems, etc., are also a
part of the whole system. Finally, when a landfill is closed, a cover
system needs to be placed over the whole landfill which is also constructed
with a number of different components, including a cap drainage and col-
lection system, cover soil, and venting systems (Lutton, 1986).
This section describes approaches to the design of the various compo-
nents of a lining system with particular reference to the design of a
hazardous waste landfill. It should be noted that the components of a lining
system for a hazardous waste surface impoundment are the same as those for a
hazardous waste landfill except that there is no leachate collection and
removal system above the top liner. This section also discusses ways in
which a choice in designing one component may affect the design of the other
components. The design requirments for hazardous waste contaiment units
proposed in the draft Minimum Technology Guidance documents (EPA, 1985; EPA
1987a) are discussed in detail. Even though most of the information pre-
sented in this section refers to the design of hazardous waste containment
units, much of this information is also applicable to the design of non-
hazardous waste units. Engineering equations for many design problems
dealing with polymeric components and their interaction with various compo-
nents of the lining system have been developed by Richardson and Koerner
(1987).
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7.5.1 Foundation Design
A foundation should provide a structurally stable subgrade for the
overlying components and wastes. Thus, a foundation should resist con-
solidation, differential settlement, and uplift resulting from pressures
inside or outside the containment unit, thereby preventing distortion of
overlying components. In addition, the foundation should provide complete
and integral contact with the overlying liner or other component of the
lining system.
The exact design for the foundation will depend on the geologic, hydro-
logic, and hydrogeologic conditions that exist at the specific site. In
particular, the design is a response to the conditions at the site which may
require special design considerations. The presence of any soil heterogene-
ities should have been observed as part of the site investigation. Settle-
ment analyses may have revealed soils which have significantly different
settlement characteristics which may require removal of some soil or homo-
genization, e.g. collapsible soils which are unsaturated soils that can
experience large settlements when wetted and loaded. The site investigation
may also have revealed soil heterogeneities such as large cracks, sand seams,
sand lenses, and slickensides which may also require special design con-
siderations. The construction of units below the water table (intragradient
facilities) presents problems due to seepage and hydraulic forces on the
liner system.
Goldman et al (1985) report that, given that site topography is fairly
uniform and significant soil heterogeneities are not present, settlement is
usually not a problem for the foundations of a clay liner, e.g. the soil
component of the bottom liner, because most clay liners are sufficiently
thick and elastic to withstand some differential settlement of the foundation
soils. The greater the thickness and elasticity of the clay liner the
greater the tolerance range for differential settlement. However, Goldman
et al (1985) also report that several design engineers recommend excavating
and recompacting the upper 1 to 2 ft of foundation soil to control local
settlement and seepage before installing a clay liner. Some facility com-
ponents, such as footings for pile-type structures used to gain access to
sumps, and underdrain systems which may be required for some facilities, will
require special design considerations to prevent localized settlement under
load.
Seepage into the unit, which can occur in intragradient facilities,
must be controlled. Potential problems associated with the construction of
intragradient facilities are discussed by Goldman et al (1985). An under-
drain system may be necessary where there is a high groundwater table or a
source of water infiltration. Underdrain systems may serve the purpose of
transmitting fluids beneath and through the impoundment site without inter-
action with any contaminants from the containment unit. In addition, an
underdrain (or venting) system may be used to prevent the buildup of gases
underneath a containment unit (see Section 7.3.1.4.3). In the design of
units other than hazardous waste containment units, the underdrain system may
function as a leak-detection system.
7-31
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The basic design of an underdrain or a pressure relief system, which is
similar to that of a leachate collection and removal system, depends on the
intended purpose of the system. For example, a pressure relief system built
underneath a landfill may only be used during construction until the fill
placed on top is capable of counterbalancing uplift forces acting on the base
of the lining system. Thus, no system may be required for collecting and
removing liquids present in the underdrain. The subcomponents of an under-
drain generally include the following:
- A drainage system that allows rapid movement of liquids and/or gases.
- A collection system for conveying what is present in the drainage
medium to points for collection and removal from the underdrain
system, e.g. a sump.
- A system for conveying what is collected by the underdrain system out
from underneath the containment unit, e.g. pumps and closed pipes.
- A system for disposing of what is collected by the underdrain system.
Depending on the function of the underdrain system, the drainage system will
intercept any liquids resulting from leakage or natural drainage or gases
pushing up on the base of the lining system. The drainage system may under-
lie the entire unit, including the sidewalls, or it may underlie one parti-
cular section of the unit, e.g. if the underdrain system is designed to
handle a specific spring, etc. If the underdrain system is intended to
remove liquids that are flowing downwards into the drainage system, the
underdrain system needs to have a base layer of low permeability to allow the
drainage system to collect liquids efficiently. In addition, the drainage
system needs to be sloped to promote the movement of gases (to a venting
system at a high point) and/or liquids (to a sump at a low point). Materials
used in underdrain drainage systems have included select gravel and open-
graded asphalt (Kays, 1986). Measures to prevent the interaction of the
layers immediately above and below the drainage system need to be considered.
For example, a covering layer may be required to protect the overlying liner
(e.g. an FML in a design for a pond for containing nonhazardous liquids) from
penetration by the drainage materials. Materials that have been used include
geotextiles, geonets, graded earth, and coarse sand.
Filters are required where there is a danger of the lining material
fines (i.e. of a clay soil liner) or of the soil underneath the underdrain
working into the drainage system. Granular filters constructed in the
field or geotextile filters can be used. The purpose of the filter is to
stop the migration of particles within the system and simultaneously allow
the uninhibited flow of liquids. The movement of particles into any part
of the underdrain system can, and will, eventually inhibit the acceptable
operation of an underdrain system. Any sign of turbidity in liquid issuing
through the underdrain system could be a sign that the filtering system may
be fail ing.
7-32
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The function of the drainage system is to convey seeping fluids to
collectors, which are generally located in blankets or trenches underneath
the unit. The number of feeding collectors is dependent on the size of the
unit and the basic design of the collection system. Underdrain tile and
perforated pipe have been used for the collection system.
The underdrain monitoring system feeds into a closed pipe system which
needs to be sized to handle more than the expected maximum flow, as any back-
up within the system can cause serious repercussions (e.g. instability of
the embankment). Kays (1986) advised that pipes should terminate in sumps,
channels, drains, or concrete exit structures.
Depending on the function of the underdrain and the containment unit
as a whole, the underdrain monitoring system may be designed to allow any
leakage from the unit to be detected and managed. Some units have pumping
arrangements whereby leakage and underflow are pumped and returned directly
into the unit, while others collect the liquids that are present and dispose
of them off site.
A critical need for an adequate drainage system may exist if ground-
water is present immediately below the unit. A well-designed underdrain
system would minimize or eliminate (1) reverse hydrostatic pressure and (2)
removal of soil from beneath the liner due to groundwater flow. Reverse
hydrostatic pressure occurs when the groundwater level exceeds the operating
water level in the unit. This could occur, for example, during normal
level fluctuations in a drinking water reservoir. The groundwater reverse
pressure can then push on the back side of the lining system, causing liner
failure. Soil may be removed by groundwater flow below a liner, eventually
causing the liner to rupture. If possible, sites where high groundwater
exists should be avoided.
7.5.2 Design of Embankments
The purpose of an embankment in a waste containment unit is to func-
tion as a sloped retaining wall that provides passive restraint to resist the
lateral forces of the stored wastes and to provide support to the overlying
facility components. Embankments can be either aboveground extensions of the
foundation or separate earthwork constructions placed above the foundation.
They must be designed, constructed, and maintained with sufficient structural
stability to prevent their failure. If the overall facility design calls for
a number of units within the facility either to separate different wastes or
to limit the size of an individual unit, embankments can also be used as
walls between the units, thereby creating "cells" within the facility.
Embankments can be constructed of soil material that is compacted as
necessary to a specified strength, unlike soil liner materials which are
compacted for low permeability. Embankments can also be constructed simul-
taneously with the soil liner component in a series of horizontal lifts, as
is shown in Figure 7-8. Materials other than soils can be used to construct
embankments, provided that the embankment design accommodates the properties
of the particular material being used and proper construction procedures are
7-33
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followed. Even though seepage through the embankment should be prevented by
the overlying lining system, drainage layers and structures can be included
in the embankment design because the embankments must be designed to maintain
their integrity even if the lining system fails and seepage occurs.
(a) Horizontal Lifts
(b) Continuous Lifts
Figure 7-8. Methods of liner and sidewall compaction. (Source: Goldman et
al, 1985, p 5-20).
The use of embankments in a containment unit will depend on whether
the unit is constructed above grade, excavated, or a combination of the two.
Above-grade units may be preferred if the costs for constructing embankments
is less expensive than excavation and in cases where the location of the
water table may limit the depth of excavation. In addition, there is less
uncertainty in the design and construction of embankments than there is for
cut slopes because properties of engineered embankments can be more closely
controlled by limiting variations in material type and by uniform compaction
efforts. The natural soil variations that can be present in cut slopes can
result in uncontrolled differential settlement or other problems.
In designing embankments for waste containment units to be lined with
FMLs, the designer must make decisions concerning the following:
- Whether the embankment should be constructed as part of the soil
liner, i.e. in horizontal lifts. Construction in horizontal lifts
results in more stable slopes and allows steeper slopes than con-
struction in continuous lifts. However, many engineers feel that
continuous lift construction results in soil liners of lower perme-
ability (Goldman et al, 1985).
- Whether to include a drainage layer or structure into the embankment,
and if so, what type. Two types include rockfill toes and horizontal
drainage blankets.
7-34
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- How the embankment will be keyed into the foundation.
Preparation of the foundation so that it has adequate bearing capacity
to support the embankment and the overlying system components.
Whether the embankment should be zoned or homogeneous (Figure 7-9).
The requirement for both strong and low permeability material in a
homogeneous embankment can result in a compromise in selecting the
material. Embankments are often designed with zones of materials that
each serve a separate function, e.g. one zone is for the structural
stability of the embankment and another zone is compacted for low
permeability to prevent flow through the embankment.
-Cover Soil
Berm
Top FML
Leachate Collection
and Removal System
toe Drain
Fine-grained Silt
Silt and Clay
FML Component
of Composite Liner
Homogeneous Dike
and Soil Liner
HOMOGENEOUS EMBANKMENT
Not to Scale
.Cover Soil
/TopFML
Leachate Collection
and Removal System
Toe Drain
Coarse-grained
Gravel and/or Sand
FML Component
of Composite Liner
Soil Component
of Composite Liner
Not to Scale
ZONED EMBANKMENT
Figure 7-9. Schematic of homogeneous and zoned embankments for surface
impoundments lined with FML/composite double liners. Slopes of
actual embankments will be less steep.
7-35
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- Selection of the materials for embankment construction. Potential
fill materials for use in the construction of embankments should
be evaluated for several engineering properties, including shear
strength, permeability, settlement behavior, shrink/swell charac-
teristics, and compaction characteristics.
- Slope of the embankments.
-Compaction requirements for the fill material. Actual require-
ments depend on the properties of the selected fill material and
the use of the material in the embankment design. Design specifi-
cations usually specify minimum relative compaction effort (specified
in percent of Standard or Modified Proctor maximum dry density) and
compaction water content. Soils compacted for strength are usually
compacted dry of optimum. The designer may also specify compaction
equipment, number of passes, and/or load energy.
- Runoff diversion to prevent flow into the containment unit. In the
case of a surface impoundment, run-off diversion helps prevent over-
flow, and in a landfill reduces the amount of leachate generated.
- Erosion protection of the outer slopes using berms or vegetation.
- Control of desiccation. In arid regions special designs incorporating
gravel-filled troughs in the embankment crest have been used to
prevent desiccation cracking. If the trough is kept filled with
water, the exposed upper portion of the embankment can be kept moist
(Goldman et al, 1985.
Designing the slopes of embankments and their relation to the design of the
units are discussed in the following paragraphs.
The selection of a specific slope can depend on a combination of factors
including the design limitations set by the use of specific construction
materials including both the fill materials and any materials used to rein-
force the slopes and limitations set by the effect a specific slope will have
on the construction, installation, or performance of the overlying layers.
The use of geogrids and geotextiles to reinforce slopes and intermediate
berms has allowed designers to think in terms of steeper slopes which can
allow for more efficient land use by increasing the capacity of the con-
tainment unit.
Because the friction angle of an FML to a specific soil is lower than
the friction angle of the soil to itself, particularly for HOPE (see Section
4.2.2.5.5), the use of steeper slope angles will affect anchoring of the FML.
In addition, if a soil cover is required to protect the FML, the slope angle
is limited by the angle at which the soil cover begins to slough. If a
granular drainage media, such as sand, is being used in leachate collection
or leak-detection systems that extend up the slopes, the slope angle will be
limited by the angle required to maintain the integrity of the drainage
layer. Synthetic drainage layers on the slopes may require special anchor-
ing.
7-36
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The steepness of the embankment slopes can also affect the ability to
install the various components of a lining system. In installing soil liners
in continuous lifts, Boutwell and Donald (1982) report that a maximum slope
of 2.5 to 1 (horizontal to vertical) is recommended for bulldozer operation
and 2.8 to 1 when sheepsfoot rollers are used. The ability to install an FML
on the slopes will depend on the liner type, the seaming technique, and the
amount of seaming that needs to be performed on the slopes. Relatively heavy
hand-held equipment, such as that used in extrusion fillet welding, may be
difficult to control. The installation of a soil cover on top of an FML can
also be affected. Morrison et al (1981) reports that FML manufacturers
indicated that embankment slopes should be no steeper than 3 to 1 because, in
cases where tracked vehicles were used to push soil cover material up slopes
steeper than 3 to 1, the vehicles had begun to stall, spun their tracks
through the soil cover, and damaged the FML. In the draft Minimum Technology
Guidance document, the EPA suggests that slopes should be no steeper than 3
to 1 (EPA, 1985).
Once a trial slope angle has been selected, slope stability analyses are
performed. A number of computational models are available for analyzing the
stability of embankment slopes. Every slope contains numerous potential
failure surfaces. The end product of an analysis of a given potential
failure surface is the factor of safety (FS), defined as the summation of
driving moments or forces tending to resist failure divided by the summation
of moments or force tending to produce failure. It is necessary to make a
trial and error search for the potential failure surface in the slope having
the smallest FS. The more rigorous methods include the Simplified Bishop,
Spencer, Janbu Simplified, Janbu Generalized, and Morgenstern-Price Methods,
among others. Details of some of the various methods can be found in Lambe
and Whitman (1979), Morgenstern and Price (1965), and Winterkorn and Fang
(1975). In all of these methods, the body of soil within the failure mass is
divided into a number of vertical slices that interact by means of forces
transmitted along the sides of the slices. The methods vary principally in
the assumptions regarding the location and inclination of the side forces
necessary to solve the equations derived for the statically indeterminate
system (Vick, 1983). The greatest source of uncertainty in slope stability
analysis is in obtaining the laboratory-generated shear strength data.
Meyers et al (1986) have developed, under the sponsorship of the EPA, a com-
puter program for the stability analysis of embankments. It is a generalized
program that includes dead loads, live loads, hydrostatic loads, etc., but
not the use of reinforcement "inclusions."
If analysis of the desired slope indicates the need for slope rein-
forcement, the designer can explore the use of geotextiles and geogrids.
Various schemes for the deployment of geotextiles or geogrids in the rein-
forcement of embankments are shown in Figure 7-10. The design process for
reinforcing embankments with geotextiles and geogrids is a direct extension
of soil slope stability analysis using plastic equilibrium concepts common to
geotechnical engineering practice. Consider the soil slope shown in Figure
7-lla without reinforcement, and then the same slope, as shown in Figure
7-llb, reinforced with four layers of geogrid or geotextile. The design for
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(a)
(b)
(c)
(d)
Figure 7-10.
Various geotextile or geogrid deployment schemes for stabiliz-
ing embankments: (a) multiple even-spaced layers in embank-
ments; (b) multiple concentrated layers in embankments; (c)
single layer on top of foundation soil; (d) multiple layers
within foundation soil. (Based on Koerner, 1986, p 109).
each case revolves around taking moments about a hypothetical center of
rotation and forming a factor or safety equation:
- Without reinforcement:
FS =
WX
(7-1)
- With reinforcement:
n
rR + i=1
FS = —
where
wx
FS = factory of safety,
r - shear strength of the soil,
R = radius of failure arc,
W = weight of failure zone,
X = moment arm to center of gravity of failure zone,
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(7-2)
-------
Ti
Yi
allowable strength of geogrid or geotextile,
moment arms to each level of geogrid or geotextile,
and
n = number of reinforcement layers.
0(x,y)
(a) UNREINFORCED SOIL SLOPE
0(x,y)
(b) SOIL SLOPE REINFORCED WITH
GEOGRIDS OR GEOTEXTILES
Figure 7-11. Design approach toward soil slope reinforcement using geogrids
and geotextiles; B = slope angle; H = height.
7-39
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It can easily be seen that the "T-jYi" term can be increased by more layers,
higher strength geogrids or geotextiles, or different positioning, such that
the slope angle (B) or height (H) can be increased drastically over the soil
working by itself. This process is discussed in more detail by Koerner
(1986).
A final comment on the above design should be mentioned as to the allow-
able strength value "T-j". Current practice is to determine the ultimate
strength of the product (geogrid or geotextile) in a wide-width tension test.
ASTM D4595 recommends testing a 8-in. wide test specimen with a 4-in. gage
length. The strength value resulting from a wide-width tension test is then
reduced by a factor of safety against creep and subsequent stress relaxation.
This factory of safety is quite undecided on at this time. Literature gives
recommendations ranging from 2.0 to 5.0 depending on polymer type, manu-
facturing style, and intended application (den Hoedt, 1986). It is felt,
however, that for temporary waste containment facilities the lower end of the
above range is appropriate. Thus values of 2.C to 3.0 are recommended.
Further discussion on the use of geotextiles in slope reinforcement can
be found in Koerner (1986), Fowler (1982), and Rowe and Soderman (1985). The
use of geogrids to reinforce slopes is discussed by Schmertmann et al (1987)
and Wallace and Fluet (1987).
7.5.3 Design of the Bottom Composite Liner
Section 3004(o)(5)(B) of HSWA established Interim Minimum Technological
Requirements until EPA regulations codifying minimum technology requirements
promulagated under Section (o)(l)(A) take effect or the EPA publishes a
guidance document. This section of HSWA states that a liner consisting of at
least a 3-ft layer of recompacted clay or other natural material with an
hydraulic conductivity no greater than 1 x 10~7 cm s'1 is deemed to satisfy
the Interim Minimum Technology requirements for the bottom liner of a double
liner system for hazardous waste landfills and surface impoundments. In the
draft Minimum Technology Guidance document on double liner systems for
hazardous waste landfills and surface impoundments, the EPA requires that
soil bottom liners have a minimum 3-ft thickness and be sufficiently thick so
as to prevent any constituent from migrating through the bottom of the
compacted soil liner for the combined active life and 30-year post-closure
care period of a containment unit, usually a total of 40-50 years (EPA,
1985). Current EPA regulations (as of May 1988) reflect these requirements
(40 CFR 264). However, it is stated in the draft guidance document that the
EPA has "strong reservations" concerning the likelihood that the construction
of a soil-only bottom liner which meets the requirement for preventing
migration is either economically or technically feasible. In addition, in
comparison with an FML/soil composite bottom liner a clay-only bottom liner
can result in a significantly less efficient leachate collection and removal
system between the top and bottom liners and a potentially higher level of
escape from the containment unit (EPA, 1987c; EPA 1987d).
The other alternative for the bottom liner of a double liner system for
hazardous waste containment units is a composite liner consisting of two
7-40
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components, an upper FML component and a lower component of compacted low-
permeability soil. The FML component is required to be compatible with the
waste or leachate to be contained and have a minimum 30-mil thickness. The
soil component of the composite liner is required to be at least 90 cm (36
in.) of emplaced (i.e. in situ soils used to construct a liner must be
excavated and then placed back in lifts with a maximum thickness of 6 in.
after compaction), compacted, low-permeability soil with an in-place satu-
rated hydraulic conductivity of 1 x 10"? cm s~l or less.
This section discusses design considerations for the soil and FML
components and also discusses requirements for the interface between the two
components.
7.5.3.1 Design of the Soil Component--
Soil liners are constructed of compacted soils and are installed in a
series of lifts of specified thicknesses. The compacted liner must have
sufficient thickness and strength to provide structural support to overlying
facility components. In the case of soil liners used as the lower component
of a composite liner, the soil component serves as a protective bedding
material for the FML upper component and minimizes the rate of leakage
through any breaches in the FML upper component. The present draft of the
Minimum Technology Guidance document on double liners for hazardous waste
landfills and surface impoundments requires soil liners used as the lower
component in the bottom liner of a double liner to be at least 90 cm (36 in.)
thick and have an in-place saturated hydraulic conductivity of 1 x 10~'
cm s'1 or less (EPA, 1985). Soil liners associated with the management of
nonhazardous materials may have different thickness and permeability require-
ments; for the purposes of this discussion, a maximum saturated hydraulic
conductivity requirement of 1 x 10"^ cm s~l is assumed.
In considering a particular soil as a lining material, the most im-
portant characteristic is low permeability to water and to dissolved in-
organic and organic species. Other characteristics include the tendency of
the soil to interact with constituents of the waste liquid to be contained,
the ability of the soil to attenuate constituents of the waste liquid, and
the strength of the soil liner before and after contact with constituents of
the waste liquid, the amount and type of compactive effort required to
achieve the density associated with the required permeability, and the range
of moisture contents at which the soil can be compacted to achieve the
required permeability.
This subsection briefly discusses some aspects of the design of a soil
liner with particular reference to permeability and the relationship between
soil properties and permeability. Also discussed are some aspects of select-
ing a soil for use as a lining material, the specifications of a soil liner,
and the importance of inspecting construction and verifying design specifi-
cations by performing field permeability testing, e.g. on a constructed test
fill. Goldman et al (1985) discuss the design of clay liners in more detail.
7-41
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7.5.3.1.1 Soil permeability—The permeability coefficient of a soil is
a measure of the ability of a soil to transmit a particular liquid and is one
of the most important geotechnical characteristics of a soil, particularly of
a clay soil. This coefficient represents a rate movement for a unit volume
of fluid per unit cross-sectional area perpendicular to the flow direction
and normalized per unit gradient. For systems in which water is the permeat-
ing liquid, the permeability coefficient is usually called hydraulic con-
ductivity. This coefficient is derived from Darcy's equation. Most of the
technical information that has been developed, particularly by engineers, to
describe saturated flow through porous media, i.e. through soils, uses
Darcy's equation. As is discussed in Section 3.3.2, Darcy's equation states
that the flow rate, Q, is proportional to the hydraulic gradient, i, (i.e.
the difference in hydraulic head divided by length) as follows:
Q = kiA , (7-3)
where
Q = the rate of flow (cm^ cm~2 s~l),
k = a constant, also known as Darcy's coefficient of permeability
(cm s'1),
A = the total cross-sectional area normal to the flow (cm^), and
i = the hydraulic gradient (cm cm~l).
Darcy's equation reflects the idealizations that the gradient is so signi-
ficant in determining the flux Q that it masks the importance of other
influences (such as difussion) and that flow is proportional to total cross-
sectional area of flow, which includes both solid particles and voids. The
principal postulate is that the permeability coefficient k is constant; that
is to say, there is a linear relationship between gradient and flux, which
has been shown to exist for many soils. The validity of Darcy's equation,
however, has been questioned for some clay soils, where it is believed that
the physical properties of the pore liquid can be altered by proximity of the
liquid and the soil matrix. In addition, the permeability coefficient k of
some clay soils can be changed by a sufficient increase of gradient to cause
separation and migration of clay particles, which subsequently plug some
pores that might conduct flux.
Despite its limitations, Darcy's equation is the relationship most
frequently used to describe the water flow in soils, particularly for firm
soil structures, i.e. those that are neither affected by the magnitude of the
pore-water pressure and the gradient, nor affected by osmotic and swelling
effects. Qualitatively, Darcy's equation is always applicable, since the
flux increases with hydraulic gradient.
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7.5.3.1.2 Relationship between soil properties, compactive behavior,
and permeability--The permeability of a compacted soil depends on two groups
of factors. The first group includes all the intrinsic properties of the
particular soil that determine its potential for remolding and compaction,
such as clay proportion, clay particle-size distribution, clay mineralogy and
physical chemistry, and soil gradation. These intrinsic properties control
the relationship between compactive effort and density at different moisture
contents, i.e. the compactibility of a soil. The second group includes the
various conditions during compaction (e.g. moisture content, load size, mode
of application, and thickness of the lift) which also affect the permeability
of the resulting soil liner.
Clay Content and Hydraulic Conductivity—Clay soil particles are flat,
platelike shapes varying in thickness from 10 to 500 A, while their length
and widths are significantly larger. The flat surfaces of the particles are
highly negatively charged by virtue of their geologic formation processes.
This negative charge attracts water molecules (and also partially hydrated
cations) to form an adsorbed water layer around the particle itself. Col-
lectively this adsorbed water on all of the clay particles gives it its
plasticity or slippery feel. The adsorbed water layer is actually many
layers thick and extends well into the soil's voids rendering the clay soil
itself quite poor in its ability to conduct water.
The hydraulic conductivity of most undisturbed soils ranges from 10~?
cm s~l to 10~3 cm s~l. The particle-size distribution seems to be the most
significant characteristic over the whole range of conductivity values
of undisturbed soil. Soils with more than 25-30% clay-size particles are
concentrated in the lower range of conductivities, i.e. 10~7 cm s~l to
10~5 cm s~l. If, however, k is correlated with the percentage of clay-size
particles over this range of values, the relationship between particle size
and hydraulic conductivity becomes less significant.
Given a relatively high percentage of clay-size particles in a specific
soil, properties other than the percent clay content are more significant
determinants of its flow properties: the types of clay minerals in the clay
fraction, the interlayer chemistry of the crystal-unit, the susceptibility
of the particles to disperse or flocculate upon hydration and/or mechanical
remolding, and the average size of a typical tactoid (an agglomerate of clay
particles).
The three groups of clay minerals, in order of decreasing permeability,
are:
- Kaolinites.
- Illites.
- Montomorillonites (including smectites and bentonites).
The predominance of one or the other of these minerals in the clay fraction
will affect soil-water flow characteristics and interaction of the soil with
7-43
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the permeating liquid. All of these variables have great effects on soil-
water flow characteristics, and can cause permeability to vary by up to two
orders of magnitude for soils that are otherwise apparently similar.
Clay Soil Structural Arrangements—The structural arrangement of soil
the density and thus also the perme-
presents three types of clay particle
understanding their behavior. These
particles is important in determining
ability of a given soil. Figure 7-12
arrangements which are significant in
types include:
- Dipsersed or parallel arrangements. In this type of arrangement, the
clay particles are parallel to one another and their relative close-
ness gives rise to their density. Note that given this type of
arrangement, the soil is anisotropic, i.e. that the hydraulic con-
ductivity will be very different in different directions.
Low Density High Density
(a) Dispersed, or Parallel, Type
Low Density High Density
(b) Flocculated Type
Low Density High Density
(c) Random, or Cardhouse, Type
Figure 7-12. Types of clay particle arrangements,
7-44
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- Flocculated arrangements. In this type, numerous dispersed particle
groups gain sufficiently in mass and arrange themselves in floes which
settle collectivley.
- Random or cardhouse arrangements. The clay particles in this type are
arranged edge to face in a random fashion. Note that given this type
of arrangement, the soil is isotropic, i.e. that there is no prefer-
ential direction for the conductivity of water.
Dispersed and random arrangements are seen in field compacted (hence re-
molded) clay soils, whereas flocculated arrangements are not.
Compacted Behavior of Clay Soils — As originated by Proctor in the 1930's
and standardized by ASTM as D698, laboratory compaction tests compact the
target soil in a standardized mold in a prescribed number of layers at a
given compactive effort. The compactive effort is determined by the weight
of the hammer, the number of layers, and the number of blows per layer. The
soil is at a given water content and results in a measured unit weight (or
wet density). The test is repeated at a number of different water contents
(usually starting low and successively going higher) which results in a set
of water contents and wet densities. Using the formula,
+ w), (7-4)
where
y^ - dry density,
>t = total (or wet) density,
w = water content, and
the corresponding dry densities are calculated and plotted versus water
content. Figure 7-13a presents typical relationship between density and
water content resulting from a compaction test. The "optimum water content"
is the water content at which the maximum density is achieved, given a
specific compactive effort. Note that the soil only approaches 100% satur-
ation but never meets it, since some air is usually trapped in the soil
during placement. Also note that the structure of the clay goes from random
(due to lack of water), to dispersed (at the maximum density), to a low-
density dispersed (due to excessive water). Figure 7-13b shows how the
relationship between density and water content shifts with different com-
pactive efforts.
Moisture Content and Field Placement of Clay Soils --Specifications
for compaction of clay soils in various earthwork projects revolves around
achieving a minimum dry density which is a percentage of the maximum dry
density (Ydmax)- Often 90 to 95% of a given method, e.g. Standard or
Modified Proctor, will be stated as the required value. As can be seen in
Figure 7-14, for a particular compactive effort (e.g. Standard Proctor), the
7-45
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water content at which the required density can be achieved now becomes a
range. The soil described in Figure 7-14 has a maximum density of 115 Ib/cu
ft. Given a required density of 90% maximum density, which is equal to 103.5
Ib/cu ft, the required water content ranges from 10 to 28%.
5
100% Saturation Curve
Water Content (w)
(a) BASIC COMPACTION RESPONSE OF CLAY SOIL
I
High CE
100% Saturation Curve
Water Content (w)
(b) EFFECT OF COMPACTIVE EFFORT (CE)
Figure 7-13. Compaction response of clay soils,
7-46
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130
120 -
110
.o
£ 100
O)
D
80
70
,'J
Range ol Acceptable ^
Water Contents
For 90% Td max
Specifications
'
=20%
wmax = 28%
10 20 30
Water Content (w),%
40
50
Figure 7-14. Water content range for achieving a density value related to
considerations depending on the compaction response of a
soil.
From a contractor's point of view, it is less problematic to compact
clay soil at the lower end of the required water content range because it
is easier to add water to a fill than it is to remove it. Thus, if precipi-
tation occurs during construction of a site which is being placed at the
lower end of the required water content range, the additional water may not
result in a soil water content greater than the required range. Conversely,
if the site is being placed at the upper end of the range, e.g. at 25%, any
additional moisture will be excessive, resulting in a water content over 28%
and making the 90% 7^ unattainable. Under such conditions, the contractor
must wait, aerate the soil with disc harrows and road graders, and hope for
sun, all of which result in scheduling delays and increased costs. Neverthe-
less, it should be noted that this discussion has focused on density and not
on hydraulic conductivity, which is the most important property of soil
liners for waste containment units.
7-47
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There are numerous studies on the influence of clay type, clay struc-
ture, and density on hydraulic conductivity. For the purpose of this discus-
sion it can be said that the higher the dry density for a given soil, the
lower the permeability coefficient. Figure 7-15, shows the relationship
between the void ratio (which is the ratio of the volume of void space to the
volume of solid particles in a given soil mass and, hence, inversely related
to density) and permeability, which changes by orders of magnitude depending
on the void ratio. It can also be seen that, for two clay soils, the res-
ponse curves are very different.
2.8
TO
cc
2.4 -
2.0
1.6
1.2
0.8
0.4
Soill
Soil 2
_J—L.
I 111
10'
10'
10
-7
k, cm
Figure 7-15.
Relationship between hydraulic conductivity and the void ratio
for two soils. (Based on Olsen and Daniel, 1981).
However, particle arrangement can also have a significant effect on
permeability. It seems intuitively more advantageous for a soil liner to
have a dispersed clay structure in order to retard vertical moving liquids;
thus, given the relationship between water content and particle arrangement
presented in Figure 7-13a, wet of optimum conditions are preferable to dry
of optimum. Hhen these permeability considerations are added to the dif-
ficulties presented by soil "clods" which appear when clay soils are placed
dry of optimum, it seems that wet of optimum is a technically-sound approach
to obtaining a low j_n situ hydraulic conductivity for a clay soil. Some
engineers presently recommend compacting soils at a water content 3 to 6%
wet of optimum. Note, however, that placement wet of optimum can pose
problems and that the contractor will always be challenged by inclement
weather.
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7.5.3.1.3 Selection of soil for use as a lining materia1--0ne of the
most important design activities associated with the construction of a soil
liner is selecting a soil. During the site investigation, the on-site soils
should have been tested for various properties including compactibility,
chemical sensitivity (e.g. compatibility with the waste to be contained).
Tests for these properties are discussed by Haxo et al (1987), Spigolon and
Kelley (1984), and Goldman et al (1985). The results of these tests may
indicate a range of soil moisture contents following a specific compaction
procedure and a range of soil densities for which the corresponding soil
permeability coefficient is below the required maximum hydraulic conductivity
value, i.e. 1 x 10~? cm s~l for the bottom component of a composite bottom
liner for a hazardous waste landfill or surface impoundment. Examples
of what the designer may face in comparing soil compaction data with soil
permeability data include the following situations:
- Case 1: For an idealized soil, there is a broad range of moisture
contents (w) and of soil dry density (T^) for which the permeability
coefficient (k) is less than the maximum allowable (Figure 7-16).
Moreover, the range of moisture contents which can result in the
minimum dry density necessary to achieve required permeability coef-
ficient corresponds to the range of the moisture contents which
results in acceptable permeabilities. This is expressed by a unique
relationship between 7^ and k. This situation is the safest pos-
sible because there should be no problems in optimizing the moisture
content and corresponding density of the soil during compaction. In
addition, over-compaction will not damage the permeability charac-
teristics of the resultant soil liner.
- Case 2: For an idealized soil, there is a range of moisture contents
(w) for which the permeability coefficient (k) is less than the
maximum allowable (Figure 7-17). However, in this case, the cor-
responding range of densities is in absolute terms on the low side,
and compaction to maximum density will not result in a liner that
meets the requirement for hydraulic conductivity. The soil in this
example achieved a state of low permeability, not because of densi-
fication, but because of shear deformation and particle orientation.
Even though the soil may be compacted within the necessary moisture
content range to achieve the required conductivity values, it would
be risky to rely on the stability of this structure with time. Thus,
this particular soil is probably not suitable for use as the clay
component of the bottom composite liner in a double liner system.
- Case 3: The soil cannot be compacted so as to achieve the required
conductivity value, indicating that this soil is not acceptable for
use as the clay component of a bottom composite liner.
If the on-site soils are not acceptable for use in constructing a soil liner,
borrow sources may need to be identified and investigated. The possibility
of constructing a soil liner by blending the on-site soils with clay addi-
tives can also be explored.
7-49
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W
0)
Q
Moisture Content (w)
c
0>
0)
Maximum Allowable
Hydraulic Conductivity
Optimum Moisture
Moisture Content (w)
o
O
s
m
o>
0.
Both Dry and Wet of Optimum
1 Maximum Density
Soil Dry Density (7d)
Figure 7-16.
Schematic representation for Case 1 of the relationships
between soil dry density, soil moisture content, and perme-
ability coefficient for an idealized soil with no particle
orientation when compacted at high compactive effort.
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8
Moisture Content (w)
0>
3
Maximum Allowable
Hydraulic Conductivity
Optimum Moisture
Moisture Content (w)
^
I
I
£
Dry-of-Optimum
-Maximum Allowable
Hydraulic Conductivity
Maximum Density
(Tdmax)
Soil Dry Density (Td)
Figure 7-17.
Schematic representation for Case 2 of the relationships
between soil dry density, soil moisture content, and perme-
ability coefficient for an idealized soil.
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This discussion only indicates some of the factors involved in evaluat-
ing selecting of a soil for use as a soil liner. Other factors include the
compatibility of the soil liner with constituents of the waste to be con-
tained, shrink/swell behavior, etc. Present EPA policy requires assurance
that the soil materials used in constructing a liner for a hazardous waste
containment unit are compatible with the waste to be contained (EPA, 1986d).
The test method recommended to verify compatibility is EPA Test Method 9100
(EPA, 1986c), which determines the effect of the leachate or waste liquid to
be contained on the hydraulic conductivity of the compacted soil. It should
be noted that Method 9100 is currently (June, 1988) under review. Further
discussion on soils as liner materials can be found in Haxo et al (1987) and
Goldman et al (1985).
7.5.3.1.4 Design and specifications for a soil liner--0nce a soil has
been selected for use in constructing a soil liner, the other important de-
sign activities are associated with specifying the parameters for construc-
tion. The design specifications, based on the information developed during
the site investigation and in the process of selecting the soil, must provide
the contractor who performs the construction with the information necessary
for constructing a soil liner, including any special procedures for the
different soils that may be present so that the end result will be a uniform
soil liner. These specifications need to be stated in terms of the perform-
ance required from the soil liner and in terms of methods of achieving the
required performance. The basic performance requirement is low hydraulic
conductivity. Specifications for constructing a soil liner can include the
following:
- Overall thickness of the soil liner. In the draft Minimum Technology
Guidance document on double liner systems for hazardous waste land-
fills and surface impoundments, the EPA requires the soil component
of a bottom liner to be at least 90 cm (36 in.) in thickness after
compaction (EPA, 1985).
- Required density, usually expressed as a percentage of a maximum
dry density obtained by a specific method, e.g. 90 or 95% Proctor.
- A soil moisture content necessary to achieve the required density,
usually 2 to 3% wet of optimum; some engineers are presently recom-
mending 3 to 6% wet of optimum.
- Maximum clod size.
- The depth of the unit-layer to be compacted at one time, i.e. lift
thickness. In the draft Minimum Technology Guidance document on
double liners systems for hazardous waste landfills and surface
impoundments, the EPA recommends that the liner be compacted in
lifts not exceeding 15 cm (6 in.) after compaction to maximize the
effectiveness of compaction throughout the lift thickness (EPA,
1985).
- Measures to be taken for tying together the lifts, e.g. scarification.
7-52
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- Number of passes of the compacting equipment over one unit-layer.
- Type of compacting equipment.
- Weight of the compacting equipment.
- Trade-name and model of the compacting equipment, if applicable.
- Method of constructing the sidewall. In the draft Minimum Tech-
nology Guidance document on double liners systms for hazardous waste
landfills and surface impoundments, the EPA recommends constructing
the liner in lifts parallel to the slope in order to minimize flow
between the lifts (EPA, 1985). However, some design engineers feel
that construction of the liner in horizontal lifts can result in an
acceptable liner. In this method of construction, the sidewalls
are overbuilt and trimmed back to the specified slope. Special care
is required to ensure that adjacent lifts are tied together properly.
In addition, some engineers who advocate sidewall construction in
horizontal lifts also place a prefabricated bentonite liner on top of
the soil liner.
Because of soil variability and the scale of the operation in designing
and constructing a soil liner, some flexibility must be provided by the
designer in the construction specifications. If it were the case that the
top layer of soil used in constructing a liner had a uniform moisture content
and density characterization in the undisturbed state, then the working
procedures indicated in the design specifications for a particular soil unit
normally would be easy to observe. In addition, heterogeneity of soil is the
rule rather than the exception, and more than one soil unit may be used in
constructing the soil liner. Thus, two important features of constructing a
soil liner are inspection of both the workmanship and the soil material being
used in construction and the ability to modify construction practices as the
need arises. Inspection is performed to monitor the quality of the work
being performed and to verify that the design requirements are being met
(e.g. compaction at proper moisture content or to the specified density).
Inspection is also performed to verify the accuracy of the results of the
site investigation on which the design specifications are based. Often there
can be soil heterogeneities that escaped observation during the site or
borrow source investigations. Depending on the results of the QA/QC in-
spections, the designer may be required to modify the design specifications
in order to achieve the required hydraulic conductivity.
7.5.3.1.5 Field verification of design specifications—Present EPA
guidance on the construction of hazardous waste containment units recommends
the construction of a test fill to verify that the specified soil density,
moisture content, and permeability values can be achieved consistently in
constructing the full-scale unit (EPA, 1985; Northeirn and Truesdale, 1986).
Constructing a test fill before constructing the actual soil liner can
minimize the potential dangers and expense of constructing an unacceptable
liner. The test fill is constructed using the same soil, equipment, and
7-53
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procedures that are specified for the construction of the actual liner. The
data resulting from constructing the test fill, including documentation of
actual construction and the results of all QA/QC testing, need to be well
documented in accordance with good engineering practice.
In particular, the test fill is a convenient method for evaluating the
most critical requirement for a compacted soil liner—low hydraulic con-
ductivity. Several studies have indicated that in-place measurements of
hydraulic conductivity are more trustworthy than laboratory tests for
determining the hydraulic conductivity of soil liners because the soil volume
being tested can be quite large and because there is only minimal disturbance
of the soil material during testing (Herzog and Morse, 1984; Gordon and
Huebner, 1983; Daniel, 1984; Boutwell and Donald, 1982). Daniel (1984)
reported a case in which the rate of leakage through a pond liner was ap-
proximately 1,000 times greater than that predicted from laboratory hydraulic
conductivity measurements on both undisturbed and recompacted samples. A
field hydraulic conductivity test which used an 8-ft diameter ring and which
was run for four weeks resulted in a hydraulic conductivity value that was
within the range calculated from the actual leakage rate. These results are
summarized in Table 7-2. The large discrepancy between the laboratory and
field generated data was felt to be caused by the presence of large clods in
the compacted soil which allowed flow within the relatively large pathways.
In general, reasons for a higher than expected hydraulic conductivity of a
soil liner have been related to the presence of macrofeatures (such as
desiccation cracks, weathering discontinuities, and root-holes), and the
inadequate control of field compaction parameters, including density, water
content, soil type, and placement procedures. The presence of these macro-
features in a soil liner would tend to result in a higher quantity of liquid
flow than would be predicted from laboratory tests.
TABLE 7-2. SUMMARY OF HYDRAULIC CONDUCTIVITY
MEASUREMENTS AT SITE IN CENTRAL TEXAS
Hydraulic conductivity
Type of Test (cm s~l)
Laboratory hydraulic conductivity test 5 x 10~10 to 8 x 10~7
Field hydraulic conductivity test 4 x 10"5
Back-calculated from actual leakage rate 2 x 10"5 to 5 x 10~5
Source: Daniel, 1984.
The two types of tests that have been proposed as field hydraulic
conductivity tests use either lysimeter pans or infiltrometers. The test
fill design described by the EPA Technical Guidance document on the CQA for
hazardous waste containment units includes a free-draining underdrain system
7-54
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equipped with a lysimeter pan for collecting and quantifying seepage through
the test fill liner (Northeim and Truesdale, 1986, pp 21-23). The major
objection to this type of test as a CQA test is the length of time that would
be required to verify an hydraulic conductivity of 1 x 10~7 cm s~l or less.
Several types of infiltrometers have been developed as methods of
measuring in-place hydraulic conductivity, which is calculated from the
infiltration rate. The infiltrometer that appears to have the most promise
for verifying hydraulic conductivities less than or equal to 1 x 10~7 cm s'1
is the sealed double-ring infiltrometer (SDRI) developed by Daniel and
Trautwein (1986), which is a modified version of the infiltrometer used in
ASTM D3385. Double-ring devices are designed to restrict the amount of
lateral spreading of liquid originating from the inner ring, allowing seepage
to be considered essentially one-dimensional. In comparison with the D3385
infiltrometer, which is unsealed, the SDRI allows greater precision in
determining small changes in water level and has greater control over evapo-
rative loss. To determine the hydraulic gradient, which is necessary for
calculating the hydraulic conductivity of the liner from the infiltration
rate, the test can continue until the wetting front reaches the base of the
liner (assuming the water pressure is zero at the base of the liner) or
tensiometers can be used if porous probes at different depths are attached to
a differential pressure gauge or manometer.
In comparison with laboratory CQA tests, field hydraulic conductivity
tests have several disadvantages including their duration, the effort in-
volved in monitoring and maintaining test conditions, and concerns about the
exact volume of soil being tested. The duration of field tests can result in
substantial delays in construction. In addition, the use of infiltrometers
has been criticized because of:
- Difficulties in achieving saturated flow conditions within the rel-
atively limited time alloted to performing infiltrometer CQA tests.
- Concerns about the accuracy of gradient values used to calculate
hydraulic conductivity, particularly at the beginning of tests when
soil suction may cause a high rate of infiltration and result in a
calculated hydraulic conductivity that is too high.
- Concerns about the effect of not confining the soil tested by the
infiltrometer on the rate of infiltration, particularly for highly
plastic soils. The normal stress on a test fill can be negligible in
comparison with normal stress levels caused by waste loadings in
actual landfills and surface impoundments.
If field hydraulic conductivity testing of the test fill is specified as
the method of verifying that the construction and material specifications
result in a liner with the required hydraulic conductivity, the results of
the field hydraulic conductivity test need to be correlated with the con-
struction parmeters (e.g. compactive effort, maximum clod size) and the
results of potential surrogate tests. Even though field permeability testing
7-55
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could be performed on the full-scale liner, such testing would result not
only in substantial construction delays but would probably result in damage
to the liner as a whole due to prolonged exposure to natural weathering.
Thus, tests need to be selected that can be applied to the full-scale liner
as surrogates for field hydraulic conductivity tests. Surrogate tests are a
group of tests that do not actually measure field permeability but whose
results, when considered together, can be used to estimate field hydraulic
conductivity and, hence, can be used to control this parameter during low-
permeability soil liner construction. If surrogates for field hydraulic
conductivity tests are to be used with a high degree of confidence, data
obtained from a test fill evaluation need to show the relationships between
the hydraulic conductivity as measured by the field test of areas and lifts
across the test fill and the proposed surrogate test results. Examples of
potential surrogate tests include hydraulic conductivity of laboratory
compacted soil samples, hydraulic conductivity of undisturbed samples,
Atterberg limits, particle-size distribution, compacted moisture content,
compacted soil density, and penetrometer strength tests.
Guidelines for constructing a test fill are discussed by Northeim and
Truesdale (1986).
7.5.3.2 Design of FML Component of Bottom Composite Liner--
The purpose of an FML in a waste containiment unit is to control the
migration of any mobile constituents out of the unit during the period that
the unit is in operation and during the post-closure care period. In order
to fulfill this function, the FML has to meet the following requirements:
- The FML must have sufficiently low permeability to the constituents
of the waste to be contained so that escape from the unit is below a
level that may pose a danger to human health or the environment.
- The FML must be chemically compatible with all constituents of the
waste to be contained, i.e. the waste must affect neither the FML nor
the seams in such a way that the FML is no longer able to fulfill its
function.
- The FML must be mechanically compatible with its service conditions.
- The FML must be sufficiently durable to maintain its integrity in the
service environment through the end of the post-closure care period.
- The FML must be capable of being installed under a sufficiently broad
range of environmental conditions; in particular, the FML must be
capable of being seamed in such a way that the seams approximate the
strength and durability of the FML itself.
This section discusses these performance requirements, and describes the
factors involved in selecting an FML and ways in which the choice of a
particular FML may affect the unit design. Design of the FML layout and
design considerations involved in attaching the FML to penetrations and
appurtenances are also discussed.
7-56
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7.5.3.2.1 Performance requirements of an FML--In order to function as
a liner in a TSDF containment unit, an FML must meet performance requirements
for a wide range of properties, including permeability, chemical compati-
bility, mechanical compatibility, and durability. These properties are
discussed in Section 4.2.2.4. The mechanisms of transport through an FML are
discussed in Chapter 3. The seaming of FMLs is discussed in Section 4.2.2.3.
These performance requirements, various ways in which these requirements can
affect selection of a particular FML, and the minimum technology requirements
proposed in the draft Minimum Technology Guidance document on hazardous waste
landfills and surface impoundments (EPA, 1985) as ways of meeting these
performance requirements are discussed in this subsection.
7.5.3.2.1.1 Low Permeability. The primary function of an FML in a
TSDF containment unit is to minimize or control the flow of mobile constit-
uents out of the unit and prevent them from entering the environment,
particularly the groundwater. In order to do this, the installed FML must
have sufficiently low permeability to all constituents of the waste to
be contained such that the level of transmission through the FML does not
pose a threat to human health or the environment. It should be noted that
transmission level for a particular constituent which can pose a threat to
human health or the environment is specific to the site, the constituent's
toxicity, and the mobility and biodegradability of the constituent.
Transmission of liquids and soluble waste constituents through an
installed FML can occur because of permeation through the FML on a molecular
basis or because of discontinuities (e.g. holes) in the sheeting or the
seams. Thus, an FML should be free of pinholes, blisters, holes, con-
taminants, and any other imperfections that can result in a discontinuous
membrane. It should also be noted that, in order to allow only the minimum
level of transmission, an FML needs to be capable of being installed in such
a way that there is 100% seam continuity, needs to be mechanically compatible
with the other components of the lining system, and needs to have sufficient
durability to continue to function after long-term exposure.
As is discussed in Chapter 4, continuous FMLs do not appear to be
permeable by ions with the possible exception of hydrogen ions. In addition,
flaw-free FMLs cannot be permeated by liquids per se; however they can be
permeated by liquids, gases, and vapors on a molecular level, depending on
the solubility of the permeating species and its diffusibility in the mem-
brane. A concentration or partial pressure gradient across the FML is the
driving force for the direction and rate of transport. The individual
species migrate through the FML from higher to lower concentration. The
permeation mechanism for transport through a nonporous membrane is discussed
in Chapter 3, the transmission of organics through FMLs in Section 4.2.2.4.1,
and the transmission of organic mixtures and of organics in aqueous solutions
through FMLs in Section 5.4.1.6. The results of the studies reported in
these sections indicate the following:
- The transmission of an individual species can vary from polymer to
polymer.
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- The transmission of several species through a single FML can vary over
several orders of magnitude.
The presence of other permeating
of a species through an FML.
species can affect the transmission
- The permeation rate through an FML of an organic in an aqueous solu-
tion can be substantially higher than what would be expected from the
difference in concentration because of selective permeation.
The specification of a maximum transmission level through an FML can
affect the choice of a generic FML type and a specific composition, particu-
larly if organics are present in the waste liquid. The requirement can also
affect the selected thickness because, given a specific composition, trans-
mission rates are related to the thickness of the polymeric membrane. In the
case of fabric-reinforced FMLs, it should be noted that transmission rates
are related to the thickness of the membrane and not the overall thickness,
which includes the thickness of the fabric reinforcement.
C h em i c a1 C omp at i b i1i ty.
7.5.3.2.1.2
the FML must be compatible with the waste
maintain its low permeability and mechanical
waste so that it can continue to function
need to be compatible with the waste liquid.
FML with a waste liquid can result principally
In order to function as a liner,
to be contained, i.e. the FML must
properties after exposure to the
as a liner. The seams also
Chemical incompatibility of an
because of the following:
- Absorption of large amounts of waste constituents.
- Extraction of components of the original FML compound.
Chemical stresses are discussed in Section 5.3.1.
The EPA has developed Method 9090 (EPA, 1986c) as a method for assessing
the chemical compatibility of waste liquids and FMLs. Method 9090 is pre-
sented in Appendix L. This test attempts to simulate some of the conditions
that an FML may encounter in service and to determine the effects of contact
with a waste liquid on an FML. In this test, slab samples of candidate FMLs
are immersed for up to four months at 23° and 50°C in a representative sample
of the waste liquid which will contact the in-service FML. Physical and
analytical tests are performed on the unexposed FML for baseline data and on
samples exposed to the waste liquid for 30, 60, 90, and 120 days. Thus, the
test involves many steps including selecting representative samples of both
the waste to be contained and an FML, exposing the FML samples to the waste
under highly controlled conditions, testing the unexposed and exposed FML
samples for physical and analytical properties, and interpreting the final
results. Factors that can influence Method 9090 test results are discussed
in Section 5.4.3.
7-58
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The draft Minimum Technology Guidance document states that the EPA
considers significant deterioration in any of the properties measured on
samples exposed in a Method 9090 test to be evidence of incompatibility (EPA,
1985). Quantification of levels that indicate significant deterioration,
however, are not available. At the present state-of-the-art of FML tech-
nology and the design and construction containment units for TSDFs, it is not
possible to set minimum test values which correlate with ultimate perform-
ance. Thus, there are no established or accepted benchmarks of FML perform-
ance based on immersion tests, and professional judgment is still necessary
for interpreting the significance of Method 9090 test results.
Computer programs based on expert systems are being developed by the
EPA to assess data from Method 9090 compatibility tests (Rossman and Haxo,
1985). These systems are designed to provide assistance to those responsible
for evaluating Method 9090 test results. One such system, called FLEX (which
is an acronym for Flexible Liner Evaluation Expert) is available in a draft
form from the Hazardous Waste Engineering Research Laboratory (HWERL) of the
EPA. FLEX is intended as a screening tool geared for use by those familiar
with FML testing and EPA Method 9090. The system can rapidly pinpoint in-
consistencies in the test data and test results which suggest that the liner
is substandard or incompatible. However, the recommendations resulting from
an analysis by FLEX should not be considered absolute; they are to be used
only as a guide by a permit reviewer.
The requirement for chemical compatibility affects the choice of FML
type and composition more than any other consideration, particularly if
organics are present in the waste to be contained.
7.5.3.2.1.3 Mechanical Compatibility. An FML used to line a TSDF unit
must be able to maintain its integrity after exposure to mechanical stresses.
Short-term mechanical stresses can include stresses during installation such
as those caused by placement of a granular drainage layer and the traffic of
heavy equipment, stresses caused by thermal shrinkage, and stresses related
to the weight of the materials placed on top of the liner system. Long-term
mechanical stresses are more often the result of the materials on top of the
liner system or differential settlement of the subgrade. Tests that have
been developed to simulate field mechanical stresses are discussed in Section
5.5.
At present, no correlations have been developed between properties
measured by standardized methods (e.g. uniaxial tensile strength, biaxial
burst strength, tear resistance, etc.) and the ability of an FML to function
as a component of an engineered system. Thus, no minimum values for these
properties have been established. Appendix K presents suggested specifi-
cations for selected FMLs. These specifications represent an index of the
quality of the FML compound and/or construction and are similar to purchase
specifications; however, they are not performance specifications.
There must be adequate friction between the FMLs on the slope and the
soil and components of the leachate drainage and collection systems to ensure
7-59
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that no slippage or sloughing may occur. The low friction angles of some
FMLs with respect to soils and other materials must be taken into account in
the design (Section 4.2.2.5.5). Friction angles are considered by Richardson
and Koerner (1987) in design equations to evaluate:
- The ability of an FML to support its own weight on the side slopes.
- The ability of an FML to withstand shear stresses of the waste after
filling.
- The anchor capacity of an FML placed in various anchorage configu-
rations.
- The stability of a soil 'drainage layer or geonet on top of an FML.
Various textured FMLs are being developed by different manufacturers to
increase the friction between the FML and soils. It should be noted that
textured FMLs, specifically polyethylene, pose difficulties for specifi-
cation, testing, installation, and seaming.
Considerations about mechanical compatibility can affect choice of FML
type and construction. In addition, since in the case of unreinforced FMLs
absolute mechanical properties are related to thickness, concerns about
mechanical compatibility can also affect choice of a specific thickness.
7.5.3.2.1.4 Capability of Being Installed. An FML used to line a TSDF
containment unit must be capable of being installed in such a way that it can
form a continuous durable membrane. The ability to form a continuous durable
membrane is dependent on the ability of the material to be seamed. A major
reason for the tendency in recent years not to use cross! inked FMLs is the
difficulty encountered in seaming these FMLs. In addition, if an FML tends
to become brittle at colder temperatures and becomes particularly sensitive
to damage caused by winds, this type of FML will be difficult to install.
Some unreinforced thermoplastic FMLs (e.g. PVC or CPE) may become difficult
to handle on hot sunny days due to softening and shrinkage caused by the
increased surface temperature of the FML, which may get to 160°F and higher.
Due to its high coefficient of linear expansion, HDPE tends to expand when
warmed by sunlight, but contracts when cooled. This characteristic can cause
severe stress in the sheeting if it is installed when warm without sufficient
slack. Also, if seamed when warm, both sheetings should be at the same state
of expansion.
7.5.3.2.1.5 Durability. FMLs used to line TSDF containment units
must be durable, i .e. be able to maintain their integrity and performance
characteristics over the operational life of the unit and the post-closure
care period. Ultimately, the service life of a given FML will depend on the
instrinsic durability of the material and on the conditions under which it is
exposed. Differences in composition and construction will cause FMLs to vary
7-60
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in their response to the exposure conditions which, even within a given
facility, can differ greatly. In particular, the FML must be able to resist
the combined effects of chemical, physical, and biological stresses. The
procedures and test results that have been developed to assess the durability
of FMLs are discussed in Chapter 5. Not adequately investigated, however,
are the synergistic effects of combined stresses; these effects need to be
studied through the further investigation of actual field performance.
7.5.3.2.2 Selection of the FML--In selecting a membrane that meets
the performance requirements for an FML, tjie designer must make decisions
concerning:
- Composition.
- Thickness.
- Construction (fabric-reinforced or unreinforced).
- Desired mechanical properties.
The decision about composition will be based primarily on chemical compati-
bility, although in the case of an FML that will be exposed without a soil
cover on the slope of a surface impoundment, compatibility with service
conditions is also an important consideration. The selection of an FML of
a certain thickness, particularly of an unreinforced FML, will probably
result from concerns about mechanical compatibility. Any decision needing
to be made about the construction of an FML depends on the FML composition
selected, i.e. whether that composition is available or a fabric-reinforced
membrane, an unreinforced membrane, or both. In addition, as the mechanical
properties of a fabric-reinforced FML are related to the mechanical prop-
erties of the fabric reinforcement, and since some compositions may be
available with more than one type of fabric reinforcement, the designer must
decide on the desired mechanical properties. Lastly, if more than one FML is
found suitable for lining a particular containment unit, selection of a
particular FML may depend on costs, which are discussed in Chapter 12.
7.5.3.2.3 Effect of FML selection on design—The selection of a
specific FML for use fn lining a treatment, storage, or disposal unit can
affect the overall design and design specification in several ways. An FML
is only a single component of a lining system which, in the containment of
hazardous wastes, can include a soil liner, two FMLs, a leak-detection system
between the two FMLs, a soil cover above the top FML, in the case of a
surface impoundment, and a leachate collection system above the top FML, in
the case of a landfill. These different elements must be compatible so that
each can fulfill its own function. One way in which the selection of a
particular FML can affect overall design is its friction angle. There must
be sufficient friction between the soil liner and the FML combined with
adequate anchorage to prevent slippage of the installed FML down the slope.
The use of an FML with a relatively low friction angle, such as an untextured
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HOPE, can affect the exact design for anchoring the FML. The design of
anchor trenches is discussed later in this chapter.
The coefficient of thermal expansion of the FML can affect its instal-
lation and its performance in service. Ideally, the FML component of a
composite liner should lay flat on top of the soil component. However, the
difference between ambient temperature during installation and the service
temperature may result in excessive waviness or tautness in the FML at the
service temperature. The wrinkles resulting from the waviness may affect
drainage in the leak-detection system or be the site of local stresses re-
sulting in cracking of the FML. Excessive tautness may affect an FML's
ability to resist puncture and localize stress on the seams. Provisions may
need to be included in the design to allow for changes in dimensions result-
ing from thermal expansion or contraction. Residual stresses left in some
FMLs from their manufacture can cause shrinkage when heated by sunlight.
This shrinkage can also affect installation and result in tautness of the
FML.
Depending on the order in which the bid package and the FML specifica-
tions are written and the FML is selected, the selection of either an FML
type or a particular FML can affect the FML specifications because of the
differences between the reference or purchase specifications of the different
FML types. Specifications of FMLs are discussed in Chapter 8.
7.5.3.2.4 FML layout—One part of the fabricator's/installer's job is
to create an FML sheet or panel layout, which is a drawing showing the way
in which the FML will be installed at the unit. In addition to the site
conditions, exact layout will depend on the width of the rolls in which the
FML is manufactured and whether or not the FML is fabricated into panels. An
example of an FML layout with sheets that are 33-ft wide and have a maximum
length of 650 ft is presented in Figure 7-18. An example of an FML panel
layout is presented in Figure 7-19. In an FML layout, horizontal seams on
slopes and seams at the toe of slopes are avoided because such seams are
often likely to be subjected to excessive stresses.
7.5.3.2.5 Attachment to penetrations and appurtenances--In general,
the fewer penetrationsthrough a liningsystem, the better. An excessive
number of protrusions or penetrations makes it difficult to install the
lining system and increases the number of locations where stress concentra-
tions are likely to be generated in an FML or where FML movements are likely
to be restrained. When penetrations are necessary, the seal between the
structure and the FML needs to be liquid-tight. The designer needs to con-
sider the methods of attaching the FML to these structures. An FML can be
attached to a structure with a mechanical-type seal supplemented by chemi-
cally compatible caulking, adhesives, or heat fusion to effect a liquid-tight
seal. Sharp edges on the structure should not contact the FML. Design for
attaching different types of penetrations and appurtenances are discussed in
Section 7.5.7.
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Sump
33 Feet Wide - 650 Feet Long
Figure 7-18. FML sheet layout for a surface impoundment. Total lined area
equals approximately 861,000 ft^. (Source: Schlegel, n.d.)
A A A A A
'11\ /12
A
4-
/
^pzz:
^Toe of
i
it:
Slope
7!--
-i r
i ^ i
r
•-1
/
\ ©
\
A
A
A
/8\ 9
Panel Number /A Seam Number
Figure 7-19. An FML panel layout
7-63
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7.5.3.3 The Interface Between the Soil and FML Components--
The draft Minimum Technology Guidance document on liner systems for
hazardous waste landfills and surface impoundments states that the FML
upper component and the soil lower component should directly contact each
other (EPA, 1985). In this design, the uppermost lift of the compacted soil
component serves as the bedding layer for the overlying FML component. Thus,
the interface between the two components should be designed and constructed
so as to provide a "compression connection" or contact between the two
components so that lateral flow between them is minimized. Contact between
the two components is maintained by the overburden load exerted by the
overlying materials. The design and construction should minimize void space,
channels, and other conditions promoting lateral flow of liquids at this
interface. According to the draft guidance document, this requirement is not
intended to preclude liner installers from purposely leaving designed folds
in the FML to allow for thermal contraction (EPA, 1985). However, it is
intended to preclude the use of a geotextile or other high-transmissivity
bedding material between the upper and lower components.
The two potential drawbacks to the requirement for direct contact
between the FML and soil components relate to the higher safety factor that
results from using a geotextile underneath an FML to prevent puncture of the
FML by sharp objects in the soil or to prevent soil erosion which could
result in eventual rupture of the FML. Section 5.5 reports the results of
various studies that simulated the effects of mechanical stress on the
interaction between an FML and a subgrade. Studies that simulated the
in-service behavior of an FML under hydrostatic pressure to evaluate the
ability of an FML to conform to the irregularties in a subgrade indicated the
effectiveness of using a geotextile to reduce an FML's susceptibility to
puncture (Frobel et al, 1987; Fayoux, 1984). Brown et al (1987) studied the
rate at which liquids flow through flaws in the FML component of composite
FML-soil liners. It was noted that lateral flow between the two components
resulted in higher leakage rates. However, results of tests in a pressurized
system indicated that erosion of the soil liner can occur just below a flaw
in an FML, particularly when the liquid head is large and when the hydraulic
conductivity of the underlying soil liner is greater than 1 x 10~6 cm s~*.
Erosion of the soil liner can result in stretching and eventual rupture of an
overlying FML. Placing a geotextile between the FML and the soil liner could
protect the soil from erosion. However, given the proper preparation of the
soil liner as a bedding layer for the FML and an in-place hydraulic con-
ductivity of 1 x 1Q~7 cm s"l or less, given that liquid head on the bottom
(composite) liner should never be very large, neither of these two concerns
should ever be a problem.
7.5.4 Design of the Secondary Leachate Collection
and Removal System (LCRS)
The function of a secondary LCRS, which is located between the top and
bottom liners of a double-liner system, is to detect and collect any liquid
that has entered the system, i.e. leaked through the top liner, throughout
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the lifetime of the unit including the post-closure care period. Thus,
a secondary LCRS functions as a system for detecting leaks in the top liner.
To fulfill this function, a secondary LCRS must be constructed of materials
that are able to maintain their functional integrity after exposure to the
waste or leachate being contained. In addition, the system must be able to
withstand the stresses and disturbances from overlying wastes, waste cover
materials, and equipment operation, and be able to function without clogging
throughout the lifetime of the unit including the post-closure care period.
A secondary LCRS typically is comprised of a number of subcomponents
including:
- A drainage layer consisting of either granular or synthetic drainage
media.
- A filter system to prevent clogging of the drainage layer and/or the
pipe collection network.
- A strategically-placed network of perforated pipe for transporting
leachate or a waste liquid from the drainage layer to the sump/manhole
system.
- A bedding layer for the pipe network.
- A sump/manhole system which allows collection of the leachate or waste
liquid and access to the pipe network for inspection and possible
repairs through the operational and post-closure care periods.
- Mechanical and electrical equipment for conveying the liquid collected
in the sump/manhole system to a separate storage or treatment area and
for monitoring and controlling the level of leachate above the bottom
liner.
In order to meet the basic performance requirements of a secondary LCRS,
the design engineer needs to consider the following:
- The hydraulic transmissivity of the drainage layer.
- The slope of the drainage layer bottom and the pipe collection net-
work.
- The required size and strength of the collection pipes.
- The spacing and layout of the collection pipes.
- The number and location of the monitoring and leachate/waste liquid
withdrawal points.
- Design capacity of the system.
- The type of drainage system, i.e. granular or synthetic.
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- The compressibility of the drainage system, i.e. the ability of the
system to withstand overburden pressure while remaining functional.
- The mechanical compatibility of the LCRS with the lining system.
- The chemical compatibility of the LCRS with the leachate or waste
liquid to be contained, particularly the compressibility of the
drainage system after exposure to organic constituents of the waste
1iquid or leachate.
- The methods of monitoring and maintaining the performance of the
system. Due to concerns about clogging, periodic inspection of the
pipe system using television equipment may be required. To remove
incrustatons and deposits, the pipes may be flushed out using high-
pressure rinsing devices developed for use in sewer systems. The
requirements for using specific inspection and cleaning systems need
to be considered.
At present, there are no performance standards for secondary LCRSs. In
May 1987, the EPA proposed a series of standards for leak-detection sensi-
tivity and minimum detection time (EPA, 1987b). In these proposed regul-
ations, a secondary LCRS intended for leak detection must be capable of
detecting a rate of top liner leakage that does not exceed 1 gal/acre/day
(gpad) and be capable of detecting top liner leakage of 1.0 gpad or greater
within 24 h of the leakage having entered the LCRS. The one-day criterion
was established based on saturated, steady-state analyses of drainage layer
materials that exhibit minimal wetting up. In order to meet these perform-
ance standards, the EPA proposed the following design requirements:
- A 2% minimum bottom slope of the drainage layer.
- A minimum hydraulic conductivity of 1 cm s~l for a granular drainage
layer.
- A minimum thickness of 12 in. for a granular drainage layer.
- A minimum hydraulic transmissivity of 5 x 10~4 m2 s"1 (2.4 gal/min./
ft) for a synthetic drainage layer.
Requirements were also stated for sump capacity and monitoring.
As part of the design process, the EPA presently requires the compati-
bility testing of each component of an LCRS for a hazardous waste contain-
ment unit with the leachate or waste to which it could be subjected to be
demonstrated (EPA, 1986d). The materials to be used must be exposed to the
leachate or waste liquid under controlled conditions [e.g. those outlined in
Method 9090 (EPA, 1986c; Appendix L)] and tested for appropriate properties.
Polymeric components that have demonstrated compatibility with the waste
liquid to be contained will also need to be fingerprinted so that it can be
demonstrated that the material actually used in the field was equivalent to
that tested for compatibility.
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This section discusses the pipe used in an LCRS, LCRSs with granular
media and synthetic media, pipe network layout, and basic requirements for
the sump/manhole system.
7.5.4.1 Pipe Used in an LCRS--
The primary use of pipe in an LCRS is to collect leachate or waste
liquid from the drainage layer and transport it to the sump/manhole system.
Openings in the pipe should be sufficiently large and spatially arranged to
allow free flow of liquids but not result in significant reduction of pipe
strength. Pipe is also used in constructing monitoring ports and system
cleanouts.
Pipes used to collect and transport leachate or waste liquid in a
secondary LCRS must be able to withstand the overburden pressure resulting
from the overlying layers even after long exposure to the waste or leachate
with which they may be in contact. In constructing waste containment units,
flexible pipes (i.e. those made of polymeric materials) are generally used as
the collection pipes. Stainless steel and carbon steel pipes have been used
as risers and auxiliary cleanouts. The pipes can be installed in an LCRS
either in trenches or in positive projection above the liner. Factors which
must be considered in determining the required structural stability of the
collection pipe include (Bass, 1986, p 41):
- Vertical loading.
- Perforations.
- Deflection.
- Buckling.
- Compressive strength.
- Backfill compaction.
- Loadings during construction.
- Chemical resistance.
Design equations for calculating the vertical load acting on flexible pipe
in both trench and projected conditions are presented in Appendix I. The
weakness of these equations is that it may be difficult to determine the
average unit weight of fill because dense waste may be placed in a single
area rather than spread evenly over the site. The designer should include a
safety factor to balance these uncertainties.
In designing the primary LCRS for a landfill or a waste pile, estimated
leachate flow is used to size and space the pipe system. However, for
secondary LCRSs, flow in the collection system will vary because the rate
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depends on flow through leaks in the top liner. In this case, pipe size and
spacing need to be sufficient to allow rapid transmission of liquids and need
not be designed to remove some predetermined volume rate of flow (EPA, 1985).
In the field, 2-in. diameter pipes have been used, particularly in early
design. At present, 6-in. diameter pipes are generally used and are recom-
mended since larger pipes allow for simpler system maintenance and greater
protection against clogging (E. C. Jordan, 1984). Ramke (1986) recommends
using 200-mm (8-in.) pipe in order to ensure that the pipes can be inspected
by television probes and can be cleaned out with rinsing devices. Equations
for using leachate flow rate to determine pipe size and spacing are presented
in Appendix I.
The collection pipe design must consider the size, spacing, and orient-
ation of holes or slots used to perforate the pipe. Perforations must allow
the leachate or waste to pass but prevent the passage of granular drainage
media into the collection pipe. The size or diameter of these perforations,
therefore, must be matched with the particle size of the drainage media.
Satisfactory performance can be expected (Young et al , 1982) if the drain
gravel gradation and perforation, diameter, or slotting width selected for
the drain pipe satisfies the following U.S. Army Corps of Engineers (1955)
criteria for gradation of filter materials in relation to pipe openings:
For slots:
Dg5 of the drainage media
slot width = \."i.
For ci rcular holes:
of the drainage media
hole diameter
The Bureau of Reclamation (1977, p 235) uses the following criterion for
grain size of filter materials in relation to openings in pipes:
of the drainage media nearest the pipe
maximum opening of drain pipe
where Dg5 is the screen size through which 85% of the drain rock (by weight)
can pass. Cedergren (1967) suggests that the above equations represent a
reasonable range over which satisfactory performance can be expected.
Another criterion for pipe hole size considers the movement of liquid into
the pipe as a function of the ratio between slot width and the wall thickness
of the drain pipe. Knobloch (1969) recommends that the ratio of the slot
width to wall thickness should be greater than or equal to 1.5 in order to
maintain the widest possible hole with low flow resistance. The spacing of
perforations depends on flow as well as pipe strength considerations (Moham-
mad and Skaggs, 1983).
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Further discussion of pipe used in LCRSs can be found in Section
4.2.7, E. C. Jordan (1984), and Bass (1986).
7.5.4.2 Drainage Systems and the Design of a Secondary LCRS--
The drainage layer of an LCRS can be either a granular or a synthetic
system. However, even though the basic function and operation of these two
types of systems are the same, the specific design considerations are dif-
ferent. Therefore, the design of LCRSs with granular and synthetic systems
are discussed separately.
7.5.4.2.1 Granular drainage systems—A wide range of sands and gravels
can be used in LCRSs.Limestone, however, should be avoided because contact
with high pH liquids can result in Ca precipitates that can clog pipe perfo-
rations and the stone itself. Table 7-3 lists granular media, their possible
function in an LCRS, and other factors that need to be taken into account for
media selection. The functions that granular media can serve in an LCRS
include:
- As protectors, to protect an FML against puncture by coarser-grained
media (e.g. drainage gravel).
- As drainage media, to allow drainage of leachate or waste liquid so
that leakage can be detected, collected, and removed.
- As filters, to allow seepage flow while restricting particle move-
ments.
- As bedding, to give structural strength to flexible and semiflexible
pipes.
Geotextiles have also been used in granular drainage systems as protectors
and as filters.
The draft Minimum Technology Guidance document for double liner systems
(EPA, 1985) requires granular drainage layers to have a minimum hydraulic
conductivity of 1 x 10~2 cm s~l. More recently proposed regulations require
a minimum hydraulic conductivity of 1 cm s~* for granular leak-detection
systems (EPA, 1987b). Both require a minimum granular drainage layer thick-
ness of 12 inches. The draft Minimum Technology Guidance also requires a
minimum 12-in. bedding layer of material no coarser than Unified Soil Clas-
sification System (USCS) sand (SP) with 100% of the washed, rounded sand
passing the 0.25-in sieve. The material for the bedding above the bottom FML
was intended to function also as the drainage layer. However, the recently
proposed regulations require a coarser grained material necessitating the use
of either granular or synthetic protectors above and below the drainage layer
(EPA, 1987b).
There has also been concern about the clogging of granular drainage
media caused by both physical-chemical and biological mechanisms (Haxo and
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TABLE 7-3. GRANULAR MEDIA THAT MIGHT BE USED IN LEACHATE COLLECTION AND REMOVAL SYSTEMS
-J
1
— 1
o
Media type
Sand (fine, medium,
coarse)
Well -graded gravel
Coarse, uniform
gravel
Particle size
(diameter
in inches)
1/64 to 1/8
1 (maximum)
1/4 to 3
Potential
function
Protection
Filter
Drainage*5
Bedding
Filter
Drainage'5
Beddi ng
Drainage13
Bedding
Hydraulic
conductivity3, cm s~l
1 x 10-3 to 1 x 10'1
3 x 10-1 to 10
10 to 50
Construction
considerations
High compact ive effort
necessary if used as
bedding.
High compact ive
effect necessary if
used as bedding.
Easy to install and
compact.
Availability
Availability commonly
good for bank run and
clean. Clean sand
necessary for use as
drainage medium.
Availability good,
especially for bank
run.
Regional availability.
Optimal functional
characteristics.
aValues for hydraulic conductivity are for saturated flow conditions.
bpor drainage layers, minimum recommended hydraulic conductivity is 1 x 10~2 cm s~l in the draft Minimum Technology
Guidance document for double liner systems (EPA, 1985) and 1 cm s'1 in proposed regulations for leak-detection systems
(EPA, 1987b).
Source: E. C. Jordan, 1984, p 22.
-------
Haxo, 1988). Ramke (1986) investigated the clogging of the primary LCRSs in
MSW landfills in West Germany. He concluded that granular drainage systems
could be effectively clogged by deposits resulting from biological activity
and physical-chemical reactions. In particular, fine-grained filter mate-
rials and well-graded mixed sand filters appeared to clog relatively quickly.
Ramke (1986) recommends using narrowly graded washed gravel, 16-32 mm (0.63-
1.26 in.) in size.
Construction of a top composite liner on top of the secondary LCRS will
require a barrier above the drainage layer to prevent clogging of the voids
in the drainage layer by infiltration of fines from the soil component and
prevent potential damage to the soil component by piping. This barrier can
be either an FML or a filter layer. Either geotextiles or granular media
can be used as the filter layer. Granular filters consist of a soil layer
or combination of soil layers having a coarser gradation in the direction
of seepage (i.e. leakage) than the soil above the filter. In designing a
granular filter, it is important that the relationship of grain sizes of
the filter medium and the drainage layer be appropriate if the filter is to
prevent rather than contribute to clogging. Criteria for granular filters
are discussed by Bass (1986), Bureau of Reclamation (1974 and 1977), and
Cedergren (1967). Permittivity and filtration criteria for using geotextiles
are discussed in Section 4.2.3.3 and by Bass (1986). A geotextile used as a
filter between an LCRS and an overlying soil liner should not allow clay
particles to extrude through its voids. Thus, the percent open area (POA) of
a geotextile used as a filter between an LCRS and an overlying soil liner
should be equal to zero (Koerner, 1988). POA is defined by the Corps of
Engineers in CW-02215 as the sum of open areas divided by the total area
and expressed as a percentage. The sum of the open areas is determined by
projecting a light through the geotextile onto a screen. A needle-punched,
nonwoven fabric with a POA equal to zero and mass per unit area greater than
or equal to 12.0 oz yd~2 is recommended. To increase the safety factor and
prevent the extrusion of clay particles, a thin FML may be placed on top of
the geotextile.
Figure 7-20 illustrates two possible drainage layer configurations for
granular drainage systems in FML/composite double-liner systems. In Figure
7-20a, sand is used as the primary drainage layer material. The pipe is
buried in coarse uniform gravel to provide additional structural stability.
The bedding media is wrapped in a geotextile to prevent the migration of the
sand particles into the bedding media. In constructing this system, the sand
layer would be placed on top of the liner and then excavated in the required
runs using special equipment (e.g. a backhoe with a rubber blade) to allow
placement of the pipes. This system probably would not meet the proposed
hydraulic conductivity requirement of 1 cm s"1. Figure 7-20b presents a
granular drainage system using coarse, uniform gravel throughout the drainage
layer. A geotextile is placed above and below the drainage layer to protect
the FML liners. It is generally considered the better practice to wrap a
pipe trench with a geotextile (as is shown Figure 7-20a) rather than the
pipe itself. Some engineers have proposed wrapping the pipe with a geo-
textile to prevent drainage media from migrating into the pipe, thus allowing
7-71
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larger pipe perforations. However, this is not the recommended practice
because of concerns about clogging of the geotextile filter, particularly
around the pipe perforations, by fines or other mechanisms. It should also
be noted that some designers may place FML scruff strips underneath all pipe
runs (Salimando, 1988).
gi'.-W.-S..- .-r:-'-. : .:;:•-; Protective L^yerSS'-^l":^:^:^-':^ .-:*;;?;
6 in. Diameter
Perforated Pipe
Top FML
Bedding Media-
Coarse, Uniform Gravel
Geotextile - Separator
FML
(Slope > 2%)
Compacted
Soil Liner
(a)
Protective Layer..
o „'Drainage Media Coarse, Uniform Gravel1 "..
6 in. Diameter
Perforated Pipe
(b)
Top FML
Geotextile - Filter/Protector
Geotextile - Protector
FML
(Slope > 2%).
Compacted
Soil Liner
Figure 7-20. Schematic of granular drainage systems in secondary LCRSs for
double-lined surface impoundments. (Based on E. C. Jordan,
1984, p 29).
Two important problems in designing an LCRS with granular media are
(1) the difficulty of constructing a granular drainage layer on the slopes,
and (2) potential difficulties with constructing components on the slopes
on top of a granular drainage system, particularly those designed with
relatively coarse materials. In order to maintain the integrity of the unit,
a granular drainage system on the slopes needs to be structurally stable so
that sloughing does not occur. Thus, there must be adequate friction (1)
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between the granular media and the bottom FML, (2) between the granular media
and itself, and (3) the granular media and the overlying components (e.g. an
FML). The required slope may be relatively flat, resulting in an inefficient
use of space. Because of the difficulty of installing a granular LCRS on the
slopes, many engineers are designing LCRS systems that use granular media on
the floor and synthetic drainage media on the slopes. In addition, the
drainage system has to stay in place while the layers above are constructed.
In constructing granular drainage systems, it should be noted that single-
size rounded gravel is more difficult to construct on top of than single-size
crushed and washed gravel; however, to obtain the same conductivity, the
required grain size for crushed and washed gravel is significantly higher
than for rounded gravel. When crushed gravel is used in an LCRS, special
measures have to be taken to protect the FML, e.g. a geotextile is placed
above and below the gravel.
7.5.4.2.2 Synthetic drainage systems—The types of synthetic drainage
media that can be used in an LCRS include geotextiles, geonets, and geo-
composites. With the recent commerical development of high drainage capacity
geonets and geocomposites, however, geotextiles are at present generally used
in LCRSs as filters, separators, or protectors. Some engineers are concerned
about the ability of geotextiles to maintain their transmissivity after long-
term exposure because of potential clogging by biological activity or other
means. The use of geonets and geocomposites as drainage media are discussed
in Sections 4.2.5 and 4.2.6, respectively.
Synthetic drainage media have many potential advantages over granular
drainage media:
- Synthetic drainage media may be easier to obtain commercially or be
less expensive than granular media.
- Synthetic drainage media are thin compared with granular drainage
layers and, therefore, allow for larger disposal capacity.
- Synthetic drainage media can be placed on steeper side slopes than
granular materials and, therefore, again allow for larger disposal
capacity.
- Construction can be performed on top of synthetic drainage media,
whereas granular layers (k >1 cm s"l) will not stay in place while
overlying components are constructed.
- Construction quality is easier to evaluate.
The potential disadvantages of synthetic drainage media include:
- The influence of large normal loads on the transmissivity of the
system initially due to the elastic compression of the synthetic
layer and over a period of time due to compressive creep. This is
of particular concern with geonets because of the possibility of
intersecting rib "layover."
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- The effects of exposure to constituents of the waste liquid or leach-
ate on the compressive creep of the synthetic drainage system and
the subsequent effects on transmissivity. Of particular concern are
organic constituents which can soften polymeric compositions and
which can enter the secondary LCRS, both by leakage and by vapor
transmission through the top FML.
- The effect of intrusion by the lining system (above and below) into
the synthetic drainage media. The effects of intrusion into geonets
and geocomposites are discussed in Sections 4.2.5 and 4.2.6. Limited
results of testing the hydraulic transmissivity of three types of
geonets under different boundary conditions are discussed in Section
5.5.3.2. Of particular concern is the effect of constructing the soil
component of a composite liner on top of a synthetic drainage layer.
An example of a synthetic drainage layer system is presented schemati-
cally in Figure 7-21. In this example, a trenched pipe network underlies the
synthetic drainage layer. The gravel used for the pipe bedding is wrapped in
a geotextile to protect the FML components of the bottom composite liner and,
depending on the type of synthetic drainage media, to protect the top FML
liner and the drainage media.
Top FML
Soil Component of
Bottom Composite Liner
Synthetic
Drainage Media
FML Component of
Bottom Composite Liner
Perforated
Collection Pipe
Pipe Bedding
Coarse, Uniform Gravel
Geotextile - Protector
Figure 7-21.
Schematic of an LCRS for a surface impoundment with a synthetic
drainage layer (not to scale). (Based on E. C. Jordan, 1984, p
39).
In the case of a double-lined unit for the containment of hazardous
wastes, one problem with constructing a system containing trenches is the
difficulty of meeting the requirement that the bottom soil liner have a
minimum thickness of 3 ft. The solution to this problem is to overbuild the
clay liner, which, however, can significantly affect costs. In addition,
7-74
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care needs to be taken to prevent stress concentrations when fitting the FML
into the trenches, particularly with stiffen, thicker FMLs. Because of these
concerns, some engineers in designing a secondary LCRS have stacked two or
more layers of geonets instead of installing a trenched pipe network.
However, it should be noted that experience with synthetic drainage media in
land-disposal applications is limited, and their ability to perform on a
long-term basis remains unproven.
It is also possible to design a secondary LCRS which uses granular
drainage media along the bottom of the unit and synthetic drainage media on
the side slopes, as is shown schematically in Figure 7-22.
Bemn
Bottom FML
Synthetic
Drainage Media
Perforated
Collector Pipe
Granular
Drainage Layer
Figure 7-22. Schematic showing the use of synthetic drainage material on
side slopes and a granular drainage system on the bottom of
a surface impoundment. (Based on E. C. Jordan, 1984, p 38.)
7.5.4.3 Bottom Slope—
A relatively high rate of liquid movement is necessary to allow rapid
collection and removal of liquids present in the system and to minimize the
deposition of particles and silt. Because the rate of liquid movement
through an LCRS is proportional to the bottom slope, present EPA guidance
requires an LCRS to have a minimum bottom slope of 2% (EPA, 1985). The
preamble to proposed regulations on leak detection systems (EPA, 1987b)
indicates that this minimum slope requirement applies to all components of an
LCRS, including the bottoms of the drainage media, the collection pipes, the
collection laterals, and all other piping and/or drainage features. Depend-
ing on the design, this requirement may result in areas of the unit with
bottom slopes greater than 2%. It may be necessary to increase the minimum
bottom slope requirements to alleviate concerns that units designed with 2%
bottom slopes could actually end up with slopes less than 2% due to imperfect
construction or post-construction settlement.
7-75
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7.5.4.4 System Layout—
The layout or configuration of the pipe collection system in an LCRS
varies from site to site depending on factors such as site topography,
unit size, climatic conditions, design preference, regulatory requirements,
and the type of waste liquid or leachate that will contact the LCRS. The
spacing of the pipe network is discussed in Appendix I. Layout of the
system should provide alternate paths for the leachate or waste liquid to
flow to the collection point, should allow for access to the drainage layer
and collection sump for inspection and maintenance, and should allow for
minor subsidence of the drainage layer (Bass, 1986). An example of a system
layout for a secondary LCRS for a surface impoundment is presented in Figure
7-23. In this schematic, the collection header penetrates the bottom liner
to connect with a cleanout manhole and a monitoring/collection manhole, and
4' Diameter Cleanout Manhole
K«— 6" or Larger Diameter Access Line
6" or Larger Perforated
Collection Header
\
/
1
1
6' Diameter
^^ Perforated Laterals
IF
3
1 1
o
i
LL
ll
1 ^
1 ^
v Row Direction
r~
i
i
/
\
.«-
o
o
o
f\
o
O^
-------
the auxiliary cleanouts are installed between the top and bottom liners and
penetrate the top liner on the berm. The decision to penetrate the liner and
place a sump outside the containment should be made only after assessing the
relative advantages and disadvantages of such a decision.
7.5.4.5 Sump Requirements—
Leachate or waste liquid is conveyed through the pipe collection network
by gravity to one or more sumps depending on the system layout. The sump
system should be of appropriate size to collect liquids efficiently and to
prevent liquids from backing up into the drainage layer. Proposed EPA
regulations require each unit to have its own sump and require the design of
the sump and removal system to provide a method for measuring and recording
the liquid volume present in the sump and the amount of liquid that has
been removed on a daily basis (EPA, 1987b). In addition, in the case of a
landfill, the LCRS above the top liner and the LCRS between the top and
bottom liners should have separate sump systems. The draft Minimum Tech-
nology Guidance document (EPA, 1985) states that sumps should be capable of
functioning automatically and continuously. The EPA also interprets the
requirement for a maximum 12-in. hydraulic head on a liner to include the
sump.
Sumps for secondary LCRSs can be either outside the unit, as is shown
in Figure 7-23, or inside the unit on top of the bottom liner. Six- and
eight-in. riser pipes have been used for removing liquids from a sump.
Riser pipes can be placed so that they go up the unit's slope in between the
top and bottom liners and penetrate the top liner at the berm. When side
slope risers are used in conjunction with synthetic drainage media on the
slopes, the riser pipes are placed in trenches that run up and down the
slopes. A schematic of a sump system with a side slope riser is shown in
Figures 7-24A, B, and C.
To facilitate inspection and maintenance, manholes have also been used.
Manhole systems inside the unit will need to penetrate the top liner, in
which case the top FML liner will need to be attached to the manhole and
special measures need to be taken to prevent different settlement under the
sump system to prevent tearing of both the top and bottom FMLs. Because of
concerns about differential settlement, down-drag forces, and potential
damage to the lining system, manhole-sumps inside the unit for secondary
LCRSs are generally discouraged.
Manhole-sump systems can also be placed outside the unit. The leachate
or waste liquid entering the secondary LCRS flows to the manhole by gravity
drainage. The placement of a manhole-sump system outside the unit is shown
in Figure 7-23. A manhole-sump placed outside the unit is presented sche-
matically in Figure 7-25. It must be recognized, however, that the outlet
piping must penetrate the secondary composite liner system. In addition, it
should be noted that piping and sump systems that penetrate a secondary liner
for a hazardous waste containment unit will also require a secondary liner.
7-77
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^1
oo
Gravel
Slope 2%-
FML Component
of Top Liner Filter Fabric
\ on Top of Gravel
Filter Fabric
on Top of
Drainage Net
Select Fill
Drainage Net
uia '!.":•>•.• vt*\;
;v;:::::\:..v':.V:y----:-:'::-:;-;.'^'^Select Fill:::::V:'-::^M^Lii
^ x
">^ ' / / / /
Perforated Pipe
Protective Fabric
on Top of FML
^Compacted Clay "//////
FML Component
of Bottom Liner
Filter Fabric
Submersible Pump
Inside Pipe Which
is Perforated at End
NOT TO SCALE
Figure 7-24A. Schematic of a sump system inside the unit for a secondary LCRS with liquid
removal through a side slope riser pipe—Floor of the unit and partway up
the slope. Cross-section A-A is presented in Figure 7-24B. (Based on a
drawing courtesy of Chemical Waste Management, Inc.)-
-------
Filter Fabric
Drainage Net
Protective
Fabric
FML Component
of Bottom Liner
Solid Wall
Steel Pipe
Not to Scale
Figure 7-24B.
Schematic of a sump system inside the unit for a secondary
LCRS with liquid removal through a side slope riser pipe—
Detail of cross section A-A from Figure 7-24A showing trench
for riser pipe on the slopes. Protective fabric extends 5 or
more feet on each side of the trench. (Based on a drawing
courtesy of Chemical Waste Management, Inc.).
The advantage of placing the manhole-sump outside the unit over using
side slope risers is that liquid flow out of the unit depends on gravity
drainage rather than a pump. The advantages of using side slope risers
over placing a manhole-sump outside the unit include:
- Side slope riser pipes penetrate the primary FML at the berm. The
discharge liner from a containment must penetrate both components of
the secondary liner at a low point in the unit.
- If the site is subject to seismic activity, there will be concern
about the ability of the discharge liner to withstand such activity.
- Placing a sump-manhole outside the unit effectively increases the
space required for a unit, resulting in a less efficient use of
overall space.
The hydraulic head in an LCRS sump located inside a unit needs to be
kept at 12 in. or less for three reasons:
- Sumps are often of complex geometry, resulting in a greater potential
for breaches in both FMLs (seam defects, tears, etc.) and compacted
soil components (cracks).
7-79
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5' x 5' Liner
Pipe Boot
Filter Fabric/ Drainage Net/
FML Component of Top Liner
Hand Compacted Clay
Over Pipe at Top of Slope
I
co
o
Steel Pipe
6 In. Concrete Slab
.5' Min. Compacted Clay
3' Compacted Clay
Protective Fabric/ Drainage Net/
FML Component of Bottom Liner
1'Min. Cover to Protect
Pressure Relief Fabric/
Net/Fabric (not shown)
3.5'-
Figure 7-24C. Schematic of a sump system--Berm of the unit. (Based on a drawing courtesy
of Chemical Waste Management, Inc.).
-------
- Since the area around the sump may not have an adequate bottom slope,
liquid entering the sump may pond over the bottom liner.
- Regulatory requirements.
One disadvantage of the requirement is that the submersible pump will always
be working with little or no head.
Manhole Frame and Cover
with Vented Lid
Grade Finished to Slope
Away From Manhole,
Discharge Line From Leak
Granular Backfill
4' I.D. Manhole
Continuous or
Intermittent Monitoring
NOT TO SCALE
NOTE:
Manhole is equipped with discharge pump
Figure 7-25. Schematic of a monitoring and collection manhole located out-
side a unit (not to scale). (Based on E. C. Jordan, 1984, p
34).
7.5.4.6 Auxiliary Cleanouts--
Auxiliary cleanouts allow access to collection laterals from the up-
gradient end. When included in a design, they can extend up the slope and
penetrate the top liner at the berm. Auxiliary cleanouts can be made of the
same materials used to make the collection pipes, and their diameter is
usually equivalent to the collection lateral diameter. An example of an
7-81
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auxiliary cleanout is presented in Figure 7-26. As with side slope riser
pipes, if a synthetic drainage medium is used on the slopes, the auxiliary
cleanout pipes will be installed in trenches that run up and down the slopes.
Top FML.
\ ////
-Elbow
Pipe Boot
(Typical)
Side Slope Media
(Site-Specific)
' ' ' J • Solid Wall Pipe
FML Component / \ 6 in. Diameter Perforated
of Bottom Liner Collection Lateral
NOTE:
Diameter of cleanouts complementary with
collection laterals. Vertical scale is exaggerated.
Figure 7-26. Schematic of an auxiliary cleanout (not to scale). (Based on
E. C. Jordan, 1984, p 34).
7.5.5 Design of the Top Liner
The top liner of a double liner system for a hazardous waste contain-
ment unit can be either an FML or a composite liner made up of an upper FML
component and a lower compacted low-permeability soil component similar in
design to the bottom composite liner. This section describes these two basic
design options.
7.5.5.1 An FML-only Top Liner—
The basic requirements for an FML top liner are the same as those for
the FML-component of a bottom composite liner. These requirements include:
- Low permeability to constituents of the waste liquid or leachate to be
contained.
7-82
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- Chemical compatibility with all constituents of the waste liquid or
leachate to be contained.
- Mechanical compatibility with the service conditions.
- Durability.
- Capability of being installed.
These requirements are discussed in Section 7.5.3.2. It should be noted that
the service conditions of a top FML liner can be significantly different from
the service conditions for a bottom liner, depending on the type of contain-
ment unit. This section discusses design problems specific to top liners.
These include special considerations regarding mechanical interaction with
the drainage layer of the secondary LCRS and considerations about thickness,
particularly of unreinforced FMLs.
7.5.5.1.1 Interaction between an FML and a drainage layer—An FML can
interact with a drainage layer either above or below the liner in two ways,
depending on whether the drainage system is granular or synthetic. A rel-
atively coarse granular medium can puncture an FML because of the combined
overburden and hydraulic forces acting on the FML. In addition, potential
interaction with constituents of the leachate or waste liquid may decrease
puncture resistance of the FMLs. To alleviate concern about puncture, a
relatively thick FML could be specified in conjunction with either a geo-
textile or a granular bedding layer placed on top of the drainage gravel.
Because of its flexibility, an FML can interact with a synthetic drain-
age medium by intruding, when under load, into the voids necessary for
drainage. This intrusion can significantly affect the transmissivity of the
drainage system. The intrusion of FMLs into geonets and geocomposites is
discussed in Sections 4.2.4 and 4.2.5. The mechanical compatibility of the
FML with a synthetic drainage system should be investigated in a transmis-
sivity test in such a way that the drainage system is exposed to mechanical
stresses that simulate actual service conditions. The profile of layers
tested in the transmissivity apparatus should simulate the profile of the
lining system to be used in the field (see Section 5.5.3). Testing may
indicate the need for a different combination of FML and synthetic drainage
media.
7.5.5.1.2 FML thickness considerations—The physical properties of
unreinforced FMLs are proportional to their thickness, and, therefore, the
historical trend has been to use thicker membranes. Whereas in the 1960's,
FMLs were generally 10 to 20 mils in thickness, at present they range from 30
to 120 mils. The draft Minimum Technology Guidance document on double liner
systems for hazardous waste landfills and surface impoundments requires the
FML top liner to be at least 30 mils in thickness (EPA, 1985). However, if
the FML is to be exposed to the weather for an extended period before it is
covered by a protective soil layer or waste, or if the FML is to be used
without a protective cover, a minimum thickness of 45 mils is proposed (EPA,
1985).
7-83
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If an unreinforced FML is being used, a thicker liner may be required to
prevent failure while the unit is operating, including the post-closure care
period. The adequacy of the selected thickness should be demonstrated by an
evaluation that considers the type of FML and site-specific factors such as
expected operating period of the landfill or surface impoundment unit,
pressure gradients, physical contact with the waste and leachate, climatic
conditions (environmental factors), the stress of installation, and the
stress of daily operation (e.g. placing wastes in the landfill or sludge
removal in surface impoundments). Operational stresses tend to be higher for
surface impoundment units than for landfill units. As is discussed in
Section 5.2.4, service conditions in surface impoundments tend to be more
severe than those in landfills because of factors such as:
- Cleaning or maintenance activities.
- Thermal stress.
- Hydrostatic pressure (head and wave action).
- Abrasion.
- Weather exposure (ultraviolet light, oxygen, ozone, heat, and wind).
- Operating conditions (inlet and outlet flow, active life, exposure to
animals, treatment processes).
Because of these factors, uncovered surface impoundments lined with unrein-
forced FMLs are frequently lined with FMLs 60 to 100 mils in thickness. A
protective layer covering the top liner in surface impoundments can reduce
the operational stresses on the FML. Overburden stresses on landfill and
waste pile liners will depend on the height and density of the waste placed
in the unit. Units designed to contain large volumes of dense waste may also
require FMLs thicker than the minimum specified thickness.
7.5.5.2 Composite Top Liner--
The results of a study performed by Brown et al (1987) indicate that
flow rates through small holes in an FML are significantly affected by the
permeability of the layer underlying the FML. These results showed that
when an FML is in contact with an underlying low-permeability soil (with a
hydraulic conductivity in the range of 1 x 10~6 cm s"1), the flow rates
through small holes in the FML were approximately five orders of magnitude
lower than they were when the same size holes were underlain by a gravel
(with a hydraulic conductivity in the range of 1 x 10"1 cm s'1). Because
of these results, Buranek and Pacey (1987) and other designers have recently
proposed the use of a composite soil and FML liner as the top liner of a
double liner system, resulting in a double composite liner system [see also
Buranek (1987)]. An example of a double composite liner system is presented
in Figure 7-27.
7-84
-------
I
oo
Protective soil cover
Geotextile ) _ . . __„
> Primary LCRS
Geotextile^ Secondary
Geonet
LCRS
Geonet
FML
i— Compacted clay ' Liner
\ Top Composite
- Compacted clay; i_ j n e r
\ Bottom
> Composite
VAX//NX
Subgrade foundation
NOTES:
1. Primary LCRS components are not applicable for surface impoundments.
2. Primary and secondary LCRS may be granular materials.
3. Protective soil cover may be optional for surface impoundments.
I
Figure 7-27. Schematic of a double composite liner system. (Source: Buranek and Pacey,
1987, p 379).
-------
The primary potential advantage of a composite top liner over an FML-
only top liner is that a composite liner will reduce the amount of leachate
that enters the secondary LCRS between the top and bottom liners. The dis-
advantages of a composite top liner include:
- An increase in the amount of time necessary to detect a leak in the
top FML since the leachate or waste liquid must pass through the clay
component of the liner before entering the leak-detection system.
- An increase in cost of the top liner.
- An increase in the complexity of constructing a containment unit.
- A decrease in the capacity of the unit.
- Potential damage to the FML component of the bottom composite liner
due to the construction above the liner.
- Lack of knowledge about the mechanical interaction between the soil
component of a top composite liner and a secondary LCRS designed with
synthetic drainage media.
The results of a study evaluating the mechanical interaction between a
synthetic drainage media, a geotextile, and an overlying soil were presented
in Section 5.5.3.2. These results show that a geonet tested in a cross
section simulating a liner system with a top composite liner allowed a
flow rate that was 20 to 40% that of a geonet tested in a cross section
simulating a liner system with an FML-only top liner, indicating intrusion of
the geotextile into the drainage medium. Stresses during the compaction
could result in (1) further intrusion into the drainage layer preventing flow
in the system or (2) excessive loadings on the geotextile-filter component of
a geocomposite, causing the fabric to tear and allow soil to enter the
drainage system. In addition, the compactive effort used to construct a soil
liner could cause the collapse of the drainage media. It should be noted
that long-term creep of the geotextile or geonet could also result in all of
these same effects; the effects of creep need to be investigated.
Another important consideration is the possibility of the clay extruding
through the voids of the geotextile and clogging the drainage systems. As is
discussed in Section 5.5.3.2, results of tests with a needle-punched, non-
woven polyester, continuous filament fabric of 16 oz yd~2 mass per unit
area indicated that the clay did not extrude through the geotextile. After
analyzing the data, Koerner (1988) recommended two minimum requirements for a
geotextile used as a filter above a geonet serving as the drainage media for
a secondary LCRS:
- The geotextile should have a percent open area (as defined by the
Corps of Engineers in CW-02215) equal to zero.
- The geotextile should be a needle-punched nonwoven fabric with a mass
per unit area greater than or equal to 10.0 oz yd~2.
7-86
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At the present, there are no guidelines concerning the construction or
performance of the soil component of a top composite liner. However, the
first layers of soil placed on top of the LCRS will probably not be compacted
as part of the soil component. Depending on the type of drainage system used
in the secondary LCRS, the soil may not be compacted with the same effort as
the soil component of the bottom composite liner; thus, some designers may
require it to be compacted for a lower hydraulic conductivity than that re-
quired of the lower soil liner. It should be noted that some engineers have
designed and constructed 18-in. thick liners compacted in 6-in. lifts and re-
quired the liner to have a minimum hydraulic conductivity of 1 x 10~7 cm s~l.
Some experimentation has been performed using prefabricated rolls of dry
bentonite pellets sandwiched between geotextile layers as the soil component
of a top composite liner. The prefabricated rolls are unrolled on top of the
secondary LCRS, and the top FML is installed directly on top of them. When
moisture meets the dry clay, it swells and forms an _TJT_ situ barrier. No
quantitative data are currently available.
7.5.6 Design of a Primary Leachate Collection
and Removal System (LCRST
The primary LCRS system is installed above the top liner in waste piles
and landfill units. The function of the primary LCRS is to minimize the head
of leachate on the top liner during operation of the containment unit and to
remove liquids through the end of the post-closure care period. Current EPA
regulations require that the primary LCRS be designed to ensure that the
leachate head above the top liner does not exceed 1 ft [40 CFR 264.251 and
264.301 (1986 ed.)]. Other basic requirements for a primary LCRS are the
same as those for a secondary LCRS (see Section 7.5.4). Thus, a primary LCRS
must be constructed of materials that are able to maintain their functional
integrity after exposure to the leachate, be able to withstand the stresses
and disturbances from overlying materials and equipment, and be able to
function without clogging throughout the lifetime of the unit including the
post-closure care period. However, it should be noted that some designers
are choosing to use different types of drainage media for the primary and
secondary LCRSs.
The design considerations for a primary LCRS are essentially the same as
those for a secondary LCRS. The major difference is that primary LCRSs are
designed to handle an estimated amount of leachate. One tool for estimat-
ing the amount of leachate that can be generated by a landfill is the HELP
computer model (Schroeder et al, 1984a and 19845), which is discussed in
Section 7.3.1.1.7. The estimate for the amount of leachate generated (i.e.
the amount of leachate that will enter the LCRS) is used in design equations
to size and space the pipe system. Equations for using leachate infiltration
rate to determine pipe size and spacing are presented in Appendix I.
The draft Minimum Technology Guidance document on dou51e-liner systems
states that a primary LCRS should have (EPA, 1985):
- At least a 30 cm (12-in.) thick granular drainage layer that is
chemically resistant to the waste and leachate, with a hydraulic
7-87
-------
conductivity not less than 1 x 10~2 cm s"1 and with a minimum bottom
slope of 2%. Leachate collection systems incorporating synthetic
drainage layers may be used if they are shown to be equivalent to or
more effective than the granular design, including chemical compati-
bility, flow under load, and protection of the FML (e.g. from punc-
ture). Granular drainage material should be washed to remove excess
fines before installation.
- A graded granular or synthetic fabric filter above the drainage layer
to prevent clogging.
- A drainage system of appropriate pipe size and spacing on the bottom
of the unit to efficiently collect leachate. These pipe materials
should be chemically resistant to the waste and leachate. The piping
system should be strong enough to withstand the weight of the waste
materials and vehicular traffic placed on or operated on top of it.
- A drainage and collection system that covers the bottom and sidewalls
of the unit.
- A sump for each unit or cell capable of automatic and continuous
functioning and which should be able to remove accumulated leachate at
the earliest practicable time to minimize the leachate head on the top
liner which should not exceed 12 inches. The sump should contain a
conveyance system for removing leachate from the unit such as either a
sump pump and conveyance pipe or gravity drains. Examples of manhole
sumps for a primary LCRS are shown in Figures 7-28 and 7-29. A plan
view for the sump design presented in Figure 7-29 is presented in
Figure 7-30. Side slope risers can also be used for removal of
leachate from a primary LCRS sump. It should be noted that many
engineers believe the maximum 12-in. head requirement, if the sump is
placed inside the unit, to be too stringent because of the consequent
requirements for the sump pump.
- The collection lines should be capable of being cleaned out periodi-
cal ly.
If the manhole sump is placed within the containment unit, as is shown in
both Figures 7-28 and 7-29, special care will need to be taken in designing
and constructing the system to prevent differential settlement of the sup-
porting soils and to prevent down-drag forces from affecting the integrity of
the lining system. Different settlement of the supporting soils could result
in tipping of the standpipe and eventual puncture of the FML. The down-drag
forces arise from the differential settlement that occurs between the con-
solidating waste fill and the rigidly supported manhole pipe. These forces
are transmitted to the base of the standpipe and can generate high stress
concentrations on the underlying liner system components. Special measures
may be taken to prevent the consolidating waste from pulling down on the
manhole standpipe by lowering the friction between the pipe and the waste.
Richardson and Koerner (1987) present design equations for evaluating down-
-------
drag forces to compare coatings for reduction of these forces and to evaluate
whether down-drag induced settlement of the standpipe will cause failure of
an underlying LCRS.
Fencing
Pipe for
Primary LCRS
Sand
Top FML
Reinforced
Concrete Base
FML Wrapped Around Steel Plate
to Protect Top FML
Figure 7-28.
Schematic of a low-volume sump for a primary LCRS. Sump pump
is not shown. The zone of gravel around the standpipe is
retained during operations by fencing. The steel plate below
the concrete pad is included to allow stress transitions.
(Based on Richardson and Koerner, 1987, p IV-6).
In general, penetration of the lining system is strongly discouraged.
However, under special conditions, a designer may decide to place the sump/
manhole system for a primary LCRS outside the containment unit, even though
the discharge pipe will penetrate the lining system. For example, a designer
may consider placing a manhole sump outside a containment unit if the unit is
a single-lined MSW landfill that is being constructed above-grade and if the
MSW height is projected at 100 ft or higher. If the sump/manhole is placed
outside the containment unit, the penetrating pipe will require special
foundations and seals. An example of a sump placed outside a unit is pre-
sented in Figure 7-25.
7-89
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I
IJ3
O
HOPE
Standpipe
6-in. Thick Bentonrte Paste
Full Length of Pipe to
Top of Gravel
-.^k^k^AA-.v. --- ^ <•.•••.'" .' *'• •: - Primar LCRS Gravel . '
.' -FMLCapSheet .%'«. % .». ... - - „
•'.'• ' ' '' ' V Stofi>2%"- ™Lv' -••
- Filtor r.loth • \ S>°Pe - ^'o . . ^ . V - • •_
----:V. • . •• FML Cap Sheet -. •
"~~~ " "X... ' • ••" •"
".*••*• • 1 -in Perforations
Filter Cloth
'•'- Wrapped
'o * Pipe o
• .- FML Liner Welded •••„
to HOPE Pad..':
• (option).**
• • .\ p » '
•" •. \kir-
-«« • >' —«- i
•I-I- Compacted Clay I-C-
FML
Geotextile
Concrete Pad
Sand
HOPE Pad Anchored
to Concrete Pad
4-in. HOPE Pipe (in pad)
Sloped to Drain to Center
Secondary LCRS
(Granular Drainage Media)
NOT TO SCALE
(Slopes exaggerated)
Figure 7-29. Schematic of a high-volume sump for a primary LCRS. The pump is not shown.
Plan view of the HOPE pad is presented in Figure 7-30. (Based on a drawing
courtesy of Chemical Waste Management, Inc.).
-------
Thick HOPE Impact Pad
to Protect FML Liner
HOPE Welding Ledge
for FML Cap Sheet
(option)
Concrete Underneath
FML Cap Sheet
HOPE Standpipe
Edge of Concrete Pad
Underneath FML Cap Sheet
is Rounded
4 - inch HOPE Pipe Stoped to Drain
to Center. Screen Provided at Pipe
Ends to Stop Gravel.
Figure 7-30. Plan view of a high-volume sump for a primary LCRS. (Based on
a drawing courtesy of Chemical Waste Management, Inc.).
7.5.7 Design of Ancillary Components
This section discusses the design of various ancillary components of a
double-liner system and a waste containment unit. These components include:
- Anchor trenches.
- Penetrations.
- Liner protection from pipe outfall.
- Gas vents.
- Soil covers.
- Coupon testing for monitoring FML performance.
- Groundwater monitoring systems.
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7.5.7.1 Anchor Trenches--
Proper anchoring of the FML at the top of the slopes around the unit
perimeter is essential to prevent the FML from sliding down into the unit.
An anchor should provide sufficient restraint to prevent this movement but
should not be so rigid or strong that the FML tears before the anchor yields.
Generally, the FML is anchored at the top of the berm using one of the
following methods:
- A friction method.
- A trench and backfill method.
- Anchoring to a concrete structure.
These methods are presented schematically in Figure 7-31. The trench and
backfill method is the one that is recommended most often by FML manufact-
urers, probably due to its simplicity and economy. Richardson and Koerner
(1987) have developed design equations for determining the anchor capacity
for an FML placed in various anchorage configurations.
7.5.7.2 Penetrations--
Depending on the design and purpose of the unit, one or more types of
structures may penetrate the lining system. These penetrations could include
inlet, outlet, overflow, or mud-drain pipes; gas vents; level-indicating
devices; emergency spill systems; pipe supports; or aeration systems.
Penetrations may occur in the bottom, through one of the sidewalls, or on the
berm, depending on the purpose for the penetration. Because tailoring and
sealing an FML around structures can be difficult and offers a possibility
for failure of the FML, many engineers, designers, FML manufacturers and
facility owners recommend that over-the-1iner pipe placement be used whenever
possible. This design facilitates future repairs or maintenance to the
piping system. However, some penetrations of the lining system may still be
necessary; for example, a side slope riser pipe for a secondary LCRS will
need to penetrate the liner, if only through the berm.
Most manufacturers recommend specific materials and procedures to be
used to establish an effective seal around penetrations. Proper design of
the penetrations and use of a bonding system that is practicable with the
geometry of the penetration are important factors in long-term liner per-
formance. When piping systems penetrate a lining system, concrete structures
or collars around the pipe are used to support the area around the penetra-
tion. Since FMLs are not easily bonded to concrete with an adhesive, they
are usually mechanically anchored to the structure. The edges of the con-
crete structure or collar in contact with the FML are rounded to prevent
damage to the liner in case of different settlement between the structure and
the soil subgrade.
Most FML manufacturers offer standardized engineering designs for
(a) seals made in the plane of the liner, and (b) boots to be used around
7-92
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Slo*pe
i
,«***
HORIZONTAL ANCHOR
1% Slope
y TVD.
*
1' .
T-2' Typ.
TRENCH ANCHOR
.-••-
»•••«%
SHALLOW 'V ANCHOR
Top of Slope —*j
Bolted Anchor System
—*, 1X Slope ——
Polymer Batten Strip
CAST CONCRETE ANCHOR
Figure 7-31. Schematic presenting different methods of anchoring FMLs. Note that in
the trench anchoring system, the edge of the berm where the Ff1L enters the
trench is rounded. (Source: Richardson and Koerner, 1987, p 111-22).
-------
penetrations. If inlet or outlet pipes are introduced into the unit through
a concrete structure, the seal can be made in the plane of the lining system.
An example of this type of seal is presented in Figure 7-32. The specific
FML-to-concrete bonding system that is used will depend on the type of FML.
Anchor bolts embedded in the concrete and stainless steel or thick polymeric
batten strips can be used to secure the FML to the concrete. An appropriate
mastic should be used under the edges of the FML to effect a complete seal.
Geotextile
FML
Range Cover
Geotextile
Steel Pipe
Figure 7-32.
Example of a flange seal
Poly-America, Inc.).
around a penetration. (Courtesy of
Typically, specialized features such as pipe boots or shrouds are
fabricated at the manufacturing facility to design specifications, although
they can sometimes be prepared in the field by experienced personnel. Boots
(or shrouds) are designed to fit over an appurtenance (e.g. pipe) and then be
bonded directly to the installed FML so as to create a continuous membrane
around the base of appurtenance. Boots are generally fabricated out of
materials of the same composition as the FML that is being installed so that
they can be bonded to the FML using thermal or solvent-based techniques.
Where fabric-reinforced FMLs are being installed, manufacturers sometimes
recommend that boots be constructed of unreinforced material so that the
slightly undersized boot can be stretched over the appurtenance to assure
7-94
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after the FML roll or
pipe. The appropriate
good physical contact. This also allows some expandability in case the
adjacent FML stretches due to settling. A pipe boot is slipped over the pipe
panel has been cut and fitted around the base of the
adhesive, mastic, or seal (e.g. a closed cell sponge)
is placed between the pipe and boot as required, and a stainless steel band
is placed around the boot where the adhesive, mastic, or seal has been
applied between the pipe and boot. The base of the boot is seamed to the
main part of the FML liner using the same bonding system used to make the
field seams. Boots need to be checked prior to installation to ensure that
the angle of intersection with the base is consistent with the angle created
between the pipe and subgrade. An example of a seal created through the use
of a pipe boot is presented in Figure 7-33.
FML
Stainless Steel Flat Bar
(2 in. wide. 0.25 in. thick)
over closed cell Neoprene
Sponge bolted 6 in. on center
. with 0.375 - in. bolts
Stainless Steel Clamp
Closed Cell
Neoprene Sponge
Extrusion Weld
Figure 7-33.
Example of a seal around a penetration using the boot-type
method. (Courtesy of Poly-America, Inc.).
7.5.7.3 Gas Vents-
Certain conditions require the venting of gas that may accumulate be-
neath an FML. If organic matter exists in the soils under the lining system,
natural gas is present in the region, gas generation is inevitable. If
flat bottom, gas will tend to accumulate under the liner. In
surface impoundment, if the pressure is permitted to increase,
or if
a unit has a
the case of a
7-95
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the FML can be lifted creating a cavity for additional gas accumulation. The
higher the FML bubble is allowed to rise, the more the FML stretches and the
less hydrostatic pressure is available to restrain the FML. As a result, the
FML can float to the surface. In landfills, due to the weight of the waste
and overburden, the FML cannot float upwards.
Venting must also be considered when a fluctuating water table is
present immediately below the unit bottom. When the water table falls, void
spaces in the soil under the liner are created. Air is then drawn into these
voids from the surrounding soil. Conversely, when the water table rises,
air which was pulled into the voids is displaced upward. The amount of
fluctuation, proximity of the water table to the unit bottom, and the area of
the base of the unit will dictate the reaction of the lining system to this
air pumping mechanism. The need to vent this accumulating gas is best
accomplished by constructing a venting underdrain system (see Section 7.5.1)
underneath the entire lining system. One method is to install above the
foundation a layer of clean sand of which less than 5% by weight will pass
the 200 sieve (0.075 mm). Synthetic systems using geonets and geotextiles
can also be used. In order for these media to be effective, the bottom of
the unit should slope up from its lowest point to the toe of the embankment a
minimum of 2%, and the lining system must have sufficient stiffness. The
venting medium should cover the entire bottom and the side slopes. In the
case of surface impoundments, venting to the atmosphere is accomplished
through gas vents located on the inside slope of the berm, approximately one
foot down from the crown of the embankment. Simplified representations of
two designs of gas vents for single-lined surface impoundments are presented
in Figure 7-34 and 35. A schematic showing a venting system for a double-
lined surface impoundment is presented in Figure 7-36.
7.5.7.4 Liner Protection from Pipe Outfall —
Special considerations must be given if hydraulic impact head is going
to be dissipated onto the top liner. This could occur, for example, at an
inlet structure where liquids flow into the unit. In addition, the main
liner may need to be protected from any abrasive material that might be
present in the liquid discharged into the unit. A splash pad can be con-
structed under the inlet structure by placing one or more additional layers
of the FML used to line the unit at the point of impact to help absorb energy
resulting from the inflow of water (Figure 7-37). A concrete pad or a filter
fabric geotextile placed under the FML can also be used to ensure further
mechanical stability. Alternative solutions include sluice-type troughs and
splash tubes. Troughs can be constructed out of the FML used to line the
unit and placed on top of the main FML liner (Figure 7-38). Splash tubes are
flexible polymeric tubes which are attached to the inlet pipe so that liquids
flow out the inlet pipe through the tube directly onto the FML liner.
7.5.7.5 Aeration System--
If an aeration system is included in the design of a surface impound-
ment, appropriate precautions need to be taken to ensure that the FML sur-
rounding the structure remains in position. With a floating aerator, this is
7-96
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FML
Synthetic
Drainage Media
Vent Placed Higher than
Maximum Liquid Level
at Overflow Conditions
Gas Flow
2" Dia. hole thru panel
Cover - to be sealed to PVC pipe
& elbow and then seal to
reinforcing panel
2" Dia. PVC pipe
Reinforcing panel
Liner
Figure 7-34. Two views of a gas vent design for a single-lined surface
impoundment. The reinforcing panel is placed over a hole cut
in the liner to allow gases to escape from underneath the
liner. (Design based on a drawing courtesy of Sta-Flex
Corporation).
7-97
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Air/Gas Vent Assembly
Openings in Vent are Higher than
Top of Berm or Overflow Liquid Level
FML
Synthetic
Drainage Media
f
ft
Y1
I
>
Skirt of Vent
Bonded to Liner
Gas Flow
Figure 7-35.
A gas vent design for a single-lined surface impoundment,
(Based on Koerner and Richardson, 1987, p 111-29).
Anchor Trench
'Gas Vent
Plastic Drainage Nets
Covered with Single Layer
of Geotextile
U-.:-'.Gravel Bedding':
Top FML
Leak Detection, Collection,'
and Removal System
FML Component
of Bottom Liner
Geotextile
Figure 7-36.
Schematic of a double-lined
venting system underneath the
for a more detailed treatment
final cover for a landfill).
surface impoundment with a gas-
lining system. (See Figure 7-41
of a gas-venting pipe system in a
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usually accomplished by using a mooring pad placed on top of the FML liner.
The mooring pad also prevents mechanical damage to the FML immediately
adjacent to the aerator. It is recommended that an additional layer of FML
be placed between the mooring pad and the main part of the liner. When a
fixed aerator is used, the FML liner may cover the foundation pad, and an
additional pad can be placed on top of the liner. An additional layer of FML
can be sandwiched between the top pad and the FML liner. Permanent anchors
can be placed 10 ft apart in a circle approximately 20 ft from the base of
the aerator to prevent the FML liner from being lifted from the subgrade.
Figure 7-39 shows some typical design details for aeration structures.
FML Boot with
Stainless Steel Clamp
Inlet Pipe
FML
Batten Anchor
System
Bolts on Approx
s 12" Centers
_ft^ & —&
-v^^
ifi t
XI
Concrete Pad
See Detail A
Fastener: Red-Head
' or Ram-set
FML
Stainless Steel
Batten
1-in. y. 1/8-in.
— \ Butyl Tape
)-.-;-.^^--~.~:±~-
I DETAIL A |
•
Concrete
~\A
:
^i|.. /
' v*'- • 'i •• \
<\. . • 'f'.-- •• -^
•V •• I
Pad— -^
Adhesive
/ FML
/ /
/ /
L
'••\- \
\ ••'•
\ ^
Adhesive
Figure 7-37. Splash pad construction using a concrete subbase. (Courtesy of
Burke Rubber Company)
7.5.7.6 Protective Soil Covers —
An earth cover is commonly placed on an FML as a protective layer
against mechanical, weather, and other environmental damage. FMLs have
relatively little structural strength, and some are quite sensitive to such
environmental conditions as:
- Ultraviolet light which can degrade FMLs not properly compounded or
protected.
7-99
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6'DIA
LINER
Figure 7-38.
Sluice-type trough constructed of FML. The easiest method of
placing inlet and outlet pipes into an FML-lined surface im-
poundment is over the top of the berms, using a protective
FML layer to contain the discharge, thus protecting the top FML
liner. The fewer protrusions that are designed into a lining
system, the easier it is to install and maintain both the
lining system and the piping. (Courtesey of B. F. Goodrich).
Infrared radiation which, by heating the FML, can cause evaporation of
the volatile constituents and oxidative degradation of the polymer.
Mechanical damage from solid waste primarily during placement of the
waste in the unit.
Wind, which can cause increased evaporation of constituents in some
FML compounds, and possibly cause mechanical damage to the liner
itself.
Wave action in a surface impoundment.
Oxygen and ozone.
Freeze and thaw.
Hail and rain.
Animals - hoofed, gnawing, etc.
Vandalism.
7-100
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Protective pad for
fixed aerator
Additional layer
of membrane p-
\ rL-
Vp
^X^&L
y
Foundation -'
i / n
•S^^
Membrane liner
3>^
•
-------
Other weather conditions often dictate the necessity for special de-
sign or performance features. Hail can cause failure of some exposed liner
materials, particularly on flat berms where a thermoplastic FML has been
installed. Such damage can be easily prevented by the use of a soil cover.
Liners exposed to high wind can be stretched and damaged by air lift, if
compensations are not made in the design.
In specifying a soil cover, the engineer needs to state that the cover
soil should never be pushed down the slope during placement since the gravi-
tational stresses may pull the FML out of the anchor trench or cause the FML
to tear.
Richardson and Koerner (1987) have developed a design equation for
analyzing the stability of a soil cover placed on top of the slope of an
FML-lined unit.
7.5.7.7 Use of Coupons to Monitor the Liner and Other Materials
of Construction During Service—
In light of the limited experience with FMLs in lining waste containment
units and the lack of information on actual liner performance, it is desir-
able to monitor the condition of an in-service FML during operation of the
unit. One method of monitoring the condition of a liner is to place samples
or "coupons" of the same lot of an FML that is used to line the containment
unit in the unit before the addition of the waste. These coupons should be
withdrawn on a planned schedule and tested. Means to accomplish such a
program must be incorporated in the original design of the unit and plans
made for the withdrawal and testing of the coupons during service. Coupon
placement should allow for essentially the same exposure and environment to
the waste as the installed FML, safe and easy access and retrievability,
economical placement, precise location, and precise identification. Use of
coupons is discussed in more detail in Section 11.7.
7.5.7.8 Groundwater Monitoring Wells—
Monitoring wells are a tool for monitoring the hydrology surrounding a
waste containment unit. A monitoring well is built specifically to give
access to the groundwater so a "representative" sample of water can be
withdrawn and analyzed. There are several components to be considered in
designing a monitoring well. These include:
- Location and number of wells. The wells need to be located spatially
and vertically to ensure that the groundwater flow regime of concern
is being monitored.
- Diameter of the well.
- Casing and screen material. The type of material used in constructing
a monitoring well can have a distinct effect on the quality of the
water sample to be collected. Thus, the materials of choice should
neither absorb nor leach chemical constituents which would bias the
monitoring tests.
7-102
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- The length of screen and the depth of placement. The screen length
determines the height of the zone being monitored.
- Sealing material and procedures. Vertical movement of groundwater can
greatly influence sample quality; therefore, monitoring wells are
usually sealed to isolate the screened interval selected for sampling
and to inhibit downward leakage of surface water.
- Methods of preventing the well screen from clogging.
- Security.
These design considerations are discussed in more detail by Barcelona et al
(1987). EPA (1986e) presents current EPA guidance on groundwater monitoring.
Monitoring wells are also discussed in Section 11.5.1.
7.5.8 DESIGN OF A LANDFILL COVER SYSTEM
At the end of the active life of a landfill, a final cover is con-
structed over the fill to minimize leachate formation within the landfill by
preventing surface water from infiltrating the fill throughout and beyond the
post-closure care period. The final cover system also controls the venting
of gases that may be generated within the fill and isolates the wastes from
the surface environment. Cover systems can also be installed on surface
impoundments at the time of final closure if it has been decided that the
impoundment can be closed as a landfill [40 CFR 264.228 (1986 ed.)]. If this
is the case, free liquids will need to be eliminated either by removing the
liquid wastes and/or solidifying the remaining wastes and waste residues, and
the remaining waste will need to be stabilized to a bearing capacity suf-
ficient to support a final cover. The final cover system should be designed
and constructed so that it can function with minimum maintenance, promote
drainage, minimize erosion, accommodate settlement and subsidence, and have a
transmission rate less than or equal to that of the bottom liner system [40
CFR 264.310 (1986 ed.)].
In designing a cover system, it is important to allow for settlement
within the close waste containment unit because of potential damage to
the cover. Even though settlement of the impounded waste may be uniformly
distributed throughout the unit and occur primarily before the unit is
closed, localized subsidence (i.e. unevenly distributed settlement) can
disrupt the integrity of the final cover. In addition, such subsidence due
to the collapse of drums (which will occur mainly in older units) or the
leaching of soluble waste constituents may not occur until several years
after final closure or may occur gradually over decades. In designing the
cover, the following need to be considered:
- Consolidation of soils and foundation materials underlying the site.
7-103
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- Consolidation of the lining and the leachate collection and removal
systems.
- Consolidation of all waste layers and daily and intermediate soil
covers.
- Consolidation of all final cover components.
Gilbert and Murphy (1987) describe techniques for predicting, reducing, and
preventing landfill settlement and related cover damage caused by subsidence.
The final cover system is similar to the lining system in that both
consist of a number of different components, each of which must function
properly and maintain its integrity if the system as a whole is to function
adequately. Final cover systems are multilayer structures constructed in
layers on top of a mass of waste that may settle unevenly. The barrier layer
is the most important layer because it prevents water from infiltrating the
fill. Depending on the type of waste contained in the unit, the barrier
layer can be comprised of either a clay liner or a composite clay-FML liner.
Other layers are included to protect or enhance the performance of the
barrier layer. An example of a final cover system is presented in Figure
7-40. This example consists of a low-permeability soil layer, an FML layer,
a surface water drainage system, and a soil cover layer capable of supporting
vegetation. Draft EPA guidance on final covers for hazardous waste landfills
recommends the following requirements (EPA, 1987a):
- The low-permeability soil layer should have a minimum thickness of 60
cm (24 in.) and a maximum in-place saturated hydraulic conductivity of
lO-/ cm s-l.
- The FML barrier should have a minimum thickness of 20 mils.
- There should be bedding above and below the FML.
- The drainage layer should have a minimum hydraulic conductivity of
10-2 cm s-l ancj a final bottom slope of 2% after settlement and
subsidence.
- The cover topsoil or vegetative layer must have a minimum thickness
of 60 cm (24 in.).
At the bottom of the cover system is the foundation layer which is
installed above the waste fill. This foundation should provide a stable
working and supporting surface on which the rest of the cover system can be
constructed. However, the stability of the foundation layer also depends on
the stabilization program implemented during filling of the containment unit
to prevent any large localized subsidence such as that generated by the col-
lapse of waste packages or soil bridges between packages, or by the presence
of cavities in the soil or rock beneath the waste.
7-104
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LJ.
Top Soil
(Slope > 2% after settlement)
FML
Operational
Cover
"9Ure 7"40' Lh"2™erP."ifiV,.0f a Cl°Sed "'"'""• («««• o" «ch.rt,on
by waste decomposition or other pro essesJ""1* dny gases
through a nser pipe that penetrate It HP r^ll «- ' y proper venting
escape to the atmosphere. Thus a ga ^ venMnn^^ al,]<\w the 9ases *°
pressure resulting from gas that mioht hmin 9 Sy,Stem (1) rell'eves any
barrier system, (2) controls the escaoe of t" Underneath the hydraulic
thelr collection. it should be "noted ?h^t L Se -gases • and ^3) allows
generation is not a problem at ha7,rdn? ?6 fn9lneers believe that gas
recommend that the c'over not be "^ tratlS tl lahndftlls- and' therefore
Gas-ventmg systems are necessary ? in MSW iJndfinl K * gas-*entl'n9 system.
resulting from the decomposition of wastes ?f6 9"S 9eneratio"
required, a filter layer between the founn" gas-contro1 layer is
•1" be retired. A schematic of a
s^
Northern and Truesdale, 1986) Controlled
in the unit is necessary because of ? the
ble, and/or malodorous gas 4 have on human
gas may be collected at the discharae ooTnt
incineration. Alternatively devices
the gas or incinerating the harmful
installed at gas discharge points
b^ Collection and/or
contai'nment units
gases ^cumulating
toxi'c» "mbusti-
envi>°^ent. The
transported for treatment or
1harmfu1 comPonents from
Place may be devised and
«nrf
7-105
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Steel Clamp
Boot
FML
Vent to Atmosphere
Boot Seal at FML
*— Filter
FML
Perforated
Pipe
Flange Seal at FML
T^^^^TT-TT
.'.'o.'-.'•«.';.'•'';/nV:'.•*;•'• °.'.''-'„'• '•*::"•'•'.* '*•'•*-''.'.'' Gas Venting
•'••'•'«''-' ' •''-•' •••"••'•''•.: »'..'' •'•.'••'' ••'• ".'. '• V Layer
Operational Cover
Figure 7-41.
Schematic of a gas-venting pipe system for a landfill
(Source: Richardson and Koerner, 1987, p V-16).
cover.
The low-permeability soil barrier can provide a base for an overlying
FML barrier and can provide long-term minimization of liquid infiltration
into the landfill by serving as a secondary hydraulic barrier in case the FML
barrier fails. The low-permeability soil barrier is designed and constructed
in much the same manner as the soil component of the bottom composite liner.
Potential soil materials need to be evaluated, a soil material selected, and
the procedure for constructing the soil barrier specified. Because the cover
system foundation may have a lower bearing strength than the soil liner
foundation, different equipment and procedures than those used to construct
the soil liner may be required. To prevent free-thaw damage to the con-
structed soil barrier, the liner can be required to be below the average
depth of frost.
The FML barrier prevents the surface water from passing through the
cover and infiltrating the underlying waste. Exposure conditions for an FML
in a cover system differ significantly from those for an FML in a landfill
lining system. The cover FML will not be exposed directly to leachate, but
it may be exposed to significant environmental conditions (e.g. freeze-thaw
cycling) and potential straining due to settlement within the waste mass.
The cover FML can be anchored in a trench that is placed beyond the trenches
in which the liner FMLs are anchored, as is shown in Figure 7-40. Special
7-106
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measures may be required to prevent water from entering the landfill between
the cover FML and the lining system. Some states (e.g. New York) presently
require the cover FML to be attached directly to the underlying FML liner.
At units exposed to significant surface water or potential subsidence,
the design engineer may require a double FML system with a leak collection
system between the two FML subcomponents of the final cover.
The surface water drainage system is designed to conduct away any
precipitation that infiltrates the top soil layer before it can penetrate the
barrier layers. This surface water needs to be diverted to a collection or
disposal system. Synthetic or granular drainage media can be used in design-
ing the surface water drainage system, which is similar in design to leachate
collection and removal systems. The important differences are that the
collected liquid is water and not leachate or a waste liquid and that the
overburden stresses on a surface water drainage system are much lower than
those on an LCRS underneath a containment unit. Either a granular or a
synthetic filter layer will probably be required above the drainage layer to
prevent the migration of fine particles in the surface layer into the drain-
age layer immediately below. The migration of these particles could plug the
drainage layer and render it ineffective.
The uppermost layer is called the surface or vegetative layer. Its
primary requirements are to (McAneny et al, 1985):
- Provide for vegetative growth.
- Minimize wind and rain erosion.
- Resist cracking.
- Resist freeze-thaw deterioration.
- Preserve slope stability.
- Provide protection from the elements for the layers below it.
- Provide a compatible host material for the site's surface water
management program.
- Provide an aesthetically pleasing appearance.
Topsoil specifications are likely to include properties (e.g. nutrient and
organic content) not required for the other soil components of the unit.
Soil specifications typical of the other earthwork components may also be
included, e.g. slope of the final cover surface.
The vegetation planted on the soil helps prevent erosion. In addition,
careful selection of short-rooted grasses is the most feasible method of
preventing plant roots from penetrating the underlying components of the
cover system, particularly the FML and the compacted soil barrier. Type of
7-107
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seed and rate of seed application, type of soil additive and rate of additive
application, filling depth, and watering instructions may be specified. In
arid areas of the country, where it is difficult to establish vegetation,
coarse materials such as cobbles and riprap may be used as protection against
erosion.
Depending on site specific conditions, additional layers may be required
to protect the barrier layers against burrowing animals (Johnson and Dud-
derar, 1988) and deep-rooted plants.
EPA (1987a), Johnson (1986a and b), Lutton (1982 and 1986), Lutton et al
(1979), McAneny et al (1986), and Richardson and Koerner (1987) discuss the
design of cover systems in more detail. Greathouse (1988) describes expert
systems that are being developed by the EPA to assist in reviewing closure
plans for land disposal sites.
7.6 REFERENCES
Barcelona, M., J. F. Keely, W. A. Pettyjohn, and A. Wehrmann. 1987. Hand-
book: Ground Water. EPA 625/6-87/016. U.S. Environmental Protection
Agency, Ada, OK. 212 pp.
Bass, J. 1986. Avoiding Failure of Leachate Collection and Cap Drainage
Systems. EPA 600/2-86/058 (NTIS PB 86-208 733/AS). U. S. Environmental
Protection Agency, Cincinnati, OH. 129 pp.
Boutwell, G. P., and V. R. Donald. 1982. Compacted Clay Liners for Indus-
trial Waste Disposal. Presented at ASCE National Meeting, Las Vegas,
NV. April 26, 1982. Cited in: Goldman, L. J., A. S. Damle, G. L.
Kingsbury, C. M. Northeim, and R. S. Truesdale. 1985. Design, Con-
struction, and Evaluation of Clay Liners for Hazardous Waste Facilities.
EPA 530/SW-86-007F. U.S. Environmental Protection Agency, Washington,
D.C. 575 pp.
Brown, K. W., J. C. Thomas, R. L. Lytton, P. Jayawickrama, and S. C. Bahrt.
1987. Quanitification of Leak Rates Through Holes in Landfill Liners.
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CHAPTER 8
SPECIFICATIONS FOR THE MATERIALS AND CONSTRUCTION
OF WASTE STORAGE AND DISPOSAL UNITS
8.1 INTRODUCTION
After developing the design of a waste containment unit, the designer/
engineer must prepare the necessary plans, technical specifications, and
drawings for the bid package and for use in constructing the containment
unit. In designing a containment unit, assumptions are made by the designer
about the quality of the materials of construction and the quality of work to
be performed during construction. Technical specifications and drawings are
necessary to communicate and clarify these assumptions.
As in all engineering projects, the preparation of good specifications
is essential to obtaining competitive bids and satisfactory construction
and to meeting the design goals of the project (Ebenhoeh, 1965; Goldbloom
and White, 1976). Incomplete drawings and specifications can result in
high-price bids, construction uncertainties, and inadequate product and
performance. It is not possible to prepare adequate performance specifi-
cations on such a complex product as a waste containment unit which must
meet many regulatory as well as site-specific requirements. Too many un-
certainties exist with respect to the performance of different materials,
and long periods of time are required to demonstrate effective performance.
As a consequence, the specifications must be based on accepted construction
procedures, stated property values for of the materials of construction used
in the project, which represent a consensus about the necessary values for
the particular construction materials, and quality control at all stages of
construction.
This chapter discusses the specification document prepared by a de-
signer/engineer, the different types of technical specifications, and ele-
ments of technical specifications for the different components of a lining
system. Particular reference is made to specifications for hazardous waste
containment units.
8.2 SPECIFICATION DOCUMENT
The designer/engineer prepares a document for the project for the
purpose of obtaining competitive bids for construction and to guide the
8-1
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successful contractor in the construction. This document includes three
major sections:
- A copy of the agreement between the owner and the contractor.
- The general conditions, if a general contractor is used, with special
conditions that pertain directly to the specific project.
- The drawings and technical specifications.
This chapter deals principally with the technical specification documents
that the designer prepares for the bid package. These specifications include
the drawings and specifications for the materials and workmanship.
The specification document incorporates the output of the design process
which probably includes the basic approval of the design by the appropriate
regulatory agencies. If the unit is to be used to contain hazardous mate-
rials or wastes, the design process will include a compatibility testing of
all components of the lining system with the waste stream to be contained,
as is required by EPA directive (EPA, 1986a). The technical specifications,
which are a written description, and the drawings, which constitute a dia-
grammatic presentation of the project, are complementary. The specifications
are addressed to the prime contractor and present the overall project in an
orderly logical manner. The specification document should be specific and
accurate in describing the requirements of the project; it should expand on
the notes and drawings, define the materials and workmanship, establish the
scope of work and state the responsibilities of the prime contractor.
By following the procedures and meeting the requirements set forth in
the specification document, the probability of meeting the project require-
ment of constructing an effective waste containment unit should be increased.
The technical specifications should include specific instructions for the
following as necessary:
- Site preparation and foundation.
- Embankments and other earthworks.
- Subgrade preparation.
- Drainage and gas venting systems.
- Leachate collection and removal systems.
- Appurtenances and penetrations.
- Liner construction (for soils, admixes, sprayed-on materials).
- Liner installation, particularly for field seaming of FMLs.
8-2
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- Quality control by the construction and installation contractors.
- Quality assurance by the owner or his representative.
Construction details are discussed in Chapter 9. Construction quality
assurance is discussed in Chapter 10.
8.3 TECHNICAL SPECIFICATIONS
There are five basic types of technical specifications which, in the
construction of waste containment units, tend to be used in combinations of
two or more. They are:
- Performance specifications.
- Descriptive specifications.
- Reference specifications.
- Proprietary specifications.
- Base bid specifications.
Performance specifications define the work to be done by specific results;
they give the contractor complete freedom to employ his knowledge and exper-
ience to carry out a particular project. At the present time, the basic
performance goal for a hazardous waste containment unit is to control the
escape of constituents so as to protect human health and the environment,
i.e. to allow no more than de mini mis leakage. Because the technology to
acnieve this goal is in the process of being developed, the EPA has promul-
gated, and is in the process of revising, minimum technology requi renc-nts
based on available technology as guidance for meeting the basic performance
specification. The minimum technology requirements are stated as descriptive
specifications. Nevertheless, specific components of a hazardous waste
containment unit may be specified on the basis of performance, e.g. the
capacity of pumps that might be used in the leachate collection and removal
systems.
Descriptive specifications define the scope of work for each base-
bid item of a project and describe the required properties of the materials
used in construction and the construction details for individual items. In
the case of a waste containment unit, descriptive specifications describe
the unit and the methods by which they are to be constructed; for example,
descriptive specifications are used in describing the construction and
quality control of the test fill, the earthworks, and the lower compacted
soil liner component of an FML/composite double liner. In the case of the
compacted soil liner, compaction of the soil can be described in terms of the
thickness of the lift and the type of equipment that is needed to obtain the
necessary permeability or strength of the soil. If a requirement for com-
patibility with the waste liquid or leachate is introduced, however, the
specific soil that has been tested for compatibility during the design
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phase would be specified. Generally, such a specification is avoided unless
it is backed up by a simulated performance requirement, such as a test
fill.
Reference specifications are standards for construction materials and
processes that have been developed by recognized authorities, including
professional engineering societies, government agencies, and industry as-
sociations. For example, standards for FMLs include those developed by the
American Society for Testing and Materials (ASTM), the American Society of
Agricultural Engineers (ASAE), and the National Sanitation Foundation (NSF).
Reference specifications or standards can be either used as a basis for
developing the descriptive specifications or incorporated directly into the
descriptive specifications. For example, an FML may be required to meet
NSF's specification for that type of FML. These types of standards are
generally used in conjunction with one or more of the other types of speci-
fications. For instance, in the case where an FML is required to meet NSF
specifications, it would also be required to meet a simulated performance
standard as indicated by a compatibility test and requirements for field seam
strength.
Proprietary specifications call for materials and components by trade
name, model or style number, and manufacturer. For example, such a specifi-
cation is used to specify a particular FML or liner system component in the
construction of a given hazardous waste containment unit if that FML is the
only one that has been tested and met specified criteria in an acceptable
compatibility test. This type of specification can also be used to specify
other components in leachate collection and removal systems. However, even
in cases in which a particular FML is specified, the technical specifications
will also include material property specifications for QA/QC inspection and a
fingerprint of the FML so that it can be demonstrated that the FML installed
at the site is the same as the one that passed the compatibility test. "Or
equal" materials cannot be used unless the specific materials have been
tested for compatibility as required.
Base-bid specifications establish acceptable materials of construction
by naming one or more materials so that the selection can be made by the
bidder or on the basis of cost. The bidder is usually required to prepare
his proposal with prices submitted from manufacturers and suppliers. How-
ever, if the materials are to be used in lining a hazardous waste containment
unit, they must all be tested for compatibility with the waste liquid to be
contained as part of the design process (EPA, 1986a). This compatibility
requirement includes FMLs, geotextiles, geonets, pipe, soils, and any other
components of the lining system that may come in contact with the waste
liquid or leachate.
8.4 SPECIFICATIONS FOR EARTHWORKS, EMBANKMENTS, AND SOIL
COMPONENTS OF FML/SOIL COMPOSITE LINERS
The purpose of construction specifications is to describe the quality
of work which is required to meet design requirements. Specifications for
embankment construction and other earthwork can incorporate language very
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similar to that used for standard dam construction. A set of sample specifi-
cations have been developed by the Bureau of Reclamation (Fink, Larkins, and
Lewandowski, 1977). These specifications are the result of many years of
earthwork construction and are a worthwhile starting point. However, the
incorporation of any standard specification should be approached with
caution because of potential differences in site conditions, materials
of construction, and overall design.
8.4.1 Specifications for the Foundation and Embankments
The basic difference in the performance requirement for embankments and
earthworks and that for the compacted soil liner, i.e. the lower component
of the bottom liner in a double liner system, is that the foundation and
embankments are constructed for strength and stability while the liner is
compacted to achieve low hydraulic conductivity. Therefore, the materials
required for embankments can include slag, ash, or rubble, so long as the
design can accommodate such materials, and proper installation techniques are
followed (Northeim and Truesdale, 1986 and Goldman et al, 1985).
The minimum elements of specifications for the foundation and embank-
ments are discussed in the following paragraphs.
8.4.1.1 Purpose of the Foundations and the Embankments--
The function of the foundation is to provide structural support to the
liner and all of its components for the operational life of the unit through
the post-closure care period. The purpose of an embankment is to function as
a retaining wall that resists the lateral forces of the stored wastes.
8.4.1.2 Material Specifications for Foundations and the Embankments--
Uniformity of materials with no soft or structurally weak components is
critical. Criteria for rejecting unsatisfactory materials and inspection
procedures should be stated. Examples of specifications for soil materials
include acceptable value ranges for various properties including particle-
size distribution, Atterberg limits, hydraulic conductivity of laboratory-
compacted soils, and moisture-density relationships.
Geogrids may also be included in the design for use in soil reinforce-
ment. Specifications for geogrids should include the following (Carroll,
1988):
- Geometry.
--Aperture size.
--Percent open area.
—Rib thickness.
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- Strength and dimensional stability:
--Long-term design load.
--Tensile modulus.
--Junction strength.
--Flexural rigidity.
8.4.1.3 Specifications for Excavation and Foundation Construction—
Strength requirements and the means for determining whether or not soils
meet design specifications should be defined. Any requirement for excavating
_i_n_ situ soils, and the placement and compaction of replacement soil in the
excavation should be stated.
8.4.1.4 Embankment Construction Specifications—
Construction of an embankment is generally performed by compacting a
specified material to a required strength at a specified moisture content
using a specified compactive effort to a specified dry density, all of which
have been correlated in laboratory testing during the design phase. Thus,
specifications for constructing the embankments will include construction
specifications and procedures for verifying construction performance. In
addition, the required slope and height, the placement of reinforcing mate-
rials (i.e. geogrids or geotextiles), and the method of construction (i.e.
whether the embankment should constructed in horizontal lifts, continuous
lifts, or a combination of both, depending on whether the embankment is
homogeneous or includes zones, or whether construction is performed on cut
slopes). Construction specifications should specify:
- Density.
- Soil water content.
- Lift thickness.
- Type and level of compactive effort, including:
--Type of roller.
--Weight of roller.
—Number of passes.
- Maximum clod size.
- Method for tying together the lifts.
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Procedures for verifying construction performance can include:
- Water content determinations.
- Density determinations.
- In-place strength tests.
Dimensions of the completed embankment should also be stated and supported by
the design drawings.
8.4.1.5 Requirement for Test Fill Construction to Verify
Embankment Design and Compaction Procedure—
Before constructing a hazardous waste containment unit, a test fill may
be required to verify that the specified soil density/moisture content/
compactive effort/strength relationships developed during the design phase
hold true for actual field conditions and to verify the adequacy of the
construction equipment and requirements for embankment construction. This
test fill can be constructed in conjunction with the test fill construction
of the soil component of the bottom liner for a double-lined unit. Because
of the importance of embankment strength, tests performed on the test fill
slopes should concentrate on confirming the relationship between moisture
content, density, and strength. The results of these tests should be cor-
related with the construction specifications, which may need to be revised
depending on the test results.
8.4.1.6 Specifications for Appurtenances--
Drainage systems, seepage control structures, and erosion control mea-
sures which may include berms, and/or vegetative covers should be included
in the specifications. Specifications for concrete, pipe, and related
materials for such adjunct structures should also be stated in the specifi-
cations.
8.4.1.7 Construction Quality Control and Assurance--
The specific actions that must be taken by the designer and construction
contractors to ensure that materials and workmanship are accurate and correct
and meet the specifications should be specified. All aspects of foundation
and embankment construction should also be covered by the construction
quality assurance plan, which is discussed in Chapter 10.
8.4.2 Specifications for Compacted Soil Component of a Composite
Bottom Liner of a Double Liner System
Except in cases where the conditions for statutory variance are met,
current RCRA regulations for the design of hazardous waste containment units
require two liners with a leak-detection system between the top and bottom
liner (40 CFR 264). The minimum elements included in technical specifi-
cations for the compacted soil liner component of a composite bottom liner in
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a double liner system are discussed in the following paragraphs. Much of the
information presented is also applicable to specifications for soil liners in
general.
8.4.2.1 Purpose of the Soil Component of a Composite Bottom Liner--
The function of the soil component of a composite liner is to control
constituent migration through breaches of the overlying FML component.
The liner should also provide support and function as a protective bedding
layer for the overlying FML component.
8.4.2.2 Material Specifications for the Soil Component of a Bottom
Composite Liner--
The specifications for the soil materials used in constructing the
compacted soil liner will reflect the properties of the soil selected as a
lining material and properties that will affect the performance of the com-
pacted liner. Requirements can include acceptable values or ranges for the
following properties:
- Hydraulic conductivity of laboratory-compacted soil.
- Soil density/moisture content relationships.
- Particle-size distribution.
- Atterberg 1imits.
In regions where swelling or other unusual soils are known to occur, or when
the liner may be exposed to extreme climatic conditions during or following
construction, additional property requirements can be included. A demonstra-
tion that the soil used in constructing the bottom soil component is com-
patible with the waste liquid to be contained may be required, depending on
the type of waste to be contained. If compatibility testing is required,
the specific soil that is tested must be well characterized, and the results
of this characterization incorporated into the materials specifications so
that it can be verified that the soil used in construction is equivalent to
the soil that was tested. The test method recommended by the EPA to verify
compatibility of the soil with the waste liquid or leachate to be contained
is EPA Method 9100 (EPA, 1986b), which determines the effect of the leachate
or waste liquid on the hydraulic conductivity of the compacted soil. It
should be noted that Method 9100 is currently (May 1988) under review.
Rejection criteria, test methods required to determine the properties, and
sampling requirements should be stated.
8.4.2.3 Requirements for Construction of the Soil Component
of a Composite Bottom Liner—
Construction of a soil liner is performed by compacting a specified
material at a specified moisture content using a specified compactive effort
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to a specified dry density. The various specified elements have been cor-
related with laboratory results obtained during the design phase to the
required saturated hydraulic conductivity. Construction specifications will
include:
- Overall thickness of the soil liner.
- Moisture content to produce the specified density.
- Specified dry density, which is usually expressed as a percentage of
the density obtained by testing in accordance with a specified test
method, e.g. 95% Proctor.
- Depth of the unit-layer to be compacted at one time, i.e. the lift
thickness.
- Surface preparation, e.g. scarification, for tying together lifts.
- Maximum clod size and uniformity of moisture content throughout the
soil at the time of compaction.
- Method of constructing the liner on the slopes, i.e. whether the liner
will be constructed in parallel or horizontal lifts.
- Type of compacting equipment.
- Weight of compacting equipment.
- Number of passes of compacting equipment over one unit-layer.
- Trade-name and model of the compacting equipment, if applicable.
Procedures for monitoring the construction of the liner should be stated in
the specifications. Included should be test methods to be performed on the
compacted soil, acceptable ranges for the results of these tests, sampling
requirements, and remedial actions that should be performed if the compacted
soil does not meet specification values (e.g. further compaction). Tests
that can be performed on the compacted soil include:
- Density.
- Moisture content.
- Hydraulic conductivity.
If field hydraulic conductivity testing is required as the basis for
accepting the liner (e.g. by a regulatory agency), a test fill will probably
be constructed, and the field hydraulic conductivity testing will be perform-
ed on the test fill liner. Test fills may also be required to verify that
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the materials, design (i.e. moisture content and density), equipment, and
construction procedures are adequate for constructing the full-scale soil
liner. If a test fill is required, construction specifications for the
compacted soil liner should be designed to replicate the product that was
accepted after evaluation of the test fill. The same construction materials
and methods used in constructing a successful test fill, including any design
modifications, should be used in constructing the actual liner. If the test
fill has been successful, then the actual liner should meet or exceed design
criteria, assuming quality control and quality assurance procedures are
rigorously followed.
Because of the general heterogeneity of soils, even from a single borrow
pit, and depending on the results of QA/QC testing, changes in some construc-
tion specifications (e.g. number of passes) may be required in the course
of construction so that a soil liner with the required permeability can be
constructed.
8.4.2.4 Requirement for Test Fill to Verify Soil Liner Specifications--
Present EPA Guidance on constructing hazardous waste landfills and sur-
face impoundments recommends contructing a test fill to verify the adequacy
of the materials, design, equipment, and construction procedures proposed
for the soil liner (EPA, 1985; Northeim and Truesdale, 1986). In addition,
regulatory acceptance of a soil liner may require the results of field
hydraulic conductivity measurements because of uncertainties about the
relationship between laboratory tests and actual in-place soil liner hy-
draulic conductivity. Because of the disadvantages in performing field
hydraulic conductivity tests on an in-place liner, constructing a test fill
before full-scale unit construction can be used as a method of assuring the
in situ hydraulic conductivity of the actual liner. Design specifications
for a test fill should duplicate those proposed for the full-scale unit. The
dimensions of the test fill and the measures taken to facilitate field perme-
ability testing should be stated. The test fill should be of sufficient
length to allow construction equipment to achieve normal operating speed over
a test area, and at least four times wider than the widest piece of construc-
tion equipment to be used (Northeim and Truesdale, 1986).
The results of the test fill construction can only be extrapolated to
the construction of the full-scale liner if the full-scale liner is con-
structed in accordance with the same design specifications, using the same
soil materials, construction procedures, and equipment that were used to
construct the accepted test fill. In addition, if field hydraulic conduc-
tivity testing of the compacted liner is specified as the method of verifying
that the actual liner meets the requirement for hydraulic conductivity, then
the results of the field hydraulic conductivity testing need to be correlated
with the construction parameters and the results of potential surrogate
tests, as is discussed in Section 7.5.3.1.5. Potential surrogate tests
include:
- Hydraulic conductivity of laboratory-compacted samples.
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- Hydraulic conductivity of undisturbed samples.
- Atterberg limits.
- Particle-size distribution.
- Compacted moisture content.
- Compacted soil density.
- Penetrometer strength tests.
In order for successful replication of the test fill to occur, it is
essential to observe, evaluate, and document the construction and evaluation
procedures used during test fill construction, and to incorporate what was
learned from test fill construction into the specifications. The need for
rigorous observation, evaluation, and documentation should be well understood
by designer, owner, inspector, and contractor before construction of the test
fill has begun.
The procedures by which the test fill construction is observed, evalu-
ated, and documented should be stated in the construction specifications,
with allowances made in advance so that any design and construction modi-
fications resulting from the test fill construction can be incorporated into
the specifications.
Northeim and Truesdale (1986) and Goldman et al (1985) discuss the de-
sign, construction, and evaluation of test fills for compacted soil liners
in more detail.
8.4.2.5 Requirements for Miscellaneous Components of the
Soil Liner and Earthworks--
Depth of sidewalls, width of berm, slope of embankments, liner thick-
ness, slope of liner along bottom of the unit, and requirements for trench
excavation in preparation of the installation of the leak-detection system
should all be stated in the specifications and supported by detailed design
drawings.
8.4.2.6 Acceptance of Soil Surface as Bedding for an FML--
Acceptance criteria, and the test methods by which to determine accept-
ability of the final product before the FML can be placed, should be des-
cribed in the specifications. In some situations, it has been the responsi-
bility of the FML installer to accept the bedding layer on which the FML
will be placed. Issues of concern will include desiccation cracking, holes,
defects, or areas of subsidence. The means by which to protect the liner
after completion of the final lift should also be specified, as should
methods by which to repair the liner should damage have occurred in the
course of construction operations.
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8.4.2.7 Construction Quality Control and Assurance--
Construction quality control and quality assurance procedures for the
compacted soil liner should be specified.
8.4.3 Specifications for the Compacted Soil Component of the
Upper Composite Liner of a Double Liner System
As is described in Chapter 7, a composite liner has been suggested as
the top liner in a double liner system for the containment of hazardous
wastes. In such a design, the soil component would have to be compacted on
top of the leak-detection system, which may either be a granular system or a
synthetic system made up of a combination of geonets, geotextiles, or geo-
composites. At present, specifications for the soil component of a top
composite liner with respect to either permeability or thickness have not
been fully described and documented. However, considerable care needs to be
exercised in constructing such a liner component in order to avoid damage
to the leachate collection and removal system between the liners, such as
intrusion of the soil into the system. Consequently, the construction method
should be carefully stated in the specifications. Double-liner designs with
a top composite liner should include test data verifying that a secondary
LCRS using synthetic drainage materials can perform adequately with the geo-
textile and clay above it. The elements that should be included in specifi-
cations for the compacted soil component of an upper composite liner of a
double liner system at a minimum are discussed in the following paragraphs.
8.4.3.1 Purpose of the Soil Component of a Composite Top Liner--
The function of the soil component of a composite top liner is similar
to that of the soil component in the bottom composite liner, which is to
reduce the leakage of the leachate through an overlying FML at the time of
a breach.
8.4.3.2 Material Specifications for the Soil Component of a
Composite Top Liner--
The material specifications for the soil component of a composite top
liner will probably be the same as those for the soil used in constructing
the soil component of the composite bottom liner.
8.4.3.3 Construction Specifications for the Soil Component of a
Top Composite Liner--
Since the soil component of a composite top lin^r is constructed on top
of the secondary LCRS, particular care must be exercised in placing and
compacting the soil. As is described in Chapter 7, the first lifts must be
applied without compaction and care taken to prevent damage to the secondary
LCRS. The upper lifts can be compacted, and the total depth and the hydrau-
lic conductivity of the lifts in immediate contact with the FML component of
the top liner should be stated, though the hydraulic conductivity may not be
as low as 10"? cm s~l. Specifications describing construction parameters
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will be similar to, if not the same as, those for the soil component of the
composite bottom liner.
8.4.3.4 Construction Quality Control and Quality Assurance--
Procedures for monitoring the quality of compaction should be specified;
in addition, observations and tests must be specified to assure that the top
surface of the soil is correctly finished, as is discussed in Section 8.4.4.
It may be desirable to construct a test fill on top of that used to test the
permeability of lower component of the bottom composite liner. This test
fill would assess the effect of the construction methods and equipment on the
LCRS underneath a top composite liner by assessing the transmissivity of the
drainage system after construction of the soil liner.
8.4.4 Specifications for the Subgrade Below an FML
General requirements for subgrade preparation and placement of a protec-
tive bedding layer for cushioning the FML, if required, should be stated in
the specifications. The specifications will depend on what is intended to
contact the FML in the design, e.g. a soil liner or a geotextile, and on how
the FML is being used, e.g. as the top component of a composite liner, as the
top liner in a double-liner system (i.e. indirect contact with the secondary
LCRS), or as a liner for a single-lined unit which is installed on top of
recompacted, in situ soil. Elements of specifications for an FML subgrade
are discussed in the following paragraphs.
8.4.4.1 Purpose of Bedding Layer for an FML--
The subgrade and protective bedding layer should support the FML and
protect it from irregularities in the foundation soils for the operational
life of the unit, as well as for the post-closure care period.
8.4.4.2 Material Specifications for a Bedding Layer for an FML--
Depending on the design of the unit, the materials used as the bedding
layer for an FML can include surficial foundation soils, the uppermost lift
of the soil component of a composite liner, and protective bedding materials
such as granular media and geotextiles. Requirement of the subgrade soil
with respect to maximum particle size, and the presence of debris and foreign
matter should be stated. Present EPA guidance recommends that the bedding
layer should have a minimum nominal thickness of 30 cm (12 in.) and an actual
minimum thickness of 25 cm (10 in.), that the bedding material should be no
coarser than Unified Soil Classification System (USCS) sand (SP) with 100% of
the washed, rounded sand passing the 0.25-in. sieve, and that the bedding
material is free of rock, fractured stone, debris, cobbles, rubbish, and
roots unless it can be shown that the FML will not be physical impaired by
the bedding material under service loadings (EPA, 1985). Also, if the bed-
ding layer contains seeds for vegetation that could affect FML performance,
the application of a herbicide may be required. However, it should be
demonstrated that the specified herbicide will not affect liner performance
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and groundwater monitoring results. If a geotextile is specified for pro-
tecting the FML, material specifications including strength requirements
should be stated. Performance specifications for each material and the test
methods to be used should be described.
8.4.4.3 Construction Specifications for a Bedding Layer--
Depth and extent of bedding materials should be stated. Criteria
relating to the foundations and embankments are discussed above. Techniques
for finishing the uppermost soil lift, which are described in Chapter 9,
should be covered. If a geotextile is specified, seaming methods should be
described.
8.4.4.4 Construction Quality Control and Quality Assurance--
Observations and tests required to determine that the subgrade has been
correctly finished and the bedding materials placed in accordance with the
final plans should be treated in both the quality control protocols and the
Construction Quality Assurance Plan. Proof rolling may be required before
the bedding can be accepted.
8.4.5 Specifications for a Protective Soil Cover
8.4.5.1 Purpose of a Protective Soil Cover--
A soil cover will serve as a protective cover for the FML or for the
primary LCRS, depending on the type of unit.
8.4.5.2 Material Specifications for a Soil Cover—
Soil properties should be stated. If there is a requirement for a
geotextile to protect the FML or act as a filter for the primary LCRS, the
properties of the geotextile should be stated.
8.4.5.3 Construction Specifications for a Protective Soil Cover—
Thickness of the protective cover material and the extent of coverage
should be defined. The soil cover should be placed very soon after instal-
lation and seaming is completed and the FML seams are tested; because of
potential damage to the uncovered FML, the length of time the FML is allowed
to remain uncovered may be stated. In addition, insofar as the placement of
the protective cover is a potential source of damage to the liner, methods by
which to protect the FML during this process and limitations as to what
types of earthmoving equipment may be used on top of the FML should be
stated in the specifications. Finally, methods of repairing damage to the
FML, should it occur, should be described.
8.4.5.4 Construction Quality Control and Quality Assurance—
Specific inspections and test procedures needed for both quality control
and quality assurance should be specified; also, the specific property values
that are acceptable should be indicated.
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8.5 SPECIFICATIONS FOR FMLS
FMLs can be used in numerous ways in the construction of a waste storage
or disposal unit including:
- As the FML component of a composite bottom liner of a double-liner
system for the containment of hazardous wastes.
- As FML top liner or the FML component of a composite top liner
of a double-liner system for the containment of hazardous wastes.
- As a single liner for the on-land storage or disposal of nonhazardous
materials.
- As the FML component of a cover system constructed on a landfill
during closure.
Correct specification, installation, and seaming of the FML is critical
to meeting performance requirements of an FML-lined waste storage or disposal
unit. Elements of technical specifications for FMLs are discussed in the
following paragraphs.
8.5.1 Purpose of an FML
The function of the FML is to form barrier that controls or minimizes
the migration of waste constituents from a waste containment for the op-
erational life of the unit including, in the case of landfills, the post-
closure care period.
8.5.2 Performance Requirements for an FML
In order to function sucessfully as a barrier, the FML has to meet
the following requirements:
- The FML must have sufficiently low permeability to the constituents
of the waste to be contained so that escape from the unit is below a
level that may pose a danger to human health or the environment.
- The FML must be chemically compatible with all constituents of the
waste to be contained, i.e. the waste must affect neither the FML nor
the seams in such a way that the FML is no longer able to fulfill its
function.
- The FML must be mechanically compatible with its service conditions.
- The FML must be sufficiently durable to maintain its integrity in the
service environment throughout its required service life, including
through the end of the post-closure care period.
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- The FML must be capable of being installed under a sufficiently broad
range of environmental conditions; in particular, the FML must be
capable of being seamed in such a way that the seams approximate the
strength and durability of the FML itself.
In addition, the expected service life of the FML should be stated in the
specifications. The operational life of a unit can range from less than one
year (in the case of some landfills units) up to 20 years; the post-closure
care period of a landfill is a minimum of 30 years.
If the wastes or materials to be contained are hazardous, compatibility
between the FML and the waste to be contained will need to be demonstrated to
the permitting agency. Thus, compatibility testing of the FML with the waste
or materials to be contained will need to be performed in accordance with an
acceptable test procedure, such as EPA Method 9090 (EPA, 1986b; Appendix L),
during the design phase (EPA, 1986a). The results of the compatibility test-
ing are incorporated in the permit application, and the FML is specified by
name and type. If two FMLs have demonstrated compatibility, both should be
listed in the specifications.
The fingerprint of the FML that has passed the compatibility test should
also be included in the specifications so that it is possible to demonstrate
that the FML being placed in the field is equivalent to the FML that was
tested for compatibility. In cases where the owner/operator has performed a
compatibility test with a particular FML to meet the compatibility require-
ment, but proposes to install an FML of the same type as made by a different
manufacturer or of a different "batch" or formulation, EPA presently requires
that he either demonstrate that the alternate FML is compatible by further
compatibility testing or that the alternate FML is essentially equivalent to
the FML that was originally tested by comparing the fingerprints of the two
materials (EPA, 1986a). However, the EPA recognizes that choosing the second
option will present difficulties because there will need to be agreement on
the testing program and interpretation of the test results. Fingerprinting
of FMLs is discussed in Section 4.2.2.6.
8.5.3 Material Specifications for FMLs
The properties of an FML can be covered by a large number of different
specifications, ranging from those prepared by the FML manufacturer, instal-
ler, and the designer/engineer, to reference specifications developed by
various organizations such as ASTM, NSF (1985), and the American Association
for Agricultural Engineers. The designer/engineer, however, selects the
specific set of specifications to meet the material requirements of a speci-
fic site and includes these specifications in the design. The requirements
can vary with the particular type of containment unit that is being de-
signed and the type of waste stream that is being contained. In addition,
the property specifications will depend on the type of FML that has been
selected.
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Ideally, selecting proper material specifications for an FML should
ensure that the selected FML will also meet the performance requirements as
stated in Section 8.5.2. However, there is no simple correlation between any
one property (e.g. uniaxial tensile strength) and ultimate liner performance.
Further field verification testing of in-service FMLs is required before a
correlation between FML properties and performance can be developed with any
confidence. Thus, no single property or set of property values should be
used as a basis for selecting one type of FML over another except in cases
where incompatibility with the waste to be contained or incompatibility with
the engineering application is demonstrated. In setting the specifications,
the designer should be aware that some properties are specified to help
ensure that the selected FML will meet the performance requirements and that
some are specified to ensure the quality of the selected FML given that a
generic FML type has been selected. Those properties specified to ensure the
quality of the FML form the basis of the QA/QC testing.
Depending on the type of FML that was selected, properties that may be
included in the material specifications can include, but are not limited to:
- Analytical properties:
--Volatiles.
--Ash content.
--Extractables.
--Specific gravity/density.
--Crystallinity content (if FML is semicrystalline).
--Carbon black content.
--Melt flow index (if FML is semicrystalline).
- Physical properties:
—Thickness.
--Tensile properties.
--Modulus of elasticity (if FML is semicrystalline).
—Hardness.
--Tear resistance.
--Puncture resistance.
--Hydrostatic resistance.
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--Scrim chracteristies (if FML is fabric-reinforced).
--Ply adhesion (if FML is fabric-reinforced).
- Seaming characteristics:
--Strength of factory-prepared seams.
—Strength of field-prepared seams.
- Permeability characteristics:
—Water vapor transmission.
—Solvent vapor transmission.
--Gas permeability.
- Tests that measure environmental and aging effects:
--Resistance to ozone-cracking.
--Resistance to environmental stress-cracking (if FML is semi-
crystalline).
--Low-temperature properties.
--High-temperature properties.
—Air-oven aging characteristics.
--Dimensional stability.
—Water absorption.
—Resistance to soil burial.
These properties and specific tests for measuring them are discussed in
Section 4.2.2.5.
Appendix K presents suggested reference standards for a variety of FMLs
that are currently available. These property values do not reflect compati-
bility with the specific waste nor other site specific requirements. How-
ever, these specifications can be used for the quality assurance at the time
the containment unit is constructed.
Other specifications of FMLs may include specifications for the raw
materials constituents of an FML of a given polymer type. In the case of an
FML for a hazardous waste containment unit, the fingerprint of the selected
FML which has passed the compatibility test should be incorporated in the
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specifications so that it can be demonstrated that the FML being placed in
the field is equivalent to the FML tested for compatibility.
8.5.4 Specifications for Shipping and Storage of FMLs
Specific requirements for labeling, shipping, and on-site storage for
the FML should be described in the specifications. Exact requirements will
vary with the FML type.
FMLs are usually shipped and stored in rolls or folded on pallets.
Depending on the polymer, particular attention may need to be paid to high
temperature and other environmental conditions during storage prior to
shipment, during shipment, and at the site prior to installation. Some FMLs,
e.g. those based on CSPE and CPE, are sensitive to moisture and heat; these
FMLs can partially crosslink (making the FML more difficult to seam) or block
under improper storage conditions before being installed in the field. In
addition, some FMLs may need to be protected from heat and sunlight to
prevent the volatilization of plasticizer.
Depending on the type of FML, identification of the manufactured rolls
or fabricated panels should include the following:
- Name of manufacturer/fabricator.
- FML type, including polymer type and details of contstruction (e.g.
number of plies, type of scrim, nominal thickness, etc.).
- Manufacturing batch code (of rolls).
- Panel number or placement according to the design layout pattern.
- Date of manufacture (of rolls) or date of fabrication (of panels).
- Physical dimensions (length and width).
- Directions for unrolling or unfolding of the FML.
Storage facilities for the FML should be secure so as to prevent ac-
cidental damage (e.g. by animals) or damage by vandalism. In addition,
storage facilities should protect the FML from dirt, dust, water, and
extreme heat. In cases where the FML will be stored in direct contact with
the ground, the surface should be relatively level, smooth, and free of
rocks, holes, and debris.
8.5.5 Installation Specifications for an FML
The placement plan for the liner panels or rolls should be incorporated
into the design drawings, which are then referenced in the specifications.
Temperature and weather limitations for high quality installation and seaming
of the particular FML should be specified, and the type and quality of field
seams should be described. Depending on the type of FML, specifications for
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seaming could include the overlap between panels, required preparation of the
FML prior to seaming, the cleanliness required for seaming operations, and a
description of the seaming equipment for the specific FML. A description of
the base, e.g. a board, on which to prepare the field seams using solvent-
based adhesives and the pressure and dwell time for proper formation of both
adhesive and thermal seams can also be included in the specifications.
Methods for assuring that the quality of workmanship called for in the
specifications is actually met in the field installation should be defined in
the construction quality control and assurance plans (see Chapter 10). The
specifications should include specific criteria for acceptance/rejection of
seams depending on the results of nondestructive as well as destructive
tests; for the latter, specific types of breaks that are allowed as well as
the minimum values for seam strength resulting from testing in accordance
with a specified test method should be incorporated into the specifications.
The number of specimens per sample that must be tested and the maximum number
of allowed failures for a given sample also should be specified.
8.5.6 Specifications for Sealing the FML to Penetrations
and Appurtenances
When penetrations through the lining system (as for structures and
pipes) are included in the design, they should be detailed in the drawings,
and requirements for their installation and sealing should be described in
the specifications. The materials (e.g. pipe boots and sealing compounds)
should be described, as should the installation techniques. Since the
mechanical compatibility of materials for appurtenances with the FML can be
critical, these materials require careful definition in the specifications.
8.5.7 Specifications for Anchoring the FML
The FML is usually anchored by the FML installer. Design of the anchor
trench should be detailed in the design drawings, and any special require-
ments for construction and backfilling of the anchor trench should be des-
cribed. A requirement for ensuring that all objects placed adjacent to the
FML are smooth and will not cause undue wearing, penetration, or tearing of
the FML should be stated in the specifications and supported by the CQA
plan.
8.5.8 Construction Quality Control and Quality Assurance
Conduct of inspection activities and both nondestructive and destructive
seam testing during this phase of construction will provide a reasonable
degree of certainty that the FML will meet or exceed performance criteria.
Tests of FMLs and FML seams are discussed in Section 4.2.2.5.
8.6 SPECIFICATIONS FOR LEACHATE COLLECTION AND REMOVAL SYSTEMS
Leachate collection systems and removal systems (LCRSs) can contain a
wide variety of components. The complexity of the LCRS will vary depending
upon the design, but each component that is designed into the systems will
require discussion in the written specifications. The different types of
LCRSs are discussed in Chapter 7.
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8.6.1 Purpose and Performance Requirements
The purpose of an LCRS is to collect all liquids that enter the system
and remove them for treatment, re-use, and/or disposal. LCRSs are used in
controlling the hydraulic head on a liner and in leak detection. For a
hazardous waste landfill, the EPA presently requires two LCRSs, including a
primary system placed above the top liner and a secondary system placed
between the two liners. The function of the primary LCRS is to minimize the
leachate head above the top liner during operation of the unit and to remove
liquids that are generated by the system through the end of the post-closure
care period. The LCRS should be designed to keep the leachate head on the
liner below a predetermined level which, in present EPA guidance, is a
maximum of 1 ft. This requirement should be stated in the specifications.
Furthermore, an LCRS will be required to have a service life equal to that of
rest of the containment system. This will require that drainage and filter
materials meet performance specifications for transmissivity and/or hydraulic
conductivity. In addition, performance requirements for sump capacity and
for mechanical equipment such as pumps, levels, and monitoring equipment
should be stated.
The secondary LCRS is separate from the primary LCRS and acts as a
leak-detection system to indicate that a breach has occurred in the top
liner. This system must have a high transmissivity which is specified and a
specified detection time, which is the time between when liquid enters the
system and the appearance of liquid in the sump for that LCRS. In addition,
the bottom slope of the LCRS should be specified. In permit applications, it
may be necessary to demonstrate that the specified design is adequate for
meeting the detection time requirement using a combination of modelling and
experimental data.
Hazardous waste surface impoundments and waste piles have secondary
LCRSs which have the same performance specifications as those for secondary
LCRSs in a hazardous waste landfill.
In designing LCRSs with synthetic drainage media, test data for trans-
missivity should accompany the specifications demonstrating that the speci-
fied system can meet the performance specifications, particularly in the case
of a secondary LCRS that will be installed underneath a clay liner. Testing
should be performed using the boundary conditions that are specified in the
design.
In addition, where granular materials are in contact with a perforated
pipe, the adequacy of the perforations in relation to the grain size of
the drainage media should be demonstrated.
As materials used in an LCRS either will be or may be in contact with
the leachate or waste liquid to be contained, all materials used in an LCRS
for a hazardous waste containment unit need to be tested for compatibility
with the waste liquid or leachate during the design process as is required by
EPA directive (EPA, 19865). Compatibility testing of the granular components
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of an LCRS includes determining whether the soil materials will dissolve or
form a precipitant that would clog the LCRS when in contact with the waste
liquid or leachate to be contained. Compatibility testing of the polymeric
components of an LCRS involves exposing the materials in accordance with EPA
Method 9090, which determines FML-waste compatibility, and comparing the
results of testing the exposed material with the results of testing the
unexposed material. Suggested testing includes testing the piping for
strength (e.g. ASTM D2412), geotextiles intended for FML protection for grab
strength (e.g. ASTM D1682) and puncture resistance (e.g. ASTM D751), and
drainage materials for load deformation/transmissivity characteristics (e.g.
ASTM D4716). In using transmissivity testing to determine compatibility, the
EPA presently recommends the following test conditions (EPA, 1986a):
- The final pressure on the drainage material should be at least 1.5
times the maximum expected pressure to be experienced during the
active life and post-closure care period of the unit.
- The drainage material should be tested in the transmissivity under
expected field conditions, i.e. both sides of the drainage material
should be contact with the materials with which it will be installed
in the field (e.g. soil, sand/gravel, FML, or geotextile).
The polymeric materials should then be fingerprinted to ensure that the
actual materials used in the construction are those that were tested in the
compatibility tests. After a polymeric material has been selected, shown to
be compatible, and fingerprinted, the specific name and style of the material
and the fingerprint should be incorporated in the specifications. Section
4.2.2.6 presents a protocol for fingerprinting FMLs which is also applicable
to characterizing all polymeric materials used in an LCRS.
8.6.2 Material Specifications for an LCRS
An LCRS is typically comprised of a number of subcomponents including:
- A drainage layer.
- A filter layer.
- A pipe network for collecting leachate or waste liquid from the
drainage layer and transporting it to the sump/manhole system.
- A bedding layer for the pipe network.
- A sump/manhole system which allows collection of the leachate or waste
liquid and access to the pipe network for inspection and possible
repairs throughout the monitoring periods.
Mechanical and electrical equipment for
collection system to a separate storage
monitoring and controlling the level of
conveying liquid from the
or treatment area and for
leachate above the liner.
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The materials used for these various subcomponents varies from design
to design and can include granular materials, geonets, geotextiles, geo-
composites, and plastic pipe. Each type of material will have its own set of
specifications, which may also depend on the intended use of the material.
Specifications for pipe can include:
- Composition.
- Dimensions, including inside diameter, outside diameter, and wall
thickness.
- Perforation size and spacing (if applicable).
- Specific gravity/density.
- Tensile strength.
- Modulus of elasticity.
- External loading properties.
- Coefficient of linear expansion.
Reference standards, such as the consensus developed by the Plastic Pipe
Institute (Society of the Plastics Industry, 1979), NSF (1977), and ASTM
(1988), can also be cited for specifying pipe.
Specifications for geotextiles can include:
- Dimensional properties:
—Thickness.
--Mass per unit area.
- Permeability/filtration properties:
--Percent open area.
--Equivalent opening size.
--Permittivity.
- Mechanical properties.
--Puncture resistance.
--Trapezoidal tear strength.
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--Mullen burst strength.
--Tensile properties.
- Durability characteristics:
—UV resistance.
Specifications for geonets and other synthetic drainage media can include:
- Thickness.
- Standard crush strength.
- Load deformation/transmissivity characteristics.
Specifications for granular drainage media can include:
- Particle-size requirements.
- Hydraulic conductivity.
- Sensitivity to acids.
8.6.3 Construction Specifications for an LCRS
Because of the range of possible designs, the construction specifi-
cations will vary from site to site and design to design. A leachate col-
lection system, particularly the collection pipe network, may require bedding
which can also be a granular drainage media. The horizontal and vertical
alignment of the foundation required to ensure that the leachate will flow
toward the sump should be illustrated in the design plans and specified.
Pipe layout and placement condition, as well as the location of riser pipes,
manholes, and sumps, should be detailed. Methods and materials by which to
join the pipes and seam the geonets and geotextiles should be stated. The
requirement for the placement of filter materials, and wrapping of pipes, if
required, should also be specified. Placement of the drainage layer, thick-
ness of the layer, and degree of compaction should be stated, as should
backfilling methods. It may also be necessary to verify the alignment of the
pipe prior to backfilling. Synthetic drainage materials will have special
requirements which should be stated in the specifications. These materials
are discussed in Chapters 4 and 7. Installation of the mechanical components
is usually the final activity performed during construction of the LCRS.
Design specifications and manufacturers' recommendations for these components
should be incorporated into the specifications.
8.6.4 Construction Quality Control and Quality Assurance
The observations and tests that are necessary to provide a reasonable
degree of certainty that the LCRS and its components will meet or exceed
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design criteria for the required service life of the facility should be
detailed in the construction quality assurance plan.
8.7 SPECIFICATIONS FOR FINAL COVER SYSTEMS
A final cover system is constructed on top of a landfill at the end of
the active life of the unit, i.e. at the time of final closure. The active
life of landfill units can vary from less than 1 year to more than 10 years.
In general, construction of the final cover will be performed under a con-
tract separate from the one used for construction of the lining system.
Lutton (1986) describes the design, construction, and maintenance of cover
systems and presents several specific examples of specifications that could
be followed for different designs of cover systems. These specifications
follow, in many respects, the procedures used by highway engineers in the
construction of embankments in view of the similarity of placing a cover
system on backfilled solid waste and that of a pavement system on an em-
bankment subgrade. Cover systems consist of a series of layers including
soils and other materials such as FflLs and geotextiles, as is described in
Section 7.5.8 and by Lutton (1986) and McAneny et al (1985).
8.7.1 Purpose and Performance Specifications for a Cover System
The purpose of the cover system is to minimize the generation of leach-
ate within the landfill during the post-closure care period and beyond by
preventing the intrusion of liquids into the landfill. The cover should also
control gases that may be generated within the fill, function with minimum
maintenance, accommodate settling and subsidence, promote drainage, minimize
erosion, and allow a transmission of liquids at a rate less than or equal to
that of the underlying liner.
The final cover is similar to the lining system in that both consist
of a number of different components, which must all function properly and
maintain their integrity if the system as a whole is to function adequately.
Cover systems typically can consist of:
- A vegetative layer.
- A filter layer.
- A drainage layer.
- A barrier (or low-permeability) layer.
- A gas-control layer.
Not all of these layers are present in all systems depending on the particular
design, the type of waste disposed of in the fill, and other site-specific
conditions. Each layer will have its own performance requirements. The
vegetative layer should be capable of allowing surface runoff from major
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storms without formation of erosion rills and gullies. The filter layer
should prevent the vegetative layer soil from entering the drainage layer.
The drainage layer should remove water that has infiltrated through the
vegetative layer as to minimize infiltration into the barrier layer. The
barrier layer should provide long-term control of the migration of liquids
into and through the closed disposal unit. In cases where a unit is expected
to generate gases, a gas-control layer with a venting system will be included
in the design to relieve pressure resulting from the buildup of gases, to
control the escape of these gases, and to allow their collection.
8.7.2 Specifications for the Components of a Cover System
The construction of and the materials used in the consruction of a final
cover system are similar to those of a lining system. Many of the construc-
tion and materials specifications will be similar to specifications for the
different components of a lining system. One important difference is that
the components of a cover system will not come into direct contact with
constituents of the waste, with the possible exception of volatile organic
compounds present in the landfill gases; thus chemical compatibility with the
waste leachate is not a performance requirement for components of the cover
system.
8.7.2.1 Specifications for a Gas-Venting System--
The design of a gas-venting system will be similar to that of an LCRS
except that, instead of collecting liquids that drain to the bottom of the
system, gases that rise to the top of a gas-control layer are collected and
allowed to exit the system via vents. The performance requirements for
flow through the system should be specified as well as the technical design
requirements. In the case of a granular system, the specifications could
include:
- Hydraulic conductivity.
- Thickness of layer.
- Particle-size distribution.
- Slope of the overlying barrier layer.
- Pipe specifications, including sizing and spacing and sizing of the
perforations for the collection pipes.
- Bedding of the pipe and its depth in the drainage layer.
- Location of the venting riser pipes.
In addition, a filter layer will probably be required both above and below
the system. Filter properties should be stated, and the properties of the
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selected filter materials should be specified. The method of constructing
the system, including the types of equipment that should be used should be
stated.
8.7.2.2 Specifications for the Low-permeability Layer—
The low-permeability layer will consist of either compacted clay or a
composite clay-FML liner. Specifications for this layer will be very similar
to those for the comparable components of a lining system. Construction of
the soil component is performed by compacting a specified soil material at a
specified moisture content using a specified compaction procedure in order to
achieve a specified hydraulic conductivity. Elements of specifications for
soil materials and the construction of soil liners are discussed in Section
8.4.2. Important differences will include the level of the soil liner in
relation to the average depth of frost and a requirement for the upper slope
of the liner. The specifications for an FML component will be similar in
form to those for an FML liner. FML specifications are discussed in Section
8.5. The method by which the cover is anchored in relation to the underlying
liner system should be detailed.
8.7.2.3 Specifications for Drainage Filter Layers-
Specifications for the combined drainage and filter layers will be
similar to those for primary LCRSs in a landfill. Elements of specifications
for LCRSs are discussed in Section 8.6. Specifications should include
requirements for:
- Hydraulic conductivity (in the case of granular media).
- Transmissivity under compressive loading (in the case of synthetic
drainage media).
- The final bottom slope.
- Thickness of the layer (in the case of granular media).
8.7.2.4 Specifications for the Vegetative Layer—
The design of a vegetative layer will depend on a number of site speci-
fic conditions. Various elements of specifications for vegetative layers
will include:
- Thickness of the overall layer. If more than one soil has been
specified, the thickness of each soil type.
- Characteristics of the soil, including pH characteristic, organic
content, grain-size characteristics, and requirements for nutrients.
- Requirements for placement and compaction of soil materials, including
methods of placing the soil, loose lift thickness, the required
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density (stated as a percent of maximum density determined in accord-
ance with a standard method), and methods of inspecting the construc-
tion procedures.
- Final slope of the cover.
- Requirements for surface drainage systems for routing run-off.
- Procedures for establishing the vegetation on the top of the cover,
including:
--Materials to be used, i.e. type of fertilizer, seed, and
mulch.
—Seeding schedule.
--Soil preparation prior to seeding.
--Methods of applying seed, fertilizer, and mulch.
- If a nonvegetative cover has been specified (e.g. riprap), then the
characteristics and the requirements for placing the top layer of the
cover.
- A maximum rate of erosion (EPA, 1987).
8.8 REFERENCES
ASTM. 1988. Annual Book of ASTM Standards. American Society for Testing
and Materials, Philadelphia, PA:
Volume 1.01: Steel—Piping, Tubing, Fittings.
Volume 8.04: Plastic Pipe and Building Products.
(Note revisions are issued annually.)
Carroll, R. 1988. Specifying Geogrids. Geotechnical Fabrics Report
6(2):40-43.
Ebenhoeh, J. F., Jr. 1965. Specifications. In: Building Construction
Handbook. Merritt, F. S., ed. 2nd ed. McGraw-Hill, NY.
EPA. 1985. Minimum Technology Guidance on Double Liner Systems for Land-
fills and Surface Impoundments—Design, Construction, and Operation.
EPA/530/SW-85-014. Draft. U.S. Environmental Protection Agency,
Washington, D.C. 71 pp.
EPA. 1986a. Supplementary Guidance in Determining Liner/Leachate Collection
System Compatibility. EPA Directive 9480.00.13, August 7, 1986. Office
of Solid Wastes and Emergency Response, U.S. Environmental Protection
Agency, Washington, D.C.
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EPA. 1986b. Test Methods for Evaluating Solid Waste. Vol. 1A: Laboratory
Manual, Physical/Chemical Methods. 3rd ed. SW-846. U.S. Environmental
Protection Agency, Washington, D.C.
EPA. 1987. Minimum Technology Guidance on Final Covers for Landfills and
Surface Impoundments. Draft. EPA Contract No. 68-03-3243, Work Assign-
ment No. 2-14. U.S. Enivronmental Protection Agency, Washington, D.C.
31 pp.
Fink, R. E., N. F. Larkins, and E. R. Lewandowski. 1977. Sample Specifi-
cations. In: Bureau of Reclamation. 1977. Design of Small Dams. 2nd
ed., revised reprint. U.S. Government Printing Office, Washington, D.C.
pp 667-765.
Goldbloom, J., and J. J. White. 1976. Specifications. In: Standard Hand-
book for Civil Engineers. F. S. Merritt, ed. 2nd ed. McGraw Hill, NY.
pp 3/1-23.
Goldman, L. J., A. S. Damle, G. L. Kingsbury, C. M. Northeim, and R. S.
Truesdale. 1985. Design, Construction, and Evaluation of Clay Liners
for Hazardous Waste Facilities. EPA/530-SW-86-007F. U.S. Environmental
Protection Agency, Washington, D.C. 575 pp.
Lutton, R. J. 1986. Design, Construction, and Maintenance of Cover Systems
for Hazardous Waste—An Engineering Guidance Document. U.S. Environ-
mental Protection Agency, Cincinnati, OH. 183 pp.
McAneny, C. C., P. G. Tucker, J. M. Morgan, C. R. Lee, M. F. Kelley, and R.
C. Horz. 1985. Covers for Uncontrolled Hazardous Wastes Sites.
EPA-540/2-85-002. U.S. Environmental Protection Agency, Cincinnati,
OH.
National Sanitation Foundation (NSF). 1977. Standard Number 14: Thermo-
plastic Materials, Pipe, Fittings, Valves, Traps, and Joining Materials.
Rev. Standard. National Sanitation Foundation, Ann Arbor, MI.
National Sanitation Foundation (NSF).
Membrane Liners. Rev. Standard.
Arbor, MI.
1985. Standard Number 54: Flexible
National Sanitation Foundation, Ann
Northeim, C. M. and R. S. Truesdale. 1986. Technical Guidance Document:
Construction Quality Assurance for Hazardous Waste Land Disposal Facil-
ities. EPA 530-SW-86-031. OSWER Policy Directive No. 9472.003. U.S.
Environmental Protection Agency, Washington, D.C. 88 pp.
Society of the Plastics Industry. 1979. PPI Technical Report: Standards
for Plastics Piping. TR5/12-79. The Society of the Plastics Industry,
New York, NY. 18 pp.
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CHAPTER 9
CONSTRUCTION OF LINED WASTE STORAGE AND DISPOSAL UNITS
9.1 INTRODUCTION
In the construction phase of a project, design plans and specifications
are converted into the actual waste storage or disposal unit. The construc-
tion contractor is responsible for constructing the unit in strict accordance
with the design criteria, plans, and specifications that have been approved
by the owner and the permitting agency. As part of the contractual arrange-
ment made with the unit owner/operator, the contractor may be required to
include the formulation and implementation of a formal plan for construction
quality control.
This chapter discusses various steps in constructing the major compo-
nents of both hazardous and nonhazardous waste containment units and several
of the subcomponents that require special attention; construction and in-
stallation of the following components are discussed:
- Earthworks, including excavation and construction of the foundation,
the embankment, and the soil component of a composite liner.
- FMLs.
- Leachate collection and removal systems.
- Final cover system.
Discussion of soil
a composite liner.
liners in detail.
FML installation,
admixed liners.
9.2 EARTHWORKS
liners is limited to their construction as components of
Goldman et al (1985) discuss the construction of clay
This chapter also discusses special considerations in
such as around appurtenances, and the construction of
In this section, the construction of the earthwork components of storage
and disposal units are discussed. Earthwork construction begins with ex-
cavation and preparation of the foundation and includes construction of the
soil component of a composite liner. The different components serve different
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functions. These components will have different specifications, pose dif-
ferent construction problems, require different construction techniques,
and require different types of quality control inspections.
In most instances, the earthwork is performed by a general engineering/
construction contractor. The types of equipment used vary with the size
and complexity of the job. Basically, equipment used in constructing
waste storage or disposal units can be grouped as excavators, earthmovers,
compactors, and special equipment. Small impoundments may require only
tractors with dozer blades, water trucks, and compactors, while large jobs
may require additional vehicles including side loaders, graders, trucks,
backhoes, front end loaders, trenching machines, and conveyor systems
(Figures 9-1, 9-2 and 9-3). Sources of general information on earthworks
include Gregg (1960), Sain (1976), and Church (1981).
9.2.1 Excavation and Foundation Construction
Depending on the type of unit, its size and configuration, and the site
location, the amount of excavation and site preparation will vary. If
groundwater is encountered during excavation resulting in a significant
amount of surface water, problems may develop that can adversely affect the
subsequent liner installation. The presence of free standing water in the
excavation will not only hinder the work of heavy equipment, but also will
severely hamper construction of the soil component of a bottom composite
liner. Similarly, rainfall can hinder excavation activities and, in some
cases, halt work by creating adverse traffic conditions. If free water
persists at the base, a special base may have to be constructed. Gravels of
various sizes can be packed into the earth, then covered with sand or other
available material such that a stable, firm working surface for later grading
is achieved. Costs are greatly increased by the need to build a water-free
surface for an FML installation in wetted areas.
During the excavation process, all vegetation (tree trunks and roots,
in particular) and large rocks need to be removed from the site. In general,
the upper 3 to 12 in. need to be removed at a minimum. This soil, which can
be used elsewhere in the unit for miscellaneous construction purposes, may
shrink 5 to 20% between excavation and use. Any depressions resulting from
removing stumps, boulders, or similar conditions need to be filled in with
suitable backfill.
Slopes will be constructed by usual techniques. Most construction
equipment, including self-propelled compacting rollers, can be operated on
slopes up to 3:1 during normal conditions. However, during periods of
precipitation, additional arrangements may be needed to ensure that equipment
can travel safely up and down slopes, even 3:1 slopes. A simple link to
a large dozer, another heavy piece of equipment, or a winch stationed at the
top of the sidewall/berm can be used. The equipment at the top then helps to
pull the working unit up the slope, and helps to retard its down slope pro-
gress on the return trip.
9-2
-------
•*s
Figure 9-1. Typical earthwork equipment used during impoundment construc-
tion: dozer with blade (top) and dozer with compactor and
blade (bottom).
9-3
-------
,,„ #B*!v-i^«|»/*>, j fa
VfV-"/.'S, ,<*
-------
* *•».- .
1>* .V. ,»« Lsfc't,
"tl!^*^
^-^:
'**>•
Figure 9-3. Conveyor system used during earthwork construction.
When the side slope is steeper than 2:1, the "helping hand" approach is
mandatory. One method is to chain two similar pieces of equipment together
for cross slope work, such that the "helper" traverses the flattened top of
the embankment while its chainlinked "twin" works the slanting side slope.
Of course, extreme care must be observed during operations of this type.
Road graders or vibrating rollers linked side-by-side by chain are examples
of the types of equipment that might be used in this manner.
9.2.2 Compaction of Soil
Compacting soil materials is an essential element in constructing
components of all types of lining systems, whether they be soils for the
clay soil component of a composite liner or for a subgrade on which admix or
sprayed-on liners will be installed. Regardless of whether compaction is
being performed to increase the strength or decrease the hydraulic con-
ductivity of a soil, in the earthwork construction, the soil materials are
usually compacted at a specified moisture content to achieve a miminum
density. This density is usually stated as a percentage of the maximum dry
density achieved by compacting the soil in accordance with a standard method,
e.g. Standard Proctor. The compactive behavior of soils is presented sche-
matically in Figure 9-4 as a function of moisture content. This figure shows
a range of water contents at which the soil can be compacted to achieve the
target density, given the specific compactive effort. Water contents outside
this range will need to be adjusted to achieve the target density. Strict
9-5
-------
control of water content is essential to achieving the target density and,
in the case of soil liners, the specified hydraulic conductivity. The
compactive behavior of soils and its relationship to soil properties is
discussed in more detail in Section 7.5.3.1.2.
d max Maximum density at the compactive
effort used, e.g. Standard Proctor
' d tar Target density as a percentage of
maximum density, e.g. 95% Standard Proctor
Optimum water content
&
^
D
"6
CO
Water needs
to be added
Water content range
in which T
-------
strength for stability. Some FML manufacturers have indicated that they
believe soil materials should be compacted to 90 to 95% Proctor to achieve a
firm, unyielding base for an FML.
In this subsection, field compaction of soil, the equipment, and the
field tests required in the construction of lined waste disposal containment
units are described. For further discussion of field compaction and tests of
compaction see Goldman et al (1986), Spigolon and Kelley (1984), and Bureau
of Reclamation (1974 and 1977). Even though Lutton (1986) is specifically
discussing construction of covers, much of his discussion is also appropriate
to soil liners.
The applicability and requirements for the various pieces of compaction
equipment that can be used to achieve desired compaction are presented in
Table 9-1. The adequacy, use, and efficiency of each piece of equipment
varies with numerous factors including type, weight and transmitted energy,
thickness of layers, placement water content, and material to be compacted.
The types of equipment in general use for gross compaction include
sheepsfoot rollers, rubber tired rollers, smooth wheeled rollers, crawler
tractors, and tampers. Vibrating baseplate rollers, power tampers (or
rammers) and manual tampers (or rammers) are used for fine finishing work
both in the base and sidewalls. Power tampers and manual tampers are
necessary for backfill compaction of trenches or where penetrations of
the base or sidewalls occur, e.g. around pipes, inflow/outflow/overflow
structures, and specialized supporting structures.
Compaction equipment can be selected based on weight and transmitted
energy requirements and the type of material to be compacted. For non-
cohesive materials used in constructing of granular drainage systems, com-
paction can be adequately achieved with track-type crawler tractor and/or
haulage units since light pressure and vibration is the most effective method
of compacting these materials. Frequently, complete drying and rewetting
is necessary to destroy the bulking effect of surface tension created by soil
moisture. Very firm compaction can be achieved on sands, gravels, and rock-
fill by the use of heavy vibratory wheeled compactors. Lifts of noncohesive
material up to 24 inches in thickness can be compacted with the vibratory
rollers. Generally, stones in the cohesionless material should be no larger
than 2/3 of the specified lift thickness (Coates and Yu, 1977). Drainage and
bedding requirements may result in the specification of materials much
smaller in size.
Heavy sheepsfoot rollers, pneumatic rollers, and vibratory compactors
are well suited for cohesive soil materials used in the construction of soil
liners. Figure 9-5 shows a sheepsfoot roller and a steel roller used in soil
compaction. Steel rollers are used particularly in final finishing of a soil
surface before liner placement. For compacting clays, rubber-tired rollers
are generally more successful than smooth steel rollers. When the clay
component of the composite liner is compacted with rubber-tired equip-
ment, the completed surface of a given lift will be smooth. Scarifying
the compacted layer with equipment such as a disk harrow is necessary to
9-7
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TABLE 9-1. COMPACTION EQUIPMENT AND METHODS
Requirements for compaction of 95 to 100 per cent Standard Proctor,
maximum^density
type IT ft coverages
thickness,
in. (cm
Sheepsfoot For fine-grained soils or
6 Soil type
rollers dirty coarse-grained (15)
soils with more than 20%
passing No. 200 mesh; not
suitable for clean
coarse-grained soils;
particularly appropr i ate
for compact i on of imper-
vious zone for earth dam
or 1 inings where bonding
of 1 1 f ts is important .
4-6 passes Fine-grained
for fine- so11 pl > 30
g r a i n ed Fine-grained
5011 : soil PI < 30
6-8 passes
g r a i n e d ^ ^ 1
<;ni 1
Foot
contact
area,
in 2 (Cm2)
5 - 12
(32 - 77)
7 - 14
(45 - 90)
10 - 14
(64 - 90)
Efficient compaction of wet
Foot
contact
pressures,
psi(MPa)
250 - 500
(17 - 34)
200 - 400
(1 4 - 2.8)
1 50 - 250
{1 0 - 1.7)
soils re-
Possible variations in equipment
For earth dam, highway, and
airfield work, drum of 60-m. dia.
(152 cm), loaded to 1 .5 - 3 tons
per lineal ft (43.7 - 87.5 kN per
lineal m) of drum generally is
used; for smaller projects, 40-in.
dia (101 cm) drum, loaded to 0.75
to 1.75 tons per lineal ft (21.9 -
43.7 kN per lineal m) of drum is
used; foot contact pressure should
be regulated so as to avoid
shearing the soil on the third or
fourth pass
quires less contact pressures than the
same soi1s at lower moisture contents.
rol lers
Smooth wheel
rol lers
Vibrating
baseplate
compactors
Crawler
tractor
Power
tamper or
rammer
soils with 4-8% passing
No. 200 mesh.
For fine-grained soils or
well graded, dirty
coarse-grained soils with
more than 8% passing No.
200 mesh.
Appropriate for subgrade
or base course compaction
of well -graded sand-
gravel mixtures.
May be used for fine-
grained soils other than
in earth dams, not
suitable for clean
well -graded sands or
s i 1 ty t"i i f nrm $ar-ds .
For coarse-grained soi Is
with less than about 12%
pass ing No . 200 Mesh ,
best suited for materials
wi th 4 - 8% passing No.
200 mesh, placed thor-
oughly wet .
Best suited for coarse-
grained soi Is with less
than 4-8% passing No.
200 mesh, placed thor-
oughly wet .
For difficult access,
trench backfill; suitable
for al 1 inorganic soi Is.
(25)
6-8
(15 - 20)
8 - 12
(20 - 30)
6-8
(15 - 20)
8 - 10
(20 - 25)
10 - 12
(25 - 30)
1-6 in (10
- 15 cm)
for silt
or clay; 6
in . (15
cm) for
coarse-
graded
soils
(0.41 - 0 55 MPa) for clean granular
material or base course and subgrade
compaction; wheel load 18,000 - 25,000 Ib
4-6 (80 - 111 kN), tire inflation pressures
in excess of 65 psi (0.45 MPa) for fine-
um form clean sands or si Ity f i ne sands ,
use large size tires with pressure of 40
to 50 psi (0.28 - 0 34 MPa).
4 Tandem type rol lers for base course or
subgrade compaction, 10 - 15 ton weight
(89 - 133 kN), 300 - 500 Ib per lineal
in. {3.4 - 5.6 kN lineal cm) of width of
real roller.
6 3- wheel roller for compaction of fine-
grained soil; weights from 5-6 tons (40
- 53 kN) for materials of low plasticity
to 10 tons (b9 krt) for materials of nign
plasticity.
3 Single pads or olates should weigh no
less than 200 Ib (0.89 kN); may be used
in tandem where working space is avai 1-
able, for clean coarse-grained soil,
vibration frequency should be no less
than 1,600 cycles per minute.
3-4 No smaller than D8 tractor with blade,
34,500 Ib (153 kN) weight, for high
compaction.
30 Ib (0.13 kN) minimum weight, consider-
able range is tolerable, depending on
materials and conditions
Wide variety of rubber tire
compaction equipment is available;
for cohesive soils, light-wheel
loads such as provided by wobble-
wheel equipment, may be substitut-
ed for heavy- wheel load if 1 1 f t
cohesionless soils, large-size
tires are desirable to avoid shear
and rutting .
3-wheel rollers obtainable in wide
range of sizes, 2- wheel tandem
rollers are available in the range
of 1 - 20 tons (8.9 - 178 kN)
weight, 3-axle tandem rollers are
generally used in the range of 10
to 20 tons (89 - 178 kN) weight;
very heavy rollers are used for
proof rolling of subgrade or base
course
Vibrating pads or plates are
available, hand-propel led or
self-propel led, single or in
gangs, with width of coverage from
3.5 - 15 ft (0.45 - 4.57 m ) ,
various types of vibrat ing-drum
equipment should be considered for
compaction in large areas.
Tractor weight up to 60,000 Ib.
Weights up to 250 Ib (1.11 kN);
foot diameter 4 to 10 in ( 1 57 -
3 93 cm).
Source: Coates and Yu, 1977, pp 90-91.
9-8
-------
Figure 9-5. Equipment for compaction and fine finishing. The top photograph
shnwc a <;hppn<;fr>nt rnllpr- thp hnttnm nhntnnranh <;hnw«; a stppl
shows a sheepsfoot roller;
roller for fine finishing.
the bottom photograph shows a steel
9-9
-------
ensure adhesion of the overlying layer. Figure
used to add water to soil prior to compaction.
9-6 shows a water vehicle
Figure 9-6. Water tank vehicle used to prepare the soil for compaction.
9.2.3 Construction of Embankments
The embankments are constructed in accordance with the design and with
sufficient stability and strength to prevent their failure. Most of the
operations carried on during the construction of the embankments are standard
to earthworks in general. Compaction, which is of particular importance in
constructing waste containment units, is discussed in the previous section.
Embankments can serve as the support for a soil liner placed on the interior
slope when the liner is placed in continuous lifts or part of the embankment
can incorporate the bottom liner soil component when the soil liner is placed
in horizontal lifts, as is shown in Figure 7-8. Thus, embankments can be
constructed either as homogeneous or zoned embankments (Figure 7-9).
Before constructing the embankments, the foundation needs to be in-
spected to ensure that it has adequate bearing capacity to support embankment
construction. Foundation soil analyses should include strength tests. The
materials to be used for constructing the embankments should be inspected
to ensure that all materials are uniform and as specified. If there is
concern about meeting the design requirements with the soil and the equipment
available, it may be desirable to construct a test fill, as is discussed in
the next section, to verify that the specified soil density/moisture content/
compactive effort/strength relationship developed by laboratory tests holds
for field construction conditions and to determine whether the construction
equipment is suitable. The inspection during construction is described in
more detail in Chapter 10. Drainage systems are installed and erosion
control measures are taken to ensure minimal erosion of the outer slopes of
the embankments.
9-10
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9.2.4 Construction of Soil Component of a Composite Liner
The soil liner used as the lower component of a composite liner serves
as a protective bedding material for the FML upper component and minimizes
the rate of leakage through any breaches that might occur in the FML upper
component. The basic requirements of the soil liner are that it should have
a maximum hydraulic conductivity of 1 x 10~7 cm s-1 and that it should serve
as a long-term structurally stable base for all overlying components of the
unit.
The soil material used in constructing the soil liner is selected after
being tested for hydraulic conductivity and compatibility with the waste
liquid or leachate to be contained. The soil should also have been tested in
a laboratory for density/moisture content/compactive effort/hydraulic con-
ductivity relations, particle-size distribution, Atterberg limits, and
other properties as required for the specific design.
The soil used in constructing a liner must first be excavated either
from a borrow source or from the site itself. If more than one soil is being
excavated from the same source, the different materials can be blended at the
excavation site. At the time of excavation, there may be a preliminary water
content adjustment, particularly if large amounts of water are required.
The soil is pulverized and stockpiled to allow it to hydrate before being
transported to the construction area. The surface on which the soil is
to be compacted is prepared by scarification with equipment such as a disk
narrow or special rakes with short teeth. Care is taken in controlling the
depth of penetration so that the integrity of previous compaction is ensured.
The soil is distributed over the construction area evenly and to the thick-
ness required so as not to exceed the thickness requirement for a compacted
lift. Measures are taken to break down the clods, and the moisture content
of the soil is adjusted so that the moisture content is within the required
range. Mixing and allowing the soil to hydrate after spraying with water may
be required to ensure that the soil has a uniform moisture content at the
time of compaction. Once compaction is finished, the soil is tested in
accordance with the QA/QC plan. If test results indicate the need, further
compaction is performed. Construction continues in lifts until the required
depth is reached.
In general, soil liners are compacted wet-of-optimum because of the
lower hydraulic conductivity values that tend to result from compacting
wet-of-optimum and because the higher moisture content will reduce the
tendency of a soil to form clods. The requirement for compacting wet-of-
optimum can pose construction problems if too much water gets into the soil,
e.g. by rainfall. Removing water from a clay soil is very costly and can
cause construction delays. The soil must be scarified and aerated in dry
weather.
Due to the nonhomogeneity of soil materials and the potential effects
of macrostructure deficiencies on the hydraulic conductivity of the in-place
9-11
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liner, the hydraulic conductivity and other criteria for field construction
that have been set as a result of laboratory testing may be difficult to
achieve by field compaction, as is discussed in Section 7.5.3.1.5. Con-
sequently, a test fill may be required using the same soil material, design
specifications, equipment, and procedures proposed for the full-scale liner.
An example of a test fill with a collection system is illustrated in Figure
9-7. Field hydraulic conductivity tests using an infiltrometer, such as the
sealed double-ring infiltrometer described by Daniel and Trautwein (1986),
can be performed. If field hydraulic conductivity testing of the in-place
liner is required for regulatory acceptance, other soils tests which can be
used as surrogate tests should be performed during construction so that the
results of measuring the field hydraulic conductivity of the test fill can
be used to estimate the field hydraulic conductivity of the full-scale liner,
as is discussed in Section 7.5.3.1.5 and in Northeim and Truesdale (1986).
Field variables (1986) that need to be carefully measured and controlled in
both the construction of the test fill and the full-scale liner include the
following Northeim and Truesdale (1986):
- Compaction equipment type, configuration, and weight.
- Number of passes of the compaction equipment.
- Method used to break down clods before compaction and the maximum
allowable clod size.
- Method used to control and adjust moisture content, including equili-
bration time, and the quantity of water to be used in any adjustment.
- The speed of the compaction equipment traveling over the liner.
Gravel to Load Clay
to Evaluate Effect of -> Sealed
Overburden Stress / \ Infiltrometer , Compacted Clay
Collection Pit
To Collection Pit
Collection Pan 1 FML l L— Underdrain
Lysimeter
Figure 9-7. Schematic of a test fill equipped to allow quantification of
hydraulic conductivity using a lysimeter and a sealed in-
filtrometer and to determine the effect of overburden stress
on the hydraulic conductivity of the compacted liner. (Source:
Northeim and Truesdale, 1986).
9-12
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- Uncompacted and compacted lift thicknesses.
- Methods used to tie the lifts together.
If different soil materials are being used to construct the liner, the test
fill can also be used to inspect the homogenization procedure.
Another important consideration is protecting the compacted soil liner
from climatic effects during and after construction. Rainfall can result in
erosion, in flooding of the site, or in over-moistening of the liner material.
Desiccation and freezing can result in cracking of the compacted liner. To
protect a site from the elements, inflatable domes have been installed over
the site so that construction can proceed during inclement weather (Goldman
et al, 1985). More frequently used measures include:
- Rolling the surface of the liner smooth with either a smooth drum or a
wheeled roller to protect the surface from erosion. The site needs to
be properly graded to ensure surface drainage to the lowest point of
the site and to prevent puddling or ponding on the liner surface.
Special measures may be required to remove water from the low point.
- Placing a plastic cover on the surface to prevent drying or wetting of
the liner.
- Placing a loose soil cover on the surface to prevent drying or erosion
of the liner.
- Placing a loose soil cover or a layer of organic mulch to protect the
liner from freezing. All organic material will need to be removed
before construction can continue.
- Spraying the soil surface with a soil sealant such as an asphalt
emulsion.
If cracks develop in the liner, it is necessary to blade down to unaffected
soil, disk the disturbed soil, and recompact.
Although much of experience has been accumulated in constructing similar
structures, e.g. dams, canals, embankments, etc., relatively little is known
about the construction of soil liners covering large areas; accordingly,
quality control inspection work is an important element of construction. The
effectiveness of the inspecting work will depend on the design of the quality
control program (i.e. test methods, sampling strategies, etc.), the ability
of the quality control team, its cooperation with the construction group,
and the capacity of the contractor to "learn while doing" and improve his
performance.
To assist in the inspection, there should be either an on-site labor-
atory or easy access to a qualified laboratory so that, at any time during
9-13
-------
the construction of the soil liner, a clear and quick qualitative assessment
can be made as to whether the work performed complies with specifications.
9.2.5 Fine Finishing of Soil Surfaces
After the compaction of the soil liner (which can serve as the bedding
layer for the FML) or other subgrade on which the FML is to be placed has
been completed, it is normal to fine finish the surface to avoid possible
puncture of the FML. Depending on the design specifications, various
techniques can be used. Often, teams of workers (generally from 2 to 10
depending on the size of the job) are assigned to scour the surface on both
the base and sidewalls, looking for and removing rocks or debris. Workers
are also encouraged to tamp down any soil which can be manually disaggregated
and spread.
Requirements for a smooth surface on the bottom and sidewalls has
resulted in drags being used to help form a regular, flat working surface.
Usually, the fine finishing with vibrating rollers and drags will need to be
performed on a slightly wet surface. Fine finishing with a smooth steel
roller is sometimes required. Occasionally, in constructing the foundations
for a nonhazardous waste containment unit, soil additions are required to
bridge surface irregularities if the irregularities cannot otherwise be
removed.
Figure 9-8 shows examples of subgrade that require additional work
before an FML can be placed; Figure 9-9 shows scraper and roller being used
to fine finish a subgrade, and Figure 9-10 presents examples of a suitable
subgrade texture prior to placing an FML.
Vegetation at the site may need to be controlled to prevent damage to
the FML, particularly if the FML is left uncovered or the unit is left
unfilled for a while. In cases where the FML is to be installed directly on
a foundation (i.e. in a containment unit for nonhazardous materials), un-
wanted grasses and other types of vegetation are controlled in the fine-
finishing stage by removing of the layer containing the vegetation and/or
applying a herbicide to the finished slopes and base. Selecting a proper
herbicide is critical as some species of grasses found in western states are
not killed by certain herbicides commonly used in the more humid eastern
United States. In addition, application of the herbicide should not pose a
long-term danger to human health and environment and should not interfere
with the groundwater monitoring program for the facility. All fill obtained
off-site should be inspected well to ensure that both germinating and in-
active seeds and roots are killed by the application of herbicide.
Generally, if herbicide is applied, there is a delay of a few days
before the FML installation begins so the herbicide is absorbed by the soil
and so components that may react with the FML are allowed to volatilize.
Figure 9-11 shows what can happen if an herbicide is not applied properly.
The picture shows salt grass penetrating a 30-mil FML. When applying
herbicides, proper protection against inhalation and skin contact should be
taken.
9-14
-------
-, • < ,—*t,r - ;>v,"*.'"9
• ,,* •-, ,•'•*, "'-• s *•>
^ "?¥.:*
%* ,* V
Figure 9-8. Photographs showing various stages of subgrade finishing.
subgrades require further work.
9-15
These
-------
Figure 9-9. Scraper and roller being used to fine finish a subgrade.
Figure 9-10. Representative subgrade surface texture prior to placement of
an FML.
9-16
-------
Figure 9-11.
Salt grass penetrating a 30-mil FML. Soil
important prior to placing an FML liner.
sterilization is
The activities of excavation, construction, trenching, compaction, fine
finishing, and liner installation are generally all progressing at the same
time on larger jobs. It may be desirable during dry weather to sprinkle
water or other dust control compounds on the prepared soil surface since
seaming FMLs is best performed in a dust-free environment.
9.3 INSTALLATION OF FMLS
Installing
construction.
an FML requires a significant amount of planning prior to
This planning must consider the storage and security of
all necessary equipment, installation equipment, manpower requirements, the
placement operation, field seaming, anchoring and sealing, construction
quality control (CQC), construction quality assurance (CQA) inspection, and
protection of placed liners. These considerations are discussed in detail
in this section.
9.3.1 On-site Storage of Materials and Equipment
Items requiring storage will include the FMLs and all equipment neces-
sary for installation. Figure 9-12 shows FMLs packaged and shipped to the
site. Depending on the type, FMLs are packaged in folded panels or rolls
which can weigh from 2,000 to 10,000 pounds each. All FMLs should be stored
out of sunlight if possible to prevent degradation and, depending on the FML
type, to minimize blocking, a phenomenon that occurs when an FML sticks to
itself during shipping or storage, resulting in delamination or ripping when
unrolled onto the subgrade. Figure 9-13 shows the result of blocking of a
9-17
-------
„'•»,«»- ***'»•
Figure 9-12.
FML panels are shipped to
rolled or accordion-folded.
the site on
wooden pallets either
9-18
-------
reinforced FML, with the scrim exposed. This damage must be repaired. FMLs
are shipped rolled or accordion-folded in cardboard boxes and placed on
wooden pallets. The FML can thus be moved from the storage site to the
construction site by means of a fork-lift truck, or some other suitable piece
of equipment, without damage.
Figure 9-13.
Damage to a fabric-reinforced FML caused by "blocking" of the
sheeting. Blocking can occur during shipping or storage when
the FML is rolled or folded and sticks together under warm
conditions. The exposed fabric reinforcement must be repaired.
An important consideration in storing equipment and
preventing of vandalism and theft. A temporary fence can
FML can be stored in an existing secured area.
FMLs at a site is
be erected, or the
The need for an elaborate storage system can be minimized if the job is
planned so that all equipment and materials necessary arrive at the site at
the same time, and installation begins immediately, after their arrival.
9.3.2 Equipment and Materials for Installing FMLs
The equipment needed to install an FML varies with depends the type of
FML to be installed and the complexity of the job, which depends on factors
such as size of the site, side slope steepness, the number of penetrations,
the number of seals required, and the length of installation time anti-
cipated.
9-19
-------
The major types of equipment and materials needed for installing FMLs
include:
- Equipment for transporting the FMLs to and on the construction site
and for use in unrolling or unfolding the FML panels or rolls.
- Equipment and materials for holding the FML in position after it has
been spotted.
_ Equipment and materials necessary for seaming the FML.
- Equipment and materials for the safety of the work crew.
Some means of moving the FML from the storage area to the construction
site and on the construction site is necessary. A forklift truck for moving
FMLs placed on pallets can be used,-though other pieces of equipment, such
as a backhoe or front-end loader, can also be used. HOPE FMLs, which are
brought to the site in rolls rather than on pallets, require a crane or
front-end loader for moving to the construction site. These rolls can weigh
up to 10,000 pounds, and special straps are used in moving them (Figure
9-14).
A backhoe may prove useful if touch-up work on subgrade preparation
is required during installation. A backhoe or front-end loader can also be
used to move sand to the top of the slopes so that sand bags can be filled
to prevent the wind from damaging panels or rolls that are about to be
seamed.
Once the panels or sheets have been laid out, an FML often needs to be
moved across the subgrade by field crews. Wooden dowel rods can be used to
help move panels without stretching the edges which will be seamed. These
dowel rods are placed on the edge of the panel; the panel is then rolled onto
the dowel rod. This provides a handle so that the panels can be moved with-
out stretching and tearing the FML.
To control the effects of wind on FML panels or rolls that have been
laid out, sandbags can be placed every 5 to 10 ft along unseamed edges.
Figure 9-15 shows sandbags being used to prevent wind damage to an FML.
Old tires have also been used. However, discarded steel-belted radials may
have exposed wires that could damage the FML.
The type of equipment needed for seaming the FML will depend on the
method by which the FML is seamed. The majority of FMLs are seamed in the
field with either solvent-based or thermal-based techniques. Techniques for
seaming FMLs are discussed in Section 4.2.2.3.
PE FMLs are heat-welded and require specialized equipment, some of which
are proprietary and are used with a particular manufacturer's FML. Such
equipment includes extrusion welders that can be raised or lowered along the
sidewalls of the unit and others that can be hand-held. Figure 9-16 shows
9-20
-------
Figure 9-14. HOPE FMLs are shipped to the site rolled onto drums. Each roll
may weigh up to five tons.
9-21
-------
Figure 9-15.
Use of sandbags to anchor unseamed sheets and unseamed edges of
FMLs to prevent wind damage.
-------
Figure 9-16.
Hand-held extrusion welders for seaming HOPE FMLs. A fillet of
molten HOPE is extruded over the edge of the overlap. (Top
photo: courtesy of Gundle Lining Systems; bottom photo:
courtesy of SLT North America, Inc.).
9-23 •
-------
two hand-held extrusion welders, Figure 9-17 shows a partially-automated
extrusion welder being lowered down a side slope by a winch, and Figure 9-18
presents a schematic of a hot-wedge welding device used in seaming PE FMLs.
Figure 9-17.
A partially-automated extrusion welder for seaming HOPE FMLs.
Molten HOPE is extruded between the overlap of the two sheets
being seamed. The welder is shown being lowered down a side
slope by a winch.
FMLs seamed in the field with adhesives or by solvent-based techniques
use hand rollers to ensure good contact between the surfaces being bonded.
In addition, a board at least 1 in. thick, 12 in. wide, and up to 12 ft long
should be available for each seaming crew to use. This board provides sup-
port during seaming and is placed under the overlap of the
As seaming progresses,
a good seaming
so that they can
».._u. v..^- w , _. . „ ~ v , „,._ liner
the board is slid along underneath the seam to provide
surface. These boards normally have ropes tied to the front
be pulled along underneath the seam as the seaming crew
moves from the middle of a panel to the ends. Figure 9-19 shows the rope
attached to a seaming board placed underneath the seam.
Many FMLs require surface cleaning or treatment in the seaming area just
prior to actual seaming. A sufficient supply of clean cotton rags needs to
be available for wiping away moisture or dust and debris. Appropriate clean-
ing solvents may also be required. For seaming CSPE FMLs, means of scouring
the FML surface, such as natural brushes or stainless steel scouring pads,
may be needed to remove surface cure prior to seaming, particularly if the
FML is installed too long after its manufacture.
9-24
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Squeeze Roller
3 -— FMLs
Hot Wedge
Direction of Seaming
Figure 9-18. Schematic of hot-wedge welding device for seaming PE FMLs,
[Based on U.S. Patent 4,146,419 (March 27, 1979)].
Figure 9-19.
Field seaming operation using bodied-solvent adhesive. A board
is being used for support under the area being seamed; the
board is pulled along under the seam with the rope shown in the
picture.
9-25
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Heat guns should be available for solvent seaming operations. These
guns can bring the FML to a suitable temperature if the ambient temperature
is below 60°F. Figure 9-20 shows heat guns being used to warm an FML. If
trichloroethylene is used in seaming, heat guns should be used with extreme
caution, as toxic phosgene gas can be formed.
Additional equipment needed for installing FMLs can include caulking
compounds and caulking guns, pails for washing solvents, paint brushes or
other applicators, solvent resistant gloves, safety goggles for men working
with solvents, knee pads, shoes with flat soles to prevent damage to tte
FML, scissors and a utility knife, hand-held earth tampers, hand rakes,
shovels, and stakes and string to help in the spotting of the panels or
rolls. Respirators are often needed, especially when solvent and solvent
based adhesives are used and the work is performed in confined areas. If
electrical equipment is being used during installation (e.g. heat guns and
extrusion welding equipment), an electric generator and sufficient extension
cords are necessary. A crayon should be available for marking the location
of seams before solvents are applied and for use in identifying samples for
QA/QC testing. Some methods of seaming HOPE require buffing of the edges to
be seamed together. In this case, the proper buffing equipment is required.
A list of the equipment and materials often required for installing
FMLs is presented in Table 9-2. Equipment used to test field seams is
discussed in more detail in Section 9.3.6.
9.3.3 Manpower Requirements for Installing an FML
Installation of an FML requires a qualified contractor who has adequate
experience with installing FMLs, particularly with the generic type of FML
being installed. Some FML manufacturers have suggested that 1 million square
feet of experience of adequately installed liner should be a requirement for
being considered a qualified contractor. The installation contractor should
plan and implement a quality control program which will help ensure that the
FML meets material specifications and is installed in accordance with con-
struction specifications. At the same time, the owner or his representative
should plan and implement a quality assurance program. Inspection needs to
be documented for review and record keeping.
The manpower requirements for installing FMLs are a function of the rate
at which the installer wants to place panels and accomplish field seaming.
Typically, installation contractors will have from five to ten people on site
when placing one panel at a time. Generally, a crew foreman will direct the
activities of the field crew. The foreman may not directly participate in
the unrolling and spotting of panels or in field seaming; however, he must be
experienced in installing the specific FML.
Crew size requirements also depend on the complexity of the installation
and the experience of the field crew. If the majority of the crew members
are recruited locally, they probably will require training during instal-
lation. At the present time, the trend is toward having installation con-
tractors retain field supervisors who travel from job site to job site.
9-26
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Figure
9.20. Heat guns being used to fad
9-27
Ilitate field seaming of FMLs,
-------
TABLE 9-2. EQUIPMENT AND MATERIALS FOR INSTALLING FMLS
Item
Use
Fork lift or other lifting equipment
Sandbags
Proper adhesives
Portable electric generator
Seaming equipment
Equipment for testing seams:
- Ai r-1ance
- Vacuum box
- Ultrasonic devices
- Spark tester
- Field tensometer
Hand-held earth tampers
Miscellaneous materials:
- Adhesive applicators (paint
brushes, caulking guns, rollers,
etc.).
- FML preparation equipment:
clean rags, scrub brushes,
scouring pads, pails for solvent,
hard surface rollers, seaming
support board, heat guns, crayons
for marking, dowels for pulling
panels, stakes and chalk line,
steel measuring tape, scissors
and utility knives, electrical
extension cords (for heat guns).
Field crew equipment:
- Safety goggles, solvent resistant
gloves, knee pads, respirators,
soft-soled shoes.
First aid kit
Ai r compressor
To move and aid in the placement of
FML panels and rolls.
To anchor temporarily unseamed panels
or rolls to prevent wind damage.
To make field seams and seal FML
around concrete or steel penetrations.
To operate heat guns or lighting for
working at night.
To seam the panels or sheets of FML.
For QC testing of field seams.
To test the continuity of field seams.
To test the continuity of field seams.
To test the continuity of field seams.
To test the continuity of field seams.
To test the strength of field seam
samples.
To smooth subgrade as necessary.
For field seaming.
For field crew when making seams.
In case of accidents.
Supply air that might be needed when
working with solvents, and for air-
lance.
9-28
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Large jobs where crews perform specific tasks may involve many people. This
occurs where one crew unrolls panels, another crew spots the panels, and a
third crew performs all field seaming. Crew sizes also depend on the number
of structures or penetrations in the unit. For example, if three or four
concrete pillars are located within the area of one panel or roll, this
situation will require more manpower than if the FML is to be placed on a
flat surface. In many instances, the owner of the unit may provide necessary
manpower on an as-needed basis to the installation contractor. This arrange-
ment will minimize the direct cost of installation to the owner, as excess
work loads can be fulfilled with temporary labor.
9.3.4 Placement of an FML
An FML should be installed during dry, moderately warm weather. Instal-
lation during extremely cold, extremely hot, and/or wet weather can also be
performed if it can be demonstrated that adverse weather conditions do not
affect the integrity of the installed liner; a more rigid program for in-
specting construction performed under adverse conditions should be formu-
lated. Before the FML is moved from the storage site to the installation
location, a number of tasks need to be performed, including:
- The anchor trench around the perimeter of the installation should be
completed. The dirt excavated from the anchor trench should be raked
smooth so that the FML can be unrolled along and parallel to the
anchor trench in the width direction.
- The surface of soil subgrade should be inspected to make sure that it
is firm, flat, and free of sharp rocks or debris. If inspection of
the soil surface indicates the need for further fine finishing, this
work should be performed as required.
- If standing water is present in the unit, it should be removed.
- Concrete structures that must be seamed around should be inspected to
ensure that there are no sharp edges and that systems for anchoring
the FML are prepared. If skirts are to be used around footings on
concrete structures, these should be inspected to ensure that they are
in place.
- All outflow or inflow structures or other appurtenances required by
the designer should be inspected to ensure that they are in place.
Before placing the FML, the layout is consulted, and the rolls or folded
panels are placed in the appropriate place indicated on the sheet layout,
which will also indicate the direction in which the FML should be unrolled or
unfolded. Instructions on boxes containing folded/rolled FML panels indicate
the directions for unrolling and unfolding the FML so that it can be placed
correctly (Figure 9-21). The FML is unrolled or unfolded lengthwise, as is
shown in Figure 9-22. Depending on the FML type, it is then unfolded in the
width direction, either down the side slope or across the floor (Figure
9-23). The field crew then begins to position or "spot" the FML into its
proper location so that a sufficient overlap of adjacent panels or rolls is
maintained for seaming (Figure 9-24). Generally, panels and rolls are placed
9-29
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Figure 9-21. The instructions for unrolling FML panels are
clearly shown on each container.
9-30
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Figure 9-22. Panels of a fabric-reinforced FML being
unfolded or unrolled.
9-31
-------
Figure 9-23.
Workmen "pulling" a panel fabricated from a
FML across the subgrade. This step can be
complish during windy conditions.
fabric-reinforced
difficult to ac-
9-32
-------
Figure 9-24.
Spotting a panel fabricated from
an FML panel has been unfolded,
it in the proper location.
a fabric-reinforced FML. Once
the crew "spots" or positions
9-33
-------
so that field seams will run perpendicular to the toe of the slopes; that is,
the seams will run up and down rather than along the side slopes. This
practice minimizes stress on field seams in the short run, while they are
setting or curing and in the long run, while the FML is in service. As
sheets or panels are spotted and seamed together, sand bags are placed on top
of the FML, as is shown in Figure 9-15. The FML should be pulled relatively
smooth over the subgrade (Figure 9-25). If the subgrade is smooth and
compacted, then the FML should be relatively flat on the subgrade. However,
sufficient slack must be left in the FML to accommodate possible shrinkage
due to temperature changes which may result in tension in the FML.
Figure 9-25.
Pulling an FML panel smooth. Each FML panel must be pulled
smooth, leaving enough slack to accommodate anticipated
changes in dimensions due to temperature changes.
It is important to make sure that no "bridging" occurs in the FML where
angles are formed by the subgrade directly under an FML. Bridging is the
condition that exists when the FML extends from one side of an angle to the
other, leaving a void beneath the FML at the apex of the angle. Bridging
occurs most often at penetrations and where steep sidewalls meet the bottom
of the unit. Particular attention has to be directed to keeping the FML in
contact with the subgrade at these locations and keeping it in a relaxed
condition. It is also important to be sure that compaction of the subgrade
in these areas meets design specifications to avoid localized stressing of
the FML or the seams.
Depending on the location and the weather conditions, the number of
panels or rolls placed in one day should not exceed the number which can be
seamed in one day. This assures that, should bad weather conditions occur
9-34
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overnight, the FML will not be left unseamed and subject to damage, especial-
ly from wind.
9.3.5 Field Seaming of FMLs
The success or failure of an FML installation depends to a great ex-
tent on both short-term and long-term integrity of all seams. Field seaming,
which is performed under conditions that cannot be completely controlled, is
a critical factor in FML installation. FML manufacturers recommend pro-
cedures and seaming systems for achieving successful field seams. If the
manufacturer does not have a recommended seaming system, then the use of that
FML should be questioned. During installation, the contractor should follow
the manufacturer's recommended procedures for seaming and anchoring the FML
to structures, etc., except in cases where it has been demonstrated that the
procedure, technique, or equipment proposed by the installer results in seams
of equal or higher quality.
FMLs are usually seamed in the field using either solvent-based or
thermal-based techniques; the specific technique used during installation
will depend on the FML type. Crossl inked FMLs, such as EPDM and neoprene
FMLs, are usually sealed using gum tape and a two-part adhesive system. The
reason for the general tendency in recent years to avoid using crosslinked
FMLs is that there are many difficulties associated with forming a good bond
between sheets of crosslinked FMLs. Uncured or unvulcanized FMLs, such as
CSPE, CPE, and PVC FMLs, are usually sealed with solvents, bodied-solvent
adhesives, or heat. Polyethylenes are sealed by various thermal methods,
e.g. hot-air, hot-wedge, ultrasonic, or by one of several fusion extrusion
methods. Using of methods of joining FMLs that ensure molecular movement
across the interface of the sheets and using FMLs containing no processing
aid lubricants, such as those used to aid in extrusion, or other additives
that may have exuded or "bloomed" to the surface of the sheets being joined
help ensure good seam strength and durability. Methods of seaming FMLs are
discussed in Section 4.2.2.3.
The long-term integrity of the field seam is determined by many factors.
The most important factor is that the bonding system used must join the two
FML surfaces on a molecular level under actual field conditions. It should be
noted that differences between seaming equipment exist and that some equip-
ment may be more appropriate for use under a wider range of conditions. The
four basic conditions required for producing durable seams by thermal methods
are cleanliness of the bonding surfaces, sufficient heat, sufficient pres-
sure, and "dwell" time. In the case of an adhesive system, the basic re-
quirements are the same except that the adhesive takes 'the place of the heat.
Sufficient pressure and dwell time are necessary to create permanent bonding
of the seam interface.
At present, most seaming techniques are manually controlled, i.e. they
are not automated. Therefore, the success of a seaming operation for a given
FML can be influenced by many job site factors including:
- The ambient temperature at which the seams are produced.
9-35
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- The relative humidity.
- The amount of wind.
- The effect that clouds have on the liner temperature.
- The moisture content of the subgrade underneath the FML.
- The supporting surface on which the seam is bonded.
- The skill of the seaming crew.
- The quality and consistency of the adhesive, if an adhesive is used.
- Proper preparation of the FML surfaces to be joined.
- Sufficient overlap of adjacent panels or rolls to be seamed.
- The cleanliness of the seam interface, i.e. the amount of airborne
dust and debris present.
- The ease in handling the seaming equipment.
Field seaming of FMLs during adverse weather conditions requires special
considerations regarding the potential effect of these conditions on the
particular bonding system. The adhesive system or specialized equipment used
or recommended by the manufacturer or installer to seam the FML being in-
stalled can be affected by adverse weather. Cold weather seaming requires
the field crew to exercise caution when making seams to make sure that the
FML reaches a minimum temperature. Most solvent-based systems work best at
ambient temperatures greater than 50°F. Temperature and wind velocity affect
the rate at which solvents evaporate and thus the ability of the solvent-
based adhesive to develop a sound bond between the sheets. Usually mixtures
of solvents are used, the proportions of which can be varied in order to
control evaporation rates at different temperatures. When the ambient
temperature is below 50°F, the relative humidity is high, and a solvent-based
system is being used, moisture condensation can take place due to the cooling
effect of evaporation. Under such circumstances heat guns can be used to
raise the temperature of the FML. However, extreme caution must be exercised
when using heat guns around flammable solvents and chlorinated solvents which
may generate the toxic gas, phosgene. For the same reasons, smoking should
not be allowed on the job. Solvent seaming at high ambient temperatures can
pose problems due to the volatility of the solvent which may not sufficiently
dissolve the surfaces to be seamed before it evaporates. High ambient
temperatures can also limit the ability of crews to work. Thermal and fusion
systems for seaming HOPE FMLs have reportedly been used at temperatures as
low as 25°F. External heat may need to be used to raise the FML temperature
as required. Field seaming during precipitation should be avoided. A more
rigid QA/QC program for inspecting seaming performed under adverse weather
conditions needs to be formulated and implemented.
9-36
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The method of applying pressure to the seam will vary with the type
of seaming operation. Some thermal-based equipment for seaming FMLs have
squeeze-rollers for pressing the two sheets together immediately after
heating (Figure 9-18). FMLs seamed using solvent-based techniques need to be
pressed together using hand rollers. Because these FML are usually fairly
pliable, the seam needs to rest on a dry, hard, flat surface for rolling.
Many installers use a board placed underneath the seaming area, as is
described in Section 9.3.2. The boards are pulled along underneath the seam
as the seaming operation progresses.
Seam overlap requirements vary with FML manufacturer, FML type, and
seaming procedure. Recommended overlaps vary from 4 to 12 inches. Figure
9-26 illustrates typical factory and field seams for fabric-reinforced
thermoplastic FMLs. Figure 4-12 schematically presents various configu-
rations of FML seams. Overlap requirements for fabric-reinforced FMLs
are often stated as a minimum bonded overlap of the reinforcing fabric.
Figure 9-27 shows the overlap between panels being inspected.
The surfaces to be bonded need to be properly prepared, i.e. clean
and dry, when the field seams are made. The presence of any moisture can
interfere with bonding of the FML surfaces. The presence of any dirt or
foreign material can jeopardize the seam integrity and provide a path for
fluid to migrate through the seam. In the case of FMLs being seamed with an
adhesive or a solvent, once the board is placed underneath the FML and the
overlap is sufficient, then the top FML is peeled back and the surface
prepared for the adhesive or solvent (Figure 9-28). In some installations, a
solvent that will not inhibit bonding between the two surfaces can be used to
clean the FML. In the case of some FMLs, e.g. aged CSPE, a cured or oxidized
surface layer needs to be removed by careful buffing followed by a solvent
wash prior to seaming. Field crews should wear suitable gloves to prevent
skin irritation from the solvents (Figure 9-29). Respirators and eye pro-
tection may also be required. Once the surface has been cleaned with
solvent, the adhesive is applied to the FML. Care needs to be taken to apply
the adhesive uniformly. Figure 9-30 shows the application of adhesive with a
squeeze bottle and with a paint brush. Generally, with a bodied solvent
adhesive, the two surfaces should be placed together immediately (i.e. before
the adhesive begins to "skin") and rolled with a steel or plastic roller
(Figure 9-31). Initial rolling is performed perpendicular to the edge of the
panel to ensure spreading of the adhesive across the width of the seam.
Some methods of seaming HOPE FMLs require buffing of the surfaces to be
seamed together in order to present a fresh surface for bonding by removing a
layer of oxidized material and compound additives that may have exuded to the
surface of the sheeting. Surfaces can be buffed either parallel or perpen-
dicular to the seam edge, as is shown in Figure 9-32. Some concern has been
expressed over the possibility that parallel buffing may have a higher
potential for initiating stress cracking in the field and causing loss of
tensile strength. Therefore, even though buffing parallel to the seam is
easier and quicker for the installer, perpendicular buffing is considered
technically better. Care needs to be taken in all buffing operations to buff
only those areas required for seaming and to prevent the grinder from digging
too deep.
9-37
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to 1" SELVAGE EDGE
IN.
~ FLEXIBLE MEMBRANE LINER
(a) Factory Seam
1/4" to 1" SELVAGE EDGE
BODIED SOLVENT-
ADHESIVE
i1
4" to 12"
h
p""
FLEXIBLE MEMBRANE LINER
(b) Field Seam
Figure 9-26. Typical lap seams for fabric-reinforced thermoplastic FMLs
(Source: Small, 1980).
The crew should be careful not to allow any wrinkles to occur in the
seam (Figure 9-33). Sheets should lie flat during seaming, with their sur-
faces contacting each other. Wrinkles can result in "fish mouths" which must
be cut out and repaired. The sheets being joined need to be allowed to
equilibrate to the same temperature and to flatten after being placed.
Some sheets or panels may need some pulling to smooth them out; however,
pulling the sheets smooth should not introduce stresses into the sheeting.
Some installers of PE FMLs have found that seaming during cool weather or
during cool parts of the day can greatly reduce the number and magnitude of
problems (e.g. wrinkles or uneven shrinkage) caused by thermal expansion and
contraction. Field seaming using solvent-based techniques normally begins at
the center of a panel and continues to each end to minimize formation of
large wrinkles which can occur if seaming begins at one end or the other.
If an electric generator is required during installation (e.g. for heat
guns, seaming equipment, etc.), care needs to be taken to ensure that hot
parts do not contact the FML and that gasoline does not spill onto the FML
during refueling.
9-38
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Figure 9-27. Inspecting overlap between panels of a fabric- rui iforced FML.
Sufficient seam overlap must be maintained. Manufacturers
usually specriy minimum overlap for field seams.
9-39
-------
Figure 9-28.
Cleaning the surface of a fabric-reinforced FML prior to
seaming. The surfaces to be seamed must be cleaned to remove
dirt. A solvent that will not inhibit bonding can be used to
clean the FML surface.
9-40
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Figure 9-29.
Seaming crews working with solvents are advised
to wear gloves for protection.
9.3.6 Field Testing of Seams
The quality of the seams made during installation is critical to the
success of an FML-lined waste containment unit. Considering the great length
of seams that may be made during the field installation of an FML liner for a
single unit, and considering the variable and uncontrolled conditions that
can exist during the seaming operations, it is essential to monitor the
quality of the seams. The seams should be inspected and tested to determine
whether they are continuous, i.e. whether there are gaps in the seams.
One-hundred percent nondestructive testing of the seams is necessary as part
of the quality control that must be performed by the installer. The seams
should be first visually inspected and afterwards tested by one or more
nondestructive techniques that are more objective. Table 9-3 lists and
and describes a series of nondestructive-type tests that might be performed
on the seams. This table also indicates, some of the limitations of the
respective methods. The tests include the vacuum-box method, air-pressure
method, ultrasonic tests, spark tests, air-lance tests, and a probe tech-
nique. Equipment for two of these methods used to assess the continuity of
HOPE FML seams are shown in Figure 9-34. The ultrasonic shadow method is
discussed further by Koerner et al (1987). However, none of the nondestruc-
tive test methods measure the strength of any given seam, nor the long-term
chemical durability of that seam. At best, these test methods can only
determine continuity of a seam.
9-41
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Figure 9-30.
Field seaming of a fabric-reinforced thermoplastic FML using a
solvent-based technique. The bodied-solvent adhesive is
applied using either a squeeze bottle or a paint brush.
9-42
-------
Figure 9-31.
Rolling the seam of a fabric-reinforced thermoplastic FML.
After the proper adhesive has been applied, the seam is rolled
smooth.
Destructive tests, in which samples of the seams are cut and tested in
shear and in peel, measure the strength of specimens of the seams. This
testing, described in Chapter 4, is performed by both the installing con-
tractor and the construction quality assurance organization. The validity
of this testing depends to a large extent upon the sampling strategy and
procedure that is followed. Destructive testing and its use in quality
control and quality assurance of seams is discussed in Chapters 4 and 10,
respectively.
9.3.7 Placement of a Protective Soil Cover on an FML
If a protective soil cover has been specified in the design to protect
an FML from weather conditions, equipment, and vandalism, it is placed as
soon as scheduling permits. Generally, the FML is not covered until FML
9-43
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installation
portions of
entire liner
is complete and has been accepted. However, on large projects,
the liner may be installed, accepted, and covered before the
is installed.
Buffing Marks
HOPE FML
(a) BUFFING PARALLEL TO THE SEAM EDGE
Buffing Marks
HOPE FML
(b) BUFFING PERPENDICULAR TO THE SEAM EDGE
Figure 9-32.
Parallel and perpendicular buffing of an HOPE FML. These marks
should extend as little as possible outside the seam area.
During construction of the soil cover, particular care is taken to
prevent damage to the FML. The cover soil should never be pushed down the
slopes since the gravitational stresses may cause the FML to come out of the
anchor trench or cause the liner to tear. Instead, once a ramp is built,
placement of the cover usually proceeds from one end of the project to the
other with soil being pushed up the slopes. Some FML manufacturers recom-
mend that no bulldozer larger than a D-3 with wide tracks should be allowed
for working around lining projects. Care needs to taken to prevent operator
error from damaging the FML (or underlying drainage layers). Operator errors
can include allowing a dozer blade or the bucket of a front-end loader to go
too low or allowing dozer tracks to spin. In addition, as placement of a
soil cover progresses, care needs to be taken to prevent wrinkles from
developing at the leading edge of the soil. Wrinkles can be trapped by
depositing soil on the opposite side of the wrinkle using the bucket of a
9-44
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Figure 9-33. Repairing a wrinkle in the seam of a fabric-reinforced thermo-
plastic FML. Wrinkles are also known as "fish mouths". The
wrinkle is first preheated with a heat gun (top); after apply-
ing adhesive, the wrinkle is folded; the wrinkle has been
rolled smooth and washed with a solvent; a patch is applied as
a final step (bottom). Thicker sheeting, e.g. 45-mil, and
stiffen sheeting, e.g. HOPE, may require slitting and use of a
cover strip.
9-45
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TABLE 9-3. NONDESTRUCTIVE TESTS USED TO EVALUATE SEAM CONTINUITY
Test
Description
Applicability
Comments
Vacuum box
Ai r pressure
Ultrasonic
Spark testing
Ai r-1ance
A soapy solution is applied to the
FML. A box with a transparent
window is sealed against the
FML and vacuum is established
in the box. Soap bubbles will
form if there is a leak.
Mostly for stiff FMLs.
A double seam with intermediate
open channel is made. Pres-
surized air is blown into the
channel. Leakage is detected
if the air pressure cannot be
kept constant.
Any type of FML if
seamed with double
seam with inter-
mediate channel
Underseam may fail,
in which case seam
may require capping.
Several types of ultrasonic tech-
niques are used to assess the con-
tinuity of a seam: (1), the mea-
sured thickness of the seam can
be compared to the thickness it
should have; and/or (2), voids
in the seam can be detected
directly.
A conducting wire is placed in
seam during seaming. A spark
can be established between the
wire and an electric device
if the wire is exposed, i.e. if
a portion of seam is missing.
A pipe with a nozzle is used
to blow pressurized air at
the edge of a seam. If there
is a lack of continuity in the
seam air flows under the FML
and inflates it or causes it
to vibrate, often audibly.
FMLs which may be
fused.
All FMLs, but requires
conducting wire in-
serted in seams.
Mostly for pliable
FMLs.
Most commonly used test with
stiff FMLs, such as HOPE,
whose thickness exceeds
0.75 mm (30 mil).
Cannot be used in corners or
around small radii without
special apparatus.
Relatively slow process
since testing area is
limited by size of vacuum
box.
Used only with double seams
with intermediate open chan-
nel, i.e. seams made with
double-hot-wedge or double-
hot-air.
More severe loading than
vacuum test, but tests
only a small fraction of
seam strength.
Causes some damage to
FML because "leading
hole" must be cut.
Quite efficient method
since long sections of
seam (up to 100 m) may
be tested at one time.
When defects are found,
a vacuum box is often
used to locate the
defect.
Reliable test when con-
ducted by very experienced
operator over small areas.
Difficult to interpret
readout over long periods
of time due to operator
fatigue.
Difficult to set up ac-
curately over large areas.
Applicable in areas where
vacuum cannot be used
(corners, etc.).
Results not always reli-
able.
Qualitative test only.
Results not very repro-
ducible.
Probe
A stiff probe, such as a
blunt screwdriver, is used
to verify mechanically if
the seam is continuous.
All FMLs and all
seams with well-
defined edge.
Qualitative test only.
Results not very repro-
ducible.
Source: Based on Giroud and Fluet, 1986, pp 272-273.
9-46
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Figure 9-34.
Testing the continuity of HOPE FML seams. The upper phi
(courtesy of Gundle Lining Systems) shows the use of a
box" and the lower photograph (courtesy of Schlegel
Torhnninnw^ shows t.hp use of an ultrasonic technique.
DOX C1MU L I Id IUVKCI JJ n w U
Technology) shows the use of an
9-47
"vacuum
Lining
-------
wheel loader (Yamamoto, 1987). Once trapped, soil can be placed on top of
the wrinkle. This method of trapping the soil prevents the wrinkle from
folding over on itself. As the placement proceeds up the slopes, the leading
edge can be wrapped with geotextile at the end of each day to minimize the
effects of wind and rain.
9.4 CONSTRUCTION OF LEACHATE COLLECTION. AND REMOVAL SYSTEMS (LCRSs)
In a waste containment unit there can be one or more LCRS. In a hazard-
ous waste landfill there can be two systems: a primary LCRS above the top
liner, which drains the leachate that may be generated within the waste being
contained, and a secondary LCRS between the top and bottom liners which
collects the leachate that might flow through a breach in the top liner. The
latter system functions as a leak-detection system. In a hazardous waste
surface impoundment there is only the secondary leachate collection and
removal system or leak detection system to detect and collect liquid that may
flow through a breach in the top liner. The number of LCRSs in nonhazardous
units will depend on the type of unit, the design requirements, and regula-
tory requirements.
An LCRS typically is comprised of a number of subcomponents including:
- A drainage layer consisting of either granular or synthetic drainage
media.
- A filter system to prevent clogging of the drainage layer and/or the
pipe.col lection network.
- A strategically-placed network of perforated pipe for transporting
leachate or a waste liquid from the drainage layer to the sump/manhole
system.
- A bedding layer for the pipe network.
- A sump/manhole system which allows collection of the leachate or waste
liquid and access to the pipe network for inspection and possible
repairs through the operational and post-closure care periods.
- Mechanical and electrical equipment for conveying the liquid collected
in the sump/manhole system to a separate storage or treatment area and
(in the case of landfills and waste piles) for monitoring and control-
ling the level of leachate above the top liner.
Steps in installing an LCRS can include:
- Foundation preparation.
- Bedding layer placement.
- Pipe network installation.
9-48
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- Drainage layer placement.
- Filter layer placement.
- Installation of sumps and associated structures.
- Installation of mechanical and electrical equipment.
Depending on the design, trenches may have to be constructed in which the
pipe are placed. Details on the design of LCRSs are described in Section
7.5.
9.4.1 Construction of a Secondary LCRS
The secondary LCRS for a hazardous waste containment unit is con-
structed on top of a bottom liner. If the design calls for embedded pipe,
the trenches in which the pipe are to be placed must be dug in the soil
component of the composite bottom liner before the FML component of the
composite liner can be installed. In digging the trenches, measures are
taken to monitor the thickness of an underlying soil liner so that the
required thickness is maintained. The edges of the trenches are rounded to
prevent damage to the FML. The bottom liner is placed carefully so that
there is sufficient material to line the trench. At the same time, care is
taken not to damage the low-permeability soil liner and allow loose material
to fall into the bottom of the trench. The pipe is then placed in these
lined trenches and the necessary drainage material placed around the pipe.
Geotextile can be used as a bedding material to prevent a granular drainage
material from damaging the FML liner in the trenches. A procedure for lining
an LCRS trench with a geotextile is presented in Figure 9-35.
If synthetic materials are specified in the design either for drainage
or as bedding, the materials will need to be placed in accordance with a
placement plan similar in form to an FML sheet layout. Before installing
synthetic drainage media, the underlying FML needs to be swept clear of dirt
and debris. The materials are placed to allow for sufficient overlap for
seaming and so that the material is free from wrinkles and folds. Seaming is
performed in accordance with the specified procedure. Geotextiles are
usually seamed using portable sewing equipment; geonets can be "tacked" or
"stitched" together using various mechanical means, e.g. plastic ties every
6 ft on center. An FML or geotextile should be placed on top of a geonet as
soon as possible after it has been installed to prevent wind-blown dirt and
debris from being deposited in the system.
If granular material is used in the drainage system, considerable care
must be exercised with the equipment used in placing and compacting the
granular material on top of the liner. Loose granules are removed from
the surface of the liner in order to avoid possible puncture by traffic or
personnel. Compaction of noncohesive soil materials is discussed in Section
9.2.2.
9-49
-------
FML
&!&
Soil Component
of a Composite Liner
1. EXCAVATED
TRENCH
2. PLACE FABRIC
3. ADD BEDDING
AND PIPE
4. PLACE/COMPACT
FILTER MATERIAL
5. WRAP FABRIC
OVER TOP
6. COMPACT
BACKFILL
Figure 9-35.
Schematic of sequential procedure for wrapping an LCRS trench
with a geotextile. Actual trench design will probably have
slopes less steep, and top edge of trench will be rounded.
If a composite liner is to be placed above the secondary LCRS, care must
be exercised in placing the soil component of the liner. It is recommended
that the first few lifts of soil not be compacted. Also, the succeeding
layers should be lightly compacted until a sufficient bed has been formed
that will allow full compaction. Specifications may require the top layer
contacting the top FML to have a maximum hydraulic conductivity of 1 x 10~?
cm s~l.
9.4.2 Construction of a Primary LCRS
The primary LCRS is constructed above the top liner. Granular systems
with perforated pipes can be built with the pipe network being placed on the
liner, i.e. without the use of trenches. As in constructing the secondary
LCRS, particular care must be taken while placing and compacting a granular
drainage material above the pipes in order to avoid puncturing the FML and
causing the pipe to collapse. It is recommended that the piping system be
flushed out after installation to ensure that the pipes are clear.
9-50
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9.5 ANCHORING/SEALING OF AN FML AROUND STRUCTURES/PENETRATIONS
Proper anchoring of the FML around the unit perimeter as well as con-
scientious tailoring and sealing the FML around penetrating structures are
essential to satisfactory FML performance. Generally, in cut-and-fill type
impoundments, the FML is anchored at the top of the enbankment or berm using
one of three ways:
- A trench and backfill method.
- A friction method.
- Anchoring to a concrete structure.
These different methods are presented schematically in Figure 7-30.
The trench and backfill method is the one recommended most often by FML
manufacturers, probably due to its simplicity and economy. Excavation of the
anchor trench in preparation for laying the liner is usually accomplished
with a trenching machine such as a ditch witch or by using the blade of a
bulldozer tilted at an angle. Using a trenching machine is generally con-
sidered more desirable because of the resulting trench geometry. Dirt from
the excavation needs to be spread away from the slope and smoothed to facil-
itate unrolling and spotting of the FML.
While opening and spotting the FML, provisions are made for temporarily
securing the edges of the rolls or panels in the anchor trench while the FML
is seamed. After the seaming crew has completed the seams for a particular
roll or panel, the trench is backfilled with earth that was excavated from
the trench. The trench should not be backfilled until after the rolls or
panels have been seamed so that they can be aligned and stretched, if neces-
sary, for wrinkle-free seaming. In addition, it is generally recommended
that FML seams be extended to the edge of the liner, including the bottom of
the anchor trench. If the trench (and the edge of the liner) is to be capped
with concrete curbing, it is desirable to position reinforcing rods vertical-
ly in the trench prior to backfilling. These reinforcing rods hold the FML
in place during seaming.
The perimeter of the liner can be anchored to concrete structures along
the berm or dike using anchor bolts embedded in the concrete and batten
strips composed of a material resistant to attack by the chemical(s) to be
stored in the unit. Concrete structures that come into contact with the FML
should have rounded edges and be smooth and free of all curing compounds to
minimize abrasion and chemical interaction with the FML. Anchor bolts should
be positioned not more than 12-in. apart on centers. Concrete adhesive can
be applied in a strip (minimum width 3 to 6 in., depending on the FML type)
between the liner and the concrete where the batten strips will compress the
liner to the concrete. A strip of FML (chafer strip) may be sandwiched
between the FML liner and the concrete whenever the liner contacts an angle
in the concrete structure to prevent abrasion. The batten strips are posi-
tioned over the liner and secured with washers and nuts to the anchor bolts.
9-51
-------
Mastic should be used to effect a seal around the edge of the liner. Several
alternative methods for anchoring to concrete structures are discussed by
Kays (1986).
Depending on the design and purpose of the unit, one or more types of
structures may penetrate the lining system. These penetrations can include
inlet, outlet, overflow, or mud drain pipes; gas vents; level-indicating
devices; emergency spill systems; pipe supports; or aeration systems.
Penetrations can occur in the bottom or through one of the sidewalls, depend-
ing on their function and the design of the unit. Because tailoring and
sealing the FML around structures can be difficult and offers a possibility
for failure of the liner, several manufacturers have recommended that over-
the-top pipe placement be used whenever possible.
Most manufacturers offer standardized procedures for installing (a)
seals made in the plane of the lining system, and (b) boots to be used around
penetrations. Construction around these penetrations needs to be performed
carefully to avoid damage to the lining system after long-term service due to
differential settlement, etc. If inlet or outlet pipes are introduced into
the unit through a concrete structure, the seal can be made in the plane of
the lining system. Pipe boots or shrouds are fitted over penetrating pipes
and are seamed to the liner. These designs are discussed further in Section
7.5.7.2.
9.6 CONSTRUCTION OF THE FINAL COVER
At the end of its operational period, a landfill unit is closed by the
placement of a final cover on top of the unit. The purpose of the final
cover is to minimize the entrance of water into the unit and thereby mini-
mize the generation of leachate. The construction of the final cover should
meet the design requirements and criteria discussed in Chapter 7. As in the
case of the liner system below the waste, the final cover is a multilayered
system involving several different types of materials or components. As
required by EPA guidance, the cover system should allow a transmission of
liquids less than or equal to transmission through the liner system below the
waste. Figure 9-36 presents a profile of a final cover system showing the
subcomponents that might be required by a design. Actual covers are sloped
to allow for drainage in the drainage layer and drainage of surface runoff.
It should be noted that an FML may not be required in designs for closing
nonhazardous waste landfills.
The construction of a final cover resembles the construction of the
liner system and basically requires the same type of equipment. A signi-
ficant difference between the construction of the cover system and that of
the liner system is that the cover system is constructed on a foundation,
i.e. the waste and the operational cover, that may not have the bearing
strength of the native soil on which the bottom liner is constructed.
Furthermore, the foundation for a final cover is more likely to settle
unevenly.
9-52
-------
JL
Topsoil
jVegetative layer;
Low-permeability layer:-
:-i- (compacted soil) :-i-z:
Bedding layer
(soil or geo-
textile)
FML
Geotextile
.•:--•.•*.•.•'..•.•--..-.--•,•.-•..- •-• .'-.. ••'..'••.-n |ayer
• Geotextile
Figure 9-36.
Schematic of a cover system showing the various layers that may
require placement.
The equipment used in constructing final covers tends to be smaller than
that used in larger projects such as dams and highways. Smooth rollers and
tire rollers appear to be preferable to sheepsfoot rollers in constructing
layered covers because they tend to cause less disturbance to underlying
layers.
Because of the number of factors that contribute to the successful
construction of the soil component of a final cover system, particularly
the type of foundation on which the cover system is to be constructed (i.e.
the landfill itself), construction of a test using the same materials,
construction equipment, and design requirements that would be used in the
full-scale cover construction may be required. The test section can be
tested to determine whether the performance requirements for hydraulic
conductivity and strength can be achieved given the materials, equipment, and
construction procedures proposed in the design. Of particular interest is
the vulnerability of the constructed section, e.g. to vehicular traffic.
9-53
-------
Most final cover systems are constructed in layered increments, i.e. in
layers at the time the unit is closed. However, cover systems can also be
constructed in area! increments, as is presented schematically in Figure
9-37.
A Active
1 1
ll
Portion
of
Unit
Cover
Under
Construction
Drainage Layer
Vegetative Layer
Cover Complete
FML
Figure 9-37.
Construction of a final cover system in areal
(Based on Lutton, 1986, p 89).
increments.
In the layered-increment procedure, each layer is placed individually
and completed before the next layer is added. The operational soil layer
becomes the foundation for the cover system and probably requires further
compaction before construction of the cover begins. The first layer may be
a gas venting layer which may require geotextiles above and below. The
low-permeability soil layer would be constructed in a manner similar to how
the lower component of a composite liner was constructed, i.e. compacted to
be less than or equal to a specified hydraulic conductivity value, which, in
the case of a cover for a hazardous waste landfill, is 1 x 10"? cm s~*. In
order to avoid damaging the venting layer, the initial lift should not be
compacted. Inasmuch as an FML in some designs would be placed on the low-
permeability soil layer, the top of the soil layer will require fine finish-
ing, as is described in Section 9.2.5. Subsequent layers can include a
drainage layer of granular material followed by the top soil layer on which
vegetation would be placed. Additional layers to protect the low-permea-
bility layer may also be required in the design.
Construction in the areal method proceeds as the working face of the
unit advances in subdivisions. Each layer is constructed as the fill sub-
division closes and construction of the underlying layer within that sub-
division is completed. Thus, in the areal method, the final cover system
could be in all stages of construction at the same time. Such a method would
probably provide more efficient use of the equipment, personnel, and material
flow, particularly if the owner is constructing the final cover over time
with his own personnel and equipment.
9-54
-------
During construction of the cover system, particular attention must be
placed on the workmanship around seals and penetrations of the cover system
for vents, pipes, and risers penetration. Also, special attention must be
taken in the construction around the perimeter of the cover where it joins
the liner system of the unit. These are areas that have relatively high
potential for leakage.
9.7 CONSTRUCTION OF ADMIX AND SPRAYED-ON LINERS
Admix liners refer to a variety of formed-in-place materials such
as soil cement, concrete, and asphalt concrete. Although not suitable for
use in the containment of hazardous wastes, these materials are still being
used in the management of nonhazardous materials. Sprayed-on liners refer
principally to liners made of catalytically-blown asphalt and asphalt-polymer
compositions that can be sprayed on either a prepared earth surface or a
geotextile placed on the ground. Both hot-sprayed asphalt and emulsified
asphalt compositions are included. The characteristics of these materials
are discussed in Chapter 4. Constructing liners based on the these materials
is discussed in the following subsections.
9.7.1 Asphalt Concrete
Asphalt concrete for hydraulic structures such as a pond or landfill is
similar to paving-grade asphalt concrete, but, to reduce air voids in the
concrete, well-graded aggregate with high percentages of mineral fillers and
higher asphalt content are used. Side slopes are generally 2:1. As the mix
is not subject to automotive traffic it does not need the very high stability
of paving asphalt concrete but should be stable on the side slopes when hot
(Asphalt Institute, 1976).
The foundation on which the asphalt concrete liner is constructed should
be smoothed by rollers after compacting the top 6 in. to at least 95% of
maximum density by ASTM D1557. Initially, the subgrade is treated with soil
sterilant to prevent weed growth. A prime coat of hot liquid asphalt is then
applied to the surface and allowed to cure before paving. The hot asphalt
concrete mix should be placed by spreaders equipped with hoppers and strike-
off plates or screeds. They should be capable of producing courses 10 to
15 ft wide, free from grooves, depressions, holes, etc. Ironing screeds used
with strike offs and screeds on the spreader need to be heated to at least
250°F before starting operations to prevent sticking or tearing of the
surface. Placement is planned to minimize the number of cold joints. Figure
9-38 shows a two-inch thick asphalt concrete liner being placed with road
paving equipment.
The edges of spreads are smooth and sloped for 6 to 12 in. to provide
a bonding surface with the adjacent spread. Cold surfaces are heated with an
infrared heater just before forming joints. Asphalt concrete mixtures should
be applied to slopes from bottom to top (Day, 1970). Generally, best results
are obtained when the side slopes are paved before the floor (Asphalt Insti-
tute, 1976). The asphalt concrete liner needs to be compacted as soon after
9-55
-------
Figure 9-38.
A 2-in. thick asphalt concrete liner being applied using road
paving equipment and methods. After the surface cools, a seal
coat is applied (Source: Shultz, 1982).
9-56
-------
spreading as possible. Ironing screeds, rollers, vibrators or tampers may be
used for compaction (Day, 1970). In order to achieve a permeability coef-
ficient of less than 1 x 10-7 cm s-1, a voids content of 4% or less is
required (Asphalt Institute, 1976). When a liner thickness greater than 3
inches is required, multiple courses should be applied. All joints should be
staggered in the overlying course to ensure strength and low permeability for
the liner as a whole (Day, 1970, pp 56-59).
9.7.2 Soil Cement
Soil-cement liners can be made from standard or plastic soil-cement
mixes. The latter contain more cement and water than the former. Best
results are obtained when the cement is mixed with a well-graded sandy soil
(maximum size = 0.75 in.) as the cement is the minor ingredient. Type V
sulfate-resistant cement is recommended when the soil contains sulfate as
determined by laboratory tests. The design mix should be tested by the
moisture-density relations test (ASTM D558), wet-dry test (ASTM D559),
and freeze-thaw test (ASTM D560), and be tested for permeability [e.g.
Bureau of Reclamation Test Method E-13 (Bureau of Reclamation, 1974)].
Soil cement is placed using road paving methods and equipment, but it
should not be placed when air temperatures are below 45°F. The compacted
density should be 98% of the laboratory maximum density. The compaction
should proceed so that no more than one hour elapses between the spreading
and compacting of a layer. Several stages of the installation of a soil-
cement liner are shown in Figure 9-39. The surface of a compacted layer
needs to be kept moist by fog spraying if another layer is to be applied.
The finished liner should be allowed to cure for seven days. Soil cement
must be sealed with compounds such as bituminous liquids and emulsions.
These compounds are sprayed onto the soil-cement surface after it has been
sprayed with water so that the liner reaches its maximum water absorption
level. The surface of the liner should be sealed as soon after compaction
as practical (Day, 1970).
9.7.3 Concrete and Cement
The details of procedures for construction, subgrade preparation,
placing and curing of cement concrete liners may be obtained from the Bureau
of Reclamation's Concrete Manual (1975), and from consulting engineers in
this field. However, some considerations and procedures are presented
below.
Subgrade preparation is particularly important if there is a possibility
of high hydraulic pressures against the liner. A layer of gravel or drainage
system should be placed beneath the liner. The subgrade should be well
moistened just before placing the concrete. This will help prevent the
liner from drying too quickly (Bureau of Reclamation, 1963).
Concrete mixes for pond liners need to be plastic enough to consolidate
well and stiff enough not to slip on side slopes. A concrete mix with a
slump of 2 to 2.5 in. is usually satisfactory. It is important to control
9-57
-------
Placing machine is custom built to handle 10,000 cu yd of soil-cement a day
Conveyor boom extends 100-ft to dump soil-cement mix that is
compacted by rollers in stepped lifts of 9-in
Figure 9-39. Steps in the installation of a soil-cement liner (Source: Brown
and Root, Inc., 1978).
9-58
-------
the workability and consistency of the concrete carefully; a change of one
inch in slump will interfere with the quality and progress of the work. The
maximum recommended size of aggregate is 0.75 in. or less for a liner 2.5-
in. thick. The inclusion of air-entraining agents is strongly recommended
in areas where the liner will be exposed to freezing temperatures (Bureau of
Reclamation, 1975).
Placement of the concrete may be done by slip form or the use of a
screed. Surface finishing is not necessary since it is of little useful
value in this type of situation. Curing is important. The use of accepted
sealing compounds on the exposed surface is recommended to produce satis-
factory results.
Shotcrete or gunite is cement mixed with sand of maximum size of 0.188
in., although 0.75-in. aggregate is used for some structural shotcrete. The
relatively dry mix is "shot" through a large flexible hose by pneumatic
pressure. Moist curing or use of a curing compound is necessary for shot-
crete. Gunite may be used as a liner by itself, but generally requires an
asphaltic or membrane seal to attain the required permeability (Bureau of
Reclamation, 1963).
9.7.4 Sprayed-on Liners
A basic problem in placing a sprayed-on liner is to prevent pinholes
from forming. Sprayed-on liners require a more carefully prepared subgrade
than types of admix liners. The subgrade is dragged and rolled to produce a
smooth surface free from rough, irregular, and angular projections. If the
surface cannot meet the above criterion, a fine sand or soil padding may be
necessary for proper membrane support. Geotextiles have also been used. The
site should be excavated or over-excavated and side slopes flattened to allow
for any padding necessary before liner application and for 1 to 3 ft of cover
over the membrane (Bureau of Reclamation, 1963, pp 80-82).
Catalytically-blown asphalt is heated to 200-220°C (392-428°F) and
applied at a rate of 1.5 gal yd-2 measured at 60°F to form an asphalt mem-
brane. The high softening point asphalt should not be overheated since high
temperatures may lower the softening point and change other properties
of the material. The spray bar is usually set off to the side of the dis-
tributor so that the heavy equipment does not travel over the subgrade or
newly applied membrane. To eliminate pinholes, it is recommended that three
passes be made at a rate of 0.5 gal yd-2 each for a cumulative application
of 1.5 gal yd-2 (Asphalt Institute, 1976). The final membrane is usually
about 0.25-in. thick. Sections of membrane should be overlapped 1 to 2 feet.
The newly applied hot asphalt melts the underlying layer and both cool to
form one continuous liner. The asphalt cools quickly and the next pass with
the spray bar may be made immediately after finishing the previous layer.
Care should be taken to avoid the accumulation of sand, silt, dust, or gravel
on the asphalt between applications. Foreign materials on the membrane
prevent proper bonding of layers and may cause pinholes to form.
9-59
-------
The property of rapid cooling and hardening also presents some problems
in applications. Skill and organization are required to prevent freezing of
asphalt in the lines. Spray bars should not be turned off for more than one
or two minutes at a time. All pumps, lines and bars should be cleaned with
air or distillate after each spraying operation (Day, 1970). Figure 9-40
illustrates large scale spraying equipment and the spraying of an asphalt-
rubber membrane.
Asphalt membranes can also be constructed by spraying asphalt emulsions
at ambient temperatures greater than freezing onto a prepared subgrade,
usually a supporting fabric of jute or glass fiber or a geotextile. A con-
tinuous membrane forms after the emulsion breaks and the water evaporates.
Several light applications are used, not only to avoid pinholes, but to allow
drying between coats to avoid porosity due to entrapped water.
Asphalt membranes are usually covered to protect them from mechanical
damage. Cover materials are usually earth or graded earth and gravel.
Membrane damage and leaks can occur from poor application or choice of cover
material. Blading the cover frequently folds the top of the membrane and
should be avoided. Rocks can tear or gouge the liner. Cover materials
should not be applied if the temperature is below 32°F since the membrane may
rupture from the operation (Day, 1970). Placement of a fine grained soil
cover by draglines should be done on the floor first then from bottom to top
of the side slopes. Coarser materials may then be applied. (Bureau of
Reclamation, 1963, pp 82-83).
9-60
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Figure 9-40.
Placement of sprayed-on liners Th
spray bar attached to a tanker' truck
shows the spraying of an asphaU
of Anzona Refining Company)
^f °graph shows
Wer
memb^ne (courtesy
9-61
-------
9.8 REFERENCES
ASTM. Annual Book of ASTM Standards. Issued annually in several parts.
American Society for Testing and Materials, Philadelphia, PA:
D558-82. "Test Method for Moisture-Density Relations of Soil-Cement
Mixtures," Section 04.08.
D559-82. "Methods for Wetting-and-Drying Tests of Compacted Soil-Cement
Mixtures," Section 04.08.
D560-82. "Methods for Freezing-and-Thawing Tests of Compacted Soil-
Cement Mixtures," Section 04.08.
D1557-78. "Test Methods for Moisture-Density Relations of Soils and
Soil-Aggregate Mixtures Using 10-lb (4.54-kg) Rammer and
18-in. (457-mm) Drop," Section 04.08.
Asphalt Institute. 1976. Asphalt in Hydraulics. MS-12. The Asphalt
Institute, College Park, MD. 65 pp.
Brown and Root, Inc. 1978. Largest Soil-cement Job Coats Reservoir Embank-
ment. Engineering News Record 200(23):22-24.
Bureau of Reclamation. 1963. Linings for Irrigation Canals, Including a
Progress Report on the Lower Cost Canal Lining Program. U.S. Department
of Interior, Washington, B.C. 149 pp.
Bureau of Reclamation. 1974. Earth Manual. 2nd ed. U.S. Government
Printing Office. Washington, DC. 810 pp.
Bureau of Reclamation. 1975. Concrete Manual. 8th ed. U.S. Government
Printing Office, Washington, D.C. 627 pp.
Bureau of Reclamation. 1977. Design of Small Dams. 2nd ed. Revised
reprint. U.S. Government Printing Office, Washington, DC. 816 pp.
Church, H. K. 1981. Excavation Handbook. McGraw-Hill, NY. Cited in:
McAneny, C. C., P. G. Tucker, J. M. Morgan, C. R. Lee, M. F. Kelley, and
R. C. Horz. 1986. Covers for Controlled Hazardous Waste Sites. EPA
540/2-85/002. U.S. Environmental Protection Agency, Cincinnati, OH.
554 pp.
Coates, D. F., and Y. S. Yu, eds. 1977. Pit Slope Manual Chapter 9 - Waste
Embankments. CANMET Report 77-1. Canada Center for Mineral and Energy
Technology, Ottawa, Canada. 137 pp.
Daniel, D. E., and S. J. Trautwein. 1986. Field Permeability Test for
Earthen Liners. In: Proceedings of In-Situ '86, ASCE Specialty Con-
ference on Use of In-Situ Tests in Geotechnical Engineering, Blacksburg,
VA. S. P. Clemence, ed. New York, NY. pp 146-160.
9-62
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Day, M. E. 1970. Brine Pond Disposal Manual. 0 ffice of Solid Waste Con-
tract No. 14-001-1306. Bureau of Reclamation, U.S. Department of the
Interior, Denver, CO. 134 pp.
FHWA. n.d. (ca. 1984). Geotextile Engineering Manual: Course Text.
Federal Highway Administration, Washington, D.C.
Giroud, J. P., and J. E. Fluet, Jr. 1986. Quality Assurance of Geosyn-
thetic Lining Systems. Geotextiles and Geomembranes 3(4):249-287.
Goldman, L. J., A. S. Damle, G. L. Kingsbury, C. M. Northeim, and R. S.
Truesdale. 1985. Design, Construction, and Evaluation of Clay Liners
for Hazardous Waste Facilities. EPA 530/SW-86-007F. U.S. Environmental
Protection Agency, Washington, D.C. 575 pp.
Gregg, L. E. 1960. Earthwork. In: Highway Engineering Handbook. K. B.
Woods, D. S. Berry, and W. H. Goetz, eds. McGraw-Hill, NY. pp
14-1—14-40.
Kays, William B. 1977. Construction of Linings for Reservoirs, Tanks and
Pollution Control Facilities. Wiley Interscience, John Wiley and Sons,
Inc., NY. 379 pp.
Kays, W. B. 1986. Construction of Linings for Reservoirs, Tanks, and
Pollution Control Facilities. 2nd ed. Wiley Interscience, John Wiley
and Sons, NY. 454 pp.
Koerner, R. M. A. E. Lord, R. B. Crawford, and M. Cadwallader. 1987.
Geomembrane Seam Inspection Using the Ultrasonic Shadow Method. In:
Proceedings of Geosynthetic '87, February 24-26, 1987, New Orleans, LA.
Vol. 2. Industrial Fabrics Association International. pp 493-504.
Lutton, R. J. 1986. Design, Construction, and Maintenance of Cover Systems
for Hazardous Waste—An Engineering Guidance Document. Interagency
Agreement No. DW 2193068101-1. U.S. Environmental Protection Agency,
Cincinnati, OH.
McAneny, C. C., P. G. Tucker, J. M. Morgan, C. R. Lee, M. F. Kelley, and R.
C. Horz. 1985. Covers for Uncontrolled Hazardous Waste Sites. EPA
540/2-85/002. U.S. Environmental Protection Agency, Cincinnati, OH.
554 pp.
Northeim, C. M., and R. S. Truesdale. 1986. Technical Guidance Document:
Construction Quality Assurance for Hazardous Waste Land Disposal Facil-
ities. EPA 530/SW-86-031. OSWER Policy Directive No. 9472.003. U.S.
Environmental Protection Agency, Washington, D.C. 88 pp.
Sain, C. H. 1976. Earthwork. In: Standard Handbook for Civil Engineers.
2nd ed. F. S. Merritt, ed. McGraw-Hill, NY. pp 13-1—13-36.
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Shultz, D. W. 1982. Case History for Lined Impoundment. Draft. Grant No.
R806 645-010. U.S. Environmental Protection Agency, Cincinnati, OH.
Small, D. M. 1980. Establishing Installation Parameters for Rubber Liner
Membranes. In: The Role of Rubber in Water Conservation and Pollution
Control. A symposium presented at the 117th Meeting of the Rubber
Division, American Chemical Society, Las Vegas, NV. John M. Gifford
Memorial Library and Information Center, University of Akron,, Akron,
OH. pp VII-1 - VII-46.
Spigolon, S. J., and M. F. Kelley. 1984. Geotechnical Assurance of Con-
struction of Disposal Facilities. Interagency Agreement No. AD-96-F-2-
A077. EPA 600/2-84-040. NTIS No. PB 84-155225. U.S. Environmental
Protection Agency, Cincinnati, OH.
Yamamoto, L. 0. 1987. Design and Construction of a Hazardous Waste Land-
fill. In: Proceedings of Geosynthetics '87, February 24-26, 1987, New
Orleans, LA. Vol. 2. Industrial Fabrics Association International, pp
353-364.
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CHAPTER 10
QUALITY ASSURANCE FOR THE CONSTRUCTION
OF FML LINER SYSTEMS
10.1 INTRODUCTION
As is discussed in Chapter 6, strict conformance to a well-planned
quality assurance plan for the construction of a waste containment unit
has been found by experience to be an important factor in the success of such
units. Rigorous quality assurance may make the difference between a unit
that functions with a minimum number of problems throughout its service life
and one that falls short of its minimum performance goals.
Construction quality assurance (CQA) in the context of constructing a
storage or disposal unit is a planned system of activities that provides
assurance that the unit is constructed as specified in the design (Northeim
and Truesdale, 1986, p 3). Thus, CQA refers to those activities initiated by
the facility owner that ensure that the construction of the entire facility,
including manufacture, fabrication, and installation of the various compo-
nents of the lining system, meets design specifications and performance
requirements. CQA activities include inspections, verifications, audits, and
evaluations of materials and workmanship necessary to determine and document
the quality of the constructed facility. These activities are often per-
formed by a third-party quality assurance team that is independent of the
designer, manufacturer, fabricator, installer, and owner/operator to ensure
impartiality.
CQA activities should be differentiated from construction quality
control (CQC) activities which include those activities initiated by the
designer, manufacturer, fabricator, installer, or construction contractor(s)
necessary to control the quality of the constructed or installed component
and to ensure that specifications are being met. Even though the CQC
activities will overlap with those performed in fulfillment of the CQA plan,
CQC and CQA activities are ultimately independent of each other.
The CQA plan is the facility owner's site-specific written response to
the EPA's CQA program and is submitted as part of the permit application. It
should include a detailed description of all CQA activities that will be
performed to manage construction quality in order to document the owner's
approach to CQA. The plan is developed, usually by the design engineer, in
such a way that the focus of quality assurance will be on those elements of
10-1
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the design that are critical to the function of the facility. Nevertheless,
the facility owner is ultimately responsible for the CQA plan and its imple-
mentation, just as he is responsible for all elements of the design, con-
struction, and operation of a disposal facility.
It is assumed that at the time the CQA plan is implemented the site has
been characterized adequately and that a site-specific facility design has
been evaluated and accepted by the facility owner/operator. It is also
assumed that at this time the FML and other materials to be used in the
lining system have been selected. The CQA plan covers the period beginning
with construction at the site or the manufacture of components of the lining
system, whichever is earlier, and ending with acceptance of the site by the
owner/operator. Quality assurance activities involved in ensuring the
adequate performance of a unit once it is placed in service are considered
part of management and are discussed in Chapter 11.
This chapter reviews the guidelines for CQA plans set forth in the EPA's
Technical Guidance Document, "Construction Quality Assurance for Hazardous
Waste Disposal Facilities" (Northeim and Trusdale, 1986), which discusses the
elements of a CQA plan in detail. In particular, this chapter emphasizes the
inspection activities involved in the CQA of the different components of a
completed containment unit.
10.2 THE ELEMENTS OF A CQA PLAN
The CQA plan is a written document, the exact content of which will
depend on site-specific conditions for each proposed facility. Each element
of the plan should be treated comprehensively. Even though the plan is
site-specific, at a minimum, the following elements should be included:
- Delineation of responsibility and authority.
- Statement of qualifications of CQA personnel.
- Design specifications.
- Inspection activities to be performed.
- Sampling requirements of the inspection activities.
- Acceptance/reject ion criteria and corrective measures.
- Documentation requirements.
Each of these elements is discussed briefly in the following paragraphs.
10.2.1 Delineation of Responsibility and Authority
The permitting, designing, and construction of a disposal facility
involves a large number of organizations. Those organizations involved
10-2
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directly in CQA include the permitting agency, the facility owner/operator,
the design engineer, the CQA personnel, and the construction and installation
contractor(s). The FML manufacturer may also be directly involved. These
organizations are not necessarily completely independent of each other. For
example, the facility owner/operator may also be the construction contractor.
The CQA personnel may be employees of the facility owner/operator, of the
design engineer, or of an independent firm. The installer could also be the
FML manufacturer or fabricator. Regardless of the relationships among the
organizations, the areas of responsibility and the lines of authority for
each organization need to be clearly delineated in a CQA plan. Northeim and
Truesdale (1986) list the basic responsibilities of the various parties in-
volved in CQA. Giroud and Fluet (1986) also discuss the roles and responsi-
bilities of the parties involved.
Periodic meetings and visits are necessary to ensure good communication
between all parties (Northeim and Truesdale, 1986; Giroud and Fluet, 1986).
Project meetings will benefit all those involved with the facility by ensur-
ing familiarity with facility design, construction procedures, the require-
ments of the CQA plan, and any design changes. Examples of the types of
meetings that may be held include the following:
- A preconstruction CQA meeting to resolve any uncertanties about the
design, the CQA plan, etc. This meeting should be held following the
completion of the facility design, completion of the site-specific CQA
plan, and award of the construction contract. This meeting should be
attended by the facility owner/operator, design engineer, CQA person-
nel, construction contractor, and the installer, if one has been
selected.
- Daily meetings to review progress.
- Problem or work deficiency meetings to be held as the need arises.
These meeting should be documented.
10.2.2 Statement of Qualifications of CQA Personnel
The CQA plan should identify the qualifications of the CQA officer and
the CQA inspection personnel in terms of the training and experience neces-
sary to fulfill their assigned responsibilities.
10.2.3 Design Specifications
Insofar as the purpose of a CQA plan is to verify whether or not the
various components of the facility and the completed facility itself meet the
design specifications, these specifications are a necessary part of the CQA
plan. Specifications for materials and construction are discussed in more
detail in Chapters 7 and 8.
10-3
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10.2.4 Inspection Activities to be Performed
The inspection activities to be performed in the implementation of a
CQA plan include observations and tests that ensure that the materials of
construction, the construction itself, and the installation of the various
components of the lining system meet or exceed all design criteria, plans,
and specifications. The wide range of materials of construction and the
number of different construction activities involved in constructing a
disposal facility is reflected in the number of different inspection activ-
ities that are involved in implementing a CQA plan. The areas for CQA
inspection include the earthworks (including the foundation, the embankments,
and a low-permeability soil liner in composite double-liner systems), the FML
liner (from inspection of the raw materials up through inspection of the
installed liner), and the different components of the leachate collection
systems. Each of these areas is discussed separately in Sections 10.3
through 10.5.
It is
quality of
procedures
some ASTM
the tensil
procedures
enough to
important that appropriate tests are selected for inspecting the
the construction materials and the workmanship and that the exact
to be used to test the materials are well defined. For example,
standards, such as ASTM D638* which describes methods for testing
e properties of plastics, include a range of alternative testing
. Citation of the number of a standard in a CQA plan may not be
define the exact testing procedure to be followed.
Ideally, CQA inspections and tests should meet the following criteria
(Spigolon and Kelley, 1984):
- A CQA inspection test should be a good indicator of a design quality.
- A CQA inspection test or observation should be accurate and precise.
The test results or observations should be documentable, i.e. the
results or observations should be numbers or well-defined terms or
phrases.
- The results of a CQA inspection should be available within a short
period of time so that acceptance decisions can be made without
causing interference with contractor performance.
A CQA inspection test
equipment.
should be easy to run using simple, rugged
Preferably, a CQA inspection test should be nondestructive, i.e.
should not damage the integrity of any component of the installed
lining system.
*The references at the end of this
this chapter and their titles.
chapter list the ASTM standards cited in
10-4
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The data that results from CQA inspection testing will be one of two
types: attribute-type data or measurement-type data. The type of data that
will be reported will depend on the test method, the design specifications,
and on how the acceptance/rejection criteria are stated. Attribute-type data
can be based on dichotomous classifications, e.g. pass/fail, acceptable/
defective type classifications, or, in the case of FML destructive seam
testing, classifying the results of testing seams as a film-tearing bond
break or a non-film-tearing bond break. The criterion distinguishing between
classifications should be clearly stated. In the case of FML seam testing, a
schematic of the different ways in which tested specimens can break could be
included as part of the design specifications or the CQA plan. Measurement-
type data are test values which can be used to compute summary statistics
such as means, variances, and ranges. In cases in which there are alterna-
tive means of calculating test values, the precise method for calculating
should be stated.
10.2.5 Sampling Requirements
Since it is neither possible nor economically feasible to perform
100% inspection of many materials and construction processes, the quality
of the material or process must be estimated from the results of inspecting
a representative sample of the total material or constructed facility.
Examples of this situation include estimations of the integrity of FML seams
by destructive testing and assessments of the characteristics of the soil
liner in an FML/composite double liner. For all types of QA testing, the
sampling requirements need to be stated.
Inspection and sampling requirements should include statement of the
sampling strategy, the size or the definition of the unit to be sampled, the
size of the sample itself, the sampling procedure, and the number of speci-
mens to be tested per sample. There are three basic types of sampling
strategies: 100% inspection, judgmental sampling, and statistical sampling.
One hundred percent inspection means that inspection is made continuously on
every unit of a product being manufactured or fabricated.
Judgmental sampling refers to any sampling procedure in which decisions
concerning sample size, selection scheme, and locations are based on con-
siderations not derived from probability theory. The objective of such
sampling may be to test typical samples that represent the whole, to test
zones of suspected quality, or a combination of the two. Thus, in sampling
FML seams, samples could be taken at a minimum frequency per unit of seam
length from locations assigned by the CQA inspector before seaming is started
and also from locations that are of suspected quality. The success of a
judgmental sampling plan is dependent on the knowledge, capability, and
experience of the design engineer, the CQA inspection personnel, the CQA
officer, and the project manager. Organizations that construct large numbers
of similar projects, such as the U.S. Army Corps of Engineers or the U.S.
Bureau of Reclamation, often employ judgmental sampling plans using sampling
frequencies based on years of construction experience. For example, more
intensive sampling may be required in areas where design specifications are
more difficult to meet (e.g. field seaming operations on the slopes of a
10-5
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unit). The potential weakness of judgmental sampling is that such methods
are subject to biases and sampling errors.
Statistical sampling methods are based on principles of probability
theory and are used to estimate selected characteristics (e.g. means, vari-
ance, percent defective) of the overall material or construction process.
These methods are more rational, calculable, and documentable than judg-
mental methods and are recommended whenever feasible and applicable. An
important element of all statistical methods is knowledge of the inherent
variability of the specified characteristic to be measured. This variability
can be a function of material quality, construction operations, measurement
techniques and instrumentation, and the skill of the CQA personnel. The
weakness of specific statistical sampling methods depends on the applica-
bility of the theoretical assumptions to the population to be sampled; for
example, whether the probability distribution of sample test measurements is
normal.
Knowledge about the applicability of statistical sampling methods for
the CQA of constructing a waste containment unit is not well-developed. In
practice, a balanced CQA program uses both judgmental and statistical ap-
proaches to take advantage of the lack of bias in statistical sampling
methods and the experience and judgment of qualified CQA personnel.
Sampling stategies are discussed in more detail by Northeim and Trues-
dale (1986, pp 54-69). Additional information on sampling and sampling
procedures can be found in ASTM E105 and E122 and in texts by Beaton (1968),
Burr (1976), Deming (1950), Dixon and Massey (1957), Duncan (1959), Grant
(1964), Kish (1967), and the U.S. Department of the Army (1977).
10.2.6 Acceptance/Rejection Criteria and Corrective Measures
The acceptance or rejection criteria for the inspection activities
should be stated. The type of criteria will depend on the type of data
resulting from the inspection testing. If the data being collected are
attribute-type data (e.g. film-tearing bond break/non-film-tearing bond break
for reporting the results of destructive testing of FML seams), the maximum
percentage of specimens that are unacceptable per tested sample or the
maximum percentage of unacceptable samples per sample block should be stated.
If the data being collected are measurement-type data, acceptance/rejection
criteria are based on whether a nominal level (e.g. mean, median, variance)
meets the design specification value(s) for a specific measurement (e.g. FKL
seam strength). The nature of the nominal level, e.g. whether it is a median
or a mean, should be stated in the specifications.
The criteria for accepting or rejecting measurements that appear to be
atypical or in error should be stated. This type of datum, called an out-
lier, may be an extreme manifestation of the random variability inherent in
data resulting from testing a specific material or process, or it may be a
result of a gross deviation in the test procedure or an error in calculating
or recording the numerical value. For further discussion of outliers, see
ASTM E178 or texts by Barnett and Lewis (1978) and Dixon and Massey (1957).
10-6
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When material or work is rejected because the CQA inspection activities
indicate that it does not meet the design specifications, corrective measures
must be implemented. The types of corrective measures that should be taken
and the requirements for inspecting these measures should be stated.
1C.2.7 Documentation
Thorough documentation is an important part of the implementation
and success of a CQA Plan. The documentation requirements for all CQA
activities should be described in detail in the plan. These requirements
should include such items as daily summary reports, inspection data sheets,
problem identification and corrective measure reports, block evaluation
reports, acceptance reports, and the final documentation, which is submitted
to the permitting agency. Provisions for final storage of the CQA records
should also be included in the CQA plan. Recordkeeping documentation of
geotechnical work is discussed in detail by Spigolon and Kelley (1984).
10.3 CQA INSPECTION OF EARTHWORKS AND SOIL LINER COMPONENT(S)
OF COMPOSITE DOUBLE LINERS
The importance of CQA inspection of the construction of the earthworks
which will support an FML cannot be overstressed, since FflLs are not them-
selves structural materials. Case histories on liner failures indicate that
many have occurred due to engineering and construction failures in the
earthworks rather than due to failures in the, FMLs themselves (Giroud, 1984),
as is discussed in Chapter 6. Quality assurance for earthworks and embank-
ments should focus on two areas:
- Tests/observations for evaluation of soil materials.
- Tests/observations for evaluation of workmanship.
This section briefly discusses the CQA inspection activities that
are appropriate to the construction of the foundation, the embankments, and
the soil liner component of a composite double liner. Specific test pro-
cedures that can be used and types of observations that can be made during
CQA inspection are listed in Appendix M.
10.3.1 Inspection of the Foundation
The purpose of the foundation is to provide structurally stable sub-
grades for the overlying facility components and to provide satisfactory
contact with the overlying liner and other system components. The foundation
should also be resistant to settlement, uplift, and compression, which could
distort or rupture the liner or its subsystems. The U.S. Department of the
Army (1977) recommends the following inspection activities for constructing
the foundation of hydraulic structures:
- Tests and observations to ensure the quality of compacted fill.
These tests should include index property tests that indicate or
correlate with engineering properties including, tests of weight-
volume relationships, soil classification tests, and laboratory
compaction tests.
10-7
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- Observations of soil and rock surfaces for adequate filling of rock
joints, clay fractures, or depressions, and removal and filling of
sand seams.
- Measurements of the depth and slope of the excavation to ensure that
they meet design requirements.
- Observations of stripping and excavation to ensure that there are no
moisture seeps and that all soft, organic, and otherwise undesirable
materials are removed. Proof-rolling with heavy equipment can be used
to detect soft areas likely to cause settlement and the consistency
of the foundation soil may be checked with a penetrometer or similar
device.
Construction observations should be continuous and the type of compac-
tion equipment and compaction methods used should be noted. Surveying will
be necessary to ensure that facility dimensions, side slopes, and bottom
slopes are as specified in the design. Further information on the CQA of
foundations, including discussions of specific inspection procedures and
sampling techniques, can be found in Spigolon and Kelley (1984), Bureau of
Reclamation (1974), and U.S. Army (1977).
10.3.2 Inspection of the Embankments
The purpose of embankments in waste containment facilities is to
function as retaining walls that resist the lateral forces of the stored
wastes and to provide support to the overlying facility components. Embank-
ments must be constructed with sufficient structural stability to prevent
massive failure throughout the lifetime of the facility. Embankment design
and construction focuses on strength and stability and, in most cases,
embankments are constructed from excavated fill material. Recently, geogrids
have been used to reinforce the soil to steepen embankment slopes (see
Sections 4.2.4. and 7.5.2).
CQA inspection requirements are similar to those for inspecting the
foundations. It should be noted, however, that the soil material for embank-
ments is compacted for strength and not necessarily for low permeability.
Preconstruction inspection activities can include evaluation of excavated
fill materials (which should continue throughout construction), evaluation of
the suitability of the construction equipment to perform the required level
of compaction, and construction of a test fill. Inspection activites that
should be carried out during construction include the following (Northeim and
Truesdale, 1986):
- Testing of fill material characteristics.
- Measurement of compacted lift thickness.
- Observation of clod-size reduction and material homogenization
operations (if applicable).
- Tests to verify water content (if applicable).
10-8
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- Observations of the number of passes by the compaction equipment, and
the uniformity of compaction coverage.
- Tests to verify the density of the compacted fill.
- Observations of scarification and connection between compacted fill
lifts (if applicable).
- Measurement of the embankment slopes.
Embankments can be constructed either with a zoned cross section
(i.e. with a core and shells that support the core in position and give it
strength to resist lateral forces) or with a homogeneous cross section. If
the embankments are constructed with a zoned cross section, the required CQA
inspection activities for each zone are the same as those listed above.
Additional information on the CQA of embankments, including the discus-
sion of specific inspection procedures and sampling techniques, can be found
in Spigolon and Kelley (1984), Bureau of Reclamation (1977), and U.S. Army
(1977).
10.3.3 Inspection of Soil Liners
The purpose of a low-permeability soil liner depends on the overall
liner system design. In the containment of hazardous wastes, soil liners are
presently being used as the soil component of a composite liner in a double
liner system which serves as a protective bedding material for the FML com-
ponent and which is compacted to achieve a specified hydraulic conductivity.
CQA activities prior to construction include inspection of the soil
materials to be compacted to be sure that they are uniform and as specified
in the design. If the soil materials need to be amended with other materials
(e.g. bentonite), CQA personnel should inspect the additional materials to
ensure their quality and make observations and tests to ensure that the
specified amount is added and that the materials are mixed uniformly with the
natural soil. Initial inspection of the soil can be largely visual, although
such inspection requires CQA personnel to be experienced with visual-manual
soil classification techniques. In addition, samples of the liner material
should be tested for the following properties:
- Hydraulic conductivity.
- Soil density/moisture content relationships.
- Maximum clod size.
- Particle size distribution.
- Atterberg limits.
- Natural water content.
10-9
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Tests for these properties are listed in Appendix M. Inspection of the soil
materials should continue throughout the construction process. The recom-
mendations of Gordon et al (1984) for the construction documentation of clay
liners are given in Table 10-1.
The EPA presently recommends the construction of tests fills to verify
the adequacy of the materials, design, equipment, and construction procedures
proposed for the soil liner. Several studies have indicated that field
(in-place) hydraulic conductivity of a compacted soil liner may be much
greater than would be predicted from laboratory hydraulic conductivity tests
(Herzog and Morse, 1984; Gordon and Huebner, 1983; Daniel, 1984; Boutwell and
Donald, 1982). Unfortunately, field hydraulic conductivity tests conducted
on the full-scale liner can cause substantial delays in construction and
result in other problems caused by the prolonged exposure of the soil liner
(e.g. desiccation, erosion, etc.). Determining the hydraulic conductivity of
a test liner compacted of the same soil materials in accordance with the same
construction procedures in conjunction with a strict CQA plan should allow
the performance of the full-scale liner to be predicted with the highest
degree of confidence presently available. Ideally, the test fill can also be
used to establish a correlation between index property tests (e.g. hydraulic
conductivity of laboratory compacted samples, Atterberg limits, particle-size
distribution, etc.) and field hydraulic conductivity tests, thus eliminating
the need for field hydraulic conductivity testing of the full-scale liner.
Guidelines for the construction and CQA of test fills are presented by
Northeim and Truesdale (1986). See also Section 7.5.3.1.5.
During construction, CQA personnel should observe the compaction
process (including estimating the compactive effort) continuously and test
the compacted liner in accordance with a specified sampling strategy using
specified test procedures. Tests for the CQA inspection of low-permeability
soil liners are listed in Appendix M. Further information on the CQA of
compacted soil liners can be found in Spigolon and Kelley (1984) and Goldman
et al (1985).
Since the top surface of the compacted soil liner can also serve as the
bedding layer for an FML, CQA of the finished soil liner should include
(Northeim and Truesdale, 1986):
- Observations to ensure the removal of objects such as roots, large
clods and rocks that could penetrate the FML.
- Observations to ensure uniform application of herbicides, when
required.
- Observations and tests to ensure that the surface is properly com-
pacted, smooth, uniform, and free from sudden changes in grade.
- Observations to ensure that any recessed areas in the subgrade are
properly placed.
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TABLE 10-1. SAMPLE RECOMMENDATIONS FOP CONSTRUCTION
DOCUMENTATION OF CLAY-LINED LANDFILLS
Item
1. Clay borrow source
testing
Testing
Grain size
Moisture content
Atterberg limits
Frequency
1,000 yd3
1,000 yd3
5,000 yd3
2. Clay liner testing
3. Granular drainage
blanket testing
(liquid limit and
plasticity index)
Moisture-density curve
Lab hydraulic conducti-
vity (remolded samples)
Density
(nuclear or sand cone)
Moisture content
Hydraulic conductivity
(undisturbed soil sample)
Dry density
(undisturbed soil sample)
Moisture content
(undisturbed soil sample)
Atterberg limits
(liquid limit and
plasticity index)
Grain size
(to the 2-micron
particle size)
Moisture-density curve
(as per clay borrow
requi rements)
Grain size
(to the No. 200 sieve)
Hydraulic conductivity
5,000 yd3 and all
changes in material
10,000 yd3
5 test/acre/lift
(250 yd3)
5 test/acre/lift
(250 yd3)
1 test/acre/lift
(1,500 yd3)
1 test/acre/lift
(1,500 yd3)
1 test/acre/lift
(1,50C yd3)
1 test/acre/lift
(1,500 yd3)
1 test/acre/lift
(1,500 yd3)
5,000 yd3 and all
chances in material
1,500 yd3
3,000 yd3
Source: Gordon et al, 1984.
10-11
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- Observations to ensure the uniform application of the protective soil
bedding layer should one be required, as well as observations to
ensure the proper placement of geotextiles which may be used to
protect the FML.
Wright
an FML
et al (1987)
in detail.
discuss the CQA inspection of the supporting surface for
10.4 CQA INSPECTION OF FMLS
At the present state-of-the-art of FML technology and the design and
construction of hazardous waste storage and disposal facilities, it is not
feasible to set specifications for ultimate performance which can be tested
to assure the construction of a sound facility. Such specifications can be
used for manufactured products. For example, the long-term performance of an
automotive tire, which is a complex polymeric product, can be measured by
such relatively rapid tests as tread wear, skid resistance, and various wheel
tests for durability. No short-term tests are available at present to
determine the long-term performance of a disposal facility. At the present
time, owners and designers of waste disposal and storage facilities must
depend on methods that have developed as conventions for setting specifica-
tions, quality assurance programs to cover both materials and construction,
and materials that have demonstrated the best performance.
The five basic steps from the manufacture of an FML through its instal-
lation as a liner for a waste storage or disposal facility are as follows:
- Manufacture of the raw materials.
- Manufacture of the FML.
- Fabrication of the FML into panels (if necessary).
- Transportation, handling, and storage of the FML.
- Installation of the FML, including seaming.
Each of these steps requires CQA inspection to ensure the quality of the
installed lining system.
Specific laboratory test procedures for the CQA inspection of FMLs are
discussed in Section 4.2.2.5. Methods for the nondestructive testing of
seams are discussed in Section 9.3.6.
It is assumed that at the time the CQA plan begins to be implemented,
compatibility tests were performed if they were required as part of the
permitting process. This type of testing is necessary to ensure the site
owner that the FML to be used is compatible with the waste liquid or leachate
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to be contained. As part of compatibility testing, the FML being tested
should have been fingerprinted so that it is possible to show that the FML
that was tested is equivalent to the one being installed at the facility
site. Fingerprinting of FMLs is discussed in Section 4.2.2.6.
10.4.1 Control of Raw Materials used in the Manufacture of FMLs
To assure the production of an FML of uniform and reproducible quality,
the raw materials of which it is made must also be of uniform quality. In
many situations the FML manufacturer depends upon the supplier to furnish
the proper raw materials so that the manufactured FML can meet the design
specifications. Thus, the FML manufacturer will have a set of specifications
that are agreed to by the raw material supplier to ensure a proper and con-
sistent level of quality. The raw material supplier can issue a certificate
of conformance with the agreed specifications for each lot of material.
However, the manufacturer should still perform quality control testing on the
incoming raw materials, particularly the critical materials used in the FML
compound to determine whether they meet the appropriate specifications.
Of the various raw materials that are incorporated into a polymeric
FML, the polymer is the most critical. The ultimate user of the FML,
i.e. the owner/operator of the facility to be constructed, should know that a
manufacturer of FMLs has a quality control program to ensure uniformity of
the materials. For rubbery polymers, viscosity, molecular weight, and cure
rates are typical of the properties that must be controlled. For thermo-
plastics, the viscosity and molecular weight are of particular importance.
In the case of semi crystal line polymers such as polyethylene, it is im-
portant in the production of the base resin to control the density, level of
crystallinity, melt index and composition, i.e. the ratio of ethylene to
other olefins in the polymer and the molecular weight distribution. In view
of potential batch-to-batch variation, Knipschild et al (1979) recommend that
HOPE suppliers test each batch of resin and report the following values to an
FML manufacturer: density, percent carbon black, melt index, relative solu-
tion viscosity, stress-crack resistance, and percent volatiles. Knipschild
et al (1979) also suggest that the HOPE FML manufacturer, in turn, test at
least the melt index and percent volatiles of the base resin since these two
properties can affect processing. Cadwallader (1985) suggests that an HOPE
FML manufacturer should test the melt index, density, and oxidative induction
time of the raw resin.
In addition to the polymer, the FML compound will contain other ingre-
dients, each of which will be produced to specification and will be selected
based upon experimental testing in the formulated compound by the manu-
facturer. In most cases, there will be several suppliers of the auxiliary
ingredients; the suppliers are selected by the FML manufacturer. Among the
auxiliary materials that are of particular importance are the fillers and
processing aids for the rubbers, the carbon black used with polyethylene
for ultraviolet protection, the plasticizers for some thermoplastics, and the
various antioxidants and antidegradants used in all materials. For fabric-
reinforced FMLs, specifications should be set by the manufacturer to ensure
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strength and proper pretreatment of the fabric. Composition and strength of
the fabric should also be specified.
CQA inspection of this step of FML manufacture can involve inspection
of the manufacturer's quality control program for ensuring the uniform
quality of the raw materials including inspection of any certificates fur-
nished by the raw material supplier and inspection of the FML manufacturer's
testing of the raw materials. If there are areas where the CQA officer feels
the manufacturer's quality control program is weak, he may request the manu-
facturer to conduct additional testing. The CQA officer may also conduct
additional testing to verify the manufacturer's product specifications or his
test results.
10.4.2 Inspection of the Manufactured FML Sheeting
FML compounds are mixed in various types of equipment depending on
the type of polymer; for example, rubbers and thermoplastics are generally
mixed in internal mixers and on mills. Polyethylenes are mixed on mills and
in extruder mixers. The ingredients are dispersed and the mass becomes
thermoplastic and processable on calenders and in extruders used to manufac-
ture the FML. The Theological properties, e.g. viscosity of the mixed
compound, must be controlled within specified limits in order to assure
uniform shaping. If the FML is to be exposed to the weather, particular
attention must be paid to the dispersion of the ultraviolet screen, e.g.
carbon black and the antioxidants.
The three basic methods used in the manufacture of FMLs are calendering,
extrusion, and spread coating. Calendering is used in forming both unrein-
forced and fabric-reinforced FMLs, whereas extrusion is only used in making
unreinforced FMLs, e.g. polyethylene. Spread coating is used usually for
making fabric-reinforced FMLs in which the fabric weave is comparatively
tight, i.e. the number of thread ends per inch is greater than 20. These
manufacturing processes are discussed in more detail in Chapter 4. Each
process requires a different quality control plan, and each manufacturer
should have an appropriate quality control manual that is available to a CQA
officer.
CQA testing of the manufactured FML will depend on the type of FML
being tested and the specifications which the manufactured FML has to meet.
Most of these specifications give minimum values for the FML. Testing can
include measurements of the following properties:
- Analytical properties:
--Volatiles.
—Ash content.
--Extractables.
--Specific gravity/density.
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--Crystallinity content (if FML is semi crystal line).
--Carbon black content (if FML is semi crystal line).
--Carbon black dispersion (if FML is semicrystalline).
—Melt flow index (if FML is semi crystalline).
Physical properties:
—Thickness (a minimum thickness at all points across the roll
width should be met).
—Tensile properties.
--Modulus of elasticity (if FML is semicrystalline).
--Hardness.
--Tear resistance.
—Puncture resistance, including impact puncture.
—Hydrostatic resistance.
--Scrim chracteristics (if FML is fabric-reinforced).
--Ply adhesion (if FML is fabric-reinforced).
Permeability characteristics:
-- Water vapor transmission.
— Solvent vapor transmission.
— Gas permeability.
Tests that measure environmental and aging effects:
—Resistance to ozone-cracking.
—Resistance to environmental stress-cracking (if FML is semi-
crystalline).
--Low-temperature properties.
--High-temperature properties.
—Air-oven aging characteristics.
—Dimensional stability.
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—Water absorption.
--Resistance to soil burial.
These properties and specific tests for measuring them are discussed in
Chapter 4.
For calendered FMLs, the important features of inspection include
measurement of thickness and visual inspection of the surface to ensure that
a minimum thickness in the specification is met and that the FML is free of
pinholes and surface irregularities. For fabric-reinforced FMLs, ply ad-
hesion and thickness of the coating over the scrim should be measured as the
FML is being manufactured. The distance from the selvage edges of the fabric
with respect to the edge of the sheeting should be inspected during manu-
facture to make sure it meets specification. Also, during the processing a
visual inspection must be maintained to avoid deformation of the fabric.
Measurements of ply adhesion are particularly needed on FMLs manufactured
with fabrics with high thread end counts, due to the reduced area for strike
through.
The manufactured FML should be fingerprinted by the CQA laboratory and
the results compared with the fingerprint of the FML tested in the compati-
bility study to ensure that the FML used in the final construction is of the
same composition.
An important aspect of CQA inspections of manufactured FMLs is the level
of sampling. There are two types of sampling to consider: (1) the level at
which samples can be taken from the manufactured FML, i.e. the number and
size of sample removed per FML roll, and (2) the level of testing to perform
per sample. At this time most sampling is performed on a judgmental basis.
The sampling of the rolls for property testing is often coordinated with the
manufacturer's quality control sampling which usually occurs either at the
beginning or end of a roll and sometimes somewhere in the middle, depending
on production procedures. In the case of FMLs that are fabricated into
panels, the FML can also be sampled during fabrication so that samples can
include factory seams. The level of testing and the type of tests to perform
on the sample will depend on the type of FML and the production process. CQA
testing should concentrate on testing those properties which are important
to FML performance and those which are subject to variability due to vari-
ations in production conditions or compound composition. For example,
the most frequently performed testing will probably be measurements of
thickness. In the CQA inspection testing of a fabric-reinforced CPE FML, the
Bureau of Reclamation performed a clearly defined level of testing per sample
of the CPE liner installed at the Mt. Elbert Forebay Reservoir, as is shown
in Table 10-2 (Morrison et al, 1981). The samples taken during fabrication
of the panels were perpendicular to the factory seams. Each sample, which
measured approximately 1 x 70 or 140 ft depending on panel design size, was
long enough to include all the factory seams in that panel. One out of every
10 panels was sampled out of an estimated 1,000 panels that were required for
the entire project. The required level of sampling and testing should be
stated in the CQA plan.
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TABLE 10-2. SPECIFICATIONS AND THE NUMBER OF SPECIMENS TESTED PER
SAMPLE OF A CPE FML USED IN CONSTRUCTION OF MT. ELBERT FOREBAY RESERVOIR
Property
Thickness
Breaking strength,
each direction
Tear strength,
each direction
Test Method
ASTM D751
ASTM D751,
Grab Method A
ASTM D751,
Tongue Tear
Method B
Minimum
requirement
1.04 mm
(0.041 in.)
8.90 N
(200 Ibf)
334 N
(75 Ibf)
Number of
specimens tested
per panel3 sample
(Random readings)
5 (warp direction)
5 fill direction)
5 (warp direction)
5 (fill direction)
Bonded seam strength, ASTM D751,
in shear Grab Method A
Bonded seam strength,
in peel
Dimensional stability
(percent change,
maximum)
Low temperature
bend
ASTM D1876
ASTM D1204,
1 hour at 100°C
(212°F)
ASTM D2136,
3-mm (1/8-in.)
mandrel;
4 hours at
-40°C (-40°F)
Equals parent 5
material break-
ing strength
No specification 5
requirement
2% 2
Pass
Hydrostatic
resistance
Ply adhesion
Infrared spectro-
scopy
Total specimens
per panel
ASTM D751,
Method A
ASTM D413,
Machine Method
Type A specimens
Manufacturer
laboratory
procedure
2.07 MPa
(300 lb/in.2)
1400 N/m
(8 lb/in.)
Matching IR
scan
5
5
2
49
aPanels were supplied in two shapes: (1) 200 x 70 ft, containing 14 seams,
or (2) 100 x 140 ft, containing 29 seams. One out of every 10 panels was
sampled out of an estimated 1,000 panels that were required for the entire
project.
Source: Morrison et al, 1981, p 21.
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A CQA officer should visit the FML manufacturing plant prior to or
during manufacture of the FML rolls for the specific project. During this
visit the CQA officer should review the manufacturing process and the
quality control and testing procedures and make arrangements to coordinate
CQA inspection activities with the manufacturer. Some CQA plans have
required the manufacturer to submit laboratory test reports on physical
properties (including copies of appropriate stress-strain curves) for each
day's production. An important part of such a requirement is the inspection
and approval of the manufacturer's testing procedures and facilities. The
CQA officer should also inspect documentation so that it is possible to
coordinate inspection test results with the FML being installed at the
site.
Criteria for the rejection of FMLs should be set in the design step
as part of the specifications. For example, FMLs could be rejected on
the basis of not meeting the specifications for physical properties, composi-
tion, and thickness. Polyethylene FMLs should be rejected on the basis
of inadequate thickness and carbon black content and dispersion; fabric-
reinforced FMLs should be rejected for inadequate ply adhesion and insuf-
ficient thickness of coating over fabric.
10.4.3 Inspection of Fabricated Panels
To reduce the amount of field seaming to a minimum, narrow-width FMLs
are fabricated into panels under factory conditions. Each panel is made
according to a design layout for the liner and is numbered and identified for
installation. The size of the panels is limited by weight, and the ability
of a crew to install them in the field. These panels range from 2,000 to
5,000 Ibs and up to 100 x 200 ft (30 x 60 m). It is desirable to reduce the
amount of field seaming because seaming procedures and conditions can be
controlled more precisely in a factory. Methods of seaming FMLs are dis-
cussed in Section 4.2.2.3. It should be noted that PE FMLs are brought to
the site in rolls rather than panels and require a crane or front-end loader
for moving to the installation site. These rolls may weigh up to 10,000
pounds.
CQA inspection of panel fabrication should concentrate on the inspection
of the seams which should be 100% nondestructively tested for continuity.
Methods for the nondestructive testing of seams are described in Section
9.3.6. A CQA officer should visit the fabrication site to review the fabri-
cator's quality control procedures and facilities for testing. In parti-
cular, he should review:
- The levels of inspection of the FML for pinholes and other surface
imperfections during fabrication of the panels.
- The nondestructive testing of the panel seams, e.g. by air-lance.
- Quality control procedures involving destructive testing of seams.
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- The handling of the fabricated FMLs as they are prepared for shipment.
- The clarity of the directions for placement of the panels or rolls at
the job site and the directions for unfolding or unrolling of each
individual panel.
- The document control.
The quality control procedures involving destructive testing of seams can
include testing of samples removed from fabricated panels and testing of
prestart seam samples, i.e. samples that are made at the beginning of a shift
on extraneous pieces of FML to test the fabricating personnel and their
equipment. Heat-sealed seams can be tested almost immediately. For CQA
testing, specifications may require conditioning of seam samples for 24 hours
at 23°C (73.4°F) before testing. Seams fabricated using solvent-based
methods must wait until the solvent has evaporated. NSF (1985) specifies
that adhesive-seamed samples (including those seamed with bodied solvents)
should be conditioned for a minimum of 12 days at 23°C (73.4°F); at the
end of this period if the seam does not appear dry or suitable for testing,
the seam samples can then be conditioned in an air-circulating oven at 70°C
(158°F) for 3 hours and allowed to rest at 23°C (73.4°F) for 48 hours before
testing. The hole remaining from sampling a fabricated panel must be
patched, generally with a bodied-solvent adhesive for noncrystalline thermo-
plastic or by fillet-extrusion welds for PE FMLs.
The level of sampling for the CQA destructive testing of seams will
depend on the CQA planner's judgment about the level of variation inherent in
the seaming procedure and on the size of the entire job. As is described in
the previous subsection, the Bureau of Reclamation took a 1-ft wide sample
that ran perpendicular to the seam from an edge of one out of every 10 panels
used in constructing a reservoir (Morrison et al, 1981). In this way, each
sample had a section from every seam in the sampled panel. At the CQA
laboratory, each sample was visually inspected for:
- Sufficient seam overlap to ensure specified scrim-to-scrim bonding.
- Sufficient adhesion of the overlap to ensure that the selvage was
fully bonded to the adjacent panel.
Five specimens were randomly cut and tested for shear and five for peel from
each sample. For jobs in which the size and shape of the panels varies,
sampling can also be performed on the basis of a specified number per linear
foot of seam, e.g. one destructive sample per 1,000 ft of seam. Wright et al
(1987) report that one factory seam sample per 1525 m (5,000 ft) of factory
seam is normally required.
10.4.4 Inspection of Transportation, Handling, and Storage of FMLs
FMLs are usually shipped and stored at the site before being installed.
The basic function of CQA inspection at this stage is to ensure that no
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damage occurs to the FML and to ensure that what damage does occur is noted
and evenutally repaired. In particular, the CQA officer inspects the storage
facilities and the conditions under which the FML is transported. Depending
on the FML type, the CQA officer may need to pay particular attention to high
temperature and other environmental conditions during storage prior to
shipment, during shipment, and at the site prior to installation. Some FMLs,
e.g. those based on CSPE and CPE, are sensitive to moisture and heat; these
FMLs can partially crosslink (making the FML more difficult to seam) or block
(a phenomenon that occurs when an FML sticks to istelf while being stored
rolled or folded, resulting in delamination or ripping when the FML is
unrolled) under improper storage conditions before being installed in the
field. A CQA officer should inspect all facilities intended for storage of
FMLs. In cases where the FML will be stored in direct contact with the
ground, the CQA officer should inspect the ground surface to ensure that it
is relatively level, smooth, and free of rocks, holes, and debris.
The CQA officer should inspect the manufactured rolls or fabricated
panels to ensure that their identification labels include the following,
depending on the type of FML:
- Name of manufacturer/fabricator.
- FML type, including polymer type and details of construction (e.g.
number of plies, type of scrim, nominal thickness, etc.).
- Manufacturing batch code (of rolls).
- Panel number or placement according to the design layout pattern.
- Date of manufacture (of rolls) or date of fabrication (of panels).
- Physical dimensions (length and width).
- Directions for unrolling or unfolding of the FML.
For FMLs that have been fabricated into panels, documentation identifying the
rolls used in a specific panel may also be required so the results of CQA
inspection testing of the rolls can be correlated with the panels being
installed in the facility.
Once the FML is received at the job site, all documentation should be
checked to verify receipt of the FML. The FML should be inspected to ensure
that it is not damaged and that any damage that has occurred is noted and
corrected. In addition, the auxiliary materials that are used in the seam-
ing, e.g. adhesives or welding materials, should be visually inspected to
ensure that the correct materials are on hand as required by specifications.
Other considerations in the CQA of on-site unloading and storage of FMLs
are discussed by Wright et a! (1987).
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10.4.5 Inspection of FML Installation
Installation of the FML involves bringing the FML to the site, unrolling
or unfolding it, seaming the adjacent panels or sheets together, anchoring
the FML in trenches or attaching it to a structure, and finally covering the
liner with an upper bedding layer as required by the design. CQA activities
involved in each of these steps are discussed in detail by Wright et al
(1987). CQA inspection of the leachate collection and removal systems is
described in Section 10.5.
10.4.5.1 Inspection of FML Placement--
Placement of the FML at the job site involves:
- Transporting the rolled or folded FML to the work area.
- Removing the FML from the packaging.
- Spreading the FML over the subgrade in accordance with the design
layout pattern.
CQA inspection of the placement of the FML should include:
- Final inspection of the subgrade surface and the anchor trenches.
- Inspection of the equipment for unloading the FML, including making
sure that it is of the appropriate type and that an appropriate
quantity is available at the site.
- Checking the number and qualifications of the personnel involved in
laying out the FML and the appropriateness of their clothing (e.g.
gloves, footwear, etc.).
- Making sure that proper procedures are followed during FML layout,
including making sure that the FML is laid out under the proper
weather conditions.
- Confirming that placement of panels or rolls is in accordance with
the design layout plan. In cases in which specific rolls are not
assigned specific placement in the plan, the "as built" drawings
should identify the actual placement of individual rolls.
- Visually inspecting the entire surface of each roll or panel for
tears, punctures, etc., as it is placed. Any defects that are noticed
should be marked for repair.
- Cutting out a sample of the FML and giving it to the owner/installer
for future reference.
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- Confirming that the overlap between adjacent rolls or panels meets
specification and making sure that there is proper temporary anchorage
of the FML prior to seaming and covering.
- Keeping a daily record of weather conditions and other factors, such
as those indicated in the next section.
In addition, photographing the critical steps in the liner installation is
also recommended.
10.4.5.2 Inspection of FML Field Seams--
The success or failure of the liner installation depends to a great
extent on the integrity of the field seams. As is discussed in Section
9.3.5, job site factors have been found to influence field seaming oper-
ations, which are largely manually controlled (i.e. they are not automated)
include:
- The ambient temperature at which the seams are produced.
- The relative humidity.
- The amount of wind.
- The effect that clouds have on the FML temperature.
- The moisture content of the subgrade underneath the FML.
- The supporting surface on which the seam is bonded.
- The skill of the seaming crew.
- The quality and consistency of the adhesive, if an adhesive is used.
- Proper preparation of the FML surfaces to be joined.
- The cleanliness of the seam interface, i.e. the amount of airborne
dust and debris present.
- The ease in handling seaming equipment, if seaming equipment is used.
Inspection activities that should be documented during field seaming
operations include (Northeim and Truesdale, 1986):
- Observations to ensure that the FML is free from dirt, dust, and
moisture.
- Observations to ensure that the seaming materials and equipment are as
specified.
- Observations to ensure that a proper foundation is available for
seaming.
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- Observations of weather conditions (e.g. temperature, humidity, wind)
to ensure that they are acceptable for seaming.
- Measurements of temperatures, pressures, and speed of seaming,
when applicable, to ensure that they are as specified (e.g. gages
and dials should be checked and readings recorded).
- Observations to ensure that the FML is not damaged by equipment or
personnel during the seaming process.
All seams should be subjected to 100% visual inspection and to non-
destructive testing in accordance with the CQA plan. Methods of non-destruc-
tive testing are discussed in Section 9.3.6. These methods are basically to
measure the continuity of the seams and include vacuum box, air pressure,
ultrasonic spark, and air-lance, and probe methods. Depending on the method
of seaming and the type of testing, seams may need time to develop strength
before being tested.
Since nondestructive tests only measure seam continuity and not seam
strength, seam samples should also be subjected to destructive testing.
Samples should be taken on a frequency basis. The minimum number of samples
per seam length per seam crew and the procedures for determining sample
locations should be stated in the CQA plan. For example, Wright et al (1987)
report that one destructive seam sample per 152.5 m (500 ft) of field seam
is normally required. Additional samples may also be required at the dis-
cretion of the CQA officer due to suspicions about contamination by dirt or
moisture, variations in appearance, changes in seaming materials, an increase
in failures resulting from nondestructive testing, etc. The level of sampl-
ing ultimately should depend on the level of variability in the seaming
procedure. Thus, different seaming procedures may require different levels
of sampling. In addition, the level of sampling may also depend on the
location of the installed liner. For example, more samples may be required
on the slopes where more difficulties in seaming arise than on the level part
of the liner at the bottom. As field seaming techniques become more auto-
mated, the required level of sampling may decrease.
There are two types of samples that can be tested destructively: samples
that are cut directly out of the installed liner (destructive samples) and
samples that are made separately alongside the actual seam at the time the
seam was made (nondestructive samples). Nondestructive samples include both
field-fabricated start-up seam samples and random field-fabricated samples,
as required in the specification. Start-up samples are made at the beginning
of a shift using the same methods and equipment as those used to seam the
installed liner. Random field-fabricated samples can be made either on a
frequency basis (i.e. one per unit length of actual installed seam) or at the
discretion of the CQA inspector. These seams should be made by the same
personnel under the same conditions using the same techniques and equipment
as those used in seaming the actual liner at the time the sample is request-
ed. The limitation of nondestructive sampling is that the test results
give only a partial indication of the quality of the actual seam. They
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indicate whether the personnel or seaming equipment performed adequately
the time and under the conditions of sample fabrication.
at
On the other hand, destructive sampling, which allows testing of the
actual fabricated seam, results in damage to the liner in the process of
taking the sample which must be repaired. Because of this damage to the
liner, Wright et al (1987) recommend nondestructive sampling over destructive
sampling of field seams except in the following situations:
- When there is an insufficient number of CQA inspectors to observe
each seaming crew full-time.
- When the results
seam qua!ity.
of testing nondestructive samples indicate poor
Nevertheless, they recommend testing a minimum of one destructive sample per
seaming crew per day per day. Most specifications covering liner instal-
lation and seam testing require some destructive sampling.
In fabricating nondestructive samples, care should be taken so that
there is sufficient free overlap to allow peel testing of the seam. At the
time a destructive sample is taken, or a nondestructive sample is fabricated,
its location in the liner or in relation to the actual seaming should be
indicated on the "as-built" drawing.
The required size of the seam sample for destructive testing will depend
on the number of parties involved in testing that particular sample. Samples
can be tested in the field by a field tensometer, tested by the CQA labora-
tory, and tested by the installer's laboratory. In addition, a portion of
the sample may be retained for the facility owner's archives for future
reference. For full testing by a single laboratory (five specimens in peel
and five in shear), an 18-in. length of seam is needed for unreinforced FMLs
and a 30-in. length for fabric-reinforced FMLs. The minimum width is 6 in.
of FML on
width).
both sides of the seam plus the seam width (i.e. 1 ft plus the seam
Identification of samples
the following:
sent to a QC/QA laboratory should include
- Type of FML, including thickness.
- Project name.
- Cell identification, if a liner is being installed in more than one
cell at a particular facility.
- Seam identification or identification of adjacent panels and location
on seam so that the location from which the sample was taken can be
easily identified on the site layout pattern.
- Crew identification.
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- Machine identification (if applicable).
- Date of fabrication.
The date of fabrication is particularly important in testing seams made with
adhesive- or solvent-based methods so that the samples can be tested after
the correct amount of time.
For the purposes of CQA testing, the test area of the seam may need to
be precisely defined. For example, in the seaming of HOPE FMLs using fillet-
weld techniques, the two sheets to be seamed together are sometimes tacked
together by thermal means. Since the hot-tack operation is usually a rel-
atively uncontrolled operation, the hot tack area should not be considered
part of the seam and should be delaminated prior to testing, when possible.
In performing CQA destructive testing of field seam samples, laboratory
testing of the samples is ultimately preferred over field testing because
of the greater control over the testing conditions that is possible in a
laboratory. Variations in test conditions could significantly affect test
results. CQA inspection testing of seams will always ultimately rely on
laboratory results.
The criteria for passing or failing a seam sample should be stated
clearly. Examples of criteria include:
- The average of all test values for a sample has to be greater than
or equal to specified values in both peel and shear modes.
- The median of the test values for a sample has to be greater than
or equal to specified values in both peel and shear modes. In the
case where the number of specimens tested per sample per test equals
five, at least three specimens would have to have test values greater
than or equal to the specified value.
- Specifying a minimum number of specimens per sample that must result
in test values greater than or equal to specified values in both
peel and shear modes.
- Specifying a minimum number of specimens per sample that must result
in the type of break required in the specifications, e.g. a film-
tearing bond break, in both peel and shear modes.
The specific pass/fail criteria stated in the CQA plan will depend on how
the specification requirements for the field seams are stated, i.e. on
whether they are stated as minimum values, a type of break, or both.
Information about the specific ways in which specimens broke during
destructive testing has been found to be valuable in determining whether a
specific break is acceptable. As an aid to classifying the various types of
breaks that occur in testing individual specimens, a series of locus-of-break
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codes are presented in Appendix N for various types of seams. It is sug-
gested that the appropriate group of locus-of-break codes be incorporated in
the specifications along with a minumum stress-at-break value for both peel
and shear modes.
Documentation of the seam test results (both destructive and nondestruc-
tive) should show that all field seams meet design specifications (Section
8.5.4). In case of any test sample failure, either by destructive or non-
destructive testing, the procedures for performing the necessary corrective
measures on the installed FML, e.g. capping, should be stated in the CQA
plan. These corrective measures may depend on the type of sample failure.
In the EPA Policy Directive on the CQA of hazardous waste land disposal
facilities, Mortheim and Truesdale (1986) state the following:
For field seams that fail [the test], the seam can either be
reconstructed between the failed and any previous passed seam
location or the installer can go on either side of the failed
seam location (10-ft minimum), take another sample, test it and
if it passes, reconstruct the seam between the two locations.
If it fails, the process should be continued. In all cases,
acceptable seams must be bounded by two passed test locations
(p 36).
The repair of all seam failures should be documented.
10.4.5.3 Inspection of FML Anchors and Attachments--
All FMLs will need to be anchored in place around the perimeter of
either the site or the specific cell. Failure of a perimeter anchor can lead
to the collapse of a major portion of an FML installation. CQA personnel
should observe anchor excavation and anchoring of the FML to ensure the
following (Wright et al, 1987):
- Trench depth and width (and distance from slope, if applicable) meet
specifications.
- The leading edge of the trench is smooth and free of sharp of jagged
edges.
- Temporary anchoring methods (sand bags) do not damage the FML.
- FML is properly installed in the trench.
- Earth fill for the anchor trench is free of sharp rocks.
- Final backfilling and compaction operations do not damage the FML.
When a design requires penetrations through the FML (e.g. structures and
pipes), CQA personnel must ensure that the attachments to the penetrations
10-P6
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are of sufficient strength and form liquid-tight seals. Inspections that
also should be made on all attachments include:
- Observations to ensure that the materials (e.g. the pipe boots or
the sealing compounds) are compatible with the waste liquid and
are as specified.
- Observations to ensure that all objects placed adjacent to the FML are
smooth and free of objects or conditions that may damage the FML.
10.4.5.4 Large-Scale Hydrostatic Leak-Detection
Test of Installed FML —
Though a performance specification is not part of the overall speci-
fication, ultimately the operater/owner of a waste impoundment facility needs
to be assured that the facility he is accepting and placing into service is
liquid-tight and that the leak detection and drainage systems perform
satisfactorily. None of the tests that are performed during the course of
the quality assurance testing from the design through the final construction
of the containment unit indicates the final performance of the liner. They
indicate the compatibility of the liner with the waste, that the composition
is satisfactory, and that the seams have passed inspection and destructive
tests. The ultimate test is when the site is placed in service and moni-
tored for a period of time. An actual measure of the performance of a con-
tainment unit is desirable and is a long-term goal of the liner industry.
The performance of a liner for a lined waste containment unit can, in
some situations, be assessed before actual wastes are placed. For example,
before a protective cover is placed on the liner (if required), the com-
pletely lined unit can be partially filled with water and observations made
as to whether losses exceed evaporative losses. An electrical leak location
method such as the one described by Darilek and Parra (1988) can also be used
to detect and locate leaks. This technique is described in more detail in
Section 11.5.3. If a leak-detection system underlies the liner, as is the
case of a top liner in a double liner system, a leak could be detected by the
presence of water in the sump. As the bottom liner in a double liner system
will probably not have a leak-detection system below it, the evaporative
method or the electrical leak location method might be used to indicate
possible leakage.
To avoid false-positive results when partially filling a lined impound-
ment to detect leakage, it may be desirable to introduce a tracer in the
water above the liner under test to ensure that the water that is observed
in the leak-detection system in reality came from the test water. It would,
of course, be more desirable if a facility could be filled with the test
water to ascertain if there are any leaks in the system, especially xin the
slopes where most seaming problems occur.
The limitations of this procedure include the costs for pumping water,
both in and out of the unit, and the delay in the construction schedule.
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10.4.5.5 Inspection of the Placement of a Protective
Cover Over the FML--
Depending on the type of liner, containment, or disposal facility and
its design requirements, a layer of soil may be placed on top of the FML to
protect it from weather conditions, equipment, and vandalism. Prior to
placement of the soil cover, the liner should be inspected for any damage
that occurred during installation. Any damage that is found should be
corrected by the specified patching procedure, and the patch should be
nondestructively tested. Ideally, the FML should not be covered until the
FML installation is completed and accepted. However, on large jobs, portions
of the liner may need to be accepted and covered prior to completion of the
entire liner.
CQA inspection activities during placement of the soil cover should
include:
- Observations and tests to ensure that the cover material meets
specifications (e.g. as defined by the soil index tests. See Spiaolon
and Kelley, 1984).
- Observation to ensure that the cover material is free of rocks,
sticks, and other items that could damage the FML.
- Observation of the use of equipment to unload and spread the cover
material to ensure that the equipment does not damage the FML.
- Measurements to ensure that the entire liner is covered with the
specified thickness of material (e.g. using grade sticks, marked
measuring staffs, surveying techniques, etc.).
In cases in which other types of protective covers are used (e.g.
geotextiles or portland cement concrete), or if the soil protective cover is
placed on top of a leachate drainage and collection system, these inspection
activities will have to be adapted accordingly.
10.5 INSPECTION OF THE INSTALLATION OF THE LEACHATE
COLLECTION AND REMOVAL SYSTEMS
The purpose of a primary leachate collection and removal system (LCRS)
in a landfill is to minimize the hydraulic head on the top liner during
operation of the unit and to remove liquids from the unit up through the end
of the post-closure care period. The purpose of a secondary LCRS (also known
as a leak-detection system) between the two liners of a landfill or surface
impoundment is to rapidly detect, collect, and remove liquids entering the
system up through the end of the post-closure care period.
An LCRS is comprised of a number of subcomponents including:
- A drainage layer.
10-28
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- A filter layer.
- A pipe network for collecting leachate or waste liquid from the
drainage layer and transporting it to the sump/manhole system.
- A bedding layer for the pipe network.
- A sump/manhole system which allows collection of the leachate or
waste liquid and access to the pipe network for inspection and
possible repairs throughout the monitoring periods.
- Mechanical and electrical equipment for conveying the leachate
from the collection system to a separate storage or treatment
area and for monitoring and controlling the level of leachate
above the liner.
The CQA inspection plan for each site will be site-specific because of the
number of options that are available to the facility designer. Nevertheless,
CQA inspection will still include observation and testing of the various
materials used in constructing the collection system(s) to ensure that they
meet or exceed design specifications. It is assumed that the materials that
are being installed have been tested for compatibility with the waste liquid
or leachate to be contained. It is also assumed that, in the case of the
polymeric materials, the materials have been fingerprinted so that it can be
shown that the materials being installed are equivalent to those that were
tested for compatibility. In addition, CQA inspection should be performed
throughout the construction of the LCRS to ensure that materials were in-
stalled according to specification. Steps in the installation of an LCRS
include:
- Foundation preparation.
- Bedding layer placement.
- Pipe network installation.
- Drainage layer placement.
- Filter layer placement.
- Installation of sumps and associated structures.
- Installation of mechanical and electrical equipment.
Foundation preparation is critical. The horizontal and vertical alignment of
the foundation should be measured prior to placement of drainage materials to
ensure that the leachate will be able to flow toward the sump (Bass, 1986).
All granular materials that will contact the FML should be inspected to
10-29
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ensure they do not contain objects that would damage the FML. In addi-
tion, all granular materials used in the LCS should be inspected for fines
which could clog the system.
When the pipe network is installed, the layout should be observed by
CQA personnel to determine whether it conforms to the design drawings, and
observations and tests should be made to ensure that all pipes are joined as
planned. Integrity of all joints should also be determined. Television
equipment mounted on skids can be used to verify that the alignment and
overall condition of the line is satisfactory. If the pipes were not
adequately protected from soil fines during construction, the pipe network
may need to be flushed to remove any debris that may have accummulated and to
verify that the lines are open. Standard sewer cleaning equipment can be
used to determine if any pipe segments have been crushed or damaged during
placement of bedding and drainage materials. Backfilling and compaction over
the the collection network must be observed by CQA personel to ensure that
damage to the pipe network has not occurred. Bass (1986) recommends a second
inspection of the liner using photographic or television equipment after
compaction of the first layer of waste or soil. When manufactured materials
such as geosynthetics and geonets are used, they should be inspected to
ensure the overlaps and field seams or other joining methods have been
performed as specified. If geonets are included in the design, the placement
of the layer directly above the geonet should be observed to ensure that
debris does not enter the drainage system.
All electrical controls within the LCRS should also be inspected. All
pumps must be tested to ensure that they are operating at rated capacity,
and any monitoring equipment must be thoroughly checked out to determine
conformance with specifications.
Appendix M lists CQA activities for the placement of leachate collection
systems.
10.6 REFERENCES
ASTM. Annual Book of ASTM Standards. Issued annually in several parts.
American Society for Testing and Materials, Philadelphia, PA:
D413-82. "Test Methods for Rubber Property--Adhesion to Flexible
Substrate," Section 09.01.
D638-84. "Test Method for Tensile Properties of Plastics," Section
08.01.
D751-79. "Method of Testing Coated Fabrics," Section 09.02.
D1204-84. "Test Method for Linear Dimensional Changes of Nonridgid
Thermoplastic Sheeting or Film at Elevated Temperature,"
Section 08.01.
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01876-72(1983). "Test Method for Peel Resistance of Adhesives (T-Peel
Test)," Section 15.06.
D2136-84. "Methods of Testing Coated Fabrics—Low Temperature Bend
Test," Sections 09.01 and 09.02.
E105-58(1975). "Recommended Practice for Probability Sampling of
Materials," Sections 04.03, 07.01, and 14.02.
£122-72(1979). "Recommended Practice for Choice of Sample Size to
Estimate the Average Quality of a Lot or Process," Section
14.02.
E178-80. "Recommended Practice for Dealing with Outlying Observations,"
Section 14.02.
Barnett, V., and T. Lewis. 1978. Outliers in Statistical Data. John Wiley
and Sons. New York. Cited in: Northeim, C. M., and R. S. Truesdale.
1986. Technical Guidance Document: Construction Quality Assurance for
Hazardous Waste Land Disposal Facilities. EPA 530-SW-86-031. OSWER
Policy Directive No. 9472.003. U.S. Environmental Protection Agency,
Washington, D.C. 88 pp.
Bass, J.. 1986. Avoiding Failure of Leachate Collection and Cap Drainage
Systems. EPA 600/2-86-058. NTIS PB 86-208733/AS. U.S. Environmental
Protection Agency, Cincinnati, OH.
Beaton, J. L. 1968. Statistical Quality Control in Highway Construction.
Jounral of the Construction Division. ASCE. 94(C01):837-853. Cited
in: Northeim, C. M., and R. S. Truesdale. 1986. Technical Guidance
Document: Construction Quality Assurance for Hazardous Waste Land
Disposal Facilities. EPA 530-SW-86-031. OSWER Policy Directive No.
9472.003. U.S. Environmental Protection Agency, Washington, D.C. 88
PP.
Boutwell, G. C., and V. R. Donald. 1982. Compacted Clay Liners for Indus-
trial Waste Disposal. Presented at ASCE National Meeting, Las Vegas,
NV. April 26, 1982. Cited in: Northeim, C. M., and R. S. Truesdale.
1986. Technical Guidance Document: Construction Quality Assurance for
Hazardous Waste Land Disposal Facilities. EPA 530-SW-86-031. OSWER
Policy Directive No. 9472.003. U.S. Environmental Protection Agency,
Washington, D.C. 88 pp.
Bureau of Reclamation. 1974. Earth Manual. 2nd ed. U.S. Government
Printing Office, Washington, D.C. 810 pp.
Bureau of Reclamation. 1977. Design of Small Dams. 2nd ed., \Revised
Reprint. U.S. Government Printing Office, Washington, D.C. 816 pp.
10-31
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Burr, I. W. 1976. Statistical Quality Control Methods. Marcel Dekker,
Inc. New York. Cited in: Northeim, C. M., and R. S. Truesdale.
1986. Technical Guidance Document: Construction Quality Assurance for
Hazardous Waste Land Disposal Facilities. EPA 530-SW-86-031. OSWER
Policy Directive No. 9472.003. U.S. Environmental Protection Agency,
Washington, D.C. 88 pp.
Cadwallader, M. W. 1985. Quality Control Objective: Manufacturer/Installer
Cooperates with Third Party. Geotechnical Fabrics Report 3(5):8-10,12.
Daniel, D. E. 1984. Predicting Hydraulic Conductivity of Clay Liners.
Journal of Geotechnical Engineering. 110(2)-.285-300.
Darilek, G. T., and J. 0. Parra. 1988. The Electrical Leak Location Method
for Geomembrane Liners. In: Land Disposal, Remedial Action, Inciner-
ation and Treatment of Hazardous Waste, Proceedings of the Fourteenth
Annual Solid Waste Research Symposium. U.S. Environmental Protection
Agency, Cincinnati, OH. (In press).
Deming, W. E. 1950. Some Theory of Sampling. John Wiley and Sons, Inc.
New York. Cited in: Northeim, C. M., and R. S. Truesdale. 1986.
Technical Guidance Document: Construction Quality Assurance for Hazar-
dous Waste Land Disposal Facilities. EPA 530-SW-86-031. OSWER Policy
Directive No. 9472.003. U.S. Environmental Protection Agency, Wash-
ington, D.C. 88 pp.
Dixon, W. J., and F. J. Massey. 1957. Introduction to Statistical Analysis.
McGraw-Hill Book Company, Inc. New York. Cited in: Northeim, C. M.,
and R. S. Truesdale. 1986. Technical Guidance Document: Construction
Quality Assurance for Hazardous Waste Land Disposal Facilities. EPA
530-SW-86-031. OSWER Policy Directive No. 9472.003. U.S. Environ-
mental Protection Agency, Washington, D.C. 88 pp.
Duncan, A. J. 1959. Quality Control and Industrial Statistics. Richard
D. Irwin, Inc. Homewood, IL. Cited in: Northeim, C. M., and R. S.
Truesdale. 1986. Technical Guidance Document: Construction Quality
Assurance for Hazardous Waste Land Disposal Facilities. EPA 530-SW-86-
031. OSWER Policy Directive No. 9472.003. U.S. Environmental Protec-
tion Agency, Washington, D.C. 88 pp.
Giroud, J. P. 1984. Geotextiles and Geomembranes, Geotextiles and Geo-
membranes 1. pp. 5-40.
Giroud, J. P., and J. E. Fluet, Jr. 1986. Quality Assurance of Ceosynthetic
Lining Systems. Geotextiles and Geomembranes 3(4):249-287.
Goldman, L. J., A. S. Damle, G. L. Kingsbury, C. M. Northeim, and R. S.
Truesdale. 1985. Design, Construction, and Evaluation of Clay Liners
for Hazardous Waste Facilities. EPA 530-SW-86-007F. U.S. Environmental
Protection Agency, Washington, D.C. 575 pp.
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Gordon, M. E., and P. N. Huebner. 1983. An Evaluation of the Performance
of Zone of Saturation Landfills in Wisconsin. Presented at the Sixth
Annual Madison Waste Conference, September 14-15, 1983. University of
Wisconsin. Cited in: Northeim, C. M., and R. S. Truesdale. 1986.
Technical Guidance Document: Construction Quality Assurance for Hazard-
ous Waste Land Disposal Facilities. EPA 530-SW-86-031. OSWER Policy
Directive No. 9472.003. U.S. Environmental Protection Agency, Washing-
ton, D.C. 88 pp.
Gordon, M. E., Huebner, P. M., and P. Kmet.
Performance of Four Clay-Lined Landfills
of the Seventh Annual Madison Waste Conference.
1984. An Evaluation of the
in Wisconsin. In: Proceedings
pp 399-460. Cited in:
Daniel, D. E. 1988. Construction of Clay Liners. In: Seminars--
Requirements for Hazardous Waste Landfill Design, Construction and
Closure. EPA CER1-88-33. U. S. Environmental Protection Agency,
Cincinnati, OH. (Note: Volume contains abbreviated lecture notes).
Grant, E. L. 1964. Statistical Quality Control. 3rd ed. McGraw-Hill
Book Company, Inc. New York. Cited in: Northeim, C. M., and R. S.
Truesdale. 1986. Technical Guidance Document: Construction Quality
Assurance for Hazardous Waste Land Disposal Facilities. EPA 530-SW-86-
031. OSWER Policy Directive No. 9472.003. U.S. Environmental Protec-
tion Agency, Washington, D.C. 88 pp.
Herzog, B. L., and W. J. Morse. 1984.
Field Determined Values of Hydraulic
pp. 30-52. In: Proceedings of the
University of Wisconsin-Extension,
Northeim, C. M., and R. S. Truesdale
ment: Construction Quality Assurance
Facilities. EPA 530-SW-86-031. OSWER Policy Directive No.
U.S. Environmental Protection Agency, Washington, D.C. 88 pp.
A Comparison of Laboratory and
Conductivity at a Disposal Site.
Seventh Annual Waste Conference,
Madison, Wisconsin. Cited in:
1986. Technical Guidance Docu-
for Hazardous Waste Land Disposal
9472.003.
Kish, L. 1967. Survey Sampling. John Wiley and Sons, Inc. New York.
Cited in: Northeim, C. M., and R. S. Truesdale. 1986. Technical
Guidance Document: Construction Quality Assurance for Hazardous Waste
Land Disposal Facilities. EPA 530-SW-86-031. OSWER Policy Directive
No. 9472.003. U.S. Environmental Protection Agency, Washington, D.C.
88 pp.
Knipschild, F. W., R. Taprogge, and H. Schneider. 1979. Quality Assurance
in Production and Installation of Large Area Sealing Sections of High-
Density Polyethylene. Materialprufung', Z\_ (11) :407-413.
Morrison, W. R., E. W. Gray, Jr., D. B. Paul, and R. K. Frobel. 1981.
Installation of Flexible Membrane Lining in fit. Elbert Forebay Reser-
voir. REC-ERC-82-2. U.S. Department of Interior, Bureau of Reclamation,
Denver, CO. p. 46.
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National Sanitation Foundation (NSF). 1985. Standard Number 54: Flexible
Membrane Liners. Rev. Standard. National Sanitation Foundation, Ann
Arbor, MI.
Northeim, C. M. and R. S. Truesdale. 1986. Technical Guidance Document:
Construction Quality Assurance for Hazardous Waste Land Disposal Facil-
ities. EPA 530-SW-86-031. OSWER Policy Directive No. 9472.003. U.S.
Environmental Protection Agency, Washington, D.C. 88 pp.
Spigolon, S. J., and M. F. Kelley. 1984. Geotechnical Assurance of Con-
struction of Disposal Facilities. Interagency Agreement No. AD-96-F-2-
A077. EPA 600/2-84-040. NTIS PB 84-155225. U.S. Environmental
Protection Agency, Cincinnati, OH.
U.S. Army. 1977. Construction Control for Earth and Rockfill Dams.
EM 1110-2-1911. Washington, D.C.
Wright, T. D., W. M. Held, J. R. Marsh, and L. R. Hovater. 1987. Manual of
Procedures and Criteria for Inspecting the Installation of Flexible
Membrane Liners in Hazardous Waste Facilities. EPA Contract No. 68-03-
3247. U.S. Enviornmental Protection Agency, Cincinnati, OH.
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CHAPTER 11
MANAGEMENT, MONITORING, AND MAINTENANCE
OF LINED WASTE STORAGE AND DISPOSAL UNITS
11.1 INTRODUCTION
Proper management of the operation of a lined waste containment unit is
necessary if the unit is to perform properly and the design criteria and the
maximum life of the liner system are to be realized. In managing lined
containment units it is necessary to:
- Protect the integrity of the containment unit and the lining system.
- Develop standard operating procedures and define them in an operations
and maintenance manual.
- Monitor the overall performance of the lining system to determine
whether it is operating within the design criteria and is not failing,
i.e. by monitoring the groundwater, the leachate collection and
removal system (LCRS) between the liners, etc.
- Inspect the condition of the liner to determine if any abnormal
swelling, degradation, or changes in properties have occurred.
- Inspect periodically other critical components of the containment
unit, e.g. the LCRSs, the embankments, etc.
The operational period of a containment unit can last less than 1 year
up to approximately 10 years. During this period, management focuses on the
following areas:
- Control of incoming wastes into the containment unit.
- Monitoring the performance of the liner system, its components,
and the earthworks, including the condition of the in-place liner.
- Maintaining and protecting the liner, the earthworks, and subsystems
such as the LCRSs.
- Training of personnel.
- Maintaining a logbook of incoming wastes, repair and maintenance
activities, etc.
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Following the operational period, a landfill is closed by placing a final
cover over the landfill in accordance with regulatory requirements, e.g. 40
CRF 264, Subpart G for the closure and post-closure of hazardous waste
containment units (EPA, 1986a). The maintenance of the landfill must con-
tinue during the construction of the final cover and through the post-closure
care period (PCCP), which lasts a minimum of 30 years. During this period,
the owner/operator must:
- Maintain the integrity and the effectiveness of the final cover,
including making repairs to the cap as necessary to correct the
effect of settling, subsidence, erosion, or other events.
- Continue to operate the LCRSs until no leachate is produced.
- Monitor the condition of the components of the liner system.
- Maintain and monitor the groundwater monitoring system.
- Maintain the vegetative cover and prevent run-on and runoff from
eroding or otherwise damaging the final cover.
- Protect and maintain surveyed bench marks.
- Continue to document maintenance, problems, and corrective measures
taken during the PCCP.
This chapter describes measures that need to be taken in managing
landfills and other containment units from the time operations commence
through the operational and post-closure care periods. These measures
include the standard operating procedures that must be developed at the time
the permit application is prepared. These operating procedures include
control of the incoming waste; monitoring the overall performance of the
waste containment unit; monitoring, maintaining, and repairing the components
of the lining system, including the LCRSs, the in-service liners, and the
earthworks; and maintenance of the final cover system.
11.2 STANDARD OPERATING PROCEDURES FOR A WASTE STORAGE AND
DISPOSAL UNIT
The three basic types of containment units are:
- Surface impoundments.
- Solid waste landfills.
- Waste piles.
Some standard operating procedures are applicable for all three types of
containment units; other procedures are specific to a single type. For
instance, all units designed and constructed with double liners will have
leak-detection systems between the two liners which must be monitored
11-2
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and maintained. Surface impoundments generally are storage units and are all
open to the atmosphere, though the top FML liner may or may not be exposed to
the weather depending on whether the liner is protected by a soil or other
type of cover. In the case of landfills, the liners will be buried for most
of their service lives.
Several standard handbooks and manuals are available on operating
MSW containment facilities (EPA, 1978; ASCE, 1976; EPA, 1973); however,
particularly in the case of lined containment units, additional information
should be incorporated in the standard operating procedures manual for the
specific facility. The additional requirements and procedures in an oper-
ating manual should reflect the specific types of materials that were used
and "as-built" construction details.
The operating and procedures manual for a specific unit should be
prepared by the design, construction, and operations team and should include,
as a minimum, the following:
- Operation and maintenance staff requirements and structure.
- Facility description and design parameters with "as-built" drawings.
- Response action plans, including emergency shutdown procedures.
- Operation variables and procedures, including methods of placing
materials into the unit and inspection schedules.
- Facility troubleshooting procedures.
- Preventive maintenance and requirements.
- Specialized maintenance and monitoring procedures, e.g. after a
storm.
- Plant personnel safety requirements and procedures.
- Equipment maintenance records.
- Site inspection records.
- List of permissible wastes.
- List of unacceptable wastes.
- Master file noting changes such as additions, revisions, or deletions
to procedures.
Certain operational procedures are not acceptable if the integrity of
the lined containment unit is to be maintained. These procedures include,
but are not limited to, the following:
- The discharge of high-temperature waste liquids onto exposed or
11-3
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unprotected FMLs, i.e. FMLs with no soil cover or with insufficient
standing liquid levels.
- The passage of any vehicle over any portion of an exposed FML.
- The discharge of incompatible wastes into the unit.
- The discharge of wastes directly onto an FML without adequate provi-
sion for energy dissipation, e.g. a splash pad, splash tubes, etc.
- Unauthorized modifications or repairs to the unit.
Preventing damage to the liner is extremely important since reliable repair
of a waste exposed FML, in almost all cases, is not feasible (Haxo, 1987).
Inasmuch as the technology for lining waste containment units is rela-
tively new and basic experience is limited, good records need to be kept of
the performance of a unit. Problems and difficulties as well as the results
of routine inspections should be noted.
11.3 INFORMATION ON DESIGN, CONSTRUCTION, AND MATERIALS OF CONSTRUCTION
Detailed information regarding all of the components of the liner system
should be available to the operating personnel during the operational period
and to caretaker personnel of a closed landfill during the PCCP. Availa-
bility of copies of the "as-built" drawings of the containment, detailed
information on the liner system, i.e. the FML and all components of the
leachate drainage, collection, and leak-detection systems, is particularly
important. This information should include data on the original character-
istics and properties of all components, and the reports of the compatibility
tests, e.g. those performed in accordance with Method 9090 (EPA, 1986b).
This information should be supplied by the designer of the unit as a package
from data he has developed in his investigation of the site and from data
furnished by the manufacturer of the liner, the installer, and the construc-
tion contractor. This information should include the data generated during
the implementation of the construction quality assurance plan, which is
discussed in Chapter 10.
Samples of the liner material and other components of the lining and
leachate collection and removal systems should be retained for possible
use in case the containment unit malfunctions. A full discussion should be
included in the package as to the compatibility limitations of the liner
material. The material was selected on the basis of its compatibility
with the wastes which it will contain; consequently, deviations in the waste
composition from the anticipated composition should be avoided. Information
of this type should be incorporated into the operating manual and into the
operator training program.
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11.4 CONTROL OF INCOMING WASTE
As indicated in the above section, the composition and character of the
waste needs to be controlled to avoid possible damage to the liner system.
Legal restrictions mandate that control must be maintained of the hazardous
materials placed in a containment unit to prevent improper disposal of a
waste. However, materials that are potentially aggressive to the lining
system also need to be controlled. Analyses should be performed on incoming
wastes to determine whether these wastes meet regulatory criteria for land
disposal or disposal at the particular containment unit and whether the
wastes contain constituents that may be aggressive to the lining mate-
rial. It should be noted that present EPA regulations require waste
generators to test their waste to determine whether it is restricted [40 CFR
268.7 (EPA, 1986c)]. However, as is discussed in Chapter 2, this testing may
not be sufficient for determining whether or not constituents that may be
aggressive to lining materials are present. Compatibility of the incoming
waste with the wastes already in the containment unit should also be assured.
The added waste may have a synergistic and damaging effect on the materials
of the liner system. Reference should be made to the analysis of the
leachate or waste liquid used in performing the compatibility tests during
the design and permitting stage. The operator should develop a knowledge of
the types of industries in the area to be aware of those materials that he
may be asked to dispose of.
According to current RCRA regulations [40 CFR 264.314 (1986 ed)],
wastes containing free liquids including those placed in drums, can no longer
be placed in a hazardous waste landfill. The absence of free liquids has to
be demonstrated by the "Paint Filter Liquids Test," EPA Method 9095 (EPA,
1986b). All free-standing liquid needs to be removed from the waste or
solidified and stabilized by soil, by a suitable dry absorbent, or by addi-
tion of selected chemicals before disposal in a hazardous waste landfill.
The effects of EPA regulations and current and future waste management
practices on the composition of wastes and waste liquid that are stored or
disposed of on land are discussed in Chapter 2.
In order to know the contents of a hazardous waste containment unit at
any given time, records need to be kept of the particular wastes placed in
the unit, as is required by EPA regulations [40 CFR 264, Subpart E (1986
ed.)]. In addition, the organic and inorganic constituents that are aggres-
sive toward liners should also be recorded, and significant amounts in the
landfill should be avoided.
The waste leachate or waste liquid should be analyzed periodically in
order to determine the current composition. Chemical reactions and vola-
tilization of the constituents within the unit will probably cause continual
change in the composition of the contained liquid in direct contact with the
lining system.
Adequate procedures for placing wastes in the unit should be incorpo-
rated in the design. Over-the-edge dumping of wastes should be avoided, as
should the addition of hot wastes, particularly liquids, directly on a
11-5
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liner. "Sacrificial" covers made of the same material as the liner have been
used on slopes to protect a liner from damage when wastes are dumped over the
edge. These covers can be inspected regularly and replaced when they have
deteriorated, but they must be replaced with a sheeting of the same composi-
tion as the liner or one that is known to be compatible with the liner.
For example, ingredients from one type of FML can migrate and damage a second
type with which it is in contact. Specially designed covers and troughs have
also been used for protecting the main liner during addition of waste to a
lined unit. Designs for placing liquid wastes in surface impoundments are
discussed in Chapter 7.
11.5 MONITORING THE PERFORMANCE OF THE WASTE CONTAINMENT UNIT
The principal purpose of a lined containment unit is to contain a
waste and control the escape of pollutants from the unit. The performance of
such a unit is measured by its ability to prevent uncontrolled migration of
waste constituents into the environment, particularly the groundwater.
Although performance monitoring for the lifetime of a containment unit is
relatively new and no method has been proven 100% effective in detecting
leaks, techniques are available that can increase confidence that a unit is
functioning as designed. These techniques range in complexity from ground-
water monitoring with monitoring wells to "high tech" geophysical systems
that can determine the point source of a leak.
Monitoring techniques can be divided into four types:
- Generalized leak-detection techniques based on observation of the leak
detection and drainage system constructed between the liners of
a double-liner system.
- Areal monitoring techniques which monitor the soil and groundwater in
the containment area.
- Point source leak-detection techniques which can detect a leak and
locate its source.
11.5.1 Leak Detection by a Secondary Leachate Collection
and Removal System (LCRSj
Present EPA regulations require an LCRS between the two liners of a
hazardous waste containment unit (40 CFR 264). This system, also known as
a secondary LCRS, is designed to intercept any liquids that may bypass the
top liner system and remove them for treatment and/or disposal. Thus, the
secondary LCRS monitors the performance of the top liner. Insofar as a
secondary LCRS not only detects leaks but collects and removes the liquids
present in the LCRS, it is also an integral part of the lining system as a
whole which is designed to control the migration of waste constituents. The
design of secondary LCRSs is discussed in Section 7.5.4.
In recently proposed regulations, the EPA proposes requiring the owner/
operator of a hazardous waste containment unit to develop site-specific
11-6
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response action plans (RAP) which establish operating procedures given a
rate of leakage through the top liner system (EPA, 1987a). The objectives of
the proposed regulations in combination with the double-liner design are:
- To detect leaks in the top liner at the earliest possible time.
- To contain the leakage within the engineered structure of the unit.
- To prevent groundwater contamination when technically feasible and
thereby obviate the need for corrective action.
The EPA considers a secondary LCRS the best available system for monitoring
the performance of a lined containment unit and for detecting and collecting
leakage through a top liner. An RAP goes into effect when a site-specific
action leakage rate (ALR) has been exceeded. The ALR constitutes a trigger
for initiating interaction between the owner/operator and the EPA. The ALR
is based primarily on leakage rate rather than leachate/waste liquid quality
because:
- Leakage rates allow for faster processing of data.
- Changes in rates of leakage are more indicative of progessive changes
in the condition of the top liner.
- Leakage rates are more indicative of the severity of a breach in the
FML.
The EPA has proposed an ALR of 5 to 20 gal per acre per day, which the EPA
believes is representative of a high level of CQA at a hazardous waste
containment unit. The EPA also proposes allowing an owner/operator to
develop a site-specific ALR value.
In the proposed regulations, RAPs are required for at least two leakage
rates:
- Rapid and extremely large leakage (RLL), which is defined as the
maximum design leakage rate that the secondary LCRS can remove under
gravity flow conditions.
- Leaks less than rapid and extremely large but greater than the ALR.
For leaks that exceed the ALR but are less than rapid and large, the EPA
considers acceptable responses to include:
- Terminating receipt of waste and closing the unit (or part of the
unit).
- Repairing any leaks expeditiously.
- Instituting operational changes to reduce leakage into the secondary
LCRS.
11-7
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- Increasing the pump capacity to allow more rapid collection and
removal of leachate, and, in addition, increasing groundwater moni-
toring.
- Maintaining current operating procedures (including the collection
and removal of leachate).
Different responses can be established for different bands of leakage rates.
The range of appropriate responses to rates greater than or equal to an RLL
rate can be the same as those in response to leakage rates less than RLL.
Appropriate responses include:
- Terminating receipt of waste and closing the unit.
- Repairing the leaks expeditiously, including possibly retrofitting
another liner on top of the existing system.
- Instituting operational changes to reduce leakage into the secondary
LCRS.
Elements of an RAP include:
- General description of unit.
- Description of waste constituents.
- Description of all events that may cause leakage.
- Discussion of factors affecting amounts of leakage entering LCRS.
- Design and operational mechanisms to prevent leakage of hazardous
constituents.
- Assessment of effectiveness of possible response actions.
11.5.2 Area! Techniques
11.5.2.1 Monitoring Wells —
By far the most common area! tool for monitoring a waste containment
unit is the monitoring well. This tool is considered by many to be indis-
pensable, since it ultimately provides "ground truth" as to the presence
of waste constituents in the groundwater. Typically, water samples are drawn
from the wells at some set interval and analyzed for the presence of con-
taminants. Construction details for a single well are presented in Figure
11-1. Multilevel well nests can be used to sample the groundwater flow at
several distinct levels, as is shown in Figure 11-2.
Monitoring wells have certain limitations, however. Placed in the
groundwater, a well does not reveal the presence of contaminants until they
have migrated from the unit through the underlying soil to the groundwater
itself; this process can take extensive periods of time, since groundwater
11-8
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moves very slowly. By the time contamination is detected, a significant
amount of damage may have occurred, which can mean that a significant amount
of cleanup is required, and potential liability has been incurred. Further-
more, the information resulting from a monitoring well only pertains to the
conditions of the groundwater that has contacted that particular well and may
not actually represent conditions even a few meters away. A schematic of the
limitations of a single monitoring well screened through a large vertical
section of a thick, uniform aquifer is presented in Figure 11-3. Ultimately,
the effectiveness of a groundwater monitoring plan is dependent on the
accuracy of the geohvdrologic studies performed during the site investigation
and design phases (see Section 7.4), together with assumptions about the
effects of locating the containment unit in the geohydrologic regime and
potential location of leaks in the lining system.
PVCCAP
x LOCKING STEEL CAP
CEMENT COLLAR
ife> / / GROUND SURFACE
5 FOOT LENGTH OF
6-INCH STEEL CASING
fc\ ^
'^t—^ CLEAN IMPERVIOUS BACKFILL
-.0: -y.
>•'• ?:<=
FLUSH THREADED SOLID
RISER PIPE..
4-INCH DIAM
0 0
WATER TABLE
BENTONITE BOREHOLE
oSEALANT O
CLEAN COARSE SAND
-
FLUSH-THREADED SLOTTED
WELL SCREEN,
BOTTOM OF BOREHOLE
BEDROCK
Figure 11-1.
Construction details for a sample monitoring well in which
the screen is located entirely within an unconsolidated
aquifer of sand and gravel. (Source: EPRI, 1985, p 5-28).
11-9
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:CLEAN IMPERVIOUS
'BACKFILL I..'-'-"
BENTONITE BOREHOLE
SEALANT ^ . t^.
CONFINING LAYER (AQUICLUDEI
Figure 11-2.
Multilevel sampling wells installed in individual, small-
diameter boreholes for monitoring groundwater quality in
three distinct aquifers. Well construction details are
presented in Figure 11-1. (Source: EPRI, 1985, p 5-33).
In designing a groundwater monitoring plan, an engineer must include
the following elements (Boutwell, 1988):
- The well system design, including the location of the wells, the depth
at which the wells are screened, the method of constructing the wells,
and the materials out of which the wells are to be constructed.
- A plan for sampling the wells and analyzing the samples.
11-10
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- A plan for
samples.
assessing the data from analyzing the monitoring well
Ideally, wells are located such that the concentrations resulting from a leak
anywhere in the lining system will be detectable at one or more monitoring
wells. A plan for placing the wells is developed using available equations
or computer models to optimize proximity to the regulated unit and proximity
to major flow path in order to achieve a minimum probability that a leak will
be detected. The depth of an individual well depends not only on the depth
of the aquifer to be monitored but also on the depth within the target
aquifer to be screened. The vertical placement of well screens should be
based on a calculated vertical distribution of the contaminants that poten-
tially may leak from the containment unit and appear in the aquifer at the
well site. Elements in the design of a single well are discussed in Section
7.5.7.8. Further discussion on the design and construction of monitoring
well systems, plans for sampling the wells and analyzing the well samples,
and methods of assessing data from monitoring wells can be found in Sanders
et al (1983), EPRI (1985), EPA (1986d), Barcelona et al (1987), U.S. Army
Toxic and Hazardous Materials Agency (1987), Nielsen (1987), and Keely and
Boateng (1987a and 1987b).
DISPOSAL FACILITY
SIMPLE STANDPIPE
WATER TABLE
VV.LEACHATE PLUME
GROUNDWATER FLOW
Figure 11-3.
Illustration showing a disadvantage of using a single monitor-
ing well screened through a large vertical section of a thick,
uniform aquifer. A water quality sample from this well would
not accurately represent concentration levels of contaminants
in the thin leachate plume due to dilution with uncontaminated
groundwater. (Source: Fetter, 1983, p 63).
Monitoring the soil gas and soil pore water in the unsaturated (or
vadose) zone is highly desirable because it can allow the detection of
contaminants, particularly volatile organic compounds in the case of soil
gas, prior to groundwater damage (Kirschner and Bloomsburg, 1988). One
device used to sample soil pore water is a suction or pressure-vacuum ly-
simeter which consists of a porous cup attached to tubing that runs to the
11-11
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soil surface. By creating a vacuum from the surface in the tubing, liquid
can be pulled from the surrounding soil through the porous cup and then
removed and analyzed (Figure 11-4). Like monitoring wells, lysimeters only
sample a very localized point, and the contaminant must intersect the ly-
simeter in order to be detected. One potential difficulty with lysimeters is
that they have been found to plug readily. Further information on monitoring
in the unsaturated zone can be found in Everett (1981), Wilson (1981, 1982,
and 1983), Marrin (1988), and Kerfoot (1988).
E
-------
two-coil electromagnetic induction apparatus. The transmitter coil induces
an electromagnetic field of known strength, and the receiving coil detects
distortions in the primary field resulting from a secondary field generated
by transmitting the primary field thorough an anomalous conducting body. Of
particular interest is the possibility that this technique can be used to
detect changes over time in the electrical conductivity of the soil pore
water resulting from an increase in the water content of the soil or changes
in the ionic content of the soil pore water, both of which could result from
the escape of constituents from a waste containment unit. The type of
instrument selected for use will depend on the range of subsurface depths of
interest.
TRANSMITTING COIL
RECEIVING COIL
ANOMALOUS
BODY
PRIMARY FIELD
SECONDARY FIELD
Figure 11-5.
Two-coi1
Griffiths
electromagnetic
and King, 1981)
induction apparatus. (Source:
Using a conductivity meter, or electromagnetic induction apparatus, one
or two operators walk the site taking conductivity readings over a previously
defined grid pattern. If liquids of higher or lower conductivity than the j_n_
situ pore water have entered the soil this will be indicated by a change in
conductivity values. A wide area can be profiled almost as fast as an
inspector can walk. Furthermore, with selection of correct instrumentation
it is possible to use one instrument to monitor the unsaturated zone and a
second instrument, designed for greater depths, to monitor the groundwater.
If questionable areas develop, one can decide to profile at deeper depths or
to zero in on a specific area more intensively with additional instrumenta-
tion. Griffiths and King (1981), Waller and Davis (1983), E.G. Jordan
(1984), and EPRI (1985), discuss this type of site surveying in detail.
11-13
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Ideally, electrical conductivity surveys of the site should be performed
prior to unit construction and again immediately after construction to
determine background levels. The site can then be surveyed every three to
six months to compare new data with the original background values. If
changes or trends develop in the unsaturated zone they can be watched and
investigated further.
At the present time, this type of survey probably offers the quickest
and least costly method available and provides the most readily interpretable
area! data. The effectiveness of this type of survey, however, depends on
certain site-specific conditions. If the site is highly conductive to begin
with (as most appear to be), large anomalies in conductivity will be neces-
sary before a leak will be detected.
11.5.3 Point Source Leak-Detection Techniques
So-called point source methods are techniques that can determine the
existence of a leak and zero-in on its location so that the leak can be
repaired. Two undergrid systems, one of which uses acoustical emission
monitoring (AEM) techniques and another which uses time-domain reflectometry
(TDR) techniques, and a pole-dipole electrical resistivity (ER) technique
have been evaluated (Waller and Singh, 1983; Shultz et al, 1984). The
undergrid systems must be designed and built into a site, and can potentially
be used with any type of liner. These systems cannot be retrofitted, except
possibly where an existing lining system is overlain by another liner. The
ER technique can be used in an existing site, but requires the insulating
properties of an FML in order to pinpoint the site of a leak.
AEM techniques have been successfully used to detect instabilities in
dams and slopes, retaining walls, footings, and underground mines, etc. by
detecting subaudible sound waves caused by the release of stored elastic-
strain energy in stressed materials. AEM has been suggested as a method of
detecting leaks based on that fact that transducers (e.g. microphones,
piezoelectric sensors) can be used to detect and monitor low frequency
vibrations caused by turbulent flow (velocity greater than 0.04 in. s )
through soil. Thus, AEM can be used to detect and monitor the sound of waste
liquid or leachate moving through drainage media or leaking from the contain-
ment unit (E. C. Jordan, 1984; Davis et al, 1984; Koerner et al 1984). A
schematic showing AEM equipment with a single sensor is presented in Figure
11-6, and a schematic showing the installation of an AEM sensor between the
two liners of a double-lined surface impoundment is presented in Figure
11-7. AEM as a technique for leak detection has had only limited field
testing. Potential drawbacks of AEM techniques for use in detecting leaks
include:
- Sensors and lead wires may corrode during the active life and the
post-closure care period of the unit.
- AEM may not detect small leaks or low velocity leaks where flow is
not turbulent.
11-14
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L.
A. Preamplifier
np (optional)
Sensor
Amplifier
and Adjustable
Bandpass Filter
Field Data
Display or
Recorder
FIELD EQUIPMENT
Electronic
Interpretation
Display or
Recording Device
._J I J
OPTIONAL SIGNAL INTERPRETATION
EQUIPMENT
Figure 11-6. Schematic of single channel AEM equipment. (Based on E. C.
Jordan, 1984, p 82).
FML
•^••.-.•-.••^^•^^^^^Waste Liquid ~-r-;-—;•;;;•;•"
~*^t^;-;-;-^; :::•••:::;;;;; ;;•"•;•;•;?! •;•"••"•"; •; ••;-:;;;
AEM Sensor Lead
to Surface
Soil Component of
Bottom Composite Liner'
Drainage Layer \ AEM Sensor
Collection Pipe
NOT TO SCALE
Figure 11-7.
Schematic showing installation of an AEM sensor below the
top liner in a double-lined surface impoundment. (Based on E.
C. Jordan, 1984, p 85).
11-15
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- AEM is sensitive to background noises,
machinery.
e.g. nearby equipment or
- The AEM system must detect a leak within a few minutes of occurrence
before the sound intensity diminishes to threshold values. Because of
this, continuous monitoring is required.
TDR techniques measure the electrical property variations in a material
along a pair of parallel transmission line conductors. Because TDR is
sensitive to soil moisture, it is attractive for leak detection. A con-
ceptual illustration of a TDR installation is presented in Figure 11-8.
Potential drawbacks of TDR techniques include:
- The wires must be installed in sand with a moisture content low enough
to provide an adequate contrast between unwetted and wetted sand.
- The wires may corrode.
- Although a drainage layer of well-compacted medium-to-fine grained
sand increases horizontal dispersion of a leak, thus increasing the
TDR response, too much fine sand rapidly attenuates the TDR signal and
is not desirable for drainage.
Hazardous Waste Landfill
Level
of Leachate
FML
Buried TDR Transmission
• Line Conductor Pairs
: Sand - Blanket
: Compacted Clay>
FML Component
of Bottom
Composite Liner
Figure 11-8.
Schematic of a TDR system installed at a hazardous waste
containment unit. (Based on E. C. Jordan, 1984).
11-16
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ER is a geophysical technique whereby an electrical current is intro-
duced into the ground by a pair of surface electrodes and the resultant
potential field is monitored by a second pair of electrodes. For the purpose
of leak detection, the current is passed from an electrode within a contain-
ment unit to an electrode outside the unit. When no leaks are present, a
voltage applied between the material contained in the unit and the earth
underneath the liner system produces a relatively uniform electrical poten-
tial distribution in the material contained in the unit. Leaks are located
by mapping any anomaly in the potential distribution caused by current
flowing through a leak (Shultz et al, 1984). The electrical leak location
method was successful in finding leaks in a full-scale impoundment that had
been fully tested using the vacuum box method (Darilek and Parra, 1988a and
1988b). A schematic of the electrical leak location method is shown in
Figure 11-9.
REMOTE
CURRENT
RETURN
ELECTRODE
CURRENT SOURCE
ELECTRODE
MOVING
MEASUREMENT
ELECTRODES
LIQUID
yxx x y
EARTH
MEMBRANE
UNER
CURRENT
FLOW LINES
Figure 11-9.
Schematic of the electrical resistivity testing technique
for detecting and locating leaks in an FML system. (Source:
Darilek and Parra, 1988a).
Even though the ER technique has had only limited field use to date, it
has shown promise particularly for locating leaks in surface impoundments
known to leak, for CQA during large-scale hydrostatic testing (which is
discussed in Section 10.4.5.4), and for CQA verification of certain portions
of an installed liner, such as the sump area.
to locate leaks in final cover systems for
being developed.
Methods of using the technique
landfills or impoundments are
EPRI
detail.
(1985) and E. C. Jordan (1984) discuss these techniques in more
11-17
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11.6 MONITORING THE COMPONENTS OF A LINING SYSTEM FOR A WASTE
CONTAINMENT UNIT AND RELATED MAINTENANCE ACTIVITIES
The lining system for a waste containment is made up of a number of
different components, each of which needs to function properly so that the
lining system as a whole can meet its performance requirements. In addition
to monitoring the overall performance of the lining system to determine
whether or not leaks have developed, the owner/operator needs to monitor the
condition of the different components of the system, insofar as such moni-
toring is possible. By monitoring these components, potential problems in
the lining system can be detected and corrected before constituents of the
contained materials are allowed to escape in an uncontrolled manner. Tech-
niques of monitoring the different components are discussed in the following
subsections.
11.6.1 Monitoring an In-Service Liner
Observing the in-service condition of a liner, particularly of an FML,
is desirable in order to determine whether exposure to the service environ-
ment has resulted in changes in properties that can significantly affect the
ability of the lining system to act as a barrier controlling the escape of
constituents from the containment unit. Of particular interest are the
combined effects of mechanical and chemical stresses.
The simplest method of monitoring an in-service FML is to visually
inspect the liner on a regular basis. Penetrations in the lining systems
(e.g. inflow/outflow pipes, etc.) and their connection with an FML in
particular should be inspected regularly since these areas are exposed to
complex mechanical stresses. Accessibility of the FML to observation is, of
course, a major difficulty in many situations, especially in the case of the
bottom liner of double-liner systems. In the case of a double-lined surface
impoundment without a soil cover on top of the top FML, the upper surface of
the top liner can be observed on the slopes during service and on the bottom
if the surface impoundment is drained. In the case of landfills and waste
piles, there is almost no accessibility to the lining system because of the
waste covering the FML.
To determine the actual effects of exposure on an FML-lined system, a
sample removed from the in-place liner should be tested for physical and
analytical properties. Analysis and fingerprinting of FMLs are discussed in
Section 4.2.2.6. Testing a sample removed from an in-place liner requires
cutting into the liner itself. In the case of an FML exposed to chemical
environments (e.g. a waste liquid), the resultant hole would be essentially
impossible to repair adequately by known techniques, i.e. the repair would
not meet the performance requirement of being equivalent to a newly installed
liner (Haxo, 1987).
A possible means of observing some of the effects of the waste liquid
on the FML and other components of the lining system during service is to
submerge coupons of the materials in the sump or in other locations in the
unit. Examples of coupon placement are shown in Figures 11-10 through 11-12.
11-18
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Pumped
Leachate -
Coupon
Figure 11-10. Schematic for a coupon in a landfill. (Based on
Tratnyek et al, 1985).
Pumped
Coupon
Figure 11-11. Schematic for a coupon in a waste pile. (Based on
Tratnyek et al, 1985).
Coupon
Coupon
Figure 11-12.
Schematic for coupon options in a surface impoundment.
(Based on Tratnyek et al, 1985).
11-19
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The use of coupons is briefly described in Chapter 5 for determining the
compatibility of an FML with the waste to be contained. Tratnyek et al
(1985) described a methodology for using removable coupons to monitor the
effect of exposure in a landfill by exposing samples of the FML and ancillary
materials of a lining system in a sump, or, in the case of a surface impound-
ment, on the slopes or floor of the unit. The samples can be withdrawn
periodically for visual inspection or physical and analytical testing. This
type of exposure, however, can only assess the chemical compatibility of the
materials with the leachate or waste liquid; it will not reflect the combined
chemical and mechanical stresses that are placed on the FML and the ancillary
materials during the actual exposure. Nevertheless, this type of test yields
results that can indicate which constituents in a waste stream are being
absorbed by the materials and potentially could affect performance of the
liner system. Combining such data with changes in mechanical properties will
be useful in assessing the rates of deterioration and in estimating the
long-term service life of an FML and the ancillary materials.
Coupons are being used by the Bureau of Reclamation to monitor (over a
5-year period) the performance of a fabric-reinforced FML that is lining the
Mt. Elbert Forebay Reservoir. Large coupons (20 x 100 ft) which incorporated
seams were placed on a 2-in. cushion of sand to separate them from the main
lining on the bottom of the reservoir. A soil cover was placed over the
coupons and was removed for retrieving and testing the coupons for changes in
physical properties and seam strengths (Frobel and Gray, 1984).
The difficulties involved in a coupon testing program are caused by
practical limitations, particularly if coupons are to be placed in a landfill
or waste pile sump. The institution of a coupon testing program needs to be
coordinated with the sump design during the design phase so that the coupons
do not interfere with pump operation, maintenance, and inspection. Retro-
fitted designs in which coupon samples are exposed to leachate after it has
been pumped from the sump can also be considered.
Surface impoundments holding wastewater may require cleaning to remove
sludges. Care must be taken during cleaning so as not to damage the liner.
Cleaning crews should be supervised by someone familiar with the liner to
ensure that punctures or tears are prevented, or patched if they occur.
However, in order to achieve a reliable bond between the patch and the liner,
the patching requires thorough cleaning and drying of the area to be patched.
If sludge is to be removed from the bottom of a wastewater impoundment, some
type of nonmechanical means should be used, e.g. a suction hose or dredging
head. This should minimize the potential for liner damage. Following
cleaning, the FML should be thoroughly inspected for possible distress
before liquid is introduced into the unit.
Any damage that is observed in an area of a surface impoundment liner
that is exposed to the weather should be repaired as quickly as possible in
order to avoid growth of the break. An opening on the slope could allow
rain water or liquid from the impoundment to get under the liner and could
result in a massive failure of the embankment on which the liner was placed.
Openings in the liner above the water line have resulted in major damage to
11-20
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the earthwork below. In these locations on the uncovered slopes, reliable
repairs can be made and maintained.
11.6.2 Monitoring, Maintenance, and Repair of Leachate
Collection and Removal Systems
LCRSs are required in landfills above the top liner and, in the case of
hazardous waste landfills, between the top and the bottom liners of a double-
liner system. The LCRS above the top liner is required to maintain a head of
leachate above the liner no greater than 1 foot. The LCRS between the top
and bottom liners functions as a potential leak-detection system which
requires rapid flow through the system to a sump area. In managing such a
landfill, the LCRSs must function over extended periods of time without
clogging, i.e. through the post-closure care period, which is at least 30
years. LCRS in waste piles and surface impoundments function similarly.
A variety of conditions can develop in an LCRS which would reduce the
flow. These conditions include mineralization, biological clogging, and in
the case of synthetic drainage systems, collapse of the polymeric components
due to the combined effects of softening (resulting from absorption of
organics from the leachate) and overburden pressure. Constant vigilance is
required as to the level of the leachate above the top liner in a landfill
and the appearance of leachate in the sumps. The pipes that are associated
with the LCRSs should be sufficiently large, e.g. 6-in. diameter, to allow
monitoring, maintenance, and potential repair.
At present, there is little direct experience with the maintenance of
LCRSs in waste containment units. (Bass, 1986) describes a variety of
mechanical, hydraulic, and chemical techniques borrowed from sewer technology
for maintaining and repairing of drainage pipes. These techniques were
devised for cleaning and removing debris from underground sewer pipes
and agricultural drainage systems. However, there are major constraints in
using these techniques in waste containment units including:
- Limited access to the pipes, i.e. risers are generally used instead of
manholes, and the manholes that are used are surrounded by waste.
- Potential damage to the pipes by mechanical cleaning. Because of
their chemical resistance, plastic pipes are used in collection
systems; these pipes are generally not as durable as metal or concrete
pipes with respect to mechanical cleaning operations.
In addition, there is the general problem of operator safety due to the
potentially hazardous nature of the leachate.
There are no demonstrated techniques for the maintenance and repair of
either synthetic or granular layers, although some chemical procedures for
cleaning have been suggested by Bass (1986).
11-21
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11.6.3 Monitoring the Gas-Venting System
The air gas vents installed near the crest or on the berm of a con-
tainment unit for releasing gas generated in or below a unit and for pre-
venting airlift should be inspected regularly and cleaned out, if neces-
sary, to avoid plugging. The same equipment used for inspecting and cleaning
LCRS pipes could be used for inspecting and cleaning the venting pipes.
Equipment that may find use in cleaning LCRS pipes is discussed by Bass
(1986).
11.6.4 Monitoring the Earthworks
The integrity of the embankments is essential to the proper performance
of surface impoundments and landfills. In the case of surface impoundments,
regular inspections should be made of the embankments and berms. Attention
should be given to possible ground movements, cracks, and erosions of the
earth. Since an erosion control problem usually exists when earth is exposed
on an embankment slope, preventive measures should be taken in the design.
However, the inspection is still needed because failure of the earthwork can
result in failure of the liner.
The condition of the soil in the dikes can be monitored through the use
of piezometers and observation wells installed on the outside of the embank-
ments to measure seepage of water or leachate into the embankments. This
procedure is being followed at the Mt. Elbert Forebay Reservoir to measure
the groundwater level within the embankment at the end of the reservoir
(Frobel and Gray, 1984). Prior to the installment of the FML liner which
replaced a clay liner, the piezometers had indicated a higher than anti-
cipated groundwater level in the dam of the reservoir, which was lined at
that time with a clay. After lining the reservoir with an FML, the water
level rose in the observation wells in response to the initial filling; the
water level levelled off and later dropped, indicating reduced seepage from
the reservoir. In addition, tests were run with inclinometers along the face
of the reservoir, and observations were made on the inside of the reservoir.
11.6.5 Vegetation Control
Growth of vegetation inside and around a containment unit must be
controlled to prevent damage to the liner from the anchor trench down the
side slope. Damage can result if weed growth begins under an FML or, if a
soil cover is present, on top of the liner. In the latter case, roots of
plants might penetrate the FML creating a hole which, once opened, can
increase in size. However, no such type of failure by roots has been re-
ported, as roots tend to grow laterally on an FML surface. Ideally, the berm
area around the impoundment should be treated with weed killer initially, and
maintained in a weed-free condition.
11-22
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11.6.6 Rodent Control
Rodents, such as gophers, squirrels, rats, muskrats, and mice, have been
reported to have caused severe damage to the soil embankments of lined waste
containment units. These animals can honeycomb an embankment and may pos-
sibly damage a liner if the liner blocks the path to food or water. Rodents,
particularly certain ground squirrels, have also been known to eat some PVC
material. The presence of these animals at the construction site should be
assessed during the design phase. Provisions to control their impact
can then be made and incorporated into both the design and the maintenance
procedures for the facility. Any holes in the earthworks dug by burrowing
animals should be filled in as soon as possible even if the animal leaves the
site.
11.6.7 Monitoring of Diversion Drainage System
If a diversion drainage system is set up around the unit to prevent
water from entering the unit, it should be inspected periodically to ensure
that the system is still capable of managing the design capacity, e.g. the
water volume resulting from a 24-hour, 25-year storm.
11.6.8 Monitoring to Prevent Vandalism and Unauthorized Dumping
The site must be carefully monitored to prevent vandalism and unau-
thorized dumping of wastes. These may be curtailed by limiting vehicular
access to the disposal site, locating the site out of general view, and by
fencing in ponds and similar impoundments.
11.7 MAINTENANCE OF THE FINAL COVER
At the end of the operational period for a landfill, a final cover is
constructed over the fill. The purpose of the cover is to minimize leachate
formation within the landfill by preventing surface water from infiltrating
the fill throughout and beyond the post-closure care period. The final cover
system also controls the venting of gases that may be generated within the
fill and isolates the wastes from the surface environment. The final cover
system is designed and constructed so that it functions with minimum main-
tenance, promotes drainage, minimizes erosion, accommodates settlement and
subsidence, and has a permeability less or equal to that of the bottom liner
system. Lutton (1986) and McAneny et al (1986) discuss the design, construc-
tion, and maintenance of cover systems in more detail. See also Chapter 7
(Section 7.5.8) and EPA 1987b for additional information on final covers.
As set forth in RCRA guidance, the final cover is a multi-layer struc-
ture consisting of soil layers of different types and probably an FML con-
structed on a mass of waste that can settle unevenly. As such, the final
cover is potentially subject to a variety of problems which are listed in
Table 11-1.
11-23
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TABLE 11-1. POTENTIAL PROBLEMS WITH FINAL COVER SYSTEMS
Chronic erosion Chronic vegetation failure
Erosion event Vegetation failure event
Inadequate drainage system Frost disturbance
Slope creeping Wind erosion
Slope sliding Cracking
Subsidence Plugging of porous soil
Differential settlement Deterioration of synthetics
Flooding Loss of locations and monuments
Burrowing animals Root penetration
Based on Lutton, 1986, p 133.
A program of maintenance and repair suggested by Lutton (1986), consists
of the following measures:
- Periodic grooming of the vegetative cover, such as the one described
by Conover (1977), to maintain the vegetation and recondition the
soi 1.
- A program of repairs to deal with the development of gullies, subsi-
dence of the cover, slope instability, defective drainage systems, and
leakage spots through which there can be an upward flow of gas or
capillary water which could be toxic to plant growth.
- Reconstruction of major damage.
Lutton (1986) also suggests that the maintenance program concentrate its
effort in the early years to ensure that long-range problems can be recog-
nized and corrective actions taken.
The principal objective in managing the cover system is to maintain the
effectiveness of the final cover. Management of the final cover begins
essentially with the completion of cover construction and the planting of the
vegetative cover and extends a minimum of an additional 30 years. Management
entails regular inspections of all of the components, with particular atten-
tion to the drainage system which must be able to control the run-on and
run-off equivalent to a 24-hour, 25-year storm. The surface drainage system
must be maintained to prevent any intrusion of surface water into the land-
fill. Maintenance of the vegetative cover and the gas-venting systems is
also of critical importance. The vegetative cover is important in preventing
erosion, and the gas-venting system is necessary to prevent a gas buildup
from forming inside the closed landfill. Continuous observation must
be made to detect any settlement and subsidence of the cover, which must be
corrected to prevent depressions in the cover through which surface water may
pool and enter the landfill.
11-24
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11.8 REFERENCES
ASCE, Solid Waste Management Committee. 1976. Sanitary Landfill. Manuals
and Reports on Engineering Practice No. 39. American Society of
Civil Engineers, New York, NY.
Barcelona, M., J. F. Keely, W. A. Pettyjohn, and A. Wehrmann. 1987.
Handbook: Groundwater. EPA 625/6-87/016. U.S. Environmental Protection
Agency, Ada, OK. 212 pp.
Bass, J. 1986. Avoiding Failure of Leachate Collection and Cap Drainage
Systems. EPA 600/2-86-058 (NTIS No. 86-208 733). U.S. Environmental
Protection Agency, Cincinnati, OH.
Boutwell, G. P. 1988. Personal communication. Soils Testing Engineers,
Baton Rouge, LA.
Conover, H. S. 1977. Ground Maintenance Handbook. 3rd edition. McGraw-
Hill, NY. Cited in: Lutton, R. J. 1986. Design, Construction, and
Maintenance of Cover Systems for Hazardous Waste—An Engineering
Guidance Document. U.S. Environmental Protection Agency, Cincinnati,
OH. 183 pp.
Darilek, G. T., and J. 0. Parra. 1988a. The Electrical Leak Location Method
for Geomembrane Liners. In: Land Disposal, Remedial Action, Inciner-
ation and Treatment of Hazardous Waste, Proceedings of the Fourteenth
Annual Solid Waste Research Symposium. U.S. Environmental Protection
Agency, Cincinnati, OH. (In press).
Darilek, G. T., and J. 0. Parra. 1988b. The Electrical Leak Location Method
for Geomembrane Liners: Final Technical Report. EPA Contract No. CR-
811771-01-3. U.S. Environmental Protection Agency, Cincinnati, OH.
Davis, J. L., M. J. Waller, B. G. Stegman, and R. Singh. 1983. Evaluations
of Time-Domain Reflectometry and Acoustic Emission Techniques to Detect
and Locate Leaks in Waste Pond Liners. In: Land Disposal of Hazardous
Waste, Proceedings of the Ninth Annual Research Symposium. D. W.
Shultz, ed. EPA 600/9-83-018. U.S. Environmental Protection Agency,
Cincinnati, OH. pp 186-202.
E. C. Jordan Co. 1984. Performance Standard for Evaluating Leak Detec-
tion, Draft - Final Report. Contract No. 68-01-6871. U.S. Environ-
mental Protection Agency. Washington, D.C.
EPA. 1973. Training Sanitary Landfill Employees. SW-43c.l. U.S. Environ-
mental Protection Agency, Washington, D.C. 203 pp.
EPA. 1978. Process Design Manual - Municipal Sludge Landfills. EPA-625/
1-78-010. SW-705. U.S. Environmental Protection Agency, Washington,
D.C. 269 pp.
11-25
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EPA. 1985. Minimum Technology Guidance on Double Liner Systems for Land-
fills, Surface Impoundments, and Waste Piles—Design, Construction
and Operation. Draft. EPA/530-SW-85-014. U.S. Environmental Pro-
tection Agency, Washington, D.C. 71 pp.
EPA. 1986a. Standards for Owners and Operators of Hazardous Waste Treat-
ment, Storage, and Disposal Facilities, Subpart G--Closure and Post-
Closure. 40 CFR 264.110-264.120. National Archives and Records
Administration, Washington, D.C.
EPA. 1986b. EPA Test Methods for Evaluating Solid Waste. Vol. 1: Labor-
atory Manual, Physical/Chemical Methods. 3rd ed. SW-846. U.S.
Environmental Protection Agency, Washington, D.C. September 30, 1986:
Method 9090. "Compatibility Test for Wastes and Membrane Liners."
Method 9095. "Paint Filter Liquids Test."
EPA. 1986c. Hazardous Waste Management Systems; Land Disposal Restrictions.
Final Rule. Federal Register 51(216):40572-40654. (Appropriate changes
in 40 CFR 260-262, 264, 265, 268, 270, and 271 as of 1987 ed.).
EPA. 1986d. RCRA. Ground-Water Monitoring Technical Enforcement Guidance
Document (TEGD). OSWER-9950.1. U.S. Environmental Protection Agency,
Washington, D.C.
EPA. 1987a. Liners and Leak Detection for Hazardous Waste Land Disposal
Units; Notice of Proposed Rule Making. Federal Register 52(103):
20218-20311.
EPA. 1987b. Minimum Technology Guidance on Final Covers for Landfills and
Surface Impoundments. Draft. EPA Contract No. 68-03-3243, Work Assign-
ment No. 2-14. U.S. Enivronmental Protection Agency, Washington, D.C.
31 pp.
EPRI. 1985. Groundwater Manual for the Electric Utility Industry. EPRI
CS-3901, Vol. 3. Electric Power Research Institute, Palo Alto, CA.
Everett, L. G. 1981. Monitoring in the Vadose Zone. Ground Water Monitor-
ing Review 1(2):44-51.
Fetter, C. W. 1983. Potential Sources of Contamination in Ground Water
Monitoring. Ground Water Monitoring Review 3(2):60-64. Cited in: EPRI.
1985. Groundwater Manual for the Electric Utility Industry. EPRI
CS-3901, Vol. 3. Electric Power Research Institute, Palo Alto, CA.
Frobel, R. K., and E. W. Gray. 1984. Performance of the Fabric-Reinforced
Geomembrane at Mt. Elbert Forebay Reservoir. In: Proceedings of the
International Conference on Geomembranes, June 20-24, 1984, Denver, CO.
Vol. II. Industrial Fabrics Association International, St. Paul,
MI. pp 421-26.
11-26
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Griffiths, D. H. and F. F. King. 1981. Applied Geophysics for Engineers and
Geologists: The Elements of Geophysical Prospecting. 2nd ed. Oxford
Pergamon Press, Elmsford, NY. 230 pp. Cited in: EPRI. 1985. Ground-
water Manual for the Electric Utility Industry. EPRI CS-3901, Vol. 3.
Electric Power Research Institute, Palo Alto, CA.
Haxo, H. E. 1987. Assessment of Techniques for In Situ Repair of Flexible
Membrane Liners: Final Report. EPA/600/2-87-038 (NTIS No. PB 87-191-
813). U.S. Environmental Protection Agency, Cincinnati, OH. 61 pp.
Keely, J. F., and K. Boateng. 1987a. Monitoring Well Installation, Purging,
and Sampling Techniques—Part 1: Conceptualizations. Ground Water
25(3):300-313.
Keely, J. F., and K. Boateng. 1987b. Monitoring Well Installation, Purging,
and Sampling Techniques—Part 2: Case Histories. Ground Water 25(4):
427-439.
Kerfoot, H. B. 1988. Is Soil-Gas Analysis an Effective Means of Tracking
Contaminant Plumes in Ground Water? What Are the Limitations of the
Technology Currently Employed? Ground Water Monitoring Review 8(2):
54-57.
Kirschner, F. E., Jr., and G. L. Bloomsburg. 1988. Vadose Zone Monitoring:
An Early Warning System. Ground Water Monitoring Review 8(2):49-50.
Koerner, R. M., A. E. Lord, and V. A. Luciani. 1984. A Detection and
Monitoring Technique for Location of Geomembrane Leaks. In: Proceedings
of the International Conference on Geomembranes, June 20-24, 1984,
Denver, CO. Vol II. Industrial Fabrics Association International, St.
Paul, MN. pp 379-384.
Lutton, R. J. 1986. Design, Construction, and Maintenance of Cover Systems
for Hazardous Waste—An Engineering Guidance Document. U.S. Environ-
mental Protection Agency, Cincinnati, OH. 183 pp.
Marrin, D. L. 1988. Soil-Gas Sampling and Misinterpretation. Ground
Water Monitoring Review 8(2):51-54.
McAneny, C. C., P. G. Tucker, J. M. Morgan, C. R. Lee, M. F. Kelley, and R.
C. Horz. 1985. Covers for Uncontrolled Hazardous Waste Sites. EPA
540/2-85/002. U.S. Environmental Protection Agency, Cincinnati, OH.
554 pp.
Nielsen, D. M. 1987. Common Problems Associated with the Design and Instal-
lation of Groundwater Monitoring Wells. In: Proceedings of the National
Conference on Hazardous Wastes and Hazardous Materials, March 16-18,
1987, Washington, D.C. Hazardous Materials Control Research Institute,
Silver Spring, MD. pp 178-184. (Note: This is an edited version of a
monograph to be published by the Hazardous Materials Control Research
Institute).
11-27
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Northeim, C. M., and R. S. Truesdale. 1986. Technical Guidance Document:
Construction Quality Assurance for Hazardous Waste Land Disposal Facil-
ities. EPA 530-SW-86-031. OSWER Policy Directive No. 9472.003. U.S.
Environmental Protection Agency, Washington, D.C. pp 47-53.
Sanders, T. G., R. C. Ward, T. C. Loftis, T. D. Steele, D. D. Adrian, and V.
Yevjevich. 1983. Design of Networks for Monitoring Water Quality.
Water Resources Publications, Littleton, CO.
Shultz, D. W., B. M. Duff, and W. R. Peters. 1984. Performance of an
Electrical Resistivity Technique for Detecting and Locating Geomembrane
Failure. In: Proceedings of the International Conference on Geomem-
branes, June 20-24, 1984, Denver, CO. Volume II. Industrial Fabrics
Association International, St. Paul, MI. pp 445-49.
Tratnyek, J. P., J. M. Bass, W. J. Lyman, P. P. Costas, and C. J. Jantz.
1985. Proposal Methodology for Removable Coupons Testing. Contract No.
68-02-3968. Task Assignment No. 36. U.S. Environmental Protection
Agency, Washington, D.C.
U.S. Army Toxic and Hazardous Materials Agency (USATHAMA). 1987. Geo-
technical Requirements for Drilling, Monitoring Wells, Data Acqui-
sitions, and Reports. Department of the Army, Aberdeen Proving Ground,
MD. 65 pp.
Waller, M. J., and J. L. Davis. 1983. Assessment of Innovative Techniques
to Detect Waste Impoundment Liner Failures. Final Report. Contract No.
68-03-3029. U.S. Environmental Protectional Agency, Cincinnati, OH.
Waller, M. J., and R. J. Singh. 1983. Leak-Detection Techniques and
Repairability for Lined Waste Impoundment Sites. In: Proceedings of
Management of Uncontained Hazardous Waste Sites, Washington, D.C.
Hazardous Materials Control Research Institute, Silver Spring, MD.
pp 147-153.
Wilson, L. G. 1981. Monitoring in the Vadose Zone, Part I. Ground Water
Monitoring Review 1(3):32-41.
Wilson, L. G. 1982. Monitoring in the Vadose Zone, Part II. Ground Water
Monitoring Review 2(l):31-42.
Wilson, L. G. 1983. Monitoring in the Vadose Zone, Part III. Ground Water
Monitoring Review 3(1):155-166.
Woods, W. W. 1973. A Technique Using Porous Cups for Water Sampling at Any
Depth in the Unsaturated Zone. Water Resources Research 9(2):486-88.
Cited in: EPRI. 1985. Groundwater Manual for the Electric Utility
Industry. EPRI CS-3901, Vol. 3. Electric Power Research Institute,
Palo Alto, CA.
11-28
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CHAPTER 12
COSTS ASSOCIATED WITH MATERIALS AND CONSTRUCTION
OF WASTE STORAGE AND DISPOSAL UNITS
12.1 INTRODUCTION
If, after chemical compatibility and performance requirements have been
considered, it appears that a number of different FMLs and ancillary ma-
terials can be used in the construction of a particular storage or disposal
unit, then cost may become an important factor in the ultimate design of the
liner system and in the selection of materials. Although the costs of these
materials are only part of the overall construction cost of such a unit, they
can significantly affect the overall cost. Consequently, costs will be
considered by designers and engineers in selecting specific materials for use
in construction.
This chapter discusses factors influencing the cost of constructing a
waste containment unit and discusses the cost of various liner materials as
well as other construction materials such as pipes, geogrids, geonets,
drainage materials, etc. Some costs for earthworks construction and factors
that can affect liner installation costs are presented. The cost of dif-
ferent storage or disposal alternatives are compared, and lastly, costs for
quality assurance inspection of the materials and the construction are
discussed.
12.2 FACTORS AFFECTING COSTS OF WASTE CONTAINMENT UNITS
A wide range of factors are involved in the total cost of the design and
construction of waste containment units:
- The types of materials required by the design. Costs of the FML and
the other polymeric components of the liner system are largely
determined by the prices of the resins necessary to their manufacture.
A choice between some materials, e.g. drainage materials, may be made
on a cost-benefit basis.
- The location of the facility and the transportation costs involved
in bringing the lining material or fill to the site. Liner projects
in remote areas with rugged terrain will have higher costs than those
at sites with more favorable topography and geology or those located
nearer to the source of liner materials.
12-1
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- As with most construction activities, the time of the year and its
effect on labor availability and productivity. In addition, inclement
weather can disrupt liner installation. In the case of FMLs, success-
ful field seaming requires a fairly narrow range of environmental
conditions; they cannot be placed in excessive heat or cold, snow or
rain, or on nonstable or wet ground. Delays in construction and liner
placement can thus result. Adverse weather conditions can affect the
placement of other construction materials as well.
- The size of the disposal facility unit. Size can significantly affect
the cost per unit area of liner. As with most projects and construc-
tion materials, the larger the project, the lower the unit cost of
work productivity and materials. Large liner projects usually have
significant economies of scale.
- Type of soil on site. In the construction of hazardous waste disposal
units, soil materials are needed for construction of the soil compo-
nent of a composite liner, the embankments, and, if called for in the
design, the soil protective cover above the top liner. In addition,
granular materials may be used in the leachate collection systems.
The availability or lack of availability of soil materials on the site
that are adequate for use in constructing the unit will significantly
affect cost.
- Type of FML selected. Differences in FML properties can have a small
effect on the cost of site preparation and installation, particularly
if the selected FML requires a relatively small particle size bedding.
In addition, the type of FML selected may make it necessary to apply a
herbicide to the bedding surface to alleviate concern about plant
growth that might lead to puncture of an overlying installed FML.
- Differences in FML installation costs. Some materials will require
more work effort and quality control than others, particularly in the
field seaming of the sheeting or panels into the final liner. How-
ever, final installed costs quoted for the FMLs will take these
differences into account.
- The quality control and quality assurance that is needed at all
stages of construction and liner installation. The risk of a contain-
ment failure with its potentially high liability makes it essential
that all specifications are met.
The basic design assumptions, both economic and technical, must be
established before a detailed cost estimate can be prepared for any system.
Potential cost elements of a waste containment unit are listed in Table
12-1. All technical design assumptions should be stated in making the
cost estimate for constructing the unit. These assumptions include:
- The anticipated operating life of the disposal facility.
- The annual waste storage or disposal requirement.
12-2
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TABLE 12-1. POTENTIAL COST ELEMENTS
OF A WASTE CONTAINMENT UNIT3
Geotechnical investigation of site
Clearing and grubbing
Excavation volume
Grading and compaction
Berm embankment construction
Compatibility testing of the component materials
Soil component of bottom liner
FML component of composite bottom liner
Components of a secondary leachate
collection system:
Drainage layer (synthetic or granular)
Filter layer
Protective soil layer
Geotextile support layer
Leachate collection pipes
FML top liner
Components of a primary leachate collec-
tion system (if unit is a landfill or
a waste pile)
Soil cover above top liner
Auxiliary cleanouts
Pump
Sump
Diversion ditch
Riprap
Quality control and quality assurance
aMany of these cost elements can be divided
into material costs and installation/con-
struction costs.
Based on Sai and Zabcik, 1985.
12-3
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- Type of constructed unit, i.e., whether the unit is constructed above
or below grade or a combination of the two.
- Design of liner system including top liner, bottom liner (if double-
lined), leachate collection system, and leak-detection system.
- Site-specific requirements based on size of the unit. For example, if
the unit to be constructed is a surface impoundment, these require-
ments will include depth, freeboard zone, berm width, and height of
embankments.
Once the basic design assumptions for a particular unit are finalized, it is
possible to estimate the cost of materials and construction.
12.3 LINER SYSTEM COMPONENT COSTS
12.3.1 Factors Influencing Component Costs
Except for the soil and sand/gravel components of the lining system
for a hazardous waste storage or disposal unit, the components of the system
are made from polymeric materials as is described in Chapter 4. These
components can incluse FMLs, geotextiles, synthetic drainage materials,
geogrids, and pipe. As the costs involved in manufacturing these polymeric
components are relatively moderate, their price is largely determined by
the prices of the raw materials necessary to their manufacture.
As the industry that produces the polymeric components of a lining
system is a minor segment of the polymer industry, raw material costs are set
by producers of polymers and other ingredients of the component compound.
Because the polymers themselves are made from chemicals from petroleum
sources, costs ultimately depend on the cost of natural gas or crude oil
feedstocks. Increases in the price of these commodities throughout the 1970s
resulted in a corresponding rise in polymer costs.
In the 1980s, the costs of natural gas and crude oil feedstocks have
stabilized considerably, and this has contributed to the stabilization of
monomer prices and, consequently, polymer prices.
12.3.2 Flexible Membrane Liners
Prices for flexible membrane liners (FMLs) are quoted in a variety of
ways:
- As "rolled goods" or sheeting as produced by liner manufacturers.
- As "fabricated liners," e.g. the price of membranes produced by the
factory seaming of sheeting into large panels which are then sold to
installers.
- As "final installed costs" which include the cost of installing the
FML at the site.
12-4
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Due to the structure of the industry, the prices of some liners are quoted in
all three ways. When the liner manufacture, fabrication, and installation
are performed by a single company, only a single price may be quoted, i.e.
installed costs.
Table 12-2 provides cost data for selected liner materials based on
estimates provided by various manufacturers, fabricators, and installers
of the specific materials. Costs are per square foot of liner material,
installed in quantities sufficient to line a 100,000 ft2 unit with a single
liner. Costs presented do not include costs for site and surface prepara-
tion, engineering design, or soil cover. Costs will be affected by transport
distance, size of project, time of year, local labor, and complexity of the
installation. The unit costs shown do not represent the total cost of a
liner system, since other components, such as leachate collection and leak-
detection systems, may be required. Also, the costs presented do not reflect
equal service life or performance of the liners. Since all liners for
landfills are covered, the additional cost of the soil cover will not affect
the choice of the liner. However, in the case of surface impoundments, some
lining materials need to be covered to protect them from ultra-violet light,
wind, and sunlight; this additional cost is not reflected in Table 12-2.
12.3.3 Geotextiles
Geotextiles vary considerably in construction and can have a variety
of uses in the liner system design of waste containment units. They can
be used to reinforce embankment slopes, to protect FMLs against puncture,
and as a filter medium in leachate collection systems. The use of geo-
textiles in waste containment is discussed in Section 4.2.3.
Generally, geotextile manufacturers use many distributors. As in the
case of liner materials, economies of scale are realized for large instal-
lations versus smaller ones. Table 12-3 lists estimated costs for a variety
of geotextile materials based on a 1-sq acre containment unit (44,000 ft2);
these costs do not include shipping and installation, which will vary
from $0.04 to $0.07 per sq ft.
12.3.4 Drainage Materials
Synthetic and granular drainage media can be used in leachate collection
systems. Various types of synthetic drainage materials have recently been
introduced commercially. However, even though these synthetic media have
many potential advantages over granular media, they are still unproven for
long-term application. Geonets are grid-like polymeric products used as
in-plane drainage systems which must be used in conjunction with geotextiles,
FMLs, or other materials on their upper and lower surfaces. The geonets and
their use as a drainage medium are described in Section 4.2.5. Also a number
of examples of their use in designing of LCRSs are presented in Chapter 7,
e.g. Section 7.5.4.2.2. The cost of these materials range from $0.15 to
$0.45 per ft2 depending on the specific product.
12-5
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TABLE 12-2. INSTALLED 1987 COSTS3 FOR FLEXIBLE MEMBRANE LINERS
Material
Thickness, Type of polyester
mil fabric^ reinforcement
Cost/sq ft,
$
CPE
30
36
45
10 x 10 - 1,000 d
10 x 10 - 1,000 d
0.45-0.50
0.55-0.65
0.65-0.70
CSPE
30
36
45
45
60
8 x 8 - 250 d
10 x 10 - 1,000 d
8 x 8 - 250 d (2)
10 x 10 - 1,000 d
10 x 10 - 1,000 d
0.62-0.65
0.65-0.70
0.85-0.90
0.72-0.78
1.10-1.20
HOPE and LLDPE
40
60
80
100
0.40-0.50
0.55-0.65
0.65-0.75
0.75-0.90
PVC
30
40
50
60
0.27-0.30
0.32-0.35
0.40-0.45
0.50-0.55
PVC-OR
30
40
0.40-0.45
0.47-0.52
Nitrile rubber/PVC alloy
30
8 x 8 - 250 d
0.70-0.75
Ethylene interpolymer
alloy
30
6.5 oz/yd2
0.70-0.75
aCosts are estimates for an installed FML liner covering for
100,000 ft2. Variables that can affect costs are transport fees,
labor, time of year, and complexity of site.
bd = Denier; oz = ounces. Number in parentheses represents the number
of plies of reinforcing fabric.
12-6
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TABLE 12-3. GEOTEXTILE COSTS
Material
Nonwoven polypropylene
Nonwoven polypropylene
Nonwoven polypropylene
Nonwoven polypropylene
Woven polypropylene
Nonwoven polyester
Nonwoven polyester
Nonwoven polyester
Nonwoven polyester
Thickness,
mi 1
40
50
90
150
25
85
100
150
210
Cost/sq fta,
$
0.05
0.06-0.08
0.10-0.14
0.23-0.26
0.06-0.09
0.06-0.09
0.10-0.12
0.20-0.21
0.23-0.32
aPrices are based on approximately 44,000 sq ft of
material and do not include shipping and instal-
lation, which will vary from 4 to 7£ sq ft. Prices
for individual geotextiles will also vary from
distributor to distributor.
Source: Sai and Zabcik, 1985.
Geocomposites are a wide range of composite materials which consist of
two or more geosynthetics and which are designed to fulfill various functions
(see Section 4.2.6). Table 12-4 lists costs of various types of drainage
geocomposites by square footage, as well as cost reductions for quantity
purchases.
Costs for granular media will be highly site specific and dependent on
transport distance, as are all earthen materials. Costs for sand and gravel
are presented in Table 12-5.
12.3.5 Geogrids
Geogrids are being used as soil stabilization and reinforcement in the
construction of embankments and dikes, as is discussed in Section 4.2.4.
They can be used in constructing containment units to steepen earth slopes or
to create earth embankments used in subdividing individual units within a
disposal facility. As is discussed in Chapters 4 and 7, a large variety of
these materials of different structures, compositions, and strengths are
12-7
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TABLE 12-4. COSTS OF GEOCOMPOSITE DRAINAGE MATS
INi
I
CO
Configuration
Core material
Nylon
Nylon
Polystyrene
Expanded:
polystyrene
beads bound
by bitumen
Polystyrene/
polyethylene
Polyethylene
Outer
geotextile filter
Nonwoven-needled
Nonwoven-needled
Nonwoven-heat set
or needled
Nonwoven-needl ed
Nonwoven-heat set
Nonwoven-needled
Overall Shape
thickness of core
0.4 in. Monofi lament
web
0.8 in. Monofi lament
web
0.75 in. "Egg-carton"
Up to 2 ft Bound beads
5/16 in. Corrugated
ribs
1.0 in. Cylinders
Maximum stress
27 psi
27 psi
30 psi
Virtually
unlimited
(compressible)
• • •
230 psi
1985
unit costa
$0.56/ft2
$0.53/ft2
(quantity)
$1.12/ft2
$1.07/ft2
(quantity)
$1.15/ft2
$0.76/ft2
(quantity)
2-in. thickness
$1.06/ft2
No cost given
in quantity
$1.00-$0.75/ft2
$0.58/ft2
(quantity)
$1.10/ft2
(includes
delivery)
aQuantity costs include delivery.
Source: Sai and Zabcik, 1985, p 30.
-------
available. A compilation and descriptions are available in Koerner 1985 and
Geotechnical Fabrics Report 1987. The price for these materials can range
from $1.25 to more than $6.00 per square yard depending on the material and
its strength.
TABLE 12-5. RANGE OF COSTS FOR SAND AND GRAVEL
Media type Price (delivered $/yd3)a
Sand $3.00 (bank run)
(Fine, medium, coarse) $6.50 (clean)
Gravel $3.00 (bank run)
(Well-graded) $6.50 (clean)
Gravel $7.00 to $8.00
(Coarse, uniform)
aHaul distance can increase costs substantially.
Source: E. C. Jordan, 1984, p 22.
12.3.6 Piping
The most common usage of pipe in the lining system is as a component
of leachate collection and removal systems as described in Chapter 10. Pipe
appropriate for this usage includes polymeric, ferrous, fiberglass, and
concrete piping as discussed in Section 4.2.7. Cost data for piping are
presented in Table 12-6 as dollars per lineal foot for a 6-in. diameter pipe
of each material.
12.4 INSTALLATION COSTS OF LINERS
Certain factors affecting installation costs are specific to a type of
liner. Those factors for FMLs can be summarized as follows:
- Sand or soil with a limit on the maximum particle size may be needed
as a bedding for the FML. A soil cover may be needed to protect
the FML against damage by equipment such as tracked vehicles and
compactors that operate above the liners to compact refuse.
- Soil compaction and specific subgrade preparations may be needed for
the bedding on which the FML will be placed.
- Herbicides may need to be applied to the bedding surface to prevent
plant growth under a newly installed FML in order to prevent punctur-
ing of the FML.
12-9
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- Some materials are field seamed with different and very specific
techniques that may require more work effort and quality control than
others. Successful field seaming can require a fairly narrow range
of environmental conditions. Most liners cannot be placed in exces-
sive heat or cold, snow or rain, or on unstable or wet ground.
- Quality control and quality assurance.
TABLE 12-6. COSTS FOR PIPE OF DIFFERENT TYPES
Material
Polyvinyl chloride
High-density polyethylene
Type
Flexible
Smooth,
flexible
Costa,
Nonperforated
1.20-3.25
2.00-8.00
$/LF
Perforated
1.70-3.75
2.50-8.50
Acrylonitrile butadiene
styrene
Semirigid
3.00
3.50
Steel
Ductile iron
Corrugated,
semi flexible
Rigid
3.00
5.50
3.00
7.50
Fiberglass
Concrete-porous wall
Flexible
Rigid
10.0-20.00
(highly
variable)
1.30-1.55
Labor rate
for field
perforation
Not applicable
aCost per lineal foot for 6-in. diameter pipe.
Source: E. C. Jordan, 1984, pp 17-18.
12.5 CONSTRUCTION COSTS FOR EARTHWORKS
The cost of using soil as a construction material can vary widely.
Details such as groundwater level and local soil availability can affect
costs by a factor of two or more. Therefore, budgeting prior to preliminary
design work can be very difficult, and a meaningful cost estimate may require
a preliminary review of site conditions to form a conceptual design and
construction plan. Contingencies of 25% or more are often attached to such
estimates. Often the experience of local contractors is invaluable in
assessing the cost and practicality of a proposed design.
Most embankment construction for a surface impoundment is similar to
that in routine earthwork, as is discussed in Chapter 9.
12-10
-------
Table 12-7 lists the costs of major components of an embankment, and
the important factors that influence the respective costs.
TABLE 12-7.
UNIT COSTS FOR MAJOR EMBANKMENT COMPONENTS
(1986 Level of Costs)
Item
Estimated cost range Factors influencing cost
Excavation
Granular embankment
Cohesive embankment
Drain lines
Drain material
Riprap
Quality control
$1.50-25.00/cu yd
$2.00-15.00/cu yd
$2.00-20.00/cu yd
$10.00-50.00/ft
$8.00-25.00/cu yd
$15.00-30.00/cu yd
0.5-3% of contract
price/lump sum
Size, material disposal,
soil conditions, groundwater
conditions
Local availability, distance
to source, processing re-
quired, compaction require-
ment
Distance to borrow area,
natural moisture content,
compaction requirements,
soil workability
Type, trench depth, backfill
requirements, diameter
Gradation required, size of
drain, local availability,
compaction requirements
Local availability and dis-
tance to source
Difficulty of job, regula-
tory requirements, con-
tractor's conscientiousness
12.6 COSTS FOR LEACHATE COLLECTION AND REMOVAL SYSTEMS
Materials that may be used in the LCRSs include pipe of various types,
granular drainage media such as sand and gravel, synthetic drainage media
such as geonets and geocomposites, and geotextiles as filters, separators,
or protectors. Costs for the individual materials are discussed in Section
12.3. In addition to costs for the materials, there are costs for construc-
tion of the LCRS as well as for construction quality assurance.
E. C. Jordan (1984) developed an average cost per unit for LCRSs
with either granular media or synthetic drainage layer systems for a 4.8 acre
12-11
-------
containment unit. The specifications for the unit on which the cost esti-
mates were based is given in Table 12-8. The design of the system on which
the cost estimate of the granular drainage system was based is presented in
Figure 12-1. All itemized costs for major system components are presented in
Table 12-9. Costs include materials, installation, overhead, and profit.
This estimate shows considerable savings for synthetic drainage systems over
granular systems due to the greater ease in which the synthetic materials are
placed, and the use of minimum thickness materials. Use of the more costly,
high transmissivity geocomposites presented in Table 12-4 would bring costs
of the two systems into close proximity.
In actuality, the experience with leachate collection systems is
limited. A database on leachate collection systems, compiled for the EPA
(1983), indicated that the range of costs for single landfill systems ranged
from a minimum of $15,000 to maximum of $1,470,000, the median costs for
for which were $200,000. The largest site pumped quantities of around
5,550,000 gal/year of leachate; the median capacity was 22,500 gal/year
of leachate.
12.7 COSTS FOR A ONE-ACRE DOUBLE-LINED SURFACE IMPOUNDMENT
The basic design assumptions, both economic and technical, must be
established before a detailed cost estimate can be prepared for any system
involving construction with earthworks and large purchases of materials. A
cost model of a one-acre double-lined surface impoundment incorporating the
standards specified in the RCRA amendments of 1984 (Hazardous and Solid
Wastes Act) was developed by Sai and Zabcik (1985). The model uses a LOTUS
1,2,3 spreadsheet to calculate the design variables and the engineering and
construction costs.
Components of a double-lined waste containment unit are presented in
Table 12-1, and a cost summary based on a specific scenario is shown in Table
12-10. The scenario surface impoundment consists of an FML/composite double
liner, a sand drainage layer with pipe drains and collection sumps. The
surface impoundment is designed to contain 5 ft of liquid and have a surface
area of one acre. A slope of 3:1 was assumed as a typical value that should
provide adequate berm stability for the surface impoundment cost model.
Figure 5-4 presents a schematic cross section of the scenario surface
impoundment.
The cost of clearing and grubbing is dependent on the vegetation at the
construction site. For the cost calculations in Table 12-10, it was assumed
that the area was flat and had no trees. The cost model calculates a set of
surface impoundment optimum design dimensions for freeboard and minimizing
earthwork. These optimum impoundment dimensions are determined by using the
concept of fill efficiency ratio, which assumes that the most cost effective
dimensions for a given surface impoundment volume are those with the highest
ratio of storage volume to fill volume.
12-12
-------
TABLE 12-8. SPECIFICATIONS FOR UNIT USED TO ESTIMATE
COST OF LEACHATE COLLECTION AND REMOVAL SYSTEMS
Item
Criteria value
Disposal unit:
Site
Area
Dimensions
Waste layer depth
Side slopes3
Liner material
Drainage layer:
Slope
Depth:
Pipe in drainage media
Synthetic drainage layer
Drainage layer:
Pipe in
Synthetic
•ainage layer:
Pipe in drainage media
Synthetic drainage layer
Collection system:
Laterals
Headers
Discharge line
Geotextile wrap
Slope
Lateral spacing
Structures:
Manholes
Auxiliary cleanouts:
Pipe in drainage media
Pipe in synthetic media
Landfill
4.8 acres
350 x 600 ft
• • •
3:1
HOPE
2 ft
1/4 in.
b
Geonet
6-in. dia. PVC
8-in. dia. PVC
8-1n. dia. PVC
Polypropylene
0.005C
50 ft
perforated
perforated
solid wall
Precast concrete - 4-ft dia.
6-in.
None
dia. PVC - solid wall
aSide slopes at landfill and surface impoundments have been
designed at 3:1. Using this angle should avoid sloughing of
any of the drainage media evaluated (Bass et al, 1984).
bSee Figure 12-1.
CEPA guidance calls for a minimum slope of 2% in the collec-
tion system.
Source: E. C. Jordan, 1984.
12-13
-------
12in.
Minimum
¥ Protective Layer ? ^^^^^^if^fjflf'..*'
6 in. Diameter
Perforated Pipe
figure 12-1.
Top FML
Bedding Media-
Coarse, Uniform Gravel
Geotextile - Separator
FML
(Slope >2%)
Compacted
Soil Liner
Configuration of a granular drainage system for a secondary
leachate collection system. (Source: E. C. Jordan, 1984,
P 29).
TABLE 12-9. COST COMPARISON BETWEEN
GRANULAR AND SYNTHETIC DRAINAGE SYSTEMSa
Granular drainage
Pipe
Drainage layer
Filter fabric
Structures
Total
system
$ 11,500
106,300
3,600
7,000
$133,000
Synthetic drainage
Net
Pipe
Structures
Fittings
Total
system
$24,700b
3,000
5,100
2,200
$35,000
aSee Table 12-8 for specifics of cell used to estimate cost.
See Figure 12-1 for schematic cross section of granular
drainage system design.
of any of the geocomposite drainage mats listed in Table
12-4 would place costs for synthetic drainage systems much
closer to those for granular systems.
Source: E. C. Jordan, 1984, p 54.
The unit costs included in the model reflect average 1984 dollars
and do not include cost and profit margins. The unit costs were obtained
from Means (Godfrey, 1984) cost data and are for an average site condition
which may not reflect cost variations due to specfic location, construction,
or practice. Design, engineering, and supervisory services are not included
in the total cost of construction. These costs usually comprise between 8
and 20% of the total direct project costs. Other costs not estimated by
the model include land costs, leachate analysis and waste compatibility
testing costs, and other management costs. Construction costs used in these
12-14
-------
TABLE 12-10.
CONSTRUCTION COSTS FOR A SURFACE IMPOUNDMENT DESIGNED
TO CONTAIN FIVE FEET OF LIQUID3
Unit cost (1984)b
Component
Geotechnical investigation of site
Clearing and grubbing
Excavation
Grading and compaction
Berm construction (fill and spread)
Berm compaction
Clay liner
Compaction of clay liner
Drainage layer (sand)
Compaction of drainage layer
Protective soil
Geotextile protection layer
Top FML
Geotextile support
FML in bottom composite liner
Leachate drain pipe (main)
Leachate drain pipe (lateral)
Pump
Sump
Diversion ditch
Riprap
Subtotal (materials)
Subtotal (installation/construction
Total
Unit
site
acre
cu yd
sq yd
cu yd
cu yd
cu yd
cu yd
cu yd
cu yd
cu yd
sq ft
sq ft
sq ft
sq ft
ft
ft
ea
ea
ft
cu yd
)
Material
• • •
• • •
• • •
• • •
• • •
• • »
4.90
• • •
6.50
• • •
8.50
0.09
0.28
0.09
0.28
1.41
1.52
1,450.00
1,990.00
• • •
8.75
Installation/
construction
$12,441.00
1,406.30
2.14
0.57
2.19
1.37
2.73
1.15
2.73
1.24
2.73
0.07
0.18
0.07
0.18
2.16
1.11
265.00
385.00
2.41
11.25
Number
of units
1.0
1.5
15,613
8,113
1,979
1,979
8,023
8,023
2,172
2,172
2,192
49,958
49,958
49,958
56,983
218
840
1.0
1.0
1,295
324
Cost
$ 12,441
2,109
33,412
4,624
4,334
2,711
61,216
9,226
20,048
2,693
24,616
7,993
22,980
7,993
26,212
778
2,209
1,715
2,375
3,121
6,480
$118,857
$140,429
$259,286
aCosts are for a surface impoundment lined with an FML/composite double liner and constructed
with a secondary leachate collection system that uses a sand drainage layer.
bGodfrey, 1984.
Source: Sai and Zabcik, 1985.
-------
calculations were based on standard equipment and construction practices
and average climatic conditions.
12.8 COSTS FOR ADMIX AND SPRAYED-ON LINERS
Cost estimates for admix and sprayed-on asphalt membrane liners are
presented in Table 12-11. As with the cost estimates for the FMLs, the
costs shown include neither the costs for site and surface preparation, nor
the costs of a soil cover. Specific cost data for these liner types are
difficult to obtain and are heavily influenced by geographic location,
especially transportation costs.
TABLE 12-11. COST ESTIMATES FOR SOIL CEMENT, ASPHALT CONCRETE,
AND ASPHALT MEMBRANE LINERS
Installed
cost, $/sq yd
Liner type 1987a
Soil cement
6-in. thick + sealer (2 coats - each
0.25 gal/sq yd) 9.0Qb
Asphalt concrete, dense-graded paving
without sealer coat (hot mix, 4-in. thick) 3.40-5.60
Asphalt concrete, hydraulic (hot mix,
4-in. thick) 5.62-7.88
Bituminous seal (catalytically blown
asphalt) 1 gal/sq yd 3.15
Asphalt emulsion on mat (polypro-
pylene mat sprayed with asphalt emulsion) 1.00-2.00
Estimated installed costs on West Coast.
bQn large projects price can range from $4.50-6.75/sq yd. The
lower price applies to an installation of about 40 acres.
The costs for asphalt-concrete liners are closely related to those for
asphalt paving concrete. Existing equipment and technology are available
which can be used as is or with modification to install liners. Thus,
admix lining materials may be cost-effective for lining some waste disposal
impoundments, provided they meet the technical requirements.
12-16
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12.9 COMPARISON OF COSTS OF ALTERNATE LAND WASTE DISPOSAL TECHNOLOGIES
Hallowell et al (1984) compared the cumulative costs of four alterna-
tives for the management of hazardous wastes, including:
- An excavated conventional hazardous waste landfill.
- A mound-type landfill.
- Above-ground storage.
- Crystalline bedrock disposal.
The conventional landfill considered is a state-of-the-art (as of 1984)
secure chemical landfill, 30- to 40-ft below existing ground level and
containing liners, leachate collection system, cap, and soil cover. The
facility is developed on a cell basis.
The mound landfill involves the development of a base layer at existing
ground level that includes the installation of liners and leachate collection
systems, followed by the build-up of waste and cap or cover at a height of
about 40 feet above the original ground level. The facility is developed in
steps in separate cells, creating a series of mound structures.
Above-ground storage involves the storage of wastes in drums in en-
closed buildings and liquids in large tanks, either until ultimate disposal
at closure or until technologies or needs are developed to recycle or reuse
valuable constituents of the waste. The closure of such a site is charac-
terized by quick removal of all accumulated wastes, decontamination, and site
cleanup which would result in minimum or no post-closure monitoring.
Crystalline bedrock disposal involves permanent disposal in under-
ground vaults from a few hundred to 1,000 ft under the surface of the earth.
Three different annual capacities of facilities were considered for the
economic comparison:
- Low: 5,000 tons per year.
- Medium: 30,000 tons per year.
- High: 80,000 tons per year.
Data showing the comparison of cumulative costs are given in Table 12-12
and represented graphically in Figure 12-2.
12.10 COSTS OF QUALITY ASSURANCE
The cost of quality assurance is described in detail by Giroud and Fluet
(1986). They concluded that the major portion of the cost of quality
12-17
-------
assurance relating to a lining system for a waste storage or disposal unit is
in construction quality assurance. Table 12-13 shows the magnitude of funds
which should be budgeted for quality assurance of lining systems. The cost
percentages shown are for complete (100%) quality assurance documentation.
The actual cost percentage for a particular site will depend on the degree
of quality assurance desired (partial or full), the size of the project, the
quality of the design and the construction work, site-specific conditions,
and problems encountered.
TABLE 12-12. COMPARISON OF CUMULATIVE COSTS OVER 20 YEARS
OF FOUR ALTERNATIVE TECHNOLOGIES FOR MANAGEMENT OF HAZARDOUS WASTES
Waste capacity, ton/year
Type of disposal facility 5.000 30.000 80.000
Total cumulative costs,
millions of dollars
Conventional landfill 19.0 39.3 71.1
Mound landfill 19.4 40.2 68.8
Above-ground storage:
Without recycle 116.3 604.0 1,503.0
With recycle 57.0 294.4 729.3
Crystalline bedrock disposal 52.0 172.0 380.0
Pen-ton costs,
dollars/ton
Conventional landfill 190 67 44
Mound landfill 194 67 43
Above-ground storage:
Without recycle 1,163 1,007 940
With recycle 570 490 456
Crystalline bedrock disposal 520 290 240
Source: Hallowell et al, 1984.
An example was developed by Giroud and Fluet (1986) for typical costs
for third party quality assurance and are presented in Table 12-14. The
example is described as a moderately sized landfill (500,000 ft2) with a
lining system comprised of an FML top liner, a composite bottom liner (FML
over clay), geonets for primary and secondary leachate collection systems,
12-18
-------
and a geotextile for the primary leachate collection system filter. Such a
lining system will, therefore, contain 1,000,000 ft2 of FML. The instal-
lation might require from 10 to 20 weeks for completion. The costs shown in
Table 12-14 assume 12 weeks for completion of construction and that a com-
prehensive quality assurance plan is already in effect for the project. If
such a plan does not exist, then it should be prepared, and the cost must be
added to those shown in Table 12-14. The cost of the FML lining system used
in the example is estimated at $1,000,000 exclusive of the cost of quality
assurance. The cost of the quality assurance up through acceptance of the
unit by the owner/operator would, therefore, be approximately 26% of the
installed geosynthetic lining system cost.
10,000
1000
£8
1
w'
a
100
, Above Ground Storage
Without Recycle
'
Above Ground Storage
With Recycle
Crystalline Bedrock
Disposal
Landfill Technologies
10
1000
i l
5000 10.000 30,000 100,000
Facility Size, tons of waste per year
Figure 12-2. Comparison of the costs of four disposal technologies.
(Source: Hallowell et al, 1984).
12-19
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TABLE 12-13. COST OF QUALITY ASSURANCE
Phase
Percent of cost of
installed lining system
Design
Manufacturing
Fabrication
Lining system construction
Final report review
Operations
Closure system construction
(final cover)
Post closure care period
1 to 3
1 to 2
1 to 3
20 to 30
1 to 2
<1 per year
5 to 10
<1 per year
Source: Fluet, 1987.
TABLE 12-14. COST OF THIRD PARTY QUALITY ASSURANCE
FOR DOUBLE-LINED 500,000 FT2 WASTE LANDFILL UNIT
Phase
Design
Manufacturing
Fabrication
Personnel
Managing engineer
Manager
Managing engineer
Manager
Monitor
Installation Managing engineer
Manager
Monitor(s)
Total personnel cost
Laboratory
Total cost
costs
Number
1
1
1
1
1
1
1
1 to 10
Time3
2 to 8 days
2 to 5 days
0 to 1 day
0 to 1 day
1 to 2 weeks
15 to 25 days
11 to 12 weeks
4 to 10 weeks
Typical
costb
$ 4,000
3,500
500
300
4,000
17,000
45,000
170,000
$244,300
15,000
$259,300
aAssume a total completion time of 12 days.
blncludes travel and daily allowance.
Source: Giroud and Fluet, 1986.
12-20
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12.11 REFERENCES
Bass, J. M., P. Deese, M. Broome, J. Ehrenfeld, D. Allen, and D. Brunner.
1984. Design, Construction, Inspection, Maintenance, and Repair of
Leachate Collection and Cap Drainage Systems. Draft Report. EPA
Contract No. 68-03-1822. U.S. Environmental Protection Agency, Cin-
cinnati, OH. Cited in: E. C. Jordan Company. 1984. Performance
Standard for Evaluating Leak Detection. Draft Final Report. EPA
Contract No. 68-01-6871, Work Assignment No. 32. U. S. Environmental
Protection Agency, Washington, D.C. 116 pp.
E. C. Jordan Company. 1984. Performance Standard for Evaluating Leak
Detection. Draft Final Report. EPA Contract No. 68-01-6871, Work
Assignment No. 32. U.S. Environmental Protection Agency, Washington,
D.C. 116 pp.
EPA. 1983. Environmental Protection Agency Version 2 of the Landfill
Data, Westat DataBase. Output prepared by DRPA, Inc. for Marlene Suit.
Cited in: Bass J. 1986. Avoiding Failure of Leachate Collection and Cap
Drainage Systems. EPA 600/2-86-058 (PB 86-208733/AS). U.S. Environ-
mental Protection Agency, Cincinnati, OH.
EPRI. (In preparation). Materials, Design, and Construction of Liner
Systems for Coal-Fired Power Plant Waste Disposal Facilities. Elec-
trical Power Research Institute, Palo Alto, CA.
Fluet, J. E., Jr. 1987. Geosynthetic Lining Systems and Quality Asssur-
ance—State of Practice and State of the Art. In: Geosynthetics 87'.
Proceedings of Geosynthetics Conference, New Orleans, LA, February
25-25, 1987. Vol. 2. International Fabrics Association, St Paul, MN.
pp 530-541.
Geotechnical Fabrics Report. 1987. Product Reference Guide and Directory.
Volume 5, November/December, pp 6-75.
Giroud, J. P., and J. E. Fluet, Jr. 1986. Quality Assurance of Geosyn-
thetic Lining Systems. Geotextiles and Geomembranes 3(4).-249-287.
Godfrey, R. S. (Ed.). 1984. Building Construction Cost Data. 42nd Ed.
Robert Snow Means Company, Inc. Kingston, MA. 434 p.
Koerner, R. M. 1985. Designing with Geosynthetics. Prentice-Hall. Engle-
wood Cliffs, NJ. 424 pp.
Hallowell, J. B., D. P. DeNiro, and J. S. Lawson, Jr. 1984. Comparative
Assessment of Alternatives for Waste Disposal and Storage. In: Proceed-
ings of National Conference on Hazardous Wastes and Environmental,
Emergencies. Silver Spring, MD. pp 269-274.
Sai, J., and J. D. Zabcik. 1985. Estimate of Surface Impoundment Construc-
tion Costs Under the RCRA Amendments of 1984. Contract No. 68-03-1816.
U.S. Environmental Protection Agency, Cincinnati, OH. 48 pp.
12-21
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APPENDIX A
SIGNIFICANT WASTE SOURCES AND TYPES OF WASTES
This appendix presents examples of significant waste sources and the
types of wastes generated by these sources. Selected representative wastes
of the following types are discussed:
- Municipal solid waste.
- Hazardous wastes from eleven industries:
-- Electroplating and metals finishing.
— Inorganic chemicals.
-- Metal smelting and refining.
-- Organic chemicals.
-- Paint and coatings formulating.
-- Pesticide.
-- Petroleum refining.
-- Pharmaceutical.
-- Pulp and paper.
— Rubber and plastics.
-- Soap and detergent.
- Uranium tailings.
- Other nonradioactive wastes.
- Substances stored in underground storage tanks.
This appendix is intended only to be illustrative. The objective is to
give examples of wastes from the different sources that may be encountered
and which may or should be impounded in lined facilities. Interactions
between wastes and specific liner materials are discussed in Chapter 5.
A-l
-------
MUNICIPAL SOLID WASTE
Description of the Waste
Municipal solid waste (MSW), the refuse from residential and commercial
sources, is typically composed of paper, glass, plastics, rubber, wood,
metal, food and garden wastes, ceramics, rocks, textiles, leather, etc.
Major components and rough wet weight percents are presented in Table A-l
from Ham et al (1979). See Wigh (1979) for additional data. It is, however,
the leachate produced by the waste, whether primary or secondary, that is of
principal concern with respect to pollution and liner durability.
Characteristics of Leachate From Municipal Solid Waste
The leachate produced from municipal refuse is a highly complex liquid
mixture of soluble, organic, inorganic, ionic, nonionic, and bacteriological
constituents and suspended colloidal solids in a principally aqueous medium.
It contains products of the degradation of organic materials and soluble ions
which may present a pollution problem to surface and ground waters (Phillips
and Wells, 1974). The quality of the leachate depends on the composition of
the waste and the combined physical, chemical, and biological activities.
The precise composition of leachate is waste and site specific, depend-
ing on such variables as type of waste, amount of infiltrating water, age of
landfill, and pH. Table A-2 lists parameters of leachate which are used as
analytical indicators of landfill leachate in the groundwater near a landfill
(EPA, 1977). Tables A-3 and A-4 present data to show the complexity in
composition of actual leachate from MSW, its site specific character, and its
variation with time.
Griffin and Shimp (1978) compared the analyses of municipal landfill
leachate with drinking water standards. Chemical oxygen demand (COD) and
biochemical oxygen demand (BOD) of landfill leachates were generally high and
the pH ranged from 4 to 9. Alkalinity, hardness, phosphate, nitrogen, heavy
metals, and concentrations of other elements were also determined. The
levels of these components varied over very wide ranges as shown in Tables
A-3 and A-4.
Leachates generated in the disposal of hazardous wastes may include high
concentrations of such metals as mercury, cadmium, and lead; toxic sub-
stances, such as barium and arsenic; organic compounds, including chlorinated
solvents, aromatic hydrocarbons, and organic esters; and various corrosive,
ignitable, or infectious materials.
Potential Pollution by MSW Leachate
Municipal landfill leachates degrade groundwater quality by introducing
the constituents shown in Tables A-3 and A-4, as well as biological con-
tamination (Phillips and Wells, 1974).
A-2
-------
TABLE A-l. COMPOSITION AND ANALYSIS OF AN AVERAGE MUNICIPAL REFUSE FROM STUDIES BY PURDUE UNIVERSITY
Analysis, percent dry
Percent of
all refuse,
Component by weight
Rubbish, 64%:
Paper
Wood
Grass
Brush
Greens
Leaves
Leather
Rubber
Plastic
Oils, paints
-P, Linoleum
i, Rags
Street sweepings
Dirt
Unclassified
Food Wastes, 12%:
Garbage
Fats
Noncombustibles, 24%:
Metals
Glass & ceramics
Ashes
Composite refuse,
as received:
All refuse
42.0
2.4
4.0
1.5
1.5
5.0
0.3
0.6
0.7
0.8
0.1
0.6
3.0
1.0
0.5
10.0
2.0
8.0
6.0
10.0
100
Moisture
percent, by
weight*3
10.2
20.0
65.0
40.0
62.0
50.0
10.0
1.2
2.0
0.0
2.1
10.0
20.0
3.2
4.0
72.0
0.0
3.0
2.0
10.0
20.7
Volatile
matter
84.6
84.9
• • •
• • •
70.3
• • •
76.2
85.0
• • •
• • •
65.8
93.6
67.4
21.2
• • •
53.3
* * •
0.5
0.4
3.0
• • •
Carbon
43.4
50.5
43.3
42.5
40.3
40.5
60.0
77.7
60.0
66.9
48.1
55.0
34.7
20.6
16.6
45.0
76.7
0.8
0.6
28.0
28.0
Hydro-
gen
5.8
6.0
6.0
5.9
5.6
6.0
8.0
10.4
7.2
9.7
5.3
6.6
4.8
2.6
2.5
6.4
12.1
0.04
0.03
0.5
3.5
Oxygen
44.3
42.4
41.7
41.2
39.0
45.1
11.5
• • •
22.6
5.2
18.7
31.2
35.2
4.0
18.4
28.2
11.2
0.2
0.1
0.8
22.4
weight3
Nitro-
gen
0.3
0.2
2.2
2.0
2.0
0.2
10.0
• • •
• • •
2.0
0.1
4.6
0.1
0.5
0.05
3.3
0.0
• • •
• • •
• • •
0.33
Sulfur
0.20
0.05
0.05
0.05
0.05
0.05
0.40
2.0
• • •
* • •
0.40
0.13
0.20
0.01
0.05
0.52
0.00
• • •
• • •
0.5
0.16
Non
combus-
tibles
6.0
1.0
6.8
8.3
13.0
8.2
10.1
10.0
10.2
16.3
27.4
2.5
25.0
72.3
62.5
16.0
0.0
99.0
99.3
70.2
24.9
Source: Ham et al, 1979.
aAnalysis of the respective components.
^Moisture content of the respective components in the waste.
-------
TABLE A-2. PARAMETERS FOR CHARACTERIZING MSW LEACHATE
Chemical
Physical
Organic
Inorganic
Biological
Appearance
PH
Oxidation-reduction
potential
Conductivity
Color
Turbidity
Temperature
Odor
Phenols
Chemical oxygen demand (COD)
Total organic carbon (TOC)
Volatile acids
Organic nitrogen
Tannins, lignins
Ether soluble (oil and grease)
MBAS
Organic functional groups
as required
Chlorinated hydrocarbons
Total bicarbonate
Solids (TSS, TDS)
Volatile solids
Chloride
Phosphate
Alkalinity and acidity
Nitrate-N
Nitrite-N
Ammonia-N
Sodium
Potassium
Calcium
Magnesium
Hardness
Heavy metals (Pb, Cu,
Ni, Cr, Zn, Cd, Fe,
Mn, Hg, As, Se, Ba,
Ag)
Cyanide
Fluoride
Biochemical oxygen
demand (BOD)
Coliform bacteria
(total, fecal;
fecal streptococcus)
Standard plate count
Source: EPA (1977).
-------
TABLE A-3. COMPOSITION OF THREE MSW LANDFILL LEACHATES
Concentration of Constituents (mg/L), Except pH and Electrical Conductivity
Constituent
BOD5
COD
TOC
Total solids
Volatile suspended solids
Total suspended solids
Total volatile acids as acetic acid
Acetic acid
Propionic acid
Butyric acid
Valeric acid
Organic nitrogen as N
Ammonia nitrogen as N
Kjeldahl nitrogen as N
pH
Electrical conductivity (umho/cm)
Total alkalinity as CaC03
Total acidity as CaCOs
Total hardness as CaC03
Chemicals and metals:
Arsenic
Boron
Cadmium
Calcium
Chloride
Chromium (total)
Copper
Iron (total)
Lead
Magnesium
Manganese
Mercury
Nickel
Phosphate
Potassium
Silica
Sodium
Sulfate
Zinc
Wigh
(1979)
• • •
42,000
• * •
36,250
• • •
• • •
• • •
• • •
• • •
• • •
* * *
• • •
950
1,240
6.2
16,000
8,965
5,060
6,700
• • •
• • •
• • •
2,300
2,260
• • •
• • •
1,185
• • •
410
58
• • •
• • •
82
1,890
• • •
1,375
1,280
67
Source of data
Breland
(1972)
13,400
18,100
5,000
12,500
76
85
9,300
5,160
2,840
1,830
1,000
107
117
• • •
5.1
• • •
2,480
3,460
5,555
• • •
• • •
• • •
1,250
180
• • •
• • •
185
• • •
260
18
• • *
• * *
1.3
500
• • *
160
• • *
• • •
Griffin
and Shimp
(1978)
* • •
1,340
• • •
• • •
* • *
• * •
333
• • •
• • *
• • •
• • •
• • •
862
• • •
6.9
• • •
• • •
• • •
• • •
0.11
29.9
1.95
354.1
1.95
<0.1
<0.1
4.2
4.46
233
0.04
0.008
0.3
• • •
• • •
14.9
748
<0.01
18.8
A-5
-------
TABLE A-4. CHARACTERISTICS OF MSW LEACHATES^
Constituent
BOD5
COD
Total dissolved solids
Total suspended solids
Total nitrogen
pH
Electrical conduc-
tivity (pmho/cm)
Total alkalinity
as CaC03
Total hardness
as CaC03
Chemicals and Metals:
Cadmium (Cd)
Calcium (Ca)
Chloride (Cl)
Copper (Cu)
Iron (Fe)- total
Lead (Pb)
Magnesium (Mg)
Manganese (Mn)
Phosphate (P)
Potassium (K)
Sodium (Na)
Sulfate (504)
Zinc (Znj
Reference^
(mg/L)
9-54,610
0-89,520
0-42,276
6-2,685
0-1,416
3.7-8.5
...
0-20,850
0-20,800
...
5-4,080
34-2,800
0-9.9
0.2-5,500
0-5.0
16.5-15,600
0.6-1,400
0-154
2.8-3,770
0-7,700
1-1,826
0-1,000
Reference0
(mg/L)
...
100-51,000
...
...
20-500
4.0-8.5
...
...
200-5,250
...
...
100-2,400
...
200-1,700
...
...
...
5-130
...
100-3,800
25-500
1-135
Reference^
(mg/L)
7,500-10,000
16,000-22,000
10,000-14,000
100-700
5.2-6.4
6,000-9,000
800-4,000
3,500-5,000
0.4
900-1,700
600-800
0.5
210-325
1.6
160-250
75-125
• * •
295-310
450-500
400-650
10-30
Reference6
(mg/L)
• • •
500-1,000
...
...
...
6.3-7.0
1,200-3,700
630-1,730
390-800
...
111-245
100-400
<0. 04-0. 11
20-60
...
22-62
1.02-1.25
21-46
107-242
106-357
13-84
<0. 04-0. 47
Reference^
Fresh
14,950
22,650
12,620
327
989
5.2
9,200
...
...
2,136
742
0.5
500
...
277
49
7.35
...
...
...
45
Old
• • •
81
1,144
266
7.51
7.3
1,400
...
• • *
• • •
254
197
0.1
1.5
...
81
• * •
4.96
...
...
...
0.16
(1975a). DEPA (1973).
^Brunner and Carnes (1974).
csteiner et al (1971). dQenetelli and Cirello (1976). 6Ham (1975).
-------
The quantity of leachate produced is a function of the moisture content
of the waste itself and the volume of water added through infiltration and
percolation from surface and ground sources. Leachate is being recycled in
some installations to enhance biodegradation in the landfill by providing
nutrients and water. The quantity of leachate that leaves the landfill and
the pollution potential are thus reduced.
One of the reasons for the development of the proposed TCLP (EPA, 1986)
is the concern of possible codisposal of volatile solvents and other organics
in MSW. The proposed procedure will allow for the determination of the
volatile organics that are in the proposed list for toxicity characteristic.
Potential Effects of MSW Leachate Upon Liners
MSW leachate is not inert toward lining materials; constituents of the
leachate can affect liners in different ways, depending on their concentra-
tions in the leachate and on the specific liner materials. Furthermore, the
effects of the constituents can be synergistic and can vary with time as the
concentrations change with the aging of the waste. Dissolved salts and ions
may be damaging to some lining materials, particularly soils and clays.
Acidity or alkalinity may dissolve components of soils or soil cements.
Organic molecules (indicated by volatile acid content, volatile solid, and
total organic carbon (TOC) can be damaging to rubber and plastic liners
causing them to swell, to become more permeable and softer and lose in
properties, such as tensile strength and tear resistance, and thus to be more
easily torn and damaged. Uater also can cause some liners to swell. These
effects are discussed in detail in Chapter 5. Also discussed in Chapter 5 is
the need for compatibility testing when the waste liquid or leachate is known
to contain constituents that are aggressive to some types of liner materials.
Gas Production in MSW
Gases are also produced in the decomposition of organic matter in MSW
landfills. These gases, primarily methane and carbon dioxide, may present
problems if their migration is not controlled or if they are not collected.
Methane is flammable, can be explosive, is damaging to plants and trees, and,
in high enough concentration, may result in asphyxiation of animals and
people; it is of commercial value as a heating fuel and some generated in MSW
landfills is being used in this manner. Carbon dioxide is absorbed in leach-
ate and tends to lower pH and thus to solubilize calcium, magnesium, and
other metals.
HAZARDOUS WASTES BY INDUSTRY
Industrial wastes are a major source of hazardous wastes, the components
of the latter are usually metals, strong acids or bases, and a large array of
organic and inorganic chemicals. As shown in Table A-5, taken from the EPA
Report to Congress on the disposal of hazardous wastes (EPA, 1974a), each
industry produces wastes with different characteristics and components.
Also, wastes generated by the same industry vary from source to source. The
A-7
-------
TABLE A-5. REPRESENTATIVE HAZARDOUS SUBSTANCES WITHIN INDUSTRIAL WASTE STREAMS
Hazardous substances
Industry
Battery
Chemical manufac-
turing
Electrical and
electronic
Electroplating and
metal finishing
Explosives
Leather
fining and metallurgy
is Paint and dye
Pesticide
Petroleum and coal
Pharmaceutical
Printing and
dupl icating
Pulp and paper
Textile
Chlorinated
As Cd hydrocarbons3 Cr
••• A ••• A
•••••• A A
••• ••• A •••
••* A **» A
X
... x
A A • • • A
••• A *•• A
y y
A ••• A •••
A *•• A •••
A *•• ••• •••
x ... ... x
... X
Cu Cyanides Pb
X
X
XXX
A A • • *
x ... x
... ...
XXX
XXX
X X
X
... ...
X ... X
...
X
Hg
...
X
X
* • •
X
X
X
X
• • *
X
• • •
X
...
Misc.
organics*3 Se Zn
• • • • • • A
A * • • • * *
• • • A • * •
• • * • • * A
x
x
X X
A A • • •
A • • • A
x
A A • * •
x
A • • • • • *
alncluding polychlorinated biphenyls.
bpor example: acrolein, chloropicrin, dimethyl sulfate, dinitrobenzene, dinitrophenol, nitroaniline, and
pentachlorophenol.
Source: EPA (1974a).
-------
chemical nature and reactivity, as well as concentration of the waste com-
ponents, must be considered when designing a lining system for a specific
waste storage or disposal facility. The characteristics of the wastes from
several selected industries are discussed below, and are illustrative of
specific wastes which are generated and must be disposed of in environ-
mentally sound methods. Special attention is given those constituents in the
waste liquids that are aggressive to lining materials.
Solid wastes that have been identified as hazardous wastes by the EPA
are listed in 40 CFR 261, Subpart D. These wastes include:
- Generic hazardous wastes from nonspecific sources, such as spent
halogenated solvents used in degreasing, and sludges from the solvents
used in degreasing operations. Identified wastes have been assigned
an industry and EPA hazardous waste number preceded by the letter "F".
The bases for identifying these wastes as hazardous are presented in
Appendix 7 of 40 CFR 261; specific hazardous constituents that are
presented in the individual wastes are shown.
- Hazardous wastes from specific sources, such as bottom sediment sludge
from the treatment of wastewater from wood preserving processes that
use creosote and pentachlorophenol. Identified wastes have been
assigned an industry and EPA hazardous number preceded by the letter
"K". The bases for identifying these wastes as hazardous are presented
in Appendix 7 of 40 CFR 261; specific hazardous constituents that are
presented in the individual wastes are shown.
- Wastes which are discarded commercial chemical products, off-speci-
fication products, container residues, and spill residues and which
have been generically identified as either "acute hazardous wastes" or
"toxic wastes." These terms are defined in 40 CFR 261, Subpart B.
The generic commerical chemical products, the manufacturing chemical
intermediates, and off-specification commercial chemical products and
manufacturing chemical intermediates that have been identified as
acute hazardous wastes have been assigned a hazardous waste number
preceded by a "P"; those that have been identified as toxic wastes
have been assigned a hazardous waste number preceded by a "U".
Electroplating and Metals Finishing Industry
The electroplating industry can be classified into three principal
segments: plating, metal finishing, and the manufacture of printed circuit
boards. The plating segment can be further subdivided into common metal
electroplating, precious metal electroplating and electroless plating.
Subsegments of the metal finishing category include: anodizing, chemical
conversion coating, chemical milling, etching, and immersion plating.
Because of the heavy metal content of most wastes from the electroplating and
metal finishing operations, many wastes from this industry may be hazardous;
appropriate tests should be run to determine whether the waste liquids are
hazardous.
A-9
-------
In common metal electroplating, a ferrous or nonferrous basis material
is electroplated with copper, nickel, chromium, zinc, tin, lead, cadmium,
iron, aluminum, or combinations of these elements. Precious metal electro-
plating also uses either a ferrous or nonferrous basis material, but the
metal plated onto the basis material is either gold, silver, palladium,
platinum, rhodium, or combinations of these metals. Electroless plating is
used on both metals and plastics.
Anodizing, coatings (e.g. chromating or phosphating), coloring, and
immersion plating processes apply a surface coating to a workpiece for
specific functional or decorative purposes. Chemical milling and etching
processes are used to produce specific design configurations and tolerances
on metal parts by controlled dissolution with chemical reagents or etchants.
Wastewaters from plating and metal finishing operations are discharged
from all three phases of the electroplating process: workpiece pretreatment;
the plating, coating, or basis material removal process; post treatment.
Wastewaters are generated by rinse water disposal, plating or finishing bath
dumping, ion-exchange unit regenerant bleed streams, vent scrubber dis-
charges, and maintenance discharges (EPA, 1979).
Treatment may involve degreasing with soaps, alkaline cleaning (some-
times with the aid of wetting agents), acid dipping, or, in the case of
aluminum alloys, desmutting to remove finely divided particles of base
material. The compositions of treatment cleaners (and thus, waste streams)
vary with the type of base metal being cleaned and the kind of material being
removed.
Wastewater constituents generated from the electroplating depend on the
metals being plated and the plating solution used. Table A-6 lists some of
the various types of plating solutions used for electroplating. Plating
solutions for the metals in the platinum group are proprietary. The most
common plating solutions for electroless plating are copper and nickel,
although iron, cobalt, gold, palladium, and arsenic are also used. Of
particular concern among the constituents of electroless plating baths are
the chelating agents, which are used to hold the metal in solution (so the
metal will not plate out indiscriminately). There are three main types of
chelating agents: amino carboxylic acids, amines, and hydroxy acids. One of
the drawbacks in the use of chelating agents is the difficulty in precipitat-
ing chelated metals out of wastewater during treatment.
Wastes from metal finishing operations come from cleaning, pickling,
anodizing, coating, etching, and related operations. The constituents in
these wastes include the basic material being finished, as well as the
components in the processing solutions. Baths used for anodizing, coating,
and etching usually contain metal salts, acids, bases, dissolved basis
metals, complexing agents, and other deposition control agents. Bath con-
stituents for chemical removal of basis metals include mineral acids, acid
chlorides, alkaline ammonium solutions, nitro-organic compounds, and such
compounds as ammonium peroxysulfate.
A-10
-------
TABLE A-6. TYPICAL ELECTROPLATING SOLUTIONS
Plating compound
Cadmium cyanide
Cadmium fluoborate
Chromium electroplate
Copper cyanide
Electroless copper
Gold cyanide
Acid nickel
Silver cyanide
Zinc sulfate
Concentration
Constituents (g/L)
Cadmium oxide
Cadmium
Sodium cyanide
Sodium hydroxide
Cadmium fluoborate
Cadmium (as metal)
Ammonium fluoborate
Boric acid
Licorice
Chromic acid
Sulfate
Fluoride
Copper cyanide
Free sodium cyanide
Sodium carbonate
Rochelle salt
Copper nitrate
Sodium bicarbonate
Rochelle salt
Sodium hydroxide
Formaldehyde (37%)
Gold (as potassium
gold cyanide)
Potassium cyanide
Potassium carbonate
Dipotassium phosphate
Nickel sulfate
Nickel chloride
Boric acid
Silver cyanide
Potassium cyanide
Potassium carbonate (minimum)
Metallic silver
Free cyanide
Zinc sulfate
Sodium sulfate
Magnesium sulfate
22.5
19.5
77.9
14.2
251.2
94.4
59.9
27.0
1.1
172.3
1.3
0.7
26.2
5.6
37.4
44.9
15
10
30
20
100 mL/L
8
30
30
30
330
45
37
35.9
59.9
15.0
23.8
41.2
374.5
71.5
59.9
Source: Metal Finishing Guidebook and Directory (1979).
A-ll
-------
Post treatment processes in the plating segment encompass chemical
conversion coatings (chromating, phosphating, and coloring), which are
process steps for the metal finishing segment. Post treatment processes for
metal finishing include: sealing and coloring of anodic coatings, bleaching
or dyeing of chromate coatings, and chemical rinsing after phosphating.
Table A-7 is a compilation of the various pollutants found in each
subsegment of the electroplating industry. The concentrations presented are
the range of values for each constituent, based on a statistical analysis of
50 metal finishing plants and 67 plating establishments (EPA, 1979).
Hallowell et al (1976) identified four waste streams as being destined
for land disposal, i.e. water pollution control sludges, process wastes,
degreasing sludges, and the salt precipitates from electroless nickel bath
regeneration. Hallowell et al have estimated the quantities of these which
could be generated in 1975, 1977, and 1983. These data are presented in
Table A-8.
Inorganic Chemicals Industry
The waste streams of a few of the specific industries in this category
are briefly described in this subsection.
The chlor-alkali industry, whose main product is chlorine, also produces
soda ash (NaOH) and potash (KOH) as co-products. Brine-purification sludges
resulting from this industry contain mainly calcium carbonate, magnesium
hydroxide, barium sulfate, and water. These slightly hazardous or non-
hazardous wastes do not necessarily require strict landfilling precautions or
procedures. Lead carbonate and asbestos waste products must be handled more
carefully. Lead must be completely isolated from the environment before land
disposal. Asbestos is insoluble, but the dust and small fibers present a
serious potential health hazard. The surface of a disposal site for asbestos
should be protected from wind and erosion. Chlorinated hydrocarbons and
mercury are also by-products of certain processes.
The hazardous waste products from inorganic pigment manufacture include
chrome and small amounts of mercury or lead. Most of the mercury, lead,
zinc, and antimony is reclaimed. Minimally toxic wastes such as chlorides
and nontoxic metal oxides from ore residues are usually disposed of in
municipal sanitary landfills.
Other inorganic chemicals produce wastes such as ore residues, silicates
or easily neutralized liquids. Most hazardous components are reclaimed or
become part of a saleable by-product. Those hazardous components not re-
claimed are usually disposed of in lined impoundment facilities (Hallowell
et al, 1976).
A-12
-------
TABLE A-7. CHARACTERIZATION OF WASTE STREAM FROM ELECTROPLATING INDUSTRY
Pollutant
parameter
Copper
Nickel
Chromium, total
Chromium,
hexavalent
Zinc
Cyanide, total
Cyanide,
amenable
Fluoride
Cadmi urn
Lead
Iron
Tin
Phosphorus
Total suspended
solids
Silver
Gold
Palladium
Platinum
Rhodium9
Common metals
plating
0.032-272.5
0.019-2,954
0.088-525.9
0.0005-534.5
0.112-252.0
0.005-150.0
0.003-130.0
0.022-141.7
0.007-21.60
0.663-25.39
0.410-1,482
0.060-103.4
0.020-144.0
0-10,000
Segment
Precious
metals
plating
0.005-9.970
0.003-8.420
0.020-144.0
0-10,000
0.050-176.4
0.013-24.89
0.038-2.207
0.112-6.457
0.034
of industry - concentrations
Electroless
plating Anodizing
0.002-47.90
0.028-46.80
0.268-79.20
0.005-5.000
0.005-12.00 0.005-78.00
0.005-1.00 0.004-67.56
0.110-18.00
0.030-109.0 0.176-33.0
0-40 36-924.0
(mg/L)
Coatings
0.190-79.20
0.005-5.000
0.138-200.0
0.005-126.0
0.004-67.56
0.410-168.0
0.102-6.569
0.060-53.30
20-5,300
Chemical
milling and
etching
0.206-272.5
0.088-525.9
0.005-334.5
0.112-200.0
0.005-126.0
0.005-101.3
0.022-141.7
0.075-263.0
0.068-103.4
0.060-144.0
0-4,300
aOnly one plant had a measurable level of this pollutant.
Source: EPA (1979).
-------
TABLE A-8. HAZARDOUS WASTES DESTINED FOR LAND DISPOSAL
FROM THE ELECTROPLATING AND METALS FINISHING INDUSTRY
(JOB SHOPS) - DATA IN METRIC TONS ON A DRY BASIS
Type of waste
Water pollution control
sludges
Process wastes
Degreaser sludges
Electroless nickel
wastes
Total
1975
19,740
42,141
5,434
11,422
78,737
1977
56,399
42,141
5,434
11,422
115,396
1983
73,882
55,206
7,118
15,063
151,269
Source: Hallowell et al (1976).
Metal Smelting and Refining Industry
Smelting and refining of metal includes the following major operations
and industry segments:
- Coking produces the residue (coke) by the destructive distillation of
coal, which serves as a fuel and a reducing agent in the production of
iron and steel.
- Steel production methods include open hearth, basic oxygen furnace,
blast furnace, and electric furnace.
- Steel finishing involves a number of processes that impart desirable
surface or mechanical characteristics to steel.
- Ferro alloy production produces the iron-bearing products which
contain considerable amounts of one or more alloying elements such as
chromium, silicon, or manganese.
- Iron foundries mold or cast hot iron into desired shapes.
- Nonferrous metal smelting and refining involves the purification of
nonferrous metal concentrates drawn from ores or scrap into refined
metals and metal products.
A general list of the sources of potentially hazardous waste streams gener-
ated by metal smelting and refining and the constituents of these waste
streams that are considered potentially hazardous or aggressive to lining
materials are given in Table A-9.
A-14
-------
TABLE A-9. POTENTIALLY HAZARDOUS WASTE STREAMS GENERATED BY THE METAL SMELTING AND REFINING INDUSTRY
Product or activity
Waste stream
Constituents that are hazardous or aggressive to liners
:>
i
Coking
Electric furnace production
of steel
Steel finishing
Ferro-chromiurn-silicon production
Ferro-chrome production
Ferro-manganese production
Gray and ductile iron foundry
(Cupola furnace)
Primary copper smelting
Primary lead smelter
Primary zinc smelter
Primary aluminum smelting
Secondary lead smelting
Ammonia still lime sludge.
Decanter tank tar sludge.
Emission control dusts or
sludges.
Spent pickle liquor.
Sludge from lime treatment
of spent pickle liquor.
Emission control dust or
sludge.
Emission control dust or
sludge.
Emission control dust or
sludge.
Emission control dust or
sludge.
Acid blowdown slurry.
Surface impoundment
solids.
Wastewater treatment
sludge or acid plant
blowdown.
Electrolytic anode slimes
or sludges.
Cadmium plant leach.
Spent potliner (cathodes).
Emission control dust or
or sludge.
Oil and grease, cyanide, naphthalene, phenolic compounds,
arsenic, heavy metals.
Oil and grease, phenol, naphthalene, pyrites, polyaromatics,
nitrogen, heterocycles, heavy metals.
Metals, e.g. chromium, lead, cadmium.
Metals, e.g. chromium, lead, high pH.
Metals, e.g. chromium, lead.
Metals, e.g. chromium.
Metals, e.g. chromium, lead.
Metals, e.g. chromium, lead, manganese.
Metals, e.g. cadmium, lead.
Metals, e.g. antimony, arsenic, lead, cadmium, copper,
selenium, zinc.
Metals, e.g. arsenic, cadmium, lead, mercury.
Metals, e.g. arsenic, cadmium, selenium, zinc.
Metals, e.g. lead, cadmium, zinc.
Metals, e.g. lead, cadmium, zinc.
Metals, e.g. copper, lead, cyanides, fluorides.
Metals, e.g. chromium, lead, cadmium, zinc.
Source: Brown, K. W., and Associates (1980; pp 368-376).
-------
Organic Chemicals Industry
The petrochemical and organic chemicals industry is second only to
petroleum refining in the volume of hazardous wastes it generates. Indus-
trial petrochemical complexes and specialized organic chemical plants
generate a wide variety of organic products and, as a result, each can
generate an array of organic-rich hazardous wastes. The basic feedstocks for
organic chemical producers are supplied principally by petrochemical plants
and consist of gaseous and liquid fractions of crude oil produced in oil
refineries. The feedstocks are used to manufacture "end use" organic pro-
ducts such as plastics, rubber, Pharmaceuticals, paints, pesticides, organic
pigments, inks, adhesives, explosives, soaps, synthetic fibers, and cos-
metics. Many of the large petrochemical plants themselves also produce "end
use" organic products such as pesticides, solvents, or heat transfer fluids.
Several of the segments of the organic chemicals industry, such as
pesticides, Pharmaceuticals, rubber, and plastics, are discussed individually
in separate subsections.
The compositions of the waste streams are not well documented and many
are considered to be proprietary. In addition, the waste streams can be a
complex mixture of streams coming from different processes within a given
plant; nevertheless, most of these waste streams will contain organic con-
stituents as well as inorganic (EPA, 1975b).
Paint and Coatings Formulating Industries
The paint and allied products industries utilize many organic and
inorganic raw materials, some of which are present in the wastes. There is
no waste stream in the sense of wastes as by-products of production. The
wastes come mainly from the packaging of raw materials, air and water pol-
lution control equipment, off-grade products and spills, most of which is
reclaimed and reused except for paint absorbed onto the final clean-up
material. Coatings containing significant amounts of toxic metals are
reworked and wastes contain little or no metallic residues. Most spoiled
batches are incorporated in later batches whenever possible and spills are
salvaged.
In the formulation of paint and coatings, a number of metal compounds
are used as pigments; oils and polymer resins are used as bases and solvents
are used as thinners. These ingredients become part of the waste as spoiled
batches or spills. Such waste constitutes about 0.2% of production. Toxic
chemical usage is strictly limited so a proportionally small amount of toxic
substances (mainly mercury and lead) reach the waste stream from this source.
Waste wash solvents generally have higher boiling points and similar
solvency to those used in the paint. Waste wash solvent is often retained
and reused in later batches or is reclaimed by distillation or sedimentation
on site. It may be sent to an outside contractor for processing and the
recycled solvent is returned to the plant for reuse. Waste wash solvents are
also incinerated and some are placed in drums that are landfilled.
A-16
-------
Equipment used for water-thinned paints is cleaned with water and
sometimes with detergent. The wash water is settled, used as a thinner for
later batches of the same type of paint or, where acceptable, released to
the muncipal sewer system. Wash water from very dark colors, experimental,
or spoiled batches is usually placed in drums that are landfilled.
The potentially hazardous materials in paints include: inorganic metals
such as arsenic, beryllium, cadmium, chromium, copper, cobalt, lead, mercury,
selenium, asbestos, cyanides, and organic compounds, such as halogenated
hydrocarbons and pesticides (WAPORA, 1975).
Of the total estimated waste stream of 389,000 metric tons generated by
the paint and coatings industry, 24.6% is potentially hazardous, 3.6% is
hazardous solvents, and 0.2% is toxic chemical compounds. A detailed list of
waste components and quantities is available in the reference by WAPORA, Inc.
(1975). The organic constituent of the solvent can be particularly aggres-
sive to liners based on asphalt, polymers, and, in some cases, clay soils.
Pesticide Industry
The diverse nature of the pesticide industry and the wide distribution
of the products make it difficult to analyze and assess the pollutional
impact of specific active ingredients and their finished formulations. For
example, there were some 24,000 different formulations available from 139
manufacturers and 5,660 formulators as of February 1976. Over 50,000 dif-
ferent products are said to have been registered by the EPA. Each company
that markets a given formulation of finished pesticide must have a registered
label for it. Over 3,500 companies hold federal registrations for one or
more products. In addition, many pesticides are registered for intrastate
sale only; an estimated 2,000 pesticidal products are registered in Cali-
fornia alone (Wilkinson et al, 1978).
Many pesticide wastes are aqueous solutions or suspensions of organic
and halogenated organic compounds. Some biocide wastes are generated in the
production of: Dieldrin, Methylparathion, Dioxin, Aldrin, Chlordane, ODD,
DDT, 2,4-D, Endrin, Guthion, Heptachlor, and Lindane. Inorganic based wastes
result from the production of arsenic, arsenate, and mercurial compounds.
Thallium and thallium sulfate are found in rodenticide wastes (EPA, 1974a).
Pesticide wastes result largely from the periodic cleaning of formu-
lation lines, filling equipment, spills, area washdown, drum washing, air
pollution control devices, and area runoff. Wash waters and steam condens-
ates from cleaning operations are the sources of liquid waste from the
formulation lines and filling equipment. Steam cleaning condensates and
rinse waters from other processing units such as the mix tanks, drum washers,
and air pollution control equipment are also sources of pesticide wastes.
The scrubber waters themselves are a waste stream with area washdown, leaks,
and spills making up the remaining principal sources.
A-17
-------
The principal constituents of wastewaters from the pesticide industry
are dissolved organics, suspended solids, dissolved inorganic solids, and
variable pH. As stated above, the great variety of manufactured end products
effectively precludes the presentation of a "general" waste composition chart
or table. Again, it is the water and the dissolved constituents that may be
aggressive toward liner materials.
Because of the great range of sizes of pesticide manufacturing plants,
it is plausible to expect the following developments to occur with respect
to the disposal of generated wastes. For the small generator, the produced
waste, due to small total volume and small relative volume, might be accepted
into a municipal wastewater management system. In such an instance, the
pollution impact, if discernible, would be minor. For the large generator,
the facility would probably have its own wastewater pretreatment or treatment
system; in this case, the waste would most likely be partially treated, then
concentrated. The concentrated waste would be disposed of in a landfill, or
stabilized or containerized and then placed in a landfill.
Petroleum Refining Industry
Different waste streams generated by the petroleum refining industry
vary with the refining process. Highly caustic sludges result from oper-
ations including washing, sweetening, and neutralizing. Spent caustic
solutions are discharged from alkylation, and isomerization units, and low
pressure gas (LPG) treating processes. The waste stream is roughly 3-3.5%
NaOH by weight. Oily refinery sludges contain sand, silt, heavy metals, and
an array of organic compounds in addition to oil and water. The oil content
of such wastes ranges from 1-82% by weight. Table A-10 presents concentr-
ations and quantities of several wastes resulting from refining processes.
The oils, organics, high pH, and high ion concentrations may all be
harmful to landfill or disposal site liners. Compatibility studies should be
made before installing liners for this class of waste (Landreth, 1978).
Pharmaceutical Industry
Wastes generated by the pharmaceutical industry include chemically and
biologically derived components. Many biological wastes may be treated by
standard wastewater treatment methods, others are incinerated or landfilled.
Wastes containing heavy metals, Cr, Zn, Hg, etc. are produced in limited
quantities. The metals are recovered from these wastes and the residues are
landfilled under carefully controlled conditions. Solvents are recycled or
incinerated. Nonhazardous solid wastes which include biological sludge
from wastewater treatment, aluminum hydroxide, magnesium, and sodium salts
(McMahan et al, 1975) are usually landfilled.
The major waste producing processes are extraction and concentration
(product by product), and equipment washings. See Table A-ll for raw waste
sources and constituents. Biological wastes result from the production of
vaccines, serums, and other products derived or extracted from plant and
A-18
-------
TABLE A-10. RANGES OF CONCENTRATIONS AND TOTAL QUANTITIES FOR REFINERY SOLID WASTE SOURCES
(AH Values in Milligram Per Kilogram Except Where Noted)
Sludge from
clarified once
through cooling
Parameters water
Phenols
Cyanide
Selenium (Se)
Arsenic (As)
Mercury 'Hg)
Beryllium (Be)
Vanadium (V)
Chromium (Cr)
Cobalt (Co)
Nickel (Ni)
Copper (Cu)
Zinc (Zn)
Silver (Ag)
Cadmium (Cd)
Lead (Pb)
Molybdenum (Mo)
Ammonium
Salts (as NH4+)
Benz-a-pyrene
Oil (wt., %)
Total weight
Metric tons/year
0.0-2.1
0.01-0.74
0.1-1.7
0.1-18
0.42-1.34
0.013-0.63
15-57
16.6-103
5.5-11.2
20.5-39
56-180
93-233
0.84-1.3
0-1.0
17.2-138
0.5-33
0.01-13
0-1.8
0.24-17.0
9.7-18.0
Exchange
bundle
clearing
sludge
8-18.5
0.0004-3.3
2.4-52
10.2-11
0.14-3.6
0.05-0.34
0.7-50
310-311
0.2-30
61-170
67-75
91-297
Trace
1.0-1.5
0.5-155
1.0-12
5-11
0.7-3.6
8-13
0.4-1.0
Slop oil
emulsion
solids
5.7-68
0-4.6
0.1-6.7
2.5-23.5
0-12.2
0-0.5
0.12-75
0.1-13?5
0.1-82.5
2.5-288
8.5-111.5
60-656
0-20.1
0.025-0.19
0.25-380
0.25-30
0-44
0-0.01
23-62
1.4-29.2
Cooling
tower
sludge
0.6-7.0
0-14
0-2.4
0.7-21
0-0.1
Trace
0.12-42
181-1750
0.38-7
0.25-50
49-363
118-1,100
0.01-1.6
0.06-0.6
1.2-89
0.25-2.5
0.07-14
0-0.8
0.07-4.0
0.1-0.13
API/Prfmary
clarifier-
separator
bottom
3.8-156.7
0-43.8
0-7.6
0.1-32
0.04-7.2
0-0.43
0.5-48.5
0.1-6790
0.1-26.2
0.25-150.4
2.5-550
25-6,596
0.05-3
0.024-2.0
0.25-83
0.25-60
0.05-24
0-3.7
3.0-51.3
0.3-45
Dissolved air
flotation
float
3.0-210
0.01-1.1
0.1-4.2
0.1-10.5
0.07-0.89
0-0.25
0.05-0.1
2.8-260
0.13-85.2
0.025-15
0.05-21.3
10-1,825
0-2.8
0-0.5
2.3-1,320
0.025-2.5
8.7-52
0-1.75
2.4-16.9
13.6-31.0
Kerosene
filter clays
2.0-25.2
Trace
0.01-26.1
0.09-14
0-0.05
0.025-0.35
13.2-42
0.9-25.8
0.4-2.3
0.025-15
0.4-12,328
6.6-35
0.02-0.7
0.19-0.4
4.25-12
0.012-8.8
ca 0.01
1.7-1.8
0.7-5.6
0.79-127
Lube oil
filter clays
0.05-6.4
0.01-0.22
0 1-2.1
0.05-1.4
0.04-0.33
0.025-0.5
0.5-65
1.3-45
- 1.3-5
0.25-22
0.5-8.0
0.5-115
0.013-1.0
0.025-1.5
0.25-2.3
0.025-0.05
2-4
0.02-0.2
ca.3.9
102-682
Waste
biosludge
1.7-10.2
0-19.5
0.01-5.4
1.0-0.6
0-1.28
Trace
0.12-5
0.05-475
0.05-1.4
0.013-11.3
1.5-11.5
3.3-225
0.1-0.5
0.16-0.54
1.2-17
0.25-2.5
28-30
Trace
0.01-0.53
1.8-38.5
Continued . . .
-------
TABLE A-10. (CONTINUED)
Parameters
Phenols
Cyanide
Selenium (Se)
Arsenic (As)
Mercury (Hg)
Beryllium (Be)
Vanadium (V)
Chromium (Cr)
Cobalt (Co)
3> Nickel (N1)
^ Copper (Cu)
O Zinc (Zn)
Silver (Ag)
Cadmium (Cd)
Lead (Pb)
Molybdenum (Mo)
Ammonium
Salts (as NH4+)
Benz-a-pyrene
Oil (wt., X)
Coke
fines
0.4-2.7
Trace
0.01-1.6
0.2-10.8
0-0.2
0-0.2
400-3,500
0.02-7.5
0.2-9.2
350-2,200
3.5-5.0
0.2-20
0.01-3.0
0.015-2
0.5-29
0.1-2.5
No value
Trace
0-1.3
Silt from
Storm water
runoff
6.3-13.3
0.48-0.95
1.1-2.2
1.0-10
0.23-0.36
Trace
25-112
32.5-644
11.0-11.3
30-129
14.8-41.8
60-396
0.4-0.6
0.1-0.4
20.5-86
6.3-7.5
1.0
0.03-2.5
2.2-5.5
Leaded
tank
bottoms
2.1-250
Trace
0.1-3.1
63-455
0.11-0.94
Trace
1.0-9.8
9.0-13.7
26.5-71
235-392
110-172
1190-17,000
0.05-1.7
4.5-8.1
158-1,100
0.5-118
No value
0.02-0.4
18.9-21
Non -leaded
product tank
bottoms
1.7-1.8
0-14.7
1.5-22.4
Trace
0.41-0.04
0.025-0.49
9.1-34.6
12.7-13.1
5.9-8.2
12.4-41
6.2-164
29.7-541
0.5-0.7
0.25-0.4
12.1-37.3
0.25-18.2
0.2
0.3-0.9
45.1-83.2
Neutralized HF
alkylation
sludge (CaFj)
3.2-15.4
0.21-4.6
0.1-1.7
0.05-4.5
0.05-0.09
0.012-0.13
0.25-5
0.75-5
0.3-0.7
7.4-103
2.5-26
7.5-8.6
0.12-0.25
0.012-0.12
4.5-9.6
Trace
Trace
No value
6.7-7.1
Crude
tank
bottoms
6.1-37.8
0.01-0.04
5.8-53
5.8-53
0.07-1.53
Trace
0.5-62
1.9-75
3.8-37
12.8-125
18.5-194
22.8-425
0.03-1.3
0.025-0.42
10.9-258
0.025-95
2.0
0-0.6
21-83.6
Spent line
from boiler
feedwater
treatment
0.05-3.6
0-1.28
0.01-9.2
0.01-2.3
0-0.5
Trace
0-31.6
0.025-27.9
0-1.3
0.13-26.2
0.22-63.2
2.0-70
0.05-0.7
0-1.3
0.01-7.3
0-0.05
Trace
Trace
0.04-0.5
Fluid catalytic
cracker catalyst
fines
0.3-10.5
0.01-1.44
0.01-1.4
0.05-4.0
0-0.16
0.025-1.4
74.4-1,724
12.3-19
0.25-37
47.5-950
4.1-336
19-170
0.5-8.0
0-0.5
10-274
0.5-21
No value
0-1.0
0.01-0.8
Total Weight
Metric tons/year
0.06-4.2
2.7
0.2-1.3
34.7-77
28-67
0.14-0.26
28.5-214.7
Source: Stewart (1978).
0.65-23.6
-------
I
no
TABLE A-ll. RAW WASTE CONSTITUENTS FROM THE PHARMACEUTICAL INDUSTRY
(g/kg Production)
Area or Process
Fermentation
Biological products and
natural extractive man-
facturing
Chemical synthesis
Formulation
Research
TDS
5.990
895
1.060
11.3
1.33
N03-N
4.68
0.02
0.20
0.053
Trace
Total
P
22.0
7.3
7.83
0.15
0.23
Oil
and
grease
413
3.62
21.6
0.78
...
Cl
1.260
211
104
2.51
0.94
S04
274
277
203
0.52
1.27
Total
hard-
Sulfide ness Ca
294 123
36.4
61.6 15.2
0.007 5.82 1.01
Mg Cu
30 0.005
0.12
5.68 0.002
0.001
• • • * • •
Phenol
0.15
0.073
0.16
...
* * •
Source: Riley (1974).
-------
animal sources. Fermentation and chemical synthesis wastes resulting from
this industry frequently are a mixture of aqueous, organic, and inorganic
constituents.
Thus, waste-liner compatibility studies are essential before lining a
disposal site for this complex type of waste.
Pulp and Paper Industry
The companies that make up the pulp and paper industry are large,
diverse corporations that produce pulp, paper, and paperboard. The activ-
ities of this industry that produce wastes include chemical wood pulping,
wastepaper pulping, paper production, de-inking of recycled paper, paperboard
production, electricity production, and wastepaper reclamation. The waste
streams that are associated with these activities are wastewater-treatment
sludge, bark and hog fuel wastes, coal and bark ash, and wastepaper recla-
mation wastes. Table A-12 presents analyses of various sludges that are
generated by the pulp and paper industry.
TABLE A-12. CHEMICAL ANALYSIS OF PRIMARY AM) SECONDARY TREATMEII1 SLUDGES FROM THE PULP AND PAPER INDUSTRY
Constituent3
Water (I)
Solids (I)
Ash (*)
COD
Phenol
PCB
Otl gnd grease
Total nitrogen
Aluminum
Cadmium
Calcium
Chloride
Chromium
Copper
Iron
Lead
Magnesium
Manganese
Nickel
Phosphorous
Potassium
Sodium
Sulfate
Zinc
Primary and secondary
sludge from semi-
chemical pulping
90-96
4-10
1-2.5
60,000-120,000
5
<13
1
1,400
• • •
1.5
4,000-15,000
• • •
...
NDB
• • •
120
. • •
Z50
25
• • •
1,600
1,400
120
260
De-inking sludge Pretreatment Board Combined primary
11 (recycled De-inking sludge from mill and
paper) sludge 12 paper coating sludge secondary sludge
77.06
22 4
21,300
32
4,390
332
86
14
. . .
4oo,ono
100, 0(
20 180
330
538 1,500 200,
32 1,300
1,170
16
2.3 8 3,
310
114
146
0.03
0
40
60
40
, .
.
.
.
.
4
.
.
'79
62
2,400
.
.
,
4
.
6
.
.
6
.
.
380 47
...
1,146
52
2
...
...
...
151 300 4,000 350 397
Mn ppm unless otherwise noted.
t>ND • none detected.
Source: Energy Resources Company (1979) and EPA (1979).
The pulping processes can be classified into chemical and mechanical
processes However, it is the chemical pulping operations that generate the
hazardous waste streams through the use of chemicals to separate the fibers
from the lignin in the wood. The kraft or sulfate pulping process generates
sludges high in chromium, lead, and sodium, as shown in Table A-12. Fortun-
ately, a large proportion of the plants using this process recycle many of
their wastes, including the burning of the lignin as fuel.
A-22
-------
Wastewater treatment sludges arise from primary treatment such as
settling, filtration and flotation, and secondary treatment in activated
sludge and aerated lagoons. The concentration of specific pollutants may
vary widely, depending upon the fibers and processes used.
Most of the pulping plants produce their own electricity from coal, oil,
and bark. The bark ashes that are generated contain a low content of toxic
metals. The coal ashes are similar to those discussed under the electric
power industry.
Rubber and Plastics Industry
The rubber and plastics industry includes the production and manufacture
of several types of natural and synthetic polymers. The properties and con-
stituents of environmental concern in the process waste streams are:
Alkalinity Aluminum
Color Antimony
Cyanides Cadmium
Dissolved solids Chromium
(principally inorganic chemicals) Cobalt
Fluorides Copper
Nitrogenous compounds Iron
(organics, amines, and nitrates) Lead
Numerous organics chemicals Magnesium
Oils and greases Manganese
pH Mercury
Phenolic compounds Molybdenum
Phosphates Nickel
Sulfides Vanadium
Temperature Zinc
Turbidity
The major pollutants in the wastewater from the rubber products industry
are oil, grease, suspended solids, and extreme pH. The synthetic rubber
industry has a wastewater of high COD and BOD contents; heavy metals, cya-
nides, and phenols are usually present in less than 0.1 mg/L concentrations
(Riley, 1974). The oils, organics, and metal ions are all potentially
damaging to various lining materials (Landreth, 1978). Concentrations of
individual wastewater contaminants are frequently not reported, but the waste
stream in general is characterized by COD, 8005, TSS, TDS, and TOC (Becker,
1974 and 1975).
Soap and Detergent Industry
Soap manufacturing produces wastes high in fatty acids, zinc, alkali
earth salts, and caustic soda. Glycerine is formed as a by-product of soap
production but much of this is recovered and recycled. Sulfuric acid and
sulfonic acid are used in the preparation of some soaps; the pH of the wastes
generated in these processes is very low. Soap production wastes also
include alcohols and alkylbenzenes. The waste stream is generally high in
A-23
-------
COD, BOD5, IDS, acidity, oil, and grease, as indicated in the EPA publication
on soap and detergent manufacturing (Gregg, 1974), which is a good source of
additional information on the manufacturing processes, waste constituents,
and waste disposal techniques for this industry.
Soap and detergent industry waste is emphasized here due to the poten-
tial synergistic effects it may have upon a liner by creating a broader
dispersion of pollutants from mixing.
URANIUM TAILINGS
The chemical compositions of several acidic uranium tailings leachates
are presented in Table A-13 (Mitchell and Spanner, 1984). There are also
alkaline leachates (Williams, 1982).
Organic constituents in the leachate are not reported in the literature,
though trace amounts may be present. Typically, organics such as kerosene,
alkyl amine, and alcohol are used to remove uranium from the pregnant leach-
ate, but their fate in the milling process is uncertain (US NRC, 1980). Of
the organics, kerosene is probably the only organic component that could
threaten a polymeric FML at a tailings pond.
OTHER NONRADIOACTIVE WASTES
Large amounts of nonradioactive wastes are generated by two major
industries, the coal-fired electric power industry and the mining industry.
These industries generate large quantitites of wastes, some of which are
potentially hazardous and may have to be impounded in lined storage or
disposal facilities. The wastes from both industries are characterized by
their inorganic nature and trace metal content. Neither waste contains
significant organic material. In view of the magnitude and variety of the
wastes and the anticipated growth of the industries, some of the specific
wastes are described and briefly discussed in the following subsections.
Coal-Fired Electric Power Industry
The wastes produced by this industry fall into two major groups. The
first group consists of the following high-volume wastes: fly ash, bottom
ash, flue-gas desulfurization sludges and slurries, and combinations of
these. The second group consists of a variety of low-volume wastes, some of
which may be hazardous. The latter group includes:
- Air-preheater waste water.
- Coal pile drainage.
- Cooling water, once through.
- Cooling water, recirculating.
- Metal cleaning waste water: boiler, fireside; boiler, waterside.
A-24
-------
TABLE A-13. URANIUM MILL LEACHATE COMPOSITIONS3
Major
species
AT
As
Ca
Cd
Cl
Cr
Cu
F
Fe
Hg
K
Mg
Mn
Mo
Na
NH3
Ni
P
Pb
Se
Si
S04
V
Zn
pH (units)
Radionuclid
Pb-210
Po-210
U
Ra-226
Th-230
Bi-210
Highland
Millb
600
1.8
537
<0.1
97.1
2.7
2.3
2215
688
63.5
<5
343
3
30
<1
233.5
12850
8.4
1.8
es, pCi/Lf
250
250
3300
250
90,000
250
NRC Model
Millc
2000
3.5
500
0.2
300
50
5
1000
0.07
500
100
200
500
7
20
30000
0.1
80
2.0
• •
* *
• •
• •
• •
• •
EPA TRU
values0
700-1600
0.2
1.4-2.1
0.08-5
0.02-2.9
0.7-8.6
300-3000
400-700
100-210
0.3-16
0.13-1.4
0.8-2
0.1-120
• • •
• • •
• • •
• » *
• • •
• • •
• • •
• • •
Sweetwater
Milld
151-180
0.4
61-127
ND6
40-100
2.0
1.0
0.5-1.6
495-1350
0.004
1-610
124
23
0.1
100-109
1.3
0.05-0.09
<1
0.03
186-281
9312-9529
2.8-3.2
1.6-31
0.9-1.99
1541
361
5.4 (ppm)
47.99
3035
• • •
aValues in parts per million (ppm).
bGee et al (1980).
NRC (1980).
site visit.
eND = none detected.
fpico Curie per Liter.
Source: Mitchell and Spanner (1984).
A-25
-------
- Water-treatment wastes, especially brines.
- Miscellaneous wastes, such as equipment washdown, floor drainage, and
sanitary wastes.
High-Volume Wastes
High volume wastes generated by electric utilities consist of the
various types of ash produced during fuel combustion and the waste produced
from flue-gas desulfurization systems. Generally, the components of the high
volume wastes are: fly ash, which is collected from the flue gas; bottom ash
and boiler slag, which accumulate inside the boiler; and flue gas desulfuri-
zation (FGD) sludge, which is produced in the process of removing sulfur
dioxide gas from the flue gas. Fly ash is usually an extremely fine powder,
bottom ash consists of granular particles, while slag consists of fused ash
deposits.
The amounts of ash produced from a given system are primarily dependent
on coal characteristics and on ash collection efficiency. For example, most
coal in the United States has coal ash content ranging between 6 and 20
percent depending on the coal source, thus actual amounts of ash produced at
a particular site could vary by a factor of 3 to 4 for the same amount of
coal burned. The proportion of fly ash to bottom ash is dependent on coal
characteristics, coal preparation prior to combustion, and the type of boiler
furnace used. The volume of FGD sludge also varies widely, since volumes are
influenced by fuel sulfur content, the FGD process used, as well as additives
to the sludge, such as lime, limestone, or fly ash.
Large quantities of ash (fly ash and bottom ash) are produced by coal-
fired power plants with disposal by ponding (sluiced or wet ash) or by
landfilling (dry ash collection and transport). For the most part, ashes are
fine particles that do not interact with most liner materials. Table A-14
presents data on ash pond liquids. Several documents (Engineering Science,
1979; EPRI, 1979 and 1980) present excellent background information.
Flue-gas cleaning wastes include the previously mentioned fly ashes and
desulfurization sludges. As much as possible, the water in desulfurization
sludges is recovered and recycled within the process system. Flue-gas
desulfurization (FGD) sludges vary widely in composition and characteristics.
Because of the large quantities and the thixotropic nature of most unstabi-
lized FGD sludge, it could pose a significant potential for pollution.
Stabilized FGD sludge, in its many forms, is desirable because of improved
structural stability, reduced moisture content, reduced total volume, reduced
permeability, and improved handling (EPRI, 1980). The data presented in
Table A-15 show the range in values of several constituents and parameters
for three different FGD systems. Additional data and information is avail-
able (EPRI, 1979 and 1980; Leo and Rossoff, 1978).
A-26
-------
TABLE A-14. ELEMENTAL MAXIMUM CONCENTRATIONS AND OTHER
PARAMETERS IN VARIOUS WASTE STREAMS FROM COAL COMBUSTION3
Element
Al
Sb
As
Ba
Be
B
Cd
Ca
Cl
Cr
Co
Cu
F
Ge
Fe
Pb
Li
Mg
Mn
Hg
Mo
Ni
P
K
Se
Si
Ag
Na
Sr
Ta
Ti
V
Zn
Zr
TDS
TSS
Bi
S04
Fly ash
pond
8.80
0.012
0.023
0.40
0.02
24.60
0.052
180.0
14.0
0.17
• • •
0.45
1.00
• • •
6.60
0.20
0.40
20.0
0.63
0.0006
• • •
0.13
0.06
6.60
0.004
15.0
0.01
• • •
• • •
* • •
• • •
• • *
2.70
• • •
820.0
256.0
• • •
• • •
Bottom ash/
slag pond
8.00
0.012
0.015
0.3-3.0
0.01
24.60
0.025
563.0
189.0
0.023
0.70
0.14
14.85
• • •
11.0
0.08
0.08
102.0
0.49
0.006
0.49
0.20
0.23
7.00
0.05
51.0
0.02
294.0
0.80
0.02
0.02
0.02
0.16
0.07
404.0
657.0
0.20
2,300
Fly ash
overflow
5.30
0.03
0.02
0.30
0.003
1.03
0.04
• • •
2,415
0.139
• • •
0.09
10.40
0.10
2.90
• • •
• • •
156.0
0.02
0.0002
0.10
0.015
0.41
• • •
0.015
• • •
• • •
982.0
• • *
• • •
• • •
0.20
2.50
• • •
3,328
100.0
• • •
527
Ash pond
leachate
• • •
0.03
0.084
40.0
0.003
16.90
0.01
1.00
• • •
• • •
• • •
0.092
17.30
<0.10
• • •
0.024
• • •
• • •
<0.002
0.015
0.69
0.046
• • •
• • •
0.47
• • •
• • •
• • •
• • •
• • •
• • •
<0.20
0.19
• • •
• • •
• • •
• • •
• • •
aData are in mg/L.
Source: EPRI (1978, pp 94 and 95)
A-27
-------
TABLE A-15. RANGE OF CONCENTRATIONS OF CHEMICAL CONSTITUENTS IN
FGD SLUDGES FROM LIME, LIMESTONE, AND DOUBLE-ALKALI SYSTEMS
Liquor concentration,
Scrubber constituent mg/L (except pH)
Aluminum
Arsenic
Beryllium
Cadmium
Calcium
Chromium
Copper
Lead
0.03
0.004
0.002
0.004
180
0.015
0.002
0.01
- 2.0
- 1.8
- 0.18
- 0.11
- 2,600
- 0.5
- 0.56
- 0.52
Solids, mg/kg
...
0.6 -
0.05 -
0.08 -
105,000 -
10 -
8 -
0.23 -
i
52
6
4
268,000
250
76
21
Magnesium
Me rcu ry
Potassium
Selenium
Sodi um
Zinc
Chloride
Fluoride
Sulfate
Sulfite
Chemical oxygen demand
Total dissolved solids
pH
4.0 - 2,750
0.0004 - 0.07
5.9 - 100
0.0006 - 2.7
10.0 - 29,000
0.01 - 0.59
420 - 33,000
0.6 - 58
600 - 35,000
0.9 - 3,500
1 - 390
2,800 - 92,500
4.3 - 12.7
0.001 - 5
• • *
2-17
48,000
45 - 430
9,000
• • •
35,000 - 473,000
1,600 - 302,000
Source: Leo and Rossoff (1978).
A-28
-------
Low-Volume Wastes
Boiler-cleaning wastes are produced intermittently, but this waste
stream contains several components that are toxic and potentially aggressive
to liners (Engineering-Science, 1979; EPA, 1974b, p 143; EPA 1980, p 200).
These components consist of both the chemicals used in the cleaning solution
and the material removed from the heat-transfer surfaces, some of which are
shown in Table A-16. There are two main types of cleaning operations:
waterside and fireside. Waterside cleaning consists of cleaning the inside
of tubes and other boiler water passages, usually by chemical means. Fire-
side cleaning is more mechanical, consisting of high pressure nozzles di-
rected against the surfaces to be cleaned (EPA, 1974b, p 147). The cleaning
solution often contains alkalis to dissolve oil and grease, and detergents to
keep the removed material in colloidal suspension (Table A-17).
Water-treatment wastes can be classified into two categories: sludges
from clarification, softening and filter backwashing operations; and waste
brine from the several types of deionization processes. The composition of
the first category depends on the raw water quality and method of treatment.
Such sludges can usually be dewatered and the solid residue landfilled. The
supernatant water can be recycled for other in-plant uses.
Wastes from deionization processes are characterized by a high dissolved
solids concentration as shown in Table A-18. Waste brines from the regen-
eration of ion-exchange resins can also be highly acidic or alkaline de-
pending upon the exchange resin being used. Such water is often neutralized
and treated for suspended solids removal for subsequent use in other in-plant
operations which can tolerate low quality water (EPA, 1974b, p 132; EPA
1980, p 177).
Recirculating cooling wastewater or cooling tower blowdown is the bleed
stream from the recirculation water cooling system. The cooling tower
blowdown contains various chemical additives to prevent scale formation,
corrosion and biological fouling of surfaces. The blowdown is relatively
high in total dissolved solids, usually several times the concentration of
the feedwater. The potential for pollutants in blowdown is high, thus most
blowdown waters are ponded. In some cases, the blowdown water is used as
feedwater or make up water for sluicing ashes from boilers or for sulfur
dioxide scrubbing solution (EPA, 1974b, p 115; EPA 1980, p 44).
Wastes such as once-through cooling water and coal pile runoff, which do
not generally discharge to lined ponds are not discussed in this document.
Once-through cooling water is usually discharged to a receiving water body,
coal pile runoff occurs only occasionally and its character is dependent on
the type of coal, and miscellaneous wastes are generally discharged to a
municipal wastewater treatment plant.
Mining and Refining Industries
The selection of specific process and waste streams for discussion
reflects, in part, the available information and the relative importance of
A-29
-------
TABLE A-16. COMPOSITION OF BOILER SLOWDOWN
Parameter Concentration, mg/L
Conventional measures of pollution
pH 8.3 - 12.Oa
Total solids 125 - 1,407
Total suspended solids 2.7 - 31
Total dissolved solids 1.08 - 11.7
BOD5 10 - 1,405
COD 2.0 - 157
Hydroxide alkalinity 10 - 100
Oil and grease 1 - 14.8
Major chemical constituents
Phosphate, total 1.5 - 50
Ammonia 0.0 - 2.0
Cyanide, total 0.005 - 0.014
Trace metals
Chromium, total ca 0.02
Chromium+6 0.005 - 0.009
Copper 0.02 - 0.19
Iron 0.03 - 1.40
Nickel ca 0.030
Zinc 0.01 - 0.05
apH unit.
Source: EPRI (1978, p 58).
TABLE A-17. FIRESIDE WASTEWATER CHARACTERISTICS
Concentration,
mg/L
Constituent
Total chromium
Hexavalent chromium
Zinc
Nickel
Copper
Aluminum
Iron
Manganese
Sulfate
TDS
TSS
Oil and grease
Maximum
15
<1.0
40
900
250
21
14,000
40
10,000
50,000
25,000
Virtually
Average
1.5
0.02
4.0
70
6.0
2.0
2,500
3.5
1,000
5,000
250
absent
Source: EPA (1980, p 213).
A-30
-------
TABLE A-18. ION-EXCHANGE REGENERATION WASTES
Parameter
pH, units (122 entries)
Suspended solids,
mg/L (88 entries)
Dissolved solids,
mg/L (39 entries)
Oil and grease,
mg/L (29 entries)
Mean
value
6.15
44
6,057
6.0
Minimum
value
1.7
3.0
1,894
0.13
Maximum
value
10.6
305
9,645
22
Source: EPA (1980, p 187).
the specific streams with respect to future liner usage. There are other
factors such as total pollution potential, which were also considered.
Tables A-19 and A-20 present estimates of solid waste production in mining
industry segments, metals, and nonmetals (except coal), respectively. The
columns on tailings indicate the portion of solid waste that is most likely
to need lined impoundments. It is important to note that the data presented
does not include the liquid component of tailings generation.
Mining process and waste liquids are generally highly complex materials
usually containing water and a wide range of inorganic and organic dissolved
constituents. Residues of the reagents used in froth flotation of ores to
recover the valuable minerals and found in the aqueous portion of the tail-
ing is shown in Table A-21. Most of the organics, such as hydrocarbons,
alcohols, and ethers that remain in the tailings water evaporate, decompose,
or biodegrade. The inorganics generally are in low concentrations (Baker and
Bhappu, 1974, p 77).
Individually, most of the constituents of mining process and waste
liquids are well characterized as to their toxicity and pollution potential.
The difficulty with these liquids is that they are complex blends of com-
ponents that can act synergistically and be toxic and affect lining materials
in a variety of ways different from individual constituents. Some liquids
can also be highly concentrated and relatively simple. Analytical capabil-
ities have developed greatly in recent years; therefore, an accurate com-
positional analysis can generally be made of any given liquid. The fluid
must be characterized to determine its major constituents.
A-31
-------
TABLE A-19. ANNUAL SOLID WASTE PRODUCTION STATISTICS AT SURFACE
AND UNDERGROUND MINES3 - METALS
(In Thousand Short Tons)
Industry segment
Bauxite
Copper
Gold
Iron
Lead
Molybdenum
Silver
Tungsten
Uranium
Zinc
Otherd
Total
Mine
wasteb
11,500
378,000
11,800
277,000
2,270
13,100
2,010
210
306,000
1,270
17,000
1,020,000
Tailings0
1,400
260,000
5,400
175,000
8,900
30,400
1,900
1,750
16,200
6,700
e
508,000
Total
13,000
638,000
17,200
452,000
11,200
43,500
3,910
1,960
322,000
7,970
17,000
1,510,000
Percent
of total
for all
non-coal
minerals
<1
29
1
20
<1
2
<1
<1
14
<1
1
68
aBased on data obtained from 1978-79 Minerals Yearbook, U.S. Bureau
of Mines.
^Includes overburden from surface mining operations and waste dis-
carded on the surface from underground mining operations.
cEstimated by PEDCO from data in the 1978-79 Minerals Yearbook.
dAntimony, beryllium, manganiferrous ore, mercury, nickel, rare earth
metals, tin, and vanadium.
Quantitative information on these wastes are not compiled since rel-
atively insignificant amounts are generated.
Source: PEDCO (1981).
A-32
-------
TABLE A-20. ANNUAL SOLID WASTE PRODUCTION STATISTICS AT SURFACE
AND UNDERGROUND MINES^ - NONMETALS
(In Thousand Short Tons)
Industry segment
Asbestos
Clays
Diatomite
Feldspar
Gypsum
Mica (scrap)
Perlite
Phosphate rock
Potassium salts
Pumice
Salt
Sand and gravel
Sodium carbonate
(natural )
Stone:
Crushed or broken
Dimension
Talc, soapstone,
pyrophyl lite
Total
Mine
waste'3
4,150
43,000
d
192
2,700
467
107
420,000
163
108
d
d
322
82,400
1,620
1,460
572,000
Tailings0
2,180
0
d
920
700
1,310
294
136,000
17,200
210
1,100
6,000
5,080
0
2,830
420
174,000
Total
6,330
43,000
d
1,110
3,400
1,780
401
556,000
17,400
318
1,100
6,000
5,410
82,400
4,450
1,880
724,000
Percent
of total
for all
non-coal
minerals
<1
2
d
<1
<1
<1
<1
25
<1
<1
<1
<1
<1
4
<1
<1
32
aBased on data obtained from 1978-79 Minerals Yearbook, U.S. Bureau
of Mines.
^Includes overburden from surface mining operations and waste
discarded on the surface from underground mining operations.
cEstimated by PEDCO from data in the 1978-79 Minerals Yearbook.
^Quantitative information on these wastes are not compiled since
relatively insignificant amounts are generated.
Source: PEDCO (1981).
A-33
-------
TABLE A-Z1. COMMON FLOTATION REAGENTS USED IN THE RECOVERY OF MINERALS FROM ORES
Reagent
type and name
Collectors
Xanthate
Thiophosphates
Fatty acids
Sulfonates and
sul fates
Amines
Fuel oils
Frothers
Pine oil
Dow froth
MIBC
Conditioners
Sodium sul-
fides
Phosphorous
pentasulfide
Sodium cyanide
Sodium silicate
Milk of lime
Separan
Chemical Amount
composition added
ROCSSH <0.1
(RO)2PSSH <0.1
RCOOH 0.5 to 2.0
RSOaH 0.5 to 2.0
RS04
RNH2Acetate 0.2 to 2.0
Saturated 0.1
Aromatic alcohols <0.1
Higher alcohols <0.1
Methyl isobutyl- <0.1
carbinol
Na2S, NaHS 1 to 15
P2Ss 1 to 4
NaCN 0.005 to 0.1
Na2Si03 0.2 to 1.0
Ca(OH)2 1 to 4
Polyacrylamide <0.01
Reagents distribution
Solids
Mostly complexed
Mostly complexed
Complexed with minerals and ions
Complexed with minerals and ions
Absorbed on silicates
Selectively absorbed
Carried over in froth
Carried over in froth
Carried over in froth
Selectively complexed
Selectively complexed
Mostly complexed
Mostly complexed
Mostly complexed
Mostly absorbed
Solution
Minor
Minor
Minor
Minor
Minor
Minor
Appreciable
Appreciable
Appreciable
Major
Major
Minor
Appreciable
Appreciable
Minor
Toxic species
CS2
H2P04-, HS-, H2S
Biodegradable
Biodegradable (except
Free amine*
Volatile hydrocarbons
Volatile, carcinogeni
cyclic)
c
Volatile, biodegradable
Volatile, biodegradable
HS-, H2S, S04-
HS-, H2S
CN-
H4Si04
OH"
Biodegradable
al)nknown toxicity,
Source: Baker and
Bhappu (1974, p 77).
-------
REFERENCES
Baker, D. H. and R. B. Bhappu. 1974. Specific Environmental Problems
Associated with the Processing of Minerals. In: Extraction of Minerals
and Energy: Today's Dilemmas. R. A. Deju, ed. Ann Arbor Science Pub-
lishers, Ann Arbor, MI. 301 pp.
Becker, D. L. 1974. Development Document for Proposed Effluent Limitations
Guidelines and New Source Performance Standards for the Synthetic
Resins Segment of the Plastics and Synthetic Materials Manufacturing
Point Source Category. EPA-440/l-74/010a. U.S. Environmental Protec-
tion Agency, Washington, D.C. 247 pp.
Becker, D. L. 1975. Development Document for Effluent Limitations Guide-
lines and Standards for the Synthetic Polymer Segment of the Plastics
and Synthetic Materials Point Source Category. EPA-440/l-75-036b. U.S.
Environmental Protection Agency, Washington, D.C. 302 pp.
Breland, C. G. 1972. Landfill Stabilization with Leachate Recirculation,
Neutralization, and Sludge Seeding. CE 756A6. School of Civil Engineer-
ing, Georgia Institute of Technology. Atlanta, GA. 80 pp.
Brown, K. W., and Associates. 1980. Hazardous Waste Land Treatment. SW-874.
U.S. Environmental Protection Agency, Cincinnati, OH. 974 pp.
Brunner, D. R., and R. A. Carnes. 1974. Characteristics of Percolate of
Solid and Hazardous Wastes Deposits. Presented at AWWA (American Water
Works Association) 4th Annual Conference. Boston, MA. 23 pp.
Energy Resources Co. 1979. Economic Impact Analysis of Hazardous Waste
Management Regulations on Selected General Industries. SW-182c. Office
of Solid Waste, U.S. Environmental Protection Agency, Washington, D.C.
Engineering-Science, Inc. 1979. Evaluation of the Impacts of the Proposed
Regulations to Implement the Resource Conservation and Recovery Act on
Coal-Fired Electric Generating Facilities: Phase I Interim Report. U.S.
Department of Energy, Office of Fossil Energy, Washington, D.C.
EPA. 1973. An Environmental Assessment of Potential Gas and Leachate Prob-
lems at Land Disposal Sites. (Open-file report, restricted distribu-
tion.) U.S. Environmental Protection Agency, Washington, D.C.
EPA. 1974a. Report to Congress: Disposal of Hazardous Wastes. SW-115. U.S.
Environmental Protection Agency, Washington, D.C. 110 pp.
EPA. 1974b. Development Document for Effluent Limitations, Guidelines and
New Source Performance Standards for the Steam Electric Power Generation
Point Source Category. EPA 440/l-74-029a (NTIS PB 240 853). U.S.
Environmental Protection Agency, Washington, D.C. 865 pp.
A-35
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EPA. 1975a. Use of the Water Balance Method for Predicting Leachate Gen-
erated From Solid Waste Disposal Sites. SW-168. U.S. Environmental
Protection Agency, Washington, D.C. 40 pp.
EPA. 1975b. Development Document for Interim Final Effluent Limitations
Guidelines and New Source Performance Standards for the Significant
Organics Products Segment of the Organic Chemical Manufacturing Point
Source Category. U.S. Environmental Protection Agency. EPA-440/1-
75/045. Washington, D.C. 392 pp.
EPA. 1977. Procedures Manual for Groundwater Monitoring at Solid Waste
Disposal Facilities. EPA-530/SW-611. U.S. Environmental Protection
Agency, Cincinnati, OH. 269 pp.
EPA. 1979. Development Document for Existing Pretreatment Standards for
the Electroplating Point Source Category. EPA 440/1-79-003. U.S.
Environmental Protection Agency, Washington, D.C. 427 pp.
EPA. 1980. Development Document for Effluent Limitations Guidelines and
Standards for the Steam Electric Point Source Category. EPA 440/1-80-
029b. U.S. Environmental Protection Agency, Washington, D.C. 597 pp.
EPA. 1986. Hazardous Waste Management System; Identification and Listing
of Hazardous Waste; Notification Requirements; Reportable Quantity
Adjustments; Proposed Rule. Federal Register 51(114):21648-21693.
[See also Federal Register 52(95):18583-18585].
EPRI. 1978. The Impact of RCRA (PL 94-580) on Utility Solid Wastes. EPRI
FP-878. Electric Power Research Institute, Palo Alto, CA. 133 pp.
EPRI. 1979. Review and Assessment of the Existing Data Base Regarding
Flue Gas Cleaning Wastes. EPRI FP-671. Electric Power Research In-
stitute, Palo Alto, CA.
EPRI. 1980. FGD Sludge Disposal Manual. 2nd ed. CS-1515. Research Project
1685-1. Electric Power Research Institute, Palo Alto, CA.
Gee, G. W., A. C. Campbell, B. E. Optiz, and D. R. Sherwood. 1980. Inter-
action of Uranium Mill Tailings Leachate with Morton Ranch Clay Liner
and Soil Mineral. In: Symposium on Uranium Mill Tailings Management,
Colorado State University, Fort Collins, CO. pp. 333-352.
Genetelli, E. J., and J. Cirello, eds. 1976. Gas and Leachate from Land-
fills: Formation, Collection, and Treatment. EPA 600/9-76-004. U.S.
Environmental Protection Agency, Cincinnati, OH. 190 pp.
Gregg, R. T. 1974. Development Document for Effluent Limitations Guidelines
and New Source Performance Standards, Soap and Detergent Manufacturing
Point Source Category. EPA-440/l-74-018a. U.S. Environmental Pro-
tection Agency, Washington, D.C. 202 pp.
A-36
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Griffin, R. A., and N. F. Shimp. 1978. Attenuation of Pollutants in Munici-
pal Landfill Leachate by Clay Minerals. EPA-600/2-78-157 (NTIS PB-287-
140). U.S. Environmental Protection Agency, Cincinnati, OH. 146 pp.
Hallowell, J. B., L. E. Vaaler, J. A. Gruklis, and C. H. Layer. 1976.
Assessment of Industrial Hazardous Waste Practices: Electroplating and
Metal Finishing Industries - Job Shops. SW-136c (NTIS PB-264-369).
U.S. Environmental Protection Agency, Washington, D.C. 190 pp.
Ham, R. K. 1975. Milled Refuse Landfill Studies at Pompano Beach, Florida.
Approx. Range, Three Cells Aged One Year. 21 pp.
Ham, R. K., K. Hekimian, S. Katten, W. J. Lockman, R. J. Lofty, D. E. McFad-
din and E. J. Daley. 1979. Recovery, Processing, and Utilization of
Gas from Sanitary Landfills. EPA-600/2-79-001. U.S. Environmental
Protection Agency, Cincinnati, OH. 133 pp.
Landreth, R. 1978. Research on Impoundment Materials. In: Annual Con-
ference on Advanced Pollution Control for the Metal Finishing Industry
(1st), Held at Lake Buena Vista, Florida on January 17-19, 1978. G. S.
Thompson, Jr., ed. EPA-600/8-78-010 (NTIS PB-282 443/1BE). U.S. En-
vironmental Protection Agency, Cincinnati, OH. 152 pp.
Leo, P. P., and J. Rossoff. 1978. Controlling SO? Emissions from Coal-
Fired Steam-Electric Generators: Solid Waste Impact. Volume II: Techni-
cal Discussion. EPA 600/7-78/0445 (NTIS PB 281 100/8bE). U.S. Environ-
mental Protection Agency, Research Triangle Park, NC. 235 pp.
McMahan, J. N., L. Cunningham, L. Woodland, and D. Lambros. 1975. Hazardous
Waste Generation, Treatment and Disposal in the Pharmaceutical Industry.
Contract No. 68-01-2684. U.S. Environmental Protection Agency, Wash-
ington, D.C. 178 pp.
Metal Finishing Guidebook and Directory. 1979. Vol. 77, #13, Metals and
Plastics Publications, Inc., Hackensack, NJ.
Mitchell, D. H., and G. E. Spanner. 1984. Field Performance Assessment of
Synthetic Liners for Uranium Tailings Ponds: A Status Report. PNL-5005.
Pacific Northwest Laboratory, Richland, WA. 60 pp.
PEDCO. 1981. Mining Industry Solid Waste - An Interim Report. Office of
Solid Waste. U.S. Environmental Protection Agency, Cincinnati, OH. 93
pp.
Phillips, N. P., and R. Murray Wells. 1974. Solid Waste Disposal. Final
Report. EPA-650/2-74-033. U.S. Environmental Protection Agency, Wash-
ington, D.C. 268 pp.
A-37
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Riley, J. E. 1974. Development Document for Effluent Limitations Guide-
lines and New Source Performance Standards for the Tire and Synthetic
Segment of the Rubber Processing Point Source Category. EPA-440/1-
74/013a (NTIS PB-238-609). U.S. Environmental Protection Agency,
Washington, D.C. 195 pp.
Steiner, R. L., A. A. Fungaroli, R. J. Schoenberger, and P. W. Purdon. 1971.
Criteria for Sanitary Landfill Development. Public Works. 102(3):77-
79.
Stewart, W. S. 1978. State-of-the-Art Study of Land Impoundment Techniques.
EPA/600-2-78-196. U.S. Environmental Protection Agency, Cincinnati,
OH. 76 pp.
U.S. Nuclear Regulatory Commission. 1980. Final Generic Environmental
Impact Statement on Uranium Milling. NUREG-0706, Vol. 1, Washington,
D.C.
WAPORA, Inc. 1975. Assessment of Industrial Hazardous Waste Practices,
Paint and Allied Products Industry, Contract Solvent Reclaiming Oper-
ations, and Factory Application of Coatings. U.S. Environmental Pro-
tection Agency, Washington, D.C. 296 pp.
Wigh, R. J. 1979. Boone County Field Site. Interim Report, Test Cells 2A,
2B, 2C, and 2D. EPA-600/2-79-058 (NTIS PB-299-689). U.S. Environmental
Protection Agency, Cincinnati, OH. 202 pp.
Wilkinson, R. R., G. L. Kelso, and F. C. Hopkins. 1978. State-of-the-Art
Report: Pesticide Disposal Research. EPA-600/2-78-183. U.S. Environ-
mental Protection Agency, Cincinnati, OH. 225 pp.
Williams, R. E. 1982. A guide to the Prevention of Groundwater Contamination
by Uranium Mill Wastes. Colorado State University, Fort Collins, Co.
173 pp.
A-38
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APPENDIX B
REPRESENTATIVE LIST OF ORGANIZATIONS IN THE LINER INDUSTRY
As of June 1988
A. POLYMERIC FLEXIBLE MEMBRANE LINERS
1. Polymer producers
2. Manufacturers of polymeric membrane sheetings
3. Fabricators of liners
4. Installing contractors
B. OTHER LINER MATERIALS
B-l
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APPENDIX B (Continued)
A. POLYMERIC FLEXIBLE MEMBRANE LINERS
1. Polymer Producers
ALLIED CHEMICAL CORPORATION
P.O. Box 53006
Baton Rouge, LA 70805
Contact:
Phone:
Patrick Snell
(504) 775-4330
CHEVRON CHEMICAL COMPANY
FM1006
Orange, TX 77630
Contact:
George L. Baker
(409) 882-2167
B.F. GOODRICH CHEMICAL COMPANY
6100 Oak Tree Blvd.
Cleveland, OH 44131
Phone: (216) 447-6000
DOW CHEMICAL CO.
2040 Dow Center
P.O. Box 1847
Midland, MI 48640
Contact: David M. Cheek
Marketing Manager
Polyethylene Group
Plastics Department
Phone: (517) 636-1000, Ext. 0151
E.I. du PONT de NEMOURS & CO., INC.
Polymer Products Department
Wilmington, DE 19898
Contact:
Phone:
Contact:
Phone:
Inquiry Handling Center
(800) 441-7111
Austin Snow
Sr. Marketing Rep. - Hytrel
Barley Mill Plaza,
Garrett Mill Building
Wilmington, DE 19898
(302) 992-3296
EXXON CHEMICAL CO.
Elastomer Technology Division
P.O. Box 45
Linden, NJ 07036
Contact: S. Alexander Banks
Phone: (201) 474-0100
MONSANTO INDUSTRIAL CHEMICALS CO.
260 Springside Drive
Akron, OH 44313
Contact: Michael A. Fath
Product Development Manager
Phone: (216) 666-4111
OCCIDENTAL CHEMICAL COMPANY
300 Berwyn Park, Suite 300
P.O. Box 1772
Berwyn, PA 19312
Contact:
Phone:
Rich Webb
(215) 251-1070
PHILLIPS CHEMICAL CO.
Bartlesville, OK 74004
Phone: (918) 661-6600
POLYSAR, LTD.
Elastomers Research and Development
Division
Vidal Street
Sarnia, Ontario
CANADA N7T 7M2
Contact: Charles McGinley
Application Development Specialist
Industrial Products Group
Phone: (519) 337-8251
SHELL CHEMICAL COMPANY
605 N. Main Street
Altamont, IL 62411
Contact:
Phone:
B-2
Larry Watkins
(618) 483-6517
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APPENDIX B (Continued)
A. POLYMERIC FLEXIBLE MEMBRANE LINERS
1. Polymer Producers
SOLTEX POLYMERS CORPORATION
P.O. Box 27328
Houston, TX 77227
Contact: Richard Koob
Marketing Manager for
Extrusion Polyethylene
Phone: (713) 522-1781
UNION CARBIDE CORPORATION
Polyolefins Division
39 Old Ridgebury Road
Danbury, CT 06817
Contact:
Phone:
Christen Rundlof
(203) 794-2050
UNIROYAL CHEMICAL CO.
Spencer Street
Naugatuck, CT 06488
Contact: Thomas L. Jablonowski
Phone: (203) 723-3205
B-3
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APPENDIX B (Continued)
A. POLYMERIC FLEXIBLE MEMBRANE LINERS
2. Manufacturers of Polymeric Membrane Sheetings
B. F. GOODRICH CO.
Engineered Rubber Products Division
500 S. Main Street
Akron, OH 44318
Contact:
Phone:
Larry Cifoni
(216) 374-3115
BURKE RUBBER CO.
2250 South Tenth Street
San Jose, CA 95112
Contact: Larry Schader, Sales Manager
Flexible Membranes
Phone: (408) 297-3500
COOLEY, INC.
50 Esten Avenue
Pawtucket, RI 02862
Contact:
Phone:
Paul Eagleston
Vice President
(401) 724-9000
DUNLOP CONSTRUCTION PRODUCTS, INC.
2055 Flavelle Blvd.
Mississauga, Ontario
CANADA L5K 1Z8
Contact:
Phone:
Robert Rayfield
(416) 823-8200
INC.
DYNAMIT NOBEL,
10 Link Drive
Rockleigh, NJ 07647
Contact: Bernard Strauss
Customer Service Rep,
Phone: (201) 767-1660
GUNDLE LINING SYSTEMS, INC.
1340 East Richey Road
Houston, TX 77073
Contact: Hal Pastner, Vice President
Phone: (713) 443-8564 (Texas)
(800) 435-2008 (National)
LORD CORPORATION
Film Products Division
2000 W. Grandview Blvd.
P.O. Box 10038
Erie, PA 16514-0038
Contact: G. J. Bartko
Phone: (814) 868-3611, Ext. 3278
NATIONAL SEAL CO.
1255 Monmouth Blvd.
Galesburg, IL 61402-1448
Contact:
Phone:
John Hardison
Vice President
Hans Poetsch
(800) 323-3820
(312) 359-7810
OCCIDENTAL CHEMICAL CORPORATION
P.O. Box 456
Burlington, NJ 08016
Contact: Tim Kronbach
Phone: (609) 499-2300, Ext. 2207
POLY-AMERICA, INC.
2000 W. Marshall Drive
Grand Prairie, TX 75051
Contact: William C. Neal
Vice President, Marketing
Phdne: (800) 527-3322
(214) 647-4374
B-4
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APPENDIX B (Continued)
A. POLYMERIC MEMBRANE LINERS
2. Manufacturers of Polymeric Membrane Sheetings
SARNAFIL (U.S.), INC.
Canton Commerce Center
Canton, MA 02021
Contact: Marc Caputo
Phone: (617) 828-5400
SLT NORTH AMERICAN, INC.
P.O. Box 7730
The Woodlands, TX 77380
Contact: Lawarence J. Cirina
President
Phone: (713) 273-3066 (Conroe)
(713) 350-1813 (Houston)
SHELTER-RITE, INC.
Division of Seaman Corp.
P.O. Box 331
Millersburg, OH 44654
Contact: Bala Venktaraman
Vice President
Research and Development
Phone: (216) 674-2015
STEVENS ELASTOMERICS
J. P. Stevens & Co., Inc.
P.O. Box 658
Northampton, MA 01061
Contact: Arnold G. Peterson
Phone: (413) 586-8750
B-5
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APPENDIX B (Continued)
A. POLYMERIC MEMBRANE LINERS
3. Fabricators of Liners
ALASKA TENT & TARP, INC.
529 Front Street
Fairbanks, AK 99701
Contact:
Phone:
David Applebee
(907) 456-6328
COLUMBIA RESERVOIR SYSTEMS, LTD,
6814 - 6th S.E., Bay K
Calgary, Alberta
CANADA T2H2K4
Contact:
Phone:
Neil McLeod
(403) 252-9772
in USA
COLUMBIA GEO-SYSTEMS
Contact:
Phone:
Kevin Wynkoop
(303) 394-3766
ENGINEERED TEXTILE PRODUCTS
P.O. Box 7474
Mobile, AL 36607
Contact: John Robinson, President
Phone: (205) 479-6581
ENVIRONMENTAL LINERS, INC.
2009 N. Industrial Road
Cortez, CO 81321
Contact:
Phone:
Stuart Stroud
1-800-821-0531
(303) 565-9540
ENVIRONMENTAL PROTECTION, INC.
Ill West Park Drive
Kalkaska, MI 49646
Contact: Fred Rohe, President
Phone: (800) 345-4637
(616) 587-9208
ENVIRONETICS, INC.
9824 Industrial Drive
Bridgeview, IL 60455
Contact: Ray Winters, President
Phone: (312) 585-6000
LAYFIELD PLASTICS
14604 115A Avenue
Edmonton, Alberta
CANADA T5M3C5
Contact: Imre Bogovics
Phone: (403) 453-6731
MIDESSA LINING COMPANY
5203 West 42nd, Route 4
Odessa, TX 79764
Contact: Rubin Velasquez
Phone: (915) 381-2077
MPC CONTAINMENT SYSTEMS, LTD.
4834 South Oakley
Chicago, IL 60609
Contact: Jack Moreland
Vice President, Engineering
Phone: (800) 621-0146
PALCO LININGS, INC. (WEST)
7571 Santa Rita Circle
P.O. Box 919
Stanton, CA 90680
Contact: Richard Cain, President
Phone: (714) 898-0867
PALCO LININGS, INC. (EAST)
2500-B Hamilton Road
South Plainfield, NJ 07080
Contact: John Kursten
Phone: (201) 753-6262
B-6
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APPENDIX B (Continued)
A. POLYMERIC MEMBRANE LINERS
3. Fabricators of Liners
PROTECTIVE COATINGS, INC,
1602 Birchwood Avenue
Ft. Wayne, IN 46803
Contact:
Phone:
Fred Haines
(219) 424-2900
REVERE PLASTICS
16 Industrial Avenue
Little Ferry, NJ 07643
Contact:
Phone:
Ed Smith
(201) 641-0777
SERROTT CORPORATION
P.O. Box 1519
Huntington Beach, CA 92647
Contact:
Phone:
G. M. Torres
President
(714) 848-0227
STAFF INDUSTRIES
240 Chene Street
Detroit, MI 48207
Contact: Ed Staff Sr., President
Ed Staff Jr., Vice President
Phone: (313) 259-1820
(800) 526-1368
STAFLEX CORPORATION
1501 Lana Way
Hoi lister, CA 95023
Contact: Paul Weber
Phone: (408) 637-6622
UNIT LINER COMPANY
P.O. Box 789
Shawnee, OK 74884
Contact: Russell Fregia
Phone: (405) 275-4600
WATERSAVER COMPANY, INC.
5890 East 56th Avenue
Commerce City, CO 80022
P.O. Box 16465
Denver, CO 80216
Contact: Jim Bryan
Vice President
Phone: (303) 289-1818
MANUFACTURER WHO ALSO FABRICATES
National Seal Company
B-7
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APPENDIX B (Continued)
A. POLYMERIC MEMBRANE LINERS
4. Installing Contractors
AQUILINE SYSTEMS
P.O. Box 72099
Corpus Christi, TX 78472-2099
Contact: John M. Saenz
CRESTLINE SUPPLY CORPORATION
2987 South 300 West
Salt Lake City, UT 84115
Contact: Guy Woodward, President
Phone: (801) 487-2233
GAGLE COMPANY, INC.
P.O. Box 701193
Tulsa, OK 74170
Contact: Gary Willis, Manager
Sales and Contracts
Phone: (918) 258-7078
GASTON CONTAINMENT SYSTEMS, INC.
1853 North Main Street
P.O. Box 1157
El Dorado, KS 67042
Contact:
Phone:
Larry Gaston
(316) 321-5140
GEO CON
P.O. Box 17380
Pittsburgh, PA 15235
Contact: Michael W. Bowler
Vice President
Phone: (412) 244-8200
GULF SEAL CORPORATION
601 Jefferson Street, Suite 535
Houston, TX 77002
Contact: William J. Way
Vice President &
General Manager
Phone: (713) 759-0861
MCKITTRICK MUD CO.
P.O. Box 3343
Bakersfield, CA 93305
Contact: Gary Leary
Phone: (805) 325-5013
MWM CONTRACTING CORPORATION
2359 Avon Industrial Division
Rochester Hills, MI 48057
Contact: Jim Green
Phone: (313) 852-8910
MWM CONTRACTING CORPORATION
100 Sun Eagle Drive
Mount Dora, FL 32757
Contact: Raymond Wild
Phone: (904) 383-7148
NILEX, USA, INC.
10 Arapahoe Corporation Park
12503 E. Euclid Drive
Englewood, CO 80111
Contact: Morris Jett, Vice President
Phone: (303) 790-7222
NORTHWEST LININGS, INC.
20222 87th Avenue South
Kent, WA 98032
Contact: Rod Newton
Phone: (206) 872-0244
PLASTI-STEEL, INC.
1999 Amidon, Suite 208
Wichta, KS 67203
Contact: M. C. Green, President
Phone: (316) 832-0624
B-8
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APPENDIX B (Continued)
A. POLYMERIC MEMBRANE LINERS
4. Installing Contractors
FABRICATORS WHO ALSO INSTALL
Alaska Tent & Tarp, Inc.
Columbia Reservoir Systems, Ltd.
Environmental Liners, Inc.
Environmental Protection, Inc.
Layfield Plastics
McKittrick Mud Company
Midessa Lining Company
National Seal Company
Palco Linings, Inc.
Serrot Corporation
Staff Industries
Staflex Corporation
Unit Liner Company
Watersaver Company
MANUFACTURERS UHO ALSO INSTALL
Gundle Lining Systems, Inc.
Schlegel Lining Technology, Inc.
B-9
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APPENDIX B (Continued)
B. OTHER LINER MATERIALS
THE ASPHALT INSTITUTE
Asphalt Institute Building
College Park, MD 20740
Contact:
Phone:
E. R. Harrigan
(301) 277-2458
GACO WESTERN, INC.
P.O. Box 88698
Seattle, WA 98188
Contact: Rodney E. Bechtel
Sales Manager
Phone: (206) 575-0450
MICHELLE CORPORATION
Division of Weychem Canada Limited
P.O. Box 4794
Charleston Heights, SC 29405
Contact: F. Weyrich, President
Phone: (803) 554-4033
NATIONAL LIME ASSOCIATION
3601 N. Fairfax Drive
Arlington, VA 22201
Phone: (703) 243-5463
PHILLIPS PETROLEUM COMPANY
Commercial Development Division
Bartlesville, OK 74004
Contact: Floyd H. Holland
Phone: (918) 661-6428
PORTLAND CEMENT ASSOCIATION
Old Orchard Road
Skokie, IL 60076
Phone: (312) 066-6200
RELIANCE UNIVERSAL, INC.
P.O. Box 1113
Houston, TX 77251
Contact: John Owen
Phone: (713) 672-6641
(206) 293-3433
B-10
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APPENDIX C
POLYMERS FORMERLY USED IN MANUFACTURE OF FMLS
This appendix presents information on polymers that are at present no
longer being used in the manufacture of FMLs. The polymers discussed in
this appendix include:
- Butyl rubber.
- Elasticized polyolefin.
- Epichlorohydrin rubbers.
- Ethylene-propylene rubber.
- Neoprene.
- Nitrile rubber.
- Thermoplastic elastomers.
Manufacture of FMLs based on these polymers was discontinued for a variety
of reasons, including both technical and economic. In general, the manu-
facture of FMLs based on vulcanized polymers was discontinued because of
difficulties in developing an adequate system for seamig vulcanized FMLs in
the field.
C.I Butyl Rubber
The first synthetic FMLs were based on butyl rubber [isobutylene-
isoprene rubber (IIR)], and were used for irrigation and water impoundment;
some of these have been in this type of service for about 30 years (Smith,
1980). Butyl rubber is a copolymer of isobutylene (97%), with small amounts
of isoprene in the polymer chain to furnish chemically active sites for
vulcanization or crosslinking. Relevant properties of butyl rubber vul-
canizates that have been used as liner materials for water and waste storage,
and waste disposal include:
- Low gas and water vapor permeability.
- Thermal stability.
C-l
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- Moderate resistance to ozone and weathering.
- Moderate chemical and moisture resistance.
- Resistance to animal and vegetable oils and fats.
Butyl rubber is usually compounded with fillers and some oil, and vulcanized
with sulfur. Vulcanizates of butyl rubber swell substantially when exposed
to hydrocarbon solvents and petroleum oils, but are only slightly affected
by oxygenated solvents and other polar liquids. These materials have good
resistance to mineral acids, high tolerance for extremes in temperature,
retention of flexibility throughout service life, good tensile strength, and
desirable elongation qualities.
Butyl rubber FMLs were manufactured in both fabric-reinforced and
unreinforced versions. They were difficult to seam and repair in the field
because they required special vulcanizing adhesives that could crosslink at
ambient temperatures. Because these adhesives crosslinked only slightly,
they were generally less resistant to the service conditions than the FML
itself was.
C.2 Elasticized Polyolefin
Elasticized polyolefin (ELPO) was a blend of rubbery and crystalline
polyolefins. FMLs based on ELPO were introduced in 1975 as black, unvul-
canized, thermoplastic sheetings, which could be heat sealed with a specially
designed welder either in the field or at the factory. ELPO had a low
density (0.92) and was relatively resistant to weathering, alkalies, and
acids (Haxo et al, 1985). ELPO FMLs were manufactured by blow extrusion and
were supplied without fabric reinforcement in sheets, 20-ft wide and up to
200-ft long.
C.3 Epichlorohydrin Rubbers
Epichlorohydrin-based elastomers (CO and ECO) are saturated, high
molecular weight, aliphatic polyethers with chloromethyl side chains. The
two types available are a homopolymer and a copolymer of epichlorohydrin with
ethylene oxide. These polymers are crosslinked with a variety of reagents
that react difunctionally with the chloromethyl group, including diamines,
urea, thioureas, 2-mercaptoimidazoline, and ammonium salts.
Epichlorohydrin elastomer vulcanizates exhibit the following character-
istics that were relevant to FML performance:
- Moderate resistance to hydrocarbon solvents, fuels, and oils.
- Resistance to ozone and weathering.
- Low permeability to gases and hydrocarbon vapors.
- Thermal stability.
C-2
-------
- Good tensile and tear strengths.
Epichlorohydrin rubber has a high tolerance for extreme temperatures and
retains its flexibility at low temperatures. The homopolymer has a per-
formance range of 0° to 325°F. The copolymer shows improved low temperature
flexibility and is recommended for service from -40° to 300°F. Epichloro-
hydrin elastomers are seamed at room temperature with vulcanizing adhesives.
FMLs based on these rubbers were developed for service with nonaqueous waste
streams.
C.4 Ethylene-Propylene Rubber
Ethylene-propylene rubbers (EPDM) form a family of terpolymers of
ethylene, propylene, and a minor amount of nonconjugated diene hydrocarbon.
The diene supplies double bonds to the saturated polymer chain so that there
are chemically active sites for vulcanization. EPDM is usually vulcanized
with sulfur. EPDM FMLs were generally based on vulcanized compounds; how-
ever, thermoplastic EPDM FMLs were also available. The latter generally
featured EPDM of high molecular weight, high ethylene content, and high oil
extension. Both thermoplastic and crosslinked versions were manufactured
with and without fabric reinforcement.
FMLs based on vulcanized EPDM compounds had good resistance to weather
and ultraviolet exposure and, when compounded properly, resisted abrasion and
tear. They also tolerated a broad temperature range and maintained their
flexibility at relatively low temperatures. They had good resistance to
dilute acids, alkalies, silicates, phosphates, and brine, but were not
recommended for contact with either petroleum solvents (hydrocarbons) or
aromatic or halogenated solvents.
In fabricating field seams, vulcanized EPDM FMLs required special
adhesives that crosslinked at ambient temperature. Careful application was
necessary to assure satisfactory field seaming. These adhesives were less
resistant to service conditions than the FML itself. Thermoplastic EPDM
liners were generally seamed by thermal methods.
Because of its excellent ozone resistance, minor amounts of EPDM were
sometimes added to butyl rubber compounds to improve weather resistance.
C.5 Neoprene
Neoprene (CR) is the generic name of the synthetic rubbers that are
derived from chloroprene. These rubbers are vulcanizable, usually with metal
oxides, but also with sulfur. They closely parallel natural rubber in such
mechanical properties as flexibility and strength. Neoprene vulcanizates are
superior to natural rubber vulcanizates in their resistance to oils, weather-
ing, ozone, and ultraviolet radiation, and are generally resistant to
puncture, abrasion, and mechanical damage. Neoprene FMLs were used primarily
to impound liquids containing traces of hydrocarbons. They also reportly
performed satisfactorily in the containment of certain combinations of oils
and acids which other materials, available at that time, could not contain
C-3
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adequately over long periods of time. Neoprene sheeting used as FMLs was
vulcanized; seaming was relatively difficult because cements and adhesives
that cure at ambient temperatures had to be used.
C.6 Nitrile Rubber
Nitrile rubbers (NBR) make up a family of copolymers of butadiene and 18
to 50% acrylonitrile. The principal feature of these copolymers is their
oil resistance, which increases with increasing acrylonitrile content. In
most applications, nitrile rubber is compounded with plasticizers and vul-
canized; however, it is also blended with other polymers such as polystyrene,
phenolics, and PVC to produce thermoplastic compositions that range in
flexibility from rubbery compositions to hard, impact-resistant plastics.
Nitrile rubber used in the manufacture of FMLs was generally used in
blends of polymers to produce thermoplastic sheetings that were oil re-
sistant. Nitrile rubber has been mixed with PVC in amounts less than 50% to
form thermoplastic compounds in which it functions as a nonmigrating and
nonextractable plasticizer.
C.7 Thermoplastic Elastomers
Thermoplastic elastomers are a broad class of rubbery materials that
are thermoplastic, unvulcanized, and can contain some crystallinity (Walker,
1979). They include a wide variety of polymeric compositions from highly
polar materials to the nonpolar materials, such as ethylene-propylene block
polymers. It should be noted that polyester elastomers, which are thermo-
plastic elastomers, are presently being used in the manufacture of FMLs.
These are discussed in Section 4.2.2.1.3. These polymers are plastic at the
high temperatures at which they are processed and shaped. At normal ambient
temperatures, they behave much like vulcanized rubbers. Products made of
these polymers have a limited upper-temperature service range, which is
substantially above the temperatures encountered at waste disposal sites.
FMLs based on thermoplastic elastomers were heat sealed to make seams.
REFERENCES
Haxo, H. E., R. S. Haxo, N. A. Nelson, P. D. Haxo, R. M. White, and S.
Dakessian. 1985. Liner Materials Exposed to Hazardous and Toxic
Wastes. EPA-600/2-84-169. U.S. Environmental Protection Agency,
Cincinnati, OH. 256 pp.
Smith, W. S. 1980. Butyl - The Original Watersaver Elastomer. In: The
Role of Rubber in Water Conservation and Pollution Control. Proc. Henry
C. Remsberg Memorial Education Symposium, 117th meeting, Rubber Divi-
sion, American Chemical Society, May 22, 1980, Las Vegas, NV. The John
H. Gifford Memorial Library and Information Center, University of Akron,
Akron, OH. pp III-l - 111-19.
Walker, B. M. 1979. Handbook of Thermoplastic Elastomers. Van Nostrand
Reinhold, New York. 345 pp.
C-4
-------
APPENDIX D
POUCH TEST FOR PERMEABILITY OF POLYMERIC FMLS
SCOPE
This test measures the permeability of polymeric FMLs to water and to
various constituents of a waste liquid. Because of the need for narrow-width
seams in the pouches, only those FMLs that can be heat-seamed successfully
using laboratory equipment can be tested in accordance with this procedure.
(Note: Even though pouches fabricated with solvents and bodied solvents have
also been tested successfully, it is far more difficult to obtain reliable
narrow-width seams and to control the interior dimensions of a fabricated
pouch using these methods.) Whenever possible, testing an unreinforced FML
is preferred over testing a fabric-reinforced FML to avoid any potential
pinholes and leaks that could be associated with the threads of the fabric
reinforcement.
SUMMARY OF METHOD
Waste liquid is sealed in a small pouch fabricated of the FML to be
tested. This pouch is placed in a larger plastic bag containing deionized
to create a concentration gradient across the FML which results in the
movement by osmosis of water, ions and other dissolved constituents through
the pouch walls. Weight and conductivity measurements are taken periodically
to determine, respectively, the extent of movement of water into the FML and
the extent to which constituents in the waste liquid permeate through the
FML. At the end of the exposure, the pouch is dismantled and the pouch wall
material tested for physical and analytical properties.
APPLICABLE DOCUMENTS
- ASTM D297, "Methods for Rubber Products - Chemical Analysis."
- ASTM D412, "Test Methods for Rubber Properties in Tension."
- ASTM D624, "Test Method for Rubber Property - Tear Resistance."
- ASTM D638, "Test Method for Tensile Properties of Plastics."
- ASTM D882, "Test Methods for Tensile Properties of Thin Plastic
Sheeting."
D-l
-------
- ASTM D1004, "Test Method for Initial Tear Resistance of Plastic Film
and Sheeting."
- ASTM D2240, "Test Method for Rubber Property - Durometer Hardness."
- ASTM D3421, "Recommended Practice for Extraction and Analysis of
Plasticizer Mixtures from Vinyl Chloride Plastics."
- FTMS 101C, Method 2065, "Puncture Resistance and Elongation Test
(1/8-inch Radius Probe Method)."
- Matrecon Test Method 1, "Procedure for Determination of the Volatiles
of Exposed and Unexposed Membrane Liner Materials" (See Appendix G).
- Matrecon Test Method 2, "Procedure for Determination of the Extract-
ables Content of Exposed and Unexposed Membrane Lining Materials" (see
Appendix E).
EQUIPMENT AND SUPPLIES
Equipment
- Heat sealer, e.g. P.A.C. Bag Sealer Model 12 PI with long interval
timers.
- Clamp made of two 0.5-in. square steel bars 4-in. long with 0.25-in.
bolts and thumb screws located 0.5-in. from the ends.
- Wooden racks with compartments 1 x 8 x 6.5 in. deep.
- pH meter.
- Conductivity meter, e.g. Industrial Instruments Conductivity Bridge
Model RC 16B2.
- Balance, 1000 g capacity, accurate to ±0.1 g.
- Stress-strain machine suitable for measuring tensile strength,
tear resistance, and puncture resistance in accordance with the
appropriate test methods.
- Jig for measuring puncture resistance in accordance with FTMS 101C,
Method 2065.
- Apparatus for running extractables, e.g. Soxhlet extractor (ASTM
D3421) or ASTM D297 rubber extraction apparatus (see Matrecon Test
Method 2, presented in Appendix E). All glass apparatus is pre-
ferred for chlorinated solvents or for liner materials which contain
chlorine, because materials containing chlorine sometimes corrode
the tin condensers of the D297 apparatus.
D-2
-------
- Analytical balance.
- Two-inch interior diameter circular die.
- Dies for cutting tensile and tear test specimens as required.
- Individual dessicators containing calcium chloride (CaCl2).
- Ai r oven.
Supplies
- Deionized or distilled water.
- Polybutylene bags with a wall thickness of 6 to 10 mils, and with
dimensions of 8.5 x 10 inches.
- Cotton swabs.
- Medium size binder clips.
TEST SAMPLE
Each pouch requires two 7 x 7-in. squares of FML. In addition to the
material required to fabricate the pouches, sufficient material from the same
roll should be on hand to perform physical and analytical testing of the
unexposed FML. At the same time that a pouch is fabricated, a seam sample
should be fabricated using the same procedure (i.e. the same heat and dwell
time) to be used in measuring the strength of the unexposed seam. Pouch
tests of a given liner/waste liquid combination should be run in duplicate.
PROCEDURE
- Obtain a representative sample of the waste liquid. Note if waste
classifies or separates and determine the pH, electrical conductivity,
and total solids of each phase of the waste sample as necessary. A
more extensive waste analysis may also be required.
- Perform the following tests on an unexposed sample of the polymeric
FML from the same roll as the material used in fabricating the pouch.
—Volatiles, Matrecon Test Method 1 (Appendix G).
—Extractables with suitable solvent, Matrecon Test Method 2
(Appendix E).
--Tear resistance, machine and transverse directions, five speci-
mens each direction. See Table D-l for appropriate test method
and recommended speed of test.
D-3
-------
--Puncture resistance, five specimens, FTMS 101C, Method 2065.
--Tensile properties, machine and transverse directions, five
specimens each direction. See Table D-l for appropriate test
method, recommended test specimen, speed of test, and values
to be reported. The recommended test specimen for thermoplastic
and semi crystalline thermoplastic FMLs is presented in Figure
D-l.
--Hardness, Duro A (Duro D if Duro A reading is greater than 80),
ASTM D2240.
--Seam strength in peel mode, 5 specimens, ASTM D413, in 90° peel
with 1-in. wide strips at a jaw separation rate of 2 ipm. ASTM
D638 Type I specimens may be substituted for the 1-in. wide
strips if necessary to concentrate stress on the seam area.
Report the locus of break of the tested specimens. Seam testing
should be performed on a sample fabricated at the same time as
the pouch using the same heat and dwell times of the heat-seaming
apparatus.
- Cut two pieces of liner as shown in Figure D-2.
- Heat seal the two pieces of FML together leaving the neck open.
Measure the inside dimensions of the pouch to the nearest millimeter
and record the calculated area and dry weight of the pouch.
- Test the pouch for leaks by filling with deionized water. Close the
neck of the pouch with binder clips. Weigh the full pouch again
after one week to test for loss by leakage.
- If there is no leakage, empty the water out of the pouch and pour
100 g of the waste liquid into the pouch through a funnel. Close the
pouch by applying the clamp at the base of the neck. Carefully dry
the inside of the neck with cotton swabs. Heat seal the neck opening.
Remove the clamp, and record the weight of the filled pouch.
- Place the pouch in a PB bag with 600 ml of DI water. Fold the opening
of the polybutylene bag over and secure with binder clips (Figure
D-3).
- Store the assembly in a compartment of the racks so that the sealed
pouch is covered by water in the PB bag (Figure D-4).
- For testing during exposure, remove the pouch from the PB bag, blot
dry, and weigh. Measure the pH and conductivity of the water in the
outer bag.
D-4
-------
TABLE D-l. RECOMMENDATIONS FOR TENSILE AND TEAR TESTING FOR POUCH TEST
Type of Compound and
Construction3
TP
CX
FR
i
in
Tensile properties
Method
Type of specimen
Speed of test
Values to be reported
Tear resistance
Method
Type of specimen
Speed of test
ASTM D638
Special dumbbell0
20 ipm
Tensile strength, psi
Elongation at break, %
Tensile set after break, %
Stress at 100, 200, and 300%
elongation, psi
Stress at 100, 200, and 300%
elongation, psi
ASTM D1004
Die C
-------
t
1
wo
1
i
V^
^x-
\
w
T
1 n
X*"
\
Figure D-l. Die for special dumbbell. Dimensions are as follows:
W - Width of narrow section 0.25 in.
L - Length of narrow section 1.25 in.
WO - Width overall 0.625 in.
LO - Length overall 3.50 in.
G - Gage length 1.00 in.
D - Distance between grips 2.00 in.
The width of the narrow section of this specimen,
W, is the same as that of the ASTM D412 Die C dumbbell
and the ASTM D638 Type IV dumbbell. It should be
noted that these two dumbbells essentially have the
same dimensions. The length of the narrow section, L,
and the overall length, LO, of the ASTM D412 Die
C/ASTM D638 Type IV dumbbell are, respectively, 1.30
in. and 4.50 inches.
'
Open for waste 2
to be added
i
t
j
i
IL |
" B
-j
j"
7" . ^
*
II
. . "
HI
~i 1 !
II GRAIN
II DIRECTION
I'
1 «
T H
i T |
1 !
n «
L JL
"! " !
^ CV" fc.
1
7
1
Figure D-2. Pattern for cutting pieces of membrane for making
the pouch. Dotted line indicates the heat seal of
the pouch. The inside dimension of the pouch is
4.5 x 5.75 inches.
D-6
-------
OUTER BAG-
POLYBUTYLENE
DEIONIZED WATER
IN OUTER BAG
INNER POUCH-
FML UNDER TEST
WASTE OR TEST LIQUID
IN THE INNER POUCH
Figure D-3. Schematic of pouch assembly. The pouch is filled
with waste fluid and sealed at the neck. The outer
polybutylene bag, which can be easily opened, is
filled with deionized water. The water in the outer
bag is monitored for pH and conductivity; the pouch
is monitored for weight change.
Figure D-4. Pouch and auxiliary equipment for determining perme-
ability of polymeric FMLs to water and constituents
of waste liquids.
D-7
-------
- These measurements should be made weekly during the first month,
twice a month for the next five months, decreasing to once a month,
and eventually to once every two months. It is important to watch for
leaking bags and pouches.
- The exposure period should end when the increase in weight and con-
ductivity have reached a level of constant change or when the pouch
material has changed drastically. The expected exposure period is six
months to one year; longer exposures are also recommended.
- When a pouch has failed or at the end of the exposure period, dis-
mantle and test by the following procedure:
--Weigh the filled pouch before dismantling.
—Determine pH and conductivity of the water in the outer bag.
—Measure length and width between seams of pouch.
--Empty pouch and determine pH, conductivity, and weight of waste.
—Weigh the emptied pouch.
—Dismantle pouch at seams, leaving bottom seam together.
—Prepare specimens for physical tests. A suggested pattern for
cutting out specimens out of the exposed pouch is shown in Figure
D-5.
—Perform the following tests:
—Volatiles, Matrecon Test Method 1 (Appendix G).
—Extractables with the same solvent used to determine the extract-
ables of the unexposed samples, Matrecon Test Method 2 (Appendix
E).
—Tear resistance, machine and transverse direction, a minimum of
two specimens each direction. See Table D-l for appropriate test
method and recommended speed of test.
—Puncture resistance, a minimum of one specimen, FTMS 101C, Method
2065.
—Tensile properties, machine and transverse directions, a minimum
of two specimens per direction. See Table D-l for appropriate
test method, recommended test specimen, speed of test, and values
to be reported. The recommended test specimen for thermoplastic
and semi crystalline thermoplastic FMLs is presented in Figure D-l.
—Hardness, Duro A (Duro D if Duro A reading is greater than 80),
ASTM D2240.
D-8
-------
Figure D-5. Suggested pattern for cutting test specimens out of
the exposed pouch.
D-9
-------
—Seam strength in peel mode, a minimum of two specimens, ASTM
D413, in 90° peel at a jaw separation rate of 2 ipm with the
sampe type of specimen used to test the unexposed sample.
REPORT
The results of the pouch test should include:
- A description of the waste liquid and the results of the analyses.
- The properties of the unexposed FML.
- The electrical conductivity and pH of the water in the outer pouch as
a function of time.
- The change in weight of the filled pouch as a function of time.
- The pH, electrical conductivity, and change in weight of the waste
liquid in the pouch at the end of the exposure. Based on the change
in weight value, the rate of transmission of water into the pouch
should be determined in g per unit area of pouch wall material per
unit time.
- The change in weight of the empty pouch at the end of exposure.
- A summary of the properties of the exposed FML. Test values should be
reported for the following properties of the exposed FML:
- Volatiles.
- Extractables.
- Puncture resistance.
- Seam strength in peel mode.
- Percent retention values should be reported for the following prop-
erties of the exposed FML:
- Tensile properties.
- Tear resistance.
- Hardness values should be reported as a change in durometer points.
- A list of procedures used in the property testing.
- Any observations regarding the exposure of the pouch and the condition
of the pouch at the end of the exposure.
D-10
-------
APPENDIX E
PROCEDURE FOR DETERMINATION OF THE EXTRACTABLES CONTENT OF EXPOSED
AND UNEXPOSED FMLS [MATRECON TEST METHOD 2 (MTM-2) - AUGUST 1982]
Editorially Revised November 1987
SCOPE
This procedure covers the extraction of plasticizers, oils, and other
solvent-soluble constituents of polymeric FMLs with a solvent that neither
decomposes nor dissolves the polymer. Extractions are performed on specimens
from which the volatiles have been removed.
APPLICABLE TEST METHODS
This procedure generally is in accordance with ASTM D3421*, "Recommended
Practice for Extraction and Analysis of Plasticizer Mixtures from Vinyl
Chloride Plastics." See also ASTM D297, "Methods for Rubber Products--
Chemical Analysis," Sections 16-18.
SIGNIFICANCE
The extractables of a polymeric FML can consist of plasticizers, oils,
or other solvent-soluble constituents that impart or help maintain specific
properties, such as flexibility and processibility. During exposure to a
waste, leachate, or test liquid, the extractables content may be extracted
resulting in a change of properties. Another possibility is that during an
exposure the FML could absorb nonvolatilizable constituents of the liquid it
is exposed to. Measuring the extractables content is, therefore, useful for
characterizing an unexposed FML and for assessing the effect of an exposure
on an FML. The extract and the extracted FML obtained by this procedure can
be used for further analytical testing, e.g. gel chromatography, infrared
spectroscopy, ash, thermogravimetry, etc.
APPARATUS
- Aluminum weighing dishes.
*The references at the end of this appendix include the ASTM standards cited
in this appendix.
E-l
-------
- Analytical balance capable of weighing to the nearest 0.0001 gram.
- Air oven.
- Soxhlet extractor or rubber extraction apparatus*.
- Extraction thimbles.
- 500 ml flat-bottomed flask (or 400 ml thin-walled Erlenmeyer flask if
rubber extraction apparatus is used).
- Hot plate or steam plate.
- Boiling beads.
- Cotton wool.
- Aluminum foil.
REAGENTS
Table E-l lists the recommended solvents for extraction of FMLs of each
polymer type. Because FMLs can be based on polymeric alloys which are
marketed under a trade name or under the name of only one of the polymers,
this list can only be taken as a guideline for choosing a suitable solvent
for determining the extractables. Once a suitable solvent has been found, it
is important that the same solvent is used for determining the extractables
across the range of exposure periods if this method is being used to assess
the effects of an exposure.
SAMPLE SIZE
If using the Soxhlet extractor, about 5 g of a devolatil ized FML are
needed per extraction. If using the rubber extraction apparatus, about 2 g
are needed. All extractions should be run in duplicate.
PROCEDURE
- Cut the sample into cubes no larger than 0.25 in. on a side.
- Weigh sample into an aluminum weighing dish to the nearest 0.0001 g
and dry in moving air at room temperature for more than 16 hours.
*Because HC1 splits out during the extraction of PVC and CPE, the rubber
extraction apparatus may be substituted for the Soxhlet with all polymers
except PVC and CPE. An appropriate reduction in sample size and solvent
volume must be made.
E-2
-------
TABLE E-l. SUGGESTED SOLVENTS FOR EXTRACTION OF POLYMERIC FMLS
Polymer Type
Extraction Solvent
Butyl rubber
Chlorinated polyethylene
Chlorosulfonated polyethylene
Elasticized polyolefin
Epichlorhydrin rubber
Ethylene proplene rubber
Neoprene
Nitrile rubber (vulcanized)
Nitrile-modified polyvinyl chloride
Polyester elastomer
High-density polyethylene
Polyvinyl chloride
Thermoplastic olefinic elastomer
Methyl ethyl ketone
n-Heptane
Acetone
Methyl ethyl ketone
Methyl ethyl ketone or acetone
Methyl ethyl ketone
Acetone
Acetone
2:1 blend of carbon tetrachloride
and methyl alcohol
Methyl ethyl ketone
Methyl ethyl ketone
2:1 blend of carbon tetrachloride
and methyl alcohol
Methyl ethyl ketone
Place in air oven for 20 h at 105±2°C. Weigh the sample to the near-
est 0.0001 g. (Note: 2 h are acceptable for unexposed FML samples.)
Weigh the sample into a tared extraction thimble. Plug small thimbles
with a piece of cotton wool to prevent the pieces from floating out of
the thimble. (Large thimbles are tall enough to stay above the level
of the 1iquid.)
Add the necessary amount of extraction solvent to the distillation
flask (if using the thin-walled Erlenmeyer flask, the flask is to be
pre-weighed). Boiling beads are added to the 500 mL flasks to reduce
bumping.
Place the thimble in the extractor barrel, put the condenser in place,
and run the extraction a minimum of 22 hours. Aluminum foil can be
wrapped around the extractor and flask to increase the distillation
rate.
E-3
-------
- When the extraction is complete, rinse all the solvent from the
extractor barrel into the distillation flask. Evaporate the solvent
on a steam bath with filtered air from the thin-walled flasks. Decant
the solvent from large flask into tared 500 mL Erlenmeyer flask and
then evaporate. Place the flask in an oven at 70±2°C and dry 2
hours. Hold the extract for further testing, e.g. gas chromatography
and infrared spectroscopy.
- If the extract contains constituents that may volatilize during the
evaporation procedure or is to be used for further analysis, heat the
flask with extract in solution on a 70°C hot plate or a steam plate to
near dryness. Complete evaporation of solvent in vacuum oven at 40°C.
- Remove extracted liner from the thimble* after excess solvent is
removed and place in a tared aluminum weighing dish. Heat to constant
weight at 70°C**. Hold the extracted liner for further testing.
CALCULATIONS
Calculate the percent volatiles as follows:
Volatiles, % = [(A-BJ/A] x 100 , (E-l)
where
A = grams of specimen, as received, and
B = grains of specimen after heating at 105°C.
[Note: Due to potential loss of volatiles when specimens are cut
into cubes, this method of determining volatiles should not be
used as replacement for Matrecon Test Method 1 (Appendix G)]
Calculate the percent extractables as follows:
Extractables, % = (B/A) x 100 , (E-2)
*Note: In cases where the extracted specimen sticks to the extraction
thimble, the extraction thimble should be dried to constant weight
at 70°C before the extraction and the weight recorded as the true
weight of the thimble. After the extraction, the extracted liner
can be dried to a constant weight in the thimble.
**Note: Extracted PVC specimens cannot be dried to a constant weight at 70°C
when they are extracted with a blend of CC14 and CHaOH. It is re-
commended that the sample be dried 72 h at 70°C.
E-4
-------
where
A = grams of specimen after heating at 105°C, and
B = grams of dried extract.
In cases where the extract may contain some constituents which volati-
lized while the extraction solvent was evaporated, the percent extractables
should also be calculated as follows:
Extractables based on loss from specimen, % = [(A-B)/A] x 100 , (E-3)
where
A = grams of specimen after heating at 105°C, and
B = grams of extracted liner.
REPORT
- Identification of the FML.
- In the case of exposed samples, exposure conditions and the length of
exposure.
- Extraction solvent.
- Volatiles.
- Extractables.
- Extractables based on loss from specimen, if calculated.
REFERENCES
ASTM. Annual Book of ASTM Standards. Issued annually in several parts.
American Society for Testing and Materials, Philadelphia, PA:
D297-81. "Methods for Rubber Products—Chemical Analysis," Section
09.01.
D3421-75. "Recommended Practice for Extraction and Analysis of Plas-
ticizer Mixtures from Vinyl Chloride Plastics," Section
08.03.
E-5
-------
-------
APPENDIX F
PROPERTIES OF UNEXPOSED POLYMERIC FMLS
AND OTHER COMMERCIAL SHEETINGS
This appendix presents two data sets resulting from testing a wide range
of unexposed polymeric FMLs and commercial sheetings for physical and ana-
lytical properties. These data sets were developed as part of research
projects to evaluate the effects of exposing FMLs to various hazardous wastes
(Haxo et al, 1985; Haxo et al, 1986) and to study the equilibrium swelling of
FMLs in a range of solvents in order to determine their solubility parameters
(Haxo et al, 1988). These data are presented to provide further information
on specific FMLs discussed in the text, and to present representative data
for different types of FMLs and commercial sheetings.
F-l. Data Set Number 1
These data were developed to establish baseline data for FMLs and
other commercial sheetings exposed in long-term compatibility studies with
various hazardous wastes (Haxo et al, 1985; Haxo et al, 1986). The results
of these studies are presented in Chapter 5. The types of materials tested
included FMLs and sheetings based on:
- Butyl rubber.
- Chlorinated polyethylene (CPE).
- Chlorosulfonated polyethylene (CSPE).
- Elasticized polyolefin (ELPO).
- Ethylene propylene rubber (EPDM).
- High-density polyethylene (HOPE).
- Low-density polyethylene (LDPE).
- Neoprene.
- Polybutylene.
- Polyester elastomer (PEL).
- Polypropylene.
- Polyvinyl chloride (PVC).
These FMLs and sheetings were tested in accordance with the methods listed in
Table F-l. At the time this testing was performed, it was decided that all
F-l
-------
FMLs should be tested in accordance with the same test procedures to minimize
experimental biases and ease interpretation of data. Thus, the tensile
properties of the FMLs, including the fabric-reinforced FMLs, were determined
in accordance with ASTM D412/D638 using a dumbbell-type test specimen and a
jaw separation rate of 20 ipm. The dumbbell-type test specimen was a special
dumbbell which featured, in comparison with the ASTM D412 Die C/ASTM D638
Type IV dumbbell specimen size, smaller tab ends, a shorter narrowed section
and a shorter overall length. The dimensions of this dumbbell are presented
in Figure F-l.
TABLE F-l. TEST METHODS USED TO DETERMINE
PROPERTIES OF POLYMERIC FMLS
Property Test method
Analytical properties
Specific gravity ASTM D297*, Method A/D792
Ash ASTM D297
Volatiles MTM - la
Extractables MTM - 2&
Physical properties
Tensile properties ASTM D412/D638C
Modulus of elasticity ASTM D882 (modified)d
Tear resistance ASTM D624, Die C^
Puncture resistance FTMS 101C, Method 2065f
Hardness ASTM D22409
aMatrecon Test Method 1; see Appendix G.
bMatrecon Test Method 2; see Appendix E.
cMeasured at 20 ipm using a special dumbbell that features,
in comparison with the ASTM D412 Die C/ASTM D638 Type IV dumb-
bell specimen size, smaller tab ends, a shorter narrowed
section, and a shorter overall length. See Figure F-l for
dimensions of the special dumbbell.
Measured using 0.5 x 6-in. strip specimens with an initial
jaw separation of 2.0 in. at the standard initial strain rate
of 0.1 in./in. min. Using a specimen size large enough so that
specimens are tested with an initial separation of 10.0 in.
as specified by ASTM D882 results in somewhat higher values.
eNot measured on fabric-reinforced FMLs.
fU.S. GSA, 1980.
QMeasured on Duro A scale; also measured on Duro D scale if
Duro A reading was greater than 80.
*The references at the end of this chapter the ASTM standards cited in this
appendix and their titles.
F-2
-------
t
1
wo
^
"-V^
^
\
w
f
r* L
i r»
/
^V,^
Figure F-l. Die for special dumbbell. Dimensions are as follows:
W - Width of narrow section 0.25 in.
L - Length of narrow section 1.25 in.
WO - Width overall 0.625 in.
LO - Length overall 3.50 in.
G - Gage length 1.00 in.
D - Distance between grips 2.00 in.
The width of the narrow section of this specimen, W,
is the same as that of the ASTM D412 Die C dumbbell
and the ASTM D638 Type IV dumbbell. It should be noted
that these two dumbbells esentially have the same di-
mensions. The length of the narrow section, L, and the
overall length, LO, of the ASTM D412 Die C/ASTM D638 Type
IV dumbbell are, respectively, 1.30 in. and 4.50 inches.
This special dumbbell was selected so that exposed and unexposed
specimens would be tested in accordance with the same test procedure and so
that the number of specimens that could be died out of the limited-size ex-
posure samples would be maximized. The results of this testing are presented
in Table F-2. Because the stress-strain characteristics of sheetings con-
taining crystalline domains are sensitive to the speed of test, the tensile
and tear properties of the semi crystal line sheetings were also determined at
2 ipm, as is reported in Table F-3. It should be noted that most of these
sheetings were not manufactured for use as FMLs; at the time work was initi-
ated on the project for which this testing was performed, HOPE FMLs were
not commercially available in the United States.
F-2. Data Set Number 2
These data were developed to establish baseline physical and analytical
properties of commercial FMLs used in a study of the equilibrium swelling and
solubility parameters of FMLs (Haxo et al, 1988). This study is described in
Section 5.4.2.3.1. The results of determining the solubility parameters of
the FMLs are presented in Section 4.2.2.4.3. The materials that were tested
included FMLs based on the following polymers:
- Chlorinated polyethylene (CPE).
F-3
-------
TABLE F-2. PROPERTIES OF UNEXPOSED POLYMERIC FMLS*
Polymerb
Compound typed
Fabric, type
Thread count, epi
Nominal thickness, mil
Matrecon FML serial number6
Analytical properties
Specific gravity
Ash (db)f, *
Volatiles, X
Extractables (db)f, %
Solvents
Physical properties
Average thickness, mil
Tensile at fabric break, ppi
Elongation at fabric break, %
Tensile at ultimate break, psi
Tensile at ultimate break, ppi
Elongation at break, %
Set after break, %
Stress at 100% elongation, psi
Stress at 100% elongation, ppi
Stress at 200% elongation, psi
Stress at 200% elongation, ppi
Tear strength (Die C), Ib
Tear strength (Die C), ppi
Puncture resistance:
Thickness, mil
Maximum force-average, Ib
Deformation at puncture, in.
Direction
of test
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Butyl
XL
ezis
44
1.176
4.28
0.46
11.79
HEK
62
• • •
...
...
• • •
1625
1570
104.1
100.2
415
470
18
18
335
280
21.4
17.9
750
615
48.0
39.2
12.88
14.05
201
221
62
39.5
1.17
Butyl
XL
Nylon
22x11
34
57R
1.286
23.46
0.29
6.36
MEK
34
73.1
72.3
25
25
h
h
h
h
60
25
4
2
...
* • *
...
• • •
• • •
...
...
• • *
• • •
...
• • •
34
26.6
0.26
CPE
TP
• • •
• • •
30
77
1.362
12.56
0.14
9.13
n-hept»ne
29
...
...
2055
2340
59.6
66.7
325
480
140
160
1240
560
36.0
16.0
1540
820
44.7
23.4
7.83
6.93
273
239
29
43.9
0.94
CPE
TP
*22
86
1.377
17.37
0.05
6.02
n-heptane
22
...
...
1845
1510
40.6
34.1
355
595
208
235
870
275
19.1
6.2
1210
405
26.6
9.2
4.05
3.91
187
178
22
20.9
0.91
CPE
XL
'36
100
1.390
6.02
0.66
17,42
n-heptane
36
• • •
...
• • •
1880
1935
67.6
69.6
460
400
43
33
555
680
20.0
24.4
1295
1455
46.5
52.3
10.58
10.68
297
304
35
40.0
0.95
CSPE
TP
Nylon
8x8
31
6R
1.343
3.28
0.51
3.77
DMK
31
37.7
34.0
30
15
1845
1610
59.7
52.5
245
240
97
93
995
880
32.2
28.7
1710
1390
55.4
45.3
• • •
...
34
33.7
0.59
Hardness, Durometer points
54A
71A
80A
67A
63A
77A
continued . . .
F-4
-------
TABLE F-2 (CONTINUED)
Polymer1*
Compound typed
Fabric, type
Thread count, epi
Nominal thickness, mil
Matrecon FML serial number6
Analytical properties
Specific gravity
Ash (db)f, %
Volatlles, *
Extractables (db)f, 1
Solvent9
Physical properties
Average thickness, mil
Tensile at fabric break, ppi
Elongation at fabric break, %
Tensile at ultimate break, psi
Tensile at ultimate break, ppi
Elongation at break, %
Set after break, %
Stress at 100% elongation, psi
Stress at 100% elongation, ppi
Stress at 200% elongation, psi
Stress at 200% elongation, ppi
Tear strength (Die C), Ib
Tear strength (Die C), ppi
Puncture resistance:
Thickness, mil
Maximum force-average, Ib
Deformation at puncture, in.
Hardness, Durometer points
Hardness, Durometer points
Direction
of test
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
CSPE
TP
*35
55
1.371
3.32
0.42
4.08
DMK
35
...
• • •
1860
1565
65.0
55.1
260
300
75
97
1110
650
38.9
23.1
1810
1205
63.3
42.5
10.31
9.57
294
271
35
45.0
0.83
78A
320
CSPE
TP
• • •
33
85
1.311
4.02
0.92
8.22
DMK
33
...
...
2345
2055
75.0
66.2
260
325
167
192
1150
750
36.8
24.2
2130
1410
68.2
66.2
9.77
8.78
308
277
33
47.8
0.86
79A
CSPE
TP
Polyester
8x8
30
125R
1.296
3.99
0.12
8.97
DMK
29
53.4
41.4
19
33
...
53.0
46.6
220
245
73
83
...
41.8
29.0
...
51.8
42.5
• • •
• * •
28
30.6
0.61
75A
28D
ELPO
CX
'22
36
0.938
0.90
0.15
5.50
MEK
23
• • *
...
2715
2525
61.0
55.6
675
655
465
445
940
905
21.1
19.9
1035
1000
23.2
22.0
8.90
8.23
388
369
22.5
26.3
0.97
89A
320
EPDM
XL
62! 5
8
1.173
6.78
0.38
23.41
MEK
62
• • •
• • •
1635
1550
98.9
94.9
520
500
14
11
350
320
21.2
19.6
800
740
48.4
45.3
12.7
12.8
206
211
60
56.9
1.46
57A
EPDM
XL
'36
26
1.169
7.67
0.50
.22.96
MEK
36
• • •
• • •
1935
1865
74.5
70.9
440
460
9
9
385
330
14.8
12.5
925
830
35.6
31.5
7.33
7.47
193
197
37
31.3
1.24
58A
EPDM
TP
Polyester
8x8
40
83R
1.199
0.32
0.31
18.16
MEK
39
43.2
29.0
20
1010
870
39.7
34.8
265
240
59
51
890
730
35.0
29.2
990
845
38.9
33.8
• • •
...
39
33.6
0.61
70A
continued . . .
F-5
-------
TABLE F-2 (CONTINUED)
Polymer0
Compound typed
Fabric, type
Thread count, epi
Nominal thickness, mil
Matrecon FHL serial number6
Analytical properties
Specific gravity
Ash (db)f, %
Volatiles, %
Extractables (db)f, %
SolventQ
Physical properties
Average thickness, mil
Tensile at yield, psi
Tensile at yield, ppi
Tensile at break, psi
Tensile at break, ppi
Elongation at break, %
Set after break, %
Stress at 100% elongation,
psi
Stress at 100% elongation,
ppi
Stress at 200% elongation,
psi
Stress at 200% elongation,
ppi
Modulus of elasticity, psi
Tear strength (Die C), Ib
Tear strength (Die C), ppi
Puncture resistance:
Thickness, mil
Maximum force-average, Ib
Deformation at puncture, 1n.
Hardness, Durometer points
Hardness, Durometer points
Direction
of test
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
EPDM
XL
'si
91
1.160
7.33
0.34
23.64
MEK
37
...
...
1865
1790
67.2
66.3
475
500
11
10
375
300
13.5
11.2
915
795
32.9
29.5
• • •
7.27
7.16
196
195
37
29.2
1.17
52A
HOPE
CX
ioo
99
0.943
0.10
0.06
103
2715
2640
306.5
291.9
2185
2195
246.5
231.4
750
675
640
585
1965
1920
221.7
212.3
1980
1945
223.5
215.2
78,600
78,700
...
...
99
131.0
0.33
95A
590
HDPEC
CX
"H
105
0.948
0.03
0.14
0.00
MEK
32
3745
3815
118.4
122.9
2610
2355
81.3
75.8
100
125
85
107
2635
2385
82.2
74.7
...
...
150,150
158,750
40.17
36.00
1215
1110
32
51.2
0.25
90A
600
LDPEC
CX
10
21
0.931
0.00
0.09
3.60
HEK
9
1490
1175
14.2
10.7
2990
2940
28.4
26.8
510
675
395
535
1490
1175
14.2
10.7
1610
1165
15.3
10.6
19,400
24,400
4.07
3.54
420
365
9.6
13.7
0.79
86A
410
LDPEC
CX
'si
108
0.921
0.04
0.18
2.07
MEK
31
1455
1455
41.6
41.8
2085
1975
59.7
56.6
535
575
435
470
1375
1265
39.4
36.2
1385
1300
39.5
37.2
21,960
24,870
14.96
13.91
516
479
31
33.5
0.51
93A
38D
Neoprene
XL
'3!
43
1.477
12.30
0.45
13.69
DMK
33
. • •
...
1910
1660
65.9
56.0
330
310
8
6
490
430
16.9
14.5
1105
970
38.1
32.7
• • •
5.40
5.43
171
170
33
30.6
1.14
57A
• • *
Neoprene
XL
62! 5
82
1.480
13.21
0.19
13.43
DMK
61
...
...
1835
1675
113.8
100.2
390
410
10
9
405
360
25.1
21.5
875
705
54.3
42.2
• • •
11.57
10.70
183
178
60
53.9
1.29
57A
continued . . .
F-6
-------
TABLE F-2 (CONTINUED)
Polymer^
Compound typed
Fabric, type
Thread count, epi
Nominal thickness, mil
Matrecon FML serial number6
Analytical properties
Specific gravity
Ash (db)f, %
Volatiles, %
Extractables (db)f, %
Solvent9
Physical properties
Average thickness, mil
Tensile at yield, psi
Tensile at yield, ppi
Tensile at break, psi
Tensile at break, ppi
Elongation at break, %
Set after break, %
Stress at 100% elongation, psi
Stress at 100% elongation, ppi
Stress at 200% elongation, psi
Stress at 200% elongation, ppi
Modulus of elasticity, psi
Tear strength (Die C), Ib
Tear stength (Die C), ppi
Puncture resistance:
Thickness, mil
Maximum force-average, Ib
Deformation at puncture, in.
Hardness, Durometer points
Hardness, Durometer points
Di rection
of test
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Neoprene
XL
*37
90
1.390
4.67
0.37
21.46
DMK
37
...
...
2185
2010
80.9
74.4
415
415
26
25
565
550
21.0
20.4
1450
1225
53.7
45.3
...
7.74
7.29
207
196
37
44.9
1.01
61A
Polybutylenec
CX
"i
98
0.915
0.08
0.12
4.42
MEK
8
...
...
5625
5580
42.8
44.6
390
375
346
331
2330
2360
17.7
18.9
3035
3200
23.1
25.6
...
2.61
2.85
355
380
7.5
13.9
0.66
94A
Polyester
CX
75
1.236
0.38
0.26
2.74
MEK
7
• • •
• • •
6770
6765
47.4
47.4
560
590
340
370
2715
2455
19.0
17.2
2880
2585
20.2
18.1
...
6.38
5.47
911
782
7.8
29.9
1.30
93A
49D
Polypropylene0
CX
*33
106
0.904
0.04
0.01
0.44
MEK
33
5015
5020
162.5
160.9
i
3035
i
99.5
40
75
16
50
3055
166
...
...
190,900
184,300
12.25
9.37
393
302
33
60.3
0.65
68D
PVC
TP
"3D
11
1.276
6.14
0.15
33.90
CC14 •
30
• • •
...
3005
2750
90.2
82.5
350
365
91
106
1495
1345
44.9
40.4
2140
1885
64.2
56.6
...
11.37
11.04
379
368
31
38.6
0.64
80A
PVC
TP
*20
17
1.254
5.81
0.44
34.11
^ CH3OH
20
...
...
2910
2675
56.7
52.2
350
365
70
83
1360
1180
26.5
23.0
1915
1690
37.3
33.0
...
6.56
5.94
332
301
20
25.30
0.70
76A
290
continued . . .
F-7
-------
TABLE F-2 (CONTINUED)
Polymerb
Compound typed
Fabric, type
Thread count, epi
Nominal thickness, mil
Matrecon FML serial number6
PVC
TP
. ..
...
20
19
Direction
of test
PVC
TP
...
...
30
59
PVC
TP
• • •
• • •
20
88
PVC
TP
• • •
• • •
10
89
PVC
TP
• • •
• • •
20
92
PVC
TP
• • •
• • •
10
93
Analytical properties
Specific gravity
Ash (db)f, X
Volatiles, %
Extractables (db)f, X
Solvent9
Physical properties
Average thickness, mil
1.231
3.65
0.05
38.91
1.280
6.97
0.31
35.86
1.255
2.80
0.17
33.46
eel*
1.308
5.67
0.03
25.17
5.84
0.06
32.75
1.283
4.94
0.12
32.26
22
33
20
11
20
11
Tensile at break, psi
Tensile at break, ppi
Elongation at break, X
Set after break, X
Stress at 100X elongation, psi
Stress at 100X elongation, ppi
Stress at 200X elongation, psi
Stress at 200X elongation, ppi
Tear strength (Die C), Ib
Tear strength (Die C), ppi
Puncture resistance:
Thickness, mil
Maximum force-average, Ib
Deformation at puncture, in.
Hardness, Durometer points
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
2495
2335
52.2
49.0
310
340
55
71
1410
1250
29.5
26.3
1935
1675
40.5
35.1
6.49
6.05
295
275
22
24.0
0.71
72A
2685
2430
87.5
79.2
355
395
45
56
1020
970
33.3
31.6
1715
1445
55.9
47.1
10.25
9.54
313
290
32
40.0
0.75
73A
26D
3395
2910
67.9
58.2
325
335
102
101
1870
1600
37.4
36.0
2610
2190
52.2
43.8
9.26
9.17
463
470
20
28.6
0.56
80A
3715
3085
40.9
33.9
315
325
195
205
1845
1530
20.3
16.8
2715
2195
29.9
24.1
4.49
4.30
408
391
11
17.0
0.48
82A
2435
2145
48.7
42.9
245
255
43
48
1515
1365
30.3
27.3
2170
1885
43.4
37.7
8.70
7.46
435
373
20
27.4
0.62
82A
300
3575
3035
38.1
33.4
325
350
98
117
1750
1420
18.7
15.6
2580
2055
27.5
22.6
4.26
3.99
400
362
11
15.9
0.55
78A
aMethods used for determining properties of the unexposed polymeric FMLs are listed in Table F-l. Note that
all tensile and tear testing reported in this table was done at 20 ipm.
bCPE = chlorinated polyethylene; CSPE - chlorosulfonated polyethylene; ELPO = elasticized polyolefin; EPDM =
ethylene propylene rubber; PVC « polyvinyl chloride.
cUnpigmented, i.e. compounded without a filler.
dXL » crosslinked; TP » thermoplastic; CX * semlcrystalline thermoplastic.
eMatrecon identification number; R • fabric-reinforced.
fdb * Dried basis.
9MEK = methyl ethyl ketone; DMK •= dimethyl ketone • acetone; CC14 + CHyOH = 2:1 blend of carbon tetrachloride
and methyl alcohol.
"Bulk of FMLs1 strength is in the nylon fabric. The butyl coating over the fabric tended not to fail
catastrophically, and no useful value could be obtained for tensile strength at ultimate break.
'Sheeting tended to fail after yielding and no value could be determined for a catastrophic failure.
Source: Haxo et al, 1985, pp 221-25.
F-8
-------
TABLE F-3. PHYSICAL PROPERTIES OF UNEXPOSED SEMICRVSTALLINE POLYMERIC FMLS
AND COMMERCIAL SHEETINGS TESTED AT TWO INCHES PER MINUTE*
Polymerb
Nominal thickness, mil
Matrecon FML serial number
Physical properties
Tensile at yield, psi
Tensile at yield, ppi
Elongation at yield, %
Tensile at break, psi
Tensile at break, ppi
Elongation at break, %
Set after break, %
Stress at 100% elongation,
psi
Stress at 100* elongation,
PPi
Stress at 200% elongation,
psi
Stress at 200% elongation,
ppi
Tear strength (Die C), Ib
Tear strength (Die C), ppi
Direction
of test
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
HOPE
100
99
2385
2460
265
244
15
15
3915
4440
437
441
925
1015
819
900
1660
1720
184
170
1655
1720
184
170
87.2
88.9
839
850
HDPEC
32
105
3695
4020
111
121
17
22
4270
3295
129
98.8
825
860
715
715
2725
2440
82.1
73.2
2725
2460
82.1
73.9
32.4
28.1
992
897
LDPEC
10
21
1205
1015
11.1
9.7
28
18
2845
2645
26.1
25.2
490
635
365
515
1445
1105
13.2
10.5
1610
1125
14.8
10.7
3.9
3.7
424
400
LOPEC
30
108
1270
1255
37.7
36.9
20
18
1690
1645
50.2
48.2
515
535
400
430
1230
1190
36.6
34.9
1185
1145
35.2
33.6
14.2
12.6
462
421
Polypropylene0
33
106
4960
4785
162
159
7
6
5800
4570
190
152
665
640
560
545
3255
2820
106
93.9
3400
3080
111
103
35.3
31.7
1082
987
aTensile properties measured at 2 ipm in accordance with ASTM D638
specimen. See Figure F-l for dimensions of the special dumbbell.
accordance with ASTM D1004 at a test speed of 2 in. per minute.
bHDPE = high-density polyethylene; LDPE « low-density polyethylene.
Compounded without pigment.
Source: Haxo et al, 1985, p 226.
using a special dumbbell test
Tear resistance measured in
F-9
-------
- Chlorosulfonated polyethylene (CSPE).
- Epichlorhydrin rubber (ECO).
- Ethylene proplene rubber (EPDM).
- Neoprene (CR).
- Polybutylene (PB).
- Polyester Elastomer (PEL).
- Polyethylene:
--Low-density (LDPE).
—Linear low-density (LLDPE).
—High-density (HOPE).
—HOPE/ERDM-alloy (HOPE-A).
- Polyurethane (PU).
- Polyvinyl chloride (PVC).
- Elasticized polyvinyl chloride (PVC-E).
- Polyvinyl chloride--oil-resistant (PVC-OR).
Table F-4 presents, by type of sheeting, the methods used in the physical and
analytical testing. Table F-5 presents the solvents used to extract the
sheetings, and Table F-6 presents details on the procedures used in the
tensile and tear resistance testing.
It should be noted that some of this testing was performed in conjunc-
tion with various exposure tests which require the testing of limited size
samples after exposure to a waste test liquid. Thus, the methods cited for
determining tensile properties and modulus elasticity were modified to allow
for the testing of specimens smaller than those required in the respective
methods. These specimen sizes were selected so that exposed and unexposed
specimens could be tested in accordance with the same test procedures and so
that the number of specimens that could be died out of the limited-size
exposure samples could be maximized. Details are presented in Tables F-4 and
F-6. The dimensions of the dumbbell used in testing the cross!inked and
thermoplastic FMLs are presented in Figure F-l.
The results of testing the commerical FMLs are presented in Tables F-7
through F-10.
This appendix also presents information on six laboratory-prepared
compounds, swelling data for which are presented in Section 5.4.2.3.1.
F-10
-------
TABLE F-4. TEST METHODS* USED TO DETERMINE PHYSICAL AND ANALYTICAL PROPERTIES OF POLYMERIC FMLS
Sheeting without fabric reinforcement
Property
Analytical properties
Volatile*
Extractables
Ash
Specific gravity
Physical properties
Thickness (average)
Tensile properties6
Tear resistance6
Modulus of elasticity
Hardness
(Duormeter A or D)
Puncture resistance
Thermoplastic
MTM-lb
MTM-2C
ASTM D297,
Section 34
ASTM D792,
Method A
ASTM D638d
ASTM D638
ASTM D1004
(modified)6
naf
ASTM D2240
FTMS 10 1C,
Method 2065
Crosslinked
MTM-1&
MTM-2C
ASTM D297,
Section 34
ASTM D297,
Method A
ASTM D412<1
ASTM D412
ASTM D624,
Die C
naf
ASTM D2240
FTMS 101C,
Method 2065
Semi crystal line
MTM-lb
MTM-2C
ASTM D297,
Section 34
ASTM D792,
Method A
ASTM D638d
ASTM D638
(modified)6
ASTM D1004
ASTM D882,
Method A
(modified}9
ASTM D2240
FTMS 101C,
Method 2065
Fabric
MTM-lb
MTM-2C
ASTM D297,
ASTM D792,
ASTM D751,
ASTM D751,
ASTM D751,
(8 x 8-in.
na^
ASTM D2240
FTMS 101C,
reinforced
Section 34
Method A
Section 6d
Method B
Tongue Method
test specimen)6
Method 2065
aSee references of this appendix for the sources and titles of the test methods.
bMatrecon Test Method-1. See Appendix G.
cMatrecon Test Method-2. See Appendix E. Solvents used to extract polymeric FMLs are presented in
Table F-5.
^Reported thickness values are the averages of all the values measured on test specimens used in the
physical property testing.
6Details of tensile and tear resistance testing are presented in Table F-6.
fna * Not applicable.
SMeasured using 0.5 x 6-in. strip specimens with an initial jaw separation of 2.0 in. at the standard
strain rate of 0.1 in./in. min. Using a specimen size large enough so that specimens would be tested
with an initial jaw separation of 10.0 in. as specified by ASTM D882-83 would result in higher values.
Source: Haxo et al, 1988, p 113.
F-ll
-------
TABLE F-5. SOLVENTS USED FOR EXTRACTION OF POLYMERIC FMLS
Polymer
Extraction solvent
Chlorinated polyethylene (CPE)
Chlorosulfonated polyethylene (CSPE)
Epichlorohydrin rubber (ECO)
Ethylene propylene rubber (EPDM)
Ethylene vinyl acetate (EVA)
Neoprene (CR)
Polybutylene (PB)
Polyester elastomer (PEL)
Polyethylene:
Low-density (LDPE)
Linear low-density (LLDPE)
High-density (HOPE)
HDPE/EPDM-alloy (HOPE-A)
Polyurethane (PU)
Polyvinyl chloride (PVC)
Polyvinyl chloride—oil-resistant
(PVC-OR)
n-Heptane
Acetone
Methyl ethyl ketone
Methyl ethyl ketone
Ethyl alcohol
Acetone
Methyl ethyl ketone
n-Heptane
Methyl ethyl ketone
Methyl ethyl ketone
Methyl ethyl ketone
Methyl ethyl ketone
n-Heptane
2:1 blend of carbon
tetrachloride and methyl alcohol
Elasticized polyvinyl chloride (PVC-E) Methyl alcohol
2:1 blend of carbon
tetrachloride and methyl alcohol
Source: Haxo et al, 1988, p 114.
F-12
-------
TABLE F-6. DETAILS OF TENSILE AND TEAR RESISTANCE TEST METHODS USED IN TESTING
Test
and test conditions
Sheeting without fabric reinforcement
Cross!inked Thermoplastic Semi crystalline
Sheeting with
fabric reinforcement
Tensile properties
Method
Type of specimen
ASTM D412
"Special"
dumbbell3
Jaw separation rate 20 ipmb
ASTM D638
"Special"
dumbbell9
20 ipmb
ASTM D638
ASTM D638 Type
IV dumbbell
2 ipmb
ASTM D751, Method B
1-in. wide strip and
2-in. jaw separation
12 ipmb
CO
Tear resistance
Method
Type of specimen
Speed of test
ASTM D624
Die C
20 ipmb
ASTM D1004
Die CC
20 ipmb
ASTM D1004
Die Cc
2 ipmb
aSee Figure F-l.
bipm = inches per minute.
CRequired test specimen is the same as Die C from ASTM D624.
^National Sanitation Foundation, 1985, p A-4.
Source: Haxo et al, 1988, p 117.
ASTM D751, Tongue Method
8 x 8-in. test specimen^
12 ipmb
-------
TABLE F-7. ANALYTICAL AND PHYSICAL PROPERTIES OF CHLORINATED POLYETHYLENE,
CHLOROSULFONATED POLYETHYLENE. AND EP1CHLOROHYDRIN RUBBER FMLS
Polymer3
FML numberb
Nominal thickness, mil
Type of compoundc
Thread count, epid
Analytical properties
Specific gravity
Ash-db, %
Volatiles, %
Extractables-db, %
Physical properties
Average thickness, mil
Tensile of fabric at break, ppi
Elongation of fabric at break, %
Tensile at break, psi
Tensile at break, ppi
Elongation at break, %
Stress at 100* elongation, psi
Stress at 100% elongation, ppi
Stress at 200% elongation, psi
Stress at 200% elongation, ppi
Tear strength-tongue, Ib
Tear strength-Die C, ppi
Puncture resistance:
Thickness, mil
Maximum force-average, Ib
Deformation at puncture, in.
Hardness, Durometer points
Hardness, Durometer points
Direction
of test
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
CPE
195
30
TP/AM
na
1.26
0.12
14.85
30.8
• • •
...
1575
1405
48.4
43.2
315
440
1110
585
34.0
18.0
1295
760
39.8
23.3
• • •
268
215
31.0
38.1
0.86
82A
28D
CPE
335R
40
TP/AM
9x9
1.312
15.98
0.40
4.48
39.8
134.3
133.6
31
30
...
39.8
26.3
570
340
• • •
29.7
20.3
• • •
31.2
23.5
:::
...
39.6
50.7
0.31
69A
• * *
CPE
378R
TP/AM
9x9
1.333
• • •
0.25
7.94
35.0
194.4
164.4
29
32
...
51.0
164.0
39
32
• • •
• • •
• • •
:::
83.1^
78.4f
• • •
• • •
79A
CSPE
169R
30
TP/AM
8x8
1.297
2.77
0.39
11.29
27.9
33.0
31.7
25
26
• • •
31.8
30.9
275
285
• • •
23.9
22.4
• * •
30.9
29.3
16.4
28.6
• • •
29.0
27.2
0.67
85A
34D
CSPE
174R
36
TP/AM
10x10
1.364
27.37
0.15
7.15
37.7
190.0
185.0
24
32
...
33.4
30.0
125
155
• • •
32.5
28.1
* • »
• • •
142.0
107.0
• • •
37.6
68.0
0.30
67A
ECO
178
60
XL/AM
na
1.458
4.50
0.55
7.36e
66.9
...
• * *
1050
1120
70.5
76.1
215
200
685
775
46.0
52.6
1035
1120
69.6
76.2
• • *
162
165
67.2
40.0
0.68
64A
«CPE = chlorinated polyethylene; CSPE » chlorosulfonated polyethylene; ECO « epichlorohydrin rubber.
''Serial number assigned by Matrecon to each lot of sheeting received; R » fabric-reinforced sheeting.
CTP = thermoplastic; AM « amorphous; XL » crosslinked.
depi = ends per inch.
eWith methyl ethyl ketone.
fMaximum peak values obtained before delamlnatlon and tearing 1n the opposite direction occurred.
Source: Haxo et al, 1988 p 119.
F-14
-------
TABLE F-8. ANALYTICAL AND PHYSICAL PROPERTIES OF ETHYLENE PROPYLENE RUBBER,
ETHYLENE VINYL ACETATE, NEOPRENE, POLYBUTYLENE, AND POLYESTER ELASTOMER FMLS
Polymer3
FML number^
Nominal thickness, mil
Type of compoundc
Analytical properties
Specific gravity
Ash-db, I
Volatiles, %
Extractables-db, %
Physical properties
Average thickness, mil
Tensile at yield, psi
Elongation at yield, J
Tensile at break, psi
Tensile at break, ppi
Elongation at break, %
Stress at 100% elongation, psi
Stress at 100% elongation, ppi
Stress at 200% elongation, psi
Stress at 200% elongation, ppi
Modulus of elasticity, psi
Tear strength-Die C, ppi
Puncture resistance:
Thickness, mil
Maximum force-average, Ib
Deformation at puncture, in.
Hardness, Durometer points
Hardness, Durometer points
Direction
of test
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
EPDM
232
60
XL/AM
1.166
8.40
0.47
22.78
58.6
• • •
...
1780
1705
103.5
97.8
425
465
445
355
26.0
20.5
965
815
56.2
46.8
• • •
204
214
59.5
49.9
1.05
62A
20D
EVA
308A
20
TP/AM
0.951
0.76
0.05
0.75
20.3
...
...
3655
3500
74.5
71.1
615
770
880
725
18.0
14.7
1025
790
20.9
16.0
• • •
336
363
20.4
50.0
2.08
30A
Neoprene PB PEL PEL
168 221A 316 323
33 30 20 20
XL/AM CX TP/CX/AM TP/CX/AM
1.500
13.65
0.81
11.23
32.0
...
• • •
1990
1800
60.9
54.8
340
325
480
450
14.7
13.6
1110
1020
33.9
31.1
...
148
142
33.4
32.0
0.88
57A
0.907
0.41
0.10
3.68
28.0
1925
1865
20
20
5885
5330
159.9
146.6
405
430
1930
1785
52.4
49.1
3005
2449
81.6
68.5
36,300
36,100
559
547
28.9
55.6
0.72
89A
43D
1.149
0.24
0.18
1.09
20.1
960
950
55
48
6080
5750
122.9
115.0
889
851
920
905
18.6
18.1
955
945
19.3
18.9
• » •
500
523
20.0
41
1.85
37A
1.253
o!24
iO.6
20.4
3330
3180
25
25
8500
8410
175.1
170.0
539
534
2770
2700
14.3
13.7
2860
2880
14.7
14.6
...
972
991
21.2
67
0.97
59A
«EPDM * ethylene propylene rubber; EVA = ethylene vinyl acetate; PB = polybutylene; PEL - polyester
elastomer.
^Serial number assigned by Matrecon to each lot of sheeting received.
CTP = thermoplastic; AM « amorphous; CX * semi crystalline; XL * crossllnked.
Source: Haxo et al, 1988, p 120.
F-15
-------
TABLE F-9. ANALYTICAL AND PHYSICAL PROPERTIES OF LOW-DENSITY POLYETHYLENE. LINEAR
LOW-DENSITY POLYETHYLENE, HIGH-DENSITY POLYETHYLENE, AND HIGH-DENSITY POLYETHYLENE ALLOY FMLS
Polymer3
FML numberb
Nominal thickness, mil
Type of compound0
Analytical properties
Specific gravity
Ash-db, *
Volatiles, %
Extractables-db, %
Physical properties
Average thickness, mil
Tensile at yield, psi
Elongation at yield, %
Tensile at break, psi
Tensile at break, ppi
Elongation at break, %
Stress at 100% elongation, psi
Stress at 100% elongation, ppi
Stress at 200% elongation, psi
Stress at 200% elongation, ppi
Modulus of elasticity, ps1
Tear strength-Die C, ppi
Puncture resistance:
Thickness, mil
Maximum force-average, Ib
Deformation at puncture, in.
Hardness, Durometer points
Hardness, Durometer points
Direction
of test
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
LDPE
309A
20
ex
0.938
o!6?
1.85
22.9
• • •
...
2660
2765
59.3
61.4
470
575
1625
1495
36.2
33.2
1705
1485
38.0
33.0
25,700
29,100
496
442
23.9
28.8
0.71
42D
LLDPE
284
30
ex
0.929
0.07
0.09
0.65
34.4
1505
1540
23
23
5360
5420
185
186
765
800
1505
1470
52.0
50.5
1430
1405
49.4
48.1
49,000
45,800
613
601
34.7
60.2
1.13
91A
47D
HOPE
184
30
CX
0.951
0
0.13
0.73
29.2
3885
4495
20
15
5215
3830
146
107
930
745
2810
2755
78.6
77.1
2830
2830
79.2
79.2
122,000
150,000
892
864
30.1
48.0
0.65
94A
60D
HOPE
263
80
CX
0.953
oils
SO. 60
82.8
3030
2910
20
20
4260
4275
350
359
805
845
2100
1970
173
165
2085
1965
171
165
98,500
91,700
854
846
81.9
109.2
0.55
57D
HOPE
305
30
CX
0.954
0.69
0.22
0.98
27.9
2540
2820
25
25
4110
4390
114
123
760
770
2090
1945
58.2
54.7
2125
1975
59.1
55.5
90,800
764
725
28.0
43.4
0.77
52D
HOPE -A
181
30
CX
0.949
0.32
0.11
2.09
33.5
1975
2070
20
15
3915
3945
130
129
875
910
1635
1640
54.5
53.8
1640
1650
54.6
54.2
59,900
65,100
760
732
33.5
45.5
0.56
90A
51D
aLDPE - low-density polyethylene; LLDPE = linear low-density polyethylene; HOPE
HOPE-A = HDPE/ethylene propylene rubber alloy.
bSer1al number assigned by Matrecon to each lot of sheeting received.
CCX = semicrystalline.
Source: Haxo et al, 1988, p 121.
high-density polyethylene;
F-16
-------
TABLE F-10. ANALYTICAL AND PHYSICAL PROPERTIES OF POLYURETHANE. POLYVINYL
CHLORIDE, ELAST1CIZED POLYVINYL CHLORIDE, AND OIL-RESISTANT POLYVINYL CHLORIDE FHLS
Polymer8
FML number'3
Nominal thickness, mil
Type of compound0
Thread count, epi'd
Analytical properties
Specific gravity
Ash-db, %
Volatiles, X
Extractables-db, %
Physical properties
Average thickness, mil
Tensile at fabric break, ppi
Elongation at fabric break, %
Tensile at break, psi
Tensile at break, ppi
Elongation at break, $
Stress at 100% elongation, psi
Stress at 100% elongation, ppi
Stress at 200% elongation, psi
Stress at 200% elongation, ppi
Tear strength-Die C, ppi
Puncture resistance:
Thickness, mil
Maximum force-average, Ib
Deformation at puncture, in.
Hardness, Durometer points
Hardness, Durometer points
Direction
of test
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Machine
Transverse
Polyurethane
351
TP/AM
na
1.118
oies
1.50
15.0
...
• • •
7775
7040
134
122
500
525
1020
955
17.6
16.5
1305
1145
22.5
19.8
420
446
15.0
72.2
2.00
86A
33D
PVC
153
30
TP/AM
na
1.263
5.31
0.38
34.57
29.4
...
...
2860
2540
94.3
83.9
315
335
1495
1315
49.2
43.5
2120
1835
70.0
60.6
346
343
33.3
44.3
0.69
73A
28D
PVC-E
176R
30
TP/AM
20x20
1.219
5.12
0.44
9.13
36.1
342
349
24
22
• • •
342
349
24
22
• • •
• • •
...
• • •
...
36.3
101.5
0.32
93A
42D
PVC -OR
144
30
TP/AM
na
1.356
10.82
0.21
30.97
32.8
• • •
• • •
2655
2275
86.0
74.9
365
355
1235
1085
40.1
35.7
1800
1560
58.3
51.3
323
277
33.0
33.9
0.66
72A
24D
polyvinyl chloride: PVC-E « elasticized polyvinyl chloride; PVC-OR • oil-resistant
polyvinyl chloride.
bSerial number assigned by Matrecon to each lot of sheeting received; R = fabric-reinforced
sheeting.
CTP - thermoplastic; AM » amorphous.
dna « Not applicable.
Source: Haxo et al, 1988, p 122.
F-17
-------
The composition of the these compounds and information on their molding
conditions and their extractables content are presented in Tables F-ll and
F-12. These compounds include four CSPE compositions, a nitrile rubber
composition, and a PVC composition plasticized with di(ethylhexyl) phthalate.
Among the four CSPE compositions are three gum compounds that contain no
filler but vary in the level of crosslinking. The fourth CSPE composition
contains 100 parts of carbon black similar to that used in CSPE liner
compounds.
REFERENCES
ASTM. Annual Book of ASTM Standards. Issued annually in several parts.
American Society for Testing and Materials, Philadelphia, PA:
D297-81. "Methods for Rubber Products—Chemical Analysis," Section
09.01.
D412-83. "Test Methods for Rubber Properties in Tension," Sections
08.01, 09.01, and 09.02.
D624-86. "Test Method for Rubber Property—Tear Resistance," Section
09.01.
D638-84. "Test Method for Tensile Properties of Plastics," Section
08.01.
D751-79. "Methods of Testing Coated Fabrics," Section 09.02.
0792-66(1979). "Test Methods for Specific Gravity and Density of
Plastics by Displacement," Section 08.01.
D882-83. "Test Method for Tensile Properties of Thin Plastic Sheet-
ing," Section 08.01.
01004-66(1981). "Test Method for Initial Tear Resistance of Plastic
Film and Sheeting," Section 08.01.
D2240-86. "Test Method for Rubber Property—Durometer Hardness,"
Sections 08.02 and 09.01.
Haxo, H. E., R. S. Haxo, N. A. Nelson, P. D. Haxo, R. M. White, and S.
Dakessian. 1985. Liner Materials Exposed to Hazardous and Toxic
Wastes. EPA-600/2-84/169 (NTIS No. PB 85-121 333). U.S. Environmental
Protection Agency, Cincinnati, OH. 256 pp.
Haxo, H. E., R. S. Haxo, N. A. Nelson, P. D. Haxo, R. M. White, and S.
Dakessian. 1986. Liner Materials Exposed to Toxic and Hazardous
Wastes. Waste Management and Research 4:247-264.
F-18
-------
TABLE F-ll. COMPOSITION OF LABORATORY-PREPARED COMPOUNDS
OF CSPE, NITRILE RUBBER, AND POLYVINYL CHLORIDES
CSPE
Ingredient DOY-3b DOZ-2b DPOb DPPb
CSPE (Hypalon 45) 100 100 100 100
Nitrile rubber
(Hycar 1052-30) ... ...
PVC (Geon 135) ... ...
Di (ethyl hexyl ) phthalate
Nit rile
rubber PVC
DPNb DPQb
• • • • • •
100
100
50
MT black ... 100
MgO (Maglite D) 4 4 10 4
Peroxide (Varox powder) ... ... 6 1.5
HVA-2C ? OR
I I V n C_ *•• ••• f- \J m *J ••• •••
Lead stearate ... ... ... ... ... 2.0
Stearic acid (F300)
ZnO (Protox 168)
TMTDSd (Tuex)
Carbowax 4000
Pentaerythritol
Tetrone Ae
Total
• • •
• • •
• • •
1.5
3.0
2.0
110.5
• •• ••• ••• -L • U
••• ••• ••• D • U
••• ••• ••• 0 • D
1*0 • • • ••• •••
••• ••• ••• •••
••• ••• ••• ••*
205.5 118.0 106.0 109.5
0.2
• • •
• • •
• • •
• • •
• • •
152.2
aFormulation in parts by weight.
bMatrecon identification code.
cHVA-2 = N,N-m-pheny1enedimaleimide (DuPont), a curing adjuvant for CSPE.
^TMTDS = tetramethyl thiuram disulfide.
eTetrone A = dipentamethylene thiuram hexasulfide, accelerator or sulfur
source.
Source: Haxo et al, 1988, p 115.
F-19
-------
TABLE F-12. MOLDING CONDITIONS AND EXTRACTABLES
OF THE LABORATORY-PREPARED COMPOUNDS
Item
Molding conditions'5
Temperature, °C
Time, min.
Extractablese, %
DOY-33
160
25
5.9
CSPE
DOZ-2*
160
60
<1.0
DPOa
150
20
6.8
DPpa
140
40C
1.9
Nit rile
rubber
DPNa
150
40
1.0
PVC
DPQa
150
d
34.3
aMatrecon identification number.
bMolded in small slabs of 25 to 30-mil thickness.
cCooled in the press.
dCooled immediately after filled mold was placed in a press.
eExtractables of the composition were calculated based upon their
respective formulations. The polymer component was assumed to be
nonextractable.
Source: Haxo et al, 1988, p 116.
F-20
-------
Haxo, H. E., T. P. Lahey, and M. L. Rosenberg. 1988. Factors in Assessing
the Compatibility of FMLs and Waste Liquids. EPA/600/2-88/017 (NTIS No.
PB 88-173-372/AS). U.S. Environmental Protection Agency, Cincinnati,
OH. 143 pp.
National Sanitation Foundation (NSF). 1985. Standard Number 54: Flexible
Membrane Liners. Rev. Standard. National Sanitation Foundation, Ann
Arbor, MI.
U.S. General Services Administration. 1980. Method 2065: Puncture Resis-
tance and Elongation Test (1/8-Inch Probe Method). In: Federal Test
Method Standard 101C. U.S. General Services Administration, Washington,
D.C.
F-21
-------
-------
APPENDIX G
PROCEDURE FOR DETERMINATION OF THE VOLATILES OF EXPOSED
AND UNEXPOSED FMLS [MATRECON TEST METHOD 1 (MTM-1) - AUGUST 1982]
Editorially Revised November 1987
SCOPE
This test can be performed on unexposed polymeric FMLs and on FML
samples that have been exposed to a leachate or other liquid.
SIGNIFICANCE
This test can be used to determine the volatiles of an unexposed FML or
the volatile fraction absorbed by an exposed FML, including water, volatile
oils, and solvents. Moisture is removed by heating specimens in individual
desiccators at 50°C. Organic volatiles are then removed by heating specimens
for 2 hours at 105°C in an air-circulating oven. The composition of the
organic volatiles can be determined by headspace gas chromatographic analysis
of vapors sampled from a sealed can in which a specimen has been heated.
Nonvolatile dissolved or absorbed components of a specimen can be determined
by the extractables test which is run after the volatiles have been removed
(see Appendix E, Matrecon Test Method 2). The volatiles should be determined
as soon as possible after exposed samples have been removed from exposure and
measured for weight and dimensional changes, or, for unexposed samples, as
soon as possible after they have been received by the testing facility. By
identifying the orientation of the disk with respect to the sheeting at the
time it was died out, the grain of the sheeting can be established.
DEFINITIONS
Volatiles are the fraction of weight lost by a specimen during the
specified heating process described below.
APPARATUS
- Two-inch interior diameter circular die.
- Analytical balance.
- Ai r oven.
- Individual desiccators with CaCl2.
G-l
-------
TEST SPECIMEN
Two-inch diameter disks died out of an FML sample.
NUMBER OF TEST SPECIMENS
All determinations should be run in duplicate.
PROCEDURE
1. Draw a line on the sheeting to mark "grain" or machine direction.
If the "grain" is unknown, draw a random straight line on the
sheeting.
2. Die out a 2-in. diameter disk so that the line falls approximately
in the middle of the specimen.
3. Weigh specimen in tared, closed container to the nearest 0.0001 g.
Record weight as the "as-received weight."
4. Place each specimen in an individual desiccator with CaCl2 as the
desiccant. Place the desiccator in a 50°C oven for four days.
5. Remove desiccator from oven and cool for 20 minutes at room temper-
ature. Weigh specimen to 0.0001 g. Record weight as the "desic-
cated weight."
6. Dry specimen on Teflon screen for 2 hours in a circulating air oven
heated to 105±2°C.
7. Cool specimen in desiccator for 20 minutes and weigh on analytical
balance to 0.0001 g; record weight as the "oven-dried weight."
8. Measure diameter in machine and transverse directions. Record to
0.001 inches.
9. If machine direction is unknown, find and record largest and small-
est diameter of disk. Mark small diameter as the machine direction
on disk as shown in Figure G-l. Use the dried disk to determine the
orientation of the sheeting from which it was died out.
10. Retain specimens for additional testing, e.g. specific gravity,
thermogravimetry, extractables, GC, IR, ash content, etc.
Note 1: For cases in which the grain direction of the FML sample is
known, Steps 1, 8, and 9 can be eliminated.
Note 2: For cases in which an unexposed FML sample is being tested, the
"as-received weight" can be determined directly (Step 3). In
addition, Steps 4 and 5 can also be eliminated.
G-2
-------
Note 3: If the specific gravity of a highly swollen, exposed FML sample
is to be determined, the volatiles may need to be removed from
the test specimens more gradually than they are in the above
test procedure to prevent blisters from forming. Specimens can
be allowed to dehydrate for 1 week in moving air before being
placed in an oven heated to 50°C, or they can be allowed to come
to constant weight at 50°C before being placed in and oven
heated to 105°±2°C.
As received After air oven heating
Figure G-l. Machine direction determination.
CALCULATIONS
Calculate the percent volatiles as follows:
Volatiles after desiccation, % = [(A - B)/A] x 100 ,
and
where
(G-l)
(G-2)
(G-3)
Volatiles after 105°C heating, % = [(B - C)/A] x 100 ,
Total volatiles, % = [(A - C)/A] x 100 ,
A = grams of specimen, "as-received weight,"
B = grams of specimen, "desiccated weight," and
C = grams of specimen, "oven-dried weight."
REPORT
- Identification of the FML.
- In the case of exposed FMLs, the exposure conditions and the length
of exposure.
- Results of volatiles calculations.
G-3
-------
-------
APPENDIX H
TUB TEST OF POLYMERIC FMLS
Editorially Revised November 1987
SIGNIFICANCE
The tub test exposes polymeric FMLs under conditions that simulate some
of the conditions that exist in a lined surface impoundment in which a liner
is in contact with a waste liquid and is not covered with soil. The effects
of exposure to sun, temperature changes, ozone, and other weather factors
can be assessed simultaneously with the effect of a given waste on a specific
FML. The level of the waste is allowed to fluctuate so that an area of the
liner is subjected to the effects of both the waste and weather intermit-
tently. This alternating of conditions, which is especially harsh on FMLs
and other liner materials, is encountered in the field.
SUMMARY OF METHOD
A small tub, lined with a polymeric FML is partially filled with a
waste liquid and exposed to the weather for an unspecified length of time.
The condition of the FML is monitored during exposure. At the end of ex-
posure, the condition of the FML is assessed. The physical and analytical
properties of selected areas of the liner are determined.
APPLICABLE DOCUMENTS
- ASTM D297, "Methods for Rubber Products - Chemical Analysis."
- ASTM D412, "Test Methods for Rubber Properties in Tension."
- ASTM D624, "Test Method for Rubber Property - Tear Resistance."
- ASTM D638, "Test Method for Tensile Properties of Plastics."
- ASTM D751, "Standard Methods of Testing Coated Fabrics."
- ASTM D882, "Test Methods for Tensile Properties of Thin Plastic
Sheeting."
- ASTM D1004, "Test Method for Initial Tear Resistance of Plastic Film
and Sheeting."
H-l
-------
- ASTM D2240, "Test Method for Rubber Property - Durometer Hardness."
- ASTM D3421, "Recommended Practice for Extraction and Analysis of
Plasticizer Mixtures from Vinyl Chloride Plastics."
- FTMS 101C, Method 2065, "Puncture Resistance and Elongation Test
(1/8-inch Radius Probe Method)."
- Matrecon Test Method 1, "Procedure for Determination of the
Volatiles of Exposed and Unexposed Polymeric FMLs" (see Appendix
G).
- Matrecon Test Method 2, "Procedure for Determination of the
Extractables Content of Exposed and Unexposed Polymeric FMLs" (see
Appendix E).
EQUIPMENT AND SUPPLIES
- Plywood tub. The suggested tub design is as follows: The tub should
be constructed of 0.75-in. exterior grade plywood with sides sloping
outward at a 1 horizontal :2 vertical slope. The inside base should
measure 7 x 12 in., and the opening at the top should measure 19.75 x
24.5 inches. A sketch of this design is presented in Figure H-l.
- Chicken-wire cover to fit over tub to prevent birds from bathing in
the wastes (Figure H-2).
- Lined catch basin fitted with a drain designed to prevent waste
overflow or leaks from contacting the roof top (Figure H-2). The
suggested catch basin dimensions are 8 ft x 6 ft x 4 inches.
- Corrugated plastic cover to fit over tub during rainy weather. The
cover should be capable of being secured to the catch basin.
- Label for the liner specimen.
- Stress-strain machine suitable for measuring tensile strength, tear
resistance, and puncture resistance in accordance with the appropri-
ate methods.
- Jig for testing puncture resistance in accordance with FTMS 101C,
Method 2065.
- Air-circulating oven.
- Dial or digital micrometer.
- Analytical balance.
- Two-inch interior-diameter circular die.
H-2
-------
TOP VIEW
7"
12"
19.75"
ISOMETRIC DRAWING OF TUB
(Sketch not to scale)
24.5'
24.5'
10"
60'
B"
(varies)
8.75"
FRONT VIEW
SIDE VIEW
Figure H-l. Tub used in the outdoor exposure of polymeric FMLs in
contact with wastes. The tub is lined with an FML and
filled from 3/4 to 7/8 full with a waste liquid. The
liquid level is allowed to fluctuate (Source: Haxo et al,
1985, p 157).
Dies for cutting tensile and tear specimens as required.
Individual desiccators with calcium chloride (CaCl2)»
Soxhlet extractor (ASTM D3421) or rubber extraction apparatus
(ASTM D297) and associated extraction apparatus including extraction
thimbles and flasks (see Matrecon Test Method 2, presented in Appendix
E).
Meter stick or similar device to measure waste depth.
Thermometers.
H-3
-------
pH meter.
Conductivity meter.
Figure H-2.
The open exposure tubs lined with polymeric FMLs and partially
filled with waste liquids. They are covered with chicken-wire
and placed in a lined shallow basin. During rainy weather these
cells are protected by a corrugated plastic cover. (Source:
Haxo et al, 1985, p 158).
TEST SPECIMEN
Piece of FML, large enough to fold over edges of the tub; approximate
size 4 ft x 4 feet. A seam should be incorporated into the center of the
FML sample in accordance with the supplier's instructions. Fabricate the
seam so that there is sufficient free overlap to perform peel testing. For
materials that need proprietary equipment for seaming, a sample supplied by a
fabricator with a field seam already incorporated in it is acceptable.
Sufficient FML should be retained to perform baseline testing of both the
sheeting and the seam.
PROCEDURE
- Obtain a representative
classifies or separates.
sample of the waste liquid.
Determine the pH, electrical
Note if waste
conductivity,
H-4
-------
and total solids of the waste sample. A more extensive waste analysis
may also be required.
Perform the following tests on an unexposed sample of the polymeric
FML from the same roll as the sheeting used in fabricating the tub
liner:
—Volatiles, Matrecon Test Method 1 (Appendix G).
--Extractables with suitable solvent, Matrecon Test Method 2
(Appendix E).
--Tear resistance, machine and transverse directions, five
specimens each direction. See Table H-l for appropriate test
method and recommended speed of test.
--Puncture resistance, five specimens, FTMS 101C, Method 2065.
—Tensile properties, machine and transverse directions, five
specimens each direction. See Table H-l for appropriate test
method, recommended test specimen, speed of test, and values
to be reported. The dumbbell recommended for testing unrein-
forced FMLs is presented in Figure H-3.
—Modulus of elasticity, machine and transverse directions,
5 specimens each direction, ASTM D882 (modified), semicrystal-
line FMLs only, using 0.5 x 8-in. strip specimens with a
4.0-in. gage length extended at the standard initial strain
rate of 0.1 in/in, min. (Note: Testing specimens with a
10.0-in. gage length as specified by ASTM D882 results in
higher values.)
—Hardness, Duro A (Duro D if Duro A reading is greater than 80),
ASTM D2240.
--Seam strength in shear mode, 5 specimens, ASTM D882, with
1-in. wide strips at a jaw separation rate of 2 ipm. ASTM D638
Type I specimens may be substituted for the 1-in. wide strip
specimens if it is necessary to concentrate stress on the seam
area. Report the locus of break for the tested specimens.
—Seam strength in peel mode, 5 specimens, ASTM D413, in 90° peel
with 1-in. wide strips at a jaw separation rate of 2 ipm. ASTM
D638 Type I specimens may be substituted for the 1-in. wide
strip specimens if it is necessary to concentrate stress on the
seam area. Report the locus of break for the tested specimens.
Drape the FML specimen over a tub and fold it so that the specimen
fits the inside contours and edges of the tub. Allow the excess
sheeting to hang freely over the edges of the tub. Attach an
identification tag to one corner of the tub liner.
H-5
-------
TABLE H-l. RECOMMENDATIONS FOR TENSILE AND TEAR TESTING FOR TUB TEST
Test
Tensfle properties
Method
Type of specimen
CrossI inked
ASTM D412
Special dumbbell8
FML without fabric reinforcement
Thermoplastic
ASTM D638
Special dumbbell*
Semi crystal line
ASTM 0638
Special dumbbell8
Fabric-reinforced
ASTM 0751, Method B
1-in. wide strip and 2-in. jaw
Speed of test
Values to be reported
20 ipm
Tensile strength, psi
Elongation at break, X
Tensile set after break, %
Stress at 100, 200, and 300*
elongation, psi
20 ipm
Tensile strength, psi
Elongation at break, %
Tensile set after break, I
Stress at 100, 200, and 300%
elongation, psi
2 ipm
Tensile stress at yield, psi
Elongation at yield, I
Tensile strength at break, psi
Elongation at break, %
Tensile set after break, %
Stress at 100, 200, and 300»
elongation, psi
separation
12 ipm
Tensile at fabric break, ppi
Elongation at fabric break, T
Tensile at ultimate hreak, ppi
Elongation at ultimate break, »
Tensile set after break, %
Stress at 100, 200, and 300%
elongation, ppi
Tear resistance
Method
Type of specimen
Speed of test
ASTM D624
Die C
20 ipm
ASTM D1004
Die Cc
20 ipm
ASTM 01004
Die Cc
2 ipm
b
...
...
»See Figure H-3.
^o tear resistance test is recommended for fabric-reinforced FMLs in the tub test because of sample-size constraints.
cTest specimen required In ASTM D1004 1s the same as Die C from ASTM D624.
-------
t
1
wo
1
\
"""v^
^
\
w
T
,_. _ in
x^
\
Figure H-3. Die for special dumbbell. Dimensions are as follows:
W - Width of narrow section 0.25 in.
L - Length of narrow section 1.25 in.
WO - Width overall 0.625 in.
LO - Length overall 3.50 in.
G - Gage length 1.00 in.
D - Distance between grips 2.00 in.
The width of the narrow section of this specimen, W,
is the same as that of the ASTM D412 Die C dumbbell
and the ASTM D638 Type IV dumbbell. It should be noted
that these two dumbbells essentially have the same dimen-
sions. The length of the narrow section, L, and the
overall length, LO, of the ASTM D41'2 Die C/ASTM D638 Type
IV dumbbell are, respectively, 1.30 in. and 4.50 inches.
Place the lined tub in the catch basin so that it is oriented in a
specific direction. It is recommended that the length of the seam
runs in a north-south direction so that part of the seam can be
exposed to as much sunlight as possible. Fill the tub 3/4 to 7/8 full
with the waste liquid. Approximately 4.5 gal of waste is required to
fill the suggested tub design to the recommended height. Cover the
tub with chicken-wire to prevent birds from bathing in the waste.
During exposure, monitor the ambient temperature and the level and
temperature of the waste at regular intervals. At the same time,
inspect the tubs for cracking, opening of seams, and other forms of
FML deterioration. Cover the tubs during rainy periods to prevent
waste overflow. Add water to the tub when the waste level drops below
4 inches. In the case of an oily waste, water that has accumulated
from dew may need to be pumped from the bottom of the tub. Liquid
removed from the tub should be analyzed for pH, electrical conduc-
tivity, percent solids, and other parameters as appropriate. During
rainy periods, water in the catch basin should be monitored for pH and
conductivity to indicate whether there is leakage from a tub contain-
ing a highly acidic or a highly alkaline waste.
H-7
-------
The tub exposure should be discontinued at the end of a predetermined
exposure period or if the liner shows significant signs of deteriora-
tion. Exposure for several years is recommended. The following
procedure should be used in dismantling the tub:
—Examine the tub liner and the waste. Record observations
regarding the waste appearance and, if it has stratified,
the depth of the layers. Record observations on the condi-
tion of the tub liner. In particular, check for effects of
weathering at the upper edge of the tub and places where the
liner has been folded. Photograph the tub.
—Scoop out the waste. If the waste has stratified, take care
to remove each layer separately so as not to disturb the
layer(s) below. Save the waste for analyses.
--Record observations on the areas of the liner that were
exposed to the waste. Note swelling, discoloration, deposits,
condition of the seams. Note any sludge still remaining on
the liner. Determine the area of the liner that was exposed
intermittently to the weather and the waste. Using a wax
pencil, indicate this area on the liner.
--Detach the liner from the plywood tub and record any observa-
tions regarding the back of the liner. Note any moisture,
discoloration, and the condition of the seam. Scoop any
remaining sludge off the liner. Using a wax pencil, indicate
the directional orientation of the tub liner, i.e. the north,
south, east, and west sides of the liner. Also mark the top
edge of the tub and waste-phase depths on the liner.
—Lay the liner flat and photograph it. Make a drawing of the
liner. Indicate on the drawing the tub edge, waste-phase
levels, bottom area, folds, any signs of FML deterioration
such as cracks, etc.
—Clean off the liner. Seal the liner in a polyethylene bag to
prevent loss of volatiles.
Cut a 1-in. wide strip across the width of the liner parallel to
the seam so that the strip runs from one edge of the liner along an
area of the liner that was exposed on the bottom of the tub to the
other edge. Measure the thickness of the strip using a dial or
digital gage every 0.5 inches. Graph the results.
Based on the condition of the liner, determine the areas for
testing. Suggested areas for testing include:
--North side (side facing south), exposed only to weather
(including the sun).
H-8
-------
--North side (side facing south), exposed intermittently to the
waste and the weather (including the sun).
—Bottom, exposed only to the waste.
--South side (side facing north), exposed intermittently to the
waste and the weather (not including the sun).
—South side (side facing north), exposed only to the weather (not
including the sun).
Perform the following tests on the selected areas of the exposed FML
as soon as possible after the liner has been removed from exposure:
--Volatiles, Matrecon Test Method 1 (Appendix G).
--Extractables, with the same solvent used to determine the
extractables of the unexposed sample, Matrecon Test Method 2
(Appendix E).
—Tear resistance, machine and transverse directions, a minimum
of two specimens each direction per tested area. See Table
H-l for appropriate test method and recommended speed of
test.
—Puncture resistance, a minimun of two specimens per tested
area, FTMS 101C, Method 2065.
—Tensile properties, machine and transverse directions, a
minimum of two specimens each direction per tested area.
See Table H-l for appropriate test method, recommended test
specimen, speed of test, and values to be reported. The dubbell
recommended for testing unreinforced FMLs is presented in
Figure H-3.
—Hardness, Duro A (Duro D if Duro A reading is greater than
80), ASTM D2240.
—Modulus of elasticity, machine and transverse directions, a
minimum of two specimens each direction per tested area, ASTM
D882 (modified), semi crystal line FMLs only, using 0.5 x 8-in.
strip specimens with a 4.0-in. gage length extended at the
standard initial strain rate of 0.1 in./in. minute.
—Seam strength in shear mode, a minimum of two specimens, ASTM
D882, at a jaw separation rate of 2 ipm with the same type of
specimen used to test the unexposed seam sample. Report
locus of break for the tested specimens.
—Seam strength in peel mode, a minimum of two specimens, ASTM
D413, in 90° peel at a jaw separation rate of 2 ipm with the
same type of specimen used to test the unexposed seam sample.
H-9
-------
Note: Test specimens cut from the seam of the exposed
liner should be alternated between peel and shear
test specimens.
A drawing of an exposed liner including the layout pattern for sam-
pling the liner is presented in Figure H-4.
- Analyze the waste using the appropriate parameters.
NORTH
1 - in. strip used
with roller gage
EAST
EXPLANATION
S Visible cracks
Area swollen
and wrinkled
Smooth area
under waste
Tear die C
Tensile
dumbell
O Volatiles
Cl Punctures
SOUTH
Figure H-4. Drawing of an exposed liner showing locations where the test
specimens were cut and the directional orientation in which the
liner was exposed. Location of strip for measuring thickness
across specimens is also shown. Note that this FML sample
did not include a seam. (Source: Haxo et al, 1985, p 163).
REPORT
- Summarize the results of monitoring the tub. Include observations
on the appearance of the tub liner and the waste at the end of
the exposure period.
H-10
-------
- Summarize the results of testing the tub liner as follows:
--Report test values for volatiles of the unexposed FML and the
tested exposure areas.
--Report test values for extractables of the unexposed FML and
the tested exposed areas. Report the solvent used to perform
the extractions.
--Report test values for tear resistance and tensile properties
of the unexposed FML and percent retention of the unexposed
properties for each of the tested exposed areas.
—Report test values for puncture resistance of the unexposed
FML and the tested exposed areas.
--Report test values for hardness of the unexposed FML and the
change in points from the test values obtained on the unexposed
FML for each of the tested exposed areas.
--Report test values for the seam strength in peel and shear
modes of the unexposed sample and for each of the tested
exposed areas. Include a description of the seam system and a
description of the manner in which the test specimens broke.
--Present a drawing of the exposed liner indicating the exposed
areas, any signs of FML deterioration, and the pattern used
for cutting test specimens from the liner.
--Present the thickness profile of the 1-in. wide strip cut
from the liner.
—Report the procedures used in performing the testing.
- Summarize the results of testing the waste liquid.
REFERENCE
Haxo, H. E., R. S. Haxo, N. A. Nelson, P. D. Haxo, R. M. White, and S.
Dakessian. 1985. Liner Materials Exposed to Hazardous and Toxic
Wastes. EPA/600/2-84/169 (NTIS No. PB-85-121333). Cincinnati, OH:
U.S. Environmental Protection Agency. 256 pp.
H-ll
-------
-------
APPENDIX I
DESIGN OF THE PIPE NETWORK FOR
LEACHATE COLLECTION SYSTEMS
A primary or secondary leachate collection system in a double liner
system for the containment of hazardous wastes typically consists of:
- A drainage layer.
- A filter layer.
- A strategically-placed network of perforated pipe for transporting
leachate or waste liquid from the drainage layer to the sump/manhole
system from which the liquid is withdrawn.
- A bedding layer for the pipe network.
- A sump/manhole system which allows collection of the leachate or
waste liquid and access to the pipe network for inspection and pos-
sible repairs throughout the monitoring periods.
- Mechanical and electrical equipment for conveying the leachate from
the collection system to a separate storage or treatment area and
for monitoring and controlling the level of leachate above the liner.
The pipe can be installed either in a trench condition or in a condition, in
which the pipe projects above the liner. The function of the primary leach-
ate collection system at landfills and waste piles is to minimize the head
of leachate on the top liner during operation of the unit and during the
post-closure care period. The collection and removal system is required by
present EPA regulations to be capable of maintaining a leachate head of less
than 1 ft. The function of the secondary leachate collection system between
the two liners is to detect and collect liquids that have leaked through the
top liner and remove them for treatment and/or disposal.
This appendix discusses the flow capacity, sizing, structural stability,
and deflection of pipe used in a pipe network for leachate collection systems
with particular emphasis on primary leachate collection systems. A series
of charts and tables is presented for use in the design and analysis of pipe
networks. Various types of pipes are discussed in Section 4.2.7.
1-1
-------
I.I FLOW CAPACITY
As indicated in Chapter 7, the spacing of the collection pipes in a
collection system above the top liner influences the maximum head of leachate
on the base of a landfill or waste pile, given a uniform rate of leachate
percolation through a saturated fill and the permeability of the medium
through which the leachate is withdrawn. Figure 1-1 can be used to select
the required pipe spacing given an allowable leachate head (<1 ft) over the
base of the unit. Figure 1-2 shows the flow that must be carried in a
collection pipe for various percolation rates and collection pipe spacings.
With the required flow known, Figure 1-3 can be used to select pipe sizes.
Designs incorporating 6-in. diameter perforated pipes spaced 50 to 200 ft
apart will effectively minimize head on the liner in most cases (EPA, 1985).
1.2 STRUCTURAL STABILITY OF PIPE
1.2.1 Introduction
Pipes installed at the bottom of a containment unit for collecting
leachate and conveying it to withdrawal wells can be subjected to high
loading of waste fills, which can rise several hundred feet above the pipe.
Leachate collection pipes beneath containment units generally are
installed in one of two conditions (1) a trench condition or (2) a positive
projecting condition. These installation conditions are shown in Figure 1-4.
In analyzing the structural stability of pipe under an imposed loading, the
pipe is considered either a rigid or flexible conduit. Examples of rigid
conduits are concrete and cast iron pipe. Polymeric and fiberglass pipes
are examples of flexible pipe. Because a landfill environment can be highly
corrosive, polymeric pipe materials are generally selected for use in leach-
ate control systems due to their relatively inert properties. This section
of this appendix discusses the structural stability of flexible pipe in
landfill applications.
1.2.2 Loads Acting on Pipe
Loads are determined for one of two conditions: a trench condition or a
positive projecting condition.
1.2.2.1 Trench Condition (Figure 1-4)--
This condition is assumed to exist whenever the top of the pipe is
located below the ground surface. Load on the pipe is caused by both the
waste fill and the trench backfill. These two components of the total
vertical pressure on the pipe are computed separately and then added to
obtain the total vertical pressure acting on the top of the pipe. The waste
fill is assumed to develop a uniform surcharge pressure, qf, at the base of
the unit. The magnitude of qf is given by the expression:
qf =
1-2
-------
Drainage
Layer.
Aliiii
Uniform Infiltration Rate (q)
-2t>
\
Compacted'
Clay
FML
-Leachate
Collection
Pipe
For leachate flow conditions represented
in Figure a, the following equation ap-
proximates the flow net solution:
where,
(a) Cross Section of Liquid Surface
0.01
0.1
10
q = uniform infiltration rate
K = coefficient of permeability
(i.e. of drainage layer above
liner)
h = head of leachate above
liner
b = width of area contributing
to leachate collection pipe.
Example for a 1-ft thickness of perme-
able material overlying FML liner:
q = 2 in./month = .00548 ft/d
K (sand) = 2 x 10'2 cm/sec = 50 ft/d
b = 100 ft and q/K = 1 x 1(H
from chart,
b/h = 100
therefore, the head (h) acting on the
liner = 1 ft.
Figure 1-1. Determination of leachate head on FML liners using flow net solution
(Cedergren, 1967). Figure (b) is a log-log plot with subdivisions shown
on the right and top of graph. Methods of estimating leachate production
rate, i.e. uniform infiltration rate, are discussed in Section 7.3.1.1.7.
1 x 10'
1 xlO
5 10 20 50 100 200 500 1000
b/h
(b) q/K vs. b/h for Drainage Material
-------
.0
§
-------
I
en
so
0 2
0.3 0.4 0.5 0.6 0.7 0.80 9 1 .0
20 3.0 40 50 6.0 7.08.09.0 10
Slope of pipe in feet per thousand feet
Figure 1-3. Sizing of leachate collection pipe (Plastic Pipe Institute, 1975). It
should be noted that the EPA draft Minimum Technology Guidance document
requires a minimum 2% slope (EPA, 1985).
-------
i
CTl
I *
So1' 'inar
Hf
[Bc|
I 1
Bd
Waste fill
tMHf
1_L
•Backfill (to)
a) TRENCH CONDITION
L,
v
Liner
Backfill (U>)
b) PROJECTING CONDITION
Equations for determining the vertical pressure acting on the pipe:
For TRENCH CONDITION:
°v = BduJCDt q( CUJ.
Where: C0- [l-e'2^ "/B"']
2Ku.
W • °v Be
For PROJECTING CONDITION:
DEFINITIONS:
aj = unit weight of backfill
«J|S unit weight of waste fill
Hfs height of waste fill
qfs vertical pressure at the bottom of the waste fill
av = vertical pressure at the top of the pipe
w •= force per unit length of pipe
z, - height of backfill above the pipe
Bd s width of trench
Be: outside diameter of pipe
K = lateral pressure coefficient of backfill
/A = coefficient of friction between backfill
and the wal1s
Figure 1-4. Pipe installation—conditions and loading (Clarke, 1968).
-------
where
qf = vertical pressure at the base of the unit due to waste
fill (Ib/sq ft),
uf = unit weight of the waste fill (Ib/cu ft); for example,
values range between 45 and 65 Ib/cu ft for municipal solid
waste with soil cover, and
Hf = height of waste fill (ft).
The value of the vertical pressure at the top of the pipe due to the
waste fill may be determined from the following equation:
The term CyS, a load coefficient, is a function of the ratio of the depth
of the trench, Z, (measured from the ground surface to the top of the pipe)
to the width of the trench, 84, and of the friction between the backfill
and the sides of the trench. It may be calculated from the following equa-
tion or obtained from Figure 1-5.
r _ -2Ky'(Z/Bd),
LyS " e
where
K = lateral pressure coefficient of the trench backfill,
y' = coefficient of friction between backfill and the walls of
the trench,
I = depth of trench from original ground surface to top of pipe
(ft), and
BJJ = width of trench at top of pipe (ft).
The product of Ky' is characteristic for a given combination of backfills in
natural (in place) soil. Maximum values for typical soils are presented in
ASCE Manual of Practice, No. 37. Those values of Ky' representing soils in
which flexible pipes are likely to be installed are:
Type of soil Maximum value of Ky'
Sand and gravel 0.165
Saturated top soil 0.150
Clay 0.130
Saturated clay 0.110
The value of the vertical pressure at the top of the pipe due to the trench
backfill may be determined from the following equation developed by Marston:
1-7
-------
u = unit weight of trench backfill (Ib/cu ft).
The term C;iSj£»
tei^^s^yji
0-02 OO3 0-05 0-07 0-10 0-20 0-30 050 070 1OO
LOAD COEFFICIENT,
Values of load coefficient Cus (trench uniform surcharge)
Figure 1-5. Trench condition—pipe load coefficient Cus (trench uniform
surcharge) (Clarke, 1968).
The total vertical pressure is equal to:
°v = avi + av;> = ^f cys + Bd u> C(
The force per unit length of the pipe is equal to:
W = av Bc>
1-8
-------
COEFFICIENT Cd (GRAPH ON LEFT)
1-0 1-52 345
0-10 0-15 0-20 0-25 0-3 04 0-5 0-6 07 VO 1-5
COEFFICIENT Cd (GRAPH ON RIGHT)
A—Cfor JEjt' = 0.19, for granular materials without cohesion
B—C,,for K\>! = 0.165 max. for sand and gravel
C—CjfoiKu' = 0.150 max. for saturated top soil
D—C,f for ATfi' = 0.130 ordinary max. for clay
E-C.iforX'u,'^ 0.110 max. for saturated clay
Values of load coefficient Ca (back fill)
Figure 1-6. Trench condition—pipe load coefficient C^ (Clarke, 1968).
1-9
-------
where
W = force per unit length of pipe, and
Bc = outside diameter of pipe.
1.2.2.2 Positive Projecting Condition (Figure 1-4) —
This condition is assumed to exist whenever the top of the pipe is at or
above the level of the bottom of the unit. In this case, the load on the
pipe can be assumed to be equal to the weight of a prism of overlying waste
fill with a width Bc and height Hf plus the weight of a similar prism of
gravel backfill above the pipe; because the pressure due to the gravel
backfill typically will be small compared to the pressure due to the waste
fill, the vertical pressure on the top of the pipe can be assumed to be equal
to the unit weight of the waste fill multiplied by the distance from top of
the waste fill to top of pipe, thus:
1.2.2.3 Perforated Pipe--
Perforations will reduce the effective length of pipe available to carry
loads and resist deflection. The effect of perforations can be taken into
account by using an increased load per nominal unit length of the pipe. If
lp equals the cumulative length in inches of perforations per foot of
pipe, the increased vertical stress to be used equals:
K)design »
1.2.3 Deflection
A well-accepted formula for calculating flexible pipe deflection under
earth loading is that developed by Spangler. This equation, also known as
the Iowa formula, is presented together with suggested values for its various
constants in the 1970 edition of the American Society of Civil Engineers
(ASCE) Manual of Practice, No. 37, Chapter 9, Section E, Subsection 1, and is
as follows:
ay -
El + 0.061 E'r3
where,
Ay = horizontal and vertical deflection of the pipe (in.),
De = a factor, generally taken at a conservative value of 1.5,
compensating for the lag or time dependent behavior of the
soil/pipe systems (dirnensionless),
1-10
-------
W = vertical load acting on the pipe per unit of pipe length
r = mean radius of the pipe (in.)»
E = modulus of elasticity of the pipe materials (psi),
E1 = modulus of passive soil resistance (psi) (normally estimated to
be 300 psi for soils of Proctor density of 65%, and 700 psi for
soils of Proctor density of at least 90%),
K = bedding constant, reflecting the support the pipe receives from
the bottom of the trench (dimensionless) (a conservative value
generally taken is 0.10), and
I = moment of inertia of pipe wall per unit of length (in.4/in.);
for any round pipe, I = t3/12 where t is the average thick-
ness (in).
The equation can be rewritten to express pipe deflection as a decimal frac-
tion of the pipe diameter, Bc, and to relate it to the vertical stress on
the pipe as follows:
_W_ - °v (Ay)(EI + O.OSlE'r3)
Bc " " (Bc)( DeKr3 )
Solutions to this equation are shown graphically in Fig. J-7 where the quant-
ity °v/(Ay/Bc) has been plotted against the passive soil modulus E1. The
relationship between CTv/(Ay/Bc) and E' has been shown for four plastic
pipes: 4 and 6-in. Schedule 40 and 4 and 6-in. Schedule 80 PVC pipe. In
computing the quantity El for these pipes, a reduced modulus was used to
account for creep of the plastic pipe. A value equal to 142,000 psi was used
to correspond to the modulus at 50 years under sustained loading (see Janson,
1974). Also shown is the relationship for El = 0. This would represent a
relationship between av/(Ay/Bc) and E1, if the stiffness of the pipe is
neglected.
In addition to using the chart to check the adequacy of a given pipe,
the chart can be used to determine the necessary value of EI/r^ which the
pipe must have for given values of ^max/(Ay/Bc) and E1. Although it is
customary to use either 300 or 700 psi for the value of the modulus of
passive soil resistance, it should be noted that the modulus of elasticity of
a coarse grained soil (sand or gravel) increases with increasing pressure (or
depth in the ground). Thus, it should be expected that the modulus of
passive soil resistance also would increase with increasing pressure or depth
of fill.
1-11
-------
\
V
3= 3.90 (6"dio. Sch.80PVC)
El/r':2.03 (4" dia. Sch. 40 PVC)
r'' 1.05 JJ/'.diix Sch-dP-P^£J
"7
Any pipe stiffness acceptable for values below this line)
-------
The term El in Spangler's equation reflects the pipe's contribution to
the total resistance to deflection under load offered by the pipe/soil
system. This term, known as the pipe's Stiffness Factor, is related to the
pipe's behavior under parallel plate loading as per ASTM D2412, "External
Loading Properties of Plastic Pipe by Parallel Plate Loading," by the follow-
ing expression:
El = 0.149r3(F/Ay),
where
E, I and r are as previously defined:
F = the recorded load (Ib/linear in.) required to produce a pipe
deflection Ay, and
Ay = the pipe's deflection (in.).
Minimum values of the term F/Ay, called Pipe Stiffness, are set accord-
ing to Pipe DR (dimension ratio) by the ASTM PVC Sewer Pipe Specifications
D3033 and D3034. The DR represents the ratio of the pipe's average outside
diameter to its minimum wall thickness. Thus, for each DR there is a cor-
responding minimum specified value of F/Ay.
The above expression for El can be substituted into the previous
equation for deflection to obtain the following:
gv = (0.149F/Wy) + 0.061E'.
Uy/Bc) D^K
Solutions to this equation can be made on a graph similar to Figure 1-7 where
the quantity CTv/(Ay/Bc) is plotted against the soil modulus E1 for
several values of F/Ay.
1.2.4 Buckling Capacity
The capacity of a buried plastic drain pipe to support vertical stresses
may be limited by buckling. Estimates of the vertical stresses at which
buckling of the 6-in. Schedule 40 PVC pipe (the most flexible of the four
pipes shown) will occur are indicated by the curve in Figure 1-7. For the
four pipes shown, buckling would not be a controlling factor. However, it
could be a controlling factor, depending on the flexibility of the pipe and
the modulus of passive soil resistance. Specific information for other sizes
and pipe materials proposed for use in the collection system should be
secured from the pipe manufacturer.
1.2.5 Compressive Strength
The capacity of the pipe to support vertical stresses may be influenced
by the circumferential compressive strength of the pipe. The designer or
1-13
-------
reviewer should secure up-to-date information on circumferential compres-
sive strength characteristics from the manufacturer of the type of pipe
proposed for use.
1.2.6 Construction Loadings
A pipe correctly designed to withstand loading from a high fill can fail
from loading received during construction. Although only a fraction of a
stationary wheel or tracked vehicle load applied at the ground surface over a
trench is transmitted to a pipe through the trench backfill, the percentage
increases rapidly as the vertical distance between the loaded surface and the
top of the pipe decreases. In addition, moving loads cause impact loading
which is generally considered to have a 1.5 to 2.0 multiplier effect over
stationary loading.
In general, equipment should not cross leachate collection drains in-
stalled in trenches with shallow cover or in projecting installations. When
equipment must be routed across a drain, impact loading can be minimized
by mounding material over the pipe to provide a vertical separation of 4 ft
between the loaded surface and the top of the pipe.
1.2.7 Procedures for Calculating Required Pipe Strength
The procedures used to select the proper strength pipe are illustrated
in the following examples:
Trench Installation (Figures 1-5 and 1-8)
Given: I = 1 ft - 8 in. Hf = 100 ft waste fill
B
-------
-
~
— Waste fill
i — Excavation subgrade
6" mln. — '
^^
C
• j » -
•» rvv, |
*»*»v
) ..«/"""
. *.l\ <
3ipe, perroraiea
r-Z'
Drain rock
Excavation elope
\
— *
^x<:>rr''i>*"
'•^
<
'VC oioe. barfnrntnd
Waste fill —
*-l
/ Drain rock
'*«^*^^ i
? ^>> T 1
•-••i/vS^ 1
' — 6" min.
—Waste fill
— 2 '-6"
PROJECTING INSTALLATIONS
Excavation slope
6"
-Drain rock
•4" PVC pipe, perforated
r-e"
TRENCH INSTALLATION
Figure 1-8. Typical leachate collection drains,
1-15
-------
From Fig. 1-5, CyS = 0.64 and Fig. 1-8, Cd = 0.9;
then
ov = (u)(Bd)(Cd) + (qf)(CyS)
= (110)(1.5)(0.9) + (5000)(0.64)
= 3348 psf = 23.3 psi = av max-
Step 2 - Select the appropriate modulus of passive soil
resistance E1 (psi). For gravel bedding use 300 to
700 psi.
Step 3 - Select allowable pipe deflection ratio Ay/Bc. Use
0.05 to 0.1.
Step4 " Determine the quantity ^ yg, where av max is in psi
From Fig. 1-7, the following information is obtained:
E1
Ay/Bc
0.05
0.1
CTv max/(Ay/&c)
466
233
300
4-in. Sch 80
adequate
4-in. Sch 40
4-in.
Sch
700
or 6-in.
80 adequate
or
6-in. Sch 80 Any pipe
adequate
Positive Projecting Installation (see Figures 1-4 and 1-8)
Given: l\ = 6 in.; other parameters given as in example above.
Determine: Required pipe strength/schedule.
Step 1 - Determine the maximum vertical pressure av(psi)
acting on the top of the pipe:
av = cofHf + uZi = (50)(100) + (110)(0.5) =
5055 psf = 35.1 psi = av max-
1-16
-------
Steps 2, 3, and 4 as given under Trench Installation.
From Fig. 1-7, the following information is obtained:
E1
AY/BC
0.05
0.1
CTv max/ (AY/Bc)
466
233
300
4-in. Sch 80
adequate
4-in. Sch 40
4-in.
Sch
700
or 6-in.
80 adequate
or
6-in. Sch 80
adequate
Any pipe
1.3 REFERENCES
ASCE and Water Pollution Control Federation. 1969. Design and Construction
of Sanitary and Storm Sewers. ASCE Manuals and Reports on Engineering
Practice No. 37. NY. 332 pp.
ASTM. Annual Book of ASTM Standards. American Society for Testing and
Materials, Philadelphia, PA. Issued annually in several parts:
D2112. "Test Method for Oxidation Stability of Inhibited Mineral
Insulating Oil by Rotating Bomb."
D3033. "Specification for Type PSP Poly(Vinyl Chloride) (PVC) Sewer
Pipe and Fittings."
D3034. "Specification for Type PSM Poly(Vinyl Chloride) (PVC) Sewer
Pipe and Fittings."
Cedergren, H.R. 1967. Seepage, Drainage, and Flow Nets. John Wiley and
Sons, Inc., NY. 534 pp.
Clarke, N. W. B. 1968. Buried Pipelines, A Manual of Structural Design and
Installation. Maclaren and Sons, London. 309 pp.
Janson, L. 1974. Plastic Pipe in Sanitary Engineering. Celanese Piping
Systems, Hillard, OH.
Spangler, M. G., and R. L. Handy. 1973. Soil Engineering. 3rd ed. Int.
Educational Publishers, NY. 748 pp.
1-17
-------
-------
APPENDIX J
ANALYSES OF HAZARDOUS WASTES USED
IN EXPOSURES REPORTED BY HAXO
This appendix summarizes the results of analyzing wastes used in the
exposure tests performed by Haxo et al (1985 and 1986). In these tests, a
variety of FMLs were exposed to a series of hazardous wastes under different
test conditions including exposure in one-sided exposure cells, tub tests,
pouch tests, and immersion tests. The results of these tests are summarized
in Chapter 5 in the following sections:
- Section 5.4.1.2, "Exposure to Hazardous Wastes in One-Sided Exposure
Cells."
- Section 5.4.1.4, "Exposure in Tub Tests."
- Section 5.4.1.6.2, "Tests of FML Pouches Containing Hazardous Waste
Liquids."
- Section 5.4.2.2, "Immersion of FMLs in Hazardous Wastes and Selected
Test Liquids."
The results of analyzing the wastes used in those exposure test are presented
in Table 1-1.
REFERENCES
ASTM. Annual Book of ASTM Standards. Issued annually in several parts.
American Society for Testing and Materials, Philadelphia, PA:
D92-85. "Test Method for Flash and Fire Points by Cleveland Open Cup,"
Sections 04.04, 05.01, and 10.03.
D2007-69. "Test Method for Characteristic Groups in Rubber Extender and
Processing Oils by the Clay-Gel Adsorption Chromatographic
Method," Sections 05.02, 09.01, and 10.03.
D2983-85. "Test Method for Low-Temperature Viscosity of Automotive
Fluid Lubricants Measured by Brookfield Viscometer," Section
05.02.
J-l
-------
TABLE J-l. ANALYSES OF HAZARDOUS WASTES USED IN EXPOSURES REPORTED BY HAXO
Wastes'
Acidic
"HFL"
Phases and tests (W-10)
Separation of phases
Phase I, aqueous
Insoluble organic
liquid, weight 1 0
Phase II, aqueous
phase, weight I 100
Phase III, solid
phase, weight % 0
Phase I - Organic
Weight J 0
Flash pointc, °C
Viscosity"), cP
At 20°C
At 30°C
Water content, % ...
Organic group6
Asphaltenes, I ...
Polar compounds, % ...
Saturated hydro-
carbons, T ...
Aroma tics, % ...
Lead, mg/L
Phase 11 - Aqueous
pH 3.3
Electrical conductivity,
ranho/cm 29
Weight I 100
Solids in solution, t
Total 2.48
Volatile 0.9
Solids, total g/L
Volatiles, g/L
Total dissolved, g/L ...
Volatiles dissolved, g/L
Total suspended, g/L ...
Volatiles suspended, g/L
Alkalinity, g CaC03/L
Oil and grease, g/L
Soluble volatile
organics, mL/L
Lead, mg/L ...
Phase III - Solids
Weight % 0
Flammabinty
Flame
Col or
Smoke
Solids. I
Organic, ...
Inorganic, t ...
Water extract, ng/g
pH
"HNOi-HF-
HOAc"b
(W-9)
0
100
0
0
...
...
...
...
. . .
...
...
...
...
1.1
155
100
0.77
0.12
140
15
137
7.0
15.0
9.0
...
0.0
0.0
28f
0
...
...
...
...
...
...
...
Alkaline
"Slop "Spent
Water" Caustic "b
(W-4) (W-2)
0 0
100 95.1
0 4.9
0 0
...
... ...
...
... ...
... ...
... ...
... ...
... ...
...
13.1 11.3
129 155
100 95.1
22.43 22.07
5.09 1.61
234.5
24.2
234.5
24.0
0.04
0.01
8.69
0.02
0.15
5.0*
0 4.9
Yes
Orange
No
8.9
91.1
122.4
5.2
"Lead "Slurry
Waste"b 011"
(H-14) (W-15)
10.4 98
86.2 0
3.4 2.0
10.4 98
<20 174
3200
660
0
13.1
14.0
13.1
59.7
530
7.6
...
86.2 0
0.9
0.35
3.23
1.62
2.66
1.14
0.41
0.28
1.06/28
0.15
1.0
13
3.4 2.0
... ...
... ...
... ...
22.5
77.5
43.8
7.4
Oily waste
"Oil Pond "Weed
104 "b Oil"
(W-5) (W-7)
89 20.6
0 78.4
11 0
89 20.6
157
300
124
17
9.6
18.6
37.9
339
170f
7.5
...
0 78.4
1.81
1.0
9.10
3.45
1.75
... ...
... ...
...
... ...
...
... ...
...
11.0 0
Yes
... ...
...
78.9
21.1
11.2
8.4
Pesti-
cide
"Weed
K1ller"b
(W-ll)
0
99.5
0.5
0
...
...
...
...
...
...
...
...
...
3.1
3.2
99.5
0.78
0.46
6.78
3.32
6.62
3.22
0.16
0.10
25
0.05
0.8
1.4*
0.5
Yes
Orange
No
50.4
49.6
3.5
2.5
•Matrecon waste serial number shown below Identification.
bAnalyzed after exposure. The "Oil Pond 104" waste was originally an oil-water slurry which eventually separated
Into oil and water layers. The Initial water content Has about 30%.
CASTM 092.
dASTM D2983.
"ASTM D2007-69, In percent fay weight.
*Total lead content of the waste.
Source: Haxo et al, 1985, p 26.
J-2
-------
Haxo, H. E., R. S. Haxo, N. A. Nelson, P. D. Haxo, R. M. White, and S.
Dakessian. 1985. Liner Materials Exposed to Hazardous and Toxic
Wastes. EPA-600/2-84/169 (NTIS No. PB 85-121-333). U.S. Environmental
Protection Agency, Cincinnati, OH. 256 pp.
Haxo, H. E., R. S. Haxo, N. A. Nelson, P. D. Haxo, R. M. White, and S.
Dakessian. 1986. Liner Materials Exposed to Toxic and Hazardous
Wastes. Waste Management and Research 4:247-264.
J-3
-------
-------
APPENDIX K
SUGGESTED PROPERTY STANDARDS FOR REPRESENTATIVE FMLS
AVAILABLE IN JULY 1988
In view of the lack of accepted standards to cover currently available
FMLs for lining waste disposal impoundments, suggested standards for repre-
sentative FMLs currently available (July 1988) are presented in this ap-
pendix. The values are preliminary and subject to change. They are based
largely upon the properties and tests discussed in Chapter 4, particular-
ly Section 4.2.2.5, and reflect some of the current efforts to develop
standards.
These tables of values should not be used to select materials. Selec-
tion, as indicated in Chapters 4, 5, 7, and 8, should be based upon factors
of compatibility, durability, etc. The tables are intended to be used as a
means of assuring that the quality of the FML that is installed in the waste
containment unit is the same as was tested in the compatibility tests.
The standards present values for different properties which can charac-
terize the FMLs. By themselves, these standards are not adequate to predict
long-term product performance, nor can they be used for engineering design
purposes. For example, the low temperature resistance numbers represent
qualities measured after a few minutes of exposure at a given temperature and
should not be interpreted or extrapolated into installation temperature
qualities or comparisons. Correlations of specific properties and tests with
field performance of lining materials have not been established, but the
results of the tests indicate the quality of the specific material under
test. Performance test methods are being developed by ASTM Committee D35 on
Geotextiles and Related Products for use in the design of containment
facilities.
K-l. GENERAL REQUIREMENTS FOR THE MANUFACTURE OF FMLS
FMLs shall be first quality designed and manufactured for the purpose of
lining waste disposal impoundments. They shall be manufactured of virgin
polymers and specifically compounded of high quality ingredients to produce
flexible, durable, watertight membranes. Compounding ingredients shall
either be soluble in the polymer or, if solid, shall pass through a No. 325
sieve, i.e. have particle size of 44 ym or less. All ingredients should be
well dispersed through the compound prior to being formed into membranes. No
water soluble ingredients can be used in the compound; neither can the
ingredients contain water-soluble components.
K-l
-------
The resultant FMLs shall be free from dirt, oil, foreign matter,
scratches, cracks, creases, bubbles, pits, tears, holes, pinholes, or other
defects that may affect serviceability and shall be uniform in color, thick-
ness, and surface texture. The sheeting shall be capable of being seamed
both in the factory and in the field to yield seams that are as resistant to
waste liquids as the sheeting.
Note: Recycling of clean scrap compound is allowed up to 5% by
weight of the compound. The recycling of scrap containing
fiber is generally not considered to be good practice;
however, the effects of such recycling have not been es-
tablished at this time and tests are underway to resolve
this question.
K-2. SUGGESTED TEST METHODS AND REQUIRED PROPERTIES
FOR REPRESENTATIVE LINERS
Suggested methods for testing FMLs for acceptance and quality control
and required values for properties of representative liner materials are
presented in the following six tables:
K-l. Suggested Properties and Methods for Testing of FMLs for
Standards and Specifications.
K-2. Titles of ASTM Test Methods Specifications Used with FMLs.
K-3. Suggested Standards for Unreinforced FMLs (Thermoplastic
FMLs of CPE, PVC, and PVC-OR).
K-4. Suggested Standards for Unreinforced FMLS (Polyethylene FMLs).
K-5. Suggested Standards for Fabric-Reinforced FMLs (FMLs with
Thermoplastic Coatings of CPE, CPE-A, and EIA).
K-6. Suggested Standards for Fabric-Reinforced FMLs (Thermoplastic
CSPE FMLs).
For quality control purposes, it is suggested that random samples be taken
from each 10,000 square yards of sheeting; however, a minimum of five samples
for quality control testing should be taken from each job. Each sample
should be three by six feet and should include a factory seam if the FML
requires factory fabrication. The minimum tests that should be performed for
quality control purposes are those that are listed under mechanical proper-
ties.
Table K-l presents all of the suggested test methods arranged by type
of FML and by analytical properties, mechanical properties, and tests of the
K-2
-------
TABLE K-l. SUGGESTED PROPERTIES AND METHODS' FOR TESTING FML5 FOR STANDARDS AND SPECIFICATIONS
Unreinforced FMLs
Property
Analytical properties
Specific gravity/density
Volatile loss
Extractables
Ash
Carbon black content
Carbon black dispersion
Melt index
Mechanical properties
Thickness:
Overall
Coating over scrim
Minimum tensile properties
(in both machine and
transverse directions):
Breaking strength of fabric
Breaking elongation of fabric
Tensile at yield
Elongation at yield
Tensile strength
Elongation at break
Modulus of elasticity
Tear strength
Hardness, Duro A or D
Hydrostatic resistance
Puncture resistance
Ply adhesion
Strength of factory seams:
Shear
Peel
Environmental and aging properties
Dimensional stability
Low temperature brittleness
Resistance to soil-burial for 120 d1
Tensile at yield
Tensile at fabric break
Tensile at break
Elongation at break
Modulus of elasticity
Ozone resistance at 40°C
Environmental stress-cracking
Water absorption
Hater extraction
Thermoplastic
polymers
D792, Method A
01203. Method A
MTH-lb
MTM-2b
D297, Section 34
na«
na
na
D1593, Section 9.1.3
na
na
na
na
na
D882. Methods A and B
D882, Methods A and B
na
D1004
D2240
0751, Method A,
Procedure 1
FTMS 101C,
Method 2065
na
D4545
D4545
D1204 (15 minutes
«t 100'C)
D17909
D3083, Section 9.5
na
na
D882
D882
na
D1149
100 pphm 03
701 extension
7 days
na
...
D3083, Section 9.6/
D1239
Semicrystal line
polymers
D792, Method A/D1505
01203. Method A
MTH-P
MTM-2b
D297, Section 34
TGA, D1603, or D4218
D3015
D1239, Procedure A
(Condition: 190/2.16)
D1593, Section 9.1.3
na
na
na
06 38
D638
D638
0638
D638 or
D882, Method A
D1004
D2240
D751, Method A,
Procedure 1
FTMS 101C,
Method 2065
na
D4545
D4545
D1204 (15 minute
at 100°C)
D746, Procedure B9
D3083, Section 9.5
0638
na
D638
D638
D638
D1149/D518
100 pphm 03
Bent loop
7 days
D1693
...
D3083, Section 9.6/
D1239
Fabric-reinforced FMLsb
D1203. Method A
MTM-1&
MTM-2t>.c
D297, Section 34 (selvage)
na
na
na
D751, Section 7
Optically*
D751, Method A (grab)
0751, Method A (grab)
na
na
0751, Method A (grab)
D751, Method A (grab)
na
0751, Method B (tongue)
(8 in. x 8 in. specimen)
D2240?
0751, Method A, Procedure 1
FTKS 101C, Method 2031
D413, Method A
04545
04 54 5
01204 (1 hour at 100'C)
D2136"
D3083, Section 9.5
na
D751, Method A (grab)
D751, Method A (grab)
D751, Method A (grab)
na
Dl 149/0518
100 pphm 03
Bent loop
7 days
na
D471
(166 hours at 23°C)
(166 hours at 70°C)
D3083, Section 9.6/
D1239
"ASTM unless otherwise noted. FTMS « Federal Test Method Standard; MTM • Matrecon Test Methods. Matrecon Test
Method 1 is presented in Appendix 6, and Matrecon Test Method 2 1s presented In Appendix E.
•"With thermoplastic coatings.
C8oth selvage edge and fabric-reinforced FML.
dna « not applicable.
•Optical measurements made of a diagonal cut of the FML made with a razor blade. A box microscope with stage
micrometer Kith mil divisions should be used.
fOn selvage edge.
SDeteminatlon of the temperature at which membranes exhibit brittle failure under specified Impact conditions.
"Bend specimen over 1/8-in. mandrel after four hours at the test temperature.
'Size of buried specimens: 1 in. x 6 Inches.
K-3
-------
TABLE K-2. TITLES OF ASTM TEST METHODS AND SPECIFICATION
USED WITH FMLS
ASTM number
Title and pertinent sections
D297-81
D412-80
D413-82
D471-79
D518-61 (1974)
D573-81
D624-73
D638-84
D746-79
D751-79
D792-66 (1979)
D882-83
D1004-66 (1981)
D1146-53 (1981)
D1149-86
D1203-67 (1981)
D1204-84
D1239-86
D1239-55 (1982)
Rubber Products - Chemical Analysis. Section 15-Density;
Section 34-Referee Ash Method.
Rubber Properties in Tension.
Rubber Property - Adhesion to Flexible Substrate.
Rubber Property - Effect of Liquids, Section 09.01.
Rubber Deterioration - Surface Cracking.
Rubber - Deterioration in Air Oven.
Rubber Property - Tear Resistance.
Tensile Properties of Plastics.
Brittleness Temperature of Plastics and Elastomers by
Impact.
Coated Fabrics.
Specific Gravity and Density of Plastics by Displacement.
Tensile Properties of Thin Plastic Sheeting.
Initial Tear Resistance of Plastic Film and Sheeting.
Blocking Point of Potentially Adhesive Layers.
Rubber Deterioration - Surface Ozone Cracking in a
Chamber (Flat Specimens).
Loss of Plasticizer from Plastics (Activated Carbon
Methods).
Linear Dimensional Changes of Nonrigid Thermoplastic
Sheeting or Film at Elevated Temperature.
Flow Rates of Thermoplastics by Extrusion Plastometer.
Resistance of Plastic Films to Extraction by Chemicals
continued . . .
K-4
-------
TABLE K-2. CONTINUED
ASTM number Title and pertinent sections
D1248-84 Specification for Polyethylene Plastics Molding and
Extrusion Materials.
D1505-85 Density of Plastics by the Density-Gradient Technique,
Section 08.01.
D1593-80 Specification for Nonrigid Vinyl Chloride Plastic
Sheeting.
D1603-76 (1983) Carbon Black in Olefin Plastics, Section 08.02.
D1693-70 (1980) Environmental Stress-Cracking of Ethylene Plastics.
D1790-62 (1983) Brittleness Temperature of Plastic Film by Impact.
D2136-66 (1984) Coated Fabrics - Low-Temperature Bend Test.
D2240-81 Rubber Property - Durometer Hardness.
D3015-72 (1985) Recommended Practice for Microscopical Examination of
Pigment Dispersion in Plastic Compounds.
D3083-76 (1980) Specification for Flexible Poly(Vinyl Chloride) Plastic
Sheeting for Pond, Canal, and Reservoir Lining; Section
9.5, Soil Burial, Section 9.6; Water Extraction; Section
9.4 Pinholes and Cracks, Section 04.04.
D4218-82 (1986) Carbon Black Content in Polyethylene Compounds by the
Muffle Furnace Technique.
D4545-86 Practice for Determining the Integrity of Factory
Seams Used in Joining Manufactured Flexible Sheet
Geomembranes.
aAs listed in the 1987 issue of the ASTM standards. Number in parentheses
indicates the year of last reapproval by the committee with jurisdiction
for the standard.
K-5
-------
TABLE K-3. SUGGESTED STANDARDS FOR UNREINFORCED FMLS
Thennoplastlc FMLs of Chlorinated Polyethylene. Polyvinyl Chloride, and Polyvlnyl Chloride - Oil-Resistant
Property
ASTM test methods
Chlorinated
polyethylene
Polyvlnyl chloride6
PVC-ORC
Nominal thickness, mil
Analytical properties
Specific gravity
Volatile loss, I (maximum)
Mechanical properties
Thickness:
Actual, mils (minimum)
Minimum tensile properties
in each direction:
Breaking factor, pp1 width
Elongation at break, %
Stress at 1001 elongation,
pp< width
Tear strength, Ib (minimum)
Factory seam strength
(minimum):
In shear (pp1)
In peel (ppi)
Hydrostatic resistance,
psi (minimum)
Environmental and aging
effects on properties
Dimensional stability,
1 change (maximum)
Low temperature (brlttleness
temperature), *F (maximum)
Resistance to soil-burial for
120 days (maximum % change
D792-A
D1203-A
01593, Section 9.1.3
0682
D1004
D4545/D3083/D8B2
D4545/D413
D751-A
01204
D1790
D3083
20
1.20
minimum
0.5
19
34
250
8
3.5
27
ID"
75
16
-20
30
1.20
minimum
0.5
28.5
20
1.24-1.30
range
0.9
19
30
1.24-1.30
range
0.7
28.5
40
1.24-130
range
0.55
42.75
43
300
12
4.5
46
(2300 psi)
300
18
(900 psi)
6.0
(300 pp1)
69
(2300 psi)
300
27
(900 psi)
8.0
(267 ppi)
92
(2300 psi)
300
36
(900 psi)
10.0
(250 ppi)
34
100
16
-20
36.8
10"
60
5
-15
55.2
82
5
-20
82.8
10"
95
5
-20
30
1.20
minimum
0.5
28.5
69
300
27
55.2
10<1
82
I I mil ui i^inoi value;.
Breaking factor
Elongation at break
Stress at 1001 elongation
Water extraction, I (maximum) D3083/D1239
5
20
20
-0.35
5
20
20
-0.35
5
20
10
-0.35
5
20
10
-0.35
5
20
10
-0.35
5
20
10
-0.35
"For more details regarding conditions and titles of test methods, see Tables K-l and K-2.
bFor waste containment purposes, the PVC FHL should be of single-ply construction, having polyvlnyV chloride as the sole
polymer. The resin used should be a medium to medium-high molecular weight PVC homopolymer with a relative viscosity of 2.25
to 2.50. The plasticizer should be a dlalkyl phthalate plastlcizer made from a minimum average of Cg molecular weight
alcohols. To ensure low volatiles, it is suggested that the minimum average molecular weight of the plasticizer should be
410. The specific gravity (at 20/20"C) of the plasticizer should be 0.964 to 0.972. and the refractive index (at 20*C) should
be 1.482 to 1.484. The PVC should be formulated to resist microbial attack. The PVC FML should be nonblocking in accordance
with ASTM Method D1146.
cPoly(v1nyl chloride) - oil resistant.
dOr film-tearing bond.
K-6
-------
TABLE K-4. SUGGESTED STANDARDS FOR UNREINFORCED FHLS
Polyethylene FMLs
Property
Nominal thickness, mil
Analytical properties
Density of base resin
Mechanical properties
Thickness^, mil (minimum)
Tensile properties, in each
direction (minimum):
Tensile at yield
Tensile strength
Modulus of elasticity, psi
(minimum)
Tear strength, Ib (minimum)
Hydrostatic resistance
Puncture resistance
(Shore D)
Bonded seam strength and
field seams:
In shear
In peel
Environmental and aging
effects on properties
Dimensional stabilityd,
% change (maximum)
temperature), °F (maximum)
Resistance to soil-burial for
120 days (maximum % change
from original value):
Elongation at yield
Elongation at break
hours, (minimum)
change (maximum)
Polyethylene
Test method3 base compound
30-120
D1593, Section 9.1.3
D638
2500 psi
4000 psi
D1004, Die C 750
D751, Method A 8000
FTMS 101C, Method 2065
D4545
DI204 3
D3083
FMLs of different nominal thickness
30 40 60 80 100
27 36 52 72 90
75 90 150 200 250
120 160 240 320 400
22 30 45 60 75
240 315 490 650 800
50 60 85 110 135
FTBC FTBC FTBC FTBC FTBC
FTBC FTBC FTBC FTBC FTBC
33333
aASTM unless otherwise noted. ASTM « American Society for Testing Materials; FTMS • Federal Test Method Standard.
For more details regarding conditions and titles of test methods, see Tables K-l and K-2.
bTo ensure that the minimum thickness requirements are met, it Is suggested that the thickness be measured at
each foot across the FML sheet at the beginning and end of each roll.
cSee Appendix N for location of break codes for the testing of seam strength; FTB « film tearing bond.
^Maximum percent change in each direction in 15 min at 100°C.
eNo cracks were visible at 7X magnification on bent loops exposed for 7 days in 100 pphm 03.
K-7
-------
TABLE K-5. SUGGESTED STANDARDS FOR FABRIC-REINFORCED FMLS
FMLs with Thermoplastic Coatings of Chlorinated Polyethylene (CPE),
Chlorinated Polyethylene-Alloy, (CPE-A) and Ethylene Interpolymer Alloy (EIA)
Property
Nominal thickness, mil
Analytical properties
Volatile loss, I (maximum)
Mechanical properties
Thickness:
Overall1, mil (minimum)
Coating over fabric,
mils (minimum)
Minimum tensile properties
(each direction) :
Breaking strength, Ib
Tear resistance, Ib (minimum)
Hydrostatic resistance,
psi (minimum)
Ply adhesion (each direction),
Ib/in width (minimum)
Factory seam strength (minimum):
In shear (Ib)
In peel (ppi)
ASTM test method"
D1203, Method A
D751
Optically
D751-A (grab)
D751-B
0751-A, Procedure 1
D413-A
D751, Modified"
D413
36"
0.5
32
11
120
25
160
10"
10>
CPE
36b
0.5
34
11
200
35
250
8d
160
10f
45
0.5
41
11
200
75
300
8"
160
10f
CPE-A
36 45
0.7 0.7
34 41
11 11
200 250
60 70
250 250
7" ?d
160 176
10f 10'
EIA
30
1.0
27
7
400
125
500
lOd
320
Environmental and aging
effects on properties
Dimensional stability (each
direction), I change (maximum)
Low temperature (brittleness
temperature), °F (maximum)
Tear resistance after air-oven
aging for 30 days at 100°C
Ib (minimum)
Resistance to soil-burial for
120 days (maximum t change
from original value):
01204
D21369
D753/D751-B
D3083
22222 2
-40 -40 -40 -40 -40 -30
20 25 25 25 25 90
Breaking strength of fabric alone6
Breaking factor of unrein-
forced FML
Elongation at break of
unreinforced FML
Stress at 1001 elongation of
unreinforced FML
Ozone resistance at 40°C D1149/D518
(Bent loop at 100 pphm 03
for 7 days)
Water extraction, I (maximum) D3083
Water absorption, % gain (maximum): D471
14 days at 23*C
14 days at 70°C
-25 -25 -25 -25 -25 -25
-5 -5 -5 -5 -5 -10
-20 -20 -20 -20 -20 -20
+ 10 +10 +25 +25 +25 +1B
cracks"
-0.35 -0.35 -0.35
... 1
2
aFor more details regarding conditions and titles of test methods, see Tables K-l and K-2.
t>These FMLs differ in their fabric reinforcement.
cTo better ensure that the required thickness of the FKL 1s achieved, it is recommented that thickness
measurements of the FML be made very 6-in. across the width of the manufactured sheeting at the beginning
and end of each roll.
<*0r film-tearing bond.
Measured at 12 inches-per-minute, specimen 4-in. wide and with 4 1/2-in. on either side of seam.
^Or ply separation in plane of the fabric.
9l/8-in. Mandrel after 4 hours exposure at -40°C.
"No cracks were visible at 7X magnification.
K-8
-------
TABLE K-6. SUGGESTED STANDARDS FOR FABRIC-REINFORCED FMLS
Thermoplastic Chlorosulfonated Polyethylene (CSPE) FMLs
Potable and Industrial Grades'
CSPE FKL-type
Property
ASTM test methodb
C
45
Nominal thickness, mil
Analytical properties
Volatile loss. X (maximum)
Mechanical properties
Thickness:
Actual, mil (minimum)
Actual coating over scrim,
mil (minimum)
Minimum tensile properties
(each direction):
Breaking strength of
fabric, Ibf
Tensile strength of un-
relnforced FHL, Ibf
Elongation at break of
unrelnfcrced FML, I
Tear resistance, Ibf (minimum)
Hydrostatic resistance,
psi (minimum)
Ply adhesion (each direction),
ppi (minimum)
Factory seam strength (minimum):
In shear, Ibf
In peel, ppi
30 36
36
D1203
D751
Optically
D751-A (Grab)
0412
D412
D751-B
D751-A, Procedure 1
D413-A
D751, Modified*
D413
27
11
80
10f
27
11
10 10
45
0.5 0.5 0.5 0.5
34 41
11 11
60C 120 200 125
1200 1200 1200 1200
1500
-------
effects of environmental and aging conditions on properties. The types of
polymeric FMLs are:
- Thermoplastic FMLs without fabric reinforcement.
- Semi crystal line FMLs without fabric reinforcement.
-Fabric-reinforced FMLs which include both FMLs with crosslinked
coatings and those with thermoplastic coatings.
Note 1. No fabric-reinforced FMLs with crystalline coatings
are currently available in thicknesses of 20 mils or
greater.
Note 2. Inasmuch as crosslinked FMLs are not being produced or
used for the lining of waste containment facilities
suggested standards for these materials are not in-
cluded.
Table K-2 lists the ASTM standards that are suggested for testing and
evaluation of the FMLs. These methods are listed by number, giving their
titles. Those that are practices or specifications are indicated; the rest
are test methods.
Table K-3 presents the suggested standards for unreinforced FMLs based
on thermoplastic polymer compositions, exclusive of polyethylene. The
thermoplastic FMLs that are included in the table are based on CPE, PVC, and
PVC-OR.
Table K-4 covers the suggested standards for polyethylene FMLs, which
are available in thicknesses from 20 to 120 mils. For FMLs of polyethylene
suggested values for properties, such as tensile at yield, tensile strength,
tear resistance, and seam strength, vary proportionately with the thickness.
Other properties such as specific gravity, volatile loss, elongation at
yield, elongation at break, modulus of elasticity, dimensional stability,
low temperature brittleness, resistance to soil-burial, ozone resistance,
resistance to environmental stress-cracking, and water extraction are com-
pound properties and are considered for these standards to be independent of
the thickness of the FML.
Note: Inasmuch as the polyethylene used in the manufacture of
FMLs is not high density by standard practice in the
plastics industry, the term "high density" is not used.
"High-density" polyethylene has a density of 0.941 and
higher (see Chapter 4, Section 4.2.2.1.4).
Tables K-5 and K-6 present the suggested standards for representative
fabric-reinforced flexible polymeric FMLs. Strength values for these FMLs
depend upon the fabric reinforcement used. Fabric reinforcement increases
K-10
-------
tensile strength, puncture resistance and tear resistance, and reduces
shrinkage and elongation at break. Table K-5 covers those FMLs coated with
thermoplastic chlorinated polyethylene and with ethylene interpolymer
alloy. Table K-6 covers fabric-reinforced chlorosulfonated polyethylene
lining materials. It covers both standard (potable grade) CSPE coated
FMLs and the industrial grade of CSPE coating which has a lower water
absorption than the standard grade. Minimum required values for potable and
industrial-grade CSPE FMLs are equal except for breaking strength, strength
of factory seams, and water absorption. Of particular importance in the
assessing of fabric-reinforced FMLs is the adhesion between the top and
bottom plies and the thickness of the coating above the fabric.
No required values are suggested for seam strength by dead weight test
because of the lack of data. Dead weight tests are considered to be im-
portant for assessing adhesion in seams made both in the factory and in
the field. These tests are particularly useful in assessing the durability
of seams, as they keep the seam in the test specimen under constant load.
ASTM Test Methods D413, "Adhesion to Flexible Substrate (Machine Method)"
and D1876, "Peel Resistance of Adhesives (T-Peel Test)" appear to be the
appropriate test methods for assessing peel strength of liner seams.
K-ll
-------
-------
APPENDIX L
METHOD 9090 COMPATIBILITY TEST
FOR WASTES AND MEMBRANE LINERS
L-l
-------
METHOD 9090
COMPATIBILITY TEST FOR WASTES AND MEMBRANE LINERS
1.0 SCOPE AND APPLICATION
1.1 Method 9090 1s Intended for use 1n determining the effects of
chemicals 1n a surface Impoundment, waste pile, or landfill on the physical
properties of flexible membrane liner (FML) materials Intended to contain
them. Data from these tests will assist 1n deciding whether a given Uner
material 1s acceptable for the Intended application.
2.0 SUMMARY OF METHOD
2.1 In order to estimate waste/Hner compatibility, the Uner material
1s Immersed 1n the chemical environment for minimum periods of 120 days at
room temperature (23 + 2*C) and at 50 + 2*C. In cases where the FML will be
used 1n a chemical environment at elevated temperatures, the immersion testing
shall be run at the elevated temperatures 1f they are expected to be higher
than 50*C. Whenever possible, the use of longer exposure times 1s
recommended. Comparison of measurements of the membrane's physical
properties, taken periodically before and after contact with the waste fluid,
1s used to estimate the compatibility of the Uner with the waste over time.
3.0 INTERFERENCES (Not Applicable)
4.0 APPARATUS AND MATERIALS
NOTE: In general, the following definitions will be used 1n this method:
1. Sample — a representative piece of the Uner material proposed for
use that 1s of sufficient size to allow for the removal of
all necessary specimens.
2. Specimen ~ a piece of material, cut from a sample, appropriately
shaped and prepared so that 1t 1s ready to use for a test.
4.1 Exposure tank; Of a size sufficient to contain the samples, with
provisions for supporting the samples so that they do not touch the bottom or
sides of the tank or each other, and for stirring the liquid 1n the tank. The
tank should be compatible with the waste fluid and Impermeable to any of the
constituents they are Intended to contain. The tank shall be equipped with a
means for maintaining the solution at room temperature (23 + 2* C) and 50 +
2*C and for preventing evaporation of the solution (e.g., use a cover equipped"
with a reflux condenser, or seal the tank with a Teflon gasket and use an
airtight cover). Both sides of the Uner material shall be exposed to the
chemical environment. The pressure Inside the tank must be the same as that
outside the tank. If the Uner has a side that (1) 1s not exposed to the
9090 - 1
Revision 0
Date September 1986
1-2
-------
waste 1n actual use and (2) 1s not designed to withstand exposure to the
chemical environment, then such a liner may be treated with only the barrier
surface exposed.
4.2 Stress-strain machine suitable for measuring elongation, tensile
strength, tear resistance, puncture resistance, modulus of elasticity, and ply
adhesion.
4.3 Jig for testing puncture resistance for use with FTMS 101C, Method
2065.
4.4 Liner sample labels and holders made of materials known to be
resistant to the specific wastes.
4.5 Oven at 105 + 2«C.
4.6 Dial micrometer.
4.7 Analytical balance.
4.8 Apparatus for determining extractable content of Uner materials.
NOTE: A minimum quantity of representative waste fluid necessary to
conduct this test has not been specified 1n this method because
the amount will vary depending upon the waste compost1on and the
type of Uner material. For example, certain organic waste
constituents, 1f present 1n the representative waste fluid, can be
absorbed by the Uner material, thereby changing the concentration
of the chemicals 1n the waste. This change in waste composition
may require the waste fluid to be replaced at least monthly 1n
order to maintain representative conditions 1n the waste fluid.
The amount of waste fluid necessary to maintain representative
waste conditions will depend on factors such as the volume of
constituents absorbed by the specific liner material and the
concentration of the chemical constituents 1n the waste.
5.0 REAGENTS (Not Applicable)
6.0 SAMPLE COLLECTION, PRESERVATION, AND HANDLING
6.1 For information on what constitutes a representative sample of the
waste fluid, refer to the following guidance document:
Permit Applicants' Guidance Manual for Hazardous Waste Land Treatment,
Storage, and Disposal Facilities; Final Draft; Chap. 5, pp. 15-17;
Chap. 6, pp. 18-21; and Chap. 8, pp. 13-16, May 1984.
9090 - 2
Revision 0
Date September 1986
L-3
-------
7.0 PROCEDURE
7.1 Obtain a representative sample of the waste fluid. If a waste
sample 1s received 1n more than one container, blend thoroughly. Note any
signs of stratification. If stratification exists, Uner samples must be
placed 1n each of the phases. In cases where the waste fluid 1s expected to
stratify and the phases cannot be separated, the number of Immersed samples
per exposure period can be Increased (e.g., 1f the waste fluid has two phases,
then 2 samples per exposure period are needed) so that test samples exposed at
each level of the waste can be tested. If the waste to be contained 1n the
land disposal unit 1s 1n solid form, generate a synthetic leachate (See Step
7.9.1).
7.2 Perform the following tests on unexposed samples of the polymeric
membrane liner material at 23 + 2*C and 50 + 2*C (see Steps 7.9.2 and 7.9.3
below for additional tests suggested for specific circumstances). Tests for
tear resistance and tensile properties are to be performed according to the
protocols referenced 1n Table 1. See Figure 1 for cutting patterns for
nonrelnforced liners, Figure 2 for cutting patterns for reinforced liners, and
Figure 3 for cutting patterns for semi crystal line liners. (Table 2, at the end
of this method, gives characteristics of various polymeric Uner materials.)
1. Tear resistance, machine and transverse directions, three specimens
each direction for nonrelnforced liner materials only. See Table 1
for appropriate test method, the recommended test speed, and the
values to be reported.
2. Puncture resistance, two specimens, FTMS 101C, Method 2065. See
Figure 1, 2, or 3, as applicable, for sample cutting patterns.
3. Tensile properties, machine and transverse directions, three tensile
specimens 1n each direction. See Table 1 for appropriate test
method, the recommended test speed, and the values to be reported.
See Figure 4 for tensile dumbbell cutting pattern dimensions for
nonrelnforced Uner samples.
4. Hardness, three specimens, Duro A (Duro D 1f Duro A reading 1s
greater than 80), ASTM D2240. The hardness specimen thickness for
Duro A 1s 1/4 1n., and for Ouro D 1t 1s 1/8 1n. The specimen
dimensions are 1 1n. by 1 1n.
5. Elongation at break. This test 1s to be performed only on membrane
materials that do not have a fabric or other nonelastomerlc support
as part of the Uner.
6. Modulus of elasticity, machine and transverse directions, two
specimens each direction for semi crystalline Uner materials only,
ASTM 0882 modified Method A (see Table 1).
7. YolatHes content, SW 870, Appendix III-O.
8. Extractables content, SW 870, Appendix III-E.
9090 - 3
Revision 0
Date September 1986
L-4
-------
TABLE 1. PHYSICAL TESTING OF EXPOSED MEMBRANES IN LINER-WASTE LIQUID COMPATIBILITY TEST
10
o
to
o
I
en
O 70
(u n
rt <
n> -*•
1/1
»/> o
0) 3
o
Type of compound and
construction
Tensile properties
Method
Type of specimen
Number of specimens
Speed of test
Values to be reported
Modulus of elasticity
Method
Type of specimen
Number of specimens
Speed of test
Values reported
Tear resistance
Method
Type of specimen
Number of specimens
Speed of test
Values reported
Puncture resistance
Method
Type of specimen
Number of specimens
Speed of test
Values reported
Crosslinked or vulcanized
ASTM 0412
Dumbbell"
3 In each direction
20 ipm
Tensile strength, psi
Elongation at break. X
Tensile set after break. 1
Stress at 100 and 2001
elongation, psi
c
...
...
...
ASTN D624
Die C
3 in each direction
20 1pm
Stress, ppi
FTHS 101C. Method 2065
2-1 n. square
2
20 1pm
Gage, mil
Stress, Ib
Elongation. In.
Thermoplastic
ASTM 0638
Dumb be lib
3 In each direction
20 1pm
Tensile strength, psi
Elongation at break, I
Tensile set after break, I
Stress at 100 and 2001
elongation, psi
c
...
...
...
...
ASTM D1004
e
3 in each direction
20 1pm
Stress, ppi
FTMS 101C. Method 2065
2-1 n. square
2
20 Ipm
Gage, mil
Stress, Ib
Elongation, in.
Semi-
crystalllne
ASTN D638
DumbbellD
3 in each direction
2 1pm
Tensile stress at yield, psi
Elongation at yield. X
Tensile strength at break, psi
Elongation it break, I
Tensile set after break, I
Stress at 100 and 2001
elongation, psi
ASTM D882, Htd A
Strip: O.S-ln. Hide and
6-1n. long at a 2-1n.
Jan separation
2 In each direction
0.2 1pm
Greatest slope of initial
stress-strain curve, psi
ASTM D1004
e
2 In each direction
2 1pm
Maximum stress, ppi
FTMS 101C, Method 2065
2-1 n. square
2
20 1pm
Gage, mil
Stress, Ib
Elongation, in.
Fabrlc-rel nf orced*
ASTM D7S1, Htd B
1-in. nlde strip and
2- In. Jan separation
3 In each direction
12 1pm
Tensile at fabric break, ppi
Elongation at fabric break, »
Tensile at ultimate break, ppi
Elongation at ultimate break. I
Tensile set after break, I
Stress at 100 and 2001
elongation, ppi
c
...
...
...
d
...
...
...
...
FTMS 101C, Method 2065
2-1 n. square
2
20 1pm
Gage, mil
Stress, Ib
Elongation, In.
'Can be thermoplastic, cross)inked or vulcanized membrane.
bSee Figure 3.
cNot performed on this material.
dNo tear resistance test Is recommended for fabric-reinforced sheetings in the 1m
eSame as ASTM D624, Die C.
erston study.
-------
A
10"
Puncture test specimens
Tear test specimens
Volatlles test specimen
Tensile test specimens
Figure 1. Suggested pattern for cutting test specimens from
nonreinforced cross!inked or thermoplastic immersed
liner samples.
9090 - 5
Revision 0
Date September 1986
L-6
-------
Volatiles test specimen
Puncture test specimens
Ply adhesion test specimens
Tensile test specimens
c
o
u
-------
Modulus of elasticity
test specimens
Tensile test specimens
Volatiles test specimen
Puncture test specimens
Figure 3. Suggested pattern for cutting test specimens from
semi crystalline immersed liner samples. Note: To
avoid edge effects, cut specimens 1/8 - 1/4 inch
in from edge of immersed sample.
9090 - 7
Revision 0
Date SeotemOer 1986
L-8
-------
t
wo
1
\
"^v^
^
\
w
T
i n
x^
\
W - Width of narrow section
L - Length of narrow section
WO - Width overall
LO - Length overal1
G - Gage length
D - Distance between grips
0.25 inches
1.25 inches
0.625 inches
3.50 inches
1.00 inches
2.00 inches
Figure 4. Die for tensile dumbbell (nonreinforced
liners) having the following dimensions.
9090 - 8
Revision 0
Date Septemoer 1986
L-9
-------
9. Specific gravity, three specimens, ASTM D792 Method A.
10. Ply adhesion, machine and transverse directions, two specimens each
direction for fabric reinforced liner materials only, ASTM D413
Machine Method, Type A — 180 degree peel.
11. Hydrostatic resistance test, ASTM D751 Method A, Procedure 1.
7.3 For each test condition, cut five pieces of the lining material of a
size to fit the sample holder, or at least 8 In. by 10 1n. The fifth sample
1s an extra sample. Inspect all samples for flaws and discard unsatisfactory
ones. Liner materials with fabric reinforcement require close Inspection to
ensure that threads of the samples are evenly spaced and straight at 90*.
Samples containing a fiber scrim support may be flood-coated along the exposed
edges with a solution recommended by the Hner manufacturer, or another
procedure should be used to prevent the scrim from being directly exposed.
The flood-coating solution will typically contain 5-15X solids dissolved 1n a
solvent. The solids content can be the Hner formula or the base polymer.
Measure the following:
1. Gauge thickness, 1n. — average of the four corners.
2. Mass, Ib. — to one-hundredth of a Ib.
3. Length, In. — average of the lengths of the two sides plus the
length measured through the Hner center.
4. Width, 1n. — average of the widths of the two ends plus the width
measured through the Hner center.
NOTE: Do not cut these Hner samples Into the test specimen shapes shown
1n Figure 1, 2, or 3 at this time. Test specimens will be cut as
specified 1n 7.7, after exposure to the waste fluid.
7.4 Label the liner samples (e.g., notch or use metal staples to
Identify the sample) and hang 1n the waste fluid by a wire hanger or a weight.
Different Hner materials should be Immersed 1n separate tanks to avoid
exchange of plastldzers and soluble constituents when plastlclzed membranes
are being tested. Expose the Hner samples to the stirred waste fluid held at
room temperature and at 50 + 2*C.
7.5 At the end of 30, 60, 90, and 120 days of exposure, remove one liner
sample from each test condition to determine the membrane's physical
properties (see Steps 7.6 and 7.7). Allow the Uner sample to cool 1n the
waste fluid until the waste fluid has a stable room temperature. Wipe off as
much waste as possible and rinse briefly with water. Place wet sample 1n a
labeled polyethylene bag or aluminum' foil to prevent the sample from drying
out. The liner sample should be tested as soon as possible after removal from
the waste fluid at room temperature, but 1n no case later than 24 hr after
removal.
9090 - 9
Revision 0
Date September 1986
L-10
-------
7.6 To test the Immersed sample, wipe off any remaining waste and rinse
with delonlzed water. Blot sample dry and measure the following as 1n Step
7.3:
1. Gauge thickness, 1n.
2. Mass, Ib.
3. Length, 1n.
4. Width, 1n.
7.7 Perform the following tests on the exposed samples (see Steps 7.9.2
and 7.9.3 below for additional tests suggested for specific circumstances).
Tests for tear resistance and tensile properties are to be performed according
to the protocols referenced 1n Table 1. Die-cut test specimens following
suggested cutting patterns. See Figure 1 for cutting patterns for
nonrelnforced liners, Figure 2 for cutting patterns for reinforced liners, and
Figure 3 for semi crystalline liners.
1. Tear resistance, machine and transverse directions, three specimens
each direction for materials without fabric reinforcement. See Table 1 for
appropriate test method, the recommended test specimen and speed of test, and
the values to be reported.
2. Puncture resistance, two specimens, FTMS 101C, Method 2065. See
Figure 1, 2, or 3, as applicable, for sample cutting patterns.
3. Tensile properties, machine and transverse directions, three
specimens each direction. See Table 1 for appropriate test method, the
recommended test specimen and speed of test, and the values to be reported.
See Figure 4 for tensile dumbbell cutting pattern dimensions for nonrelnforced
liner samples.
4. Hardness, three specimens, Duro A (Duro D If Duro A reading 1s
greater than 80), ASTM 2240. The hardness specimen thickness for Duro A 1s
1/4 1n., and for Duro D 1s 1/8 1n. The specimen dimensions are 1 1n. by 1 1n.
5. Elongation at break. This test 1s to be performed only on membrane
materials that do not have a fabric or other nonelastomeric support as part of
the Uner.
6. Modulus of elasticity, machine and transverse directions, two
specimens each direction for semi crystalline Uner materials only, ASTM D882
modified Method A (see Table 1).
7. VolatHes content, SW 870, Appendix III-D.
8. Extractables content, SW 870, Appendix III-E.
9090 - 10
Revision
Date September 1986
L-ll
-------
9. Ply adhesion, machine and transverse directions, two specimens each
direction for fabric reinforced Uner materials only, ASTM D413 Machine
Method, Type A — 180 degree peel.
10. Hydrostatic resistance test, ASTM D751 Method A, Procedure 1.
7.8 Results and reporting:
7.8.1 Plot the curve for each property over the time period 0 to
120 days and display the spread 1n data points.
7.8.2 Report all raw, tabulated, and plotted data. Recommended
methods for collecting and presenting Information are described 1n the
documents listed under Step 6.1 and 1n related agency guidance manuals.
7.8.3 Summarize the raw test results as follows:
1. Percent change 1n thickness.
2. Percent change 1n mass.
3. Percent change 1n area (provide length and width dimensions).
4. Percent retention of physical properties.
5. Change, 1n points, of hardness reading.
6. The.modulus of elasticity calculated In pounds-force per
square Inch.
7. Percent volatlles of unexposed and exposed Uner material.
8. Percent extractables of unexposed and exposed Uner material.
9. The adhesion value, determined 1n accordance with ASTM D413,
Section 12.2.
10. The pressure and time elapsed at the first appearance of
water through the flexible membrane Uner for the hydrostatic
resistance test.
7.9 The following additional procedures are suggested In specific
situations:
7.9.1 For the generation of a synthetic leachate, the Agency
suggests the use of the Toxldty Characteristic Leaching Procedure (TCLP)
that was proposed 1n the Federal Register on June 13, 1986, Vol. 51, No.
114, p. 21685.
7.9.2 For semi crystalline membrane liners, the Agency suggests the
determination of the potential for environmental stress cracking. The
9090 - 11
Revision
Date September 1986
L-12
-------
test that can be used to make this determination 1s either ASTM D1693 or
the National Bureau of Standards Constant Tensile Load. The evaluation
of the results should be provided by an expert 1n this field.
7.9.3 For field seams, the Agency suggests the determination of
seam strength 1n shear and peel modes. To determine seam strength 1n
peel mode, the test ASTM 0413 can be used. To determine seam strength 1n
shear mode for nonrelnforced FMLs, the test ASTM D3083 can be used, and
for reinforced FMLs, the test ASTM 0751, Grab Method, can be used at a
speed of 12 In. per m1n. The evaluation of the results should be
provided by an expert 1n this field.
8.0 QUALITY CONTROL
8.1 Determine the mechanical properties of Identical nonlmmersed and
Immersed Uner samples 1n accordance with the standard methods for the
specific physical property test. Conduct mechanical property tests on
nonlmmersed and Immersed Uner samples prepared from the same sample or lot of
material 1n the same manner and run under Identical conditions. Test Uner
samples Immediately after they are removed from the room temperature test
solution.
9.0 METHOD PERFORMANCE
9.1 No data provided.
10.0 REFERENCES
10.1 None required.
9090 - 12
Revision
Date September 1986
L-13
-------
TABLE 2. POLYMERS USED IN FLEXIBLE MEMBRANE LINERS
Thermoplastic Materials (TP)
CPE (Chlorinated polyethylene)4
A family of polymers produced by a chemical reaction of chlorine on
polyethylene. The resulting thermoplastic elastomers contain 25 to 45%
chlorine by weight and 0 to 25X crystal Unity.
CSPE (Chlorosulfonated polyethylene)3
A family of polymers that are produced by the reaction of polyethylene
with chlorine and sulfur dioxide, usually containing 25 to 43X chlorine
and 1.0 to 1.4X sulfur. Chlorosulfonated polyethylene 1s also known as
hypalon.
EIA (Ethylene Interpolymer alloy)a
A blend of EVA and polyvlnyl chloride resulting 1n a thermoplastic
elastomer.
PVC (Polyvlnyl chloride)8
A synthetic thermoplastic polymer made by polymerizing vinyl chloride
monomer or vinyl chloride/vinyl acetate monomers. Normally rigid and
containing SOX of plastlclzers.
PVC-CPE (Polyvlnyl chloride - chlorinated polyethylene alloy)*
A blend of polyvlnyl chloride and chlorinated polyethylene.
TN-PVC (Thermoplastic n1tr1le-polyv1nyl cholor1de)a
An alloy of thermoplastic unvulcanlzed nltrlle rubber and polyvlnyl
chloride.
Vulcanized Materials (XL)
Butyl rubber*
A synthetic rubber based on Isobutylene and a small amount of Isoprene to
provide sites for vulcanization.
aAlso supplied reinforced with fabric.
9090 - 13
Revision
Date September 1986
L-14
-------
TABLE 2. (Continued)
EPOM (Ethylene propylene dlene monomer)a'b
A synthetic elastomer based on ethylene, propylene, and a small amount of
nonconjugated dlene to provide sites for vulcanization.
CM (Cross-linked chlorinated polyethylene)
No definition available by EPA.
CO, ECO (Ep1cHlorohydr1n polymers)3
Synthetic rubber, Including two ep1chlorohydr1n-based elastomers that are
saturated, hlgh-molecular-welght aliphatic polyethers with chloromethyl
side chains. The two types Include homopolymer (CO) and a copolymer of
eplchlorohydrln and ethylene oxide (ECO).
CR (Polychloroprene)*
Generic name for a synthetic rubber based primarily on chlorobutadlene.
Polychloroprene 1s also known as neoprene.
Semi crystalline Materials (CX)
HOPE - (High-density polyethylene)
A polymer prepared by the low-pressure polymerization of ethylene as
the principal monomer.
HOPE - A (High-density polyethylene/rubber alloy)
A blend of high-density polyethylene and rubber.
LLDPE (Liner low-density polyethylene)
A low-density polyethylene produced by the copolymerlzatlon of ethylene
with various alpha oleflns 1n the presence of suitable catalysts.
PEL (Polyester elastomer)
A segmented thermoplastic copolyester elastomer containing recurring
long-chain ester units derived from dlcarboxyllc adds and long-chain
glycols and short-chain ester units derived from dlcarboxyllc acids and
Iow-fflolecular-we1ght dlols.
*A1so supplied reinforced with fabric.
"Also supplied as a thermoplastic.
9090 - 14
Revision
Date September 1986
L-15
-------
TABLE 2. (Continued)
PE-EP-A (Polyethylene ethylene/propylene alloy)
A blend of polyethylene and ethylene and propylene polymer resulting 1n a
thermoplastic elastomer.
T-EPOM (Thermoplastic EPOM)
An ethylene-propylene dlene monomer blend resulting 1n a thermoplastic
elastomer.
9090 - 15
Revision
Date September 1986
L-16
-------
MCTHOQ 9O90
COMPATIBILITY TEST FOR HASTES AND MEMBRANE LINERS
7. i
o
OBtvln •aapl«
of Haste fluio
7.9 Determine
pnysical
properties «e
SO o«v
tnt«i-v«i«
7.2
taste on
•••ol«* or
liner »»terl»l
7.3
7.6
To te«c
•xposed
••••urc g«uoc
nicnn«m«. ••••.
l«ngtr>. wiatn
Cut
oi«c«« or
lining naterl*!
for «*cn test
conoitlon
7.4
7.7
Perform tevtc
on •KOa«ca
••**tc riuia
7.a
S«Oor-t «no
•v«lu«tc O«t«
O
[ Stop j
9090 - 16
Revision 0
Date September 1986
L-17
-------
-------
APPENDIX M
OBSERVATIONS AND TESTS FOR THE CONSTRUCTION QUALITY ASSURANCE
AND QUALITY CONTROL OF HAZARDOUS WASTE DISPOSAL FACILITIES
This appendix lists observations that should be made and tests that
should be performed for the construction quality assurance of the following
components of hazardous waste disposal facilities:
- Foundations.
- Embankments.
- Low-permeability soil liner.
- Leachate collection system.
Methods for testing FMLs are presented and discussed in Chapter 4. This
appendix is based on Appendix A of the EPA Technical Guidance Document,
"Construction Quality Assurance for Hazardous Waste Land Disposal Facilities"
(Northeim and Truesdale, 1986). Table M-l lists the observations and tests
by component.
REFERENCES
Anderson, D. C., J. 0. Sai, and A. Gill, 1984. Surface Impoundment Soil
Liners. Draft Report (unpublished) to U.S. Environmental Protection
Agency by K. W. Brown and Associates Inc., EPA Contract #68-03-2943.
AASHTO. 1986. Standard Specifications. American Association State Highway
and Transportation Officials. Part II Tests, 14th Edition, Washington,
D.C.:
AASHTO 217-86. "Determination of Moisture in Soils by Means of a
Calcium Carbide Gas Pressure Moisture Tester."
ASTM. Annual Book of ASTM Standards. Issued annually in several parts.
American Society for Testing and Materials, Philadelphia, PA:
C31-85. "Methods of Making and Curing Concrete Test Specimens in the
Field," Section 04.02.
M-l
-------
C138-81. "Test Method for Unit Weight, Yield, and Air Content (Gravi-
metric) of Concrete," Section 04.02.
C143-78. "Test Method for Slump of Portland Cement Concrete," Section
04.02.
C172-82. "Method of Sampling Freshly Mixed Concrete," Section 04.02.
C231-82. "Test Method for Air Content of Freshly Mixed Concrete by the
Pressure Method," Section 04.02.
0422-63(1972). "Method for Particle-Size Analysis of Soils," Section
04.08.
D559-82. "Methods for Wetting-and-Drying Tests of Compacted Soil-Cement
Mixtures," Section 04.08.
D560-82. "Methods for Freezing-and-Thawing Tests of Compacted Soil-
Cement Mixtures," Section 04.08.
D698-78. "Test Methods for Moisture-Density Relations of Soils and
Soil-Aggregate Mixtures, Using 5.5-lb (2.49-kg) Rammer and
12-in. (304.8-mm) Drop," Section 04.08.
D1556-82. "Test Method for Density of Soil in Place by the Sand-Cone
Method," Section 04.08.
D1557-78. "Test Methods for Moisture-Density Relations of Soils and
Soil-Aggregate Mixtures Using 10-1b (4.54-kg) Rammer and
18-in. (457-mm) Drop," Section 04.08.
D1633-84. "Test Method for Compressive Strength of Molded Soil-Cement
Cylinders," Section 04.08.
02165-78(1983). "Test Method for pH of Aqueous Extracts of Wool and
Similar Animal Fibers," Section 07.02.
D2166-85. "Test Method for Unconfined Compressive Strength of Cohesive
Soil," Section 04.08.
D2216-80. "Method for Laboratory Determination of Water (Moisture)
Content of Soil, Rock, and Soil-Aggregate Mixtures," Section
04.08.
D2487-85. "Classification of Soils for Engineering Purposes,"
Section 04.08.
D2488-84. "Practice for Description and Identification of Soils
(Visual-Manual Procedure)," Section 04.08.
02573-72(1978). "Method for Field Vane Shear Test in Cohesive Soil,"
Section 04.08.
M-2
-------
D2850-82. "Test Method for Unconsolidated, Undrained Strength of
Cohesive Soils in Triaxial Compression," Section 04.08.
D2922-81. "Test Methods for Density of Soil and Soil-Aggregate in Place
by Nuclear Methods (Shallow Depth)," Section 04.08.
D2937-83. "Test Method for Density of Soil in Place by the Drive-
Cylinder Method," Section 04.08.
D3017-78. "Test Method for Moisture Content of Soil and Soil-Aggregate
in Place by Nuclear Methods (Shallow Depth)," Section 04.08.
D3441-79. "Method for Deep, Quasi-Static, Cone and Friction-Cone
Penetration Tests of Soil," Section 04.08.
D4318-84. "Test Method for Liquid Limit, Plastic Limit, and Plasticity
Index of Soils," Section 04.08.
Chamberlin, E. J. 1981. Comparative Evaluation of Frost—Susceptibility
Tests. Transportation Research Record 809. U.S. Department of Trans-
portation, Washington, D.C.
Daniel, D. E., S. J. Trautwen, S. S. Boynton, and D. E. Foreman. 1984.
Permeability Testing with Flexible-Wall Permeameters. Geotechnical
Testing Journal 7(3):113-122.
Daniel, D. E., D. C. Anderson, and S. S. Boynton. 1985. Fixed-Wall Versus
Flexible-Wall Permeameters. In: Hydraulic Barriers in Soil and Rock.
A. I. Johnson, R. K. Frobel, N. J. Cavalli, and C. B. Pettersson, eds.
ASTM STP 874. American Society for Testing and Materials, Philadephia,
PA. pp 107-23.
Day, S. D., and D. E. Daniel. 1985. Field Permeability Test for Clay
Liners. In: Hydraulic Barriers in Soil and Rock. A. I. Johnson, R. K.
Frobel, N. J. Cavalli, and C. B. Pettersson, eds. ASTM STP 874.
American Society for Testing and Materials, Philadephia, PA. pp 276-87.
EPA. 1986. Test Methods for Evaluating Solid Waste. Vol 1A: Laboratory
Manual, Physical Chemical Methods. 3rd ed. SW-846. U.S. Environmental
Protection Agency, Washington, D.C.
Holtz, W. G. 1965. Volume Change. In: Methods of Soil Analysis. Part 1.
C. E. Black, ed. American Society of Agronomy, Madison, WI.
Horslev, M. J. 1943. Pocket-Size Piston Samplers and Compression Test
Apparatus. USAE Waterways Experiment Station. Vicksburg, MS.
Horz, R. C. 1984. Geotextiles for Drainage and Erosion Control at Hazardous
Waste Landfills (draft). Prepared by the U.S. Waterways Experiment
Station, Vicksburg, MS, for U.S. Environmental Protection Agency.
Interagency Agreement No. AD-96-F-1-400-1.
M-3
-------
Lanz, L. J. 1968. Dimensional Analysis Comparison of Measurements Obtained
in Clay with Torsional Shear Instruments. Master of Science Thesis,
Mississippi State University, Starkville, MS.
Northeim, C. M., and R. S. Truesdale. 1986. Technical Guidance Document:
Construction Quality Assurance for Hazardous Waste Land Disposal Facil-
ities. EPA 530-SW-86-031. OSWER Policy Directive No. 9472.003. U.S.
Environmental Protection Agency, Washington, D.C. 88 pp.
Spigolon, S. J., and M. F. Kelley. 1984. Geotechnical Assurance of Con-
struction of Disposal Facilities. Interagency Agreement No. AD-96-F-2-
A077. EPA 600/2-84-040. NT1S PB 84-155225. U.S. Environmental
Protection Agency, Cincinnati, OH.
U.S. Army. 1971. Materials Testing. TM-5-530, Washington, D.C.
U.S. Army. 1977. Construction Control for Earth and Rockfill Dams. EM
1110-2-1911. Washington, D.C.
M-4
-------
Facility component
TABLE M-l. OBSERVATIONS AND TESTS FOR THE CONSTRUCTION QUALITY ASSURANCE
AND QUALITY CONTROL OF HAZARDOUS WASTE DISPOSAL FACILITIES
Test
method reference
Factors to be inspected
Inspection methods
Foundation
Removal of unsuitable materials
Proof rolling of subgrade
Filling of fissures or voids
Compaction of soil backfill
Surface finishing/compaction
Sterilization
Slope
Depth of excavation
Seepage
Soil type (index properties)
Cohesive soil consistency
(field)
Observation
Observation
Observation
(See low-permeability soil
liner component)
Observation
Supplier's certification and
observation
Surveying
Surveying
Observation
Visual-manual procedure
Particle-size analysis
Atterberg limits
Soil classification
Penetration tests
Field vane shear test
Hand penetrometer
Handheld torvane
Field expedient unconfined
compression
NA
NA
NA
NA
NA
NA
NA
NA
ASTM D2488
ASTM D422
ASTM D4318
ASTM D2487
ASTM D3441
ASTM D2573
Horslev, 1943
Lanz, 1968
TM 5-530 (U.S.
of Army, 1971)
continued
-------
TABLE M-l (CONTINUED)
Facility component
Factors to be inspected
Inspection methods
Test
method reference
Embankments
Low-permeability
soil liner
Strength (laboratory)
Dike slopes
Dike dimensions
Compacted soil
Drainage system
Erosion control measures
Coverage
Thickness
Clod size
Tying together of lifts
Slope
Installation of protective cover
Soil type (index properties)
Unconfined compressive
strength
Triaxial compression
Surveying
Surveying; observations
(See foundation component)
(See leachate collection
system component)
(See cover system component)
Observation
Surveying; measurement
Observation
Observation
Surveying
Observation
Visual-manual procedure
Particle-size analysis
Atterberg limits
Soil classification
ASTM D2166
ASTM D2850
NA
NA
NA
NA
NA
NA
• • •
NA
ASTM D2488
ASTM D422
ASTM D4318
ASTM D2487
continued .
-------
TABLE M-l (CONTINUED)
Facility component
Factors to be inspected
Inspection methods
Test
method reference
Moisture content
In-place density
Moisture-density relations
Strength (laboratory)
Cohesive soil consistency
(field)
Permeability (laboratory)
Oven-dry method
Nuclear method
Calcium carbide (speedy)
Frying pan (alcohol or
gas burner)
Nuclear methods
Sand cone
Rubber balloon
Drive cylinder
Standard proctor
Modified proctor
Unconfined compressive
strength
Triaxial compression
Unconfined compressive
strength for soil cement
Penetration tests
Field vane shear test
Hand penetrometer
Handheld torvane
Field expedient unconfined
compression
Flexible wall
ASTM D2166
ASTM D3017
AASHTO T217
Spigolon & Kelley,
1984
ASTM D2922
ASTM D1556
ASTM D2167
ASTM D2937
ASTM D698
ASTM D1557
ASTM D2166
ASTM D2850
ASTM D1633
ASTM D3441
ASTM D2573
Horslev, 1943
Lanz, 1968
TM 5-530 (U.S.
Dept. of Army,
1971)
Daniel et al, 1984
Daniel et al, 1985
SW-846, Method
9100 (EPA, 1986)
Continued
-------
TABLE M-l (CONTINUED)
Facility component
Factors to be inspected
Inspection methods
Test
method reference
Permeability (field)
Susceptibility to frost
damage
Volume change
2 Leachate collec-
oo tion system:
- Granular drain-
age and fil-
ter layers
Thickness
Coverage
Soil type
Density
Permeability
(laboratory)
Large diameter single-
ring infiltrometer
Sai-Anderson infiltrometer
Susceptibility classifi-
cation
Soil-cement freeze-thaw test
Consolidometer (undisturbed
or remolded sample)
Soil-cement wet-dry test
Soil-cement freeze-thaw test
Surveying; measurement
Observation
Visual-manual procedure
Particle-size analysis
Soil classification
Nuclear methods
Sand cone
Rubber balloon
Constant head
Day and Daniel,
1985
Anderson et al,
1984
Chamberlin, 1981
ASTM D560
Holtz, 1965
ASTM D559
ASTM D560
NA
NA
ASTM D2488
ASTM D422
ASTM D2487
ASTM D2922
ASTM D1556
ASTM D2167
ASTM D2434
continued
-------
TABLE M-l (CONTINUED)
Facility component
Factors to be inspected
Inspection methods
Test
method reference
- Synthetic
drainage
and filter
layers
- Pipes
Material type
Handling and storage
Coverage
Overlap
Temporary anchoring
Folds and wrinkles
Geotextile properties
Material type
Handling and storage
Manufacturer's certifi-
cation
Observation
Observation
Observation
Observation
Observation
Tensile strength
Puncture or burst
resistance
Tear resistance
Flexibility
Outdoor weatherability
Short-term chemical
resistance
Fabric permeability
Percent open area
Manufacturer's certification
Observation
NA
NA
NA
NA
NA
NA
Horz, 1984
Horz, 1984
Horz, 1984
Horz, 1984
Horz, 1984
Horz, 1984
Horz, 1984
Horz, 1984
NA
NA
continued . .
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TABLE M-l (CONTINUED)
Facility component
Factors to be inspected
Inspection methods
Test
method reference
Cast-in-place con-
crete structures
Electrical and
mechanical
equipment
Location
Layout
Orientation of perforations
Sampling
Consistency
Compressive strength
Ai r content
Unit weight, yield, and
air content
Form work inspection
Equipment type
Material type
Operation
Electrical connections
Insulation
Grounding
Surveying
Surveying
Observation
Sampling fresh concrete
Slump of portland cement
Making, curing, and testing
concrete specimens
Pressure method
Gravimetric method
Observation
Manufacturer's certification
Manufacturer's certification
As per manufacturer's
instructions
As per manufacturer's
instructions
As per manufacturer's
instructions
As per manufacturer's
instructions
NA
NA
NA
ASTM C172
ASTM C143
ASTM C31
ASTM C231
ASTM C138
NA
NA
NA
NA
NA
NA
NA
Source: Northeim and Truesdale, 1986, pp 83-5
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APPENDIX N
LOCUS-OF-BREAK CODES FOR VARIOUS TYPES OF FML SEAMS
This appendix presents locus-of-break codes for various types of FML
seams. These codes can be used in reporting the results of CQA destructive
seam testing. They have been found to be particularly useful in cases where
the type of break is important for determining whether or not the tested seam
meets specification, e.g. for determing whether or not there was a film-
tearing bond when the tested specimens broke. These codes can be included in
specifications for defining specific types of breaks that meet specification
and for defining types of breaks that are not considered to reflect the
quality of the seam, i.e. "no test" situations.
-Dielectric-welded or solvent-welded seams in unreinforced FMLs.
- Seams in three-ply fabric-reinforced FMLs.
- Fillet-extrusion weld seams in semicrystalline FMLs.
- Extrusion weld seams in semicrystalline FMLs.
- Dual-hot-wedge seams in semicrystalline FMLs.
N-l
-------
Schematic of
Untested Specimen
Direction
of Peel
^
Weld
Top Sheet
V
x Bottom Sheet
Types of Breaks
Locus-of-Break
Code
Break
Description
Classification3
Clamp
CL
BRK
V
SE
Break in sheeting
at clamp edge.
Break in sheeting.
FTB
Break at seam edge.
FTB
V
Break in sheeting
AD-BRK after some adhesion
failure between the
sheets.
AD
Failure in adhesion
between the sheets.
Non-FTB
FTB = Film - Tear Bond.
"Acceptance of CL - type breaks may depend on whether test values meet
a minimum specification value. In general, though, a CL - type break should
be considered a "no test". If specimens for a particular sample break con-
sistently at the clamp edge, changes in the testing procedure should be
considered, e.g. changing the clamp face, using a dumbell - type specimen.
Figure N-l. Locus-of-break codes for dielectric-welded or solvent-welded
seams in unreinforced FMLs tested for seam strength in shear and
peel modes.
N-2
-------
Schematic of a Seam of a 3-Ply
Fabric-Reinforced FML
Direction
of Peel
Fabric
Plies of
Polymer
Locus-of-Break
Code
Break
Description
Classification3
AD
Adhesion failure resulting in
delamination in the plane of
the bond.
Non-FTB
Delamination in the plane
DEL of the scrim. (Applicable
to peel only).
FTB
Delamination in the plane
of the scrim aftdr Some
AD-DEL delamination in the plane
of the bond. (Applicable
to peel only)
FTB
Break in the sheet through
both the fabric and the plies
of polymer. Fabric break may
precede break in sheeting.
FTB
FP
Fabric pullout. Pullout of the
threads parallel to the direction
of test followed by break in the
plies of polymeric sheeting.
No Test
' FTB = Film - Tear Bond.
Figure N-2. Locus-of-break codes for seams in three-ply fabric-reinforced
FMLs tested for seam strength in shear and peel modes.
N-3
-------
Schematic of
Untested Specimen
Bead Outer Area
^_j2flfrt f / Buffed Area
— Hot Tack (delaminated)
Types of Breaks
,^*%_
Locus-of-Break
Code
AD1
Break
Description
Failure in adhesion. Specimens
may also delaminate under the
Classification3
Non-FTB
AD2
AD-WLD
aFTB= Film-Tear Bond.
SE1
SE2
SE3
BRK1
BRK2
AD-BRK
HT
bead and break through the thin
extruded material in the outer area.
Failure in adhesion.
Break through the fillet. Breaks
through the fillet range from
breaks starting at the edge of
the top sheet to breaks through
the fillet after some adhesion
failure between the fillet and
the bottom sheet.
Break at seam edge in the bottom
sheet. Specimens may break any-
where from the bead/outer area
edge to the outer area/buffed area
edge. (Applicable to shear only).
Break at seam edge in the top
sheet. Specimens may break any-
where from bead/outer area edge
to the outer area/buffed area
edge.
Break at seam edge in the bottom
sheet. (Applicable to peel only)
Break in the bottom sheeting. A
"B" in parentheses following the
code means the specimen broke
in the buffed area. (Applicable
to shear only).
Break in the top sheeting A
"B" in parentheses following
the code means the specimen
broke in the buffed area
Break in the bottom sheeting
after some adhesion failure
between the fillet and the bottom
sheet (Applicable to peel only)
Break at the edge of the
hot tack for specimens which
could not be delaminated in
the hot tack
Non-FTB
Non-FTB D
FTB
FTB
FTB
FTB
FTB
FTB
No Test
Acceptance of AD-WLD breaks may depend on whether test values
meet a minimum specification value and not on classification as a
FTB or non-FTB break
Figure N-3. Locus-of-break codes for fillet-extrusion weld seams in semi-
crystalline FMLs tested for seam strength in shear and peel
modes.
N-4
-------
Schematic of
Untested Specimen
Top Sheet
Extrudate
Direction of Peel
Bottom Sheet
Location of Break
Locus-of-Break Break
Code Description
Classification3
BRK
Break in sheeting
outside weld area.
Break can be in
either the top or
bottom sheet
FTB
Break in top sheet
at seam edge.
FTB
SE2
Break in bottom
sheeting at seam
FTB
^>
SE3
Break in bottom
sheeting at seam
edge. (Applicable
to peel only).
FTB
AD-BRK
Break in sheeting
after some adhesion
failure between ex-
trudate and surface
of the sheeting.
Break can be in
either the top or
bottom sheet.
FTB
AD
Failure in adhesion
between the ex-
trudate and the
sheeting surface.
Non-FTB
a FTB - Film - Tear Bond
Figure N-4. Locus-of-break codes for extrusion weld seams in semi crystal line
FMLs tested for seam strength in shear and peel modes.
N-5
-------
Schematic of
Untested Specimen
Weld B Weld A
Top Sheet
' Bottom Sheet
Direction of Initial Peel
Types of Break
Locus-of-Break Break
Code Description Classification3
AD
Adhesion failure.
Non-FTB
I EZ3
BRK
SE1
Break in sheeting. Break
can be in either top or
bottom sheet.
Break at outer edge of
seam. Break can be
in either top or bottom
sheet.
FTB
FTB
Break at inner edge of
SE2 seam through both
sheets.
FTB
Break in first seam
after some adhesion
AD-BRK failure. Break can be
in either the top or
bottom sheet.
FTB
a FTB = Film - Tear Bond
NOT TO SCALE
Figure N-5. Locus-of-break codes for dual hot-wedge seams in semi crystal line
FMLs tested for seam strength in shear and peel modes. In cases
where the Weld A fails in adhesion in a peel test, it is recom-
mended that the test be stopped, that the specimen be replaced
in the testing machine, and that Weld B be tested by peeling in
the direction opposite to that used to Weld A.
N-6
*U.S. GOVERNMENT PRINTING OFFICE:1988-548-15B 187024
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