4
v>EPA
Washington. DC 20460
OSWER Directive Initiation Request
\r\\ii\n\
Originator Information
Name of Contact Person
Paul Cassidy
Mad Code
WH-565E
Telephone Number
382-4^2
Lead Office
LJ OERR
G3 OSW
D OUST
CD OWPE
CD AA-OSWER
Approved for Review
Signature of Office Director
Date
Title
Lining of Waste Impoundment and Disposal Facilities
f
O
Summary of Directive
This document supports RCRA Guidance Documents by describing current technologies and
methods for designing hazardous waste facilities or for evaluating the performance of'
a facility design; the information and guidance presented in this manual constitute a
suggested approach for good engineering practices.
Jlhis report describes and details the major aspects of liners for hazardous waste
^•disposal facilities. Various procedures are presented as to the selection, manufacture,
Piconstruetion, and use of the major types of liners to minimize the possibility of
jadverse environmental impact.
Keywords:. Hazardous Waste; Liners; Selection, Manufacturing,»nd Design of Liners
Type of Directive (Manual. Policy Directive. Announcement, etc.I
Technical Resource Document
Status
D Draft
ED Final
LJ New
I—I Revision
Does this Directive Supersede Previous Directives;' | | Yes [73 No Does It Supplement Previous Directiveisi? [ 1 Yes LTj No
if "Yes" to Either Question, What Directive (number, title)
Review Plan
CD AA-OSWER D OUST
CD OERR CD OWPE
OSW LJ Regions
^ffgr
D OECM
D OGC
D OPPE
I2S Other (Specify!
ORD and experts in the hazardous waste field
S Request Meets OSWER Directives System Format
grature of Lead Office Directives Officer
• Date
Signature of OSWER Directives Officer
• Date
EPA Form 1 31 5-1 7 (1 0-851
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r.itsc: Sates
Environmental Protection
Agency
0"'C9 at Soiia Waste
arc! Emergency Resoonse
Wasnmgton DC 2046.0
3W-37C
Marcn 1983
Revised Edition
Lining of
Waste Impoundment and
Disposal Facilities
r.
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LINING OF WASTE IMPOUNDMENT
AND DISPOSAL FACILITIES
Project Officer
Robert Landreth
Solid and Hazardous Waste Research Division
Municipal Environmental Research Laboratory
Cincinnati, Ohio 45268
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
. OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
For uJe bf toe Superintendent of Documents, U.9. Oorerameat Printing Office Waihlnmon. D.C. 20402
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4
DISCLAIMER
This report has been reviewed by the Municipal Envi ronmental Research
Laboratory, U.S. Environmental Protection Agency, and approved for publica-
tion.Approval does not signify that the contents necessarily reflect the
views and policies of the U.S. Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement or
recommendation for use.
11
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FOREVJORD
The Environmental Protection Agency was created because of increasing
public and governmental concern about the dangers of pollution to the
health and welfare of the American people. Noxious air, foul water, and
spoiled land are tragic testimony to the deterioration of our natural
environment. The complexity of that environment and the interplay of its
components require a concentrated and integrated attack on the problem.
Research and development is the first necessary step in problem solu-
tion-, it involves defining the problem, measuring its impact, and searching
for solutions. The Municipal Environmental Research Laboratory develops
new and improved technology and systems to prevent, treat, and manage
wastewater and solid and hazardous waste pollutant discharges from municipal
and community sources; to preserve and treat public drinking water supplies;
and to minimize the adverse economic, social, health, and aesthetic effects
of pollution. This publication is one of the products of that research --
a vital communications link between the researcher and the user community.
This report describes and details the major aspects of liners for
hazardous waste disposal facilities. Various procedures are presented as
to the selection, manufacture, construction, and use of the major types of
liners to minimize the possbility of adverse environmental impacts.
Francis T. Mayo
Director, Municipal
Research Laboratory
Environmental
•m
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PREFACE
Subtitle C of the Resource Conservation and Recovery Act (RCRA) requires
the 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 is published in
40 Code of Federal Regulations (CFR) 260 through 265 and 122 through 124.
Parts 264 and 265 of 40 CFR contain standards applicable to owners and
operators of all facilities that treat, store, or dispose of hazardous wastes.
Wastes are identified or listed as hazardous under 40 CFR Part 261. The Part
264 standards are implemented through permits issued by authorized States or
the EPA in accordance with 40 CFR Part 122 and Part 124 regulations. Land
treatment, storage, and disposal (USD) regulations in 40 CFR Part 264 issued
on July 26, 1982, establish performance standards for hazardous waste landfills,
surface impoundments, land treatment units, and waste piles.
The Environmental Protection Agency is developing three types of documents
for preparers and reviewers of permit applications for hazardous waste USD
facilities. These types include RCRA Technical Guidance Documents, Permit
Guidance Manuals, and Technical Resource Documents (TRDs). The RCRA Technical
Guidance Documents present design and operating specifications or design evalua-
tion 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 the information requirements.
These manuals will include a discussion of each step in the permitting process,
and a description of each set of specifications that ^ust be considered for
inclusion in the permit.
The Technical Resource Documents present state-of-the-art summaries of
technologies and evaluation techniques determined by the Agency to constitute
good engineering designs, practices, and procedures. They support the RCRA
Technical Guidance Documents and Permit Guidance Manuals in certain areas
(i«e-» liners, leachate management, closure, covers, water balance) by describ-
ing current technologies and methods for designing hazardous waste facilities
or for evaluating the performance of a facility design. Although emphasis is
given to hazardous .waste facilities, the information presented in these TRDs
may be used in designing and operating non-hazardous waste USD facilities as
well. Whereas the RCRA Technical Guidance Documents and Permit Guidance Manuals
are directly related to the regulations, the information in these TROs covers
a broader perspective and should not be used to interpret the requirements of
the regulations.
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A previous version of this document dated September 1980 was announced in
the Federal Register for public comment on December 17, 1980. The new edition
incorporates "changes" as a resu"t of the public comments, and supersedes the
September 1980 version. Commeius 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 (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 Impoundment and Disposal Facilities,"
SW-870).
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Abstract
Lining waste storage and disposal units Is a primary method to control
the release of liquid and gaseous waste components Into adjacent areas. This
manual provides current technological information about a variety of liner
materials that may be used to contain hazardous wastes. Guidance is given to
assist in the selection, installation, and maintenance of appropriate liners
for specific types of wastes in particular storage or disposal units. Several
test methods for determining waste: liner compatibility are included, and a
case study analysis methodology for lined units is presented. Liner manufactur-
ers and material sources are listed.
vii
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TABLE OF CONTENTS
Page
FOREWORD i i i
PREFACE v
ABSTRACT vi *
LIST of FIGURES xix
LIST of TABLES xxiv
ACKNOWLEDGMENTS xxx
CHAPTER 1. INTRODUCTION 1
CHAPTER 2. CHARACTERISTICS OF WASTES AND WASTE FLUIDS 4
2.1 Introduction 4
2.2 Classification and General Characteristics of Waste Liquids
and Leachates 5
2.3 Liquids Generated by Waste 6
2.3.1 Liquids in Waste Leachate 7
2.3.2 Dissolved Components in Waste Leachate 9
2.4 Municipal Solid Waste (MSW) ' 9
•2.4.1 Description of the Waste 9
' 2.4.2 Characteristics of Leachate from Municipal Solid Waste 11
2.4.3 Potential Pollution by MSW Leachate 11
2.4.4 Potential Effects of MSW Leachate Upon Liners 16
2.4.5 Gas Production in MSW 16
2.5 Hazardous and Toxic Wastes by Industry 16
2.5.1 Electroplating and Metals Finishing Industry 16
2.5.2 Inorganic Chemicals Industry 20
2.5.3 Metal Smelting and Refining Industry 22
2.5.4 Organic Chemicals Industry 23
2.5.5 Paint and Coatings Formulating Industries 23
'2.5.6 Pesticide Industry 25
2.5.7 Petroleum Refining Industry 26
2.5.8 Pharmaceutical Industry 26
2.5.9 Pulp and Paper Industry 29
2.5.10 Rubber and Plastics Industry * 30
2.5.11 Soap and Detergent Industry 31
ix,
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Page
2.6 Other Nonradioactive and Special Wastes 31
2.6.1 Coal-Fired Electric Power Industry 31
2.6.1.1 High-volume wastes 32
2.6.1.2 Low-volume wastes 35
2.6.2 Mining and Refining Industries 35
References 41
CHAPTER 3. LINING MATERIALS AND LINING TECHNOLOGY 45
3.1 Introduction 45
3.2 Soils and Clays 47
3.2.1 Introduction 47
3.2.2 Clay Properties 48
3.2.2.1 Chemistry and mineralogy of clays 48
3.2.2.2 Attentuation properties of soil liners 51
3.2.3 Engineering Characteristics of Soils and Clays 53
3.2.3.1 Atterberg limits 53
3.2.3.2 Compactibility 55
3.2.3.3 Volume changes ' 57
3.2.3.4 Permeability 59
3.3 Admixed Lining Materials 65
3.3,1 Introduction 65
3.3.2 Hydraulic Asphalt Concrete (HAC) 65
3.3.3 Soil Cement 67
3.3.4 Soil Asphalt 67
3.3.5 Bentonite-Soil Mixtures 67
3.3.5.1 Types of bentonite 67
3.3.5.2 Methods for evaluating bentonite mixtures 71
3.4 Flexible Polymeric Membranes 71
3.4.1 Introduction 71
3.4.2 Description of the Polymeric Liner Industry 72
3.4.2.1 Raw materials production" 72
3.4.2.2 Preparation of liner compounds and manu-
facture of sheeting 72
3,4.2.3 Fabrication • 75
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3.4.2.4 Installation 75
3.4.2.5 Engineering and design services 75
3.4.3 Polymers Used In Liner Manufacture 75
3.4.3,1 Butyl rubber 77
3.4.3.2 Chlorinated polyethylene 77
3.4.3.3 Chlorosulfonated polyethylene (CSPE) 78
3.4.3.4 Elasticized polyolefins 79
3,4.3.5 Epichlorohydrin rubbers (CO and ECO) 79
3.4.3.6 Ethylene propylene rubber (EPDM) 79
3.4.3.7 Neoprene 80
3.4.3.8 Nitrile rubber 80
3.4.3.9 Polyethylene 81
3.4.3.10 Polyvinyl chloride 81
3.4.3.11 Thermoplastic elastomers (TPE) 82
3.4.4 Membrane Manufacture 83
3.4.5 Testing of Flexible Polymeric Membranes • 84
3.4.5.1 Introduction 84
3.4.5.2 Analytical properties of polymeric
membrane liners 88
3.4.5.3 Physical properties of polymeric membrane
liners 91
3.4.5.4 Tests of membranes under environmental stress 94
3.4.5.5 Testi.ng of seam strength of factory and
field systems • 95
3.4.5.6 Compatibility and durability tests 96
3.4.6 Se'aming of Polymeric Liner Membranes 96
3.4.6.1 Introduction 96
3.4.6.2 Solvent -"welding" 97
3.4.6.3 Bodied solvents 97
3.4.6.4 Solvent cements and contact cements 99
3.4.6.5 Vulcanizing adhesives 99
3.4.6.6 Tapes 100
3.4.6.7 Thermal techniques • 100
3,4.6.8 Welding or fusion methods 100
3.5 Sprayed-on Linings 100
3.5.1 Introduction 100
3,5.2 Air-blown Asphalt 101
3.5.3 Membranes of Emulsified Asphalt- 102
3.5.4 Urethane-Modified Asphalt 103
3.5.5 Rubber and Plastic Latexes 103
3.6 Soil Sealants 103
xi
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Page
3.7 Chemical Absorptive Liners 105
References 107
CHAPTER 4. LINING MATERIALS IN SERVICE-TYPE ENVIRONMENTS 114
4.1 Introduction 114
4.2 The Effects of Waste Liquids on Clay Soils 115
4.2.1 Introduction . 115
4.2.2 Failure Mechanisms in Clay-Soil Liners 116
4.2.2.1 Increase in permeability throughout the
soil liner due to volume changes 116
4.2.2.2 Dissolution of clay ' 120
4.2.2.3 Piping 121
4.2.2.4 Slope stability 123
4.2.2.5 Miscellaneous • 124
4.2.3 Laboratory Study of the Effects of Different
Organic Liquids on Soil Permeability 125
4.2.3.1 Introduction 125
4.2.3.2 Materials, and methods 126
4.2.3.3 Experimental results 127
4.2.4 Effect of Inorganics on Soil Permeability 141
4.3 Effects of Waste Liquids on Flexible Polymer Membrane Liners 142
4.3.1 Introduction 142
4.3.2 Exposure of Membrane Liners to MSW Leachate 143
4.3.2.1 Experimental details 143
4.3.3 Laboratory Results of Exposure to MSW Leachate 146
4.3.4 Field Verification of Membrane Liner Performance 152
4.3.4.1 PVC liner in small demonstration landfill 157
4.3.4.2 PVC liner in sludge lagoon 158
4.3.4.3 Boone County field site 159
4.3.4.4 Unsupported CSPE membrane liner 162
4.3.5 Exposure of Membrane Liners to Hazardous Wastes 162
4.3.5.1 Exposure of primary liner specimens 164
4.3.5.2 Immersion tests 169
4.3.5.3 Pouch test. 169
4.3.5.4 Tub test " 172
4.3.6 The Effects of Low Concentrations of Organic
Constituents in Wastes . . 174
xii
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Page
4.3.7 General Discussion of Results 175
4.4 Effect of Waste Fluids on Admix and Other Liner Materials 179
4.4.1 Exposure to Municipal Solid Waste Leachate 179
4.4.2 Exposure to Hazardous Wastes 179
4.5 Compatibility of Liner Materials in Waste Fluids 182
4.5.1 Introduction 182
4.5.2 Screening of Liner Materials Based upon State-
of-the-Art Know!edge 182
\
4.5.2.1 Characterizing the waste 182
4.5.2.2 Characterizing the liner materials available 183
4.5.2.3 Matrix of liner materials-waste
compatibilities 183
4.5.3 Testing of Specific Combinations of Liners and Wastes 185
4.5.3.1 Sampling and analyses of^wastes for
compatibility tests 185
4.5.3.2 Compatibility testing of soils 185
4.5.3.3 Polymeric materials 185
4.6 Failure Mechanisms and Estimating Service Lives 186
4.6.1 Physical Failures 187
4.6.1.1 Puncture 188
4.6.1.2 Tear 188
4.6.1.3 Creep 188
4.6.1.4 Freeze-thaw cracking 188
4.6.1.5 Wet-dry cracking 188
4.6.1.6 Differential settling 188
4.6.1.7 Thermal stress 189
4.6.1.8 Hydrostatic pressure 189
4.6.1.9 Abrasion 189
4.6.2 Biological Failures . 189
4.6.3 Chemical Failures ' 189
4.6.3.1 Swelling 190
4.6.3.2 Extraction 190
4.6.3.3 Outdoor exposure 190
References 191
CHAPTER 5. DESIGN AND CONSTRUCTION OF LINED WASTE FACILITIES 202
202
5.1 Introduction
xiii
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5.1.1 Types of Constructed Impoundments 203
5.1.2 Site Planning Considerations 205
5.2 Disposal Facilities With Liners of Soils and Clays 205
5.2.1 General Discussion 206
5.2.2 Testing of Soil for Selection and Design of Liner 209
5.2.2.1 Atterberg limits . 209
5.2.2.2 Determination of moisture-density
relationships 210
5.2.2.3 Permeability to water 210
5.2.2.4 Permeability to waste liquids 212
5.2.2.5 Determination of soil strength
characteristics 212
5.2.3 Designing of Soi" and Clay Liners 216
5.2.4 Excavation and Embankment Construction 219
5.2.4.1 Excavation and sidewall 219
5.2.4.2 Drainage and leak detection/control systems 223
5.2.4.3 Monitoring wel Is 225
5.2.4.4 Field compaction of soil for construction
of lined waste disposal facilities 225
5.2.5 Quality Control in Preparation.of a Clay Soil Liner 228
5.3 Construction of Linings of Admixed Materials 234
5.3.1 Introduction • 234
5.3.2 Soil Cement 234
5.3.3 Concrete and Cement 234
5.3.4 Asphalt Concrete 236
5.3.5 Construction of Bentonite-Clay Liners 238
5.4 Design and Construction of Flexible Membrane Liner
Installations 238
5.4.1 Introduction 238
5.4.2 Planning and Design Considerations for Membrane Liners 240
5.4.2.1 Type and texture of "In situ" soils 241
5.4.2.2 Subgrade characteristics ' 241
5.4.2.3 Desired characteristics of bottom and side
surfaces 242
' 5.4.2.4 Location of bedrock - • 242
. 5.4.2.5 Stability of materials 242
5.4.2.6 Drainage consideration 242
5.4.2.7 Impoundment dimensions 243
xiy
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5.4.2.8 Wind direction and velocity
5.4.2.9 Ambient temperature
5.4.2.10 Local vegetation
5.4.2.11 Floor consideration
5.4.2.12 Berm width requirements
5.4.2.13 Inflow/outflow/overflow conveyances
. 5.4.2.14 Monitoring and leak detection systems
5.4.2.15 Monitoring liner performance
5.4.3 Preparation of Subgrade for Flexible Membrane Liners
5.4.3.1 Compaction of subgrade
5.4.3.2 Fine finishing of surface
5.4.4 Liner Placement
5.4.5 Quality Control in Construction of Liner Systems
5.4,5.1 Subgrade
5.4.5.2 Flexible polymeric membrane liner
5.4.5.3 Penetrations
5.4.6 Earth Covers for Flexible Membrane Liners
5.4.7 Use of Coupons to Monitor the Liner During Service
5.4.8 Gas Venting
5.5 Placement of Miscellaneous Types of Liners
5.5.1 Sprayed-on Liners
5.5.2 Placement of Soil Sealants
5.5.3 Placement of Chemisorptive Liners
5.6 Liners and Leachate Management for Solid Waste Landfills
5.6.1 Environment of the Liner in a Sanitary Landfill
5.6.2 Estimating Leachate Volume
5.6.3 Transmissivity of Leachate
5.6.4 Leachate Collection System Network
5.6.5 Leachate Withdrawal and Monitoring Facilities
5.6.5.1 Spacing and capacity of sumps
5.6.5.2 Monitoring and withdrawal
5.6.6 Covers and Closure of Lined Waste Impoundments
References
Chapter 6. MANAGEMENT, OPERATIONS, AND MAINTENANCE OF LINED WASTE
DISPOSAL FACILITIES - •-.
6.1 Introduction
243
243
243
244
244
244
244
245
245
245
246
250
250
251
252
253
253
257
257
259
259
262
262
262
262
264
268
271
274
274
275
276
278
283
283
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Page
6.2 Standard Operating Procedures for a Waste Disposal Facility 283
6.3 Information on Design, Construction, and Materials of
Construction 284
. 6.4 Control of Incoming Waste 284
6.5 Monitoring the Performance of the Impoundment 285
6.6 Monitoring the Liner 285
6.7 Condition of Earthwork 286
6.7.1 Vegetation Control 286
6.7.2 Rodent Control 286
6.8 Inspection of Appurtenances 286
6.9 General Comments 286
6.10 Unacceptable Practices 286
References 288
CHAPTER 7. COSTS OF LINING MATERIALS FOR WASTE DISPOSAL FACILITIES 289
7.1 General Factors Contributing to the Costs of Linings 289
7.2 Polymeric Membrane Liners 290
7.3 Soil, Admix and Sprayed-on Liners . 291
7.4 Case Study Methodology for Analyzing Cost 291
CHAPTER 8. SELECTION OF A LINER MATERIAL FOR A WASTE DISPOSAL FACILITY 294
8.1 Introduction 294
8.2 The Function of the Waste Disposal Facility 295
8.3 Clay Soil on Site 295
8.4 Hydrology 295
8.5 Significant Environmental Factors 295
8.6 Acceptable Flow Through a Liner ... .. 296
8.7 Review of Available Materials . 296
8.8 Cost of Liner Materials 296
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8.9 Compatibility Tests 296
8.10 Selection of Liner Material 296
CHAPTER 9. SPECIFICATIONS FOR CONSTRUCTION OF LINED WASTE IMPOUNDMENTS 298
9.1 Introduction 298
9.2 Specifications for Construction 298
9.3 Specifications for Liner Materials 300
9.3.1 Current ASTM Specifications 300
9.3.2 Other Specifications and Specifications Under
Development 301
9.3.3 Suggested Specifications for Representative
Current Materials 304
References 305
APPENDIX I UNIFIED SOIL CLASSIFICATION SYSTEM 307
APPENDIX II REPRESENTATIVE LIST OF ORGANIZATIONS IN LINER INDUSTRY 308
II-A Polymeric Membrane Liners 309
II-A.l Polymer producers 309
II-A.2 Manufacturers of polymeric membrane sheetings 310-
II-A.3 Fabricators of liners 312
II-A.4 Installing contractors 313
II-B Bentonite Producers and Suppliers " 315
II-C Other Liner Materials . 316
*
II-D Miscellaneous Organizations in the Liner Industry 317
APPENDIX III SELECTED LINER TEST METHODS 318
III-A Immersion Test of Membrane Liner Materials for
Compatibility with Wastes 318
III-B Tub Test of Polymeric Membrane Liners 324
III-C Test Method for the Permeability of Compacted Clay Soils
(Constant Elevated Pressure Method) 327
References 336
I II-D Volatiles Test of Unexposed Polymeric Liner Materials 338
III-E Tests for Extractable Content of Unexposed Polymeric Lining
Materials _-.... 34Q
III-F Analysis of Exposed Polymeric Lining Materials 344
xvii
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Page
APPENDIX IV INSTALLATION OF FLEXIBLE POLYMERIC MEMBRANE LINERS 345
IV.1 On-Site Storage of Materials and Equipment 345
IV.2 Installation Equipment 345
IV.3 Manpower Requirements 353
IV.4 Liner Placement 353
IV.5 Field Seaming 355
IV-6 Anchoring/Sealing Around Structures/Penetrations 366
APPENDIX V LEACHATE COLLECTION SYSTEM NETWORK 374
V.I Flow Capacity 374
V.2 Structural Stability of Pipe 377
V.2.1 Introduction 377
V.2.2 Loads Acting on Pipe 377
V.2.2.1 Trench condition 377
V.2.2.2 Positive projecting condition 380
V.2.2.3 Perforated pipe 382
V.2.3 Deflection 382
V.2.4 Buckling Capacity 385
V.2.5 Compressive Strength ' 385
V.2.6 Construction Loadings 385
V.2.7 Procedures for Selection of Pipe Strength 386
APPENDIX VI SYSTEM ANALYSIS AND OPTIMIZATION OF SOIL LINER DESIGN 389
APPENDIX VII CASE STUDY ANALYSIS METHODOLOGY 399
APPENDIX VIII SPECIFICATIONS FOR FLEXIBLE POLYMERIC MEMBRANE MATERIALS 403
GLOSSARY OF TERMS RELATING TO LINER TECHNOLOGY 414
1 Admix liner materials 415
2 Asphalt tecnnology 416
3 Chemistry 418
4 Hazardous wastes management 420
5 Hydrology 422
6 Polymeric membrane liner technology . 424
7 Site construction 430
8 Soils science and engineering 433
9 Solid waste management " " . 439
References 442
BIBLIOGRAPHY 445
xviii
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LIST OF FIGURES
Page
2-1. Sources of primary and secondary leachates generated by wastes. 7
2-2. Genralized composition of waste liquids that may contact a liner
in service, showing the components that may be present. 8
3-1. Relative permeability values for three clays. 51
3-2. Isoswell lines on moisture-density graph; expansive clays under
extremely dry and dense conditions. 60
3-3. Basic structure of the polymeric membrane liner industry. 73
3-4. Roll configuration on calenders. 84
3-5. Calender arrangement for coating sheeting. .85'
3-6. Nylon-reinforced butyl lining samples. 86
4-1. Permeability of the four clay soils to standard aqueous permeant. 129
4-2. Permeability of the four clay soils to glacial acetic acid. • 130
4-3. Permeability and breakthrough curves of the four clay soils
treated with aniline. 132
4-4. Permeability of the four clay soils to acetone. 133
4-5. Permeability of the four clay soils to methanol and the break-
through curve for the methanol-treated mixed cation illitic
clay soil. 135
4-6. Permeability of the mixed cation illitic clay soil to methanol
at two hydraulic gradients. 136
4-7. Permeability and breakthrough curves of the four clay soils
treated with xylene. .. 137
4-8. Permeability and breakthrough curves of the four clay soils
treated with heptane. 139
xlx
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Page
4-9. Permeability and breakthrough curve for the noncalcareous
smectitic clay soil. 140
4-10. Landfill simulator used to evaluate liner materials exposed to
sanitary landfill leachate. 144
4-11. Base o the landfill simulator in which the liner materials
were exposed. 145
4-12. Ranges of swelling values of membranes of different polymeric
types during immersion in leachate for 8 and 19 months. 153
4-13. Ranges of retentions of tensile strength of membranes of
different polymeric types on immersion in landfill leachate
for 8 and 19 months. 153
4-14. Retention of tensile strength of the individual polymeric
membranes as a function of immersion time in landfill leachate. 155
4-15. Exposure cells for membrane liners. 166
4-16. Exposure cell for thick lirers. 166
4-17. Schematic, representation of the movements of the mobile con-
stituents in the pouch (bag) test of membrane liner materials. 172
4-18. Types of swelling of polymeric membranes. 178
5-1. An excavated impoundment. 204
5-2. Diked pond partially excavated below grade. . 204
5-3. A cross-valley pond configuration. 205
5-4. Schematic representation of the relationships w- p ,
w-K, and p-K, Case 1. 218
5-5. Schematic representation of the relationships w- p ,
w-K, and p-K, Case 2. 220
5-6. Typical earthwork equipment used during impoundment
construction. 221
5-7. Trenching machine for ancho" trenches (top). Dozer and earth
mover for berm construction (bottom). 222
5-8. Conveyor system used during impoundment-construction. 223
5-9. Typical compaction equipment. 227
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Page
5-10. Water vehicle used to prepare the soil for compaction, 228
5-11. Steps in the installation of a soil-cement liner. 235
5-12. A two-inch thick asphalt concrete liner is applied using road
paving equipment and methods. 237
5-13. Bulk application of bentonite with an oil field bottle truck
fitted with a six-foot wide distributor. 239
5-13a. Mixing the bentonite into the soil with a large agricultural
disc. 240
5-14. Photographs showing various stages of subgrade finishing. 247
5-15. Scraper and roller being used to fine finish a subgrade, 248
5-16. Representative subgrade surface texture. 248
5-17. Salt grass penetrating a 30 mil flexible liner. . 249
5-18. Seaming of HOPE liner with a fusion welder. 253
5-19. Testing the integrity of HOPE liner seams. 254
5-20. Two photographs showing bulldozers applying a soil cover over
membrane liners. 258
5-21. Designs of two different gas vents for membrane liners. 260
5-22. Placement of sprayed-on liners. 261
5-23. Schematic drawing of a lined sanitary landfill. 263
5-24. Percolation through solid waste and movement of the leachate
into the soil environment. 268
5-25. Preclusion of leachate production through use of proper
drainage grades and cover. 269
5-26. Accumulation, containment, and collection of landfill leachate. 270
5-27. Accumulation, containment, collection and withdrawal of land-
fill leachate showing saturation levels for different
conditions. 271
5-28. Selected characteristics of soils and waste fills. 272
5-29. Determination of leachate head on impervious liners using flow
net solution. 273
xxi
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Page
5-30. Typical inclined leachate monitoring and removal system. 276
5-31. Typical vertical leachate monitoring and removal system. 277
III-A-1. Die for Goodyear dumbbell. 320
III-A-2. Suggested pattern for cutting test specimens from cross-
linked, thermoplastic, or crystalline immersed liner samples. 321
III-8-1. The open exposure tubs lined with polymer membranes and
partially filled with hazardous wastes. 325
III-C-1. Schematic of the compaction permeameter. . 328
III-C-2. Schematic of the compaction permeameter test apparatus. 328
III-D-1. Machine direction determination. 339
IV-1. Liner panels are shipped to the site on wooden pallets, either
rolled or accordion folded. 346
IV-2. Damage to a fabric reinforced liner caused by "blocking" of the
sheeting. 347
IV-3. High-density polyethylene (HOPE) is shipped to the site rolled
onto drums. 348
IV-4.- Special equipment for seaming of high-density polyethylene
(HOPE). 349
IV-5. This crew is using a board for support under the area being
seamed. 350
IV-6. Sandbags are often used to anchor unseamed sheets of liner
and unseamed edges to prevent wind damage. 351
IV-7. Heat guns are used to facilitate field seaming. 352
IV-8. The panels of liner membrane are unfolded or unrolled. 356
IV-9. Workmen "pull" the panel across the subgrade. 357
IV-10. Once a panel has been unfolded, the crew "spots" or positions
it in the proper location. 358
IV-11. The instructions for unrolling liner panels are clearly
shown on each container. -• - • ...... 359
IV-12. Each panel must be pulled smooth, leaving enough slack to
accommodate anticipated shrinkage due to temperature changes. 360
xxii
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IV-13. Sufficient seam overlap must be maintained. 361
IV-14. Typical factory seam and field seam lap jointed. 362
IV-15. The surfaces to be "seamed must be cleaned to remove dirt. 363
IV-16. Seaming crews working with solvents aer advised to use gloves
for protection. 364
IV-17. Field seaming. 365
IV-18. Rolling the seam. 366
IV-19. Repairing a wrinkle at the seams. 367
IV-20. Trench and backfill design for anchoring the perimeter of a
membrane liner at the top of the pond sidewalls. 368
IV-21. A commonly used flange type seal around penetrations. 370
IV-22. An example of a technique for sealing around penetrations
using the boot type method. • 371
IV-23. Splash pad construction using a concrete subbase. 372
IV-24. Sluice type trough constructed of liner material. 373
IV-25. Typical design details for floating and fixed aeration systems. 373
V-l. Required capacity of leachate collection pipe. 375
V-2. Sizing of leachate collection pipe. 376
V-3. Pipe installation - conditions and loading. • 378
V-4. Projecting condition - pipe load coefficient. 379
V-5. Trench condition - pipe load coefficient. 381
V-6. Selection of pipe strength. 384
V-7. Typical leachate collection drains. 387
VI-1. Sketch of the flow system. 390
xxiii
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LIST OF TABLES
Number Page
2-1. Physical Classes of Waste Liquids 5
2-2. Potential Organic Chemicals in Waste Liquids 10
2-3. Composition and Analysis of an Average Municipal Refuse
from Studies by Purdue University 12
2-4. Parameters for Characterizing MSW Leachate 13
2-5. Composition of Three MSW Landfill Leachates 14
2-6. Characteristics of MSW Leachates 15
2-7. Representative Hazardous Substances Within Industrial Waste Streams 17
2-8. Typical Electroplating Solutions 19
2-9. Characterization of Waste Stream from Electroplating Industry 21
2-10. Hazardous Wastes Destined for Land Disposal from the Electroplating
and Metals Finishing Industry (Job Shops) 22
2-11. Potentially Hazardous Waste Streams Generated by the Metal
Smelting and Refining Industry 24
2-12. Ranges of Concentrations ana Total Quantities for Refinery Solid
Waste Sources 27
2-13. Raw Waste Constituents from the Pharmaceutical Industry 29
2-14. Chemical Analysis of Primary and Secondary Treatment Sludges
from the Pulp and Paper Industry 30
2-15. Elemental Maximum Concentrations and Other Parameters in Various
Waste Streams from Coal Combustion 33
2-16. Range of Concentrations of Chemical Constituents in FGD Sludges
from Lime, Limestone, and Double-Alkali Systems 34
2-17. Composition of Boiler Slowdown 36
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Number Page
2-18. Fireside Wastewater Characteristics 37
2-19. Ion Exchange Regeneration Wastes 37
2-20. Annual Solid Waste Production Statistics at Surface and Under-
ground Mines - Metals 38
2-21. Annual Solid Waste Production Statistics at Surface and Under-
ground Mines - Nonmetals 39
2-22. Common Flotation Reagents Used in the Recovery of Minerals
from Ores 40
3-1. Classification of Liners for Waste Disposal Facilities 46
3-2. Typical Values for Properties of Kaolinite, Illite, and
Montmori 1 lonite , 49
3-3. Composition and Properties of Admixed and Asphalt Membrane
Liners - Unexposed and After Exposure 68
3-4. Permeability of Asphalt Concrete to Water 70
3-5. Polymer Producers 74
3-6. Polymeric Materials Used in Liners • 76
3-7. Appropriate or Applicable Test Methods for Unexposed Membrane
Liners 89
3-8. Bonding Systems Available for Seaming Polymeric Membrane Liners
in Factory and Field 98
3-9. Representative Soil Sealants 104
4-1. Interlayer Spacing of Calcium Smectite as a Function of
Dielectric Constant and Dipole Moment 118
4-2. Interlayer Spacing of Calcium Smectite Immersed in Liquids of
Various Dielectric Constants 119
4-3. Descriptions of the Four Clay Soils Used in Study 126
4-4. Selected Properties of the Organic Test Liquids 128
4-5. Depth of Penetration with Time .for Benzene and Tap Water
Percolating through a 90 cm Column of Compacted Clay 138
4-6. Permeability of Noncalcareous Smectitic Clay Soil 141
XXV
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Number Page
4-7. Testing of Polymeric Membrane Liners 145
4-8. Effect on Properties of Polymeric Membrane Liners of 12 and
56 Months Exposure to Leachate in MSW Landfill Simulator 147
4-9. Water and Leachate Absorption by Polymeric Liners 150
4-10. Analysis of Leachate 151
4-11. Swelling of Polymeric Membranes on Exposure to MSW Leachate 152
4-12. Retention of Modulus of Polymeric Membrane Liner Materials
on Immersion in Landfill Leachate 154
4-13. Properties of PVC Membrane Specimens Before and After Exposure
to Leachate in MSW Landfill Simulators 156
4-14. Properties of 30 mil Polyvnyl Chloride Liner Recovered from
a Demonstration Landfill in Crawford County, Ohio 158
4-15. Properties of 15 mil Polyvinyl Chloride Liner Membrane Exposed
at a Sludge Lagoon in the Northeast for 6.5 Years 160
4-16. Effects on Chlorosulfonated Polyethylene, Low-Density Poly-
ethylene and Chlorinated Polyethylene Sheetings of Exposure
in MSW Cells at Boone County Field Site for 9 Years 161
4-17. Exposure of Unsupported CSPE Liner in Pilot-Scale MSW Landfill
Cells at Georgia Institute of Technology 163
4-18. Wastes in Exposure Tests (Pnases) 165
4-19. Wastes in Exposure Tests (pH, Solids, and Lead) 165
4-20. Volatiles and Extractables of Primary Polymeric Membrane
Liner Specimens after Exposure to Selected Wastes 167
4-21. Retention of Ultimate Elongation and S-100 Modulus of Primary
Polymeric Membrane Liner Specimens on Exposure to Selected
Wastes 168
4-22. Absorption of Waste by Polymeric Membrane on Immersion in
Selected Wastes 170
4-23. Volatiles Content of Flexible Polymeric Liners on Immersion
in Selected Wastes -. 171
4-24. Relative Permeabilities of Polymeric Membrane Lining Materials
in Pouch Test with Three Wastes 173
xxvi
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Number Page
4-25. Permeability of Thermoplastic Polymeric Materials in Osmotic
Pouch Test 173
4-26. Pouch Test of Thermoplastic Membranes 174
4-27. Exposure of Elasticized Polyolefin as Liner of Small Tub
Containing an Oily Waite 175
4-28. Effects of Exposure on Selected Polymeric Membrane Liners in
Water Containing a Low Concentration of Dissolved Organic
Chemicals for 17.2 Months 176
4-29. Liner-Industrial Waste Compatibilities 184
4-30. Failure Categories 187
5-1. Factors to be Considered in the Site Planning/Construction
Process 206
5-2. Relevant Background Information Helpful During Site Selection
Process 207
5-3. Compaction Equipment and Methods 226
5-4. Moisture Content of Refuse 265
5-5. Summary of Water Balance Calculations 267
7-1. Costs of Flexible Polymeric Membrane, Plastic, and Rubber
Liners 292
7-2. Cost Estimates of Soil, Admix, and Asphalt Membrane Liners 293
9-1. Construction Procedures and Specification for Liners of
Waste Disposal Facilities 299
9-2. Properties and Test Methods Used in ASTM Membrane Lining
Specifications 302
9-3. Physical Requirements in the ASTM Specifications for Flexible
Membrane Linings 303
III-A-1. Recommendations for Tensile and Tear Testing for Immersion
Study 322
III-B-1. Failed Elasticized Polyolefin Liner-Exposed to Saturated and
Unsaturated Oils in Open Tub 326
III-E-1. Solvents for Extraction of Polymeric Membranes 341
xxvii
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Number - Page
IV-1. Equipment and Materials for Installation of Flexible
Membrane Liners 354
IV-2. Considerations During Liner Placement 355
VI-1. Left Hand Side of Equation 3 392
VI-2. Right Hand Side of Equation 3 392
VI-3. The Best and the Worst Combinations of Parameters Which Result
in hf « hd and hf » hd 393
VI-4. Left Hand Side of Equation 4 394
VI-5. Right Hand Side of Equation 4 394
VI-6. Left Hand Side of Equation 6 395
VI-7. Soil Liner Permeability K], Required to Restrict the Flux
at q = 3"/Year ' 395
VI-8. Values of the Term [hd(q/K.f)-1/(2 + 3>0] for Different
Values of hd, X , Kf, and c 396
VII-1. Design Criteria and Parameters 399
VI1-2. Capital Costs for Waste Impoundment Facility 401
VI1-3. Operating Costs for Impoundment Facility 401
VI1-4. Annual Cost for Impoundment Facility 402
VIII-1. Suggested Test Methods for Testing of Flexible Polymeric
Membrane Liners 407
VIII-2. Titles of ASTM Test Methods Used in Membrane Liner
Specifications 408
VIII-3. Suggested Standards for Unsupported Membrane Liners -
Crosslinked Membranes 409
VI11-4. Suggested Standards for Unsupported Membrane Liners -
Thermoplastic Membran-es 410
VIII-5. Suggested Standards for Unsupported Membrane Liners -
Partially Crystalline Membranes " ". 411
VIII-6. Suggested Standards for Fabric-Reinforced Membrane Liners -
Thermoplastic Coatings of CPE, Nitrile Rubber - PVC, EPDM,
and EIA 412
xxviii
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Number Page
VIII-7. Suggested Standards for Fabric-Reinforced Membrane Liners -
Thermoplastic Chlorosulfonated Polyethylene (CPSE) 413
xxix
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ACKNOWLEDGMENTS
This document was prepared by Matrecon, Inc., Oakland, California, under a
contract with the Municipal Environmental Research Laboratory, U.S.. Environ-
mental Protection Agency, Cincinnati, Ohio. Henry E. Haxo, Jr., was Principal
Investigator on this project.
The following personnel made contributions to the text.
Matrecon, Inc.:
Henry E. Haxo, Jr.
Suren Dakessian
Paul D. Haxo
Michael A. Fong
Richard M. White
Emcon Associates, San Jose, California:
John G. Pacey
Southwest Research Institute, San Antonio, Texas:
David W. Shultz
Michael P. Miklas
Texas A and M University, College Station, Texas:
Kirk W.. Brown
David C. Anders<"0
XXX
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CHAPTER 1
INTRODUCTION
Background
The Resource Conservation and Recovery Act (RCRA) of 1976, PL-94-580,
directed EPA to issue regulations establishing performance standards applicable
to owners and operators of facilities used to treat, store, or dispose of
hazardous wastes. The goal of RCRA is to ensure that these facilities are
designed, constructed, and operated in a manner that protects human health and
the environment.
On May 19, 1980, EPA issued general standards that identified which wastes
were hazardous and created a manifest system to monitor the movement of hazard-
ous wastes from the point of generation to final disposition. These general
standards also delineated basic performance objectives necessary to safely
handle and control hazardous wastes during generation, transport, treatment,
storage, and disposal. Specific standards for hazardous waste land treatment,
storage, and disposal (USD) facilities were published on July 26, 1982.
The principal means of protecting the environment and human health is to
prevent hazardous waste constituents from migrating out of the facility into
other areas. To a great extent, this can be accomplished by controlling liquids.
There are two avenues for controlling liquids. One is to minimize leachate
generation by keeping liquids out of the LTSD unit, and the other is to prevent
any liquids present in the unit from escaping into the surrounding environment.
Placing liners beneath the waste in LTSD units is a key element in control-
ling the escape of liquids. Liners must be viewed as components of a liquids
control system and not the definitive system itself. A liner is a barrier
technology that prevents or greatly restricts migration of liquids, thus facil-
itating their removal from the unit. No liner, however, can contain liquids
for all time. Eventually liners will either degrade, tear, or crack and will
allow liquids to migrate out of the unit. It is, therefore, important that
other measures be taken to remove liquids from the unit during the time that
the liner is most effective (i.e., during the active life of the facility).
Leachate collection and removal systems and measures to remove free liquids at
closure are the principal techniques used in conjunction with liners in an
effective liquids control system. After closure of disposal units, a protective
cap becomes the principal element in controlling liquids by preventing them
from entering a unit, thereby reducing the potential for leachate generation.
Purpose
This Technical Resource Document provides information on the performance,
selection, and installation of various lining and cover materials, based upon
current technology.
-------
The information is intended to assist the user in determining what liner
material (s) would be effective in containing specific hazardous wastes or waste
leachates. Effective control for disposal units means preventing hazardous
waste constituents from moving either into or through the liner. For storage
units where both the waste and liner system must be removed at closure, hazardous
waste constituents are allowed to Jiove into, but not through, the liner itself. (
Essential factors to consider in selecting appropriate liner materials are
0 compatibility of the specified wastes or waste leachates with liner materials;
0 compatibility of 1iner material s with supporting and surrounding environmental
elements at the unit site;
0 service life or period of time that the liner will be expected to contain the
specified wastes.
Cost analyses are described for selecting the most economical liner materials
of those found to be appropriate for a given situation.
After the appropriate liner materials have been selected, proper fabrication,
construction, and installation of the liner are critical processes that contribute
to successful onsite performance of the liner system. Careless or inappropriate
practices during these processes may cause otherwise exemplary liner materials
to fail. Considerations for ensuring proper construction and installation of
different liners and procedures for maintaining the integrity of the liner during
daily operations are discussed.
Scope
Chapter 2 describes various types of hazardous wastes and the constituents
that are aggressive toward different lining materials. Several industrial waste
streams are described to illustrate the type of waste liquids that may be in
contact with liners.
Lining technology and materials are presented in Chapter 3. These linings
include remolded and compacted soils and clays, admixes, polymeric membrane
liners, sprayed-on liners, soil sealants, and chemisorptive liners.
The performance characteristics of many liner materials under field condi-
tions with various types of wastes are discussed in Chapter 4, particularly
their compatibility with wastes, permeability to water and waste constituents,
failure mechanisms, and estimated service lives. Several testing procedures for
evaluating the waste/liner interaction, and some data from actual field units
are given.
Chapter 5 deals with the design and construction of LTSD units using various
types of lining materials. In particular, it discusses the installation of
membrane liners and associated problems. Attention Is given to the specific
requirements for site and surface preparation and the placing of protective soil
covers on membrane liners to prevent puncturing. Special problems associated
with-the design and construction of disposal units (i.e., landfills) and leachate
generation above the liner are also discussed.
-------
The operation, management, and maintenance of different disposal units
are described in Chapter 6. Particular attention is given to the facilities
that have membrane liners and ground-water monitoring. A plan for monitoring
the liners is suggested. Standard operating procedures are discussed, and a
section is included on inappropriate practices.
Chapter 7 outlines the historical costs of installing various liner materi-
als for different types of wastes in different parts of the country.
In Chapter 8, several methods for selecting a specific liner or a group
of satisfactory liners for a given containment unit are presented. These
include the use of compatibility tests, moderate duration exposure tests, soil
condition tests, prior performance in similar facilities, and costs.
Specifications for the construction of selected liners or groups of liners
are suggested in Chapter 9.
For those wishing to obtain additional information on specific topics,
each chapter lists references, and there is a complete bibliography at the end
of the vol ume.
More detailed information on certain subjects is presented in the appen-
dices. Appendix I is the Unified Soil Classification System. Appendix II
lists companies that provide liner materials and services. Test methods are
described in Appendix III. Other Appendices address flexible polymeric membrane
liner installation, leachate collection systems, soil liner design, and speci-
fications for flexible polymeric membrane materials. In addition, a methodol-
ogy for case study analysis of liner units is discussed. Because of the
diverse origins of liner technology and the broad spectrum of potential uses
of this document, a glossary of terms related to liner technology by pertinent
subject area is included.
This document refers to, but does not discuss, the following subjects:
1. Site selection, except when specific liners would be inappropriate.
2. Detailed discussion of methods of analysis of wastes, except for information
on waste components that are aggressive to linings of all types.
3. Monitoring of ground water.
4. Attenuation of pollutants in the native soil below the liner.
5. Legal aspects.
document attempts to bring together current knowledge and technology
related to. liners and the disposal of wastes. As new technology is developed
and as experience in the use of liners provides more information!, this document
will be modified and updated.
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CHAPTER 2
CHARACTERISTICS OF UASTES AND WASTE LIQUIDS
2.1 INTRODUCTION
From the standpoint of pollution control, waste containment, and groundwater
protection, we are primarily concerned with the waste liquids. Waste liquids
carry dissolved components which, because the liquids are capable of migrating
out of a disposal site, can enter and pollute the groundwater supply. Both the
liquids and the dissolved components in a waste leachate may interact with a
liner to alter its initially low permeability so that the polluting constitu-
ents can pass through the liner. Thus, the total composition of a waste
liquid is important in the evaluation of an impoundment liner material
for a given waste disposal facility.
According to a nationwide industry-sponsored survey (National Solid Waste
Management Association, 1981) -of land disposal practices conducted in 1980,
the United States had a total of :.2,627 active landfills. Of these landfills,
only 40 were reported to operate with liners and only 26 were listed as having
operational leachate treatment and control systems. The majority of the
active landfills are for municipal solid waste (MSW) and generally do not
accept industrial waste. In addition, the survey identified 109,839 active
industrial waste surface impoundments of which 69,490 were on-site facilities.
No information was reported on iow many of these surface impoundments had
liners or active leachate control.
Approximately 15% of all industrial wastes (57 million metric tons, wet
weight, per year) is classified as hazardous (Hanrahan, 1979; EPA, 1980d).
EPA-sponsored industrial studies conducted from 1975 through 1978 indicated
that 78% of all hazardous waste in the United States is disposed of in unlined
landfills or surface impoundments., whereas only 2% is disposed of in "secure
landfills" (EPA, 1980b).
Cheremisonoff et al (1979) estimated that 90% by weight of industrial hazard-
ous wastes are produced as liquids. These liquids are further estimated to
contain solutes in the ratio .of 40% inorganic to 60% organic. _ The hetero-
geneous nature of most wastes' greatly complicates attempts to predict their
effects on the integrity of disposal site liners. At the present state-of-
the-art it is not possible to predict liner performance adequately based upon
the composition of the waste liquid.
This chapter begins with a classification scheme for wastes according to the
liquids and dissolved components; present in a waste; then discussed are
-------
chates generated by wastes, liquids that may be in the leachates, and the
lved components that are carried by these liquids. Finally, the chapter
nts examples of significant waste sources and the types of waste gen-
ted by these sources. Selected representative wastes of the following
es are discussed:
- Municipal solid waste.
- - Hazardous wastes from eight industries.
- Other nonradioactive wastes.
is discussion is intended only to be illustrative. The objective is to give
imples of wastes from the different industries that may be encountered and
ich may or should be impounded in lined facilities. Interactions between
5tes and specific liner materials are discussed in Chapter 4.
. 2 CLASSIFICATION AND GENERAL CHARACTERISTICS OF WASTE LIQUIDS
AND LEACHATES
stes that are disposed of on land can be classified in a variety-of ways,
r example, they can be classified by industry source, by physical charac-
ristics, and by chemical composition. Regardless of the type of waste, the
iportant factor with respect to liners and their performance is the leachate
• liquid generated by the waste and the composition of the leachate. Fur-
lermore, the leachate generated in landfills can arise from two sources,
.e. , from the waste itself and from water that enters the fill and leaches
iter soluble components.
liquids generally fall i_nto the following four classes: aqueous-inor-
c, aqueous-organic, organic, and sludges, as shown in Table 2-1 (EPA,
.
TABLE 2-1. PHYSICAL CLASSES OF WASTE LIQUIDS
31ass of waste 1 iquid
\queous-i norgani c
^queous-organix:
Organic
Sludges
Solvent
Water
Water
Organic liquid
Organic liquid or water
Solute
Inorganic
Organic
Organic
Organic and inorganic
\queous-inorganic liquid wastes are those in which water is the liquid phase
ind the dissolved components are predominantly inorganic. Examples of these
dissolved components are inorganic salts, acids, bases, and dissolved metals.
Examples of waste liquids in this category are brines, electroplating wastes,
netal etching wastes, and caustic rinse solutions...
Aqueous-organic liquid wastes are those in which water is the liquid phase and
the dissolved components are predominantly organic. Examples of these dis-
solved components 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 ethylene glycol production wastes.
Organic liquid wastes are those tha-: have an organic liquid phase and the
dissolved components are other organic chemicals dissolved in the organic
liquid. Examples of this class of wastes are oil-based paint waste, pesticide
manufacturing wastes, spent motor oil, spent cleaning solvents, and solvent
refining and reprocessing wastes.
Sludges represent the fourth class of wastes. They are generated when a waste
stream is dewatered, filtered, or treated for solvent recovery. Sludges are
characterized by high solids content such as those found in settled matter of
filter cakes and consist largely of clay minerals, silt precipitates, fine
solids, and high molecular weight hydrocarbons. Examples of this class of
waste are American Petroleum Institute (API) separator sludge, storage tank
bottoms, treatment plant sludge, and filterable solids from any production or
pollution control process.
/
Both economic and pollution control factors give impetus to solvent recovery
and reductions in the discharge of 1'iquid wastes. These factors make sludges
the fastest, growing class of wastes. After the placement of a sludge in a
waste disposal facility, liquid or leachate migrates out of the sludge due to
gravitational forces, overburden pressures, and hydraulic gradients. These
leachates are similar in form to the first three classes of wastes shown in
Table 2-1.
2.3 LIQUIDS GENERATED BY WASTE
Two types of liquids can be generatec in a given waste (Anderson, 1981). These
liquids are (1) the flowable constituents of the waste, which were either in
the waste originally or generated by decomposition, and (2) the flowable
material generated by water percolating through the waste and leaching soluble
constituents (Figure 2-1).
The flowable components of the waste are often referred to as the primary
leachate and include both. the liquids in the waste and the dissolved con-
stituents. A primary leachate may be aqueous-organic, aqueous-inorganic, or
organic.
Leachate generated from water percolating through the waste is composed of
water and the dissolved components or solutes. This flowable mixture is often
referred to as secondary leachate and may be aqueous-organic or aqueous-inor-
ganic, depending on the waste composition. Both forms of leachate combine at
the bottom of the fill and would be in contact with the liner.
The predominant liquid in.a leachate may be water.or an organic liquid. The
solutes in a leachate are either liquids or solids that dissolve in the liquid
phase. Primary and secondary leachates each consist of a liquid carrier and
dissolved constituents, both of which may affect the permeability of a liner,
regardless of the type of liner.
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HYDRAULIC AND
BEARING PRESSURE
OUTSIDE WATER
LIQUID PORTION OF
THE WASTE
HAZARDOUS WASTE
WATER SOLUBLE
PORTION OF THE WASTE
PRIMARY LEACHATE
SECONDARY LEACHATE
LINER
LINER
! UNDERLYING
"»*»?W0'^!3W*j*»«i^*i.«<£>»»»'.- * •»&,,
.S'TRATA
-
Figure 2-1. Sources of primary and secondary leachates generated by wastes.
The liquid carrier will usually exert a dominating influence on the permea-
bility of clay soil liners. However, dissolved constituents, whether in-
organic or organic, can also affect the properties of a liner, depending upon
the liner. For example, over long exposures, minor amounts of dissolved
organics can affect asphaltic and some polymeric liners.
Essentially all available literature describing leachates generated in waste
disposal sites considers water as the liquid carrier and organic chemicals to
be present in only small quantities (Chian and DeWalle, 1977). While this may
be the case at the interface of secondary leachate and a water table, the
liquid phase at the interface of primary leachate and the disposal site liner
will depend on the class of waste being disposed of. An organic waste or
sludge with an organic liquid phase will most probably expose the liner to the
organic liquids contained in the waste. The examples given in subsequent
sections of this chapter show t-hat the organic liquids disposed of in in-
dustrial landfills cover the spectrum of chemical species.
2.3.1 Liquids In Waste Leachate - -
For the purpose of experimentally determining or assessing the effects organic
liquids may have on the integrity of a lining material, the liquids have been
-------
classified into four groups. These groups are based on the physical and
chemical properties that govern their interactions with liner materials.
These properties include acidity, basicity, polarity (Debye, 1929), and
solubility parameters of the organ-c components (Hildebrand and Scott, 1950).
The latter properties are of particular importance with polymeric and as-
phaltic liners. (Figure 2-2).
WASTE LIQUID
ORGANIC: LIQUIDS
AND/OR DISSOLVED
SOLIDS
ACIDS
1 BASES
-NEUTRAL
POLAR COMPOUNDS
NEUTRAL.
NON-POLAR COMPOUNDS
INORGANIC SOLIDS
-DISSOLVED
1—ACIDS
BASES
1— SALTS
Figure 2-2.
Generalized composition of waste liquids that may contact a liner
in service, showing the components that may be present. For
actual wastes, the ratios of components will vary greatly but
water is generally the principal component; the organics will be
dissolved in the water as will be the inorganics. The liquid
phase can be wholly organic with other dissolved organic liquids
or solids and inorganics. Also, the organics could be present
in emulsified or suspended states in the water.
Liquid organic acids are organic compounds with acidic functional group$ such
as phenols and carboxylic acids. Proton-donating properties of Bronsted
acids give these fluids potential to react with and dissolve soil liner
components. An-ever present source of liquid organic acids in municipal solid
waste impoundments is anaerobic decomposition byproducts. These include
acetic, propionic, butyric, isobutyric, and lactic acids. Anaerobic decom-
position yields carboxylic acid derivatives of other organic liquids placed in
the impoundment.
-------
II
Bronsted organic bases (such as aniline) may be liquid and have been used
as solvents in several industries. While it is not clear if organic bases are
strong enough proton acceptors to dissolve soil liner components, inorganic
bases are. Both inorganic acids and bases are discussed in the next sub-
section.
Neutral polar organic liquids do not exhibit a net charge but have an asym-
metrical distribution of electron density resulting in an appreciable dipole
moment, an indicator of polar character (Oebye, 1929). Examples of such polar
compounds are alcohols, aldehydes, ketones, glycols, and alkyi halides.
Neutral nonpolar organic liquids have no net charge and small, if any,
dipole moments. These liquids have low water solubilities and little po-
larity. Examples of nonpolar organic liquids are aliphatic and aromatic
hydrocarbons (Table 2-2).
Water has a large dipole moment and is present in all wastes to some extent.
Water may infiltrate the cover of a disposal facility or be released from a
waste as a decomposition byproduct.
In the case of polymeric liners, the relative solubility parameters of the
polymer and the organic solvents that are present, either alone or in solu-
tion or dispersed in the water, can have major effects on the liner. When the
solubility parameters of the solvent and the polymer are close, severe swel-
ling of the liner and even dissolution can occur.
2.3.2 Dissolved Components in Waste Leachate
Organic and inorganic chemicals are dissolved in the leachate of a waste,
regardless of the composition of the principal liquid of the waste. However,
the relative abundance of a given dissolved component will depend on the
composition of the principal liquid. For instance, if the liquid is neutral
nonpolar organic, it will have a large carrying capacity for other neutral
nonpolar organic cheniicals. If the liquid phase is predominantly aqueous, its
carrying capacity for nonpolar organics in its dissolved phase will be rela-
tively small.
Water has a relatively large carrying capacity for polar organic chemicals
(they ma£ be miscible in each other in all proportions) and for inorganic
acids, bases, and salts. Strong inorganic acids and bases, which are in-
variably water-based, may be especially aggressive to liner materials.
2.4 MUNICIPAL SOLID WASTE
2.4.1 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,
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and garden wastes, ceramics, rocks, textiles, leather, etc. Major
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2.4.2 Characteristics of Leachate From Municipal Solid Waste
a leachate produced from municipal refuse is a highly complex liquid
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TABLE 2-5. COMPOSITION OF
Concentration of Constituents (mg/L)
THREE MSW LANDFILL LEACHATES
, Except pH and Electrical Conductivity
Constituent
BOD5
COO
TOC
Total solids
Volatile suspended solids
Total suspended solids
Total volatile acids as acetic acid
Acetic acid
Prop ionic acid
Butyric acid
Valeric acid
Organic nitrogen as N
Ammonia nitrogen as N
Kjeldahl nitrogen as N
pH
Electrical conductivity (ymho/cm)
Total alkalinity as CaCOi
Total acidity as CaC03
Total hardness as CaC03
Chemicals and metals:
Arseni c
Boron
Cadmi urn
Calci urn
Chloride
Chromium
Copper
Iron
Lead
Magnesium
Manganese
Mercury
Nickel
Phosphate
Potassium
Silica
Sodi urn
Sulfate
Zinc
Wigh,
1979
• • •
42,000
* • •
36,250
• • •
* • «
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• • *
• • •
• • •
* • •
• • •
950
1,240
6.2
16,000
8,965
5,060
6,700
• • •
• • •
• * •
2,300
2,260
• • •
* • •
1,185
• • •
410
58
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* « •
82
1,890
• • •
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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
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3,460
5,555
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180
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185
• * •
260
18
• • •
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1.3
500
• • •
160
• • •
• • •
Griffin
and Shimp,
1978
• • •
1,340
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333
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862
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6.9
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2.4.4 Potential Effects of MSW Leachate Upon Liners
MSW leachate is not inert toward 1-ning materials; constituents of the leach-
ate can affect liners in different ways, depending on their concentrations 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 concentra-
tions 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 mole-
cules (indicated by volatile acid content, volatile solid, and COD) 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. Water also can cause
some liners to swell. These effects are discussed in detail in Chapter 4.
Also discussed in Chapter 4 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.
2.4.5 Gas Production in MSW
Gases are also produced in the decomposition of organic: matter in MSW land-
fills. 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 leachate and tends
to lower pH and thus to solubilize calcium, magnesium, and other metals.
2.5 HAZARDOUS AND TOXIC WASTES BY INDUSTRY
Industrial wastes are a major source of hazardous wastes, the components
of the latter are usually heavy metals, strong acids or bases, and a large
array of organic and inorganic chemicals. As shown in Table 2-7, 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
chemical nature and reactivity, as well as concentration of the waste com-
ponents, must be considered when choosing a liner 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
may be encountered and may have to be placed in lined facilities. Special
attention is given those constituents in the waste liquids that are aggres-sive
to liners.
2.5.1 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
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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 iray be hazardous; appropriate tests should be
run to determine whether the waste liquids are hazardous.
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 electroplating
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 func-
tional 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 discharges,
and maintenance discharges (EPA, 1979).
Treatment may involve degreasing with soaps, alkalina cleaning (sometimes
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 2-8 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 par-
ticular 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 precipitating
chelated metals out of wastewater during treatment.
Wastes from metal finishing operations..come from -cleaning, pickling, anodiz-
ing, 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
18
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TABLE 2-8. 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/litre
Cadmium oxide
Cadmi urn
Sodium cyanide
Sodium hydroxide
Cadmium fluoborate
Cadmium (as metal )
Ammonium fluoborate
Boric acida
Licorice
Chromic acid
Sulfate
Fluoride
Copper cyanide
Free sodium cyanide
Sodium carbonate
Rochelle salt
Copper nitrate
Sodium bicarbonate
Rochel le salt
Sodium hydroxide
Formaldehyde (37%)
Gold (as potassium
gold cyanide)
Potassium cyanide
Potassium carbonate
Dipotassium phosphate
Nickel sulfate
Nickel chloride
Boric acid
Si 1 ver cyanide
Potassium cyanide
Potassium carbonate (min)
Metallic silver
Free cyanide
Zinc sulfate
Sodi urn "s'ul fata " "
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/I
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.
19
-------
usually contain metal salts, acids, bases, dissolved basis metals, complexing
agents, and other deposition control agents. Bath constituents for chemical
removal of basis metals include mineral acids, acid chlorides, alkaline
ammonium solutions, nitro-organic compounds, and such compounds as ammonium
peroxysulfate.
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 2-9 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 2-10.
2.5.2 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
20
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TABLE 2-10. 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
Source: Hallowell et al ,
1975
19,740
42,141
5,434
11,422
78,737
1976.
1977
56,399
42,141
5,434
11,422
115,396
1983
73,882
55,206
7,118
15,063
151,269
reclaimed are usually disposed of in lined impoundment facilities (Hallowell
et al, 1976).
2.5.3. 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 generated
by metal smelting and refining and the constituents of these waste streams
22
-------
that are considered potentially hazardous or aggressive to lining materials
are given in Table 2-11.
2.5.4 Organic Chemicals Industry
The petrochemical and organic chemicals industry is second only to petroleum
refining in the volume of hazardous wastes it generates. Industrial petro-
chemical 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 products such as plas-
tics, rubber, Pharmaceuticals, paints, pesticides, organic pigments, inks,
adhesives, explosives, soaps, synthetic fibers, and cosmetics. 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 pesti-
cides, Pharmaceuticals, rubber, and olastics, 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 constituents as
well as inorganic (EPA, 1975b).
2.5.5 Pair" 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 pollution
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
23
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returned to the plant for reuse. Waste wash solvents are also incinerated and
some are placed in drums that are landfilled.
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, Inc., 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 aggressive
to liners based on asphalt, polymers, and, in some cases, clay soils.
2.5.6 Pesticide Industry
The diverse nature of the pesticide industry and the wide distribution of the
products make it difficult to analyze and assess the pollution 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 different 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 ad-
dition, many pesticides are registered for intrastate sale only; an estimated
2,000 pesticidal products are registered in California alone (Wilkinson et al,
1978).
Many pesticide wastes are aqueous solutions o.r 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, 1974).
Pesticide wastes result largely from the periodic cleaning of formulation
lines, filling equipment, s,pi11s, area washdown, drum washing, air pollution
control devices, and area runoff. Wash waters and steam condensates 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.
25
-------
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 effec-
tively 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 concen-
trated. The concentrated waste would be disposed of in a landfill, or
stabilized or containerized and then placed in a landfill.
2.5.7 Petroleum Refining Industry
Different waste streams generated by the petroleum refining industry vary
with the refining process. Highly caustic sludges result from operations
including washing, sweetening, and neutralizing. Spent caustic solutions are
discharged from alkylation, and isomerization units, and LPG treating pro-
cesses. 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 weigtit. Refer to Table 2-12 for concentrations and quantities of several
wastes resulting from refining processes.
The oils, organics, high pH, and h:gh 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).
2.5.8 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 2-13 for raw waste sources and
constituents. Biological wastes result from the production of vaccines,
serums, and other products derived or extracted from plant and animal sources.
26
-------
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28
-------
TABLE 2-13.
RAW WASTE CONSTITUENTS FROM THE PHARMACEUTICAL INDUSTRY
(g/kg Production)
Fermentation
Biological products and
natural extractive man-
facturing
Chemical synthesis
Formulation
Research
TDS
5.990
895
1.060
11.3
1.33
,X03-«
4.63
0.02
0.20
0.053
Trace
Total
P
22.0
7.3
7.83
0.15
0.23
011
and
grease
413
3.62
21.6
0.78
(a)
Cl
1.260
211
104
2.51
0.94
S04
274
277
203
0.52
1.27
Sulfide
(a)
U)
...
0.007
(a)
Total
Hard-
ness
294
...
61.6
5.32
Ca
123
36.4
15.2
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.
aOata not reoorted.
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.
2.5.9 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 activities of this
industry that produce wastes include chemical wood pulping, wastepaper pulp-
ing, pap.er 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 reclamation wastes. Table
2-14 presents analyses of various sludges that are generated by the pulp and
paper industry.
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 2-14. Fortunately, a
large proportion of the.plants using this process recycle many of their
wastes, including the burning of the lignin as fuel.
Wastewater treatment sludges artse from primary
and flotation, and secondary treatment „_ _.._
of specific pollutants may vary widely,
filtration . . _.._
aerated lagoons. The concentration or speci
depending upon the fibers and processes used.
treatment such as settling,
in activated sludge and
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
29
-------
TABLE 3-H. CHEMICAL ANALYSIS OF PRIMARY AMD SECONDARY TREATMENT SLUDGES FROM THE PULP AND PAPER INDUSTRY
Constituent*
Water (i)
Solids (S)
Asn (!)
COO
Phenol
PC8
011 and grease
Total nitrogen
Aluml num
Cadmium
Calcium
Chloride
Chromium
Copper
Iron
Lead
Magnesium
Manganese
Nickel
Phosphorous
Potassium
Sodium
Sulfate
Zinc
Primary and secondary
sludge from semt-
chefflical pulping
90-96
4-10
1-2.5
50,300-120,000
5
<13
1
1,400
• « •
1.5
4 , QOO- 1 5 , 000
• • •
• < •
N0°
• . .
120
• • •
250
25
• * •
1,600
1,400
120
260
Oe-mkirg sludge Pretreatment Board ComDined primary
(11 (recycled De-inking sludge from mil and
pacer) sludge *2 paper coating sludge secondary sludge
77.06
22 4
21.3IJ6
!2
4,310
3.12
,!0 £
86
14
. . .
400,000
100,
JO
330
5.18 1,500 200,
:i2 1,300
l.UO
16
2.3 S 3,0
310
114
146
0.03
40
50
40
w t
t
t
.
f
4
<
'79
62
2,400
f
.
.
4
t
6
.
.
6
t
.
380 47
. * .
1,146
0 52
2
. • •
...
. . .
151 300 4,000 350 397
Source: Energy Resources Co. (1979) and SPA (1979)
i\n ppm unless otherwise noted.
DNO > Mot detected.
metals. The coal ashes are similar
power industry.
to those discussed under the electric
2.5.10 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
constituents 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 organic chemical:; Magnesium
Oils and greases Manganese
pH Mercury
Phenolic compounds ., Holybdenum
Phosphates . Nickel
Sulfides Vanadium
Temperature Zi nc
Turbidity
30
-------
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 800 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 dam-
aging to various lining materials (Landreth, 1978). Concentrations of in-
dividual 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).
2.5.11 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 pro-
duction 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 COD,
8005, TDS, 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 potential
synergistic effects it may have upon a liner by creating a broader dispersion
of pollutants from mixing.
2.6 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 indus-
tries generate large quantitites of wastes, some of which are potentially
hazardous and may have to be impounded in lined storage or disposal facili-
ties. 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 antic-
ipated growth of the industries, some of the specific wastes are described
and briefly discussed in the following subsections.
2.6.1 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 are
hazardous. The latter group includes:
- Air preheater waste water.
- Coal pile drainage.
- Cooling water, once through.
31
-------
- Cooling water, recirculating.
- Metal cleaning waste water:
Boiler, fireside.
Boiler, waterside.
- Water treatment wastes, especially brines.
- Miscellaneous wastes, such as equipment
washdown, floor drainage, and sanitary
wastes.
2.6.1.1 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. f:ly 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 charac-
teristics, coal preparation prior to combustion, and the type of boi-ler
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 poncing (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 2-15 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 desul-
furization (FGD) sludges vary widely in composition and characteristics.
Unstabilized FGD sludge is pseudo-thixotropic in most cases, thus posing a
significant potential for pollution. Stabilized FGO 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 2-16 show the range in values of
several constituents and parameters for three different FGD systems. Addi-
tional data and information is available (EPRI, 1979 and 1980; Leo and
Rossoff, 1978).
32
-------
TABLE 2-15. ELEMENTAL MAXIMUM CONCENTRATIONS AND OTHER
PARAMETERS IN VARIOUS WASTE STREAMS FROM COAL COMBUSTION
Element
Al
Sb
As
Ba
Be
B
Cd
Ca
C1
Cr
Co
Cu-
F
Ge
Fe
Pb
Li
Mg
Mn
Hg
Mo
Ni
P
K
Se
Si
Ag
Na
Sr
Ta
T1
V
Zn
Zr
PH
TDS
TSS
Bi
S04
Flyash
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
Flyash
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
* • *
• • •
* • •
• • •
• • •
* • •
Source: EPRI, 1978, pp 94 and 95.
33
-------
TABLE 2-16
RANGE OF CONCENTRATIONS OF CHEMICAL CONSTITUENTS IN FGD SLUDGES
FROM LIME, LIMESTONE, AND DOUBLE-ALKALI SYSTEMS
Scrubber Constituent
Aluminum
Arsenic .
Beryl lium
Cadmium
Calcium
Chromi urn
Copper
Lead
Magnesium
Mercury
Potassium
Seleni urn
Sodium
Zinc
Chloride
Fluoride
Sulfate
Sulfite
Chemical oxygen demand
Total dissolved solids
pH
Liquor Concentration
mg/L (except pH)
0.03
0.004
0.002
0.004
180
C.015
0.002
0.01
4.0
0.0004
5.9
0.0006
10.0
0.01
420
0.6
600
0.9
1
2,300
4.3
- 2.0
- 1.8
- 0.18
- 0.11
- 2,600
- 0.5
- 0.56
- 0.52
- 2,750
- 0.07
- 100
- 2.7
- 29,000
- 0.59
- 33,000
- 58
- 35,000
- 3,500
-• 390
- 92»500,
- 12.7
Solids, mg/kg
• • •
0.6 - 52
0.05 - 6
0.08 - 4
105,000 - 268,000
10 - 250
8 - 76-
0.23 - 21
• • •
0.001 - 5
• • •
2-17
48,000
45 - 430
9,000
* • •
35,000 - 473,000
1,600 - 302,000
\
• • •
r"- ., *.
• • •
• • •
Source: Leo and Rossoff, 1978.
34
-------
2.6.1.2 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 1980e, 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 2-17. 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 cleanec !PA, 1974b, p 147). The cleaning
solution often contains alkalis to dissoU; oil and grease, and detergents to
keep the removed material in colloidal suspension (Table 2-18).
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 2-19. 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
1980e, 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 makeup water for sluicing ashes from boilers or for sulfur
dioxide scrubbing solution (EPA, 1974b, p 115; EPA 1980e, 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.
2.6.2 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 the specific
streams with respect to future liner usage. There are other factors such as
35
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TABLE 2-17. COMPOSITION OF
Pollutant
Conventional measures of pollution
PH
Total solids
Total suspended solids
Total dissolved solids
BOD5
COD
Hydroxide alkalinity
Oil and grease
Major chemical constituents
BOILER SLOWDOWN
Concentration, mg/L
8.3 - 12.0
125 - 1,407
2.7 - 31
1.08 - 11.7
10 - 1,405
2.0 - 157
10 - 100
1 - 14.8
Phosphate (total) 1.5 - 50
Ammonia 0..0 - 2.0
Cyanide (total) 0.005 - 0.014
Trace metals
Chromium (total )
Chromium"1"**
Copper
Iron
Nickel
Zinc
ca 0.02
0.005 - 0.009
0.02 - 0.19
0.03 - 1.40
ca 0.030
0.01 - 0.05
Source: EPRI, 1978, p 58.
total pollution potential, which were also considered. Tables 2-20 and 2-21
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 im-
poundments. 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 tailing
is shown i-n Table 2-22. Most of the organics, such as hydrocarbons, alcohols,
and ethers that remain in the tailings water evaporate, decompose, or bio-
degrade. 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 dif-
ficulty with these liquids is that they are" complex blends of components
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 capabilities have
36
-------
TABLE 2-18. 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
Virtual
Average
1.5
0.02
4.0
70
6.0
2.0
2,500
3.5
1,000
5,000
250
ly absent
Source: EPA, .*8Qe, p 213.
TABLE 2-19. ION EXCHANGE REGENERATION WASTES
Pollutant
pH (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
Mi nimum
value
1.7
3.0
1,894
0.1-3
Maximum
value
10.6
305
9,645
22
Source: EPA, 1980e, p 187.
37
-------
developed greatly in recent years; therefore, an accurate compositional
analysis can generally be made of any given liquid. The fluid must be
characterized to determine its major constituents.
TABLE 2-20. ANNUAL SOLID WASTE PRODUCTION STATISTICS AT SURFACE
AND UNDERGROUND MINES3 - METALS
(In thousand short tons)
Industry
segment
Bauxite
Copper
Gold
Iron
Lead
Molybdenum
Si 1 ver
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
mi nerals
<1
29
1
20
<1
2
<1
<1
14
<1
1
68
Source: PEDCO, 1981.
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 1978-7y i-n nerals Yearbook.
^Antimony, beryllium, manganiferrous ore, mercury, nickel, rare earth
metals, tin, and vanadium.
eQuantitative information on these wastes are not compiled since rel-
atively insignificant amounts are generated.
38
-------
TABLE 2-21, ANNUAL SOLID WASTE PRODUCTION STATISTICS AT SURFACE
AND UNDERGROUND MINES3 - NONMETALS
(In thousand short tons)
Percent of total
Mine for all non-coal
waste" Tailings0 Total minerals
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, py-
rophyl lite
Total
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
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
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
<1
2
(d)
<1
<1
<1
<1
25
<1
<1
<1
<1
<1
4
<1
<1
32
Source: PEDCO. 1981.
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.
dQuantitative information on these wastes . -e not compiled since relatively
insignificant amounts are generated.
39
-------
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-------
REFERENCES
Chapter 2 - Characteristics of Wastes and Waste Liquids
Anderson, D. C. 1981. Organic Leachate Effects on the Permeability of Clay
Soils. M.S. Thesis, Soil and Crop Sciences Dept., Texas ASM Univer-
sity, College Station, TX.
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-440/1-74/01Oa. U. S. Environmental Protec-
tion Agency, Washington, DC. 247 pp.
Becker, 0. 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-440/1-75-036b. U. S.
Environmental Protection Agency, Washington, DC. 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. Cannes. 1974. Characteristics of Percolate of
Solid and Hazardous Wastes Deposits. Presented at AWWA (American Water
Works Association) 4th Annual Conference. Boston, MA. 23 pp.
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. 8. Dewalle. 1977. Evaluation of Leachate Treat-
ments. EPA-600/2-77-186 a,b. U. S. Environmental Protection Agency,
Cincinnati, OH. 2 vols. - •- ,
Debye, P. 1929. Polar Molecules. Reinhold, New York. (Reprinted by Dover
Publications, NY.) 172 pp.
41
-------
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, DC.
EPA. 1974a. Report to Congress: Disposal of Hazardous Wastes. SW-115.
U. S. Environmental Protection Agency, Washington, DC. 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. U. S. Environmental Protec-
tion Agency, Washington, DC. 865 pp. (NTIS PB 240 853).
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, DC. 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, DC. 392 pp.
EPA. 1977. Procedures Manual for Groundwater Monitoring at Solid Waste
Disposal Facilities. EPA-53C/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, DC. 427 pp.
EPA. 1980a. Test Methods for Evaluating Solid Waste: Physical/Chemical
Methods. SW-846. U. S. Environmental Protection Agency, Washington,
DC. .
EPA. 1980b. Everybody's Problem: Hazardous Waste. SW-826. U. S. Environ-
mental Protection Agency, Washington, DC. 36 pp.
EPA. 1980c. Hazardous Waste Management System: Standards for Owners and
Operators of Hazardous Waste Treatment Storage and Disposal Facilities.
Fed. Regist. 45(98).
EPA. 1980d. Research Outlook 198G. EPA 600/9-80-006. U. S. Environmental
Protection Agency, Washington, DC. 224 pp.
EPA. 1980e. Development Document for Effluent Limitations Guidelines and
Standards for the Steam Electric Point Source Category. EPA 440/1-80-
0296. U. S., Environmental Protection Agency, Washington, DC. 597 pp.
EPRI. 1978. Characterization of Fly Ash and Related Metal Oxides Using Auger
Electron Spectroscopy. EPRI FP 708. Electric Power Research Institute,
Palo Alto, CA. 114 pp.
42
-------
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. FGO Sludge Disposal Manual. 2nd ed. CS-1515. Research Project
1685-1. Electric Power Research Institute, Palo Alto, CA.
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, DC.
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, DC.
Genetelli, E. J., and J. Cirello, eds. 1976. Gas and Leachate from Landfills:
Formation, Collection, and Treatment. EPA 600/9-76-004. U.S. Environ-
mental 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-440/1-74-018a. U. S. Environmental Pro-
tection Agency, Washington, DC. 202 pp.
Griffin, R. A., and N. F. Shimp. 1978. Attenuation of Pollutants in Munici-
pal Landfill Leachate by Clay Minerals. EPA-600/2-78-157. U. S. Envi-
ronmental Protection Agency, Cincinnati, OH. 146 pp. (NTIS PB-287-
140).
Hallowell, J. 6., L. E. Vaaler, J. A. Gruklis, and C. H. Layer. 1976.
Assessment of Industrial Hazardous Waste Practices:'El ectroplating and
Metal Finishing Industries - Job Shops. SW-136c. U. S. Environmental
Protection Agency, Washington, DC. 190 pp. (NTIS PB-264-369).
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. McFaddin
and E. J. Daley. 1979. Recovery, Processing, and Utilization of Gas
from Sanitary Landfills. EPA-600/2-79-001. U. S. Environmental Protec-
tion Agency, Cincinnati, OH. 133 pp.
Hanranan, D. 1979. Hazardous Wastes: Current Problems and Near-Term Solu-
tions. Techno!. Rev. 82 (2):20-31.
Hildebrand, J. H. and R. L. Scott. 1950. The Solubility of Nonelectrolytes.
3rd ed. Rheinhold Publishing Corp. (Reprinted by Dover Publications,
NY, 1964.) 488 pp. ......
43
-------
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. U. S. Environmental Protection
Agency, Cincinnati, OH. 152 pp. (NTIS PB-282 443/1BE).
Leo, P. P., and J. Rossoff. 1978. Controlling S02 Emissions from Coal -
Fired Steam-Electric Generators: Solid Waste Impact. Volume II: Techni-
cal Discussion. EPA 600/7-78/044b. U. S. Environmental Protection
Aoency, Research Triangle Park, NC. 235 pp. (NTIS PB 281 100/85E).
McMahan, J. N., L. Cunningham, L,, Woodland, and D. Larnbros. 1975. Hazardous
Waste Generation, Treatment and Disposal in the Pharmaceutical Industry.
Contract No. 68-01-2684. U. S. Environmental Protection Agency, Washing-
ton, DC. 178 pp.
Metal Finishing Guidebook and Directory. 1979. Vol. 77, #13, Metals and
Plastics Publications, Inc., Hackensack, NJ.
National Solid Waste Management Association. 1981. Annual Survey of Land
Disposal Practices. Waste Age. 12(1): 65^74.
PEDCO. 1981. Mining Industry Solid Waste - An Interim Report. Office of
Solid Waste. U. S. Environmental Protection Agency, Cincinnati, OH. 93
PR.
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, DC. 268 pp.
Riley, J. E. 1974. Development DC ,-nent 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. U. S. Environmental Protection Agency, Washington, DC. 195
pp. (NTIS PB-238-609).
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.
WAPORA, Inc. 1975. Assessment of Industrial Hazardous Waste Practices, Paint
and Allied Products Industry, Contract Solvent Reclaiming Operations, and
Factory Application of Coatings. U. S. Environmental Protection Agency,
Washington, DC. 296 pp.
Wigh, R. J. 1979. Boone County Field Site. Interim Report, Test Cells 2A,
28, 2C, and 2D. EPA-600/2-79-058. U. S. Environmental Protection
Agency, Cincinnati, OH. 202 pp. (NTIS PB-299-689),,
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.
44
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CHAPTER 3
LINING MATERIALS AND LINING TECHNOLOGY
3.1 INTRODUCTION
The purpose of lining a waste disposal site is to prevent potentially pol-
luting constituents of the impounded waste from seeping from the site and
entering the groundwater or surface water system in the proximity of the
site. The pollutants, as discussed in Chapter 2, include organic and in-
organic materials, solids, liquids, gases, and bacteriological species. In
their performance liners function by two mechanisms:
a. They impede the flow of leachates and thereby limit the movement
of pollutants into the subsoil and thence into the groundwater.
This requires a liner material having low permeability.
b. They absorb or attenuate suspended or dissolved pollutants, whether
organic or inorganic, and reduce their concentrations so that
they fall within the ranges set by the EPA for groundwater. This
absorptive or attenuative capability is dependent largely upon the
chemical composition of the liner material and its mass.
Most liner materials function by bath mechanisms but to different degrees
depending on the type of liner material and the waste liquid and its con-
stituents. Membrane liners are the least permeable of the liner materials,
but have little capacity to absorb materials from the waste. They can absorb
organic material but, due to their small mass, their total absorption is
small. Soils can have a large capacity to absorb materials of different
types, but they are considerably more permeable than polymeric membranes.
However, the greater the thickness of a given soil, the lower the flux through
the liner. The choice of a particular liner material for a given site will
depend upon many factors which are discussed throughout this Technical Re-
source Document. In this chapter, the major candidate materials for use as
liners are discussed.
For the purpose of this Technical Resource Document, we consider a liner to be
a material constructed or fabricated by man. Such a definition includes not
only synthetic membranes and admixes but also soils and clays having low
permeability which are (1) either brought to a site or available on the site
and (2) remolde'd and/compacted to reduce permeability.
Liners can be classified in a variety of ways, such as construction method,
physical properties, permeability, composition, and type of service. These
45 1
-------
classifications are presented in more detail in Table 3-1. In this chapter,
the various types of liner materials are discussed in the following classes:
- Soils and clays.
- Admixed materials.
- Polymeric membranes.
- Sprayed-on liners.
- Soil sealants.
- Chemisorptive liners.
TABLE 3-1. CLASSIFICATIONS OF LINERS FOR WASTE DISPOSAL FACILITIES
A. BY CONSTRUCTION:
- Fabricated on site:
- Raw materials brought to site and liner constructed on site.
- Compacted soil.
- Mixed on site or brought to site mixed.
- Sprayed-on liner.
- Prefabricated:
- Drop-in polymeric membrane liner.
- Partially prefabricated:
- Panels brought to site and assembled on prepared site.
B. BY STRUCTURE:
- Rigid (some with structural strength):
- Soil.
- Soil cement.
- Concrete, including airblown concrete (shotcrete).
- Semi rigid:
- Asphalt concrete.
- Flexible (no structural strength):
- Polymeric membranes.
- Sprayed-on membranes.
C. BY MATERIALS AND METHOD OF APPLICATION:
- Compacted soils and clays.
- Admixes, e.g. asphalt concrete, soil cement.
- Polymeric membranes, e.g. rubber and plastic sheetings.
- Sprayed-on linings. , ...
- Soil sealants.
- Chemisorptive liners.
46
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For each type of lining material, characteristics and general features of the
liner and the advantages and disadvantages are discussed.
3.2 SOILS AND CLAYS
3.2.1 Introduction
Due to their general availability, soils should be considered the first
candidate material for the lining of a waste impoundment and disposal
facility. Based on engineering, environmental, and economic criteria, an
initial analysis should assess whether the native soil present at a site can
be used to produce an effective liner. If the result of such an analysis is
negative, other alternatives must then be explored.
A soil liner is the soil material which is native at or near the waste
disposal site and which has been properly treated, remolded and/or compacted
so that a flow-impeding layer of low permeabliity to wastes has been obtained.
Thus, low permeability and the retention of low permeability are, by far, the
most important characteristics of a soil-liner. No matter how low the perme-
ability is, a pollutant can still travel from the waste disposal site toward
the groundwater via liner and underlying soil. To attenuate this effect, the
soil liner has to possess the capacity of temporarily retaining the-polluting
species.
Both the low permeability and the high adsorption capacity are properties
often associated with the presence of soil fines. Thus, as a general rule,
one can state that the proportion of clay size particles (less than 2 urn) has
to be one of the most significant criteria in the selection of a soil to be
compacted as a soil liner. The reason a certain limiting value of clay
size particles cannot be categorically stated is, that both soil permeability
and adsorption capacity are dependent on other factors apart from the pro-
portion of fines. Among these, the gradation and the degree of weathering of
the nonclay fraction, and the physicochemical and mineralogical properties
of clay, are of considerable significance. Depending on these properties and
on the required saturated hydraulic conductivity, which in general will be
in the 10"9 to 10"° cm s"^ range, the acceptable proportion of fines in
a soil liner cannot be less than 25%.
In order to produce a soil liner that will function according to the design
specifications, it is imperative to have a good understanding of the clay
fraction. In a clay soil the hydromechanical behavior of the bulk soil
depends on clay surface physicochemical characteristics; since these are
determined by the clay mineral chemistry, the behavior of a clay soil can
be understood only if the chemistry and the mineralogy of the clay fraction
are carefully considered.
The compacted soil liner should be designed following a proper environmental
analysis. Criteria have to be sef forth and "the functionality of the soil
liner has to be assessed. If the environmental conditions have been analyzed
and understood, and the design complies with all environmental requirements,
the liner should function as desired.
47
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3.2.2 Clay Properties
In the previous section the need was stated to consider clay properties
relevant to the problem of constructing a clay-soil liner. Only an overall
view of essential clay characteristics is presented in the next two sections.
More detailed information on the properties of clays is available in some of
the classical monographs, such as Grim, 1962; Grim, 1968; Marshall, 1964;
Mitchell, 1976; Van Olphen, 1963; Yong and Warkentin, 1975.
3.2.2.1. Chemistry and mineralogy of clays
Table 3-2 presents some of the essential properties of kaolinite, illite
and montmorillonite (smectite group) clays. In superficial soils, very
seldom is the clay fraction totally dominated by only one of these three
constituents. Furthermore, whether the characteristics presented in Table 3-2
will be significantly imparted to the soil of which they are a part depends on
several other soil properties. The table shows the considerable difference
in swelling potential between the three mineral species most likely to
dominate the mineralogical composition of many soils. However, this is a
"micro" behavior. The degree to which the bulk soil will react to this
behavior depends on several factors among which the most prominent are:
the clay proportion in the soil, the surface area of the nonclay fraction,
and the geometry of the clay vis-a-vis the nonclay fraction (i.e. whether
the clay coats the sand and silt or is mainly concentrated between the larger
particles).
Among groups of clay minerals which are dominant in soils, the members of the
kaolinitic group are very likely to behave as though they possess a "unique"
structure, insensitive to the chan'ges in hydration condition and the character
of load application. The explanation for this behavior can be found in the
structure and in the average size of kaolinite particles. This mineral is
concentrated in the 0.5 to 2 pm range ("coarse" clay), which has a smaller
surface area compared to other clay minerals. Furthermore, unlike many other
clay mineral groups, the member:; of the kaolinitic group (1:1 minerals)
possess no internal cleavage, successive tetrahedron/octahedron assemblages
being linked by relatively strong hydrogen bonds. The lack of internal
surface enhances the inactivity of kaolinitic clay minerals. The kaolinitic
members are also chemically inactive because, unlike other minerals, they are
almost perfect minerals, i.e. they display almost no isomorphous substi-
tution. All of these facts make a kaolinitic clay quite invulnerable to
changes in moisture condition. The kaolinitic structure is relatively rigid
with no appreciable tendency to shrink or swell. Kaolinitic clay behaves, in
many respects, like a finely-ground silt material.
Illite is characterized by the presence of "fixed" potassium ions in a
twelve-fold coordination between two planes of oxygen atoms. The higher
charge of the crystal unit combined with the perfect fit of the potassium
ion in its cavity, promotes rigidity and impedes water penetration between
crystal layers; consequently, only a limited swelling occurs. A second very
important aspect of the presence of "fixed" or "nonexchangeable" potassium
between successive layers is that, despite its high negative charge, i.e. its
potentially high exchange capacity, the real cation exchange capacity (CEC) is
48
-------
TABLE 3-Z. TYPICAL VALUES FOR PROPERTIES OF KAOLINlTE, '.LUTE, AND MONTMORILLONITE*
^article dimensions, jn
Largest largest Lattice Charge
C
l.L UttKe) 0.3-4.0 Q.OS-^.u ... 0.74C 0
Z 1 lattice)
a-montmori 1 lonite (limited
e»oansion 2:1 lattice)
aansive 2.1 lattice)
.1-0.3 >0.003 ... 1. 00 1.3-1.59
ot easily «term1 naDle, 1Q-LOO 0.96-1.30" 3.65
ut sm«l ler tnan tne
igures for illite.
ut vt+\ Ur tnan tne
igures for 1 1 1 1te
Excnange
Surface area, T*/q n »qu
•ater Cation
I2a 1-VS
52-d2d 10-40
ca 7501 164-206a dO-150
ca 7SQ1 203-25Qd 30-150
capacity
v/100 q
Anton
s-za*-'
10-30*-'
10-30*
CNewnnain, 19S6, Srinoty jnO ^0011500, L9*6.
^Jonansen and Ounmnq, L9S9.
•Hoffman «t «l, 19^6.
rOH i«0«twj«nt.
IGrm et il . 1937.
"frequently, two nolecylar Uy«rs of *ater »itn 1.15-1.55 run.
]Van Jlonen, 1963.
only a fraction of the potential one. The real CEC of the illite is inter-
mediate between the CEC of kaolinite and that of smectite (montmorillonite).
Smectite (montmorillonite) has characteristically the smallest particle- size
of the three basic clay minerals. Typically the site of the negative charge
is in the inner octahedral layer in which partial isomorphous substitution
occurs; this generates a minimal cohesion between successive 2:1 layers,
resulting in a very receptive and chemically active structure. Smectite
(montmoril lonite) readily absorbs polar organics or positively- charged organic
groups or inorganic ions. It exhibits the greatest surface area, CEC, and
shrink-swell potential. In water, it can absorb on its interlayer surfaces
300% of its solid phase weight and consequently has the capacity for large
shrinkage if the water is displaced by other liquids that yield a lower
interlayer spacing.
Calcium montmorillonite adsorbs interlayer water to yield a stepwise increase
in basal spacing from 1 nm (oven dry state) to about 2 nm (Theng, 1979). At 2
nm, the Ca-montmori1lonite is fully expanded. With divalent cations such as
calcium or magnesium adsorbed to its surfaces, montmori1lonite resists
dispersion and remains flocculated. While the flocculated state usually
yields a higher permeability, its structure is more stable than the easily
dispersed sodium saturated montmorillonite.
Sodium montmorillonite adsorbs interlayer water to yield a basal spacing
from 1 nm (oven dry state) to over 5 nm (Theng, 1979). This increase in
spacing represents a thickness of 4 nm for water on each surface. While this
much interlayer expansion would at first appear advantageous for its ability
to reduce clay liner permeability, the expansion is reversible and hence
sodium montmorillonite is susceptible to shrinkage if it dries. Another
49
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problem with sodium-montmoril lonite is that when it is fully expanded, it is
susceptible to dispersion and internal erosion (see "Piping" in Chapter 4). A
dispersed clay that lacks structural strength could flow as a viscous fluid if
it is free to expand. This characteristic may cause problems such as loss of
strength in waste impoundment side walls.
The description of the most significant characteristics of these three mineral
species does not imply that all members of a particular clay mineral group
have the same characteristics and properties. Thus, for example, the typical
high swell/shrink behavior of the montmorillonite is explained in terms of the
location of the isomorphous substitution in the crystal, which is the octa-
hedral layer. However, there are members of the smectite group in which
aluminum is substituted for silicon in the tetrahedral layer and only a
limited tendency to volume change is to be expected.
The variability of properties in the smectite group is best revealed when
comparing montmoril1onite present in bentonite deposits located in geo-
graphically different regions. The bentonite is a rock found predominantly in
tertiary and upper cretaceous deposits and is believed to have been formed
from volcanic ash sedimented in marine environments. The smectites represent
the main mineral group found in this rock.
The bentonite, due to its unique prDperties, is commercially used as a thick-
ener in oil-well drilling fluids, a'5 cement slurries for oil-well casings, as
bonding agent in foundry sands and pelletizing of iron ores, as a sealant for
canal walls, a thickener in lubricating greases and fireproofing compositions,
in cosmetics, as a decolorizing agent, as a filler in ceramics, refractories
and paper coatings, as an asphalt modifier, as polishes and abrasives, as a
food additive, and as a catalyst support.
Most of the bentonite deposits that have been investigated contain Ca-satu-
rated montmoril lonite. A bentonite mined in Wyoming, the most investigated
of all bentonites, contains Na-montmori11onite. The montmori11onite in
Wyoming-type bentonite is a unique mineral as proven by the fact that the
saturation with sodium ions of an ordinary montmori11onite does not result in
the conversion to Wyoming montmori11onite (Grim, 1968). Some of the unique
characteristics of the mineral are related to its crystalline structure and
are probably a reflection of its unique origin.
In using the commercial bentonite for waste impoundment, the most important
characteristic to be considered is the nature of exchangeable cations in the
mineral and the extent of saturation with it. Only bentonite containing
Na-montmori1lonite should to be accepted as a liner material or as a component
in an admix liner, because of the close correlation between the permeability
of the clay and the exchangeable sodium percentage.
The permeability of three clays as' a function of exchangeable calcium and
sodium contents is shown in Figure 3-1. Yong and -Warkentin (1975) observed
that clays with divalent cations are, in general, more permeable than those
with monovalent cations- adsorbed onto interlayer surfaces. This effect is the
same in all clays but is most pronounced in smectite (montmori1lonite).
50
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100
100
Exchangeable Cation
Figure 3-1. Relative permeability values for three clays with variable
percentages of calcium and sodium on exchange sites (Yong and
Warkentin, 1975).
Quirk (1965) found that permeability of sodium saturated montmoril lonite
decreased when the concentration of NaCl in the percolating solution was
decreased. A similar clay saturated with calcium showed no appreciable
decrease in permeability with a decrease in the calcium concentration of the
percolating solution. Quirk and Schofield (1955) showed larger permeability
decreases with decreasing electrolyte concentration in the percolating solu-
tion for clays with higher percentages of sodium on the exchange sites.
Blackmore and Marshall (1965) found that increasing sodium chloride concen-
trations in a liquid passing through a film of sodium saturated montmoril-
lonite suppressed the double layer. The diminished double layer effect
inhibited swelling while it decreased interlayer spacing and permeability.
- 3.2.2.2 Attenuation Properties of Soil Liners
As indicated in
soil liner are
the introduction to this chapter, the two main functions of a
(1) to impede the flow percolating through it, and (2) to
51
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retain the polluting species of the waste effluent. The first will be given
priority and will be extensively discussed in subsequent chapters. The second
will be discussed briefly in this section.
The attenuation capacity of clays and clay-containing soils is mainly the
capacity of these materials to absorb ionic species stoichiotnetrical ly,
particularly the cations. The questions of why, how, to what extent, and how
fast these reactions occur have been thoroughly investigated in the field of
soil chemistry for cations such as Na, K, NH^, Ca, Mg, Ba, and a few others.
Very few investigations have been performed on the transport and retention of
ionic species that are relevant to the waste disposal problem. Furthermore,
the field conditions have not been properly simulated in experimental stu-
dies. The following points describe some of the limitations of the presently
available information and its use:
- The transport of solutes through soil liners is likely to occur as
unsaturated flow. Most of the experimental work performed on columns
was done as saturated flow.
- Often, column experiments are performed at unreasonably large hydraulic
gradients. It is unlikely that reducing the residence time of a
particular solute will result in data directly transferable to the
field, although the provisiDn is always made to assess the soil/solute
reaction as a function of the number of pore volumes (Fuller, 1978).
- Often, a polluting constituent is present in the percolate at a low
concentration beyond our capability to detect properly and monitor the
soil/solute interaction. At the present time, we lack the data in
this concentration range. It is questionable whether adsorption
isotherms carried out at relatively large concentrations can be
extrapolated in the low ranee of concentrations.
- It is probably impossible to simulate a waste effluent and its complex
chemistry. The results obtained in the laboratory with relatively
simple liquids will indicate only trends in the possible behavior of a
pollutant under a waste disposal site.
The attenuation capacity of soils for cationic and anionic chemical species,
e.g. Cd, Co, Hg, Ni, Pb, and As, Cr°+, Se, and V, seems to be, in a more
complex manner, associated with soil ion adsorption capacity. In a compre-
hensive study on the subject (Purer, 1978), no significant correlation was
found between the retention of these elements and the exchange capacity of 11
soils, in spite of the close relationship between retention and the proportion
of clays in these soils. Further studies are required to generate break-
through curves (C/Co vs distance or time) for polluting constituents and
potential contaminants.
These data are needed as input information for 'solving the mass transport-
dispersion equation including a sink-source term (Kirkham and Powers, 1972;
Freeze and Cherry, 1979).
52
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Modeling the functionality of soil/waste or soil/chemical species systems has
been done (Lowell, 1975; Fuller, 1978). Such an analysis requires an ac-
curate assessment of the particular interaction between the specific wastes
and soil under consideration.
Available experimental data have not generated the knowledge required to
quantify the multitude of possible interactions between soils (soil prop-
erties) and wastes (chemical species). When these data become available, the
designer of a soil liner should only identify relevant soil properties (clay
content, clay physicochemical and mineralogical characteristics, free iron
oxides, sparingly soluble salts, etc) and polluting species in the waste
likely to produce contamination. Accounting for the flux rates likely to
occur through the liner, the designer should then identify the types of
breakthrough curve expected during flow (Fuller, 1978). This information can
be used in the mass transport-dispersion equation to calculate the concentra-
tion of polluting species as a function of distance, time, and original
concentration at the boundary between the liner and the waste.
3.2.3 Engineering Characteristics of Clay Soils
In this section, the following four characteristics of soils are discussed:
- Atterberg limi ts.
- Compactibility.
- Volume changes.
- Permeability.
The significance of these characteristics to the problem of waste confinement
is emphasized.
3.2.3.1 Atterberg limits
The plastic and the liquid limits are essential tools in engineering work
for classifying and characterizing clay soils. This is reflected in the
emphasis on plasticity parameters in the classification of fine soils using
the Unified Soil Classification System (Appendix I). The consistency of a
given soil varies with moisture content, particularly with soils containing
larger proportions of clay.
The plastic limit is the soil moisture content just below which the soil
is friable and just above which the soil is plastic (it can be molded as a
paste which exhibits a permanent set). The liquid limit is the soil moisture
content just below which the soil is barely plastic and just above which the
soil flows. At the liquid limit, soil -behavior is a blend of plastic deforma-
tion (tends to cease deformation upon stress removal) and liquid flow (deforms
freely after stress removal).
The plasticity test generates results in terms of mechanical behavior deter-
mined largely by the chemical and mineralogical properties of the clay
in the soil.
53
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The "Atterberg Limits" is a test that helps in classifying the soil and,
consequently, weighs heavily in the decision-making process; it will help
determine if the waste disposal site is covered by a soil that can be used as
a soil liner. Soils that belong to the groups CL or CH should be considered
the most suitable. Probably the most favorable soils are those with a liquid
limit between 35 and 60, placed above the A-line in the PI vs LL chart of the
Unified Soil Classification (Appendix I).
The informative power of this test can be increased by coupling it with
knowledge of the clay content, i.e. the percentage of particles less than
2 urn in diameter. The concept of "activity", introduced by Skempton (1953),
normalizes the plastic effect per unit weight of clay. Since this has been
found to be characteristic of any particular clay (Skempton, 1953) depending
on the type of clay (Mitchell, 1976), quick information regarding the type of
clay in the soil can be obtained without resorting to x-ray analysis or other
more quantitative mineralogical analyses.
The usefulness of plastic and liquid limits in geotechnical work can hardly be
overemphasized because the limits are highly correlated with the quality and
quantity of the clay fraction, which in turn control geotechnical properties
in clay soils. Thus, compressive and shear characteristics are greatly
affected by the clay content. Consolidation is a behavior strictly associated
with clay soils. Shrink and swell characteristics have been correlated with
Atterberg limits. Finally, soil flow properties are affected by the clay
content. In many instances, knowledge of the Atterberg limits of a given
soil leads to a fair estimate of the particular geotechnical behavior of
interest.
The Atterberg limits are the result of a reaction between the clay phase
of a soil and water. Consequently, the composition of both soil and water has
an effect on the' plastic behavio~ of the soil; thus, soil plasticity is a
system property rather than a soil property, an idea suggested by Goldschmidt
as early as 1926 (Goldschmidt, 1S26). Subsequent studies (Warkentin, 1961)
indicated that a Na-montmori1lonite .had a liquid limit almost three times
larger when water was the liquid used rath.er than a molar solution of NaCl.
It has been also shown that the Flow Index (the negative slope of water
content vs logarithm of number of blows in Casagrande's device) depends upon'
the nature of clay minerals and upon electrolyte concentration (Yong and
Warkentin, 1975, p. 64).
In our studies on the subject, we used soils containing between 25% and 45%
clay size particles (<2 ym). Solutions of NaCl and CaClg in water were used
as the soil mixing liquid. A combination of two levels of salt concentration,
2 and 50 g L"^, and two levels of sodium adsorption ratio" (SAR), 2 and 20
(mmoles/L)r/2 yielded results which reinforced the idea that fluid chemistry
has a significant influence on the li.quid lim.it.. The following conclusions
were reached:
1. The higher the proportion of fines in a soil, the larger the effect
of liquid chemistry.
54
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2. The value of the liquid limit is more affected by liquid chemistry
than is the flow index.
3. In a soil containing montmori 1 lonite, both the SAR and the total
salt concentration (TSC) significantly affected plastic charac-
teristics. The higher the SAR and the lower the TSC, the larger
the 1iquid 1imit.
4. In a predominantly kaolinitic soil, the lower the TSC, the higher
the 1iquid 1imit.
In this example, only two liquid-phase characteristics were investigated.
It is, however, to be expected that other characteristics like pH, abundance
of non-native ionic species and chelating agents, density, viscosity, dipole
moment, dielectric constant, etc, may have a significant impact on the fabric
geometry of a soil and thus on the limits and on relevant geotechnical charac-
teristics.
As indicated in the previous paragraph, the effects of industrial waste
effluents generally differ from those of water; therefore, the determination
of the limits using ASTM D423-66, "Liquid Limit of Soils", will not suffice as
it calls for the use of distilled water. In most geotechnical projects, the
use of water in this test is acceptable because it simulates the environment
in which the soil will be used. However, many industrial waste disposal
facilities will generate aggressive leachates and, as part of the ASTM pro-
cedure, the liquid limit should be tested using a simulated waste effluent.
By comparing these two liquid limit values, the sensitivity of the soil vs
liquid characteristics will be indicated. This procedure can reveal, at an
early stage of site investigation, the general compatibility between the soil
being considered as a liner and the specific waste. If the determination of
the liquid limit using the waste effluent yields a drastic change in the limit
compared to that using water, the permeability of the soil should be thorough-
ly studied with the particular waste effluent. On the other hand, if the
limit using the two liquids is the same, the conclusion can be drawn that a
limited number of permeability determinations using the waste effluent should
suffice.
3.2.3.2 Compactibility
The practice of soil compaction is a routinely used procedure of site im-
provement. It is well known that, generally, the higher the density of a
soil, the higher its strength, and thus the soil is better suited as a geo-
technical material.
Soil compaction has the same beneficial effect on soil permeability provided
all conditions are held constant, the higher the density of a soil, the
lower its permeability. This relationship seems.to be, however, more complex
than the density/strength relationship, because upon densification "all
conditions" cannot be held constant. In particular, soil fabric is altered
and since'soil flow characteristics are very sensitive to structural changes,
the' relationship between soil density and permeability is not a simple one.
55
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Some of the interactions between several independent variables which affect
the density-permeablity relationship are discussed in Chapter 5.
The fundamental aspects of soil compaction were established almost a half-
century ago by R. R. Proctor (Burmister, 1964). Thus, it was found that any
soil has a characteristic laboratory density/moisture relationship if com-
paction conditions are held constant. This relationship defines a unique
density value (maximum density) aid a corresponding moisture (optimum moisture
content), which are essential parameters for design considerations.
It is well recognized that an increase of compactive energy increases the
characteristic maximum density and decreases the optimum moisture value
(Felt, 1965). Similarly, it was found that a time factor is involved in the
compaction process. The longer the compactive effort is applied, the higher
the density value, which is a logical consequence of the fact that volume
reduction upon compaction is a progressive microfailure mechanism in which
during load application the magnitude of average stress per bond increases
continuously and stronger bonds become vulnerable to breakage.
The laboratory or field soil layer thickness, upon which the compactive
effort is applied, is significant in terms of the overall bulk sample or site
density. The smaller the layer thickness, the higher the density achieved.
This fact is a result of stress distribution below the compactive implement.
As a general rule, the effect of soil mechanical composition on the shape
and position of the moisture-density relationship is as follows:
a. The more granular and the better graded the soil, the higher the
maximum density and, consequently, the lower the optimum moisture.
b. The finer the soil (the more clayey it is), the less defined the
maximum density and the flatter the curve on the dry-of-optimum
side. This is because the effect of equal increments of water added
to a soil dry-of-optimum depends on the concentration of fines in the
soil. The larger the proportion of fines, the smaller the moisture
content of the clay unit when the same amount' of water per unit of
soil is added dry-of-optimum. Since the clay fraction is a binder of
larger soil particles and since clay strength is related to its
moisture content (effective stress concept in unsaturated soils), the
more clay in the soil, the "drier" the clay fraction at the same
soil moisture content and thus the more the bulk sample will resist
densification.
Considerable effort was directed toward correlating field and laboratory
compaction .characteristics, particularly following the introduction of the
modified AASHTO compaction test procedure (McDowell, 1946).
Uniformity of moisture content of the field "soil, that is to be compacted
is important, particularly when light rollers are being used. Heavy rollers
seem to be more effective in compacting soil in a field of variable moisture
content (Burmister, 1964).
56
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For reasons which will be explained in detail in Section 3.2.3.4, the com-
paction operation in the field has to be conducted at a moisture content
as high as possible. However, when the compaction is performed in the field
at a moisture content over the optimum, operation limitations restrict using
heavy rollers; in this case, the desired density has to be achieved by in-
creasing the number of passes over the compacting layer. Some experimental
results have also shown that increasing the foot pressure used and decreasing
the lift in the same proportion result in equally dense soils (Sowers and
Gulliver, 1955).
In Chapter 5, we will discuss the methodology of designing a soil liner,
indicating the laboratory information needed to formulate the design criteria.
At this stage, we want to reiterate that most of the knowledge available in
the soil mechanics literature on soil compaction is basically applicable for
the situation when a waste impoundment soil liner is being prepared. However,
the designer should be aware of the particularities of such a "hydraulic"
structure, among which the character of the liquid that percolates through
the liner is the most prominent. Another complicating factor is the complex
relationship between soil permeability and density, even when water is the
percolating 1iquid.
3.2.3.3 Volume changes
Volume changes that may occur following compaction of the soil liner should be
estimated because a change in bulk density will result in a change in trans-
port properties. If a soil is marginal in terms of its potential for gene-
rating a particular "as compacted" K value, and if it has a high swell/shrink
tendency, it will likely be rejected as a liner candidate.
In general, volume changes have a detrimental effect upon soil permeability.
However, there are conditions and circumstances when the effect may be bene-
ficial, i.e. when a sealing of the soil occurs as a result of the high volume
changes of the particular soil. Thus, volume change tendencies should be
known because, if they alter the designed properties to the extent that an
opening of the structure is generated, a progressive failure is initiated.
Failure mechanism as it relates to swell and shrink is explained in Chapter
4.
If the moisture content of the soil element under consideration will change
compared to the "as-compacted" state, then swelling or shrinking may occur
provided the necessary conditions are present. According to Nayak and
Christensen (1971), the following factors determine the intensity of volume
change manifestation:
- Type and amount of clay mineral.
- Nature of pore liquid.
- Initial placement condition, e.g. structure and density.
- Stress history.
- Temperature. - -
- Volume change permitted during swelling pressure measurements.
- Shape, size, and thickness of the sample.
- Time.
57
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In this section, we present a discussion on the first three of these factors
since they are most significant when assessing the susceptibility to volume
change of a soil liner retaining waste leachate.
The characteristics and concentration of the clay component have a dominating
effect on volume change behavior to the extent that quite often we associate
swelling and shrinking soils with the term "clay" soils. This is a conse-
quence mainly of three characteristics of clay particles compared to larger
silt and sand size particles:
1. Water adsorption and retention is a surface phenomenon. The greater
the surface of the soil particles, the more water is retained.
Thus, the higher the clay concentration in a sample, the greater the
surface and the larger tie amount of water associated with the unit
mass of the soil sample.
2. Unlike bulkier soil particles, the clay particles are charged,
usually carrying a negative charge. This results in a preferential
retention in the immediate vicinity of the clay surface of cations
which are hydrated in natural environments.
3. In the case of many widespread clay mineral species, e.g. members
of the smectite group, the retention of water is not a surface
phenomenon in the sense that water penetrates 1nside the particle.
Thus, it is an imbibition mechanism which results in an association
of water beyond and over the amount proportional to the clay external
surface.
The nature and characteristics of the liquid interacting with the clay
have a profound effect on specific adsorption. This has long been known
for the condition when water is the liquid phase. The chemical composition
of the solution and its total electrolyte concentration perturb the config-
uration of the "exchangeable cations" and thus control the interlayer volume
for liquid penetration. The swell and shrink characteristics of the clay are
highly controlled by the composition of the liquid.
The condition in which the liquid phase contacting the soil is n'ot water
but a different organic compound (less investigated because it does not
constitute a natural environment) is of great significance for soil liners.
In Chapter 4, examples are given to reveal the drastic effect some organic
compounds have upon volume change characteristics of different clays. Some
organics interact with clays so specifically that they represent standard
reagents for clay mineral identification. Thus, solvation with glycerol of a
Mg-saturated clay sample containing montmorillonite, vermiculite, and chlo-
rite, with an original basal (001) diffraction spacing of 1.45 nm, allows
the identification of montmorillonite because this is the only component which
increases its treated basal spacing to exactly 1.8 rim.
Basic information on liquid chemistry/c-lay swell.-interaction can be found in
the two monographs on. clays by Grim (1962, 1968) and in the two excellent
volumes on soil behavior written by Yong and Warkentin (1975) and Mitchell
(1976).
58
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The third significant factor which has a considerable impact on volume
change behavior of soils containing an appreciable amount of clay (e.g. over
20%) is the sample preparation or, for the field Condition, the placement and
compaction characteristics. Thus, the structural" characteristics of the clay
generated as a result of a particular compaction procedure are very signif-
icant in terms of subsequent volume change behavior. If two samples of the
same soil are compacted at the same moisture content using two different
compacting procedures (e.g. static vs kneading), it is likely that two dif-
ferent structures will be generated. This should be reflected by the pore-
water pressures measured on the as-compacted specimens. Normally, this value
should be -smaller for the statically-compacted sample (larger negative value).
This means that the statically-compacted specimen should behave as being drier
and thus should subsequently absorb more water, if available, and swell more.
As a general rule, however, the differences in structure generated in the
dry-side-of-optimum, due to the different methods of compaction, have a
minimal effect upon shrink/swell characteristics. The same is not true on the
wet side; the statically compacted soil (with a more flocculated structure)
swells more than the sample compacted with a kneading compactor. Day (1955)
showed a decrease in soil suction upon shear when, presumably, the soil
particles were in a less flocculated state in comoarison to the situation "at
rest", when the particles tended to have a more flocculated arrangement.
A revealing graphic representation of the tendency of compacted soil to
swell was presented by Holtz and Gibbs (1956) and is reproduced in Figure 3-2
These authors were able to show that (Seed et al , 1962):
a. As a general trend, the lower the moisture content and the higher the
density, the higher the swell potential.
b. An increase in molding water content at a given density causes
a decrease in swelling pressure and swell.
c. An increase in density at low moisture content causes an increase
in swell. An increase in density at high moisture content does
not alter drastically the swell characteristics.
Graphs like the one presented in Figure 3-2 are very useful. However, they
refer to the bulk swell behavior of the sample. When the strength or settle-
ment characteristics of a soil are of concern, information similar to that
presented in Figure 3-2 is useful, unless the compacted structure is meta-
stable. However, for assessing the effect of swell on liquid transmission
characteristics, the internal swell behavior is particularly important, even
when the bulk sample does not change its volume. Volume change as a failure
mechanism will be discussed in Chapter 4.
3.2.3.4 Permeability
Soil permeability, K, is the rate of movement of a unit volume of fluid per
unit cross-sectional area perpendicular to the flow direction normalized per
unit gradient. In geotechnical work, when water is the fluid under consider-
ation, the permeability is specifically referred to as hydraulic conductivity.
59
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Figure 3-2. Isoswell lines on moisture-density graph;
expansive clays under extremely dry and
dense conditions (Holtz and Gibbs, 1956).
Soil permeability is a measure of the ability of the soil to transmit a
particular liquid and is one of the most important geotechnical charac-
teristics, particularly in the case of clay soils. The rate of consol-
idation and settlement and, thus, the stability of an earth structure depends
on soil permeability. In the case of a heterogeneous soil body, the rate of
water movement in one part of the body may or may not change the pore-water
pressure in another part of the body and, thus, again the stability of the
earth structure depends on soil permeability. Finally, when a water-retaining
earth structure is constructed, the amount of water lost through seepage is
important; in this case, the hydraulic conductivity has a direct signifi-
cance.
Soil permeability is determined using Darcy's- relationship:
where:
J is the volume of liquid passing through a unit cross-sectional
area of soil per unit time, and
60
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vH is the hydraulic gradient, i.e. the rate of change of hydraulic
head in the direction of flow.
When H is expressed as "weight hydraulic potential" (units of length, L) and
J as volume divided by unit area times unit time (units of rate, LT'1), the
permeability is expressed in the c.g.s. system as cm s"1.
Darcy's law is a useful relationship which has been widely used to determine
K. Its simplicity reflects a well-proven fact, namely, that among all factors
determining the flux, J, the magnitude of the gradient is so overwhelming in
its significance that it masks the importance of other factors.
The main feature of this relationship, the linearity between gradient and
flux, i.e. the constancy of K, is well documented for most soils. The vali-
dity of Darcy's Law has been questioned for some clay soils. Thus, in highly
compacted and very fine clays, the physical properties of a large proportion
of the pore liquid may be altered due to the proximity between the liquid
and the soil matrix. Keeping the gradient constant but increasing the pore-
water pressure while the soil element is confined (constant void ratio),
relaxes the soil structure and increases the proportion of water affected by
the matrix proximity, and thus its average viscosity. The result is a soil
structure displaying a lower hydraulic conductivity.
A more drastic effect in changing the K value is obtained with some clay
soils when the gradient is increased to the extent that it induces total
separation of clay particles and causes migration of colloidal clay, which
subsequently plugs some of the pores.
In spite of -its limitations, Darcy's Law is still the main relation used to
describe the water flow in soils, particularly tor rigid soil structures, i.e.
those which are neither affected by the magnitude of the pore-water pressure
and the gradient, nor by osmotic and swelling effects. In qualitative terms,
•this relation will always be accepted, since the larger the hydraulic gra-
dient, the larger the resulting flux.
Because K depends on properties of both components, soil and liquid, the
intrinsic soil/flow properties can be identified by taking into account the
viscosity and density characteristics of the liquid. The resulting parameter
was called "intrinsic permeability" and the corresponding units in the c.g.s.
system are cm^. in this case, the liquid viscosity normalizes the resistance
to flow due to the liquid cohesiveness, while the liquid density normalizes
the effect of gravity on liquid flow. In principle, the use of intrinsic
permeability permits comparison of K values of several soil specimens of the
same soil, when permeated by different fluids.
In the case of lined waste disposal facilities, the soil liner may be con-
tacted by liquids of exotic chemical compositions. In this case, the kine-
matic viscosity correction which is operated on K to produce the intrinsic
permeability, is a minor improvement...
The primary goal of constructing a soil blanket of low permeability is carried
out in the field by soil compaction. .Through this operation a dense soil
61 i
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material is obtained with a lower void ratio. According to both Taylor-
Poisseuille and Kozeny-Carman relationships (Lambe and Whitman, 1979), K
is proportional to e3 (1+e) where e is the void ratio. This relation-
ship has not been quantitatively verified for fine soils.
The reduction of the void ratio upon compaction promotes two changes in the
soil: a decrease of the effective area available for flow (effective pore area
being measured perpendicular to the flow direction), and a decrease of the
median pore size value. The latter decrease is important because, according
to the capillary model, the flux (LT'1) is proportional to the second power
of the radius,. Thus, a reduction in the void ratio should result in a
considerable reduction of permeability, K.
An important consequence of the K-e function is that, as soils are particulate
media and K is always measured ort specimens for which the sample size is much
greater than average particle size, K will always be positive since the
condition e=0 contradicts the definition of a soil as a porous medium.
Consequently, truly impermeable soils (K=0) do not exist.
Most undisturbed soils Jiave permeabilities to water in the range of
10"' cm s"1 to 10~3 cm s . Intrinsic soil characteristics as well as nat-
urally occurring environmental conditions play a tremendous role in the
resulting broad range of permeabilities encountered in nature. If one looks
over the whole range of permeability values of undisturbed soil, the particle
size characteristics seem to be the most relevant; soils with more than 25-30%
clay size particles are concentrated in the lower range of permeabilities,
i.e. 10"' cm s~* to 10"^ cm s . If, however, one tries to correlate K with
the percentage of clay size particles over this latter narrow range of permea-
bilities, the relation between particle size and permeability becomes less
significant, i.e. other factors become relatively more significant in their
effect upon flow properties. The types of clay minerals present in the clay
fraction and the particle size distribution in the less than 2 urn fraction
play a very important role. 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 typi.cal soil aggregate
are factors that: effect profoundly soil-water flow characteristics; they can
alter the K value by as much as two orders of magnitude for otherwise ap-
parently similar soils. Since this can make the difference between using or
not using a particular soil as A liner, the site designer should obtain
pertinent information regarding physicochemical and mineralogical properties
of the clay in the soil.
The physicochemical behavior of a clay soil has such an overwhelming effect
upon soil permeability because of the dependence of soil clay structure on
physicochemical properties and the effect of the structure on permeability-.
If a soil clay fraction has a fixed structure, totally insensitive to changes
in hydration conditions and the way in which stresses are applied, then the K
vs w (water content) function would oe..a mirror: image of the y (density) vs w
function with the lowest permeability corresponding to the maximum density,
on the y vs w graph. Physicochemical factors have a drastic effect on clays,
particularly in the case of montmorillonite clays; they have a very sensitive
62
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structure and the permeability of a montmorillonite soil is far from being a
simple function of density.
Lambe (1958) showed that the permeability of a clay compacted dry-of-optimum
is much greater than that compacted on the wet side of the optimum. He also
concluded that the higher the compactive effort, the smaller the difference
between the ranges of permeabilities obtained on both sides of the optimum.
Clay compacted dry-of-optimum was found to have an "open", flocculated struc-
ture, while the wet-of-optimum clay tends to have a dispersed structure. This
effect determines the flow properties to such an extent that little is left
of the general belief that soil permeability and density are inversely
related. Lambe (1958) also noted that on the dry-of-optimum side, a thres-
hold pressure appears to exist beyond which the clay structure tends to
reproduce the structure of the "wet"-clay, i.e. to orient its particles
parallel to a preferred plane.
Some of these conclusions were carefully investigated in the 1960s by
Mitchell, et al (1965). In carrying out the investigation on a silty-clay
for which some of its mechanical properties were well documented, Seed and
Chan (1959) Mitchell et al (1965) confirmed the above conclusions and simul-
taneously revealed new effects. Thus, combining different compactive efforts
with d.i f ferent moisture contents to produce a unique, high density soil. (108
Ib ft"3 or 1.732 g cm"3), the permeability showed a slight increase with
the water content, on the dry side of optimum.
The effects of the compaction procedure were also investigated. When samples
were compacted by kneading compaction using the same compactive effort at
different combi nations of w and y, the slight effect of K increase with
density and moisture content in the dry-of-optimum range was still present;
but when the experiment was repeated with a different soil (over a more narrow
range of moisture content) the effect was not present, i.e. samples prepared
dry-of-optimum indicated a "normal" drop of permeability with an increase in
density.
Mitchell et al (1965) indicated that, when samples are compacted at a moisture
content below the optimum moisture, the K vs w function depends on so many
factors that, if precise information is needed, testing of the soil simulating
the field condition is the only alternative. Further increase in moisture
content beyond the optimum moisture resulted in a tremendous drop in K-value.
Furthermore, the results presented by Mitchell et al (1965) indicate that the
choice and use of a particular compacting effort is significant to the K-
value, particularly on the wet side of optimum. Using a very high moisture
content and compacting their silty-clay soil specimens using a kneading
compactor at the same void ratio, but using different compactive efforts, the
authors obtained a large range of K-values (over two orders of magnitude).
The conclusion is that, by compacting the soil at a very high moisture
content, the permeability can be significantly decreased by structural
arrangements of soil (clay) particles rather than diminishing the total void
space of the soil.
63
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The picture presented above refers to laboratory soil specimens compacted with
a kneading compactor, which better resembles the compaction of soils in the
field compared to static compaction (Lambe and Whitman, 1979). It has been
conclusively shown that particle preferential orientation and consequently
reduction of permeability upon compaction is more prominent in samples which
are compacted using a kneading compactor rather than impact, vibratory, or
static compaction (Seed and Chan, 1959; Mitchell et al, 1965).
Mitchell (1956) pointed out that clays, and presumably clay soils, are quite
different in their behavior upon remolding. In general, clay deposits which
are formed in marine or brackish environments are quite efficiently remolded,
i.e. a preferred orientation upon remolding can be achieved; this conclusion
seems to be particularly true for clays which have been precomoressed in
nature at very low stresses, e.g. the Scandinavian sensitive cl-.-s. Clay
deposits which have been sedimented in fresh waters and have been highly
precompressed, e.g. the Texas and New Orleans clays investigated by Mitchell,
could not be efficiently remolded since they already had an oriented structure
in their undisturbed state. Consequently, in establishing the technology to
be used for producing a soil liner, the designer should have information on
both the natural preconsolidation pressure of the soil and the conditions at
formation or deposition of the so-1.
The sensitivity of a soil is the ratio of the strength of the undisturbed soil
to that of the soil after remolding. Seed and Chan (1959) have indicated
that a simple test for revealing a sensitive structure is to compare the
undrained stress-strain characteristics of an undisturbed soil sample with
those of a sample remolded wet-of-optimum (Mitchell,. 1964). Because, in the
case of a soil liner, the permeability is the property to be considered and
since soil flow properties are at least as much structure sensitive as
strength properties are, the permeability rather than the strength should
be determined on undisturbed and remolded samples. Static and kneading
compaction procedures should be used in parallel to evaluate the effect of
void ratio and to identify the eventual effect a particular structure might
have on permeabilty.
The following conclusions should be considered when clay soils are compacted
to produce the lowest possible permeability:
a. The lowest permeabi1itias correspond, as a general rule, to the
condition when the soil is compacted wet-of-optimum moisture.
b. The-sensitivity of a soil structure unit is ascertained by increas-
ing the available water and the available compactive effort and
measuring the decrease in permeability, The testing program should
should reveal the relative significance of :hese two factors and
lead to the optimization of field compaction; the investigation
should identify the relative effects upon permeability of structural
vs density changes when the soil is being compacted.
c. Compactive implements which promote shear deformation of soil will
generate a better oriented structure and consequently help obtain a
soil blanket with a low permeability.
,64
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d. The higher the moisture content during compaction, the more criti-
cally important is the density obtained, e.g. a small decrease in
density (1%) may result in a permeability increase of one order
of magnitude.
The subject of soil permeability will be discussed further in Chapter 4 and
5.
Chapter 4 will present more detailed information on the interaction between
liquid chemistry, clay physicochemical and mineralogical properties, and
permeability. The discussion will be made i'n the context of soil liner
failure, i.e. an increase in permeability beyond the designed value.
•Chapter 5 will present the information required to design a soil liner, the
use of this information, and the permeability values to be reached in dif-
ferent circumstances.
3.3 ADMIXED LINING MATERIALS
3.3.1 Introduction'
A variety of admixed or formed-in-pl ace liners have been successfully used in
the impoundment and conveyance of water. These linings include asphalt
concrete, soil cement, and soil asphalt, a.l 1 of which are hard-surface
materials. The amount of experience in the use of some of the admixes in the
lining of sanitary landfills and the lining of impoundments of brine is
limited. Materials of this type have undergone exposure testing in contact
with municipal solid waste leachate (Haxo and White, 1976; Haxo et al, 1982)
in one EPA research project, and are undergoing limited exposure testing in a
second project with hazardous wastes (Haxo et al, 1977). In this section
the following types of admixes are discussed: hydraulic asphalt concrete,
soil cement, and soil -asphalt. Bentonite clay >s also discussed in this
section, as it is usually a processed product whith is spread and mixed into
on-site soil, and thus can be considered an admixed material.
3.3.2 Hydraulic Asphalt Concrete (HAC)
Hydraulic asphalt concretes, used as liners for hydraulic structures and
waste disposal facilities, are controlled hot mixtures of asphalt cement and
high quality mineral aggregate, compacted into a uniform dense mass. They
are similar to highway paving asphalt concrete but have a higher percentage
of mineral fillers and a higher percentage (usually 6.5 to 9.5) of asphalt
cement. The asphalt used in hydraulic asphalt cement is usually a hard
grade, such as 40-50 or 60-70 penetration grade. These harder asphalts are
better suited as liners than softer paving asphalt (Asphalt Institute,
1976).
A major factor in the design of a hydraulic asphalt mix for use as a liner to
confine wastes is the selection of an aggregate that is compatible with the
waste. For example, aggregate containing carbonates must be avoided in HAC
liners for acidic wastes.
65
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Hydraulic asphalt concrete can be compacted to Have a permeability coeffi-
cient less than 1 x 10"' cm s"1. It is resistant to the destructive wave|
action of water, light vehicular traffic, and effects of weather extremes"
(temperature). Such asphalt concrete is stable on side slopes, resisting
slip and creep, and retains enough flexibility to conform to slight defor-
mations of the subgrade and avoid rupture from low level seismic activity.
Asphalt concrete liners may be placed with conventional paving equipment and
compacted to the required thickness (Asphalt Institute, 1966).
Styron and Fry (1979) used 11 percent asphalt in a two-inch asphalt concrete
liner to obtain the necessary permeability. Haxo et al (1982) used a nine
percent asphalt concrete, but after one year of exposure to leachate from a
simulated landfill, determined that due to potential inhomogeneities in the
admixed materials, resulting from inadequate mixing or compaction, a liner
thickness greater than four inches may be necessary to contain wastes (Table
3-3). The HAC liner examined after 56 months of exposure was in good condi-
tion; properties had changed very little since the first specimen was ex-
amined at one year of exposure. A study by Southern California Edison showed
that an optimal compacted thickness, for a pond holding primarily water, was
two layers of two inches each for a total thickness of four inches (Hinkle,
1976).
The quality of the finished liner depends on the compaction during placement
(Bureau of Reclamation, 1963, p 40). The liner should be compacted to at
least 97% of .the density obtained by the Marshall Method (Asphalt Institute,
1976) or less than 4% voids (Asphalt Institute, 1981). Hinkle (1976) found
that a voids content less than 2.5% produced a permeability of less than 0.001
ft/yr (1 x 10"9 cm s ), as shown in Table 3-4. Samples containing 8.5%
asphalt at 97% compaction, in a pressurized permeameter, showed no observable
flow (Hinkle, 1976).
Before placement of the liner, the subgrade should be properly prepared. It
should not have side slopes greater than 2:1 and preferably no greater than
3:1 (Asphalt Institute, 1966). The soil should be treated with a soil
sterilant to prevent puncture of the liner by weeds and roots (Asphalt
Institute, 1966). Mixtures of sodium chlorate and borates are examples of
such soil sterilants (Bureau of Reclamation, 1963).
Asphalt has been used for centuries as a water resistant material. More
recent usage has shown that asphalt materials also are resistant to acids,
bases, inorganic salts (to a 30% concentration) and to some organic compounds
found in industrial wastes (Asphalt Institute, 1976). Asphalts are generally
not resistant to organic solvents, and chemicals, particularly hydrocarbons in
which they are partially or wholly soluble. Consequently, asphalts are not
effective liners for disposal sites containing petroleum derived wastes or
petroleum solvating compounds such as oils, fats, aromatic solvents, or
hydrogen halide vapors. Asphalt does show good resistance to inorganic
chemicals and low permeability to corrosive "gases such as hydrogen sulfide
and sulfur dioxide.
66
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3.3.3 Soil Cement
Soil cement is a compacted mixture of Portland cement, water, and selected
in-place soils. The result is a low strength Portland cement concrete with
greater stability than natural soil. The permeability of this mixture varies
with the type of soil; a more granular soil produces a more permeable soil
cement. A fine-grained soil produces a soil cement with a permeability
coefficient of about 10~° cm s"1 (Stewart, 1978). To date, there have been
few studies performed to design a soil cement with very low permeabilities
(less than 10"° cm s~*), as opposed to mixes designed for high compressive
strength. To reduce permeability of soil cement, coatin.gs such as epoxy
asphalt and epoxy coal-tar have been used.
Any soil, except organic soil, with less than 50% silt and clay is suitable
for soil cement. However, a well-graded soil with a maximum size of 0.75
inch and a maximum silt and clay content of 35% is preferable (Bureau of
Reclamation, 1963). A high clay content impairs the ability to form a
homogeneous cemented material thus reducing the efficiency of producing an
impermeable layer. Three criteria must be considered for soil cement liners:
cement content, moisture content, and the degree of compaction. The optimum
moisture and cement contents are determined by laboratory testing. The soil
optimum moisture is that which results in maximum density of the compacted
cement. Laboratory samples should be tested in wet-dry and freeze-thaw cycle
tests (ASTM D559 and ASTM D560) to determine the optimum cement content.
The aging and weathering characteristics of soil cements are good, especially
tfrose associated with wet-dry, freeze-thaw cycles. Some degradation has been
noted when this substance is exposed to highly acidic environments (Stewart,
1978), but soil cements can resist moderate amounts of alkali, organic
matter, and inorganic salts. One of the main deficiencies of soil cement as
a liner material is its tendency to crack and shrink on drying.
3.3.4 Soil Asphalt
Soil asphalt is a mixture of available on-site soil, usually low plasticity,
and liquid asphalt. A silty, gravelly soil with 10-25% silty fines is the
preferred soil type. The permeability of soil asphalt after compaction
varies with the percent compaction and the percent asphalt. A high void
content (3-10%) soil asphalt has a measurable permeability. Soil asphalts
containing cutback asphalt are not recommended as lining materials. Soil
asphalt made with asphalt emulsion is not sufficiently impermeable and
requires a waterproof seal such as a hydrocarbon resistant or bituminous seal
(Asphalt Institute, 1976).
3.3.5 Bentonite-Soil Mixtures
3.3.5.1 Types of bentonite
Bentonite is a colloidal clay compos.ed chiefly-of the clay mineral montmor-
illonite which was briefly discussed separately in the soils part of this
chapter (Section 3.2.2.1) There are two major varieties of bentonite: (1)
67
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sodium bentonite, which has a high swelling capacity in water, and (2)
calcium bentonite which has a negligible swelling capacity. Because of its
high swelling capacity, sodium bentonite is used as a sealant or a lining
material for water storage and conveyance. Polymer modifications of ben-
tonite have been developed which have improved resistance to saline water.
Bentonite is commercially available in bags or in bulk as a fine powder or as
granules, when used as a lining material, it is either applied directly, or
mixed into sand or the top layer of soil and compacted. In either case, the
layer containing bentonite is generally covered with a protective soil
cover. Slurry trenches, filled with soi1-bentonite slurry, are used to
control lateral movement of water or liquid wastes. Compacted soil-bentonite
or sand bentonite liners are usually 4 to 6 inches thick. A limited exposure
test of a compacted sand-polymer modified-bentonite mixture is included in
an EPA test program (Haxo et al, 1977).
3.3.5.2 Methods for evaluating bentonite mixtures
Bentonite content, moisture content and degree of compaction are the princi-
pal factors which determine the initial permeability of a soil-bentonite or
sand-bentonite liner. Permeability over a long-term period of exposure is
affected by ion exchange between the bentonite and components of the soil or
the waste being impounded, or by absorption of organic components of the
waste. Exchange of the sodium ions for calcium or aluminum, for example,
converts the sodium bentonite to a lower-swelling material, less effective as
a sealant than native clays. High concentrations of sodium in the water also
inhibit swelling, due to "ionic crowding" (Hughes, 1977). Initial saturation
of the bentonite with uncontaminated water minimizes the above effects, but
the improvement may not be permanent.
Tests of effectivness of bentonite liners for containing wastes are neces-
sarily very long-term; as short-term tests do not allow sufficient time for
displacement of the pore water by waste. According to Hughes (1977), a pore
volume displacement (PVD) of 2.0 is insufficent for definitive analysis of
the contaminant-resistant capability of a bentonite, and he suggests that a
PVD of 20 to 50 should be used.
3.4. FLEXIBLE POLYMERIC MEMBRANES
3.4.1 Introduction
Prefabricated liners based upon sheeting of polymeric materials are of par-
ticular- interest" for the lining of waste stordye and disposal impoundments.
As a group, these materials exhibit extremely low permeability. They have
found substantial use in water impoundments in reservoirs and are being used
in the lining of sanitary landfills and various waste disposal facilities.
Polymeric membrane liner technology is relatively new, particularly with its
application to waste containment, and a wide variety of such liner materials
are being manufactured and marketed*- These-material s vary considerably in
physical and chemical properties, methods of installation, costs and inter-
action with various wastes. Not only are there variations in the polymers
71
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used, but there also is considerable variation in the lining materials of a
given polymer type due to compounding, construction, and manufacturing dif-
ferences among the producers.
In this section, the flexible membrane lining industry, the various polymeric
materials, the testing, the seaning, and the liner construction and methods
of manufacture are described and discussed.
3,4.2 Description of the Polymeric Liner Industry
Basically, the polymeric liner industry is composed of four major segments:
- Raw materials producers
- Manufacturers of sheeting or roll goods
- Fabricators of prefabricated panels
- Installers or construction contractors.
The relationship of these segments is illustrated further in Figure 3-3. A
given company in the industry can perform two or more of these functions,
e.g. a sheeting manufacturer might also fabricate and install; however, that
is not the usual case. Another important factor is that of the design of the
disposal site and the selection of the lining. This function is usually
performed by engineering and consulting firms and at times by fabricators and
installers.
Current representative lists of polymer producers, liner manufacturers,
fabricators, and installers are included in Appendix II. The various seg-
ments of the industry are discussed in the following sections.
3.4.2.1 Raw materials production
The membrane or finished she-eting is made from one or more raw polymers
combined with a variety of compounding ingredients, such as carbon black,
pigments, fillers, plasticizers, processing aids, crosslinking chemicals,
antidegradants and biocides. Table 3-5 presents such a list of polymers by
generic name, their trade names or other common identification, and their
respective producers.
The polymer producers normally supply technical service to reputable sheeting
manufacturers, presenting recommended formulations, and manufacturing pro-
cedures. Some of the polymer producers conduct random monitoring of the
sheet manufacturers to protect their polymer, but such quality control is
growing more difficult to achieve because of the rapid growth of the in-
dustry. The individual polymers are discussed in Section 3.4.3.
3.4.2.2 Preparation of liner compounds and
manufacture of sheeting
The final selection of compounding ingredients for each of the polymers
is the responsibility of the sheeting- manufacturer. The expertise employed
in formulating, mixing, and forming sheets will control the properties of the
finished liner. The polymer and its required compounding ingredients are
72
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FLEXIBLE MEMBRANE LINER INDUSTRY
RAW MATERIAL PRODUCERS
Polymers
• Plastics
• Rubbers
Fabrics
• Square
• Leno
• Other
Other Ingredients
• Fillers/Pigments
• Plasticizers
• Crosslinkers
• Antidegradants
• Processing aids
MANUFACTURERS OF SHEETING
Compounding
Forming process
Calendering
Extrusion
Spread coating
Sheeting
• Thermoplastic
• Crystalline
• Crosslinked
• Fabric reinforced
Narrow Sheeting
«90in.)
Wide Sheeting
(21-33 feet)
in rolls
FABRICATORS
Factory assembly of
sheeting into panels
Panels
«20,000 sq. ft.)
INSTALLERS
Assembly on site of panels
or rolls into liners with field seams
Lined Waste Containment Facilities
Types Owners
• Landfills
• Ponds
• Lagoons
• Pits
• Reservoirs
• Cities/counties
• States
• Industrial
• Landfill operators
Figure 3-3. Basic structure of the polymeric membrane liner industry from
raw material producers to 1 irier "installers. A representative
list of organizations and personnel in the individual segments
of the industry is presented in Appendix II.
73
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TABLE 3-5. POLYMER PRODUCERS
Po 1 yme r
Butyl rubber (IIR)
Chlorinated polyethylene (CPE)
Chlorosulfonated polyethylene (CSPE)
Elasticized polyolefin
Epichlorohydrin rubbers (CO and ECO)
Ethyl ene propylene rubber (EPDM)
Ethyl ene vinyl acetate (EVA)
Fluorocarbon polymers
Neoprene (chloroprene rubber)
Nitrile rubber (NBR)
Polybutylene (PB)
Polyester elastomer
Polyethylene - HOPE
- LOPE
- LLDPE
Polyvinyl chloride (PVC)
Thermoplastic elastomer
Urethane
Trade Name
Butyl rubber4
CPEa
Hypalon
• • •
Herclor
Hydrin
Epcar
Epsyn
Nordel
Royal ene
Vistalon
El va 1 oy
Vi ton/Teflon
Neoprenea
Chemi gum
Hycar
Krynac
NYsyn-
Paracri 1
• * •
Hytrel
« • •
• • •
• • •
PVCa
Santoprene
TPR
• * «
Company
Exxon
Columbian Carbon
Polysar
Dow Chemical
Du Pont
Du Pont
Hercules
B. F. Goodrich
Polysar
Co polymer
DuPont
Uni royal
Exxon
Du Pont
Du Pont
Du Pont
Denka
Goodyear
8. F. Goodrich
Polysar
Copolymer-
Uni royal
Shell Chemical
Du Pont
Many
Many
Many
Borden
General Tire
B.F. Goodrich
Pantasote
Tenneco
Union Carbide
Monsanto
Uniroyal
Many
aGeneric name
74
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often mixed on a mill or in an internal mixer, such as a banbury. The
mixed compound is then converted continuously into sheeting 54 inches to 33
feet in width by hundreds of feet in length by calendering, extrusion, and
spread coating. Descriptions of the manufacturing processes are presented in
Section 3.4.4. A representative list of sheeting manufacturers is presented
in Appendix II.
3.4.2.3 Fabrication
After manufacture and rolling, the narrow sheeting, up to 60 inches in width,
is ready for fabrication into panels. In this step the sheeting is joined
(seamed) together to form panels (up to 100 feet x 200 feet). The size of
the panels is limited by weight (usually about 5,000 pounds) and the ability
of a crew to place it in the field. Various seaming techniques can be em-
ployed including, but not limited to: heat seaming, fusion seaming, dielec-
tric seaming, adhesive systems, bodied solvents and solvent welds. The method
used should be fully specified, including the type of quality control to be
used. Factory seams are usually more reliable than field seams, since they
are made under carefully controlled conditions. If the area to be lined is
small enough, the entire finished liner may be prefabricated in one piece,
eliminating field seaming altogether; this is called a drop-in liner. The
recent introduction of wide sheeting in 22-33 foot widths of some materials
has made the fabrication of panels unnecessary. Such sheetings are brought
to the site in large rolls and the seaming is performed in the field using
thermal or fusion seaming methods.
3.4.2.4 Installation
After the raw materials are produced, compounded, converted into sheeting
and fabricated into panels, the installation is the final step toward com-
pleting the liner project. The installation should be performed by an
experienced liner installer or by a qualified specialty contractor whose
experience is in liner installation, associated earthwork, and piping in-
stallation. However, installation is incomplete until all field seams have
been inspected to the satisfaction of the end user or his representative.
Air lancing, vacuum, mechanical, and ultrasonic methods have been used in the
field to make 100% inspection of seams.
3.4.2.5. Engineering and design services
Another important segment of the liner industry is the engineering and design
services that are furnished by various engineering and consulting firms.
Such services can supply the designs of disposal sites and participate in the
selection of the liner system to be used. They also can supply quality
control services during the installation of the liners.
3.4.3 Polymers Used in Liner Manufacture
Polymers used in the manufacture of lining materials include a wide range of
rubbers and plastics differing in polarity, chemical resistance, basic compo-
sition, etc. They can be classified into four types:
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- Rubbers (elastomers) which are generally crosslinked (vulcanized).
- Plastics which are generally unvulcanized, such as PVC.
- Plastics which have a relatively high crystalline content, such as the
polyolefins.
- Thermoplastic elastomers, which do not need to be vulcanized.
Table 3-6 lists the various types of polymers that are used, indicates
whether they are used in vulcanized or nonvulcanized form, and whether they
are reinforced with fabric. The polymeric materials most frequently used in
liners are polyvinyl chloride (PVC), chlorosulfonated polyethylene (CSPE),
chlorinated polyethylene (CPE), butyl rubber, ethylene propylene rubber
(EPDM), neoprene, and high-density polyethylene (HOPE). The thickness of
polymeric membrane for liners range from 20 to 120 mils, with most in the
20-60 mi 1 range.
Table 3-6. POLYMERIC MATERIALS USED IN LINERS
Polymer
Butyl rubber
Chorinated polyethylene
Chlorosulfonated polyethylene
Elasticized polyolefin
(partial ly 'Crystal 1 i ne)
Elasticized polyvinyl chloride
Epichlorohydrin rubber
Ethylene propylene rubber
Neoprene (chloroprene rubber)
Nitrile rubber
Polyethylene (partially crystal-
line)
Polyvinyl chloride
Use
Thermo-
plastic
No
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
in liners
Vulcanized
Yes
Yes
Yes
No
• n •
Yes
Yes
Yes
• • •
No
No
rei
With
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
Yes
No
Yes
Fabric
nforcement
W/0
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
• • •
Yes
Yes
Most polymeric lining materials are based on single polymers; however, blends
of two or more polymers, e.g. plastic-rubber alloys, are being developed and
used in liners. Consequently, it is difficult to make generic classifica-
tions based on individual polymers of the liners, although one polymer will
76
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generally predominate in the compound. Blending of polymers introduces the
long-range possibility of the need for performance specifications. However,
long-term liner performance in the field cannot, at the present time, be
completely defined by current laboratory tests.
Most of the membrane liners currently manufactured are based on unvulcanized
or uncrosslinked polymeric compounds and thus are thermoplastic. Even if
the polymer in the vulcanized form is more chemically resistant, such as CPE
and CSPE, it is generally supplied unvulcanized because it is easier to
obtain reliable seams and to make repairs in the field. Thermoplastic
polymers can be heat-sealed or seamed with solvent or bodied solvent (a
solvent containing dissolved polymer to increase the viscosity and reduce the
rate of evaporation). Crystalline sheetings, which are also thermoplastic,
can only be seamed by thermal or fusion methods. Information on individual
polymers and liners is presented in subsequent subsections. Subjects covered
on each polymer are: composition, general properties and characteristics,
general use, and specific use in liners.
3.4.3.1 Butyl rubber
Liners of butyl rubber were among the first synthetic liners; they were used
for potable water impoundment and have been in this type of service for about
30 years (Smith, 1980). Butyl rubber is a co^olymer of isobutylene (97%)
with small amounts of isoprene introduced to furnish ?ites for crosslinking
(Morton, 1973, pp. 249-59). The important properties of butyl rubber relative
to its use as a liner are:
a. Low gas and water vapor permeability.
b. Thermal stability.
c. Ozone and weathering resistance.
d. Chemical and moisture resistance.
e. Resistance to animal and vegetable oils and fats.
It is generally compounded with fillers and some oil, and vulcanized with
sulfur. Butyl rubber vulcanizates are highly swollen by hydrocarbon solvents
and petroleum oils, but are only slightly affected by oxygenated solvents and
other polar liquids. Butyl rubber vulcanizates also have high resistance to
mi-neral acids, high tolerance to extreme- temperatures, retention of flexi-
bility throughout service life, good tensile strength, and desirable elong-
ation qualities.
Butyl rubber liners are vulcanized and manufactured in both fabric-reinforced
and unreinforced versions. As they require special room temperature vulcan-
izing adhesives, they are difficult to seam and to repair.
3.4.3.2 Chlorinated polyethylene
Chlorinated polyethylene (CPE) is produced by a chemical reaction between
chlorine-and a high-density polyethylene. Presently available polymers
contain 25-45% chlorine and 0-25% crystallinity. CPE is compounded and used
in both thermoplastic and crosslinked compositions. CPE can be crosslinked
with peroxides but, in liner compositions, it is generally used as a thermo-
plastic.
77
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Since CPE is a completely saturated polymer (no double bonds) it weathers
well and is not susceptible to ozone attack. Compounds of this polymer can
have good tensile strength and elongation. Chlorinated polyethylene is
resistant to deterioration by many corrosive and toxic chemicals. Because CPE
liner compounds contain little or no plasticizer, they have good resistance to
growth of mold, mildew, fungus, and bacteria. Membranes of CPE can also be
formulated to withstand intermittent contact with aliphatic hydrocarbons and
oils. Continuous exposure to aromatics will shorten the service life of the
Itner and, in most cases, CPE 11 ners are not recommended for containment of
aromatic hydrocarbon liquids (Dow, 1977).
CPE can be compounded with other polymers, making it a feasible base material
for a broad spectrum of liners. CPE can be alloyed with PVC, PE and numerous
synthetic rubbers. Nevertheless, at least half the polymer content of CPE
liners is CPE resin. CPE membranes are available in varied thicknesses in
unreinforced or fabric-reinforced versions. As membranes of CPE are generally
unvulcanized, they can be seamed by bodied-solvent adhesives, solvent welding,
or by heat sealing with an air heat gun or by dielectric means. CPE is widely
used in minor amounts to improve the environmental stress crack resistance and
softness of ethylene pol'ymers and to improve the cold crack re?''stance of
flexible polyvinyl chloride.
3.4.3.3 Chlorosulfonated polyethylene (CSPE)
Chlorosulfonated polyethylenes are a family of polymers prepared by reacting
polyethylene in solution witn chlorine and sulfur dioxide. Presently avail-
able CSPE polymers contain from 25 to 43% chlorine and from 1.0 to 1.4%
sulfur. They are used in both thermoplastic (uncrosslinked) and crosslinked
(with metal oxides) compositions. Thermoplastic CSPE is more sensitive to
temperatures than other commonly-used elastomers. It is generally tougher at
room temperature, but . softens mere rapidly as temperatures are increased
(Morton, 1973, pp 337-8).
Chlorosulfonated polyethylene (CSPE) is characterized by ozone resistance,
light stability, heat resistance, good weatherability, and resistance to
deterioration by corrosive chemiccils, e.g. acid and alkalies. It has good
resistance to growth of mold, mildew, fungus, and bacteria. Membra'nes of
this material are available in both vulcanized and thermoplastic forms, but
primarily in the latter. Usually, they are reinforced with a polyester or
nylon scrim and generally contain at least 45% of CSPE polymer. The fabric
reinforcement gives needed tear strength to the sheeting for use on slopes,
and reduces the distortion resulting from shrinkage when placed on the base
and when exposed to the heat of the sun. die thermoplastic version is
available in "potable" and "industrial" grades. The latter is more suitable
for lining industrial and hazardous waste impoundments.
CSPE can be seamed by heat sealing, dielectric heat sealing, solvent welding,
.or by using "bodied" solvent adhesive., Membranes of this polymer do not
crack or fail at extreme temperatures or from weathering. Disadvantages of
unreinforced CSPE membranes are low tensile strength and a tendency to shrink
on exposure to sunlight due to the heat absorbed. Also, thermoplastic CSPE
tends to harden on aging, due to crosslinking by moisture, ultraviolet
) 78
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radiation, and heat and has relatively poor resistance to oils. The harden-
ing can cause problems in repairing damaged sheetings due to crosslinking of
CSPE, which can make it insoluble and difficult to heat seal.
Membranes of CSPE are available in colors other than black, without appre-
ciable loss of other desirable characteristics (Du Pont, 1979).
3.4.3.4 Elasticized polyolefins
Elasticized .polyolefin is a blend of rubbery and crystalline polyolefins.
This polymeric material was introduced in 1975 as a black unvulcanized,
thermoplastic liner, which readily and easily heat sealed with a specially
designed heat welder in the field or at the factory. It has a low density
(0.92) and is highly resistant to weathering, alkalis, and acids (Haxo et
al, 1977). This membrane is unsupported and was manufactured by blow ex-
trusion and supplied in sheets 20 mil thick, 20 feet wide, and up to 200
feet long (Du Pont, 1979), which are shipped to the site for assembly on the
field.
Some difficulties were encountered with elasticized polyolefin in low tem-
peratures and high winds, in oily environments, and in adhesion to struc-
tures. This type of liner was removed from the market, but it is expected
that a modified version will be again manufactured.
3.4.3.5 Epichlorohydrin rubbers (CO and ECO)
Included in this classification are two epichlorohydrin-based elastomers
which are saturated, high, molecular weight, aliphatic polyethers with chlor-
omethyl side chains. The two types include a homopolymer and a copolymer of
epichlorohydrin and ethylene oxide. These materials are vulcanized with a
variety of reagents that react difunctional ly with the chloromethyl group,
including diamines, urea, thioureas, 2-mercaptoimidazoline, and ammonium
salts.
Epichlorohydrin elastomer vulcanizates exhibit the following characteristics:
a. Resistance to hydrocarbon solvents, fuels and oils.
b. Ozone-and weathering resistance.
c. Low rate of gas/vapor permeability.
d. Thermal stability.
e. Good tensile and tear strength.
Epichlorohydrin rubber has a high tolerance for temperature extremes and
retains its flexibility at extreme temperatures throughout its service life.
The homopolymer has a performance range of (J to 160°C. The copolymer shows
improved low temperature flexibility and is recommended for service from -40
to 105°C. Membranes of epichlorohydrin elastomer are seamed with room
temperature vulcanizing adhesives.
.3.4.3.6 Ethylene propylene' rubber tEP'DM)
Ethylene propylene rubbers are a family of terpolymers of ethylene, pro-
pylene, and a minor amount of nonconjugated diene hydrocarbon. The diene
79
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supplies double bonds to the saturated polymer chain to supply chemically
active sites for vulcanization, usually with sulfur. These rubbers vary in
ethylene:propy1ene ratio, in the type and amount of the third monomer, and in
molecular weight. Although EPDM liners are generally based on vulcanized
compounds, thermoplastic EPDM liners are also available. Both versions are
manufactured as fabric-reinforcec and unsupported sheeting.
Liners based on vulcanized EPOM compounds have excellent resistance to
weather and ultraviolet exposure and, when compounded properly, resist
abrasion and tear. EPDM liners tolerate extremes of temperature, and main-
tain their flexibility at low temperatures. They are resistant to dilute
concentrations (10% by weight) of acids, alkalis, silicates, phosphates, and
brine, but are not recommended for petroleum solvents (hydrocarbons) or for
aromatic or halogenated solvents.
Vulcanized EPDM membranes require the use of special cements and careful
application to assure satisfactory field seaming. The proposed seam con-
struction should be tested in the service environment to assure durability.
Thermoplastic EPDM liners are seamed by thermal methods.
Because of its excellent ozone resistance, minor amounts of EPDM are some-
times added to butyl to improve the weather resistance of the latter.
3.4.3.7 Neoprene
Neoprene is the generic name of synthetic rubbers based upon chloroprene.
These rubbers are vulcanizable, usually with metal oxides, but also with
sulfur. They closely parallel natural rubber in mechanical properties, e.g.
flexibility and strength. However, neoprene is superior to natural rubber in
its resistance to oils, weathering, ozone, and ultraviolet radiation. Neo-
prene is resistant to puncture, abrasion, and mechanical damage. Neoprene
membranes have been used primarily for the containment of wastewater and
other liquids containing traces of hydrocarbons. They also give satisfactory
service with certain combinations of oils and acids for which other materials
do not provide long-term performance (Lee, 1974).
Neoprene sheeting for liners is vulcanized, thus vulcanizing cements and
adhesives must be used for seaming.
3.4.3.8 Nitrile rubber
This class of polymers is a family of copolymers of butadiene and different
amounts of acrylonitrile ranging from 18 to 50%. The principal feature of
these copolymers is their oil resistance, which increases with increasing
acrylonitrile content. Nitrile rubber is prepared by emulsion polymerization
at different temperatures.
In most applications, nitrile rubber is compounded with plasticizers and is
vulcanized. However, it is also blended with other polymers such as poly-
styrene, phenolics, and PVC to produce thermoplastic compositions that range
in flexibility from rubbery compositions to hard impact-resistant plastics.
80
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Nitrile rubber is used by the lining industry generally in blends of polymers
to produce thermoplastic sheetings which feature oil resistance. The nitrile
rubber is mixed with PVC in amounts less than 50% to yield compounds in which
it acts as a nonmigrating and nonextractable plasticizer.
3.4.3.9 Polyethylene
Polyethylene is a thermoplastic crystalline polymer based upon ethylene. It
is made in three major types: (1) low-density polyethylene (LOPE), (2) linear
low-density polyethylene (LLDPE), and (3) high-density polyethylene (HOPE).
The properties of a polyethylene are largely dependent upon crystallinity and
density. Of the three types, high-density polyethylene polymers exhibit the
greatest resistance to oils, solvents, and permeation by water vapor and
gases. Unprotected clear polyethylene degrades readily on outdoor exposure,
but the addition of 2 to 3% carbon black can produce improved ultraviolet
light protection. Polyethylenes, as generally used, are free of additives
such as plasticizers and fillers.
LDPE and HOPE types of polyethylene have been used as liners. Nonfabric-
reinforced membranes of low-density polyethylene have been used for 25 to 30
years (Hickey, 1969) in lining canals and ponds. The low-density polyethy-
lene (LDPE) available in thin sheeting tends to be difficult to handle and to
field seam. Also, it is easily punctured under impact such as when rocks are
dropped on the lining; however, it has good puncture resistance when buried.
Linings of high-density polyethylene (.HOPE), which have recently been intro-
duced, are available in sheetings of 20 to 120 mils in thickness; special
seaming equipment has been developed for making seams of these sheetings both
in the factory and in the field. This type of liner is stiff compared to
most of the other membranes described. Liner materials of LLDPE, a recently
developed version of polyethylene, have not as yet been introduced on the
market in thicknesses of 20 mils or greater.
3.4.3.10 Polyvinyl chloride
The polymer polyvinyl chloride is produced by any of several polymerization
processes from vinyl chloride monomer (VCM). It is a versatile thermoplas-
tic, which is compounded with plasticizers and other modifiers to produce a
wide range of physical properties.
PVC liners are produced in roll form in various widths and thicknesses. Most
liners are used as unsupported sheeting, but fabric reinforcement has been
used. PVC compounds contain 25% to 35% of one or more plasticizers to
make the sheeting flexible and rubber-like. They also contain 1% to 5% of a
chemical stabilizer and various amounts of other additives. The PVC compound
should not contain any water soluble ingredients. A wide choice of plasti-
cizers can be used in PVC sheeting, depending upon the application and
service conditions under which the PVC compound is to be used. Plastj-
cizer loss during service is a source of PVC liner deterioration. There
are three basic mechanisms for plasticizer loss: volatilization, extraction,
and microbiological attack. The,use of .the proper plasticizers and an
effective biocide can virtually eliminate microbiological attack and minimize
volatility and extraction. The PVC polymer, itself, is not affected by these
conditions. It is affected, however, by ultraviolet exposure.
81
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The principal reason for loss of plasticizer is by volatilization in the heat
of the sun rather than solution in the waste fluid. Carbon black prevents
ultraviolet attack but does cause the absorption of solar energy raising the
temperature to a high level to cause vaporization of plasticizer. A soil or
other suitable cover material used to bury the liner protects it from ultra-
violet exposure and reduces the rate of plasticizer loss. PVC sheeting is
not recommended for exposure to weathering and ultraviolet light conditions
during its service life. In some burial tests and in some liner applications,
PVC sheetings have become stiff, presumably due to loss of plasticizers; some
plasticizers can be degraded by microrganisms, while others can be extracted,
to a limited extent, by water.
Plasticized PVC sheeting has gcod tensile, elongation, and puncture and
abrasion resistance properties. It is readily seamed by solvent welding,
adhesives, and heat and dielectric methods.
PVC membranes are the most widely used of all polymeric membranes for waste
impoundments. They show good chemical resistance to many inorganic chemicals
(Chan et al, 1978, p 19); however, they are attacked by many organic chem-
icals, particularly hydrocarbons, solvents, and oils which extract the plas-
ticizer. Special compounds of PVC are available, designated as Oi1-Resistant
PVC (PVC-OR), that possess hign resistance to oil attack. These "oil-re-
sistant" grades of sheeting must be made with "specialty" plasticizers; the
PVC polymer is inherently resistanc to the effects of oils.
Polymers such as nitrile rubber, CPE and ethylene vinyl acetate (EVA) inter-
polymer may be used to replace the liquid plasticizers so that the PVC liner
is not affected by the waste fluid.
3.4.3.11 Thermoplastic elastomers (TPE)
Thermoplastic elastomers are a relatively new class of rubbery materials
(Walker, 1979). They include a wide variety of polymeric compositions from
highly polar- materials, such as che polyester elastomers, to the nonpolar
materials, such as- ethylene-propylene block polymers. These polymers are
thermoplastic and nonvulcanized. They are processed and shaped at relatively
high temperatures at which they are plastic; when they are cooled to normal
ambient temperatures, they behave like vulcanized rubbers. Products made of
these polymers have an upper temaerature limit which occurs substantially
above the temperatures encountered in waste disposal facilities.
Of particular potential interest for use in liners are the polyolefin thermo-
plastic elastomers, such as thermoplastic EPOM, which are probably related to
the elasticized polyolefins, and nitrile rubber/PVC blends for oil resistant
liners. Such liner materials are now under development and testing.
Nitrile/PVC thermoplastic elastomer blends have- excel lent oil, fuel, and
water resistance with high tensile strength and excellent resistance to ozone
and weathering. Blends tend to stiffen at low temperatures but remain
serviceable.
82
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As with liners of other thermoplastic polymers, liners of thermoplastic
elastomers can be heat sealed to make seams and should be easy to repair;
however, their durability in various chemical environments remains to be
tested.
3.4.4 Membrane Manufacture
The three basic methods used in the manufacture of polymeric sheeting for
liner use are calendering, extrusion, and spread or knife coating. Calen-
dering is used in forming both unsupported and fabric-reinforced sheeting,
whereas extrusion is only used in making unsupported 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 the sheeting. 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 shown in Figure 3-4. The ar-
rangement for preparing a single-ply sheeting on a 3-rol 1 calender is shown
in Figure 3-5. Unsupported sheeting is usually of single-ply construction;
however, some manufacturers have resorted to multiple plying of unsupported
liners to eliminate the formation of pinholes through the sheet. By manufac-
turing sheeting in this manner, the probability of a pinhole in one ply
coinciding with a pinhole in another is remote.
Reinforcing fabric can be placed between the plies of the polymeric compound
to produce a supported liner. 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 some are 20 x 20
ends per inch. Figure 3-6 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 lining materials are usually
treated with an adhesive coating which chemically reacts with the membrane
material during the curing cycle to produce adhesion to the polymer compound.
The extrusion technique is used primarily with polyolefins, such as polyethy-
lene, and with elasticized polyolefin. For thinner films, a tube of film is
produced and slit to form a sheet. For the thicker gage polyethylenes,
thick sheets are extruded directly with proprietary extruding equipment.
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 clean compound for the calender or extruder.
83
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Vertical
Offset top roll
(a)
Inverted L
Vertical
Inverted L
Figure 3-4.
Roll configuration of calenders: (a)
(b) four-roll calenders (Blow, 1971
three-roll calenders, and
Spread coating is performed only on fabrics having high numbers of thread
ends per inch, [n 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 polyner coating. The solvent is evaporated by
drawing the coated fabric through a heated chamber and the solvent is re-
covered. Upon removal from the heated areas, the sheeting is cooled and
rolled (Blow, 1971, p 285).
3.4.5 Testing of Flexible Polymeric Membranes
3.4.5.1 Introduction
Because of the wide range of compositions and constructions of flexible
polymeric membrane liners that are currently available and those being devel-
oped for lining waste .impoundments, testing of the membranes is needed for a
number of purposes. The liner manufacturer needs to test the sheeting as he
uses new polymers and develops new compounds and constructions. He needs
84
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FRONT
REAR
PRESSURE
ROLL
SPREADER ROLL
PENCIL BANK
WIND-UP
LINER
LET-OFF
Figure 3-5. Calender arrangement for coati
with pencil bank (Banks, 1966).
IDLER ROLL
coating sheeting on one-pass or ply-up
tests to control the quality of the liner he is manufacturing. Before sheet-
ing is selected and purchased, the site-owner needs methods to test sheetings
to determine whether or not one or more meets the requirements of the design.
These test methods may take the form of compatibility studies between the
waste and the lining materials to try to predict the performance of a poten-
tial sheeting in service. The sheeting may be
fingerprint the compound. A sample taken from a
being installed may be tested by the owner to
material being placed in the field. Samples may
assess the performance or condition of the liner.
particularly with reference to polymeric membranes
disposal facilities, is described by Haxo (19,81)..
tested to characterize or
sheeting in the process of
assure the quality of the
be tested during service to
The testing of materials,
for the lining of waste
The testing of a polymeric membrane liner at the time of placement can be used
1) as a means of characterizing the specific sheeting and 2) as a baseline for
monitoring- the effects of exposure on the liner. Eventually it is expected
85
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Manufacturer F. 30 mils (0.76 mm), B-5602. Photo
P222-0-6S685
Manufacturer A. 60 mill (1.52 Trim). B-46O6. Photo
PX-D-68886
Manufacturer G. 30 mill (0.76 mmj, B-5540. Photo
PX-O-68887
Manufacturer H. 30 mils (0.76 mm). B-5560. Photo
PX-D-68888
F19ure 3-6-
(Hickey, 1971).
at 6x magnifica-
86
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that correlations will be developed between the simulation tests and field
performance to yield a body of tests which can effectively predict the
field performance of a lining material in a given situation.
Polymeric membranes are tested in accordance with many different methods,
depending upon the type of membrane liner; sheetings used as liners have been
developed by three different industries, i.e. rubber, plastics, and textile.
Each has developed standard test methods. Some test methods for one type of
sheeting are not appropriate for other types; for instance, using a dumbbell
with a quarter-inch restricted area, such as is used in the testing of rubber
vulcanizates, is not satisfactory for measuring the tensile properties of
fabric-reinforced materials.
From the point of view of testing, there are four basically different types of
polymeric membranes:
- Crystalline polymers without fabric reinforcement.
- Fabric-reinforced sheetings which can be based upon either cross! inked
or thermoplastic polymers.
- Thermoplastics or uncrosslinked polymers without fabric reinforcement.
Vulcanized or crosslinked elastomers without fabric reinforcement.
The methods used for testing polymeric lining materials can be grouped into
four categories:
- Analyses to assess composition and to fingerprint.
- Tests of physical properties, including information regarding con-
struction and dimensions of the membrane.
- Tests to determine properties in stress environments and aging tests in
specific exposures or compatibility tests.
- Tests of durability of lining materials under conditions that simu-
late actual field service.
These tests can include measurements of the following properties:
-Analytical properties before and after exposure to different environ-
ments.
- Ash.
- Differential scanning calorimetry if liner material is
crystalline.
- Extractables.
- Gas chromatography and gas chromatograph/mass spectroscopy.
- Specific gravity.
- Thermogravimetric analysis.
- Volatiles.
- Physical properties before and after exposure to different environments:
- Burst strength (hydrostatic resistance).
- Dimensional stability.
87
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- Hardness.
- Modulus of elasticity if liner material is crystalline.
- Ply adhesion for fabric-reinforced sheeting.
- Puncture resistance.
- Seam strength of factory and field-prepared seams.
- Tear resistance.
- Tensile properties.
- Thickness.
- Water vapor transmission.
The measurement of these properties represents a body of tests which can be
used to monitor the effects on a liner of an environmental exposure. In
addition, a variety of tests are performed after exposure to different
environmental conditons:
- Environmental and aging effects upon properties:
- Environmental stress cracking if liner material is crystalline.
- High temperature.
- Low temperature.
- Water absorption.
- Tests of durability under different conditions that simulate service:
- Retention of selected properties on or during the burial
test.
- Retention of selected properties on or during the immersion in
water, standard test liquids, and waste liquids. ^
- Retention of selected properties on or during the outdoor roof
exposure.
- Retention of selected properties on or during the pouch test,
except vulcanized sheetings.
A change in one property during an exposure is usually accompanied by changes
in other properties, but at this stage no one property has been correlated
with liner performance in the field. In the subsequent subsections, we
discuss these properties and how they are tested. A list of specific test
methods can be found in Table 3-7. Many of the physical and simulated service
tests that are used in the rubber industry are described in DuPont (1963).
'3.4.5.2 Analytical properties of polymeric membrane liners
Volatiles. "Volatiles" is the percent weight lost by a specimen of liner on
drying in a desiccator at 50°C and then heating in an oven at 105°C. If the
liner has been exposed and absorDed volatile liquids the portion of weight
lost in the desiccator represents the water fraction and the portion lost at
105°C represents the low-boiling organic fraction that the liner absorbed.
Changes in the volatile fraction can'be used as a means of monitoring a
material during exposure to waste liquids. The percent of swell can be
estimated from the volatiles by dividing that number by the nonvolatile
fraction; the amount of plasticizer lost to the waste liquid can be calculated
I
38
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TABLE 3-7. APPROPRIATE OR APPLICABLE TEST METHODS FOR UNEXPOSED MEMBRANE LINERS
Lmer material property
Analytical properties
Volatiles
Extractables
Asn
Specific gravity
Physical properties
Thicxness - total
Coating over fabric
Tensile properties
Tear resistance
Modulus of elasticity
Hardness
Puncture resistance
Hydrostatic resistance
Seam strength
Shear
Peel
Ply adhesion
Environmental and
aging effects
Ozone cracxing
Environmental stress
cracxing
Low temperature testing
Tensile properties ac
elevated temperature
Dimensional stability
A1r oven aging
Water vapor transmis-
sion
Water absorption
Immersion in standard
fluids
Soil burial
Membrane
Thermoplastic
MTM-l*
MTM-20
ASTM 0297,
1 34
ASTM 0792, Mtd A
ASTM 0638
na
ASTM 0882,
ASTM 0638
ASTM 01004
(mod)
na
ASTM 02240
Duro A or 0
FTMS 1018,
Mtd 2065
AS'M 0751, Mtd A
ASTM 0815,
Mtd 3 jmod)
ASTM 0882,
Mtd A (mod)
ASTM Q413, Macn
Mtd Type 1 (mod)
ASTM 01876 (mod)
na
ASTM 01149
na
ASTM 01790
ASTM 0638 (mod)
ASTM 01204
ASTM 0573 (mod)
ASTM E96, Mtd 8W
ASTM 0570
MTM-3C
ASTM 03083
1 iner without fabric
Crossl mned
MTM- la
MTM-20
ASTM 0297,
« 34
ASTM 0297,
1 15
ASTM 0412
na
ASTM 0412
ASTM 0624, Die C
na
ASTM 02240
Ouro A or 0
FTMS 1018,
Mtd 2065
ASTM 0751, Mtd A
ASTM 0816,
Mtd 3 (mod)
ASTM 0882.
.Mtd A (mod)
ASTM 0413, Mach
.Mtd Type 1 (mod)
ASTM 01876 (mod)
na
ASTM 01149
na
ASTM 0746
ASTM 0412 (mod)
ASTM 01204
ASTM 0573 (mod)
ASTM £96, .Mtd 8W
ASTM 0471
MTM-3*1
ASTM 03083
reinforcement
Crystalline
MTM-la
MTM-2b
ASTM 0297,
1 34
ASTM 0792, 'Mtd. A
ASTM 0638
na
ASTM 0638 (mod)
ASTM oioo4
ASTM 0882, Mtd A
ASTM 02240
Ouro A or 0
FTMS 1018,
.Mtd 2065
ASTM 0751, Mtd A
ASTM 0816,
.Mtd 3 (mod)
ASTM 0882,
.Mtd A (mod)
AS'M 3413, Macn
Mtj ~yP« 1 (mod)
ASTM 31876 (mod)
na
na
ASTM 01693
ASTM 01790
ASTM 0746
ASTM 0638 (mod)
ASTM 01204
ASTM 0573 (mod)
ASTM £96, Mtd 3W
ASTM 0570
MTM- 3°
ASTM 03083
Fabric-reinforced
MTM-13
(on selvage and
"einforced sheeting)
MTM-20
(on selvage and rein-
forced sheeting)
ASTM 0297.
fl 34
(on selvage)
ASTM 0792, .Mtd A
(on selvage)
ASTM 0751, 1 5
Optical Method
ASTM 0751, Mtd A and 8
(ASTM 0638 on selvage)
ASTM 0751, Tongue Mtd.
na
ASTM 32240
3uro A 3r 3
!sei /age :nl/i
F'MS 1313,
-T3 2065
ASTM 3751, Mta A
ASTM 3815,
Mtd 3 itiod)
ASTM 0882,
Mtd A (mod)
ASTM 3413, Mach
• Mtd Type 1 .nod)
ASTM 01376 (mod)
ASTM 0413, Mach
ASTM 0751, 1 39-42
ASTM 01149
na
ASTM 02136
ASTM 0751 Mtd d (mod)
ASTM 01204
ASTM 0573 (mod)
ASTM £96, Mtd 3W
ASTM 0570
MTM- f
ASTM 03083
na » Not applicable.
JMatrecon Test Method-!,
°Matrecon Test Metnod-2,
cMatrecon Test Metnod-3,
see Appendix III-O.
see Appendix III-E.
see Appendix III-A.
89
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from an analysis of the "extractables" (see below) if the original plasticizer
content is known.
Ash. The ash content of a liner material is the fraction that remains after a
sample is thoroughly burned at an elevated temperature, e.g. 550°C. The ash
content is usually made up of inorganic materials that have been used as
fillers or as curatives in the polymeric coating compound. As different
manufacturers formulate their compounds differently, determining the ash
content can be a way to "fingerprint" a polymeric liner compound. The residue
obtained by ashing can be retained for further analyses, such as metals con-
tent, needed for further identification and to determine the trace elements
that may have been absorbed by the liner. The test method described in ASTM
D297, Paragraph 34, is generally followed in performing this analysis.
Extractables. The extractable content of a polymeric sheeting is the fraction
that can be extracted from a sample of the liner with a solvent that neither
decomposes nor dissolves the liner. A recommended test procedure for this
analysis of unexposed sheeting, showing the specific solvents that can be used
for each type of polymer, is given in Appendix III-E. "Extractables" consist
of plasticizers, oils, or other solvent-soluble constituents that impart or
help maintain specific properties, such as brittleness or processability. A
measurement of extractable content and analytical study of the extract can be
used as part of the "fingerprint" of a sheeting. An important use of this
test is to monitor the effects of exposure to waste liquids. During exposure
to a waste liquid, constituents in the original liner compound may be ex-
tracted resulting in a change in properties of the liner. For instance,
during exposure to some waste liquids, the plasticizer can be extracted from a
PVC liner and cause the sheeting to harden, become brittle, and shrink, thus
increase the possibility of failure. The loss o* plasticizer will appear in
the analysis as a lower extractable content. Another possible effect of an
exposure that can be monitored :>y measuring the extractable content is the
case where a sheeting absorbs non-volatile elements such as higner molecular
weight oils from a waste and becomes soft. Softening of the liner is also
incurred by the absorption of waste which may include both water and organic
compounds. To determine the extractables of an exposed liner, the volatile
fraction must oe removed. A flow diagram of a recommended analysis of exposed
polymeric liner materials is presented in Appendix III-F. This procedure
features the initial removal of absorbed wastes by drying a specimen of the
liner in a desiccator at 50°C followed by the removal of the organic volatiles
by heating at 105°C. The extraction is then performed on the devolatilized
sample. The organic volatiles and.extracts can be analyzed separately if
needed by infrared and gas chromatography.
Gas chromatograph/mass spectroscopy (GC/MS). The gas chromatograph is capable
of separating a mixture of gases into chemically pure components by the
retention time of the component on the chromatographic column installed in the
instrument. The information is sufficient to prove that an unknown and a
standard are different, should they exhibit different different retention
times. It is not sufficient to prove-conclusively that an unknown and stand-
ard having the same retention time are the same. The extra information
required to show conclusively identity must be provided by a more powerful
detector than coventional flame ionization or thermal conductivity detectors.
90
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The mass spectrometer is ideally suited to this purpose. It operates by
destructively ionizing the pure organic fractions arriving at it from the GC
column, and then further separating the molecular fragments on the basis of
their ionic charge and molecular weight. The data resulting is highly
complex and very reproducible. It can be used 1) to identify the component
on the basis of these data alone, as a "fingerprint" and, with access to a
library or computer data base, also to identify conclusively the component.
In either case, the reproducibility and high information content of the GC/MS
data makes the probability of identification errors very low.
Thermogravimetric analysis (TGA). TGA is a technique for assessing the
composition of materials by their loss in weight on heating at a controlled
rate in an inert or an oxidizing atmosphere. 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, char,
and ash remain. The introduction of oxygen into the system will burn off the
char and carbon black. Thus, from the weight-time curve which can be related
to weight and temperature, the amounts of volatiles, plasticizer, polymer,
carbon black, and ash can be calculated. In some cases, thermogravimetric
analysis can replace measurements of the volatiles, ash, and extractables
contents discussed above. The TGA curve and the derivative of the TGA
curve can thus be used as part of a "fingerprint" of a polymeric composi-
tion. This technique is described by Reich and Levi (1971).
Differential scanning calorimetry (DSC). O.SC is a thermal technique for
measuring tne melting point and the level of crystal 1inity in partially
crystalline polymers, such as the polyolefins, e.g. polyethylene and poly-
butylene. This technique measures the heat of fusion of a crystalline
structure. It can also give an indication regarding modification of crystal-
line sheeting with other polymers by-alloying. Thus, this type of analysis
can be used as a means of fingerprinting crystalline polymeric liner materi-
als, particularly high-density polyethylene, and assessing the effects
of aging and exposure to wastes. This equipment can also be used to measure
second order transitions of polymers and plasticized polymers. This transi-
tion is the temperature at which a polymer converts from a brittle, glassy
state to an amorphorus, rubbery state and is tnus related to its low temper-
ature properties. These techniques are described by Boyer (1977) and Ke
(1971).
Speci fie gravity. Specific gravity and density are important, easy to
determine, characteristics of a material which can give an indication of the
composition and identification of a compound. -On expos'ed liners, specific
gravity can be measured only after the liner has been devolati1ized. Care
must be taken to thoroughly dry the specimen before placing it in the oven at
105°C to avoid bubbles forming in the sample. ASTM Method 0792, Method A,
and D297, Paragraph 15, are generally used in performing this test.
3.4.5.3 Physical properties of polymeric membrane liners
Tensile properties. Tensile properties of polymeric sheetings are measured in
tension with a stress-strain tester. The properties that are measured depend
on the type of polymeric sheeting and include the following:
91
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- Tensile at fabric break (if fabric-reinforced).
- Elongation at fabric break (if fabric-reinforced).
- Tensile at yield (if a crystalline liner).
- Elongation at yield (if a crystalline liner).
- Tensile at break of sheeting.
- Elongation at break of sheeting.
- Modulus at specified elongations, e.g. 100% and 200%.
The test methods, including the test specimens, vary with the type of material
The basic purpose for measuring tensile properties is that the test gives a
good indication of the quality of a compound of a given polymer. Absolute
tensile strength values from polymer to polymer should not be compared unless
tensile strength is an important property in the performance of the product.
Tensile testing is probably the most widely used test method in the rubber and
plastics industries for testing polymer compositions and products. It must be
recognized that, even for a given polymeric material, tne values for the
tensile properties vary with speed of test, i.e. the rate of jaw separation,
specimen size, direction of test with respect to the grain in the sheeting,
temperature, and humidity.
Changes in tensile properties can be used to monitor the effects of exposure
on a lining material. In many rubber and plastics applications, a 50% loss in
tensile strength in elongation, or a 50% increase or decrease in modulus,
indicates that the product has become unserviceaole. These criteria are
probably not applicable to liners; nevertheless, major changes in properties
in relatively short times i'ndicate the incompatibility of a liner and a
waste.
The test procedures followed in determining tensile properties for the dif-
ferent types of sheetings are:
Thermoplastic sheeting: ASTM D882
ASTM D638
Crosslinked rubber: ASTM D412
Crystalline polymer: ASTM D638
Fabric reinforced sheeting: ASTM D751, Methods A and B
Selvage edge ASTM D882, D638, or 0412, depending on
the^type of "polymer coating compound
Modulus of elasticity. The modulus of elasticity is a measure of the stiff-
ness or n.gidity of "stiff materials such as HOPE; it is defined as the. ratio
92
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of stress to corresponding strain in the part of the stress strain curve that
behaves according to Hooke's law, i.e. the stress values are linear with
respect to the spaces. It is also known as Young's modulus. ASTM D883,
Method A, is followed in determining the modulus of elasticity of crystalline
membranes.
Hardness. Hardness, in terms of the standard tests for hardness of polymeric
materials, 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 as determined by indentation and other measured
properties, it is related to Young's modulus (ASTM 01415-81). Hardness is an
easily measured indicator of the quality of a polymeric material and can be
used to monitor change in a material. ASTM 02240 is generally used to measure
this property; the A scale is used for soft, rubbery materials and the D scale
is used for hard materials, i.e. materials that are harder than 85 measured on
the A scale.
Tear resistance. Tear resistance is a measurement of the force required to
tear a specimen with or without a controlled flaw. The measurement serves as
an indication of the quality of the compound and of the mechanical strength of
a sheeting, particularly to the type of stresses encountered during installa-
tion. The measurement is also used to monitor the effects of an exposure on a
material. The magnitude of the tear value is sensitive to the rate of test
and the shape and size of the test specimen. Coated fabrics are normally run
at 12 inches per minute. Unreinforced vulcanized sheetings are tested at 20
ipm. It is recommended that unreinforced thermoplastics be tested at 20 ipm
and crystalline materials at 2 ipm. A variety of ASTM tests are used.
Thermoplastics and crystalline materials are usually tested according to ASTM
1004; crosslinked rubber sheetings are tested according to ASTM 0624, using
Die C, and coated fabrics are tested according to ASTM 0751, using a "tongue"
specimen. Because of the low adhesion between the fabric and the polymer
coating, the fabric pulls out of the polymer matrix resulting in the threads
bundling at the tip of the tear and yielding excessively high test values.
As a consequence, a larger specimen is used by the liner industry than is
called for in the ASTM method.
Puncture resistance. Puncture resistance is a measurement of the force
required to puncture a sheeting with a standard probe. The measurement
serves to indicate the ability of a material to withstand puncture from above,
e.g. equipment, foot traffic, deer hooves, etc and from below, e.g. by
irregularities in the substrate, etc. Puncture resistance can be used to
monitor t"he effects of an exposure on a sheeting. There is no universally
accepted method for testing puncture resistance. We recommend and use the
method described in Federal Test Method Standard 101B, Method 2065, for
measuring puncture resistance, particularly of unreinforced sheetings: The
usefulness of this test for fabric-reinforced flexible membrane is limited
because of the openness of the weaves normally used. The hydrostatic re-
sistance test described below is useful for. coated fabric. Neither test,
however, measures the resistance to puncture of a liner by a sharp object
falling on the sheeting during installation. Our recommended method reflects
more the resistance to a slow puncture.
93
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Hydrostatic resistance tests. This test measures the hydrostatic pressure
required to Durst a specimen of sheeting. ASTM D751, Method A - Procedure 1,
which is designed for fabric-reinforced sheeting, is commonly used to measure
this property of most membrane liners.
Water vapor transmission. To measure water vapor transmission, ASTM E-96
Method BW fs used. Trf this test, a cup with a membrane specimen cover is
placed in an inverted position in a controlled temperature, humidity, and air
stream. Loss in weight of water from the cup is observed as a function of
time. This test is intended for those applications in which one side is
wetted under conditions where the hydraulic head is relatively unimportant and
the -moisture transfer is goverened by water vapor diffusion forces. The
driving force is supplied by the difference in the relative humidity on the
two sides of the membrane.
3.4.5.4 Tests of membranes under environmental stress
Environmental stress-cracking. A stress-crack is defined as an external or
internal crack in a plastic caused by tensile stresses less than its short-
time mechanical strength. Under certain conditions of stress and exposure to
soaps, oils, detergents, or other surface-active agents, certain grades of
polyethylene in particular may fail by cracking. Proper selection of the
polyethylene or addition of one of a variety of ruobery polymers can eliminate
this deficiency. ASTM 01693 can be run to indicate the susceptibility of a
polyethylene sheeting to environmental stress-cracking. In this test, speci-
mens having a controlled imperfection are bent and exposed to the effects of a
designated surface-active agent. Failure comes with a breaking of the speci-
men.
High-temperature properties. A liner material can encounter higher than
normal temperature prior to installation, during installation, and during
service. Thermoplastic liners, 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 sheeting may split or an unsup-
ported sheeting may tear and become unserviceable. During installation,
the black sheeting 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 temperatures. Also, higher temperature can cause shrinkage and
distortion of the sheeting. Appropriate tensile, modulus, and tear tests can
be run at temperatures of 60°C or higher to determine the effects of elevated
temperature.
Low temperature properties. Liners can encounter low temperatures before
installation, during installation, and in some cases during service depending
upon the climate in which they are Installed.
Some lining materials are quite sensitive to low temperature, becoming
stiff and even brittle on exposure to moderately low temperatures. The
rate at which these changes take place, and the time it; takes for a material
to soften when its temperature is raised, vary. Some changes can take an
extended time; consequently, short-term tests can be quite misleading.
94
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A variety of tests exist for measuring the effects of low temperatures upon
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 Temperature of Plastics and Elasto-
mers by Impact.
ASTM D1034 - Stiffness properties of Plastics as a Func-
tion of Temperature by Means of a Torsion Test
(also used on rubber compositions).
ASTM D1790 - Brittleness Temperature of Plalstic Film by Impact.
ASTM D2136 - Low Temperature Bend Test of Coated Fabrics.
ASTM D2137 - Brittleness Point of Flexible Polymers and Coated
Fabrics.
Water absorption. Absorption of water can have adverse effects on many
polymeric compositions. Since most waste fluids contain water, the effects of
immersion in water on lining materials need to be determined. The effects of
immersion are monitored in terms of either change in weight, change in di-
mensions, or both. A water absorption test is included to provide a relative-
ly precise comparative index of all the sheetings in the test. Extended
immersion periods are recommended. The test specimens are large enough to get
a tensile dumbbell out of or to pull as a strip to get an indication of the
'effect of water absorption on tensile properties. Water absorption tests at
elevated temperatures accelerate the effects of immersion in water. Prior
testing has shown that water absorption tests run at 70°C are too severe as
accelerated aging tests for most materials. We recommend performing water
absorption tests on all the sheetings at room temperature (23°C) and at 50°C.
Water absorption tests were run according to ASTM 0471 and 0570.
3.4.5.5 Testing of seam strength of factory and field systems
A critical factor in the functioning and durability of a polymeric membrane
liner in service is the seam strength between assembled panels of the sheet-
ing. Testing of seams is performed to ensure that the method of seaming a
particular material is adequate. Testing of the seams also can be performed
as part of immersion testing with wastes and with standard fluids, because the
effect of the wastes on the seams can vary, particularly if the seams are
fabricated with adhesives.
Seams are tested in shear and peel modes both dynamically, in which an in-
creasing load is applied, and statically, where a constant load is applied and
maintained. Elevated temperatures are often used in seam strength tests.
The peel test of seam strength is significantly-more sensitive to the effects
of aging and exposure than shear testing.
95
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Seam strength is run in shear according to ASTM D816, Method B (Modified) and
D882, Method A (Modified). Seam strength in the peel mode is run according to
ASTM D413, Method Type 1, and D1876.
3.4.5.6 Compatibility and Durability Tests
Tests for the compatibility of 'liner materials with wastes and their durabil-
ity on long-term exposure are described in Chapter 4.
3.4.6 Seaming of Polymeric Liner Membranes
3.4.6.1 Introduction
Critical to the effective performance of polymeric membrane liners of impound-
ments and solid waste landfills is the construction of continuous watertight
barriers of approximately uniform strength. As indicated in the discussion of
membrane liners in subsection 3.4.2.2, in the case of most polymeric membrane
liners, sheetings are manufactured in relatively narrow widths (less than 90
inches) that are seamed together in the factory to make large panels. These
panels, in turn, are assembled at the disposal or impoundment site to make
large, continuous sheets which can range up to many acres in area. Therefore,
in a liner installed in this manner there are 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. Seaming in the field can pose
difficulties, largely due to variability in the ambient conditions. According
to the available information, seams appeared to be the most likely source of
liner problems and failure. Recently, several lining materials made in wider
sheetings have been introduced, i.e., in widths ranging from 21 to 33 feet;
these materials are brought to the site in large rolls and seamed in the
field,-thus eliminating factory seaming.
In order to function as a liner, a sheeting must have a bondin'g system
which can be used to fulfill the following requirements:
*
1. The bond between the sheets or panels must be continuous for the
length of the seam.
2. The bond between the sheets must approximate the strength of the
sheeting and must maintain its strength throughout the service
1ife of the sheeting.
3. The bond must be capable of being formed in the field.
A variety of bonding systems are used in the seaming of polymeric membranes.
Selection of the optimum system for a given liner will depend largely on the
polymer. Certain techniques or seaming systems are incompatible with certain
liner materials. For instance, dielectric seaming cannot be used to seam a
butyl rubber sheeting. In addition, some adhesives are designed for use with
a specific sheeting 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. For instance, the manufacturers of the
96
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CPE sneeting used as a primary test specimen recommended three types of
bonding systems and specific systems within each type.
The following is a list of seaming techniques that are currently used either
in the factory to fabricate panels, or in the field to assemble the panels
into a final liner, or both:
- Solvent "welding".
- Bodied solvents.
- Solvent cements.
- Contact cements.
- Vulcanizing adhesives.
- Tapes.
- Thermal techniques.
Heat guns.
Dielectric (factory).
Fusion (field).
Mechanical methods for seaming, though adequate for water containment, are not
considered adequate for seaming liners for waste storage and disposal facili-
ties. Table 3-8 presents a list of the possible alternative methods for
seaming 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.
3.4.6.2 Solvent "welding"
Solvent "welding" of thermoplastic sheetings can be achieved by coating the
mating surfaces of the sheetings with a suitable solvent for the compound
and then pressing the two surfaces together firmly by wiping or rolling.
The solvent, which solubilizes the surface of the sheeting and imparts some
tack, can be applied either by a brush or with a squeeze bottle. Initial
set-up time ranges from five minutes to an hour, depending on the type of
material and environmental conditions. A few days are usually needed before
the solvent evaporates completely from the joint and the seams achieve full
strength. Because the technique requires a solvent which can dissolve the
lining material itself, and because crosslinked polymers swell but do not
dissolve, this technique can be used only with thermoplastic materials.
Though this method can be used both in the field and in the factory, it is
sensitive to the weather conditions in which it is used, e.g. temperature,
humidity, and wind. Volatile solvents which may be desirable at lower tem-
peratures will evaporate' too quickly at higner temperatures or may fail to
bond because of moisture condensation under humid conditions.
3.4.6.3 Bodied solvents
Similar to solvent "welding" is the use of bodied solvents to seam lining
materials. A bodied solvent is essentially an adhesive based upon a solution
of the liner compound to be seamed. ..The adhesive needs to be applied to both
surfaces and the two surfaces pressed together after becoming tacky. There
should not be evidence of surface "skinning" or drying of the adhesive
when the two surfaces are joined. The basic advantage of a bodied solvent
97
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over a straight solvent is the increased viscosity of the solution which
allows more control of the evaporation of the adhesive and aids in making
seams on a slope. As with solvent "welding", this tecnhique can only be used
with thermoplastic materials that can be dissolved in a suitable solvent.
This technique can be used to seam sheeting in the factory and is particu-
larly useful in the field.
3.4.6.4 Solvent cements and contact cements
"Solvent cements" is an expression used by the adhesive industry to refer 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 volatization 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.
Surfaces to be bonded by the second :ype 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 sheet-
ings that are to bonded and allowed to dry to a "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.
The adhesives used with the PVC primary test specimens are described as
contact cements. The adhesive used with the neoprene buried test specimen
could also be classified as contact cement.
All solvent cements can be used either in the field or in the factory,
although with a thermoplastic material it would more likely be used in the
field.
3.4.6.5 Vulcanizing adhesives
Vulcanizing adhesives achieve their strength from the- crosslinking or vul-
canization of the polymeric base. The vulcanization 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.
99
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3.4.6.6 Tapes
Tapes have been used to seam membrane lining materials 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 tie surfaces to be joined. Tapes can be used
to hold the sheetings in place *hile another seaming technique is used, or
they can be used to provide the permanent bond.
Tapes have been used to seam polyethylene liners in the field; however, the
use of tapes alone for making seams of liners for waste disposal facilities is
not recommended..
3.4.6.7. Thermal techniques
A number of different techniques Jtilizing heat can be used in the factory or
in the field. The surfaces to be seamed are melted and pressed together to
form a homogeneous bond. One technique works by directing high temperature
air between two sheets in an overlap seam followed by a pressure system.
Another variant of heat seaming is dielectric seaming, which is a factory
process involving the use of high-frequency dielectric equipment to generate
heat and pressure on an overlap seam joint.
3.4.6.8 Welding or fusion methods
Some seaming of HOPE liners are being performed in the field with proprietary
equiment which extrudes HOPE of the same composition as the liner either
between the two sheetings being seamed or at the edge of one sheet to form a
bead. Also, seaming equipment based upon heat guns has been devised in which
coiled plastic welding rods are incorporated. The rod is fed to the seam area
to form a welded seam. In the first welding procedure, a jet of not air
i's 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 material identical
to that of the sheet is injected into the overlap through an extruder nozzle.
A roller moving behind the extruder nozzle presses the overlap together so the
sheets will be fused together by the extruded ribbon of molten material. The
result is a homogeneous weld that is immediately loadbearing. Welding can be
carried out in ambient temperatures between 5°C to 35°C.
3.5 SPRAYED-ON LININGS
3.5.1 Introduction
Liners for disposal impoundments can potentially be formed in the field by
spraying onto a prepared surface a liquid which then solidifies to form a
continuous membrane. - Such liners have been used in water control and im-
poundment, e.g. for canals, small reservoirs, and ponds. Most of the exper-
ience with this type of liner has been with air blown asphalt; however, a
variety of new materials are becoming available which have been used in small
water control installations. Sprayed-on liners are seam-free, but preparing
them pinhole-free in the field may pose serious difficulties. Furthermore,
most of the spray-on materials that have been considered are thermoplastic and
100
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are of low molecular weight, e.g. asphalt, and may interact adversely with
many wastes. Some of the new materials that are being introduced are of high
molecular weight or contain polymeric additives which improve their dura-
bility.
In this section, the following materials are discussed; airblown asphalt,
emulsified asphalt, urethane modified asphalt, and rubber and plastics, in
either liquid or latex form.
3.5.2 Air-blown Asphalt
Membranes of catalytically-blown asphalt are the most commonly used sprayed-on
linings. The asphalts used in making these membrane linings have high soften-
ing points 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 phos-
phorous pentoxide or ferric chloride. To prepare the membrane, the asphalt is
sprayed on a prepared soil surface at a temperature of 400°F, at a pressure of
50 psi through a slot-type nozzle, and at a rate of 1.5 gal yd"' (Bureau of
Reclamation, 1963, p. 80). The finished liner is usually 0.25 inch thick
(Bureau of Reclamation, 1963, p. 79), 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 membranes
retain their tough flexible qualities indefinitely when properly covered and
protected from mechanical damage (Asphalt Institute, 1976). The actual
placing of the earth covers on a sprayed-on membrane may cause some damage to
its integrity.
Studies have shown the addition of 3-5% rubber improves the properties 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).
Bituminous seals are used tfn asphalt concrete, portland cement concrete, soil
asphalt, or soil cement linings to close pores, thus improving waterproofing
or when there may be a reaction between the stored liquid and the lining. The
two types of seals usually applied are:
a. An asphalt cement sprayed over the surface about one qt yd"^
to form a membrane about 0.04 in. thick.
b. An asphalt mastic containing 25 - 50% asphaVt cement, the rest
being a mineral filler, squeegeed on at 5 - 10 Ib yd'S
Installation of sprayed-on asphaltic membranes is usually done- 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 membrane support (Bureau of Reclamation,
1963, p. 81). Covering protects the membrane from most mechanical damage.
A special deep penetration formula of liquid cutback asphalt was applied over
natural-on-site soil at a rate of two gal yd~2. The seepage rate, in this
101
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case, was reduced from 15.9 to 6.14 ft3 ft"2 yr"1 (Day, 1970, p. 20).
Another formulation of cationic asphalt, incorporating white gasoline and
water, penetrated 3/16 to 3/8 inch into the soil. This proved to be inade-
quate for complete sealing (Bureau of Reclamation, 1963, p. 115). A special
cationic asphalt emulsion forms a highly impermeable seal at the soil inter-
face through the attraction of the positively charged asphalt droplets to the
negatively charged soil particles as the emulsion penetrates the substrate.
As little as 15 fluid oz ft"2 results in almost zero seepage. This product
has been used mainly in reservoirs and ponds (Wren, 1973).
Field data on a hot asphalt membrane lining in a canal lateral was obtained
after 11 years of service. The seepage rate at this time was 0.08 ft3/ft2/
day. The seepage rate prior to placement of the liner was 9.9 ft3/ft2/day.
Ninety percent of the aging occurred during the first four years of membrane
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 membrane canal
lining should last beyond 12 years.
Styron and Fry (1979) used an AC-40 grade asphalt cement as a lining material
in tests with two flue gas desil furization (FGU) sludges. A base of silty
sand was compacted to six inches depth and cured at 78°F and 50% humidity for
two to three days. The asphalt liner was then sprayed on the base at a rate
of 0.75 gal yd~s After one year, under a pressure head of five feet of
water, no liquid had passed through the liner. Specifications for AC-40
require a viscosity of 4000+800 poises at 140°F (60°C) and a minimum penetra-
tion of 20. This asphalt requi ~es temperatures of 300 - 400°F for spraying
(Klym and Dodd, 1974).
Except for resistance to hydrocarbon solvents, oils, and fats, the chemical
resistance of asphaltic liners is, in general, good. Asphaltic membranes are
resistant to methyl and ethyl alcohols, glycols, mineral acids other than
nitric acid (at moderate temperatures and concentrations), mineral salts,
alkalis to about 30% concentration, and corrosive gases such as HgS and
SO?- Asphaltic liners exhibit variable to poor performance when exposed to
hydrogen halide vapors, but are essentially impermeable to water (Nat'1.. Assn.
Corr. Eng., 1966). Preparing pinhole-free membranes on large areas by spray-
ing techniques, particularly when hot materials must be sprayed, poses a
variety of problems which are discussed in Section 5.5.
3.5.3 Membranes of Emulsified Asphalt
Emulsions of asphalt in water can be sprayed at ambient temperatures (above
freezing), to form continuous membranes of asphalt after breaking of the
emulsion and evaporation of the water. The membranes are less tough and have
lower softening points than membranes of hot applied catalytically-blown
asphalt. Toughness and dimensional stability can be achieved by spraying
asphalt emulsions onto a supporting fabric. Faorics 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
102 ,
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fabric are often sewn with portable sewing machines after the fabric is
placed (Phillips Petroleum, 1972).
3.5.4 Urethane Modified Asphalt
A urethane modified asphalt liner system is being marketed. It is gen-
erally 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
final membrane is generally recommended to have a thickness of 50 mil,
usually obtained by applying one coat of 0.28 gal yd~2 on horizontal sur-
faces or two coats on vertical surfaces. The second coat may be applied
about 15 minutes after the first coat. The membrane 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 snould be filled. Generally, a primer and a
bonding agent are applied prior to the application of the actual membrane.
The procedures for several base surfaces and the necessary precautions are
provided by the manufacturer (Chevron, 1980).
3.5.5 Rubber and Plastic Latexes
Rubber and resin latexes have also been studied as spray-on liners. Gulf
South Research Institute studied two synthetic latexes. The first was an
experimental styrene polymer, which had a 50% solids content with a high
concentration of wetting agents. The spray was allowed to soak into the
soil and dry. The result was a fairly resilient film with good soil sealing
capabilities. The second latex was an off-grade polyvinylidene chloride. It
also had a 50% solids content and was used as a vapor barrier on air strips.
It formed a film on the soil surface and was reported to provide a good seal
at high pressures (Wren, 1973).
3.6 SOIL SEALANTS
The permeability of-some soils can be significantly reduced by the application
of various chemicals or latexes. They may be waterborne, mixed in place,
spray applied, or injected below the soil surface (Gooding et al, 1967; Jones,
1971). Water borne or spray-on polymer soil sealants can reduce permeability
of earth lined impoundments. However, the sealing effect is confined to the
upper few centimeters and can be significantly diminished by the effects of
wet-dry and/or freeze thaw cycles. Types of sealants include resinous poly-
mer-diesel fuel mixtures, petroleum based emulsions, powdered polymers which
form gels, and monovalent cationic salts (Bureau of Reclamation, 1963, p.
115). See Table 3-9 for a list of representative soil sealants.
Soil sealants utilizing monovalent cations,, mainly sodium salts, chemically
reduce the effective porosity of the soil for flow by replacing the multi-
valent cations in the clay structure. This exchange renders the cluster-
ed soil particles more easily dispersed (Willson, 1966). Sodium carbonate
103
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applied at a rate of two Ib yd"2 provided a seepage reduction of greater
than 90% in Bureau of Reclamation tests. The seepage reduction was still 80%
after removal of the top six inches of soil. Sodium pyrophosphate and sodium
silicate are also potential soil sealants. Soil treated with sodium silicate
and sulfuric acid prior to compaction showed a significant seepage reduction
and is compatible with sulfuric acid bearing wastes (Clark and Moyer, 1974,
P. 13).
Some powdered polymers can form gelatinous masses which tend to fill the
soil voids, thus effecting a surface seal. bome early studies showed that
this surface seal is easily damaged by a water spray, indicating that durabil-
ity tests should be made when considering this type of liner (Willson, 1966).
A powdered mixture of carboxymethyl cellulose and alum (0.25 CMC + 0.05% alum
by wt of dry soil) was mixed with the soil and compacted to a six-inch thick-
ness in one project. The seepage was reduced only slightly from 16 to 14
ft3 ft"2 yr"* (Day, 1970, p. 21). Soil sealants based on polymers are gen-
erally mixtures of swellable linear and crosslinked polymers of approximately
the same molecular weight. The linear portion sorbs to the soil, forming a
flexible network. The crosslinked polymer particles can flow, and thus can
conform to and permeate the soil pores. The formulation depends on the
application. The polymer is usually mixed in a low pH water/ acid solution
and sprayed onto an unfilled site as a l.ow viscosity slurry. The low pH
allows the slurry to penetrate the surface and form a deeper seal.
Polymeric soil sealants niay be applied as a dry blend which is mixed into the
soil and compacted, sprayed on as a slurry, or dusted on as a powder. Highway
construction equipment may be used for dry blending. Water hauling trucks
equipped with centrifugal pumps, hoses, and adjustable fire nozzles have been
successfully used to spray-apply polymer slurries. Any equipment suitable for
dispersing a powder may be used for dusting with a polymer powder.
Dry blending forms the most effective seal and adds some structural strength
to the impoundment. Other factors influencing the .effectiveness of the seal
are the degree of soil compaction and the composition of the impounded fluid.
The limitations of the polymer seals are: the polymer itself does.not supply
strength, the site must be compacted; exposure to salts, acids, and multi-
valent cations causes the polymers to shrink, increasing the permeability and
decreasing the effectiveness of the seal (Parks and Rosene, 1971).
Uniroyal (1972) conducted a study to test the feasibility of using latex as a
soil sealant to prevent seepage into subterranean abandoned mines. In gen-
eral, the field tests confirmed laboratory findings that latex does reduce the
permeability of the soil to water, but the latex is subject to damage by
microbiological attack, frost, and vegetation.
3.7 CHEMICAL ABSORPTIVE LINERS
The use of chemical absorptive liners is a new and promising concept in the
1'ining of waste disposal facilities. This type of liner functions primarily
by removing pollutants from the liquid waste as it passes through the liner
105
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mass. Chan et al (1978) tested several clays and minerals, acidic and basic
fly ash, bottom ash, activated alumina, and activated charcoal as potential^
chemical liners for calcium fluoride, metal finishing, and petroleum sludges.™
The tests were done under flow through conditions, mixing the sorbent with
sand when necessary to achieve the required permeability. None of the sub-
stances alone adequately removed the hazardous or polluting compounds.
However, combinations of sorbents, in a predetermined sequence, do satis-
factorily remove contaminants. The type, sequence, and behavior of the sor-
bents varies with pH and the nature of the waste to be treated. For example,
some materials remove certain metals or organics more effectively than others.
The same sorbent, such as fly ash, may release ions in one pH range and absorb.
ions in another. Flow and non'H owing conditions also affect the absorption
capacities of a material. This concept shows promise, but further testing is
necessary under nonflow conditions with specific wastes to evaluate the
effectiveness of various sorbents in applied situations (Chan et al,1978).
A test is underway of three chemisorptive lining materials, i.e. fly ash,
limestone, and hydrous oxides of iron to assess the attenuation of heavy
metals from two electroplating sludges (Phung et al , 1982). Based on the
analyses of the leachates, results after about three years of exposure were
inconclusive. The latter two materials were suggested by Fuller (1981) who
indicated that they would be potentially useful as liners for metallic leach-
ate constituents.
106
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Chapter 3 - Lining Materials and Lining Technology
i
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Gooding, W. T., Jr., A. D. Bergmann, and C. G. Vinson. 1967. Feasibility
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Goodyear Tire and Rubber Co. 1973. Pond and Pit Liner Materials. 1004-1/73.
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Haxo, H. E." 1981. Testing of Materials for Use in Lining Waste Disposal
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R. A. Conway and B. C. Malloy. ASTM Special Technical Publication 760.
American Society for Testing and Materials, Hniladelphia, PA.
Haxo, H. E,, R. S. Haxo, and R. M. White. 1977. Liner Materials Exposed to
Hazardous and Toxic Sludges - First Interim Report. EPA-600/2-77-081 .
U. S. Environmental Protection Agency, Cincinnati, OH. 63 pp.
Haxo, H. E., and R. M. White. 1976. Evaluation of Liner Materials Exposed to
Leachate - Second Interim Report. EPA-600/2-76-255. U. S. Environmental
Protection Agency, Cincinnati, OH. 53 pp.
Haxo, H. E., R. M. White, P. 0. Haxo, and M. A. Fong. 1982. Liner Materials
Exposed to Municipal Solid Waste Leachate - Final Report. Contract No.
68-03-2134. In Press. U. S. Environmental Protection Agency, Cincinnati,
OH. 170 pp.
Hickey, M. E. 1969. Investigation of Plastic Films for Canal Linings.
Research Report No. 19. Bureau of Reclamation, U. S. Dept. of the
Interior, Washington, DC. 35 pp.
Hickey, M. E. 1971. Synthetic Rubber Canal Linings. REC-ERC-71-22. Bureau
of Reclamation, U. S. Dept. of the Interior, DC. 34 pp.
Hinkle, 0. 1976. Impermeable Asphalt Concrete Pond Liner. (IS-166).
Reprinted from Civil- Engineering - ASCE. Asphalt Institute, College
Park, MD. 4 pp.
Hofmann, U., A. Weiss, G. Koch, A. Mehler, and A. Scholz. 1956. Intra-
crystalline Swelling, Cation Exchange, and Anion Exchange of Minerals of
the Montmorillonite Group of Kaolinite. Nat. Acad. Sci. Pub. 456. pp.
273-87.
Holtz, W. G., and M. J. Gibbs. 1956. Engineering Properties of Expansive
days. Am. Soc. Civ. Eng. Trans. 121:641-677.
Hughes, J. 1977. A Method for the Evaluation of Bentonites as Soil Sealants
for the Control of Highly Contaminated Industrial Wastes. Purdue Indus-
trial Waste Conference 32: 814-819. " '
Jonansen, R. T. and H. N. Dunning. 1959. Water Vapor Absorption on Clays.
In: Proc. 6th Nat. Clay Conf. Pergamon Press, NY. . pp. 249-258.
109
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Jones, C. W. 1971. Laboratory Evaluation of Canal Soil Sealants. REC-
ERC-71-1. Bureau of Reclamation, Denver, CO. 17 pp.
Kays, W. B. 1977. Construction of Linings for Reservoirs, Tanks, and Pollu-
tion Control Facilities. Wiley Interscience - Jonn Wiley and Sons, NY.
379 pp.
Ke, B. 1971. Differential Thermal Analysis. In: Encycl. Polymer Sci.
Tecnnol. Vol 5, pp 37-65.
Kirkham, D. and W. L. Powers. 1972. Advanced Soil Physics. Interscience,
John Wiley and Sons, Inc. 534 pp.
Klym, T., and 0. Dodd. 1974. Landfill Disposal of Scrubber Sludge. Present-
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Lambe, T. W. 1958. The Structure of Compacted Clay. J. Soil Mech. Found.
Div. Am. Soc. Civ. Eng. 84(SM2):34: Paper 1654.
Lambe, T. W. and R. V. Whitman. 1979. Soil Mechanics, SI Version. John
Wiley and Sons, NY. 553 pp.
Lee, J. 1974. Selecting Membrane Pond Liners. Pollution Engineering.
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Lowell, Philip S. 1975. In reference EPRI. 1975.
Lutz, J. F., and W. D. Kemper. 1959. Intrinsic Permeability of Clay as
Affected by Clay-Water Interaction. Soil Sci. 88:83-90.
McDowell, C. 1946. Progress Report on Development and Use of Strength Tests
for Subgrade Soils and Flexible Base Materials. In: Proc. the Highway
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Marshall, C. E. 1964. The Physical Chemistry and Minerology of Soils. Vol
1. John Wiley and Sons, Inc., NY.
McFadden, W. 19'78. Techniques of Combined GC/MS - Applications in Organic
Analysis. John Wiley and Sons, NY.
Meade, R. H. 1964. Removal of Water and Rearrangement of Particles During
the Compaction of Clayey Sediments - Review. U. S. Geological Survey
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Middlebrooks, E. J., C. Perman, and I. Dunn. 1978. Wastewater Stabilization
Pond Linings. Special Report 78-28. Cold Regions Research and Engineer-
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Mielenz, R. C., and M. E. King. 1955. Physical-Chemical Properties and
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Mitchell, 0. K. 1956. The Fabric of Natural Clays and its Relation to
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Mitchell, J. K. 1976. Fundamentals of Soil Behavior. John Wiley and Sons,
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Mitchell, J. K., D. R.- Hooper, and R. G. Campanella. 1965. Permeability
of Compacted Clay. J. Soil Mech. Found. Div. Am. Soc. Civ. Eng. 91(SM4):
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of Asphalt Coatings. Mater. Protect. 5:81-83.
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113
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CHAPTER 4
LINING MATERIALS IN SERVICE-TYPE ENVIRONMENTS
4.1 INTRODUCTION
In Chapter 2, different types of wastes that are or may be destined for land
disposal are discussed with emphasis on their potential effects upon the
integrity of liners. In Chapter 3, materials which might be used for lining
waste storage and disposal impoundments are described and their characteris-
tics discussed. In this chapter,, we discuss the effects upon lining mater-
ials of exposure to different wastes and the interaction of liners and wastes
that might exist in service-type environments. Some field service results
are also reported.
The durability and service life of a given liner in a waste impoundment
depends to a great extent upon the specific liquids which contact the liner
from the time it is originally placed. The liquid emanating from waste can be
highly complex at a given time and can continually change in composition with
time even in a given impoundment. Consequently, an important consideration
in the operation of a disposal facility is that measures should be taken to
minimize the variation in the character of the waste, as there is no single
lining material which can resist all wastes.
Potential liner materials can vary greatly in chemical composition from
compacted soils and clays to highly crystalline polymeric materials which are
highly chemically resistant and have very low permeability. Similarly, the
wastes, as indicated in the discussion in Chapter 2, can vary from highly
polar solvents, such as water, through highly nonpolar materials, such as
lubricating oils and hydrocarbon solven-ts. Most wastes probably contain
water as the principal carrier, though wastes of high organic content can
also be encountered, such as those in drums. All compounds, either inorganic
or organic, are, to a certain degree, soluble in water; consequently, con-
taminants or pollutants can be carried in the water,. Also, many solvents can
be totally miscible with water. The complexity of wastes can result in
combined effects with respect to mary of the liners.
Dissolved organic constituents in the leachate, even in minor amounts, can
preferentially combine with organic: liner materials and may, over extended
periods of time, cause the failure of a liner based upon organic materials
such as asphalt and polymeric materials. There are indications now that
some organic waste liquids can also have major adverse effects on some soils
and clays, as discussed later in this Chapter. Considerable information
exists regarding water resistance of materials of which linings are made,
regardless of whether they are soils, asphalts, or polymeric membranes.
114
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Waste liquids, though most contain water and many dissolved ingredients, have
different effects upon lining materials. The pollutants, which liners are
designed to prevent from entering the groundwater at concentrations greater
than allowed by regulation, may not themselves be aggressive toward liners.
All constituents in a waste, as well as the liner composition, should be
considered in assessing a liner material for a given impoundment.
A.lthough there is much information on the effects of water on lining materi-
als, no similar body of information exists on the effects on lining materials
of chemicals and other liquids which might be found in the waste streams
produced by various industries. On the other hand, considerable information
is available on the effects of different chemicals and relatively simple
mixtures of chemicals upon many polymeric materials that are used as con-
tainers, tank linings, pipe linings, and gaskets in direct contact with
chemicals, solvents, and oils; however, these polymers are selected and
compounded for the specific application. Consequently, the EPA undertook
several research programs to study the effects of waste liquids and chemicals
on lining materials:
Sanitary Landfill Leacnate (Haxo, 1973-1981).
Hazardous Wastes (Haxo, 1975-1982).
Flue Gas Desulfurization Sludges (Styron and Fry, 1979).
State-of-the-art Study of Liners (Stewart, Iy78).
Field Verification of Liners (Pacey and Haxo, 1980).
Effect of Organic Chemicals and Solvents on the Permeability of
Clay Soils (Brown, Anderson, Green, ongoing).
4.2 THE EFFECTS OF WASTE LIQUIDS ON CLAY SOILS
4.2.1 introduction
In Chapter 3, the general properties and characteristics of soils were
discussed considering water as the liquid with which the soils would be in
contact. Such properties as permeability, Atterberg limits, and strength are
measured using water as the permeant or the test liquid. However, changing
of the liquid or dissolving of either inorganic or organic constituents in
the water can drastically change many of the properties of soils. The effect
upon soil permeability is of particular importance if it is used as a liner
for waste storage and impoundment facities.
Because permeability is the essential property that should be considered
in the case of a soil liner, any a1terations~of a soil due to the presence of
a waste-leachate should be identified. The most relevant characteristics
which can alter soil flow properties are:
i 115
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a. The dispersing/flocculating tendencies of the soil when contacted by
the waste-!iquid.
b. The alterations in the shrink/swell properties of the soil.
c. The change of pore-size distribution characteristics.
d. The dissolution/precipitation of chemical species, thus inducing an
alteration of the proportion of soil volume available for flow.
e. The modification of the adsorption properties of the soils.
Interactions between clays or clay soils and waste leachates that may impact
the permeability of the clay liner or stability of the clay sidewalls to a
disposal site are discussed in this chapter. These are discussed under
failure mechanisms. Results of a study by Brown and Anderson (1982) on the
effects of pure organic chemicals; and solvents on the permeability of several
clay soils are presented.
4.2.2 Failure Mechanisms in Clay-Soil Liners
Failure mechanisms of clay liner:; are defined in this document as any inter-
action between waste liquids and compacted clay soil that can substantially
increase the overall permeability of a clay liner and cause the liner not to
meet the design requirements.
There are a variety of other mechanisms by which a clay-soil-lined landfill
or waste impoundment can fail to prevent the escape of waste leachates.
Seismic activity or subsidence can cause loss of the structural integrity of
a liner. Tree roots, digging animals, or building activities may damage a
landfill cover and allow the escape of volatile wastes. Various environr
mental conditions can affect the stability and strength of clay sidewall
slopes, which may allow the lateral movement of *aste leachates. There are
still many unknowns with regard to waste containment. While there are a
variety of failure mechanisms that can cause clay liners to leak excessively,
this section deals with effects on the permeability of clay liners caused by
interactions with waste liquids.
Increases in the permeability of a compacted clay liner due to waste liquids
are usually associated with a shift in the pore size distribution toward more
macropores. Climatological cycles (such as wetting and drying, freezing and
thawing, percolating rainfall that dissolves soluble soil -components, etc)
are widely understood to be responsible for the development of large pores
and permeability increases in undisturbed clay soils (Brewer, 1964; Brady,
1974). These natural processes can be greatly accelerated in the context of
a remolded and compacted clay soil, exposed to waste leachates.
4.2.2.1 Increase in permeability throughout the soil liner
due to volume changes. •-•••
Volume changes of a soil liner during service may occur if the equilibrium
swell/shrink of the soil/water system is affected when water is replaced by
the waste effluent.
116
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Upon water replacement, the volume of individual clay particles changes, if
the clay is non-kaolinitic. This happens because a clay particle is a porous
micro-soil body, with a porosity fundamentally different from the one char-
acteristic for the bulk soil. Due to its crystalline nature, the clay
particle displays an orderly porosity, i.e. the space is represented by
void regions, oriented parallel and intercalating the solid 2:1 matrix of the
clay mineral. Thus, in a wet condition every 2:1 crystalline layer is
separated from its two neighbors by two pore regions saturated with the
particular liquid. The distance between the centers of two neighboring 2:1
crystalline layers separated by the interlayer liquid film is called "inter-
layer spacing" and is determined with x-ray diffraction analysis.
The interlayer spacing is a characteristic of a particular soil/liquid system
depending on the clay mineralogy, the nature of the dominant adsorbed cation,
and the properties of the saturating liquid.
Between two neighboring 2:1 layers, several forces operate. They have been
traditionally discussed and grouped as attractive and repulsive forces.
The attractive forces are the van der Waals (fluctuating dipole bonds) and
the London attracting energy forces. It is generally accepted that values
of these attractive forces at a given distance from a 2:1 layer do not vary
significantly with changes in environmental context, i.e. liquid charac-
teristics.
The repulsive forces, on the other hand, are very sensitive to the environ-
mental conditions and are strongly affected, particularly by the electrolyte
concentrations, dielectric constant, and the dipole moment of the liquid
present in the interlayer space.
The electrolyte concentration and the nature of the dominant cation in the
liq'uid are very efficient in controlling the interlayer spacing, particularly
in the case of some members of the smectite group clays. Thus, due to its
large hydrated radius, Na-cation results in an almost unrestricted penetra-
tion of water inside the clay particle at which stage the water layers are
several times the thickness of the 2:1 layer (Theng, 1973).
The effect of salt concentration on interlayer spacing of smectites was
Studied among others by Weiss (1958). While the distilled water and the
0.01N NaCl solution resu-lted in an infinite interlayer spacing, the 1,3, and
5N NaCl solutions yielded spacings of 1.92, 1.60, and less than 1.57 nm,
respectively. At spacings below 1.5 nm, the repulsive forces are considered
to be much smaller than the attractive forces (Yong and Warkentin, 1975) and
the clay tends to flocculate.
Similar to the previously described situation when mineral species were dis-
solved in water, organic compounds and their concentrations also affect
interlayer spacing. It has been shown by Greene-Kelly (1955) that the
Slightly basic aromatic compound, aniline, adsorbed with aromatic rings par-
al'le" to the clay surface at low concentrations (0.62 meq/gm clay) resulting
117
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in low interlayer spacing (1.42' nm), while a concentration of 0.91 meq/gm
resulted in a larger spacing equal to 1.78 nm due to the positioning of
aromatic rings perpendicular to the 2:1 clay layers.
It has been previously stated that the interlayer spacing is affected by the
dielectric constant of the liquid present in the soil. The theory of dielec-
tric constant has been thoroughly explained by Bockris and Reddy (1970).
The dielectric constant of a liquid is its ability to transmit electrical
charge. When the original water solution of the soil is replaced by an
organic compound with a lower dielectric constant, the fluid film surrounding"
and present inside the clay particles must be thinner for the negative
surface charge to be neutralized by the cations. Thus, the lower the dielec-
tric constant of the replacing liquid, the smaller the interlayer spacing.
According to the double-layer theory, the "half-distance", which is a measure
of interlayer spacing, is proportional to the dielectric constant raised to
the power 0.5.
Table 4-1 illustrates the relationship between dielectric constant and
interlayer spacing. The presented data do not prove the validity of the
square root relationship. It appears that the relationship is affected by
other significant factors, among which are the dipole moment (Barshad, 1952),
the nature of the adsorbed clay (Bissada et al , 1967), the degree of methyl
substitution on the organic molecule (Olejnik et al , 1970), and ion-dipole
interactions (Czarnecka and Gillott, 1980). All facts considered, however,
the smaller the dielectric constant the smaller the interlayer spacing, which
is illustrated by Barshad's (1952) results presented in Table 4-2.
TABLE 4-1. INTERLAYER SPACING OF CALCIUM SMECTITE
AS A FUNCTION OF DIELECTRIC CONSTANT AND DIPOLE MOMENT3
Interlayer
spacing, nm
0.99
0.99
1.45
1.70
1.71
1.73
1.92
Sorbed
fluid
Benzene
Paraffin
Butanol
Ethanol
Methanol
Methyl ethyl
ketone
Water
Dipole
moment
0
0
1.6
1.7
1.6
2.7
1.-8 -
- Dielectric
constant
2.3
2.1
17.7
25.0
32.4
18.9
78.5
Source: Barsha a .
3A11 samples were dehydrated at 250°C prior to immer-
sion in the test fluid.
118
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TABLE 4-2
INTERLAYER SPACING OF CALCIUM SMECTITE3 IMMERSED
IN LIQUIDS OF VARIOUS DIELECTRIC CONSTANTSA
Immersion liquid
100:0 Water:propanol
70:30 Water:propanol
40:60 Water:propanol
30:70 Water:propanol
20:80 Water:propanol
10:90 Water:propanol
0:100 Water:propanol
100:0 Water.-glycerol
40:60 Water:glycerol
0:100 Water:glycerol
Dielectric
constant
(25°C)
78.5
57.7
36.4
30.7
26.1
22.7
20.1
78.5
59.4
39.2
Interlayer
spacing
(mn)
1.92
1.88
1.84
1.77
1.77
1.52
1.44
1.92
1.79
1.68
aDehydrated at 250°C prior to immersion in liq-
uid.
bModified from Barshad (1952).
The interlayer spacing is an important clay characteristic because it con-
trols the bulk volume change behavior of a soil. These bulk characteristics
are identified in geotechnical investigation by determining the total swell,
swelling pressure, shrinkage limit, and other soil characteristics which-are
closely related to swell and shrink, such as clay content, Atterberg Limits,
or clay activity. When a clay soil compacted as a soil liner is permeated by
a liquid with different charecteristies compared to water, changes in inter-
layer spacing occur. For example, if the water is replaced by an organic
compound with a lower dielectric constant, the individual clay particles will
contract as a result of a thinner interlayer spacing and thus an additional
pore space will become available for clay particles to
i.e. to flocculate. This regrouping and reorientation of
result in a decrease of void ratio, but most significantly
change of the original pore-size distribution toward a
larger pores. The consequence will be a greater permeability, but whether
this permeability value will be greater than the designed value cannot be
inferred a priori. This is the principal reason why testing of permeability
of the soil to both water and the waste liquid is required, particularly when
there is reason to believe that the waste liquid has a chemical composition or
physical properties substantially different from water and thus differences in
permeability are likely to occur.
orient themselves,
clay particles may
should result in a
distribution with
119
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The above described failure mechanism should normally occur throughout the
whole soil liner where replacement by the waste fluid and the exposure time
are of the same order of magnitude for different points in the liner.
In this discussion on volume-change characteristics of a soil, it was tacitly
assumed that the greater the tencency of a soil to change its volume, the more
drastic the changes in flow-properties can be expected. While this seems to
be a logical conclusion, the quantification of such a statement is lacking
at the present: time, but it is certainly true for the case in which the
original soil solution is changed in the long run by the waste-liquid. In the
general swelling of a soil, an increase in void ratio should increase soil
permeability since a larger proportion of the total soils volume is available
for flow. In our particular situation, this may very well not be the case,
because simultaneously with the volume increase, a change in pore size dis-
tribution will occur and with it a decrease in the median pore size of the
soil. This latter effect can easily offset the volume increase tendency of
the soil and thus result in a lower permeability of the soil.
Ideally, a soil specimen should be treated with the waste-liquid in a real-
istic way, its mechanical behavior observed, and any alterations in flow
properties recorded. The final argument for using a particular soil as a
liner (apart from its attenuating capacity) is its resistance to the flow of
waste effluent into underlying, urdisturbed soil.
4.2.2.2 Dissolution of clay
Dissolution of a clay liner can be brought about by an infiltrating chemical
that dissolves the exposed surfaces of a pore or channel. Either organic or
inorganic acids or bases may solubilize portions of the clay structure. Acids
have been reported to solubilize aluminum, iron, alkali metals and alkaline
earths while bases will dissolve silica (Grim, 1953). Since clay minerals
contain both silica and aluminum ;n large quantities, they are susceptible to
partial dissolution by either acids or bases.
Pask et al (194i5) boiled several clay minerals in acid and found the percent
solubilization of alumina was 3% from kaolinite, 11% from illite, and greater.
than 33%- from montmori1lonite. Grim (1968) found the solubility of clays in
acid "varies with the nature of the acid, the acid concentration, the acid-
to-clay ratio; the temperature and the duration of treatment." He also found
that the action of an acid on clay was enhanced when the acid had an anion
about the same size and geometry as a clay component. This would permit even
weak acids, e.g. organic acids, to dissolve clays under some conditions.
Hurst (1970) found that the permeability of geologic formations could be
increased by pumping in acetic or formic acid. Johansen et al. (1951) re-
ported flow increases for water wells following their treatment with a solu-
tion containing .citric acid. Grubbs et al. (1972) found acid waste as the
probable causal agent in the permeability increase of carbonate-containing
minerals. X-ray diffraction studies of the four clay minerals injected with
acid waste showed them to be dissolved or completely altered. Diffraction
peaks showed the most variability with montmorillonite clays.
120
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Acidization is the name used for the process of permeability increase by acid
mineral dissolution. This process is widely used to increase the permeabil-
ity and hence the productivity of oil wells (Sinex, 1970).
An ever present source of organic acids in waste impoundments is anaerobic
decomposition by-products. These include acetic,- propionic, butyric, iso-
butyric and lactic acid. Anaerobic decomposition will yield the carboxylic
acid derivatives of whatever organic fluids are placed in the impoundment.
Material that encrusts at the base of wells used to inject waste usually
consists of calcium, magnesium and iron carbonates, along with imbedded sand
and clay particles. In order to remove the carbonate compounds, they must be
dissolved and then held in solution against precipitation forces. Dissolu-
tion is usually accomplished with a strong acid. At this point, calcium will
reprecipitate (as calcium sulfate in the presence of sulfuric acid) unless it
is chelated and removed by a flowing fluid. Chelating agents effective at
preventing reprecipitation of various carbonates are citric acid, tartaric
acid, and glycolic acid (Bur. Rec., 1977).
It is well known that strongly alkaline solutions can partially solubilize
silica-containing soil constituents. Nutting (1943) showed even extremely
dilute solutions of alkali to be effective at removing silica from smectites
by dissolution from the crystal lattice.
4.2.2.3 Piping
Underseepage as the result of soil piping is an ever present danger in
earthen dams. Mansur and Kauffman (1956) describe piping as "the active
erosion... pressure and the concentration of seepage in localized channels."
Jones (1978) found the early stages of piping development to be associated
with vertical contrasts of the structure and permeability in soils. Soil
piping was also associated with shifts in a soil pore size distribution
toward macropores with no corresponding change in total porosity. A reactive
fluid may enlarge the surface area of a pore by dissolution of the pore wall
and by the dissolution of the soil matrix between two pores. While a fluid's
reactivity is reduced by its action on the pore wall, the size increase of
the pore will increase the turbulent character of the flow inside the pore
and consequently the erosion power of the moving fluid. In this manner, any
variability in the pore size distribution of a clay liner may be magnified
with time. Schechter and Gridley (1969) found that wormhole formation was
the result of a reactive fluid's preferential flow in larger pores. He went
on to say that a quasi-equi1ibriurn is reached where further growth in a pore
is limited by the rate of diffusion of the reactive fluid.
Seepage by reservoir water into dams has been reported to have caused disper-
sive piping and eventual tunneling all the way through earth dams. Tunneling
was reported to occur in soils with .a l.ocal. ..permeabil ity of 1 x 10"^ cm s~^.
Differential solution and subsequent leaching, especially with calcareous
sediments, was reported to result in the formation of channels, sink holes
121
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and cavities (Mitchell, 1976). In this respect dissolution seems to be in
some circumstances a precondition for piping.
Cedergren (1967) reported that differential leaching of limestone, gypsum and
other water soluble mineral components can lead to development of solution
channels that get larger with time and substantially increase permeability.
He warned not to underestimate the importance of minor soil and geologic
details on the permeability of soil formations as they cause the majority of
failures in dams, reservoirs and other hydraulic structures.
Cedergren (1967) concluded that most failures caused by seepage can be placed
in two categories:
a. Those that are caused by soil particles migrating to an escape
exit, causing piping and erosional failures; and
b. Those caused by uncontrolled seepage patterns which lead to
saturation, internal flooding, and excessive seepage.
Crouch (1978) found that so called tunnels, tunnel-gul1ies, or pseudokarsts
will develop in dispersive soils where the soil-colloid bond strengths are
low compared to the energy of water flowing througn the soil. He found
dispersive soils or those with low structural stability have been associated
with tunnel erosion throughout tire world. Other factors found to be related
to tunnel erosion were ESP (exchangeable sodium percentage), soil cracks, low
permeability, and hydraulic gradients.
In a study of the variables affecting piping, Landau and Altschaeffl (1977)
noted a strong interaction between the chemical composition of the eroding
water and compaction water content. Ion concentration seemed to have little
effect on soil piping susceptibility for mixed illitic and kaolinitic clay
loam compacted dry of optimum. For the same soil compacted wet of optimum,
soil piping susceptibility was highly related to ion concentration in the
eroding water. When low ion concentration eroding water is combined with
wet-of-optimum compaction, Landau and Altschaeffl (1977) reported low
resistance to internal erosion.
Piping involves the slaking of soil particles. Slaking is defined as the
disintegration of unconfined soil samples when submerged in a fluid.
Moriwaki and Mitchell (1977) investigated the dispersive slaking of sodium
and calcium saturated kaolinite, illite, and montmori1lonite. All the clays
slaked by dispersion when saturated with sodium with :he process proceeding
faster with sodium kaolinite and sodium illite. Sodium illite swelled
slightly while dispersion of sodium montmori 1 lonite was preceded by expensive
swelling. Sodium kaolinite underwent no visible swelling while dispersing.
For the calcium saturated clays, illite dispersed much more slowly while the
rate of dispersion .increased for kaolinite and montmorillonite. Calcium
kaolinite was thought to disperse faster because'of its higher permeability
relative to sodium kaolinite. Sodium montmorillonite was thought to disperse
slowly because the large degree of swelling it underwent would lower permea-
bility, thus slowing water entry and retarding dispersion.
122
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Compaction has been shown to decrease the electrolyte content of expelled
interlayer water (Rosenbaum, 1976). Such a lowering of fluid electrolyte
concentrations in sodium-saturated clays may cause substantial swelling and
dispersion (Hardcastle and Mitchell, 1974). This dispersion causes particle
migrations. If there are fluid conducting pores large enough to transport
these dispersed clay particles, permeability increases and soil piping may
result (Aitchison and Wood, 1965).
It is important to note that piping would initiate on the underside of a clay
liner where clay particles could migrate into a substrata with larger pore
diameters. The soil pipe would then progress upward through the clay liner
until it finds an opening into the waste impoundment. Clay particles have
been shown to migrate through porous media containing less than 15% clay
(Hardcastle and Mitchell, 1974). Consequently, clay liners underlain by soils
containing less than 15% clay may be susceptible to soil piping.
Four laboratory tests for the determination of soil susceptibility to dis-
persive erosion have been developed by the U.S. Soil Conservation Service.
A major conclusion of a recent symposium on soil piping was that these four
tests should be performed on soils where piping would cause unacceptable
damage (Sherard and Decker, 1977). The four tests are the pinhole test, a
test of dissolved salts in the pore water, the SCS dipsersion test, and the
crumb test. For the test methods and extensive test data see ASTM Special
Technical Publication No. 623.
4.2.2.4 Slope stability
When the topography of the waste-disposal site is flat, soil strength char-
acteristics are of little consequence. However, environmental and economic
criteria often prevail in the process of choosing a waste disposal site;
environmentally, such a site should be placed as far away as possible from
highly populated areas, and since these are mostly flat areas; the disposal
sites will be pushed into hilly dissected topographical regions; economic-
ally, a hilly region has its advantages in the sense that placing a waste in
a ravine,-for instance, may involve generally less earth work and result in a
higher efficiency of waste-storage per unit disposal area. Consequently, in
many situations, the waste-disposal site floor will be sloping and so will
the soil liner. A similar situation occurs even when the floor of the
waste-disposal site is flat, but the waste is buried under the ground
surface. In this case the waste-disposal "site" will have a trapezoidal
cross section with lateral slopes. The consolidation of the waste during the
storage time can result in uncovering of slopes, relief of lateral pressures,
and possibly an unstable condition. For these situations, an investigation
of stress-strain and strength properties of the soil has to be conducted.
The difficulties associated with the analysis of slope stability are not
associated with the usual difficulty in determining properly the cohesional
and fractional characteristics of the soil, but rather with a proper esti-
mation of the characteristic hydrology of the site under operation condition;
in other words, changes in the hydrology have to be -estimated, average and
"worst" patterns have to be identified, and all information integrated into a
factor of safety using pertinent methods of analysis.
123
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Although slope stability considerations are important, we believe that due to
the vast amount of available information on this subject, the design of the
slope can be done in such a way that a factor of safety larger than 1.4 - 1.5
can be generated. The problem is slightly more complicated when there is a
partial replacement of soil water by waste-leachate; the design of the slope
cannot be done without considering this factor.
In Section 5.2.2.5, the influence of different factors upon soil strength are
presented and suggestions are made regarding the testing of the soils for
strength.
The failure of a sloped soil liner can occur as a slippage of the whole com-
pacted layer over the undisturbec soil or bedrock. Another mechanism is the
creep of very cohesive saturated clays; by this mechanism tension can be gen-
erated in a slope and cracks perpendicular to the slope can enhance failure.
We define all these conditions as "failure", since they will lead to changes
in the integrity of the soil liner with adverse effects upon bulk soil flow-
properties.
4.2.2.5 Miscellaneous
There are a variety of situations that may increase the permeability of clay
liners other than those discussed above. The phenomena causing the perme-
ability increase may not be fully understood, but they are presented here for
their possible usefulness in future research.
Miller et al (1975) found that the permeability of a soil increased as
water flushed out an earlier application of surfactant.
Grubbs et al (1973) found that methyl alcohol increased the permeability of
a core previously injected with oil-base wastes. He also noted the use of
solvents, organic acids, surfactants, alcohols, and emulsion breakers for
permeability enhancement in deep well injection operations.
Letey et al (1962) observed for water-repellent soils an increase in the
infiltration rate with time. 'He felt this was due to the progressive
neutralization of the soils' water repellency as the depth of infiltration
increased. In a later study, Miller et al (1975) found that permeability
increases with time if there is a substance in the soil that would dissolve
into the water and decrease its surface tension.
Watson (1968) found surfactants acted to stabilize soils against dispersion
and swelling, thereby preventing a decrease in permeability values at certain
surfactant concentrations.
Wolstenholme (1977) stated that solvents of low viscosity are "by their very
nature" Teachable and able to extract organic components from otherwise dry
waste. Low viscosity, would significantly increase a fluid's permeability
according to Darcy's Law.
124
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4.2.3 Laboratory Study of the Effects of Different Organic Liquids
on Soil Permeability
4.2.3.1 Introduction
Liquids emanating from wastes were reviewed in Chapter 2. From the stand-
point of soils, they were divided into water and four classes of liquids:
acidic, basic, neutral polar, and neutral nonpolar. In this subsection, data
are presented on the effects organic liquids have on the permeability of clay
soil liners for waste storage and disposal facities. Additionally, the
effects of water on the permeability of clay liners previously permeated
by various organic liquids are discussed.
Some uncertainty exists as to whether clay soil liners would be saturated
and hence permeated by percolating water before the leachate from the dis-
posed waste enters the liner. The degree of clay soil liner presaturation is
dependent on the nature of the disposal facility, the climatic context of the
disposal site, and the design criteria for the liner. If the disposal
facility remains open after construction and during waste placement, it would
act as a bathtub, catching any precipitation that might occur. Some disposal
facilities may maintain clay soil liners in an unsaturated state, such as
those in drier climates prevalent in parts of western and central United
States or that have an effective leachate removal system; however, most
industrial landfills are located in relatively wet climates, such as the Gulf
Coast, Great Lakes, Northwest, Northeast, and Southeast regions of the United
States (EPA 1980a; EPA 1980b). These wetter climates would probably maintain
any buried clay soil near saturation. Another factor that would determine if
a clay liner is presaturated would be the design criteria set out by the
manufacturer of a processed clay if it i's a befltonite liner. In general,
design criteria for bentonite liners suggest the complete presaturation of the
clay to optimize swelling of the clay, thereby obtaining the tightest seal.
The testing of the permeability of clay soils which are candidates for lining
of hazardous waste landfills and surface impoundments has been performed in
the past, using water or a standard aqueous permeant such as 0.01 N calcium
sulfate solution. In.view of the concern of the effects of various liquids
which contain dissolved organic or inorganic constituents and of organic
solvents upon the permeability of clayey soils, Brown and Anderson (1982)
conducted an investigation into the effects of four classes of pure organic
liquids upon the permeability of four selected clay soils. Based upon
laboratory permeameter testing, results to date show that clays that are
satisfactory, as judged by water permeability testing under standard ASTM
test methods, increase drastically in permeability when tested with vari-
ous pure organic chemicals. These clay soils underwent large permeability
increases when permeated with basic neutral polar, neutral nonpolar, or
organic liquids, and showed potential -for substantial permeabi1ity increases
when exposed to concentrated organic acids.
The results of this study indicate the need-to test the permeability of
potential clay liners with the organic liquid that the liner may be expected
to impound. The results of this work is summarized in the following subsec-
tions (Brown and Anderson, 1982).
125
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4.2.3.2 Materials and methods
Four native clay soils, having different mineralogical chemical properties,*
were selected for this study., Two of the soils contained predominantly
smectitic clay minerals having different chemical properties. The other two
soils contained predominantly kaolinitic and illitic clay minerals. Each
soil was characterized by the following:
- A permeability less than 10~7 cm s'l when compacted at optimum
water content.
- A geographic extent of at least one million hectares.
- Deposits thick enough to permit economic excavation for use as clay-
soil liners.
- A minimum content of 35% by weight of clay minerals.
The general properties of these four clay soils are given in Table 4-3.
TABLE 4-3. DESCRIPTIONS OF THE FOUR CLAY SOILS USED IN STUDY
Clay soil
description
% Sand (> 50ym)
% Silt (50-2. Oym)
% Clay (<2.0pm)
Predominant clay
minerals3
Shrink-swell
potential
Corrosivity
(steel )
Cation exchange
capacity (meq/
lOOgms)
Total alkalinity
(meq/lOOgms)
Noncalcareous
smectite
35-37
26-28
36-38
1. Smectite
2. Mica
3.Kaol inite
Very high
High
24.2
3.3
Cal careous
smecite
7-8
42-44
48-50
1. Smectite
2.Kaolinite
Very high
High
36.8
129.2
Mixed cation
kaol inite
39-41
17-18
42
1. Kaol inite
2. Mica
Moderate
High
8.6
0.8
Mixed cation
i 11 i te
14-15
38-39
47
l.Illite
2. Smectite
Moderate
(b)
18.3
4.2
aln order of descending quantity in the soil.
bNot determined.
126
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In preparing the soils for test, the clay soils were first broken into golf
ball-sized clods and then air dried. Each soil was then ground sufficiency to
pass ASTM No. 4 sieve (4.7 mm) and then stored at room temperature in large
drums. The methods used for determining soil properties are described by
Black (1965), except for moisture dejnsity relationships where ASTM test
methods were- used.
General and detailed information on tie four soils can be obtained in the
report by Brown and Anderson (1982). They report soil series and order,
location, geographically and within the solum, and the parent material from
which each soil was derived. Also, they report grain size distribution and
mineralogy, physical properties including permeability, and chemical proper-
ties.
The organic liquids included four classes:
- Organic acids.
- Organic bases.
- Neutral polar organic li
- Neutral nonpolar organic
qui ds.
organi c 1iquids.
as a reference liquid.
gent grades. This is in
The organic
contrast to
Water was also included in the testing
liquids used in this study were all re<
waste liquids which are normally a mixiure of liquids combined with organic
and inorganic solutes. Also, the waste liquids often contain suspended solids
that could clog or coat pores. Relevant chemical and physical properties of
these test liquids are presented in Table 4-4.
Water (0.01 N calcium sulfate) was usec
establish baseline permeability of each
selected due
concentration
ically found
to its stabilizing
was used
in soils.
the report by Anderson et al -(1982).
as a control liquid or permeant to
soil specimen. The calcium salt was
effect! on per-ipabi 1 ity. This particular
because it approximates the salt concentration typ-
Additional details of these liquids can be found in
The procedure used in
for the Permeability
the test is described in Appendix III-C, "Test Method
of Compacted Cla}
Soils (Constant elevated pressure
methods)". The soils were compacted to ?0% Proctor in standard permeameters.
The permeability testing used constant e[levated pressures of either 10 or 60
psi. The tests were started using 0.01 N calcium sulfate solution and, once
steady values were obtained, the solution was replaced with the organic liquid
to be tested. The pressure used with the illite and kaolinitic soils was 10
psi, and 60 psi was used with the two smectitic soils.
4.2.3.3. Experimental results
Water. Permeability of four compacted .clay- soils to a standard test aqueous
liquid or permeant (0.01N CaSO,^) were examined by Anderson et al (1982) and
are presented in Figure 4-1. Permeability values of noncalcareous smectite
and mixed cation kaolinite soils were essentially constant during passage of
127
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TABLE 4-4. SELECTED PROPERTIES OF THE ORGANIC TEST LIQUIDSa
Water
Dielec- solubi-
Density Viscosity trie lity at Dipole
Solvents at 20°C at 20°C constant at 20°C moment
Organic fluid
Name
Acid, carboxylic Acetic
acid
(glacial)
Base, aromatic
ami ne
Neutral polar,
alcohol
Neutral polar,
ketone
Neutral polar
glycol
Neutral non-po-
lar, alkane
Neutral non-polar,
al kyl -benzene
Water
Anil ine
Methanol
Acetone
Ethyl ene
glycol
Heptane
Xyl ene
• • *
(gm/cfrr) (cent i poise)
1.05 1.28
1.02 4.40
0.79 0.54
0.79 0.33
1.11 21.0
0.68 0.41
•,0.37 0.81
0.98 1.0
at 20 °C (gm/1) (debyes)
6.2 « 1.04
6.9 34.0 1.55
31.2 „ 1.66
21.4 « 2.74
38.7 » 2.28
2.0 0.003 0.0
- 2.4 0.20 0.40
80.4 - 1.83
aFor additional data on these organic liquids, see Table 2-2.
approximately two pore volumes of the standard permeant. In contrast, perme-
ability of calcareous smectite decreased slowly while that of the mixed
cation illite increased slowly; bcth changes were, however-, small.
Relative permeability values for the four clay soils to water are consistent
with values typical for those clay types. Kaolinite exhibited the highest,
noncalcareous (partially sodium saturated) smectite showed the lowest, and
calcareous (calcium saturated) smectite and mixed cation illite had inter-
mediate permeabilities.
After passage of two pore volumes of standard aqueous permeant, the four clay
soils exhibited no visible aggregation and appeared to have retained their
initially massive structure. In addition, the surface of the soils showed no
signs of pore enlargements. - -
Traditionally, permeability tests on prospective clay soil liners for hazar-
dous waste landfills and surface impoundments have used only standard aqueous
128
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solution, such as Q.01N CaS04 or CaC^, as the permeant liquid. All four
of the clay soils shown in Figure 4-1, if only tested with the standard per-
meant, would qualify as adequate for lining hazardous waste disposal facili-
ties on the basis of their low permeabilities of less than 1 x 10"' cm s~^.
gio^
vt —
10'
NONCALCAREOUS SMECTITE A
CALCAREOUS SMECTITE A
MIXED CATION KAOUNITE O
MIXED CATION I LUTE •
WATER (OJ01N CaS04)
OL5 GO Q5 LO I.5
PORE VOLUMES
2.0
2.5
3.0
Figure 4-1. Permeability of the four clay soils to standard
aqueous permeant (0.01N
Organic Acids - Acetic Acid. Organic acids are rarely the predominant liquid
in the leachate generated by a waste. They would usually be present, how-
ever, as one of the dissolved components in whatever liquids leached out
of waste disposed of in an anaerobic environment such as is common in land-
fills and surface impoundments. Effects of dilute solutions of organic acids
on the permeability of clay liners are discussed in subsection 4.2.2.
Permeabilities of' four compacted clay soils to -concentrated (glacial) acetic
acid were measured by Anderson et al (1982) and are presented in Figure 4-2.
Baseline permeability values for the four clay soils were established with
the standard permeant (0.01N CujO,;) and are shown to the left of the dotted
129
-------
line. All four soils showed initial decreases in permeability when the
permeant was changed from the standard to acetic acid.
0.5
NONCALCAREOUS SMECTITE a
CALCAREOUS SMECTITE A
MIXED CATION KAOUNITE O
MIXED CATION ILLJTE •
ACETIC AOD
as
PORE
LO 1.5
VOLUMES
2.0
2.5
3.0
Figure 4-2.
Permeability of the
acetic acid.
four clay soils to glacial
Significant amounts of soil piping occurred in these soils, as indicated by
the soil particles deposited on the bottom of collection bottles. In addi-
tion, effluent from these soils was usually tinted (red, creamy, or black)
indicating that soil components were dissolved by the acid. Initial de-
creases in permeability may be due to partial dissolution and subsequent
migration of soil particles. These migrating particle fragments may have
lodged in the liquid conducting pores, thus decreasing the cross-sectional
area available for liquid flow.
Two of the soils treated with acetic acid (calcareous smectite and mixed
cation kaolinite) decreased continuously in permeability throughout the test
period. After passage of approximately 20% of a pore volume, the acid treated
kaolinitic clay generated a dark red effluent'with the odor of acetic acid.
The color was probably due to dissolution-of iron oxides which comprise about
13% of the solids in the kaolinitic clay soil. The acid-treated calcareous
smectite began passing cream-colored foamy effluent after passage of about
130
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28% of a pore volume. Since the solid fraction of this clay soil is approx-
imately 33% calcium carbonate, the largest portion of the creamy material
probably was dissolved calcium, and the foam the result of C02 liberation
from the dissolved carbonates.
Both noncalcareous smectite and the mixed cation illite eventually increased
in permeability after the initial decreases, but the increases did not
begin until passage of 39% and 62% of a pore volume, respectively. Effluent
from the noncalcareous smectitic clay contained soil particles and. a black
ash, while effluent from the illitic soil contained red-tinted soil particles
that became increasingly darker as more effluent passed. Permeability in-
creases with both of these soils were thought to be due to progressive soil
piping that eventually cleared initially clogged pores.
In light of the across-the-board piping that occurred with the acid treated
clays, any liquid (such as strong acids and bases) capable of dissolving clay
liner components could potentially cause increases in the permeability of the
liner. Anderson et al (1982) suggested that neutralization of acids and bases
prior to their disposal may be the best safeguard against failure of a clay
soil liner.
The density to viscosity ratio of acetic acid (0.82) implies that permeability
should decrease approximately 18% from the value obtained with the standard
permeant. However, the large permeability decreases and subsequent increases
(in two of the soils) indicate that soil piping was the predominant influence
responsible for permeability changes.
Organic Bases - Aniline. Permeabilities and breakthrough curves for four clay
soils permeated by a weak organic base (aniline) were determined by Anderson
et al (1982) and are given in Figure 4-3. Baseline permeability values were
established for the soils with a standard permeant (0.01N CaS04) and are to
the left of the dotted line in Figure 4-3. All four clay soils showed signi-
ficant permeability increases when permeated by the weak organic base.
Both noncalcareous smectite and mixed cation illite had breakthrough of
aniline with concurrent permeability increases at lower pore volume values
(<0.5) than the other two clay soils. The permeability of the noncalcareous
smectite appeared to reach a constant value just above 1 x 10-7 cm sec'l.
Permeability rose above 1 x 10"? cm sec~l and aniline broke through the
kaolinitic soil after passage of one .pore volume. Only the calcareous smec-
tite clay maintained a permeability value below 1 x 10'? cm sec'l. Its
permeability increased rapidly at first, but decreased substantially concur-
rent with aniline breakthrough. After the permeability decrease, this soil
exhibited a slow but steady permeability increase.
There were no signs of migrating soil particles in any effluent samples
collected from the four aniline-treated specimens. Apparently, aniline is too
weak a base to cause significant dissolution of clay soil components. How-
ever, examination of the cores subsequent to the permeability tests indicated
that the organic base caused extensive structural changes in the upper half of
the soils. The massive structure of the four soils after treatment with
131
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the standard permeant was altered by aniline into an aggregated structure
characterized by visible pores and cracks in the surface of the soils. M
NONCALCAREOUS SMECTITE
CALCAREOUS SMECTITE
MIXED CATION KAQUNITE
MIXED CATION I LUTE
0.5
0.0
0.5 LO 1.5
PORE VOLUMES
2.0
2.5
3.0
Figure 4-3.
Permeability and breakthrough curves of the four clay
soils treated with aniline.
According to the equation for intrinsic permeability, a permeant with density
and viscosity of aniline should result in soil permeability 77% lower than
that obtained with water, e.g. the standard permeant. However, the four soils
that were tested underwent increases in permeability between 100% and 200%
when permeated with an-iline. It appears that the predominant factor affect-
ing permeability is the ability of aniline to alter the structural arrange-
ment of particles making up clay soils.
Neutral Polar Organics - Acetone. Many common industrial solvents can be
described as neutral and polar such as ethylene glycol, acetone, and methanol.
Polarity generally indicates that a chemical has a relatively high water
solubility and therefore polar organic liquids -may be present in aqueous
leachates in concentrations ranging from parts per billion to double digit
percentages. In this subsection, data are presented where a polar organic
chemical is the predominant liquid phase Figure 4-4).
132
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NCNCALCARECUS SMECTITE 4
MIXEO CATiCN KAOUNITE O
MIXED CATICN ILUTE •
ACETONE '
CO
0.5 1.0 1.5
PORE VOLUMES
2.0
2.5
3.0
Figure 4-4. Permeability of the four clay soils to acetone.
It is interesting to note that all the clay soils that were permeated with
acetone initially decreased in permeability. These decreases continued until
passage of approximately 0.5 pore volume. During passage of the next 0.5 pore
volume, however, the permeability of the soils underwent large increases.
One possible explanation for this sequence of changes is as follows:
1. The higher dipole moment of acetone caused an initial increase in
the interlayer spacing between adjacent clay particles, as compared
with water, i.e. the standard permeant.
2. As more acetone passed through the soil specimens, more water
layers were removed from clay surfaces. Due to its larger molecular
weight, however, fewer acetone layers were adsorbed than were
adsorbed when water was the only liquid present. This resulted in a
larger effective cross-sectional area available for fluid flow.
While acetone can displace water from clay surfaces, due to its higher dipole
moment, it cannot form as many adsorbed layers as water due to its higher
molecular weight (Anderson, 1981).
133
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Examination of the soil after acetone permeation showed extensive shrinkage
and cracking. Such shrinkage is thought to be associated with dehydration,
indicating that acetone extracts water from soil particle surfaces.
In a study conducted by Green et al (1981), the same initial decrease in
permeability occurred with three other acetone-permeated clay soils. Ap-
parently, however, the tests were not run long enough to pass a sufficient
volume of permeant to observe the large permeability increases that occurred
above 0.5 pore volume in the present study. This further illustrates the
importance of passing at least one full pore volume of a waste leachate to
determine how the liquid will affect the permeability of a clay liner.
Neutral Polar Organics - Methanol „ Permeabilities of four compacted clay
soils permeated by methanol and a breakthrough curve for an illitic clay soil
were determined by Anderson et al (1982) with the standard aqueous permeant
(0.01N CaSO/i) and are to the left, of the dotted line in Figure 4-5. As with
acetone-permeated soil specimens, soil permeated with methanol reached perme-
abilities greater than 1 x 10'7 cm sec"1. Unlike soils treated with acetone,
methanol-treated soils underwent no initial permeability decrease.
Increased methanol in the effluent from the illitic clay soil paralleled an
increase in permeability of the soil. After passage of 1.5 pore volumes, the
hydraulic gradient was reduced from 61.1 to 1.85 and another pore volume of
methanol passed (Figure 4-6). After an initial decrease, permeability
of the soil steadilv increased at the lower hydraulic gradient to a value
greater than 1 x 10~5 cm s"1.
No particles were detected in the effluent from the soil specimen permeated
with methanol; therefore, soil piping was discounted as a mechanism for the
observed increase in eff-luent flow. If these increases were due solely to the
1.46 density to viscosity ratio, permeability of the soils would have leveled
at values 150% of those obtained w th water. Instead, the soils showed steady
permeabi lity% 'increases to values greater than 1,000% (kaolinitic soil) and
10,000% (ill'itic and smectitic soils) of permeability values with the standard
permeant.
Examination of methanol-permeated soil specimens taken from the permeameter
revealed development of large pores and cracks visible on the soil surface
(Anderson et al, 1982). The lower dielectric constant of methanol compared
with water was considered to have caused a decrease in interlayer spacing of
the clay minerals present in the soils,^ thereby promoting the structural
changes. Table 4-2 shows the trend relating dielectric constant to interlayer
spacing for propanol, another low molecular weight alcohol, in various concen-
trations of water. In the case of propanol-permeated clay, both the dielec-
tric constant of the permeant and the interlayer spacing of the clay decreased
as the percentage of propanol in the permeant increased.
Neutral ngnpolar organics. Neutral nonpolar organtc liquids are probably the
largest class of nonaqueous waste liquids. Most'waste oils and a large part
of discarded industrial solvents can be characterized as nonpolar. Common
nonpolar industrial solvents include aromatic compounds, such as xylene and
benzene, and aliphatic compounds, such as heptane. In this subsection, data
134
-------
lOOi
m
IT
UJ
0.
10*
10-
NCNCALCAREOUS SMECTITE A
CALCAREOUS SMECTITE A
MIXED CATION KAOLINITE O
MIXED CATION I LUTE •
_1
METHANOL
2.0
2.5
3.0
ao as 10 1.5
PORE VOLUMES
Figure 4-5. Permeability of the four clay soils to methanol and the
breakthrough curve for the methanol-treated mixed cation
illitic clay soil.
*
are presented where a nonpolar organic chemical is the predominant liquid
pha.se.
Replacement of a polar permeant, such as water, by a nonpolar one was found to
cause permeability increases of between 10% and 30% in compacted kaolinitic
clay beds (Michaels and Lin, 1954). It was concluded that the most important
factor controlling the permeability was the degree of dispersion or disag-
gregation existing in the original permeant.
Xylene--Permeabi1ities and breakthrough curves for four compacted clay
soils permeated by xylene were evaluated by Anderson et al (1982) and are
given in Figure 4-7. Baseline permeability values for the soil specimens
were established with the permeant (0.01N CaSO,;) as shown to the left of
the dotted line in Figure 4-7. Xylene-permeated soils showed rapid increases
in permeability followed by nearly constant permeabilities, roughly two
orders of magnitude greater than their permeabilities to water, i.e. the
standard permeant.
135
-------
Permeability increases due to the ratio of density to viscosity of xylene
(1.07) accounts for only a 7% increase in permeability over values obtained
with water. Since permeability increases averaged 10,000% (two orders of
magnitude), other mechanisms are obviously involved. An indication of these
mechanisms was the structural changes in the xyl ene-permeated soils, illus-
trated by massive structure before permeation and blocky structure after the
soils were permeated with xylene.
Another study by Green et al (1981) noted that neutral nonpolar compounds,
such as xylene, may greatly increase permeability of compacted clay soils by
causing the formation of shrinkage cracks. This study, however, listed the
"equilibrium coefficient of permeability" for the xyl ene-permeated soils as
the low permeability values obtained prior to the formation of the shrinkage
cracks. The authors then plotted these artificially low permeability values
for the neutral nonpolar liquids, vs dielectric constant and arrived at the
following conclusion: All clay soils are more permeable to water than to
organic solvents, which is contrary to the results of the work of Anderson and
Brown.
0.5
0.0
0.5 LO 1.5
PORE VOLUMES
2.0
2.5
3.0
Figure 4-6. Permeability of the mixed cation illitic clay soil
to methanol at two hydraulic-gradients. Permeant
used to the left of the dotted line is 0.01N aque-
ous solution of CaS04.
136
-------
lOO
5U
o
— _
>
H
_)
£
5 I0~=
K Z
UJ _
0.
0
£
2
o
tr
U.
Q
UJ
i
^_ |
NONCALCAREOUS SMECTITE A
CALCAREOUS SMECTITE A
MIXED CATION KAOUNITE 0
MIXED CATION ILLITE •
METHANOL e"'0"
2.0
2.5
3.0
as LO 1.5
PORE VOLUMES
Figure 4-5. Permeability of the four clay soils to methanol and the
breakthrough curve for the methanol-treated mixed cation
i11i t i c c1 ay soil.
*
are presented where a nonpolar organic chemical is the predominant liquid
pha,se.
Replacement of a polar permeant, such as water, by a nonpolar one was found to
cause permeability increases of between 10% and 30% in compacted kaolinitic
clay beds (Michaels and Lin, 1954). It was concluded that the most important
factor controlling the permeability was the degree of dispersion or disag-
gregation existing in the original permeant.
Xylene--Permeabi1ities and breakthrough curves for four compacted clay
soils permeated by xylene were evaluated by Anderson et al (1982) and are
given in Figure 4-7. Baseline permeability values for the soil specimens
were established with the permeant (0.01N CaSC^) as shown to the left of
the dotted line in Figure 4-7. Xylene-permeated soils showed rapid increases
in permeability followed by nearly constant permeabilities, roughly two
orders of magnitude greater than their permeabilities to water, i.e. the
standard permeant.
135
-------
•Permeability increases due to the ratio of density to viscosity of xylene
(1.07) accounts for only a 7% increase in permeability over values obtained
with water. Since permeability increases averaged 10,000% (two orders of
magnitude), other mechanisms are obviously involved. An indication of these
mechanisms was the structural changes in the xylene-permeated soils, illus-
trated by massive structure before permeation and blocky structure after the
soils were permeated with xylene.
Another study by Green et al (1981) noted that neutral nonpolar compounds,
such as xylene, may greatly increase permeability of compacted clay soils by
causing the formation of shrinkage cracks. This study, however, listed the
"equilibrium coefficient of permeability" for the xylene-pemeated soils as
the low permeability values obtained prior to the formation of the shrinkage
cracks. The authors then plotted these artificially low permeability values
for the neutral nonpolar liquids vs dielectric constant and arrived at the
following conclusion: All clay soils are more permeable to water than to
organic solvents, which is contrary to the results of the work of Anderson and
Brown.
10
Q5- CXO
Q5 LO 1.5
PORE VOLUMES
2.0
2.5
Figure 4-6. Permeability of the mixed cation illitic clay soil
to methanol at t*o hydraulic-gradients. Permeant
used to the left of the dotted line is 0.01N aque-
ous solution of CaS04.
136
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100-
NONCALCAREOUS SMECTITE A
CALCAREOUS SMECTITE A
MIXED CATION KAOUNITE 0
MIXED CATION I LUTE •
XYLENE
00
0.5 1.0 1.5
PORE VOLUMES
2.0
2.5
3.0
Figure 4-7.
Permeability and breakthrough curves of the four
clay soils treated witti xylene.
Benzene — Benzene and water were used as permeant liquids to measure the
depth of penetration with time through a compacted clay subsoil (White,
1976). Approximately 90 cm long columns of the clay subsoil were compacted
to 95% of standard proctor density. Test liquids were placed over the
compacted soil and then air pressure was applied to the top of the liquid to
simulate a hydraulic head of approximately 7 meters or a hydraulic gradient
of roughly 24. Table 4-5 gives the depth of penetration with time for water
and benzene when the clay liner was compacted at optimum moisture content
by weight) and for benzene when the clay liner was compacted at 2Q% and
water content by weight.
White (1976) presented no actual permeability values and the report lacked
an adequate characterization of the clay subsoil. However, the following
conclusions can be drawn from that study.
1. When compacted to optimum moisture and 95% of standard proctor
density, the clay subsoil was approximately 100 times more permeable
to benzene than to water.
137
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Table 4-5
DEPTH OF PENETRATION WITH TIME FOR BENZENE AND TAP WATER
PERCOLATING THROUGH A 90 cm COLUMN OF COMPACTED CLAY
Permeant
liquid
Tap water
Benzene
Benzene
Benzene
Compaction
water content,
% by weight
31*
31*
20
10
Elapsed
time,
days
100
36
32
0.63
Depth of
penetration,
cm
2.4
90.0
90.0
90.0
*0ptimum water content.
2. When properly compacted to . a thickness of approximately 90 cm,
the clay subsoil was found to be a suitable liner for a surface
impoundment for tap water, but not for benzene.
3. When compacted at optimum moisture and 95% standard proctor density,
the 90 cm thick clay liner, subjected to a hydraulic gradient of 24
would begin to leak benzene in approximately 36 days.
4. When compacted on the dry side of optimum moisture but still at 95%
standard proctor density, the clay subsoil would be substantially
more permeable to benzene than if the liner had been compacted at
the optimum moisture content.
Heptane -- Penrieabil ities and breakthrough curves for four compacted clay
soils permeated by heptane were measured by Anderson et al (1982) and are
shown in Figure 4-8. Baseline permeability values for the clay soils were
established using the standard aqueous permeant (0.01N CaSO/j) and are shown
to the left of the dotted line in Figure 4-8.
Trends in permeability by heptane were similar to those shown by xylene; that
is, the soils underwent initial permeability increases of roughly 10,000%.
Following these initial large increases, the rate of increase slowed until
nearly constant permeability value;; were observed.
Only the calcareous smectitic clay showed a significant difference in its
permeability to the two neutral nonpolar liquids, with its permeability to
heptane well below its permeability to xylene.
The constant permeability values eventually reached by the neutral nonpolar
treated cores were probably related to the limited ability of these liquids to
penetrate interlayer spaces of the clay minerals. Permeability trends for
neutral nonpolar liquids differed from the continuous permeability increases
observed in clay soils treated with neutral polar liquids such as acetone
(Figure 4-4) and methanol (Figure 4-5).
138
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NCNCALCAREOUS SMECTITE a
CALCAREOUS SMECTITE A
MIXED CATION KAOUNITE 0
MIXED CATION ILL1TE «
HEPTANE
0.5 1.0 1.5
PORE VOLUMES
2.0
2.5
3.0
Figure 4-8. Permeability and breakthrough curves of
the four clay soils treated with heptane.
Reintroduction of Water. As already indicated in this subsection, changes in
the permeability of compacted clay soils permeated by organic liquids do not
follow trends that would be predicted based on changes in viscosity and
density of the liquid. Anderson at al (1982) studied the permeabilities of
clay liners subjected to liquid sequences that might be generated in disposal
facilities. They found that viscosity and density values were useless in
attempting to predict the resulting liner permeabilities.
After the primary leachate (liquids present in a waste) has percolated
through a clay liner, it is followed by a secondary leachate (generated by
water entering the site and percolating through a waste). Anderson et al
(1982) attempted to simulate this leachate sequence by following organic
permeant with the standard aqueous permeant (0.01N CaS04). Figure 4-9
gives the permeability and breakthrough history of a noncalcareous smectitic
clay soil sequentially permeated with standard permeant (0.01N CaS04),
aniline, and then the standard permeant.
139
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100'
-------
TABLE 4-6. PERMEABILITY OF NONCALCAREOUS SMECTITIC CLAY SOIL TO THE FOLLOWING
SEQUENCE: STANDARD PERMEANT-ORGANIC PERMEANT-STANDARD AQUEOUS PERMEANT
Organic
permeant
Aniline
Methanol
Ethyl ene
glycol
Initial permeability
to standard aqueous
permeant
(cm sec"1)
2. 7 to 3.1 x 10"9
1.4 to 1.7 x 10-9
1.2 to 1.5 x 10-9
Permeabil ity to
organic permeant
(cm sec"1)
2.2 x 10"7
1.1 x 10"6
3.1 x 10"7
Final permeability
to standard aque-
ous permeant
(cm sec"1)
2.3 x 10"8
6.0 x 10"8
1.1 x 10"7
4.2.4 Effect of Inorganics on Soil Permeability
Inorganic hazardous industrial wastes can have a considerable impact on the
as-designed soil permeability. Some of the information available on this
subject comes from studies on water quality related to irrigated soils. The
relative proportion of sodium and calcium, and the total concentration of
solutes have a tremendous impact on soil-fluid transmission characteristics
for some particular soils (Gardner, 1945; Lunt, 1963; Quirk and Schofield,
1955).
In the next paragraphs, we summarize some of the results obtained by McNeal
and Coleman (1968) who tested seven soils from western USA. The results
indicated that, in general, the replacement of an originally present, high-
solute concentration solution by a less concentrated one, results in a soil
with a lower permeability. The reduction in permeability is proportional to
the SAR value of the solution, i.e. the higher the SAR, the more drastic the
drop in the K value of the soil. For solutions with SAR = , a flux corre-
sponding to 20-40 pore volumes is sufficient to reduce the permeability to
half of its original value.
Some soils were less vulnerable to this effect compared to others. Thus, the
Aiken soil with 60% of the clay fraction made up of kaolinite was quite
insensitive to liquid chemical composition and the drop in K value was never
larger than 25% of the original value.
The Gila soil (New Mexico), on the other hand, with more than 60% clay, 48%
of which is made up of montmoril lonite, displayed the regular drop in permea-
bility with a decrease in salt concentration at a low SAR and - unlike all
other soils containing moderate amounts of montmoril lonite - displayed a
reversal of this effect upon an increase in salt concentration. The impli-
cation of this fact is that, if a liner is constructed using a soil material
similar in characteristics to Gila soil, an increase in permeability is to be
expected if the replacing solution ..(waste effluent) is more concentrated'than
the replaced solution. Oddly enough, this undesirable behavior is expected in
a predominantly montmoril lonitic clay soil, the type of material highly recom-
mended for use as a soil liner. This observation is not intended to negate
141
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the merits of high clay content montmorillorn'tic soils. Indeed, the general
consensus seems to be that soils with permeabilities below 10~° cm sec" can
be constructed using only montmori1lonitic clay soils. However, the McNeal
and Coleman (1966) results draw attention to the sensitivity of this type of
soil and, thus, to the possibility that during service, a properly designed
and constructed soil liner can increase its permeability to untolerable
levels.
4.3 EFFECTS OF WASTE LIQUIDS ON FLEXIBLE POLYMERIC MEMBRANES
4.3.1 Introduction
Available information obtained from the field on the effects of waste liquids
on flexible membrane liners is limited. Consequently, most of this discussion
of the effects upon these liner materials of exposure to various waste liquids
will be based upon laboratory and simulated exposures. The principal experi-
ence in the field with membrane liner materials has been with water impound-
ment and conveyance. There also has been some experience with the impoundment
of brines. The experience with waste liquids, however, is relatively recent,
although membrane-lined impoundments for waste water have been used since the
1960's. Some .nformation regarding field performance with MSW leachate is
reported for a few membrane liners.
Use of polymeric membrane liners for water conservation and conveyance was
started in the 1940's and the first membranes were used for lining canals in-
1948. These liners were butyl-ccated fiberglass. Later, a number of water
reservoirs, catchment basins, cana'!s, and ponds were lined with butyl sheeting
(Dedrick, 1980; Smith, 1980; Lauritzen, 1967). A variety of other polymeric
membrane liners were also developed based upon such polymers as polyvinyl
chloride (PVC), polyethylene (PE), chlorosulfonated polyethylene (CSPE or
CSM), and chlorinated polyethylene (CPE). These -vere all- used in the con-
servation, collection, storage, anc conveyance of water.
Use of polymeric membrane liners for lining waste disposal sites began in the
early 1970's principally because their low permeability appeared to be
effective for preventing the migration of toxic constituents from waste
sites. At that time, little was known as to the effects wastes would have on
polymeric membranes and how long the service lives of liners might be.
Because of the potential impact that pollutants from waste disposal site's
might have on the groundwater quality, EPA initiated research work in this
area to determine the state-of-the-art with respect to liners and to assess
the various liners available under conditions which simulated as closely as
possible actual service conditions. EPA felt that the test results from this
type of evaluation would give the greatest credibility to the use of lining
materials for land waste disposal facilities.
Two EPA projects were undertaken to assess the effects of various wastes
upon a wide spectrum of potential liner materials which have been used in the
142
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handling of water. The first project dealt with the exposure of lining
materials to sanitary landfill leachate and the second with similar types of
liners exposed to hazardous wastes. These liner materials included flexible
polymeric membranes, soils, spray-on membranes and various admixed materials.
Particular emphasis was placed on the first type because of the low perme-
ability of these materials and their growing use. The membrane materials
selected for these studies were those that were commercially available in
1973-1975 and were tested, if available, at a single thickness of 30-40 mils.
In this section, the methodology used in these studies is briefly described
and the available results of the exposures of the polymeric membranes are
summarized. The results on other lining materials, i.e. admixes, soils, and
spray-on materials, are presented in other sections of this- chapter.
The first project, concerned with liners for MSW landfills, has been completed
and ne final report prepared (Haxo et al, 1982). The second project, con-
cerned with liners for hazardous waste disposal facilities, is to be completed
by the end of 1982.
4.3.2 Exposure of Membrane Liners to MSW Leachate
The work summarized in this section was primarily an exploratory study
concerned with the interaction of liner materials with a representative MSW
leachate over an extended period of time. Except for a study of seaming, the
project did not discuss the design of landfills or the installation of liners,
both of which are very important factors in the successful construction and
functioning of disposal facilities. All membrane materials'were commercial
products that had been requested from the 'liner industry as being suitable for
the lining of sanitary landfills. It was recognized at the outset of the
study that the liner compositions selected and submitted by the industry had
not necessarily been used in the lining of MSW landfills. However, they
represented the state-of-the-art at that time and were all considered poten-
tially effective as linings for MSW landfills.
4.3.2.1 Experimental details
To evaluate membrane liners exposed to landfill leachate, liner specimens,
two feet in diameter, were placed under eight feet of ground refuse in land-
fill simulators (Figure^ 4-10). An individual simulator consisted of a two-
foot diameter steel pipe, ten feet in height, placed on an epoxy-coated
concrete base (Figure 4-11). The six polymeric membranes that were exposed as
primary liners in the simulators were:
- Butyl rubber.
- Chlorinated polyethylene (CPE).
- Chlorosulfonated polyethylene (CSPE).
- Ethylene propylene rubber (EPDM).
- Polyvinyl chloride (PVC).
The liner specimen was sealed in the base w-ith epoxy so that it could not be
bypassed by the leachate. Each liner 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 one
143
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GAUGE
SHREDDED REFUSE
MASTIC SEAL
CONCRETE BASE
SAND
SEALING RING
%" DRAIN ROCK 3" THICK
SOIL COVER
1% FT. THICK
POLYETHYLENE
SPIRAL-WELD PIPE
2 FT. DIA. x 10 FT. HIGH
GRAVEL
LINER SPECIMEN
DRAIN ABOVE LINER
DRAIN BELOW LINER
Figure 4-10. Landfill simulator used to evaluate liner materials exposed
to sanitary landfill leachate.
cubic yard o.f ground refuse was compacted above each liner in approximately
four-inch lifts to yield a density of 1240 pounds per cubic yard at a 30
percent water content. The refuse was covered with two feet of soil and four
inches of crushed rock.
Tap water was introduced at the rate of 25 inches per year. Leachate generat-
ed in each cell was ponded above the specimen at a one-foot head by continu-
ally draining into a collection bag. Any leachate which seeped through the
liner was collected below the liner.
In addition to the primary liner specimens, 2.5 x 22 inch specimens were
buried in the sand above the liner and were thus totally immersed in the
leachate. Two sets of each material were exposed- in the simulators. One set
of simulators was dismantled at the end of one year and the second set at the
end of five years. Additional immersion testing was performed outside the
simulators by passing leachate through cells in which 8 x 10 inch specimens of
144
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SI
s r j- < (/,
< i s
s
-PE
f
-r <-— y r
' r^V ^ J
5
^ ^
S REFUSE
> ' * * s r
^ r ^ x -N.
•'.•'.V'.-:.::-.r;:-.-SAND-'. ;-..-;•,;
EPOXY SEAL : .
MEMBRANE LINER
•\
•%
r ^
\\
1 FT
BAG
Figure 4-11. Base of the landfill simulator in which the liner materials were
exposed. The refuse at the bottom of the column was anaerobic.
The leachate was maintained at a head of one foot by U-tubes.
Plastic bags were sealed at both outlets. Strip specimens of
membrane liners were buried in the sand for exposure to leachate.
the membrane liners were hung. The specimens that were removed from the
simulators and from the immersion cells were subjected to a range of physical
tests normally performed on rubber and plastic materials. These tests are
listed in Table 4-7.
TABLE 4-7. TESTING OF POLYMERIC MEMBRANE LINERS
Before and After Exposure to Wastes
Thickness
Tensile strength and elongation at break, ASTM D412
' Hardness, ASTM D2240
Tear strength, ASTM D624, Die C
Water absorption or extraction at RT and 70°C, ASTM D570
Seam strength, in peel and in shear
Puncture resistance, Federal Test Method Standard
No. 101B, Method 2065
Water vapor transmission, ASTM. £96,.. ,..
Specific gravity and ash
Volatiles and extractables
145
-------
4.3.3 Laboratory Results of Exposure to MSW Leachate
The primary liners were recovered from the simulators after 12 and 56 months
of exposure. None of the membrane liners that had been well sealed into the
bases of the simulators showed any seepage. The epoxy seals in 3 of the bases
containing membrane liners failed during the last year of operation of the
simulators. The absence of seepage confirms the very low permeability of the
membrane lining materials. The results also show the adequacy of the seams
that were placed in the liners.
Exposed liner specimens were cut from the bases while they were still wet
and sealed in polyethylene 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 were dried prior to testing. In all of the bases
from which the specimens were cut, the square-woven glass fabric and gravel
below the liners were in an "a:; new" condition, except in the base that
contained the CSPE liner, 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 analyses anc physical testing of the specimens before
and after exposure are presented in Table 4-8. These test results are divided
into analyses, physical properties, and seam strength, and are arranged by
liner material and by exposure time. All tests on exposed samples were made
as soon as possible after removal from service. This procedure results in the
determination of properties of the liners as they existed in the' actual
service envi ronment.
To estimate the amount of leachate absorbed by a 1iner.material , the volatiles
content of a sample of the exposed material was measured. The absorption of
leachate by a liner can be calculated when the original weight of the specimen
is known such as is known when laboratory tests are made. In the field,
however, it is necessary to cut a sample from the exposed liner and determine
its volatiles content. In such cases, the absorption of leachate also re-
quires information as to the extractables that are lost and the non-volatiles
that are absorbed. Most leachates are essentially volatile, except for minor
amounts of inorganic dissolved salts. The CSPE, CPE, and EPDM liners, in this
order, had the highest volatile contents; therefore, they absorbed the greater
amounts of leachate. The LOPE, PVC, and butyl liners had the lowest volatile
contents and absorbed lesser amounts of leachate.
By comparing the amounts of extractable material in exposed specimens that
have been dried, the amount of plasticizer or other ingredients in the
compound that was lost to the leachate can be calculated. In all cases, the
extractables, after 56 months, were lower than the original extractables.
The magnitude of the loss, even in the case of the EPDM and PVC, was in the
order of 10%.
The tensile properties of the materials 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
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trends toward increasing values. Tests which reflect the stiffness of the
materials, such as modulus, stress at 200% elongation, and hardness, showed a
minimum at 12 months. These minima may reflect the changes in the composition
of the leachate; 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 sheetings showed good retention of properties during exposure,
there was a significant drop in several cases in the seam strength of the
materials. This showed up in the CPE, CSPE, and EPDM specimens, though this
loss of adhesion did not result in any seepage or leakage of the liner speci-
mens. The fact that there was no leakage may have been due to the lack of
stress on the specimens. The simulators were designed not to allow any stress
on the specimens because of doubts that stress could be controlled.
Overall, the changes in the physical properties of the membranes result-
ing from 56 months of exposure were relatively minor. All of the membranes
softened to varying degrees during the first 12 months. This change is
probably due to the swelling by the leachate. In the interval of time to 56
months, the PVC, CSPE, and CPE membranes rehardened slightly, possibly indi-
cating, in the case of the PVC membrane, loss of plasticizer and, in the case
of the CSPE and CPE membranes, crosslinking of the polymers. They all re-
covered most of their tensile properties that were lost due to the initial
softening. These materials were all thermoplastic and unvulcanized.
Of the six polymeric membranes, the LOPE film best maintained original
properties during the exposure period as shown in Table 4-8; it also absorbed
the least amount of leachate. However, this membrane, which was 10 mils in
thickness, probably has too low a puncture resistance for use in lining a
landfill. This deficiency was confirmed in handling it in the lining of the
steel pipes of the simulators, in the preparation of the primary liner
specimens, and in the making and use of the LDPE leachate collection bags.
The butyl and EPDM liners changed slightly more in physical properties
than did the LDPE liner during the exposure period.
The fact that, except in the bases in which the epoxy resin sealing ring
deteriorated, no leachate appeared below the membrane liners during the
exposure period indicates that the very low permeability of the polymeric
membranes is maintained after extended exposure to MSW leachate.
A comparison of the swelling of membrane materials in water and in leachate is
presented in Table 4-9. The composition of the leachate at the end of the
first year of operation of the simulator is presented in Table 4-10. The data
for most of the membrane liners show that the swelling in leachate is signifi-
cantly higher than that in water in spite of the dissolved inorganic constit-
uents in the leachate. This greater swelling is probably due to the organic
constituents in the leachate. The neoprene and CPE membranes swelled less in
leachate than in water. - -
149
-------
TABLE 4-9. WATER AND.LEACHATE ABSORPTION BY POLYMERIC LINERS*
(Data in percent absorbed by weight)
Butyl rubber
Chlorinated polyethylene (CPE)
Chlorosul fonated polyethylene
Ethyl ene propylene rubber (EPDM)
Neoprene
Polybutylene
Polyethylene
Polypropylene
Polyvinyl chloride
Liner
no.
7b
22
24
12b
13C
23
3
4c
6&> c
14C
8
16b
18
25
26
9
20
21b
27
10
11
15
17b
19
Water-RT
1 year
1.60
1.70
1.10
13.10
19.60
15.i50
17.40
18.00
9.20
11.20
1.40
4.80
• • •
1.50
1.60
22.7
0.25
0.20
0.28
1.85
1.85
2.10
1.85
0.60
Leachate
1 year
1.78
2.32
1.0
9.0
12.4
10.3
20.0
19.0
13.64
8.71
5.95
5.50
• • •
5.99
8.99
8.73
0.33
0.25
0.40
6.72
5.0
4.64
3.29
0.75
(1977).
^Liners mounted in generator bases.
cFabric-supported liner.
150
-------
TABLE 4-10. ANALYSIS OF LEACHATE3
TestValue
Total solids, % 3.31
Volatile solids, % 1.95
Nonvolatile solids, % 1.36
Chemical oxygen demand (COD), g/L 45.9
pH 5.05
Total volatile acids (TVA), g/L 24.33
Organic acids, g/L
Acetic 11.25
Propionic 2.87
Isobutyric 0.81
Butyric 6.93
Source: Haxo, et al (1979).
aAt the end of the first year of operation when
the first set of liner specimens were recovered.
In Table 4-11 the absorption of the primary and buried liner specimens after
twelve months of exposure to leachate is compared with samples of similar
materials immersed in leachate for 8 and 19 months. The data show that the
buried specimens which are exposed on both sides to the leachate tend to swell
slightly more than the primary specimens which are exposed to the leachate on
only one side. The swelling of the specimens, that were immersed completely
in leachate which flowed by the specimens as they were hung in the immersion
cells, was equal to or greater than the swell of the buried specimens.
Leachate flowed by the latter specimens but at a slower rate.
Overall, these results indicate that the leachate tends to swell the membranes
more than does water and that exposure from two sides yields somewhat higher
swelling values. In some cases, there was a levelling off with time of the
degree of swelling by the leachate. However, the composition of the leachate
was simultaneously changing, with the levels of the organic constituents
dropping with time.
Significant variations in properties and effects of the exposure can be
observed among the membranes of a given generic type, as shown in Figures 4-12
and 4-13 regarding absorption of leachate—and tensile strength retention,
respectively. In Figure 4-12 the specific membranes are numbered on the bars.
151
-------
TABLE 4-11. SWELLING2 OF POLYMERIC MEMBRANES ON EXPOSURE TO MSW LEACHATE
Exposed in simulators, months Immersion in flowing
Primary Buried leachate, months
12 56 12 56 8 19 30.5
Butyl rubber
Chlorinated polyethy-
lene
2.0
6.8
2.4
7.61
1.8
9.0
2.0
10.1
1.4
7.9
2.6
14.4
1.96
9.95
Chlorosulfonated poly-
ethylene
Ethyl ene propylene
rubber
Polybutylene
Polyethyl ene
Polyvinyl chloride
* • •
12.8
5.54
...
0.02
3.6
13.' 90
5.74
* * •
1.95
2.* 08
20.0
13.6
6.0
0.3
0.3
5.0
3.3
0.8
14.7
17.0
6.5
0.2
2-0
1.30b
0.5
18.6
12.1
2.9
-0.2
0
2.4
2.3
0.9
22.8
14.9
3.8
0.7
0.2
4.4
4.4
1.9
17.24
14.53
5.98
0.46
0.10
3.87
3.02
1.45
aMeasured by percent volatiles of the exposed material.
bForty-three months in simulator.
The length of the bars show the range of absorption values obtained for a
liner material of a given polymer type. For example, one neoprene liner at 8
months swelled approximately 2% and another approximately 20%; at 19 months
the spread had become 3% and 32%, respectively. The effects of 8, 19, and 31
months of immersion in leachate upon the S-200 modulus of the membranes are
shown in Table 4-12 and upon tensile strength are shown in Figure 4-14.
Table 4-13 presents, the variations; observed with different PVC membrane speci-
mens that had been buried in the sand above the liners in the simulators.
4.3.4 Field Verification of Membrane Liner Performance
Though considerable information has been and is being developed in laboratory
and pilot studies, information regarding the performance of lining materials
in extended service in MSW landfills with exposure to leachate has been very
limited. First, the lining of landfills, particularly with flexible polymeric
membranes, is relatively new, i.e. from the early 1970's. Second, effective
and economic methods have not been developed for sampling and repairing the
holes cut in the linings of-landfills.- - —.
152
-------
KIV
3 I MOHTHI IMMCMrON
• T| MONTWI !MMf NIlQN
• T* .IMl* NO
Figure 4-12 Ranges of swelling values of membranes of different polymeric
types during immersion in leachate for 8 and 19 months. The
number of different liners of a given polymer that are included
in the test is shown in parentheses.
BUTYL RUBBER
CHLORINATED
POLYETHYLENE
CHLOCOSUUFONATED
POLYETHYLENE
ELAST1CI2ED
POLYOLEFIN
RUBBER
NEOPRENE
POLYBUTYLENE
POLYETHYLENE
POL YVINYL CHLORIDE
Gl
KEY
t MONTHS IMMERSION
19 MONTHS IMMERSION
50
TSNSltE STRENGTH.
100
'GlNAL
ISO
Figure 4-13 Ranges of retentions of tensile -strength of membranes of dif-
ferent polymeric types on immersion in landfill leachate for 8
and 19 months. Tensile strength data were obtained by averaging
the tests in machine and transverse directions.
153
-------
TABLE 4'
R£TENTION OF
Polymer
Butyl rubber
Chlorinated polyethylene
Chlorosul fonated polyethylene
Elasticized polyolefin
Ethyl ene propylene rubber
Neoprene
P-olybutyl ene
Polyester elastomer
Polyethylene
Polyvinyl chloride
Polyvinyl chloride + pitch0
:'
Modulus S-200 of
unexposed membrane,
psi
— — '••
685
1330
1205
810
35
1525b
1770
1020
655
755
1040
920b
855
1235
1635
1340
3120
2735
1260
2125
1965
1740
1720
1705
2400
2455
1020
=====
= • ==
Retent
of ori
8 mo.
"™ ' " • «,
86
85
89
98
54
116b
77
99
134
111
100
98b
91
79
100
93
101
102 •
106
87
80
89
91
92
79
96
85
— -
"
_
i—
ion on e
ginal vc
19 mo.
90
89
90
106
46
136b
108
103
131
109
99
98b
92
77
100
101
101
98
102
85
84
94
91
105
88
95
86
— i
1
' -
exposure
ilue, %
31 mo.
""' -.
98
95
104
133
57
• • •
130
107
134
117
105
104b
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 trans-
verse di rections.
bMembrane is fabric reinforced.
CS-100 values given; ariginal and subsequent exposed specimens failed at less
than 200% elongation.
154
-------
100 C
:SI>E
•JO 35
p r, . JJOO >SI
h
r- ,
"10 33 faafl'C ^
I r
X I
- r
,r
200 400 MO dOO '000
OAVS CXPOSCD
200 '00 SOO 300 <000 0 200 400 sOO 300 000 0 200 100 JOO 300 '000
OAVS EXPOSED OAYS EXPOSED DAYS EXPOSED
Figure 4-14 Retention of tensile strength of the individual polymeric mem-
branes as a function of immersion time in landfill leachate.
Tensile strength values based, up.on the average data obtained in
the machine and transverse directions. Liner numbers and initial
tensile strength for each liner are shown. Data are given for 8,
19, and 31 months.
155
-------
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Several lined disposal sites which were being closed became available for
sampling of the liners that had been used. These sites were either small
cells made in demonstration projects or full-scale sites that were being
closed because of their inadequate size. These sites were:
- A demonstration MSW cell in Crawford County, Ohio, which had been in
service for six years.
- A sludge lagoon in the northeastern United States.
- The Boone County, Kentucky, field site of the EPA, which had been
operating for more than nine years.
- Two experimental cells which had been in operation for four years
at Georgia Institute of Technology.
Samples of the liners were taken from each of these sites and submitted
to laboratory tests to assess the physical properties and compositions of the
exposed samples. However, no unexposed samples were retained for reference
purposes to determine the retention in properties. Observations on the
liners from each of the sites are discussed below.
4.3.4.1 PVC liner in small demonstration landfill
The Crawford County, Ohio demonstration landfill was placed in the spring
of 1971 and lined with a 30 mi 1 PVC sheeting. It had been designed to compare
conventionally-processed solid waste with a shredded waste, and with a rough
compacted waste. The three types of refuse were placed in cells lined with
the PVC membranes that were essentially large waterproof bags.
The effect of water content on consolidation and decomposition of the refuse
was to be determined but the cells were f-looded 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. A layer of clay had been placed on the PVC liner and when the cells
were opened and the clay tested, it was found to have a low permeability.
Thus, it appears that none of the leachate in the cell had contacted the
liner.
The testing results of both the liner that was at the top of the cell under
two feet of clay and the liner that was at the bottom of the cell are reported
in Table 4-14. The liner beneath the refuse had swollen somewhat and soft-
ened. There was also an indication that the liner at the top had lost
some plasticizer. The sheeting itself had sustained considerable distortion
during its exposure due to rough ground or to the gravel on which it was
placed. In spite of the lack of a retained sample for comparison, it appears,
judging by the test values of the exposed sheeting, that the overall proper-
ties, including the seam strength, probably changed little during the ex-
posure.
157
-------
TABLE 4-14. PROPERTIES OF 30 MIL POLYVINYL CHLORIDE LINER
RECOVERED FROM A DEMONSTRATION LANDFILL IN CRAWFORD COUNTY, OHIO
Liner number
Exposure
Analytical properties:
Volatiles, (2 h at 105°C), %
Specific: gravity (dry basis)
Ash (dry basis), ASTM D297, %
Extractables, (dry basis)
ASTM D3421, %
Physical properties:
Thickness, mi 1
Tensile strength, psi
Elongation at break , %
S-100, psi
S-200, psi
Tear strength, ppi'
Hardness, Durometer points
Puncture resistance, Ib
Elongation, in
Seam strength in shear, ppi
Locus of failure3
aSE = Break at seam; BRK - break
96
Top of fill
0.41
1.260
6.14
34.10
30
2630
350
1270
1790
372
70A
41.4
0.66
49.5
SE
in tab.
97A
Bottom of fill
1.33
1.265
6.01
34.43
28
2515
340
1135
1695
342
72A
37.3
0.65
45.5
SE-BK
4.3.4.2 PVC liner in sludge lagoon
A disposal facility containing
-------
changes. Also, it is not certain whether any of the sheeting had been exposed
to anaerobic conditions.
The samples taken from the under the soil or sludge ranged in volatiles
content from approximately 1% to more than 8%. They also ranged in extract-
ables from 29 to 36.7%, indicating that PVC sheeting, even under a cover, can
lose plasticizer.
The sheeting that had been exposed to the weather was taken from the berm
and had become so brittle that it fragmented on touch. Analytical and physi-
cal test data of samples of three of the recovered sheetings are presented in
Table 4-15. It is quite apparent from these data that a PVC liner must be
covered and probably should be thicker than 15 mils.
4.3.4.3 Boone County field site
The closure (Emcon, 1981) of the Boone County Field Site provided an oppor-
tunity to recover CSPE, CPE, and LDPE lining materials that had been under
exposure to conditions of an MSW landfill environment for more .than nine
years. This site had been operated by the Solid and Hazardous Waste Research
Division of the EPA from 1971 through 1980 (Wigh and Brunner, 1981).
Four samples of sheetings, three chl orosulfonated polyethylene (CSPE) and one
low-density polyethylene (LDPE) were taken from Test Cell 1 and six samples of
the chlorinated polyethylene (CPE) liner were taken from Test Cell 2-0; four
of the latter were taken from the bottom of the cell and two that had been
exposed to weather from above ground. All three liner materials were unsup-
ported, and all samples, except the two that were above ground, were 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 data on representative samples are presented in Table 4-16,
which includes data on LDPE, CSPE, CPE taken from the bottom of the cell and
CPE taken from above the ground. Test results on all of the CSPE samples were
very similar and are averaged in the table.
During the operation of the cell, an attenuated leachate contacted the
CSPE sheeting. The quantity that permeated through the soil and was collected
was a fraction of one percent of the amount generated in the cell. The
quality of this leachate was more dilute than the leachate that was collected
above the clay. In other words, these CSPE samples were in contact with a
dilute leachate for approximately nine years.
The CSPE liner samples showed a substantial absorption of the dilute leachate,
ranging in swelling 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.
The LDPE film was clear after the surface stain was removed by washing.
and appeared to be unaffected by the exposure to the MSW leachate during the
nine years of exposure. The sample which was in direct contact with the
full-strength leachate showed little swelling and its properties appeared to
be normal for a LDPE of 6-7 mils thickness.
159
-------
TABLE 4-15. ,-ROPERTIES OF 15 MIL POLYVINYL CHLORIDE LINER MEMBRANE
EXPOSED AT A SLUDGE LAGOON IN THE NORTHEAST FOR 6.5 YEARS
Covered by soil or sludge
Analytical properties:
Volatiles, %
Ash (dbV, %
Specific gravity (db)
Extractables (db)*, %
Physical properties^:
Thickness, mil
Tensile at break, ppi
Elongation at break, *
S-100, ppi
S-200, ppi
Tear strength, 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 tetrachl oride and methyl
alcohol.
^Tensile and tear values are averages of machine and transverse directions.
The samples of CPE lining material taken from the bottom of the cell had
been in direct contact with the leachate generated in Cell 2-D and were stiff
and leathery. They showed a significant absorption of the leachate, ranging
in volatiles content from 16.7 to 18.83.
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.
The data on the volatiles and the data on the devolatil ized samples indicate
that two different compositions were involved. The A and C samples are one
composition and the B sample another composition. The two B samples have
somewhat less ash content, lower volati.les, and, lo.wer extractables. Differen-
ces also occur in the results of the physical property tests.
160
-------
TABLE 4-16. EFFECTS ON CHLOROSULFONATED POLYETHYLENE, LOW-DENSITY
POLYETHYLENE AND CHLORINATED POLYETHYLENE SHEETINGS OF
EXPOSURE IN MSW CELLS AT BOONE COUNTY FIELD SITE FOR 9
YEARS
Property
Analytical properties:
Volatilesd, %
Ash (db)e, %
Speci fie gravity (db)
Extractables (db), %
Physical properties:
Thickness, as received
mi 1
Thickness, after
drying, mil
Tensile at yiel d,
ppi
Breaking factor,
ppi
Elongation at break, %
S-100, ppi
S-200, ppi
Tear strength, 1 b
Hardness, Durometer
points
In
CSPEa*b
Below clay
layer
26.5
22.4
1.446
3.27
43.8
45. 7f
• • «
52.6
325
19.2
32.4
6.5
57A
Cell 1
LDPEC
In contact
with cement
• • •
0.15
• • •
1.10
7.0
6.6?
9.9
10.6
285
9.6
9.65
2.9
• * •
In Cell
CPEa
Under
waste
18.8
13.36
1.372
4.81
41.5
39.2
• « •
49.. 8
280
26.9
39.8 .
7.3
67A
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
Puncture strength
Stress, Ib
Elongation, in.
34.2
0.89
7.0
0.37
36.6
0.78
46.4
0.68
^Nominal thickness of sheeting = 30 mils.
Averages of the results on three samples of the CSPE liner; all three were
taken from below the clay layer and had been in contact with ful1-strength
leachate.
^Nominal thickness of sheeting = 6 mils.
dVolatiles equals the accumulated weight loss on drying for seven days in air
at room temperature, six days in oven at 50°C, and two hours in air oven at
105°C.
®Dry basis. . . . ..
•'Specimens shrank and became thicker.
161
-------
In spite of the significant swell of the CPE sample that had been exposed
to the full-strength leachate, the properties of the swollen CPE were reason-
ably good.
Compared with the samples that, had been exposed to the leachate in the
cell, the weathered materials are significantly higher in tensile strength,
moduli, and puncture resistance (Table 4-16). The lower values for the leach-
ate-exposed CPE probably reflect the swelling by leachate; however, crosslink-
ing during exposure may contribute to the higher values of the weathered
samples.
4.3.4.4 CSPE membrane liner without fabric reinforcement
The pilot scale landfill cells at Georgia Institute of Technology were
constructed and put into operation as part of a research investigation to
study the effect of leachate recycling upon the consolidation and stabiliza-
tion of municipal solid waste. The cells consisted of two adjoining struc-
tures, each with a 10 x 10 ft base and 17 ft in height. They were built
of concrete and fully lined with an unsupported CSPE membrane. One cell was
left open at the top and the other sealed. Two drain systems were incor-
porated in the bottom of each, cell, one in the gravel layer above the liner
and one in the gravel layer between the liner and the concrete base. Shredded
MSW was added to the cells and compacted to a density of 540 Ib yd"^. The
open cell had 9 ft of waste and the closed cell 8.5 ft of compacted waste. In
both cases another layer of gravel with the leachate distribution system was
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.
At the conclusion of the study after four years of operation, the cells
were emptied and the liners recovered. Because the liners in the two cells
were exposed to a variety of conditions within the cells, the effects of this
variation in location of a liner within a site on liner performance could be
measured. The liner in the cell that was open at the top encountered normal
weather conditions and sunlight, as well as differences in exposures between
the waste and the soil cover. The liner 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 4-17. In parti-
cular, 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 the south and the sheeting on the south wall
facing north. The sheeting on the north wall yielded the maximum increase in
modulus and in cure. The sheeting that was below the waste appeared to lose
in ash, perhaps due to solubilization by the leachate.
4.3.5 Exposure of Membrane Liners to Hazardous Wastes
The second study was concerned with the laboratory evaluation of a wide
range of liner materials, including membranes, on exposure to a variety
of hazardous wastes. Our basic approach was to expose specimens of the
various commercial lining materials under conditions which simulated real
162 '
-------
TABLE 4-17. EXPOSURE OF CSPE LINER WITHOUT FABRIC REINFORCEMENT IN PILOT-
SCALE MSW LANDFILL CELLS AT GEORGIA INSTITUTE OF TECHNOLOGY3
Cell
Compass orientation
Level in cell
Thickness, mil
Analytical properties:
Volatiles, %
Extractables (db), %
Ash (db), %
Physical propertiesb:
Tensile at break , psi
Elongation at break,
Set after break, %
S-100, psi
S-200, psi
Tear resistance, ppi
Puncture resistance:
Thickness, mi 1
Stress, Ib
Elongation, in
Hardness, Durometer
points
N
Above
soil
29.1
3.62
• * •
41.9
2380
% 360
95
655
930
200
30.7
36.8
0.88
76A
Open
SE
Above
soil
29.1
9.01
1.50
39.9
2190
350
72
610
740
140
22.0
27.9
0.51
78A
Cell
N
In
soil
31.9
13.8
• « •
40.3
1740
545
227
405
510
187
34.5
33.4
1.33
64A
SW
Below
waste
52.8
23.7
• * •
36.6
1335
485
170
320
420
151
40.3
41.6
1.61
56A
Cl
SW
Above
soil
33.1
2.3
2.00
40.6
1770
570
206
420
510
213
32.7
27.3
1.12
75A
osed eel
N
In
soil
34.3
19.0
• • •
40.7
1450
545
206
280
375
159
36.4
33.9
1.72
60A
1
E
Below
waste
39.0
26.5
• * •
37.8
1450
485
154
335
450
138
41.2
39.0
1.71
51A
Seam strength:
Shear
Peel ,
, Ppi
average, ppi
33.
17.
4
4
35.
14.
5
2
30
12
.0
.4
40.
14.
5
2
34.3
15.8
22.2
13.8
aPohland et al (1979).
^Tensile and tear values are averages of machine and transverse directions.
cValue reported is the maximum stress. Seam failed after initial maximum.
service, using actual wastes, to measure seepage through the specimens, and to
measure effects of exposure by following changes in important physical proper-
ties of the respective lining materials.
In this study, various membrane lining materials were subjected to seven types
of exposure testing:
- Bench screening tests; small specimens iimnersed in wastes.
- Primary exposure cells; one-side exposure to waste.
- Weather test; roof exposure.
163
-------
- Weather test; small tubs lined with membranes arid containing
wastes.
- Water absorption at room temperature and 70°C.
- Membrane bags containing wastes in deionized water; one-side
exposure.
The above exposure conditions are discussed and tests presented:
1. Primary exposure tests.
2. Immersion tests of membranes.
3. Pouch test of membranes.
4.3.5,1 Exposure of primary liner specimens
In this part of the study, specimens of one square foot of eight different
polymeric membrane liners were exposed below one foot of waste in cells which
simulated ponds. The wastes included two strong acid wastes, a strong alkali
waste, an oil refinery tank bottom waste, a lead waste from gasoline, saturat-
ed and unsaturated hydrocarbon wastes, and a pesticide waste. Characteristics
of these wastes are presented in Tables 4-18 and 4-19.
The exposure cell for the primary specimens is shown schematically in Figure
4-15. A similar type of exposure cell has been used for the thick admix and
soil liners (Figure 4-16). Each membrane specimen was prepared with a field-
type seam across the center made according to the recommended practice of the
supplier of the membrane. Two specimens of each liner material were placed in
two sets of cells which were loaded with portions of the same waste. The
cells were dismantled at two exposure times and the liner specimens were
recovered, analyzed, and their physical properties measured.
The first set of primary specimen;; was removed after one year of exposure and
the second set after approximately 3.5 years of exposure to the wastes.
Selected data on the second, set after 3.5 years of exposure are presented in
Tables 4-20 and 4-21. Table 4-20.presents the results of tests for volatiles
and extractables of the eight membrane liners exposed in four different
wastes. The volatiles were determined on a sample of the liner immediately
after removal from the waste and the extractables were determined on the
specimen which had been devolati1ized. Results show the variation in the
volatiles and extractables both with respect to the polymer type and the
waste. There are indications tha", in some cases, the plasticizer which was
in the original compound was removed during the exposure period. In other
cases, the extractables were higher, indicating the absorption of nonvolatile
constituents in the waste.
Table 4-21 presents the effects of one and three years of exposure upon
ultimate elongation and S-100 modulus of the same liner materials in the same
wastes. ' ' "".
The effects of 3.5 years of exposure to the wastes varies considerably with
the liner material and the waste. Only one material, a polyester elastomer,
164
-------
TABLE 4-18. WASTES IN EXPOSURE TESTS
Phases
Type of waste
Acidic
Alkaline
Lead
Oily
Pesticide
aln immersion
Name
"HFL"a
"HN03, HF, HOAC"b
"Slopwatera
"Spent causticb
"Low lead gas washing'
"Gasoline washwater"
"Aromatic oi 1 "°
"Oil Pord 104"b
"Weed oil3
"Weed killer"b
tests only.
bln both primary exposure and immersion
Type of waste
Acidic
Alkaline
Lead
Oil
Pesticide
.TABLE 4-19. WASTES
pH, Solids,
Name
"HFL"
"HN03, HF, HOAC"
"Slopwater"
"Spent caustic"
"Low lead gas washing"
"Gasoline washwater"
"Aromatic oil "
"Oil Pond 104"
"Weed oil"
"Weed killer"
)81endb
tests.
IN EXPOSURE
and Lead
PH
Water phase
4.8
1.5
12.0
11.3
7.2
7.*
-
7.5
2.7~
Organic
Phase
I
0
0
0
0
10.4
1.5
100
89.0
20.6
0
TESTS
Sol
Total
2.48
0.77
22.43
22.07
1.52
0.32
-
ca. 36
1.81
0.78
Water Solids
Phase Phase
II III
100 0
100 0
100 0
95.1 4.9
86.2 3.4
98.1
0 0
0 11.0
78.4 11.0
99.5 0.5
ids, % Lead,
Volatile ppm
0.9
0.12
5.09
1.61
0.53 34
0.17 11
-
ca. 31
1.00
0.46
Source: Haxo, 1980a.
165
-------
•Top Cover
Caulking
l&jjj
f
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Cooting — •*
\
t
•I
'f
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>
O '
rnfjinaf.
j
5 " 1
Waste ?
. [
t
MEMBRANE LINER -7 ',
Seam-^ 1 ^
;azak^r < •• . ' " .• .-•. • • . . ,-r ~"\~'',z
i
,^-Ste
/^'C
" ^,
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Epoxy-coated
Diaphragm
Figure 4-15. Exposure cells for membrane liners. Dimensions of the steel
tank are 10 x 15 x 13 inches in *ndth, length, and height.
-Top Cover
Epoxy
Coated
Bolt
Flanged Steel
Spacer
Waste Column :
11 Gauge Steel
I0"x I5"x i2" Hign
«l Welded
2 " Flange
Outlet tuoe witfi
Epoxy-coated
Diaphragm
Screen.
Figure 4-16. Exposure cell for thick liners.
166
-------
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completely lost its elongation and that was in exposure to a strongly acidic
waste. The CSPE, neoprene, and EPOM liners lost significant elongation in the
caustic, lead, and nitric acid wastes, respectively. The CSPE and PVC liners
stiffened during exposure to the wastes and the neoprene liner softened. The
CSPE crosslinked during exposure and the PVC probably lost plasticizer.
4.3.5.2 Immersion tests
Concurrent with the exposure of the primary liners in the bases of the cells,
supplemental membrane liner specimens were hung in the wastes. The effects of
•exposure were measured by determining the increase in weight, analyzing the
exposed specimens and measuring selected physical properties. Details of the
procedure followed in conducting the immersion tests are presented in Appendix
III-A. The effects of the immersion tests on absorption of the wastes are
shown in Table 4-22; the effects upon the elongation of the same materials are
shown in Table 4-23.
In these tables, data are presented for 12 membranes based on eight different
polymers immersed in eight different wastes from 2 to 2.2 years. Among these
membrane specimens were two CSPE membranes, two EPDM membranes, and three PVC
membranes. The oily type wastes, which included the lead waste, Oil 104,
aromatic oil, and weed oil, represented a range in aromaticity and molecular
weight. The weed oil, which is the most aggressive of the oils toward lining
materials, is a light aromatic oil. It particularly swelled the CPE and
CSPE liners. Oil 104 is a naphthenic and relatively heavy type of oil. It
had its most pronounced effect upon the butyl rubber liner. In all cases,
there was a variation between the two liners based upon the same polymer. The
differences between the two CSPE specimens was the smallest. There were
significant differences among the three PVC specimens. The effects of swel-
ling carried into the elongation of the swollen material resulting, in some
cases, in drastic reductions in this property.
4.3.5.3 Pouch test
A new test, which was devised during work on the two EPA research contracts,
appears to be a promising method for assessing the permeability and durability
of membrane liner materials in contact with wastes. At -the present time,
however, only pouches made of thermoplastic and crystalline sheetings have
been successfully fabricated and tested.
In this test, small pouches are fabricated of the membranes to be tested.
They are filled with wastes or other test fluids such as salt water, sealed
and immersed in deionized water. The permeabilities of the membranes to
water and to pollutants are determined by observing, respectively, the change
in weights of the bags and the measurements of pH and electrical conductivity
of the deionized water. Due to osmosis, water should enter the pouch and ions
and dissolved constituents should leave the bag. A schematic representation
of the pouch test showing the movement of the various constituents in shown in
Figure 4-17.
The initial tests were made with thermoplastic materials because they could be
fabricated into pouches with relative ease by heat sealing. Some of these
pouches have now 'been exposed more than 1000 days.
169
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171
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CONDUCTIVITY
0H
PLASTIC!2ER - OIL
OUTER BAG
Figure 4-17.
Schematic representation of the movements of the mobile constit-
uents in the pouch (bag) test of membrane liner materials.
Bags containing the wastes actually increased in weight, indicating the
diffusion of water into the bags through osmosis, as shown in Table 4-24. The
long-term tests now show that some ionic material is diffusing through the
liners into the deionized water.
Table 4-25 presents the interpolated or estimated times to reach an electrical
conductivity of 1000 umho for slopwater and nitric acid, both of which are
concentrated wastes. The data show the greater permeability of the PVC
lining materials as compared to Cf'E, CSPE, elasticized polyolefin, and poly-
butylene; the latter two are partially crystalline materials.
Table 4-26 presents the results of the thermoplastic membranes tested with 5%
sodium chloride solution. The data again show the greater permeability of
the PVC with respect to the CSPE and the elasticized polyolefin, which is the
most impermeable of the three. These pouches have now been taken out of the
test and physical properties of the pouch wall materials have been measured.
The results show that, within the 1150 days of exposure, there was some loss
in elongation and an increase in the stiffness of the membranes.
4.3.5.4 Tub test
Two samples of a polyolefin liner on exposure in a tub
waste failed by cracking at the folds of the sheeting.
172
that contained an oily-
This membrane was nr
-------
TABLE 4-24. RELATIVE PERMEABILITIES OF POLYMERIC MEMBRANE LINING
MATERIALS IN POUCH TEST WITH THREE WASTES3
Average flux of water into the pouch in grams per square meter per dayxlO~2
Polymer
CPE
CSPE
ELPOd
PBf
PVC
PVC
Liner
nob
86
85
36
98
19
88
Nomi nal
thickness, mils
22
33
23
• 7.5
22
20
HN03
waste
78.2
67.8
2.5
3.0
32.4
64.2
Spent
caustic
26.3
36.3
3.8
7.9
78.8
65.9
Slopwater
190. 7C
49.2
18. 4e
13.6
325.0
118.89
aExposure time is 552 days unless otherwise
noted.
Matrecon identification number
cPouch failed at 450 days.
dE1asticized polyolefin.
CPouch failed at 300 days
PB - polybutylene
gPouch failed at 40 days
TABLE 4-25. PERMEABILITY OF THERMOPLASTIC POLYMERIC MATERIALS IN
OSMOTIC POUCH TEST
Time in days for electrical conductivity of water in
outer pouch to reach 100 umho
Polymer
CPE
CSPE
ELPOb
PBC
PVC
PVC
Liner
noa
86
85
36
98
19
88
Wall of inner
thickness
mils
20
33
22
7
20
20
bag
Extractables,
%
• • •
• • •
5.5
• • •
38.9
33.9
Waste in
NH03
waste
200
500
300
600
70
110
inner bag
Slopwater
420
510
>1000
>1000
200
160
^Matrecon identification number.
bElasticized polyolefin.
CPB = polybutylene.
recommended by the manufacturer for service in a waste oil impoundment; how-
ever, in a preliminary immersion test, it had appeared to perform satisfac-
torily with the specific waste. The tub test is described in Appendix
III-B.
Specimens for this test were cut from different areas of the exposed liner:
- North side at top of tub.
- North side at waste-air interface.
173
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TABLE 4-26. POUCH TEST OF THERMOPLASTIC MEMBRANES3
Pouches filled with 5% NaCI solution
Po 1 yme r
Liner numberc
Thickness, mils.
Volatiles content of exposed pouch wall, %
Change in weight of pouch plus waste, %
CSPE
6R
32
8.7
+2.6
ELPOb
36
23
0.38
+0.71 -
PVC
59
33
0.90
+0.38
Change in weight of fluid in pouch
during exposure, % +0.95 +0.76 +0.38
Conductivity of water in outer pouch, ymho 585 34 4500
Retention of physical properties, %:
Elongation 95 100 94
S-100 106 119 120
aExposure time 1150 days (164 weeks).
bElasticized polyolefin.
cMatrecon identification number. R indicates the liner is fabric re-
inforced.
- Under waste at bottom of tub.
- South side of tub at waste-air interface.
The results of the testing of the specimens that was exposed for 43 months are
presented in Table 4-27. They snow a great variation in the effect of the
exposure, the worst being on the north side at the waste-air interface where
the losses in tensile, tear, and modulus are large.
The liner that was not exposed to :he waste, however, retained its properties
during the 43 months of exposures. These results again indicate the im-
portance of location within a waste facility as it affects the liner material.
4.3.6 The Effects of Low Concentrations of Organic Constituents
in Wastes
The ability of organic lining materials, such as asphaltic and polymeric
membrane liners, to absorb dissolved organic constituents of an aqueous
waste, even from dilute solutions, can have a highly significant effect on
long exposures upon such liners. This was observed in the case of the asphalt
concrete liner below the lead waste which contained a very low concentration
of oily material. An experiment was, therefore", performed to demonstrate the
effect of minor amounts of an organic chemical u^uri polymeric membrane liners.
Liner materials were immersed in a saturated aqueous solution of tributyl
phosphate which contained only 0.1% of tributyl phosphate. The results for a
174
-------
TABLE 4-27. EXPOSURE3 OF ELASTICIZED POLYOLEFIN AS LINER OF SMALL TUB
CONTAINING AN OILY WASTE
Variation in Location in Tub
Properties of Properties or percent retention of
unexposed properties at various locations in tub
Property
Analytical properties:
Volatiles, %
Extractables, %
Physical properties:
Thickness
/Tensile at break
^/Elongation at break
Tensile set
S-100
S-200
^Tear strength
Puncture resistance:
. Stress
Elongation
liner
0.15
5.50
23 mil
2620 psi
665 %
465 %
925 psi
1020 psi
380 ppi
26.3 Ib
0.97 in
(b)
1.65
7.54
98
84
80
92
97
95
94
119
144
(c)
6.2
32.7
112
29
63
62
49
47
41
71
132
(<*)
8.6
20.7
107
. 48
89
80
63
61
' 56
68
118
(e)
8.4
23.0
112
37
83
76
59
56
48
69
116
aForty-three months on laboratory roof in Oakland, CA.
bNorth side at top of tub.
cNorth side at waste-air interface.
^Under waste at bottom of tub.
eSouth side of tub at waste-air interface.
group of selected membranes after 17.2 months of immersion are shown in Table
4-28. The data show a great range in the weight gain of the various materials
and the corresponding effects upon properties. The weight gains ranged from
0.56% for high-density polyethylene to 107% for a thermoplastic CPE. The
effect of crosslinking in reducing swelling is shown by the crosslinked CPE
which gained considerably less in weight.
It is recognized that the tributyl phosphate can be used as a plasticizer for
a variety of materials, such as PVC. Consequently, it will swell liners of
such polymers, but not swell a butyl rubber sheeting, which is less polar and
is crosslinked. On the other hand, other organic chemicals with different
solubility parameters will affect the polymeric liners differently.
4.3.7 General Discussion of Results
The types of polymeric compounds that have- been studied in the above two
projects were described in Section 3.4.3. They are based upon the following
four types of polymers:
175
-------
TABLE 4-28
EFFECTS OF EXPOSURE ON SELECTED POLYMERIC MEMBRANE LINERS IN WATER CONTAINING
A LOW CONCENTRATION OF A DISSOLVED ORGANIC CHEMICAL3 FOR 17.2 MONTHS
Polymer
Type of compound"
Liner number
Initial thickness, mi 1
An-alytical properties:
Weight gain, %
Physical properties0:
Final thickness, mi 1
Change, %
Tensile strength, % re-
tention
Elongation at break, % re-
tention
Stress at 100% elongation,
% retention
Tear resistance, % reten-
tion
Hardness change, Durometer
points
Puncture test:
Stress, % retention
Elongation, % retention
Butyl
XL
44
63.0
21.9
64
+2
L07
115
74
• • *
-2A
73
126
CPE
TP
77
30.0
107.2
48
+60
10
155
6
14
-60A
20
127
CPE
XL
100
35.8
34.4
41
+15
63
79
46
29
-20A
85
1.25
CSPE
TP
55
33.1
31.6
38
+15
48
79
80
39
-14A
112
131
PVC
TP
59
33.1
46.2
36
+9
31
89
28
23
-33A
48
133
HOPE
CX
105
31.9
0.56
31.5
-1
88
101
92
81
-1A
101
107
a0.1% Tributyl phosphate in deioni,red water.
t>TP=thermoplastic, XL=crossl i nked, GX=partially crystalline thermoplastic.
cData for tensile, elongation, S-100, and tear are the averages of measurements
made in both machine and transverse directions.
Vulcanized elastomers, a.g. butyl rubber, neoprene, EPOM, CSPE,
CPE, ECO, nitrile rubber, blends.
Thermoplastic elastomers (TPE), e.g. CSPE, CPE, polyolefins.
Thermoplastics, e.g. plasticized PVC, PVC with selected elasto-
mers.
Crystalline polymers (thermoplastic), e.g. LDPE and HOPE.
176
-------
Note: CSPE is the identification used in the liner industry for chlorosul-
fonated polyethylene. ASTM nomenclature uses CSM.
Some of the polymers are used in both crosslinked and thermoplastic versions.
For example, lining materials of CSPE and EPDM have been manufactured in both
crosslinked and thermoplastic versions.
On exposure to fluids, most polymeric materials, whether they are crosslinked
or not, will tend to swell and change in some properties. The major factors
involved in the swelling of polymeric materials are:
- Solubility parameter.
- Crosslinking of polymer.
- Crystallinity of polymer.
- Chemical stability.
- Soluble constituents in compound.
The solubility parameter is used by polymer scientists to measure the
similarity in chemical characteristics of the polymer such as is in the
lining material, with a fluid with which it is in contact (Hildebrand and
Scott, 1950). For example, a nonvulcanized hydrocarbon rubber, such as
natural rubber, will swell and dissolve in a hydrocarbon such as gasoline. On
the other hand, a highly polar polymer, such as polyvinyl chloride or nitrile
rubber, does not dissolve in gasoline.
Crosslinking a polymer or a rubber reduces its ability to swell in a solvent.
Polymer scientists use the swelling of a crosslinked rubber as a measure of
the degree of crosslinking: the greater the crosslinking, the less the
swelling. This effect is pronounced in such rubbers as CSPE and CPE, liners
of which are available in both vulcanized and unvulcanized forms.
Crystallinity of a polymer acts much like crosslinking to reduce the ability
of a polymer to'dissolve. Highly crystalline polymers, such as high-density
polyethylene, will not dissolve in gasoline, even though they are basically
similar in chemical composition. Such high density polymers are finding
considerable use in containers for a wide range of solvents and chemicals and
have recently been introduced as lining materials.
Chemical stability means that the polymer does not degrade on aging which
would result principally in reducing its molecular weight causing swelling
and dissolving.
Soluble constituents in a polymeric compound can have a strong bearing on the
swelling of that material. Most polymers contain minor amounts of solubles,
e.g. salt, which are introduced during their manufacture. Soluble constitu-
ents can also be introduced into the compound from the compounding ingredients.
The swelling is a result of the diffusion of water into the compound.
The effects that the first three factors have on the swelling of liner
materials is illustrated in Figure 4-18. The swelling of the thermoplastic
type of material in a fluid with which it fs somewhat compatible is represent-
ed in Curve A, which indicates that the material will continue to swell with
time and that no real plateau is reached.
177
-------
o
z
LU
CO
TIME
Figure 4-18.
Types of swelling of polymeric membranes. A is the charac-
teristic swelling of a thermoplastic polymer whose solubility
parameter is close to that of the liquid. B is characteristic
of a vulcanized or crystalline material. C is characteristic of
a thermoplastic containing a plasticizer.
The swelling of crosslinked material is represented in Curve B,
swelling reaches a plateau and changes only slightly with time.
the plateau is determined by the degree of crosslinking and by
solubility parameters of the waste fluid and the polymer,.
in which the
The level of
the relative
Curve C represents a plasticized :hermop.lastic or a oil-extended rubber in
which tne plasticizer is leached from the polymer. In this case, there is an
'initial swelling and then a reduction in swelling. In some cases, there can
be a shrinkage of the liner due to the loss of plasticizer or oil. The
effects on the physical properties of these exposures have been indicated in
the above sections. The swelling will result principally in the softening of
the material, possibly in its dissolving, and in increased permeability.
In selecting polymer and rubber compounds for service in a liquid medium, a
designer generally selects materials which have low or negligible swell.
Swelling of a compound can have adverse effects which will make the product
unserviceable. Some of the major effects of swelling generally are:
- Softening.
- Loss or tensile and mechanical strength.
- Loss of elongation.
- Increased permeability.
- Increased potential of creep.
- Greater susceptibility to polymer degradation.
178
-------
All of these effects are adverse with respect to liner performance. Swelling,
therefore, is a valuable indicator of the compatibility of a liner to a
waste.
Shrinkage can also be a measure of compatibility for liner compositions that
are highly plasticized. For example, in the case of highly plasticized PVC
compounds, the plasticizer can leach and diffuse out of the polymer leaving
the compound stiff and brittle.
4.'4 EFFECT OF WASTE FLUIDS ON ADMIX AND OTHER LINER MATERIALS
As a part of the two liner research programs described in the above section, a
variety of soils and admix liner materials were exposed to the same waste
fluids. The results of these tests, after limited exposure, are described in
the next two subsectons.
4.4.1. Exposure to Municipal Solid Waste Leachate
After one year of exposure to leachate, the asphalt concrete and soil asphalt
liners lost drastically in their compressive strengths; however, they maintain-
ed their impermeabi1ity' to leachate. The asphalt binder, which normally
hardens on aging in air, became softer indicating possible absorption of
organic components from the leachate.
The soil cement liner lost some of its compressive strength; however, it
hardened considerably during the exposure period and cored like a Portland
coment concrete. It became less permeable during the exposure period.
Inhomogeneities in the admix materials, which probably caused the leakage in
paving asphalt concrete and soil asphalt liners, indicate the need for con-
siderably thicker liners than were used in the experiment described in this
chapter. Thicknesses of two to four inches were selected for the experiment
to give an accelerated test and were designed with an appropriately-sized
aggregate. The same compositions in the second set of 12 liners did not leak
after 27 months of exposure.
The asphalt membranes withstood the leachate for one year, although they did
swell slightly. There was no indication of disintegration or dissolving of
the asphalt.
4.4.2 Exposure to Hazardous Wastes
Five types of admix materials are being studied in this ongoing project:
- Compacted fine-grain native soil.
- Soil cement.
- Modified bentonite in sand.
- Hydraulic asphalt concrete.
- Membrane based on emulsified asphalt on a nonwoven fabric.
Because of the incompatibility of some of the wastes with particular admix
materials, several combinations were deleted. The only liner material that
179
-------
was placed below the acid waste: was the hydraulic asphalt concrete. Neither
of the two oily wastes was placed on the asphaltic liners; however, the lead
waste, which contained a light, oily fraction, was placed on these liners.
The performance of the individual admix liners is discussed below:
Compacted fine-grain soil. All of the wastes, except the nitric acid waste,
were placed above the compacted fine-grain soil liner. Seepage below all of
the liners took place. The amount of seepage was measured and the respective
pH, conductivity, and percent total solids were determined. The following
observations are made with respect to the seepages through the soil liners:
a. The rate of seepage is 10"8 to 10"7 cm sec"1 which compares favor-
ably with the permeability of the soil measured in the laboratory
permeameter. There is some variation in the amount of seepage collect-
ed below the liner which may reflect permeability differences, perhaps
due to density of the soil.
b. The fluids being collected after more than three years of exposure
still continue to be essentially neutral and to have high solids content
(mostly salt) and electrical conductivity.
c. There is a downward trend in solids content of the seepages collected
under the pesticide and lead wastes, but the seepage under the spent
caustic waste continues to be 23% solids.
One set of the soil liners was removed and tested. The permeability of a
specimen taken from the cell cortaining the soil and the aromatic oil waste
was determined using a "back-pressure" permeameter (Vallerga and Hicks, 1968).
The sample was collected from a depth of seven to ten inches below the surface
of the soil, i.e. from that part of the soil which was not penetrated by the
oil. The three consecutive values obtained were: 1.83 x 10~°, 2.43 x 10"^,
and 2.60 x 10"8 cm sec. These figures indicate the low permeability of the
soil, which had a bulk density af 1.318 g cm~^ and a saturation degree of
101%.
Analyses for trace metals were made of the soils which .were below the lead
waste, Oil 104, and the aromatic oil. The testing included determination of
pH and heavy metal content (cadmium, chromium, copper, magnesium, nickel, and
lead) on samples collected at different depths in the cells.
With the exception of the liner exposed to spent caustic, the pH of the soil
liner was not significantly altered by the wastes. The pH of these samples
was in the range of 7.0 to 7.6; the ratio, soi1 rsolution, was 1:2 with
0.01 N CaCl? being the equilibration solution.
In the case of the spent caustic, the pH values were around 9.0 for samp.les
collected in the first two to three centimeters, which concurs with our
previous findings that, over the exposure period of 30 months, the wetting
front of the wastes penetrated the soil .to .a ,depth of only three to five
centimeters.
The heavy metals distribution, as indicated by the analysis, shows, in the
case of the lead, only a shallow contamination of the soil. Similar results
180
-------
were obtained on all six heavy metals in the case of the soil below the Oil
104 waste.
Soil cement. All of the wastes except the acid waste were placed on the soil
cement liner. No seepage occurred through the liner during the 30 months of
exposure.
One set of the soil cement lining materials was recovered after 625 days of
exposure to the various wastes and the individual linings were cored and
tested for compressive strength. In all cases, compressive strength of the
.exposed soil cement was greater than that of the unexposed material. There
was some blistering of the epoxy asphalt coating which was applied to one-
half the surface of each specimen.
Modified Bentonite and Sand. Two types of modified bentonites were used as
1iners in ten eel Is. One type allowed somewhat less seepage than the other.
There was measurable seepage in seven of the ten cells and one failed allowing
the waste (Oil 104) to come through the liner.
Irrespective of the type of waste above the liner, the quality of the seepage
was not greatly different among the samples collected. For example, the
seepages collected below the pesticide waste on both types of modified ben-
tonite liners were similar.
When the spacers containing the bentonite-sand were sampled, it was found that
there had been considerable channeling of the wastes into these liners. There
was no channeling at the walls of the spacers.
This type of liner is probably not satisfactory for these types of waste. The
use of a soil cover on the bentonite layer to produce an overburden would
probably reduce the channeling effect.
Hydraulic Asphalt Concrete. Liner specimens of hydraulic asphalt concrete
were placed under four of the wastes. Excluded were the oily wastes.
This lining material functioned satisfactorily under the pesticide and spent
caustic wastes, but failed beneath the nitric acid waste. However, the
failure arose primarily from the failure of the aggregate which contained
calcium carbonate; also, the asphalt was hardened considerably.
In the case of the lead waste, the asphalt absorbed much of the oily constitu-
ents of the waste and became "mushy". There was some staining of the gravel
below the asphalt liner.
Duplicate cells containing the hydraulic asphalt concrete and the lead waste
are still functioning without seepage.
Membrane Based on Emulsified Asphalt and Nonwoven Fabric. This membrane was
placed under only three of the six wastes: pesticide, spent caustic, and
lead. The acid waste was excluded because b'f the severe hardening it caused
the asphalt, and the oil wastes were excluded because of the high mutual
solubility of the asphalt and the wastes.
181
-------
The asphalt membrane functioned satisfactorily with the pesticide and spent
caustic wastes; however, when the cell containing the lead waste was dismantl-
ed, the gravel below the liner was wet and stained brown. This result indi-
cates that some seepage took place.
4.5 COMPATIBILITY OF LINER MATERIALS IN WASTE FLUIDS
4.5.1 Introduction
In Chapter 2 various wastes that must be contained are discussed with par-
ticular reference to their aggressiveness to different lining materials. In
Chapter 3, liner materials which are candidates for the lining of waste
disposal facilities are described and discussed with respect to their compo-
sition and characteristics.
The compatibility of a liner with a specific waste is one of the first consid-
erations that a designer has i ri planning a specific landfill site. The
designer of a lined waste disposal site must decide which liner material
of those he has available can effectively contain the particular waste over
the needed length of time. In some cases, the requirement will be for extend-
ed lengths of time, such as would be encountered in landfills. The designer
must determine what liner materials are compatible with the wastes that must
be contained.
It is the objective of this section to summarize some of the information on
the wastes and the liners presented in Chapters 2 and 3 and to describe the
approach and methodology of determining the compatibility of liners with given
wastes.
4.5.2 Screening of Liner Materials Based upon the State-of-the-Art
Knowledge
Although the direct experience of compatibility of liners and wastes based
upon actual experience is limited, there is a vast amount of information
available from the chemical and petroleum industries, soils science, materials
science, polymer science and technology, containers industry, coatings indus-
try, etc., from which the engineer and designer can draw to assess compatibil-
ity of given materials with wastes. The technology involving the use of
materials for the lining of waste disposal facilities is relatively new. It
must depend on the experience of other technologies while it is developing and
obtaining experience.
In this section the initial screening of liners based upon the available
knowledge is described.
4.5.2.1 Characterizing the waste
As has been indicated in Chapter 2, the waste flui.ds that are in the waste or
are leached from the waste can be highly complex materials usually containing
water and a wide range of inorganic and organic dissolved constituents.
Individually, most of the constituents are well characterized. The diffi-
culty with waste fluids is that they are complex blends containing components
182
-------
that can be toxic and also affect lining materials in a variety of ways.
Also, the waste fluid can be highly -concentrated and relatively simple,
such as would occur in a spill. The analytical capabilities have developed
greatly in recent years, therefore, an accurate compositional analysis can
generally be made of a waste fluid. The designer must characterize the waste
by obtaining an analysis to determine its major constituents. With these data
he can make a first estimate of the kind of a liner which must be avoided.
For example, oily wastes generally degrade asphalts and many polymeric
materials. Soils, though very effective with water, may interact with ionic
components such as calcium or, in some cases, some of the organic solvents.
The characterization of the waste should focus on those waste properties which
are potentially damaging to liners described in this study. The following is
a partial listing of waste constituents which can adversely affect one or more
of the 1iners:
- High pH, greater than 10.
- Low pH, lower than 3.5.
- Oily wastes.
- High temperature.
- Presence of exchangeable ions, e.g. calcium.
- Organic bases and acids.
- Organic compounds, in general.
4.5.2.2 Characterizing the liner materials available
As discussed in Chapter 3, the range of materials which could be used to line
disposal sites is large and covers a wide range of types, from soils and
admixes to membranes of many kinds. As the soil at the site would probably be
a candidate liner, it should be thoroughly investigated with respect to
its character, not only as to permeability, but also with respect to compati-
bility with the waste that might be placed on it.
The effects of various salts and chemicals upon soils are known from the
agricultural science and, to some extent, from chemical science. From the
polymer industry there is considerable information available on the use
of polymeric materials for the lining of many pipes, reactors, gaskets, etc.
which function in nonaqueous media, acids, bases, etc. Generally, these
liquids are simple, that is the number of constituents are few. However,
there is wide experience with handling these various materials. Many plastics
and rubbers are used in outdoor applications and much information is available
with respect to their durability and weatherability. Considering the avail-
able liner materials, it is quite possible that some can be eliminated when
considering the waste that must be contained.
4.5.2.3 Matrix of liner materials-waste compatibilities
Out of experience to date, matrixes of wastes and liners can be considered to
Indicate the general compatibility of some of the materials. An example of
this is in Table 4-29 which shows the range of types of liner materials and a
variety of industrial and hazardous wastes. In all cases, neither the types
of liner materials nor the types of wastes are specific. Each has a range of
183
-------
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compositions and characteristics. A rating of "good" indicates tnat the
combination is probably satisfactory; "fair" indicates the combination should
be tested, and "poor" indicates the combination should be avoided. This table
functions only as an initial guide and, in many cases, specific combinations
of liner materials and wastes must be tested before selecting acceptable liner
materials. This is the subject of the next section.
4.5.3. Testing of Specific Combinations of Liners and Wastes
As indicated in the previous section, knowledge of the wastes to be contained
and the lining materials available can be used to make an initial screening of
specific lining materials which might be suitaoie for containing the wastes.
In some cases this knowledge may be sufficient to make a choice, particularly
if the waste does not contain components aggressive toward liners. Generally,
a compatibility test should be performed before a specific liner is selected.
4.5.3.1 Sampling and analyses of wastes for compatibility
tests
In order to run accurate compatibility tests of lining materials, a represent-
ative sample of the waste must be obtained. In as much as wastes are general-
ly highly complex and heterogeneous, there is a major problem in obtaining
representative samples. In some cases samples of the specific waste may not
be available and similar types of wastes must be used. Furtnermore, consid-
eration must be given to the fact that over the period of time that an
impoundment may be operating, there may be a change in the composition of the
wastes.
4.5.3.2 Compatibility testing of soils
Testing, of candidate soils for use as the liner for a specific waste impound-
ment is necessary to determine chemical sensitivity to the waste. The effect
of the waste upon permeability of soils is the most relevant as indicated in
Section 4.2. A recommended test method is described in Appendix III-C.
4.5.3.3 Polymeric materials
Individual types of tests have been found useful in assessing the effects of
the wastes upon lining materials. These are:
- Immersion test.
- Tub test.
- Pouch test (limited to thermoplastics and crystalline materials).
The first two of these tests are described in detail in Appendixes III-A and
III-B, respectively.
Immersion Test. In this test samples of the specific membrane liners are
immersed in the waste and the effects of the immersion upon the weight and
dimensions of the liner specimens and a selected" number of physical properties
are measured as a function of immersion time. By immersing the samples
totally in the waste fluid, a somewhat accelerated test is generated. Further
185
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acceleration can be effected by increasing the temperature somewhat. However,
the closer the temperature and exposure conditions are to actual service, the
more reliable the results will be. Also, the longer the test can be run, the
more reliable it will be. These types of tests should be initiated early in
the design phase of the waste facility. An exposure period of twelve months
is desirable. Samples can be withdrawn at one, two, four, etc., months to
assess the effect as a function of time.
Ppuch Test. This test was designed to measure the permeability of polymeric
membrane liner materials to water and to dissolved constituents of the wastes.
A sample of the waste is sealed in a small pouch fabricated of the liner
material under test which is then placed in distilled or deionized water.
Measurements are taken periodically to determine the extent of movement of
water into the membrane and/or leakage of waste into the water. A concentra-
tion gradient is created by the deionized water on one side of the membrane
and the waste on the other side. This test environment results in the move-
ment by osmosis of water and ions and other dissolved constituents through the
membrane due to the differences in concentrations on either side of the
membrane. Changes in liner materials are observed and later physical proper-
ties are tested. At present, this test is limited to thermoplastic and
crystalline membranes; however, it can be used to asses the compatibility of
wastes with these materials.
Tub Test. The purpose of this test is to evaluate flexible membrane liner
materials under conditions which simulate those that occur in actual service.
The effects of exposure to the sun, temperature changes, ozone, and other
weather factors can be evaluated as well as the effect of a given waste on a
specific liner. The fluctuation of the level of the waste is particularly
significant in that a horizontal section of the liner is subjected to the
effects of both the waste and weather. This alternating of conditions is
especially harsh on liner materials and is usually encountered in the field.
4.6 FAILURE MECHANISMS AND ESTIMATING SERVICE LIVES
An important factor in selecting liner material for a given disposal facility
is to match the required life of the waste impoundment with the estimated
service life that can be anticipated for a given liner in the particular
exposure condition. It is recognized that there can be a range in the lives
that are needed. For ultimate disposal of a waste, very long times are
required during which a liner must maintain its integrity and function as
designed. On the other hand, for temporary holding ponds, much shorter lives
are satisfactory.,. Furthermore, the life of a liner will depend upon the waste
which it' contains.
In order to make estimates of the service lives, it is necessary to know how
the liner system might fail. In Section 4.2 the various failure mechanisms
relating to clay soil liners are described and discussed. The effects of a
variety of wastes on soils are described with particular reference to
their loss in permeability and in strength resulting from the effects of
chemical species on the soils.
The effects of various wastes on polymeric membrane and admix liner materials
are described in Sections 4.4 and 4.5 respectively. Some of the effects
186
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appear to be severe enough to cause a liner to fail if the exposure is suffi-
ciently long.
The experience in the field with membrane type liners and liners in general
has been primarily for reservoirs and other water containment facilities. The
failure type mechanisms that have been encountered are described by Kays
(1977). An amplification of the subject of failure mechanisms and estimating
service life will be forthcoming in revisions of this Technical Resource
Document.
This section describes and discusses the categories and characteristics of
the failures of liners in the service environment. The objective of this
section is to enable the user of this manual to understand and identify
liner failures and the events leading to failure. The three major categories
of liner failure that will be discussed in this subsection are physical,
biological, and chemical. Table 4-30 is a listing of the principal failure
mechanisims in liners.
Failure of liners include problems in the subgrade, the lining material
itself, forces of weather and aging, and problems imposed by operating
procedures on condition. The problems in subgrades are related to compaction,
differential settling, slope sloughing, built-up hydrostatic and gas pres-
sures. Failures may.be induced by.chemical and/or physical circumstances.
Chemical compatibility failures are a function of the waste-liner combina-
tion, while physical failures are more often subgrade related.
4.6.1 Physical Failures
There are several modes of liner failure due to physical processes and stres-
ses, each of which is described in- the following paragraphs. Each particular
failure mode may or may not apply to every type of liner. However, notable
examples will be presented where warranted.
TABLE 4-30. FAILURE CATEGORIES
Physical Biological Chemical
Puncture Microbial attack Ultraviolet attack
Tear Ozone attack
Creep Hydrolysis
Freeze-thaw cracking Ionic species attack
Wet-dry cracking Extraction
Differential settling Ionic species incom-
patibility
Thermal stress Solvents
Hydrostatic pressure .. ......
Abrasion
187
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4.6.1.1 Puncture
Puncture failure would most commonly occur in membrane liners; however, such
failure can occur in the other types of liners under specific circumstances.
Puncture failure of membrane liners due to sharp angular rocks in the subgrade
that have become exposed to the liner because soil fines migrated downward
over time is a major concern. Puncture from operations, man or vehicular, is
of concern but can largely be mitigated through good operation procedures.
Burrowing animals and hoofed animals seeking water can also cause puncture.
4.6.1.2 Tear
Tear failure is similar to puncture failure in its occurrence. Because of a
membrane's relative thinness compared to soils, clays, asphalts and other
liners, its resistance to fai'ure in that dimension is correspondingly
reduced. Localized structural tear failure can result from several stress-
relaxation-stress cycles in which the liner is losing strength or it stretched
with each cycle. Tear, like puncture, can occur due to operations or animals.
4.6.1.3 Creep
Creep is the common term used to describe increasing deformation of a material
under sustained load. The main factors which influence creep failure are
material microstructure, stress level and temperature. The significance of
this type of failure is that it i •; difficult to detect and control. Cr*eep can
occur with any liner material.
4.6.1..4 Freeze-thaw cracking
Cycles of freezing and thawing cause material cracking which leads to failure
by volume expansion of liquids in pore spaces during freezing. This expansion
increases .pore space volume and the accessibility of liquids to the pore space
volumes. In addition, the freeze-thaw cycle will not be a localized failure
at a facility, but will occur throughout. Proper planning and design is
essential to mitigate this type of failure in areas where freezing is a major
concern.
4.6.1.5 Wet-dry cracking
This mode of failure is most commmonly found when clay liners are used. The
wet-dry cycles cause alternate expansion and shrinkage of clay liners which
decrease the strength of the liner and increase its overall effective permea-
bility. Because soil materials have poor tensile strength, the shrinkage
caused by drying is highly disruptive to the cohesive structure of clays.
Other liners are adversely affected by wet-dry cracking, but to a lesser
extent.
4.6.1.6 Differential settling - •-
Differential settling can damage till liners. This problem is best mitigated
with a thorough geologic analysis prior to site selection and careful subgrade
design and construction. Differential settling i-s a localized structural
188
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stress phenomenon and the greater the thickness and elasticity of the liner,
the greater the tolerance range for differential settlement.
4.6.1.7 Thermal stress
Thermal stress results from differential temperatures through a material or
when temperature change is sufficent to cause a phase change in a material.
This temperature change (especially in polymeric membranes) can cause volume
changes by thermal expansion (or contraction) as the case may be, or by phase
changes. Thermal stress may also become significant in light of the different
reaction rates produced by individual components of a composite material.
Phase changes in solid materials caused by heat, generally cause stress
because different phases usually have different volumes per unit weight.
•Thermal stress can be controlled or tolerated by allowing for expansion or
contraction in design, stress relief, or an acceptable range of variation.
However, if the stress is great enough, cracks will occur. All asphalt liners
are highly susceptible to temperature. Polymeric membrane liners are also
temperature sensitive, but to a lesser degree.
4.6.1.8 Hydrostatic pressure
Hydrostatic pressure is of concern when the structural support of a subgrade
or base material is lost by piping, sinkholes, oxidation of organic material,
settlement, etc. The effect of hydrostatic pressure exerted beneath a liner,
which is due to inadequate drainage below the liner, is discussed in Chapter
5.
4.6.1.9 Abrasion
The continuous or near continuous action of abrasion on a liner has a signifi-
cant wearing effect over time. Windborne abrasion is a serious consid-
eration. In arid regions, sand particles carried by the wind have a
sandblasting effect on the liner. Liners with high abrasion resistance must
be specified, or a protective cover must be placed on the exposed berms.
Runoff entering the pond from the surrounding topography may contain sticks,
branches, rocks, and other debris which could abrade, tear, or even puncture
the liner. Construction of a diversion channel to handle runoff will avoid the
potential problems.
4.6.2 Biological Failures
The major emphasis on biologically induced failure is microbial attack in
which the microbes "eat" the material and damage or destroy its structural
integrity and low seepage characteristics. Particularly susceptible to
biological attack are the plasticizers that are used in some polymer com-
pounds. Bactericides are sometimes used to counteract this type of failure.
4.6.3 Chemical Failures .. .
Because organic and inorganic chemicals constitute a great majority of the
hazardous wastes to be contained in lined waste impoundment facilities,
189
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chemical failures are of great importance and significance. The following^
paragraphs describe the various types of chemical failures. ^
4.6.3.1 Swelling
The most serious chemical effect to polymeric liners at waste disposal facili-
ties is that of swelling which is discussed in detail in Section 4.3.7.
Potentially, sufficient swelling can cause loss in strength, elongation, creep
and flow, and loss in puncture resistance. Failures of these types are most
apparent when the liner is in direct contact with the wastes.
4.6.3.2 Extraction
Liner materials such as polyvinyl chloride which contain large amounts of
monomeric plasticizer are highly susceptible to extraction of the plasticizer.
Such extraction can result in embrittlement and shrinkage and possibly
breakage of the liner. This effect is also discussed in Section 4.3.7.
4.6.3.3 Outdoor exposure
Exposed polymeric linings can be subject to failure from heat and infrared,
ultraviolet light, oxygen, ozone, and moisture. The factors generally
operate in combination, with tre presence of oxygen and moisture being the
major contributing factors. Failure of the liner generally occcurs from
embrittlement, shrinkage and breakage. Ozone can cause cracking of many
polymers, particularly those which contain some unsaturation. Failures of
this type occur in areas where the rubber sheeting is stretched. m
Considerable information is available on the durability and service lives of
exposed lining materials in which the principal environmental conditions are
ultraviolet light, oxygen, ozone, heat, and wind (Strong, 1980).
190
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CHAPTER 5
DESIGN AND CONSTRUCTION OF LINED WASTE FACILITIES
5.1 INTRODUCTION
This chapter discusses the planning, design, and construction of lined facili-
ties for waste storage and impoundment with particular regard to the design
and construction of the lining. The discussion in this chapter provides
site selection background, even though it is assumed that the site has been
selected, and presents design and construction guidelines of the best avail-
able engineering practice in liner technology. A detailed description of
the installation of flexible membrane liners and the leachate collection
systems is presented in Appendixes IV and V, respectively.
A critical aspect of each liner installation is adequate quality control of
materials and workmanship. Ideally, the quality control function would be
performed for the owner by a party independent of the liner manufacturer,
fabricator, installer, and earthwork contractor. That party should be respon-
sible only to the owner of the facility. The owner should then be able
to certify to a regulatory agency that the facility was constructed as
planned. Often a quality control function is not included as part of a design
and construction program. As a minimum, the owner or person ultimately
responsible for the operation of the lined facility must check the quality of
the materials and installation workmanship on the job site before accepting
the finished product.
In this chapter the design and construction of liners of the following mate-
rials wil1 be described:
a. Soils and clays
b. Admixed materials
t
c. Flexible membranes
d. Sprayed~on, soil sealant, and chemisorptive materials.
The design and construction of the final covers is discussed in a separate
Technical Resource Document, SW 867 (Lutton, 1982).
Lined impoundments have several specific end uses', each with its own partic-
ular objectives and period of performance. A lined waste impoundment can be a
pond, a landfill for hazardous waste, or a sanitary landfill. The reasons for
the use of a liner or liners range from groundwater protection to resource
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recovery to improved reliability. Depending upon the type(s) of waste, the
period of containment, the surrounding climatic conditions, the available
native soil and geologic structure, the geohydrologic characteristics, and
several other factors, the selection, design, and construction of a lined
waste impoundment can easily become a complex and intricate procedure. The
waste characteristics significantly influence the choice of liner type, as
does the purpose of the containment. If the facility is short term or temp-
orary in its function, i.e. the waste is to be stored for a period of time and
then excavated or transferred elsewhere, the selected liner component will be
quite different from a facility which is proposed for permanent disposal of
waste.
5.1.1 Types of Constructed Impoundments
The three major categories of new impoundment installations are as follows:
(1) totally excavated; (2) filled; and (3) combination. Excavated impoundments
are those which are dug from a surface (Figure 5-1) such that the major
portion of the capacity is below the grade of the surrounding land surface.
Filled impoundments are built up above grade such that the large majority of
the capacity is at an elevation higher than the immediate surroundings.
Combination impoundments result when material is both excavated and filled
(Figure 5-2).
Excavated impoundments are found primarily in relatively flat areas where
loose soil of a suitable nature (alluvium, for example) exists. 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 u-sed for
daily cover if the impoundment is a municipal solid waste landfill, for
general grading, or for fill in other construction activities.
In some instances, bedrock is encountered before excavation of the impoundment
is completed, thus necessitating blasting and rock removal. The economics of
storage, containment, land, excavation difficulty, material use, and other
considerations must be systematically analyzed before selecting the overall
impoundment design.
Filled impoundments are frequently constructed at sites with bedrock near or
at the surface because the cost of blasting and excavating precludes excavated
impoundments in all but extreme cases. High groundwater table and capillary
zones are other frequent reasons for this type of construction. Where local
geologic considerations preclude the economical construction of excavated
impoundments, the desirable earth materials (sand, silt or clay) for berm and
bottom construction are often hauled in from off-site locations. A special
type of filled impoundment is one built in an existing valley. An earthen dike
is constructed between the valley walls and across the valley floor (Figure
5-3). Earth materials are used to prepare the sides and bottoms of the
impoundment prior to liner installation. Care must be taken in valley span
facilities to account for both surface and subsurface runoff and take appro-
priate measures to manage the flow.
Most impoundments can be classified as combination excavation-fill impound-
ments. A balanced cut-fill project will usually result in the best economics.
The designer should recognize that the upper 3 to 12 inches of topsoil should
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Figure 5-1. An excavated impoundment (EPRI, 1979).
Figure 5-2. Diked pond partially excavated below grade (EPRI, 1979).
204
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Figure 5-3. A cross-valley pond confiyuration (EPRI, 1979).
be removed for use elsewhere and that the soil excavated may shrink 5 to 20
percent between excavation-and placement in an engineered fill.
The excavated material will be used to build side walls, berms, basal areas,
and for miscellaneous construction needs. The fill soils are molded by the
engineering contractor to the desired grades, and physical and mechanical
characteristics established by the project plans and specifications. If the
material at the site within the confines of the planned impoundment meets the
needed design/construction constraints, then time and money can be saved by
using the immediately available material in .subsequent construction activ-
ities.
5.1.2 Site Planning Considerations
The construction, successful completion, and desired finished characteristics
of an impoundment can be greatly influenced by the site chosen for its loca-
tion. The selection of a site depends upon many factors. Table 5-1 is a list
of factors which should be considered in the site planning/construction
process. The design of most impoundments is controlled by the type of waste to
be impounded and the type of facility which the impoundment will serve. Table
5-2 provides a checklist of important data the designer must assemble and
evaluate before beginning to design a waste disposal facility at a specific
site.
5:2 DISPOSAL FACILITIES WITH LINERS OF SOILS AND CLAYS
Unlike other engineering works in which manufactured structural materials with
code-prescribed properties are used, in the case of soil-liner construction
there is often an economical need to use the existing in-place soil material.
This is the situation if a prior analysis has proven the soil material to be
an acceptable material for being "improved" as a liner.
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TABLE 5-1. FACTORS TO BE CONSIDERED IN THE SITE PUNNING/
CONSTRUCTION PROCESS
Characteristics of the waste to be impounded
Characteristics of soil materials
Subgrade characteristics from soil borings
Desired characteristics of bottom and side surfaces
Location of bedrock
Stability of materials
Drainage considerations
Impoundment dimensions
Wind direction and velocity
Ambient temperature
Gas venting
Local vegetation
Floor considerations
Berm width requirements
Inflow/outf1ow/overf1ow conveyances
Monitoring/leak detection systems
Cover material aval 1abi1ity/characteristics
Proximity to major waste generators
Proximity to residential and commercial areas
Coupon testing and evaluation, if applicable
Weed control
Location of groundwater and capillary zones
Presence of indigenous burrowing animals
Fencing requirement and access
5.2.1 General Discussion
Because of soil variability and tie scale of the operation in designing and
constructing a soil liner, relatively more flexibility must be provided by the
designer in the specifications required. These speci fi cations 'should be
both essential and operational and should be stated in terms of performance
required from the soil liner and in terms of methods of achieving the required
performance.
A very important feature of the construction operation of a soil liner is the
inspection of the adequacy of ttie work performed. This is done by visual
observation and testing. Although a large amount of experience has been
accumulated, in constructing similar structures, e.g. dams, canals, embank-
ments, etc. relatively little is known about the construction of soil liners
of large areas; accordingly, the quality control function should be given a
high priority. The inspection work should be -performed during construction
and the amount of effective inspecting work will depend on 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.
i 206
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TABLE 5-2. RELEVANT BACKGROUND INFORMATION HELPFUL
DURING SITE SELECTION PROCESS
~USER INFORMATION
Owner's name
Owner's location and telephone number
Design engineer
Operator's name
Site and facility location
METEOROLOGICAL DATA
Temperature - high, average, low
Wind direction, velocity
Precipitation - snow, hail
PROCESS DATA
Waste description
Relevant waste characteristics
pH
Temperature
Composition of waste
% Solids
Quantity
Unusual variations, e.g. loading, chemicals, temperature
FACILITY NEEDS AND CHARACTERISTICS
Capacity
Dimensions
Longevity
Harvesting or reclamation program(s)
Aeration program - equipment and methods
Waste flow variation and discharge velocity
Inlet system
Outlet system
Venting systems
Lining penetrations
Regulatory agencies
Names
Addresses
Monitoring requirements
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To assist the inspection operation, a field laboratory should exist, or
better, access to a qualified laboratory should be available. The effort
should be such that, at any time during the construction of the soil liner, a
clear qualitative assessment can be made as to whether the work performed
complies with the specification.
Heterogeneity of soil is the rule rather than the exception; it is "the nature
of the beast". The design specifications, based on all pertinent information,
must provide the contractor who performs the site improvement (the construc-
tion of the soil liner) with all needed information. The specifications
should state clearly the working procedures for every type of soil or unit so
that the end result will be a uniform soil liner.
The working procedures indicated in the design specifications for a par-
ticular soil unit normally would be easy to observe if the soil cover were to
have a uniform moisture content and density characterization in the undis-
turbed state; oftentimes, though, there is a soil intraunit heterogeneity
which can escape observation during the reconnaissance investigation.
The construction of a soil liner is the field operation in which in-place or
imported soil material is compacted and remolded such that the seepage through
it is restricted. The most important purpose in producing such a blanket is
to impede waste-effluent flow. Since this is done by soil densification, the
contractor and the quality control should have to provide evidence that:
a. The design density is achieved.
b. At these density specifications, the soil has indeed the designed
flow properties.
The highest priority of the quality control has to be in checking item
(a); the quality control group shojld cooperate fully with the designing group
in assisting the investigations in item (b).
The operational specifications refer to the following:
a. The depth of the soil liner.
b. The moisture-content of the soil to produce the desired density.
c. The depth of the unit-layer to be compacted at one time.
d. The number of passes of the compacting implement over one unit-
layer.
e. The weight of the compacting implement.
f. The type of compacting implement.
g. Possibly the trade-name of the compacting implement.
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All these operational specifications have to be rigorously observed by the
constructing team.
5.2.2 Testing of Soil for Selection and Design of Liner
The principal requirements that a soil must meet for use as a liner for
waste disposal facilities are:
a. Low permeability to water and waste fluids.
b. Little or no interaction with the wastes which might increase perm-
eabi1ity.
c. Absorptive capacity for pollutant species.
d. Strength initially and after contact with waste fluids to maintain
slope stability.
In addition to the above principal soil requirements, the history of the
candidate soil must be -investigated to determine its prior use or exposure to
hazardous, toxic or other undesirable elements which might affect the function
of the waste impoundment facility. For example, monitoring the performance of
a liner constructed with soil contaminated with a toxic substance would very-
likely show that substance below the liner at some point in time, even though
the liner was functioning properly, and that particular substance had
never been placed in the impoundment facility. This study of the subgrade
soil may require chemical analysis of the soil and the pore water therein.
This subsection is concerned with the laboratory testing of the candidate
soils for possible use as a liner at a particular waste disposal facility.
This testing should be incorporated in the soil selection process and in
designing of the liner to insure the adequacy of the soil selected and to form
the basis of the design.
5.2.2.1 Atterberg limits
The determination of liquid and plastic limits is essential for both classifi-
cation purposes and behavioral assessments (Section 3.2.3.1). The liquid limit
of soils should be determined by ASTM D423 and the plastic limit and plastic-
ity index by ASTM 0424 for classification purposes.
If reasons exist to suspect that the soil is sensitive to the chemical compo-
sition of the waste fluid, one may wish to perform a compaction study. Two
variables should be considered: (1) the seasoning period, i.e. the length of
time in which the soil is cured with water and, (2) the chemical composition
of the fluid used. If, in comparison with distilled water, a 0.01 N CaSO^
solution produces drastic changes in plastic properties, a waste leachate
should be obtained and used in determining the" limits. The generated results
should constitute the starting point for the investigation of flow, volume
change, and strength characteristics of soils.
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5.2.2.2 Determination of moisture-density relationships
In different sections of the manual, e.g. Sections 3.2.2, 3.2.3, and 4.2, it
is emphasized that soil compaction or densification in the field should be
performed in order to obtain a soil blanket with low permeability. In the
case of soils with sensitive structures, the low permeability is achieved not
as much through densification a<; by a structural improvement of the soil.
This aspect of the problem raises serious doubts about the terms "densifi-
cation" or "compaction". Indeed, since the in-place soil is the material
which is improved in a soil liner, the improvement is done by "remolding and
recompacting" the soil.
To reproduce this procedure in laboratory condition, advantage has been taken
of available information regarding the effect of compactive effort and of
different compaction methods on soil structure and flow properties. Ac-
cordingly, a minimal test program should comprise both static and kneading
compaction procedures. The research should be concentrated on the "wet-of-op-
timum" which has greater flow-sensitivity implications for the soil. However,
the degree of sensitivity can be ascertained only when permeability tests are
conducted on soil samples which have been compacted at known combination of
density and moisture content. Thus, it becomes clear that the two aspects
(compaction and permeability) are related and compaction efficiency should be
investigated as a comprehensive test program.
To generate a moisture-density relationship, we recommend ASTM D698 and ASTM
D1561. Additional information can be obtained by comparing the results
obtained by ASTM 01557 with those obtained by the low-compacting effort
method, ASTM D698. When using the kneading .compaction method, ASTM D1561, it
is important to vary the thickness of the compacted layer and/or the amount of
compactive energy per layer.
5.2.2.3 Permeability to water
A clay soil's permeability (K) is a numerical value representing its ability
to transmit- fluid. From Darcy's law for liquid flux through a porous medium,
it can be seen t-hat a soil K value is independent of the volume of soil,
the volume of fluid passing, and the hydraulic gradient moving the water:
J = — =
A
where:
J = flux of a fluid (cm^cm'^s"1)
Q = flow (cm3 s"1)
K = permeability coefficient (cm
AH = hydraulic gradient
A = cross-sectional area of flow
210
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and since:
t
where:
V = volume of fluid (cnr)
t = time (s)
therefore:
K = ^-
AtAH .
Darcy's law assumes direct proportionality between the hydraulic gradient
(AH) and the flow rate (Q) where flow is laminar. Accordingly, any change in
the permeability coefficient (K) will represent a change in the porous media.
For comparison of a clay's permeability to different fluids, the fluid's
viscosity and density must be incorporated into Darcy's law along with the
gravitational constant. So adjusted, the permeability coefficient is changed
to the intrinsic permeability coefficient (IPC):
K1 = K ——
G
where:
K1 = IPC expressed in the c.g.s. system as cm2
K = permeability (cm s~^)
n1 = kinematic viscosity (cm2 s"^)
with
i n
n • —
n = viscosity (g cnT^ $'*•)
P = density (g cm"^)
G = gravitational constant, 981 cm s'2 at 45° latitude.
Viscosity normalizes a fluid's resistance to flow due to its cohesiveness,
while the fluid's density values normalize the effect of gravity on its flow.
Use of IPC values permits the addition of K' values where there is more than
one fluid flowing through a soil.
A representative sample of the spectrum of pure organic liquids often placed
in waste impoundments was investigated to determine their effects on the
211
-------
permeability of clay liners. Results of this study are reported in Chapter 4.
Central to these tests was the development of a constant pressure permeameter
suitable for permeability measurements of compacted clay liners subjected to
organic chemicals. The test apparatus and methods for the permeameter are
given in Appendix III-C.
Several factors not incorporated into these laboratory tests enter into a
clay's overall permeability. Sherard et al. (1963) listed the primary factors
determining "effective overall permeability" of a layer as: continuity,
regularity, thickness, and characteristics of interbedded layers or lenses. A
laboratory determination of permeability cannot take into account this type of
variability in a clay liner. It attempts to characterize only a homogenized
sample of the clay soil. Nevertheless at this point we must rely on labor-
atory tests.
5.2.2.4 Permeability to waste liquids
The previous subsection presented the permeability of water through a clay or
soil medium. This section is concerned with the permeability of soils to
waste fluids. This topic and related topics have been discussed in detail in
Subsections 2.2.5, 3.2.2, and 3.2.3, as well as Sections 4.2 and 4.3. These
sections stated that the interaction of clays and soils with various waste
fluids can be adverse, resulting in the loss of the structural and chemical
integrity of the liner. The range of waste fluids that have been tested is by
no means extensive or exhaustive. Much research work remains to be done
related to individual wastes not yet tested. Before finalization of design
and initiation of construction, compatibility testing of the expected wastes
to be contained with the proposed liner types should be conducted. As a
minimum some pilot or laboratory scale permeability testing with wastes should
be conducted. Presented in Appendix III-C is an experimental permeameter
which can be used for'accelerated testing.
5.2.2.5 Determination of soil strength characteristics
It is generally recognized that testing of a soil specimen in the laboratory
with the purpose of determining its strength characteristics should simulate
the failure possible to occur in the field. Of particular significance are
pore-water pressure changes and their relation to soil strength. If field
volume changes are prevented, pore-water pressures can develop- in the soil.
The simple situation in which the soil accepts water under a certain confine-
ment and then deforms in shear without change in volume, can be duplicated in
the laboratory in a consolidated-undrained triaxial compression test (CU-
test). For this purpose, ASTM 0 2850 should be used with the provision that
volume changes are permitted while the sample is under 0-3 loading (chamber
pressure).
Despite its tremendous advantages, triaxial testing has its limitations. One
of the important drawbacks is that in the apparatus the sample can reach
only a limited strain, sometimes considerably below the values of strains
required in slope stability analysis; this is particularly true with cohesive
soils. On the other hand, it may be more meaningful to perform an extension
rather than a compression test since this condition seems to reproduce slope
failure better.
212
-------
Apart from the triaxial technique, either a direct shear or a vane shear
apparatus can be used to determine soil strength characteristics. The most
important fact to be remembered is that the possible failure mechanism must be
reproducible in the laboratory.
The strength properties of clay soils are important not only with regard to
slope stability, but also with regard to the task of compacting the soil to a
particular desired density. It has been suggested that, in the case of
plastic soils, if the moisture-density relation is such that a California
Bearing Ratio (CBR) value lower than five is obtained, the roller will do a
poor compacting job since the soil will tend to "ball up" and the roller may
not "walk out" properly (Burmister, 1964).
In the design of a sloped soil liner, the first approach should be to compact
the soil using the parameters which are considered to generate the least
permeable soil, i.e. without consideration of strength properties. If, by
using this procedure, a critically weak soil is generated (safety factor less
than 1.2), then ways to improve strength properties should be investigated by
testing; the main task should be to ascertain the most economical way of
improving the strength of the soil liner associated with the least detriment
to soil permeability characteristics.
The exact conditions which have to be observed during the field compaction to
obtain the highest safety factor cannot be explicitly stated; Seed et al
(1960) wrote: "Since the influence of these factors are often conflicting -
for example, a flocculated structure promotes high strength at low strains but
it also promotes high expansion characteristics - a variety of patterns
relating undrained strength after soaking to initial composition can be
obtained for various types of soil."
The observations described in this section with regard to the effect of
varying compaction conditions upon strength should be considered only as
indicative of what may happen with any particular soil. In this discussion,
the emphasis is deliberately placed on the effect of soil structure on
strength; this is not to say that chances of encountering a structure-sens-
itive soil are very large. Probably, the reverse is true. The over-estima-
tion of structural effects in our discussion is made because:
a. Structural aspects are relatively more important in the group of
cohesive soils with a relatively high clay content.
b. In basic geotechnical literature, relatively little information is
found on the subject.
Since one of the basic requirements with regard to a soil to be used as a
liner is its relatively high clay content, and since such soils are called
"cohesive" because of the presence of cohesion when undisturbed, it should be
mentioned that most- of the normally consolidated remolded soils lack such a
cohesion (Seed et al, 1960). This., observation was made with the considera-
tion that any compaction operation is, to a certain degree, a remolding
operation.
213'
-------
As Mitchell (1964) stated, "Perhaps the single most important reason for
soil compaction is to increase the soil strength". It has been shown that CBR
strength of a silty clay is directly related to the density achieved over a
wide range of moisture contents. As has been shown (Mitchell, 1964), at water
contents over the optimum, the CBR strength was also affected by the water
content during compaction.
The strong dependence of the "as-compacted" CBR strength on density at mois-
ture contents below the optimum moisture is evidence of minimal structural
effects. In this range of moisture content, densification is not associated
with a considerable deflocculafion of the soil structure. Strength is a
strongly correlated function of density.
The opposite happens in the wet-side-of-optimum range where it is observed
that irrespective of the magnituce of the compactive effort, the strength is
the same at a particular moisture content (Burmister, 1964). Slightly higher
densities obtained with greater compactive efforts and an eventual increase in
strength effect are offset by a mere deflocculated (weaker) structure.
The method of compaction also has a very large effect on soil strength. Its
effect is manifested mostly on the wet-side-of optimum (Seed and Chan, 1959;
Seed et al., 1960). Whether a s:atic or a kneading compaction procedure is
used on the dry-side-of optimum, tne characteristic structure of the soil will
be the flocculated one and, at the same moisture content and density, the
strength will be unaffected by the method of compaction. In the high range
of moisture content, the kneading compaction is much more efficient in de-
flocculating the structure and, at the same density and moisture content, the
soil is considerably weaker than the soil compacted statically. Seed et al.
(1960) performed unconsolidated-undrained (UU) strength tests on a compacted
silty clay soil and found that the statically compacted samples were four
times as strong as those compacted by kneading. As Seed et al. made clear,
only the general trends of the observed behavior can be considered as being
valid; strength properties of soils can vary appreciably with regard to the
compactive effort and the method of_ compaction.
The observation revealed by the work performed at the University of Califor-
nia, Berkeley (Mitchell, 1956; Mitchell, 1964; Seed and Chan 1959; Seed et al,
1960), that the strength of the statically compacted soil is greater than the
strength of the soil compacted in a kneading device refers to values of shear
stresses recorded at relatively snail strains (5%). When values of shear
stresses corresponding to larger strains (20%) were considered, no differences
were found. The explanation advanced was that the prolonged shear in a
statically compacted sample generated a structure similar to the one charac-
teristic for the sample prepared by the kneading compaction procedure. This
raises an important practical problem: in assessing the"value of the shear
stress for a particular design purpose, consideration has to be given to the
range of meaningful strains. Since the strength determined is used to calcu-
late slope stability, a safe procedure would be to consider the "ultimate"
value of strength (Lambe and Whitman, 1979) or the "residual" one (Skempton,
1953), which means "shear stresses at large strains".
-------
It is known that, at the same void ratio, the strength of a flocculated soil
is larger than the strength of a dispersed one (Mitchell, 1956), which reite-
rates the fact that, in the case of many clay soils, the soil structure is
of paramount importance. Often, the effect is so large that, if samples of
the same soil subjected to different histories are brought to the same density
and moisture content via soaking and consolidation or swelling, the stress-
strain and strength properties will be still different because of the differ-
ence in the initially established structure (Mitchell, 1964). This structural
difference will generate different patterns of pore-water pressure development
with the result that, if the strength of these structurally different soils
were to be assessed in terms of effective stresses, no difference in strength
would be found between the two samples (Seed and Chan, 1959).
Pore-water pressure characteristics of a soil during shear are a reflection of
clay structure which depends on the chemical and mineralogical characteristics
of the clay. It has been proven that even a partial replacement of an
exchangeable cation can substantially alter the strength of clays (Mourn and
Rosenquist, 1961). Since the waste effluent differs in chemical composition
from the pore-water solution, cation exchange reactions can be anticipated
which can have a substantial effect on strength and permeability properties of
the soil.
While the strength of an "as-compacted" soil can be determined relatively
easily, the strength of the in-place soil liner is harder to determine.
Saturation, consolidation, or swell are some of the important changes which
can operate in the field with important repercussions on stress-strain and
strength properties (Seed et al , 1960). The relatively simplified situation
in which the soil soaks under a certain confining pressure and then is loaded
to cause deformation at constant volume is simulated in the laboratory by a
consolidated undrained (CD) test; this is the usual procedure for assessing
soil strength for pavement and earth dam designs. In this situation, the
strength will be dependent on structural characteristics and void ratio since
both determine pore-water pressure characteristics during shear. Samples of a
silty clay soil, prepared by kneading compaction at different densities and
moisture contents, if soaked with no change of volume, will be stronger with
lower compacting moisture content if the stress at 5% strain is considered; at
larger strains (20%), the strength is unaffected by the moisture content
during compaction (Seed et al , 1960).
Regarding the stress-strain relationship and the way it relates to composition
during compaction (density and moisture content), for structure-sensitive
soils, the more flocculated the structure, the larger the shear-modulus, the
stiffer the soil (Seed and Chan, 1959). In testing a silty clay soil in
consolidated undrained compression (33 = 2.0 kg cm"'), it was shown that the
lower the moisture content during compaction (the more flocculated the struc-
ture), the larger the deviator stress at any particular strain. Simultane-
ously, the pore-water pressure was higher with larger compaction moisture con-
tent so that the effective principal stress ratio or the effective obliquity
Index (a'i/a'3) was practically the same over a large range of moisture
contents during compaction. This again emphasizes the functional relationship
between chemical and mineralogical character!stics-structure-pore water
.pressure-strength (Mitchell, 1964, p. 89).
215
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5.2.3 Designing of Soil and Clay Liners
As a hydraulic structure, a clay soil liner is designed with the main purpose
of obtaining a blanket which will considerably impede the movement of the
liquids waste into the adjacent, undisturbed soil. The clay soil candidate
should be tested with the waste to determine the effect upon permeability.
Soil strength considerations will not be looked upon in this section because
of their secondary importance. If, for particular areas of the waste-disposal
site soil strength characteristics are relevant (for instance, in conjunction
with slope stability), the designer will recommend compaction procedures which
will yield the required strength without detrimentally affecting the imperm-
eabi1ity of the site.
Another facet of the design process for soil and clay liners is the provi-
sion for keeping adequate construction records and' documentaiton, as well as
retention of representative samples of field molded and compacted samples of
liners and subgrade. The above records and samples will allow for timely and
efficient verification of the construction and provide sufficient baseline
data to evaluate ongoing performance.
The temporary immobilization of some contaminants along the depth of the soil
liner is likewise not considerec in this section, being probably negligible
compared to the attenuation in the underlying soil often with a greater depth
than the soil liner. Disregarding the attenuation capacity of the soil
liner will produce an error on the safe side.
The starting point of the analysis for design should be the limiting seepage,
the permissible flux q-, between the soil liner and the underlying soil.
This level of tolerable flux will be obtained as a result of a careful
consideration of the following factors:
a. Waste-disposal site characteristics
- Size
- Shape and the angle between the long side of the waste disposal
site and the direction of groundwater flow.
b. Waste-effluent characteristics
- Number of pollutants at a dangerously high concentration
- The concentration (c) of the pollutant for which there is the
highest ratio c/d.w.s. (d.w.s. = drinking water standard)
c. The attenuation capacity of the underlying soil and its capacity to
render groundwater contamination less probable.
d. Groundwater characteristics '
- Depth
- Flow rate.
216
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e. The sink-source distance, i.e. the distance between the contamination
point (the waste-disposal site) and the usage point (the well deplet-
ing the aqui fer).
Once the q^ value (the seepage between the soil-liner and the underlying
soil) is obtained its value should be incorporated into the analysis to
generate the soil permeability K for the known geometry characteristics and
material properties of the system. A discussion of such an analysis is
provided in Appendix VI.
As it has been indicated in previous sections on testing procedures, three
main soil characteristics have to be investigated:
a. Soil compactibility
b. Soil flow properties
c. Soil chemical sensitivity.
Soil compactibi1ity is determined by performing the Proctor compaction test.
The results, the optimum moisture and particularly the maximum density, have
to be judged by the designing engineer using background information on text-
urally simi1ar soi1s.
Soil flow properties shall be determined on samples prepared using one of the
indicated ASTM procedures. The fluid to be used, at this stage, is either tap
water or 0.01 N CaS04 solution. The results of this test, coupled with the
Proctor compaction data, will reveal the ranges of soil moisture content
during compaction and soil densities where soil permeability drops below the
required soil permeability corresponding to the permissible flux q_. Com-
paring the two sets of data (soil compaction and soil permeability), the
designer will be faced with the following situations:
a. There is a broad range of moisture content (w) and of soil bulk
density (p) where the permeability (K) is less than the permissible
permeability (K_). Moreover, the two ranges practically overlap.
This is expressed in Figure 5-4 by a unique relationship between
p and K.
This situation is the safest possible and the design engineer should
not have any problems in optimizing the moisture of the soil during
compaction and the corresponding density. If, in the tentative
calculations, the depth of the soil liner De was on the high side
(around 5 feet), the findings of the two tests reveal a way of
reducing it. Such a reduction should not increase the flux q
between the soil liner and underlying soil to more than 0.8 qp.
b. There is a range of moisture content (w) over which K
-------
10
Z
LU
Q
Qfl
o
to
SOIL MOISTURE CONTENT, W
CQ
<
LU
2
-------
of this structure, the soil must be compacted at a lower moisture
content, a higher density, and a higher permeability. The designer
has to readjust the depth of the soil liner De (increase it), such
that the condition q = 0.8 qp is still observed. The condition
describing this situation is presented in Figure 5-5.
c. The required Kp value cannot be obtained. For this situation the
only alternative, if economically feasible, is to increase the depth
of the soil liner De and design for a larger K than originally
planned. The import of a better soil material or fundamentally
changing the type of lining, e.g. admixes, polymeric membranes, etc.
should be considered at this stage.
The preceding discussion has to be considered only as a recommended procedure
in using the test results for design. Often a more extensive research program
is needed before the optimum design criteria are reached. Furthermore, it is
to be expected that some recommendations generated at the end of the testing
program cannot be easily translated into field compaction criteria for the
preparation of the soil liner. The extrapolation of the test results for the
field condition has to.be done very carefully. The best approach is to
understand the field condition and the construction limitations and perform
the tests paralleling them as closely as possible, so that no extrapolation
wil1 be requi red.
5.2.4 Excavation and Embankment Construction
5.2.4.1 Excavation and sidewall
After planning and design stages are completed, construction activities
commence. In most instances, the "earthwork" is performed by a general
engineering/construction contractor. The types of equipment utilized vary
with the size and complexity of the job. 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 5-6, 5-7
and 5-8).
If surface water develops to a significant degree because groundwater is
encountered during excavation, potential detrimental effects on the success of
the subsequent liner installation may evolve. The presence of free standing
water in the excavation will not only hinder the work of heavy equipment, but
also will" severely hamper liner installation activities. Similarly, rainfall
can hinder excavation- activities, and, in some cases halt work by creating
adverse trafficability. If free water persists at the impoundment base, an
artificial base may have to be constructed. Generally, gravels of various
sizes are packed into the earth, then covered with sand or other available
material such that a stable, firm working surface for later grading is achiev-
ed. Costs are greatly increased by the need to build a water-free surface for
a liner installation in wetted areas.
219
-------
01
Z
LU
Q
00
O
00
SOIL MOISTURE CONTENT, W
03
<
uu
Q.
O
00
Kp
OPTIMUM MOISTURE
SOIL MOISTURE CONTENT, W
DRY-OF-OPTIMUM
03
<
LU
2
cc
LU
0.
O
to
WET-OF-OPTIMUM
MAXIMUM DENSITY,
O max.
SOIL BULK DENSITY, P
Figure 5-5.
Schematic representation of the relationships w-p , w-K and
p-K, for an idealized soil with no particle orientation when
compacted at high moisture content. (Case 2).
220
-------
.-_^-c:?
^^S^S^ti^^^' ; "%J '^^ ' '! • *:• :'-r r "
Figure 5-6.
Typical earthwork equipment used during impoundment construction,
dozer with blade (top) and dozer with compactor and blade (bot-
tom).
221
-------
Figure 5-7,
Trenching machine for anchor trenches (too)
mover for berm construction (bottom).
222
Dozer and earth
-------
Figure 5-8. Conveyor system used during impoundment construction.
During the excavation process, all vegetation (tree trunks and roots in
particular) should be removed from the site. Any depressions resulting from
stump removal or similar condition should be filled in with suitable backfill.
Slopes will be constructed by normal 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, even
on 3:1 slopes, additional arrangements may be needed to ensure that equipment
can travel safely up and down slope. A simple link to a large dozer, another
heavy piece of equipment, or a winch stationed at the top of the sidewal1/berm
can be utilized. The equipment at the top then helps to pull the working unit
up the slope, and helps to retard its downslope progress on the return trip.
When the side slope is steeper than 2:1 the "helping hand" approach is manda-
tory. 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 chain!inked "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 an example of
the type of equipment which might be used like this.
5.2.4.2 Drainage and leak.detection/control systems
An underdrain system may be necessary where there is a high groundwater table
or source of water infiltration. Underdrain systems may serve the purpose of
223
-------
transmitting fluids beneath and through the impoundment site without interac-
tion with any contaminants from the impoundment facility. Kays (1977) identi-
fies the following five parts in an underdrain system: (1) interceptor, (2)
collector, (3) filter, (4) conveyor, and (5) disposal mechanism (See also
Cedergren, 1967.)
The interceptor receives any liquids resulting from leakage or natural drain-
age. Interceptors should underlie the entire facility, including the side-
walls, if they are to be effective. Usually, the interceptor is composed of
the following three parts: (1) a base layer of low permeability, (2) an
overlying permeable lattice layer, composed of gravel, open graded asphalt or
some other suitable material, and (3) a covering layer to protect the over-
lying liner from penetration by the permeable lattice materials; fabric
materials (like geotextile filter blankets), graded earth, coarse sand, and
others are in use.
The function of the interceptor is to convey seeping fluids to the collector.
The collectors are generally located in blankets or trenches in the bottom of
the facility with the number of feeding collectors being dependent on the size
of the impoundment and the collector's basic design. Underdrain tile and
perforated pipe have been used for the collector system.
Filters are required where there is a danger of the lining material .fines
(clay soil lining) working into the interceptor material. Filters can be
constructed in the field of graded permeable soils, or may be one of the many
commercial filter media now available. The purpose of the filter is to stop
the migration of particles within the system. The movement of particles into
the conveyance and collector can, and will, eventually inhibit the acceptable
operation' of the underdrain system. Any sign of turbidity in liquid issuing
through the underdrain system could be a sign that the filtering system may be
failing. According to Kays (1977), "The filter is an item often neglected in
an underdrain complex. Its omission is responsible for triggering many mal-
functions. "
The underdrain monitoring system feeds into a closed pipe conveyance. The
conveyance system must be sized to handle more than the expected optimal
flows, as any backup within the system can cause serious repercussions (e.g.
instability of the embankment). Kays (1977) advised that the conveyances
terminate in sumps, channels, drains, or concrete exit structures.
The underdrain monitoring system should allow any leakage from the impoundment
to be detected and managed. Some facilities have pumping arrangements whereby
leakage and underflow are pumped and returned directly into the impoundment,
while others collect the seepage and dispose of it offsite.
A critical need for an adequate drainage system will exist if groundwater is
present immediately below the impoundment. A well designed underdrain system
will minimize or eliminate (1) reverse hydrostatic pressure and (2) removal of
soil from beneath the liner due to 'groundwa'ter flow. Reverse hydrostatic
pressure occurs when the groundwater level exceeds the operating water level
in the impoundment. This could occu", for example, during normal level fluc-
tuations in a drinking water reservoir. The groundwater reverse pressure
224
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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.
5.2.4.3 Monitoring wells
Facilites which store toxic/hazardous wastes will be required to monitor the
condition of ground and surface water adjacent to the impoundment. Frequent-
ly, observation wells are drilled using normal techniques, standpipes insert-
ed, and samples are taken and analyzed periodically. Most monitoring wells
are pipes into which a water sampler can be -lowered.
5.2.4.4 Field compaction of soil for construction of lined
waste disposal facilities
The compaction of soil is an essential step in the construction of all types
of liners, whether they be soils for a clay soil liner or for a subgrade on
which admix, flexible membrane, or spray-on liners will be installed. Since
the soil liner must have low permeability, emphasis in the compaction of soil
for use as a liner is placed on achieving as low permeability as feasible.
The requirement for strength is secondary, but it is needed for the embank-
ments and dikes. For the subgrade, compaction of soil is needed to improve
structural strength, uniformity of the subgrade, and smoothness. The subgrade
sidewail particularly needs improved strength for stability. In this subsec-
tion, field compaction of the soil, the equipment, and the field tests requir-
ed in the construction of lined waste disposal sites are described.
The applicability and requirements for the various pieces of compaction
equipment that can be used to achieve desired compaction is presented in Table
5-3 taken from Coates and Yu (1977), pp. 90 - 91. The adequacy, use and
efficiency of each piece of equipment varies with numerous factors including
the following: (a)- type, (b) weight and transmitted energy, (c) thickness of
layers, (d) placement water content, and (e) 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 rammer.s) and manual
tampers (or rammers) are used for fine finishing work both in the base and
sidewalls. (See Figure 5-9). Power tampers and manual tampers are a necessity
for backfill compaction of trenches or where penetrations of the base or
sidewalls occur, e.g. around pipes, infl ow/outflow/overf1ow structures and
specialized supporting structures.
Compaction equipment can be selected based upon weight and transmitted energy
requirements. For noncohesive materials, compaction can be adequately achiev-
ed with track type crawler tractor and/or haulage units as light pressure and
vibration is the most effective methodology. 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.
225
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•tali 5-.. COMPACTION EQUIPMENT 4NO
Eau ipment
type
Sheepsfoot
rol lers
roi lers
-ol lers
4 iQrat ing
oaseo i ate
tractor
tamper or
rammer
App 1 Icaoi 1 ) ty
for fine-gramed soils or
dirty coarse-grained
soil? with nore tnan 20*
passing 10 . 200 -ne-sn; not
s u i t ao l e for clean
coarse-gr j ined ',0 i 1 s ,
part icu I ar 1 y jppropr 'ate
for compact ioa jf "flper-
v iQus zone 'or earth 3am
or \ inings «nere longing
of lifts :s imoortant .
F -|p n
501 ! S «l th 4 - 3X PdSS ing
Cr>r *'ne-'jr lingo ,o i . 1 ;r
* e ' i 3 r j o e o , j ' - t /
cr oase :ours«» como-Kt'on
tn earth dams, not
S J ! 1 J D 1 - ' J r : ' i- j n
• e i ! - -jr 4ded s ana s or
s » J t y (•*! **f- sa^is
• i tn 'ess :nan ioouc ' J*
oais'ncj NO 300 «esn
-ith 4 - jl passing NO
230 *esn, 3 1 aced :nor-
3esi suited f'or :oarse-
^rjmea 501 1 s *i tn less
than 4 - 3* oassmq No.
200 'flesh, placed thor-
oughly -et .
f o r j i f f i c j 1 1 jccess,
trencn oackf 1 1 1 . suiuole
for t\ 1 inorganic soi 1 s .
Requirements for comC'action of 95 to '00 per cent Standard 'Doctor,
•naaimum density
^omoacted Masses or Dimensions and weight of equipment
lift coverages
thicxness,
' n ' c*n )
6 Soil type root Foot
( 15) contact contact
area, pressures,
'rt.2 fen-2) osi(MPa)
4-6 passe1. Pine-grained 5 - ]2 250 - 500
30 (32 - 77) (\7 . 34)
9 r i i n e c1 f-ne-gramea ; . M 200 - 400
501 '- soil *[ 30 (45-90i M 4 - 2 3)
6-5 passes
'or coarse- Coarse-grained 10 - 34 ISO - 250
3 r i i i « o ^ ' 1 , 64 . 90 ) M J . i . 7 )
SOI 1
Efficient compaction of *et sot's re-
lame soi 1 s at lower -no i sture contents .
! 25 J (041 - Q.55 ^Pi) for cean gr any 1 ar
:-:moaction. .ne-' 'oad '3.300 - 25.J30 'a
i - 3 4 - r) 50 - : ' s
used; ^oot contact pressure snould
oe "eguliteo io is to ivoM
shearing the soil on the third or
fourth pdSS.
:ompaction equipment is availaole;
::nesion!o$; i j i ' -, , irqs-size
]ff] "'j 1 1 t ng
-oMers ire ivai'iO'e 'he <• Jnge
K 1 - ?Q -:^s 3 9 - 173 *N)
jenerally jse- n the - jnge of '0
proof -oiling of suoqraoe or oase
:ourse
/lorjt'ng oads ^r plites ire
xji'-prooel'ed, single ;r in
15 - '5 ": '045-45/fl),
/ar'ous t/oes of /iorjt'ng-.jr"jm
equipment should 3e consioe-ed :or
"rjccor *eignt jp to 60,300 10.
*eignts JP to 250 1 b ! 1 M
-------
Figure 5-9. Typical compaction equipment,
227
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Layers of cohesionless 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 two-thirds of the specified layer thickness (Coates
and Yu, 1977).
Heavy sheepsfoot rollers, pneumatic rollers, and vibratory compactors are well
suited for cohesive materials. The control of water content is essential in
achievement of a high density with cohesive soils. When clay is the lining
material and rubber-tired equipment is utilized for compaction, the surface of
a given layer will be quite smooth after compaction. In certain instances
where seepage might occur along this smooth plane, scarifying of the compacted
layer to insure adhesion of the overlying layer will be necessary. Figure
5-10 shows a water vehicle used to add water to soil prior to compaction.
Figure 5-10. Water vehicle used to prepare the soil for compaction.
5.2.5 Quality Control in Preparation of a Clay Soil Li
ner
A soil blanket compacted to line a waste disposal impoundment should comply
with the requirements stated in the design specifications. Compliance is
monitored by an independent inspector both in terms of-procedure and perfor-
mance requirements, i.e., the inspector checks the observance of the con-
struction procedure called for by the design and he verifies that the designed
performance is achieved when a soil liner is prepared in the specified manner.
These two objectives are met in the course of' construction by visual inspec-
tion and by testing. At no time during the construction should visual inspec-
tion be the only form of quality control.
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Inspection of the contractor's activity via sampling and testing should be
established before construction begins. This sampling and testing program,
followed on a regular basis, should provide the owner of the facility with
a general picture of the quality of the construction work that is being
performed. In addition to this quality control program, the inspector should
visually inspect the constructed soil liner for areas which he suspects may
not be meeting the design specifications. In such cases, the inspector should
set up a specific testing program to determine the quality of those areas
expediently.
One aspect of the inspector's task is to assess the quality of the construc-
tion in terms of its potential performance as a soil liner. Because of his
continual presence in the field, the quality control inspector has the op-
portunity to spot unusual site conditions not detected during the precon-
struction investigation and thus not singled out by the design specifications.
In this situation, the design specifications may be found not to have be-en
detailed enough. For example, although constructed in accordance with the
specifications, the permeability of the soil could be found to be unusually
high. If such a situation occurs, the inspector should see that the new
information is immediately transmitted to both the designing and constructing
parties and that steps are taken to adjust the particular design specifica-
tions and the corresponding construction procedures in light of the new
information.
The procedural specifications which have to be observed by the contractor and
assessed by the quality control inspector can be grouped in three categories:
those which represent soil characteristics during compaction, those which are
characteristics of the compacting implements (e.g. roller characteristics),
and those which characterize the compaction operation itself. In the new few
paragraphs, we indentify these characteristics.
1. Soil Characteristics
a. Control of soil moisture content prior to and during the liner
preparation-(compaction).
The moisture content of the soil should be in the ±1% of the
designed w-value. Even if the density requirements are met at
a lower value of w, the required moisture content has to be
observed, because, for the purpose of generating a liner of low
permeability, the moisture content during compaction is an
essential factor, independent of its effect on density.
» . *
b. • Control of soil density.
The inspection team has to assess the compliance of the compac-
tion operation using the Field Density Test Procedure Designa-
tion E-24 (Bur. Rec., 1974) and the Rapid Compaction Control
Test Procedure Designation E-25 (Bur. Rec., 1974). For the
clayey and sllty soils, the minimum field density should be 95%
of the Proctor maximum density of the fraction smaller than
4.75 mm (#4 sieve).
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If the results of the density tests are only marginally accept-
able, the contractor should be asked to improve the compaction
operation. In this case, the inspector should determine if the
increase in density due to the undertaken improvement of soil
compaction is accomplished by a decrease in permeability; thus,
the inspector must assess the efficiency of the newly recom-
mended densification procedure. The uniformity of soil compac-
tion, both horizontally and vertically, should be verified and.
observed.
2. Roller characteristics
The contractor should observe the design specifications referring to:
a. Size, arrangement, and safety features of the drums.
b. Number, location, length, and cross-sectional area of the tamping
feet.
c. Weight of the loaded roller. (As a general rule, the weight should
be over 4,000 pounds per foot of length of drum.)
3. Characteristics of the Compaction Operation
/he design requirements should be rigorously followed with regards to the
following:
a. Number of passes.
b. Thickness of layers. (The first lift should always be compacted
with extreme care and it should not be more than 8" loose lift.)
Thickness of layers in relation to length of tamping feet. (Each
compacted lift should be less than 2/3 the length of the tamping
feet so that the roller can ride high over the compacted lift and
insure bonding of successive layers.)
The extent of sampling and testing for moisture content and soil density
cannot and should not be rigidly stated. This is because, in some circum-
stances, the compaction operation may increase the heterogeneity of a field
site, and in others decrease it. Let us consider, for instance, a hypotheti-
cal situation in which a limited area is isolated in the design specification
as being covered by a "uniform" soil, i.e. a soil unit which, prior to and
following the compaction, is considered "uniform" in terms of density, mois-
ture content, and flow characteristics. Assume further that this area is not
as uniform as it was originally thought and that 10% of it is covered by a
soil unit which reacted quite differently to the recommended compaction
procedure. As a consequence, there is a possibility that, following liner
preparation, the heterogeneity of relevant characteristics will be increased
in comparison to the uncompacted soil.
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When the soil is "uniform" to start with and when a unique compaction proce-
dure is followed in the field, the soil should become even more uniform
following compaction. Thus, for example, assume that 30 density determina-
tions were done to characterize a soil prior to compaction, that the average
value was determined to be 90 Ib/ft , and that the normally distributed values
around this average were spread between 86 and 94 Ib/ft3, with a standard
deviation equal to 1.95 Ib/ft3. Following compaction, the same hypothetical
area was again sampled and the average density value of the 30 determinations
was (as was designed) equal to 110 Ib/ft. The two extreme values were 108
and 112 Ib/ft3 with a standard deviation equal to only 0.95 Ib/ft3. This
indicates that 95% of the field was compacted at a density range between 108.1
and 111.9 Ib/ft3. Thus, theoretically 2.5% of the prepared soil liner was
compacted at densities smaller than 108.1 Ib/ft3 and 47.5% at densities
between 108.1 and the required value of 110 Ib/ft3. If, as we previously
indicated, this designed value represents 95% of the maximum Proctor density,
the value of 108.1 lbs/ft3 corresponds to 93.4% of the maximum Proctor, i.e.
2.5% of the soil will be compacted at densities lower than 93.4% of this
maximum. Tentatively, we estimate that this value is an acceptable one and
any value of 90-92% of the maximum for at most 2.5% of the soil should be
considered as reflecting a uniformly dense soil liner.
The significance of the results of moisture content and soil density deter-
minations is questionable in relation to quality control, however, if these
results are not related to the density/permeability relationship. Knowledge
of this relationship will allow the designer to perform simple calculations
such as those presented in the previous paragraphs, and to assess how much
undercompaction can be tolerated safely. Briefly, if a soil's permeability is
not significantly higher at 90% of the maximum Proctor in comparison to its
permeability at 95%, a relatively large spread of density values can be
considered acceptable. In this case, if 2.5% of the soil is compacted at
densities less than 90% of maximum, undercompaction is an admissible alterna-
tive. However, if the permeability increases drastically when the soil is
undercompacted, the required standard deviation of the density values should
be minimal, i.e. 2.5% compacted* to less than 93-94% of maximum Proctor is not
acceptable.
The most significant requirement for a soil 1 i.ner underlying a waste disposal
site is its low permeability. To assess the permeability, the inspector
should perform both laboratory testing and field trials. The inspector should
verify that the K-value is within the required range, and he should also
correlate the permeability with the density-moisture content function, thus
verifying the relationships obtained during the pre-construotion investiga-
tion, upon which the whole design is based. If, over a certain limited area,
the relationships seem to be different from those obtained in the preliminary
investigation, the designing group should be informed immediately and asked to
assess the magnitude of the effect in terms of additional discharge below the
liner. If this additional flux is judged to be unacceptable, new requirements
should be given to the constructing group. The inspector should then assess
the efficiency of the revised compaction procedures as observed by the con-
tractor.
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As we already indicated above, the sampling and testing procedures in the
quality control program should be established before construction begins so
that they are available to the inspecting unit. To give an example of the
extent of an "adequate" quality control program, given the construction of a
hypothetical soil liner, three feet in depth, that is to cover an area equal
to 100 acres, the following number of samples may be required:
a. For determining the moisture content prior to compaction, and the
density obtained following the compaction, one soil sample for every
2,000 cubic yards of compacted soil liner.
b. For determining the laboratory saturated hydraulic conductivity, one
soil sample for every 16,000 cubic yards of compacted soil liner.
c. For monitoring the field infiIterability, one determination for
every 40,000 cubic yards of compacted soil liner.
These densities for sampling and testing will result (for the hypothetical
waste disposal facility) in determining the moisture content and density of
242 samples, in performing 30 laboratory permeability determinations, and in
performing 12 infiltration tests in the field.
The above example should only serve to give a very general idea of adequate
densities for sampling and testing. For instance, a liner designed at a depth
of 24 inches or less should be sampled and tested at a higher density. In a
real situation, local conditions may dictate a degree of bias in comparison
with the present example. Some of the circumstances which will allow the
inspection team to use a different sampling procedure are likely to be the
f o 11 owi ng:
a. The soil cover has an unusually low or unusually high degree of
homogeneity.
b. The degree of detail and accuracy of the preconstruction investiga-
tion is unusually low or unusually high.
c. The soil to be compacted is unusually homogeneous and or unusually
heterogeneous 'in terms of its initial moisture content.
The duration of the construction period and the extent of precipitation
during the course of construction should also be considered. The magnitude of
the area to be lined should not be a factor in establishing the density of
testing. Every unit area of the waste disposal site should be controlled with
the same care, regardless of the size of the site to be lined.
Apart from the general program' of sampling and testing related to a unit
volume of compacted earth, there should be occasional samplings, particularly
in the first stages of the construction" operation and often as a result of
visual observation. These samplings will mostly likely be prompted by the
following conditions: ., ..,,...
a. A systematic increase in the thickness of a lift over the specified
value..
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b. A moisture content of the uncompacted soil out of the specified
range.
c. A reduction in the required number of passes.
d. A "different behavior" under the roller of a particular area.
Sometimes, specifications may require the construction of a test area on the
site prior to the construction of the liner itself. If this is the case, and
if the outcome of compaction and moisture control are satisfactory, most of
the testing during the construction of the liner may be limited to that of
samples collected per unit volume of compacted soil liner. Density and
permeability tests in such a construction test area would provide valuable
information for use in determining the quality control strategy.
Often, a laboratory will need to be organized as close as possible to the
future waste disposal site. The particular type of facility needed depends on
the amount of earthwork involved (i.e. the number of samples to be tested),
the types of tests to be performed, the expected testing load per unit time,
the duration of the operation, etc. Detailed information on this subject can
be found in the Earth Manual (Bureau of Reclamation, 1974).
A detailed report on the control work performed should be maintained daily.
These reports are useful in tracing whatever work was not performed according
to the speci fications.
In the last 25 years, several radiation techniques have been developed for
determining both moisture content and soil density. However, only in the last
decade has substantial progress been made in the use of neutron thermalization
techniques for determining moisture content or in gamma rays and neutron
attenuation for determining both moisture content and' soil density.
The radiation methods are potentially useful for work performed during the
quality control activity. Some of the quoted advantages of these techniques
are their nondestructive nature, their ability to sample a relatively large
specimen, and their ability to be performed quickly. Among the disadvantages
are the fact that a careful calibration is required prior to testing for every
soil unit and that only a limited resolution is obtainable (i.e. soil discon-
tinuities are not sharply detected). However, these procedures have to be
better adapted for use in relation to liner construction.
The laboratory saturated permeability should be determined using Designation
E-13 (Bureau of Reclamation, 1974; ASTM D-2434-68, 1974), or "a falling head
technique (Black, 1965).
A field procedure for the determination of soils infilterability that can be
confidently applied in the case of soil liners is not really available.
However, the ASTM D-3385-75 or Designation E-19 in the Earth Manual can be
used. It should be indicated that, particularly with regard to the field
determination of water transmission characteristics of a soil liner, the
available methods should be improved and new procedures developed for measur-
ing waste transmission.
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5.3 Construction of Linings of Admixed Materials
5.3.1 Introduction
Admixes refer to a variety of formed-in-place materials such as soil cement,'
concrete, asphalt concrete, and bentonites. The characteristics of these are
described in Chapter 3, Section 3.3. The field construction of these lining
materials is discussed in the following subsections.
5.3.2 Soil Cement
Soil cement liners can be made from standard or plastic soil cement mixes.
The latter contains more cement and water than the former. Best results are
obtained when the cement is mixed with a well graded sandy soil (maximum size
3/4 in) as the cement is the minor ingredient. Type V sul fate-resistant
cement is recommended when the soil contains sulfate as determined by labor-
atory tests. The design mix should be tested by the moisture-density rela-
tions test ASTM 0558, wet-dry test: ASTM 0559, freeze-thaw test ASTM D560, and
the permeability tests of E-13 in the Bureau of Reclamation Earth Manual.
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 5-11. The surface of a compacted layer must 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. The
sealing compounds are bituminous liquids and emulsions sprayed onto the soil
cement surface after it has been sprayed with water to reach its maximum water
absorption level. This spraying should be done as soon after compaction as
practical (Day, 1970).
5.3.3 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 fron 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 concre~e. This will help prevent the
liner from drying too quickly (Bureau of Reclamation, 1963).
Concrete mixes for pond liners should be plastic enough to consolidate well
but stiff enough not to slip on side slopes. A concrete mix with a slump of 2
to 2.5 inches is usually satisfactory. It is important to control .carefully.
the workability and consistency of the concrete; a change of one inch in slump
will interfere with the quality and progress of the work. The maximum recom-
mended size of aggregate is 3/4 inch or less for a liner 2-1/2 inches thick.
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Placing machine is custom built to handle 10,000 cu yd of soil-cement a day.
Conveyor boom extends 100-tt to dump soil-cemeot mix tnat is
compacted by rollers in stepped lifts of 9-in.
Figure 5-11.
Steps in the installation of a soil-cement liner (Brown and
Root, Inc., 1978).
235
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The inclusion of air entraining agents is strongly recommended in areas where
the liner will be exposed to freezing temperatures (Bureau of Reclamation,
1975).
The actual placing of the concrete may be done by slip form or the use of a
screed. Finishing of liners is riot necessary since it is of little useful
value in this type of situation. Curing is important. The use of accepted
sealing compounds is recommended to produce satisfactory results.
Shotcrete or gunite is cement mixed with sand of maximum size of 3/16 inches,
although 3/4 inch 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).
5.3.4 Asphalt Concrete
Asphalt concrete for hydraulic structures such as a pond or landfill is
similar to paving asphalt- concrete but contains higher percentages of mineral
filler and asphalt. 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, MS-12, 1976).
The subgrade should be smoothed by rollers after compacting the top six
inches 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 feet wide, free from grooves, depres-
sions, holes, etc. Ironing screeds used with strike offs and screeds on the
spreader should be heated to at least 250°F before starting operations to
prevent sticking or tearing of the surface. Placing should be planned to
minimize the number of cold joints. Figure 5-12 shows the placing of a
two-inch thick asphalt concrete liner with road paving equipment.
The edges of spreads should be smooth and sloped for 6 to 12 inches to provide
a bonding surface with the adjacent spread. Cold sufaces should be heated
with an infra-red heater just before forming joints. Asphalt concrete mix-
tures 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 Institute, MS-12, 1976). The asphalt concrete liner should be
compacted as soon after spreading as possible. Ironing screeds, rollers,
vibrators or tampers may be used for compaction (Day, 1970). In order to
achieve a permeability coefficient of less than 1 x 10~' cm s , a voids
content of 4% or less is required (Asphalt. .Institute, MS-12, 1976). When a
liner thickness greater than 3 inches is required, multiple courses should be
applied. All joints should be staggered to insure strength and low permeabil-
ity for the liner as a whole (Day, 1970, pp. 56-59).
236
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Figure 5-12.
A two-inch thick asphalt concrete liner is applied using road
paving equipment and methods. After the surface cools, a seal
coat is applied (Shultz, 1982).
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5.3.5 Construction of Bentonite-Clay Liners
Several methods are available for the preparation of a lining based upon fine
grain commercially processed bentonite. Such a bentonite can be used as a 1
to 2 inch thick membrane covered with 8 to 12 inches of earth or gravel (to
protect the clay liner from erosion or mechanical damage) or it may be mixed
in with the soil to form a uniforn surface layer. The application rate for
the latter is about one lb/ft2 of soil. Similarly bentonite may be mixed
with sand, in a volume ratio of approximately 1 to 8 (3 lb/ft2 bentonite),
spread in a layer 2 to 4 inches thick and covered. Bulk spreading and mixing
of bentonite into a soil which has an unacceptable permeability is shown in
Figures 5-13 and 5-13a. After thorough mixing, the resultant mixture is
wetted and compacted (Schultz, 1982).
A slurry of bentonite (bentonite 0.5% by weight) may be added to existing
(filled) ponds to decrease the permeability of the soil or gravel liner. The
bentonite settles filling void spaces and effectively sealing the surface.
Bentonites vary in quality. The moisture content of the clay should be less
than 20% especially for thin membranes. Wyoming-type bentonite which is finer
than No. 30 sieve or well graded if coarser particles are present have proven
very satisfactory (Middlebrooks et al., 1978).
For some uses, e.g. canals, bentonite slurry can only be a temporary seal. It
is subject to shrinkage, cracking, and erosion from moving water. Also, any
calcium in the water will cause an exchange with the sodium on the bentonite
and an increase in permeability (Bureau of Reclamation, 1963).
5.4 Design and Construction of Flexible Membrane L''ner Installations
5.4.1 Introduction
The purpose of this section is to discuss the factors pertaining to the design
of systems for waste disposal facilities and to describe the methods and
equipment used to line the waste disposal facilities with flexible membrane
liner materials. Shultz and Miklas (1980) conducted a study to identify
current methods and equipment used to (1) prepare subgrades for liners, and
(2) place liners, particularly membrane liners. Much of the contents of this
section and Appendix IV is based upon the results and observations of that
project.
Flexible liner installations generally have similar planning, design and
construction components. One of the most important components and one which
is common to all flexible liner systems, is the subgrade, which serves as
the supporting structure for these liners. The quality and integrity of
the subgrade must be assured if the liner is to perform satisfactorily.
Inadequate subgrade support accounts for many of the failures of liner instal-
lations.
'Equally critical to a good project is the proper installation of the selected
liner material over the subgrade. Installation involves numerous steps and
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-TK~A^
. • -*r._ BS*-
•>£-'
Fiaure 5-13 Bulk application of bentonite with an oil field bottle truck
Figure 5-13. ^J^ fl s1x.foot wide distributor attached to the rear of
the truck. An outrigger on the side of the truck^allowed tne
operator immediate and safe~access to the material control
valves.
239
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Figure 5-13a. Mixing the bentonits; into the soil with a large agricultural
disc. Eight passes on a crisscross pattern are made to mix in
the bentonite. A large rototiller is also found to be useful
in blending in the bentonite. Water is added to the soil-
bentonite mixture which is then compacted.
planning before the job is begun. There -are many experienced installers of
liners presently operating in the United States. A partial list of installers
is presented in Appendix II. These companies have personnel trained in proper
field placement and seaming techniques which have been acquired through
installation experience and contact; with the liner fabricators and manufac-
turers. Such experience is needed by the owner of a facility and assures
adequate compliance with project plans and specifications to produce an
installation that will perform its intended function.
Each of these aspects is discussed in the following sections. Pictures,
figures and tables are presented to illustrate or support the discussion of
each major aspect. It is important to note that the size of lined impound-
ments can vary from less than one acre to many hundred. Because of the time
and cost considerations, several, if not all, of the constructions steps
discussed in this section may take place at the same time. For example, liner
placement may be in at one end of the impoundment while the. subgrade prepara-
tion at the other end of the impoundnent continues. Landfills may be lined in
modules or phases, making sure the lining.is adequately protected during the
time between lining installation and waste placement,
5.4.2 Planning and Design Considerations for Membrane Liners
Overall design and planning considerations for lining waste disposal facil-
ities are presented and .discussed in Section 5.1." In this section considera-
tions which pertain specifically to flexible membrane liners are discussed in
greater detail.
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5.4.2.1 Type and texture of "in situ" soils
In the planning/site selection process, care should be taken to select the
best available location for the proposed facility. The classification, rela-
tive homogeneity, and relevant physical, mechanical, and chemical character of
the "in situ" soils should be determined. Consideration should be given to
having the soils tested for Atterberg limits and grain size relative to
"shrink/swell" moisture, density, strength, settlement, permeability, organic
material content, clay mineralogy, ion exchange capacity, and solubility.
Appropriate soils engineering test methods should be used.
Soils which have high "shrink/swell" characteristics should generally be
avoided. The normal changes in soils which experience clay expansion (wet) and
contraction (dry) may act to weaken an earthen structure, both at the bottom
and on the sidewalIs/berm structures, if the clay is allowed to be alternately
wet and dry. Unwanted voids may be generated by repeated "shrink/ swell"
cycles, introducing water into the structure, thus encouraging failure.
The presence of organic material in a sovl below a membrane liner can cause a
variety of problems. Organic material can generate gases through natural
decay processes, and 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. The phenomena
of membrane liner displacement by gases produces the undesired "whale back"
effect where large portions of liner rise up and out of the liquid to be
contained (like a balloon), eventually rupturing or requiring rupture to
release the trapped gases. The decay of organic material can also create voids
which lead to base material slumping, subsequent liner shifting and potential
1 i ner failure.
The soluble material in the foundation material beneath a liner can also
cause both the gas and void 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
might also cause cavities and loss of liner support.
Removal of organic material and the installation of gas vents would be neces-
sary if the soil contains organic material, or if other gas problems are
known. The bottom of the impoundment must be sloped upward 2-4% minimum to
allow gas to reach gas vents.
5.4.2.2 Subgrade characteristics
The liner subgrade must provide a relatively firm and unyielding support for
the liner material. In this sense, the subgrade includes all excavated soil,
all engineered fill and all trench backfill. The performance of the subgrade
is dependent upon: (1) the loading it is subjected to by the weight of waste
applied; (2) the subgrade characteristics and subsequent groundwater changes;
(3) slope instability; (4) liner malfunctions; or (5) seismic activity. The
main characteristics or-relevance for subgrade materials are settlement
(stress-strain relationship), consolidation (strain-time relationship),
strength, and acid solubility. These parameters are readily determinable by
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field and laboratory tests. Simpler, less expensive tests which have been
previously correlated with these tests are performed during construction to
allow a thorough coverage of the subgrade quality. These simpler tests include
Atterberg limits, grain size, and compaction tests. Strength and occasionally
consolidation tests may be run on the subgrade earthwork, if deemed necessary
by the quality control programs.
5.4.2.3 Desired characteristics of bottom
and side surfaces
In most liner installations, the more plane and regular the subgrade side
slopes and base are, the easier and more reliable will be the liner instal-
lation. The largest particles in the subgrade soil on which the liner is to
be placed should be less than three-quarters inch with the fine finished
subgrade surface having only smooth rounded particles less than one quarter
inch in diameter exposed. Large gravel, cobbles, and boulders are to be
avoided. Furthermore, the largest particles should be rounded to subrounded
rather than angular. Where large particles are present, plan on either
removing them by hand raking or grading at least 3 inches to 6 inches below
the desired bottom elevation, and sjbsequently backfill with material with the
desired particle size characteristics, compacting the added material to
provide the desired homogeneous base and sides which are free from large
particles. In case where subgrade roughness cannot be avoided, a suitable
geotextile underlay, e.g. filter fabric, should be considered.
5.4.2.4 Location of bedrock
Carefully consider the alternatives to construction of a lined impoundment
when rock removal (through blasting and other procedures) and rock shaping is
required. The economic consideration will probably be paramount here, as the
cost of working in. rock is many times larger than construction activity in
weathered rock or loose material. In addition, the potential for large angular
particles and irregular surfaces is much greater. It may be desirable under
such circumstance to construct a "filled impoundment (see Section 5.1.1).
5.4.2.5 Stability of materials
The importance of utilizing a material with stable characteristics under
differing loading and climatic/meteorologic conditions cannot be overemphasiz-
ed. The reaction of a given soil to changes in stress or moisture content
should be considered in the design of a given structure. The selection of side
slope angles will also be governed by the ability of a selected material to
maintain the selected grades. Generally, a 3:1 or less slope is safe for most
materials, although seismic considerations may require flatter slopes. Wave
erosion may cause sloughing of the cover soil within the operating liquid
level and freeboard zone. This zone should be provided with erosion protec-
tion. Experience with earth dam design has provided us with a good source of
practical design solutions for this problem (Bureau of Reclamation, 1973).
5.4.2.6 Drainage consideration •- -
Surface runoff will be affected by the impoundment. If the impoundment is
the pathway of natural drainage, the diversion drainage systems, overfl
in
ow
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structures and later subterranean diversion systems .mist be planned to hand
the water excesses in order to minimize potential damage to the impoundmei
structure and minimize other adverse impacts. An underdrain system may t
required to remove groundwater which accumulates beneath the installed 1 i n«
through time. Infiltrating water beneath liners/impoundments is particularl
common in areas with high subsurface flow, or high groundwater table; tf
problem must be recognized in advance so that design accommodations can fc
made if the integrity of the impoundment/liner is to be maintained throughou
its projected life. Areas subject to flooding and areas with high water table
must receive special design, construction, operations and maintenance concern
5.4.2.7 Impoundment dimensions
The most economical shape for an impoundment is rectangular with straighl
sides. Curved sides and irregular shapes usually add to the grading anc
installation costs and increase the number of structural failure points that
can occur. Avoid circular impoundments as the grading costs and installation
costs for liner materials will be increased significantly along with the
construction costs.
5.4.2.8 Wind direction and velocity
Design of the pond must take into consideration the prevailing winds. «'i nds
adversely affect the liner in two principal ways, in t~e form of wave action
as the wind impinges on the liner and in the form of lifting action on the
slopes in the case of membrane liners. Proper venting of the membrane liner
at the top of the slope can mitigate or negate the airfoil effect created by
the slope. The placement of weight tubes on the slopes also helps to-break up
the flow of air across the pond in addition to providing ballast to hold the
liner on the slope (Small, 1980).
5.4.2.9 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 resitance to cracking may not be able to withstand the effects of
high tempertures. Low temperatures along with strong winds can result in a
flex fatigue type failure. Materials that creep at high temperatures may
elongate to failure during cycles of high temperature (Small, 1980).
Low temperatures which can cause icing or freezing introduce another set of
adverse factors to the structural integrity of the liner. Because of freeze-
thaw cycling, the integrity of the subgrade may also be affected.
5.4.2.10 Local vegetation
In addition to gas problems, vegetation can jeopardize liner integrity as a
result of growth. Certain grasses can penetrate flexible membrane liners.
Use of thicker sheeting may reduce such damage. Where certain woody vege-
tation or grasses are evident, soil sterilization with an appropriate her-
bicide may be required to prevent damage to the liner. Salt grass, nut
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grass, and quackgrass are examples of local vegetation which mandate soil
sterilization. The topsoil layer containing this vegetation should be removed
as a part of subgrade preparation. If these grasses are present, soil steri^
ization should also be automatically included in the construction process. 41
a soil sterilant is used, polymeric liners should not be placed immediately
after application. Time should 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.
5.4.2.11 Floor consideration
The floor of the impoundment should not be flat if there is the possibility of
gas production beneath the liner. The floor should be designed to slope
upward with a minumum grade of 2% from a low point near the center in order to
encourage gas movement out from beneath the liner. Since the vent design must
provide a permeable material to relieve the gas to the atmosphere, it may also
serve as a subdrain. The designer should provide for liquid gathering and
release as well as for safe discharge of the vent gases. If the liner is
being installed in a landfill in order to capture leachate, a leachate
collection system may be required in order to manage the leachate as it forms
and to allow the removal of quantities of infiltration water wmcn may enter
the landfill after periods of precipitation or snowmelt. Outside grades
should be designed to prevent an influx of runoff water into the pond.
Cut-off trenches should be used in mountainous areas to prevent washouts.
5.4.2.12 Berm width requirements
The width of the containment embankments will be determined by their height
and the design side slope; the width of the berm is an optional design factor.
The minimum suggested too width is ten feet in or^er to allow sufficient room
for equipmen-t and men to operate during liner, installation, to provide room
such that anchor trenches can be efficiently installed should they be requir-
ed, and to facilitate maintenance and repairs throughout facility life.
5.4.2.13 Inflow/outflow/overflow conveyances
The fewer penetrations in a lined impoundment, the greater its probable
integrity; thus, if possible, inflow/outflow piping should be designed to go
"over the top". If inflow/outflow piping is required, select pipes made of
materials which are compatible with the liner type. During installation, soil
around the pipes should be well compacted to insure that voids and loose
structures are eliminated. If an "over the top" inflow pipe is used, a splash
pad may be needed to prevent system damage to the liner.
5.4.2.14 Monitoring and leak detection systems
If monitoring wells are needed, locate them both up gradient and down gradi-
ent of the impoundment so that the back-ground quality can be compared with the
possibly contaminated groundwater. The down gradient monitoring wells should
be designed to monitor groundwater before the groundwater leaves the site
facility boundary or emerges into a surface water body. The number of wells is
dependent on the size of impoundment, the material stored, the relative need
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for early discovery of leaking material, and tne environmental sensitivity o
the local system (EPA, 1977).
Some hazardous substances to be stored in lined impoundments are potential 1.
so damaging that the regulatory agency may require a leak detection system t>
installed immediately beneath the impoundment. The system will usually involvi
two liners; an underliner of clay or other suitable material will be overlaii
with one to three feet of permeable material. The underliner will slope towan
a center low spot either at a point or along a trench which extends the lengtt
of the impoundment. A suitable liner material will be placed over the perm-
eable material. If the primary (uppermost) liner leaks, the leaking material
will be channelled to a collection point either via the trough or in the
centralized low point. The leaking material will be collected, removed, and
discarded either back into the reservoir or by other acceptable means.
Such a procedure as described above can indicate whether there is one or more
leaks in a landfill or an impoundment, but gives no indication as to the
location of the leak or leaks. It is highly desirable to know the locations
of all leaks. For example, the time delay between the start of a leak and the
pollutant entering the monitoring system can be lengthy. Also, if repairs can
be made, the location must be known. To fill this need, EPA has undertaken
research projects to in-vestigate the feasibility of locating leaks and of
•developing leak detection techniques which can be applied to landfills. The
initial study has indicated that developing such methods is feasible (Earth-
Tech, 1982). Two contracts, 63-03-3030 and 68-03-3033, are ongoing to
develop techniques for detecting leaks in old landfills and designs for leak
detection systems which can be incorporated in new disposal facilities.
5.4.2.15 Monitoring liner performance
An important output of the planning and design process is a procedure to
monitor the performance of the installed liner. The procedure should be
relatively simple to perform and produce verifiaole results (probably through
coupon testing and evaluation and periodic grouncwater monitoring). Ideally,
the monitoring of liner performance should be :n situ, nondestructive, and
nondisruptive. Realistically, performance monitoring will most likely involve
sampling of soils and waters from selected locations beneath the liner and/or
the subgrade. This topic is highly site specific, and as such the factors and
procedures differ for each facility.
The setting up of a "coupon" testing program is suggested in which samples of
membrane from the same lot as the emplaced liner are placed in the waste at
the start of operation of the impoundment and withdrawn and tested on a
planned schedule. Such a procedure can be used for monitoring the condition
of the actual liner during its exposure to the waste. The planning and design
process must detail the coupon program. A more comprehensive treatment of
this subject is presented in subsection 5.4.7.
5.4.3 Preparation of Subgrade for Flexible Membrane Liners
5.4.3.1 Compaction of subgrade
Compaction of the subgrade soil is required'to provide a firm and unyielding
base for most lining materials, be they admix, synthetic membrane, soil, or
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other. Generally, a fill subgrade is built up in a series of compactec
layers, whereas an excavated subgrade is compacted only at its surface.
Usually, the minimum compaction of the subgrade material will be specified.
Most liner installations require the density of the subgrade achieve at lea^
a specified percentage of that obtainable by the Standard Proctor Test, A^Q|
0698, with 90% of Proctor being the most specified relative compaction. Some
contracts will specify the compaction equipment which is to be utilized,
number of equipment coverages per layer, layer thickness, permissible water
content range at placement,and method and location of water addition.
The regularity and texture of the surface of the uppermost layer in the
compaction scheme is critical in the liner installation process. A plane
surface after compaction is the most desirable one for liner placement but is
not always achievable or specified in the contract. In many installations,
soil clods or local surface irregularities will be flattened (further compact-
ed) by the overlying weight of the stored material after the impoundment is
filled. Further, it is thought that the flexible membrane liners will adjust
their shape over any clods so that no detrimental effects will result.
Nevertheless, rocks or irregularities with sharp edges should be eliminated
from the finished subgrade during the compaction/ construction process even
when not specified in the contract if a thin flexible liner integrity is to be
maintained.
Within the flexible iiner industry, there is a difference of opinion as to how
smooth-surfaces iiust be to insure liner integrity. The opinions vary with the
liner material. All installers would agree, however, that the smoother the
finished surface, the easier the task of flexible liner installation.
5.4.3.2 Fine finishing of surface
After compaction has been completed, it is normal to fine finish the surface.
Fine finishing is an intensive ?spect of subgrace preparation. Depending.on
the design specifications, var.jus techniques are used. Often, teams of men
(generally from two to ten 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. Men are also encouraged to tamp down any soil which can be
manually disaggregated and spread.
The desirability of a smooth surface on the bottom and sidewalls has given
impetus to the utilization of various drags to aid in the formation of a
regular, flat working surface. Usually, the fine finishing with vibrating
rollers and drags will need to be accomplished on a slightly wet surface;
thus, water tank trucks are a familiar sight during the fine finishing
activities. Fine finishing with a smooth steel roller is sometimes required.
Occasionally, soil additions are required to bridge surface irregularities if
the irregularities cannot otherwise be removed. Sand is useful for this
purpose as it is easily compacted.
Figure 5-14 shows examples of subgrade that require additional work before a
membrane liner can be placed. Figure 5-15 shows scraper and roller being used
to fine finish a subgrade. Figure 5-16 presents examples of suitable subgrade
texture prior to placement of a flexible liner.
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Figure 5-14.
Photographs showing various stages of subgrade finishing
subgrades require further work.
, 247
These
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— •*-. 3e^- -*•—'••'«
"9--.5.,5. ScrWr.ndr8l,erbein9use<|tof1ne
to
of a
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The control of unwanted grasses and otner types of vegetation is accomolisnea
in the fine finishing stage through removal of the layer containing the
vegetation and/or the application of a herbicide to the finished slopes and
base. The selection of a proper herbicide is critical as some species found in
western states are not killed by certain herbicides commonly used in the more
humid eastern United States. All fill obtained off-site should be inspected
well to ensure that both germinating and inactive seeds and roots are killed
by the application of herbicide.
Generally, it is advisable to wait a few days before laying liner material.
"Figure 5-17 shows what can happen if a herbicide is not applied properly. The
picture shows salt grass penetrating a 30 mi 1 membrane liner. When applying
herbicides, proper protection against inhalation and ski.n contact should be
taken.
v, '. \^J . . "\
• / *q *, v
V \ *
Figure 5-17.
Salt grass penetrating a 30 mil flexible liner.
ization is important prior to placing a liner.
Soil steril-
The activities of excavation, construction, trenching, compaction, fine
finishing, and liner installation are generally all progressing at the same
time on larger jobs. It is desirable during dry weather to apply water or
other dust control compounds since the field seaming process is best completed
in a dust-free environment.
The fine finishing process is critically dependent on the proper care and
control of water. If rain occurs during or immediately after the fine finish-
ing work on a slope, rills, ruts, ravines, etc. may be eroded into the sur-
face. Thus, the expenditure of effort to fine, finish slopes and bottom for
subsequent membrane liner placement should be curtailed when rainfall is
imminent; conversely, the placement of liner material on fine finished slopes
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should be as soon after completion of "finishing" as possible to ensure that
no surfaces are "lost" to the erosive effects of surface runoff.
5.4.4 Liner Placement ^
The installation'of flexible membrane liners requires a significant planning
effort prior to construction. This planning effort must include consideration
of the storage and security of all necessary equipment, installation equip-
ment, manpower requirements, the placement operation, field seaming, anchoring
and sealing, quality control, inspection, and protection of placed liners.
All of these considerations are discussed in detail in Appendix IV.
5.4.5 Quality Control in Construction of Liner System
A comprehensive quality control program during design and construction is
a vital element in the planning, design, and construction, and operation.
This program is necessary to assure that the materials used will meet facility
requirements and demands, and tnat workmanship conforms to the installation
specifications. A quality contrcl program will provide the operator and owner
with confidence that the facility was constructed as olanned and will function
as intended.
As a minimum, the following items should be considered for incorporation into
a quality control program:
- A checklist to assure all facility requirements have been met. ,
- A specific plan to be used during construc::on for observation, inspec-
tion and testing of subgrade, liner material, factory and field seam
•quality, installation workmanr-ip, and assurance that the design is
followed. Daily records must -e maintained of all aspects of the work
and all tests performed on the subgrade and liner. For example, air
lance seam testing with periodic field seam tensile testing.
- Throughout construction, a qualified auditor responsible to the
operator/owner should review and monitor output. This is an ongoing
check on the contractor/installer. It generates confidence that the
work was indeed done as planned. Changes to planned procedures must be
justified immediately and subsequently documented. This can avoid
serious conflicts between the owner and design/installation team after
the job is completed.
Quality control/inspection programs; can result in more effective impoundments
by assuring planned review and tracking of all activities comprising the
facility design and construction.
There are three major specific areas..of quality-control concern in a polymer
membrane lined impoundment. They are the subgrade, membrane seams, and
sealing of penetrations through the liner.
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A representative of the primary facility operator, or representative of :
ultimate owner of a lined facility, is usually assigned as the quality contr
agent or engineer on liner installations. The agent will be required
assure that the contractural obligations of the installing contractor(
are met and that the installation specifications are fully met. Personn
reviewing the design or performing quality control functions for a lin
installation should be familiar with the liner manufacturer's recommendatioi
regarding all facets of the material's use and installation. This includi
everything from the liner's compatibility with the waste being stored 1
recommendations regarding specific adhesive systems and special seamir
instructions around penetrations.
5.4.5.1 Subgrade
A quality control plan for the earthwork portion of the project serves tw
important functions. First, a uniform density is attained which assures bot
owner and engineer that the project is constructed as designed. Second, i
provides the data necessary to control costs when field densities are highe
than required: this eliminates the possibility of an increased volume o
earthwork (Small, 1980). A quality control program should specify the tesi
frequency to ensure accurate and reliable field density data and be tailorec
to the specific needs and requirements of the project. The factors to con-
sider in establishing a quality control program for earthwork include, but are
not limited to, the following:
1. Total project area.
2. Range of fi11 heights;
3. Number of soil types to be compacted.
4. Consistency of each soil type.
5. Haul distance.
6. Anticipated weather conditions.
7. Method of placement.
8. Method of compaction.
9. Geometry of the site.
It is a generally accepted practice to test each lift of soil placed. The
number of tests per lift may very from one to ten tests per 20,000 square
feet, depending upon the criteria developed for the project. Soil samples are
normally taken and tested to ascertain that the subgrade materials are of the
specified classifications and constituency. Measurements of moisture and
relative compaction are periodically determined to ensure that the subgrade
has the desired firmness. Visual observations of subgrade appearance,
earthwork activities and workmanship, lack of vegetation, drain orientation
and placement, curb and control of water as necessary, slope characteristics
and preparation, and other parameters are conducted on an 'as needed' basis.
In some instances, the original design of an impoundment must be modified in
the field to accommodate unexpected conditions and unforeseen occurrences.
Since membrane liner installations are new to many "earthwork" contractors,
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advice is often solicited from onsite personnel of the liner installer
fabricator, and/or manufacturer as unforeseen problems arise.
5.4.5.2 Flexible polymeric membrane liner M
The success or failure of the liner installation will depend to a great extent
upon the installing contractor's seam credibility. Job site factors which may
influence the field seaming operation include:
1. The ambient temperature at which the seams are produced.
2. The relative humidity.
3. The amount of wind.
4. The effect that clouds have on the liner temperature.
5. The moisture content of the subsurface beneath the liner.
6. The supporting surface on which the seam is bonded.
7. The skill of the seaming crew.
8. The quality and- consistency of the adhesive.
9. The cleanliness of the seam interface, i.e. the amount of airoorne
dust and debris present.,
Seaming methods differ between liner materials. Lured materials or vulcanized
materials such as £?OM and neoorene are usually sealed with a tongue and
groove type seam using gum tape or a two part system. Uncured or unvulcamzed
material such as CSPE, CPE, and PVC are sealed using solvent, bodied solvent^
adhesives, 'or heat. Contact adhesive systems may also be used, however they
do not develop the same seam strength as bodied solvent systems. Several
pictures of field seaming are presented in Append:* IV. A new seaming method
of fusion welding is shown in Figure 5-13.
Once the seam has been corneleted, it should be allowed to stand long enough to
develop full strength. The three basic requirements for credible seam pro-
duction by thermal methods are heat, pressure, and dwell time. In the case of
an adhesive system, the adhesive taxes the place of the heat. However,
sufficient pressure and dwell time must be applied to create permanent bonding
of the seam interface. An air lance test using 50 psi air directed through a
3/16" nozzle, held no more than 6" from the seam edge may be used to detect
any holidays, tunnels, or fishmouths in the seam area. Testing the integrity
of a seam, with a "vacuum box" such as is used to test steel welds is shown in
Figure 5-19 and an ultra-sonic method is also shown. Any imperfections should
be repaired as soon as practicable. Once testing has been completed any
exposed scrim (in the case of reinforced material) is to be flood coated with
the same bodied solvent adhesive. The entire impoundment should be inspected
to insure that all the field and factory seams are properly joined, no scrim
is exposed and any damage which may have occurred during installation has been
repaired. All patches should have rounded corners with the scrim properly
flood coated to insure encapsulation.
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Figure 5-13.
Seaming of HOPE liner with a fusion welder
Gundle Lining Systems.)
(Courtesy of
5.4.5.3 Penetrations
Penetrations of a membrane liner, e.g. inlets ana outlets, are a significant
concern witn respect to adequate sealing between the liner and the penetra-
tion. Where the penetration is round, stainless steel bands may be used.
Screw-type clamps are well suited for small penetrations four inches in
diameter or less. For larger pipes, "band-it" type methods may be specified.
An extra layer of liner material should be placed between the band and the
liner to prevent cutting or abrasion. Flange-type connections offer the most
secure type of seal between the liner and pipe penetrations. Flanges should
be set in concrete with anchor blocks tack welded to the back of the flange.
Care must be taken to insure that the concrete is smooth finished with rounded
edges. Additional layers of the liner may be placed over the flange extending
to the full edge of the concrete so as to form a gasket and also to prevent
abrasion between the concrete and the liner. Once the liner is placed over
the flange, an additional layer should be placed on top to form the other half
of the gasket seal (Small, 1980).
5.4.6. Earth Covers for Flexible Membrane Liners
Earth covers are commonly placed on polymeric,
liners for two principal reasons:
spray-on, and other membrane
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Figure 5-19.
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a. As a protective layer against mechanical, weather, and other environ-
mental damage.
b. As a relatively permeable layer in landfills for the drainage and
collection of leachate that is generated in the fill.
Most membrane materials have relatively little structural strength and some
are quite sensitive to such environmental conditions as:
- Ultraviolet light which can degrade polymeric materials if not proper-
ly compounded.
- Infrared radiation which by heating the liner can cause evaporation of
the volatile constituents and oxidative degradation of the polymer.
-Mechanical damage from solid waste primarily during placement in the
field.
- Wind, which causes increased evaporation of constituents in some liner
compounds, and possibly mechanical damage to the liner itself.
-Wave action in a pond or lagoon.
- Oxygen and ozone.
- Freeze and thaw.
- Hail and rain.
- Animals - hoofed, gnawing, etc.
- Vandal ism.
It may be necessary to place a soil cover after installation before the
filling of the facility can begin.
The need for soil covers for leachate drainage and collection purposes is
discussed in Appendix V. This soil cover in addition to being a part of the
drainage and collection system will also protect the liner from mechanical
damage during placement and compaction of solid waste. Generally these covers
are two feet or more in thickness.
The manufacturers of PVC liners recommend the placement of an earth cover to
protect the liner. Ultraviolet light degrades PVC material by causing
chemical changes to occur along the polymer backbone. These changes which can
cause embrittlement of flexible PVC liners can be avoided or minimized by
compounding the" PVC with UV light absorbers and other stabilizers. However,
it is recommended that PVC liners be covered regardless of the end use. Other
materials, such as CSPE, CPE, EPDM, and elasticized polyolefin are recommended
for exposed (noncovered) use. Manufacturers and installers of high density
polyethylene and of CSPE question whether the benefit of placing a cover is
worth the cost and the risk of potential damage to the liner. All polymeric
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membranes are susceptible to sun aging if not properly compounded. Thus, th
function of a cover in this case is to block out the sun and prevent su
aging.
In addition, a cover is necessary wherever vehicular traffic is anticipa^
over the liner though thick liners can resist damage of light vehicles. Ir
the case of waste impoundment facilities in which hot fluids are introduced,
the cover acts to protect the liner from the initial high heat factor anc
subsequently to insulate the liner from residual heat by decreasing the
temperature at the liquid/liner interface versus the temperature of the fluid
body. In the case of a lined wastewater treatment impoundment where mechan-
ical aeration is utilized, a cover may be required to mitigate the potential
for the liner to be drawn off the bottom or side by hydraulic wave action.
On-site weather conditions influence the use of a soil cover. In extreme
climates, such as the northern plains or the desert Southwest, covers are
often used to protect against mechanical damage due to freeze-thaw cycles and
subsequent ice movement, or sun degradation. Wastewater impoundments in the
northern states often become ice covered in winter. Spring thaws can result
in ice movement, greatly increasing the chances for damage to an exposed
1iner.
Other weather conditions often dictate the necessity for special design or
performance features. Hail can cause failure of some exposed liner .-natarial s,
particularly on flat bems wnere a thermoplastic liner 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 compen-
sations are not made in the design. _ .
The cover for a liner can also ""unction to reduce the impact of a chemical
aggressive or incompatible waste upon the liner. This occurs because of the
reduction of the liner surface area which comes in contact with the waste.
Furthermore, the cover will probably also reduce :°9 maximum concentrations of
waste that contact the liner.
The type of security measures to be incorporated into the operating plan at a
lined impoundment will influence the need for a soil cover. For example, if
the site is not fenced and wildlife and the public have easy access to the
site, then a soil cover will minimize vandalism or accidental damage.
Vertical slopes prevent animals from entering tne pond. One cannot build
economically a fence high enough to keep deer out..
From field experience, it has been found that the maximum side slope ratio
which will hold an earth cover over a smooth liner is three horizontal to
one vertical. The initial covering should be placed with a light tracked
bulldozer. The soil should be spread from a pile and .kept at a minimum
thickness of 18 inches. It is advisable that the moisture content of the
bedding be kept at or below optimum moisture content so that the soil compacts
readily with minimum effort. Subsequent layers of protection may be placed in
a similar fashion but with larger tracked bulldozers.
The placement of the soil covers, themselves, "increases the chance of puncture
of the polymeric liner, and once covered, punctures cannot be repaired. The
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principal requirements of a cover material are that it must be free of sharp
stone and other objects and that it be compatible with the waste that is to be
placed on it. The cover material should be stable and resist sloughing from
wave action, and should, wherever possible, be local material to k^p the
cost low.
Figure 5-20 shows examples of the placing of soil covers on membrane liners.
5.4.7. Use of Coupons to Monitor the Liner During Service
In light of the limited experience waste management has had with polymeric
membranes in the lining of waste disposal facilities and the lack of feedback
with respect to liner performance, it would be highly desirable to monitor the
condition of membrane liner materials during actual service. It is recom-
mended that samples or "coupons" of the same lot of liner material as used in
a disposal facility be appropriately placed in the impoundment before the
addition of the waste and be withdrawn on a planned schedule and tested.
Means to accomplish such a program must be incorporated in the original design
of the facility and plans made for the withdrawal and testing of the coupons
during service. The coupon should be one square foot in area or larger, and
incorporate a field seam. Coupon placement should allow for essentially the
same exposure and environment to the waste as the installed liner, safe and
easy access and retrievabi 1 ity, economical placement, precise location, and
precise identification. Thus, the design phase of a lined impoundment facil-
ity can contribute greatly to the overall success or failure of a coupon
testing and evaluation program. During the construction phase, the acces-
sibility and retrievabi1ity factors can be field tested, in addition to the
determination of the adequacy of space allocated for coupons. The testing and
evaluation program is a long-term ongoing procedure. Depending upon the
design function and life of the im'pouncment, :-e coupon program will peri-
odically yield information relating to the physical and chemical integrity of
the liner on which decisions concerning liner rec'acement or liner useful life
can be made. Exposure periods can range beyond twenty years or can be as short
as one year.
5.4.8. Gas Venting
Certain conditions require the venting of gas that may accumulate beneath a
liner. If organic matter exists in the soils under the liner, or if natural
gas is present in the region, gas production is inevitable. If a pond has a
flat bottom, gas will tend to accumulate under the liner. If the pressure is
permitted to increase, a membrane liner can be lifted creating a cavern for
additional gas accumulation. The higher the membrane bubble is allowed to
rise, the more the membrane stretches and the less hydrostatic pressure is
available to restrain the membrane. As a result, the membrane floats to the
surface.
Venting must also be. considered when a fluctuating water table is present
immediately below the pond 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 and
257
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. •»
•- • , •• . y- . jreij~^. _«
a son cove, over
258
-------
proximity of the water table to tne pond bottom, will dictate the reaction of
the membrane to this air pumping mechanism. The need to vent this accumulat-
ing gas is best accomplished by providing a layer of uniformly graded sand of
w.'ich less than 5% by weight will pass the 200 sieve. Also for membrane
liners, a geotextile may be used, which allows gas to pass through the fab-
ric's cross-section under a surcharge load. In order for these media to be
effective, the bottom of the pond must slope up from its lowest point to the
toe of the dike a minimum of 2% and the liner must De reinforced with a
fabric scrim. The venting medium is carried across the entire bottom, up the
side slopes. 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 dike. Simplified representations of two designs of gas vents for
membrane liners are illustrated in Figure 5-21.
5.5 PLACEMENT OF MISCELLANEOUS TYPES OF LINERS
5.5.1 Sprayed-on Liners
A basic problem in the placing of this type of liner is to make it pinhole
free. Spray-on liners require a more carefully prepared subgrade than other
liner types. The suogr-ade is dragged and rolled to produce a smooth surface
free from rough, irregular or angular projections. If the surface cannot
meet the above criterion, a fine sand or soil padding may be necessary for
proper memorane support. The site snould be excavated or over-excavated and
side slopes flattened to allow for any padding necessary before liner applica-
tion and for 1 to 3 feet of cover over the memorane (Bureau of Reclamation,
1963, p. 80-82).
Sprayed-on catalytically-blown asphalt membranes are heated to 200-220°C
(392-428°F) and applied at a rate of 1.5 gal/yd2 neasured at 60°F. The high
softening point asphalt snould not be overheated since tnis may lower tne
softening point and change other properties of the -naterial. The spray bar is
usually set off to the side of the distributor so tnat tne heavy equipment
does not travel over tne suograde or newly applied memorane. To eliminate
pinholes, it is recommended tnat tnree passes be made at a rate of 0.5 gal/yd^
each for a cumulative application of 1.5 gal/yd2 (Aspnalt Institute MS-12,
1976). The final_ membrane is usually about 1/-1 inch thick. Sections of
membrane snould be overlapped 1 to 2 feet. The newly applied hot aspnalt
melts tne underlying layer; botn cool to form one continuous liner. The
asphalt cools quickly and tne next pass with the spray bar may be made immed-
iately after finishing the previous layer. Care snould be taken to avoid the
accumulation of sand, silt, dust, or gravel on the asphalt between applica-
tions. .Foreign materials on the membrane prevent proper bonding of layers and
may cause pinholes to form.
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 5-22
illustrates large scale spraying equipment and the spraying of rubberized
asphalt.
259
-------
12'TO 18' 12'TO18'
"•:f§^§i
1 •?:<:.!
12" $
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S'f'.T"-''-'.'^;1""
ANCHOR
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, 1 m
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rt fl ^AIR-GAS VENT
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2" Dia. hole Thru sanel
Cover - to be sealed to PVC pipe
3i elbow and then seal to
•emforcmg panel
2" Dia. PVC pipe
• Reinforcing panel
Liner
Figure 5-21.
Designs of two different gas vents for membrane
lower design is based upon drawings supplied
Corporation.
liners. The
by Sta-Flex
260
-------
Figure 5-22. Placement of sprayed-on- liners. The upper photograph- shows a
spray bar attached ..to .a tanker truck and the lower photograph
shows the spraying of a rubberized asphaltic membrane (Courtesy
of Arizona Refining Company).
261
-------
Asphalt emulsions are sprayed at ambient temperatures (above freezing),
usually onto a supporting fabric of jute, glass or synthetic fiber. A con-
tinuous membrane forms after tne emulsion breaks and the water evaporates.
Several light applications are used, not only to avoid pinnoles, but to al
drying between coats to avoid porosity due to entrapped water.
Asphalt membranes are usually covered to protect them from mecnanical 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 drag-
lines should be done on the floor first then from bottom to top of tne side
slopes. Coarser materials may then be applied. (Bureau of Reclamation,
1963, pp. 82-83).
5.5.2 Placement of Soil Sealants
Asphalt emulsions may be injected into the subsurface. Special equipment is
used to inject the liquid six inches below the surface to form a continuous
membrane about 1/2 inch thick.
5.5.3 Placement of Chemisorptive Liners
Chemisorptive liners vary in form and type. Some are soil sealants, liquids
or powders, which are applied using methods similar to tnose used for bent-
onite or sprayed-on liners. Others are pozzolanic or cement-like. These are
installed and constructed following procedures similar to those used for
asphalt concrete or cement. Individual manufacturers or producers should be
addressed with questions concerning this class of liners.
5.6 LINERS AND LEACHATE MANAGEMENT FOR SOLID WAS" LANDFILLS
5.6.1 Environment of tne Liner in a Sanitary Landfill
The environment in which a liner nust function will ultimately determine now
well it can serve for long periods of time. The situation of a liner in a
sanitary landfill is represented schematically in Figure 5-23. Some of the
conditions at the base of a landfill snould nave no adverse effect on life
expectancy of a given material, whereas other conditions could be quite
deleterious. The effects can be different for different materials. Some
important condiditons that exist at the bottom of a MSW landfill in the
proximity of the liner and that may influence the life of a liner are:
1. The barrier is placed on a prepared surface that has been graded, to
allow drainage, compacted and free of rocks, stumps, etc., but may
settle to cause cracking of hard liners. A brittle or weak material
might fall.
. 2. Anaerobic condition with no oxygen t-o cause oxidative degradation.
3. No light, which normally degrades many polymeric materials.
262
-------
LEACHATE
DRAIN
OJLL HSI6HT
Figure 5-23. Schematic drawing of a lined sanitary landfill (Haxo, 1976).
4. Generally wet-humid conditions, particularly if leachate is being
generated regularly, that could result in the leaching of ingredients
from a 1 iner.
5. Cool temperatures of 40 to 70°F normally, although high tempera-
tures can be generated within the fill if aerobic decomposition takes
place.
6. Generally acidic conditions from the leachate due to presence of
organic acid.
7. High concentration of ions in the leachate that may exchange with
clay soil and increase permeab: . i ty .
8. Considerable- dissolved organic constituents in the leachate that may
swell and degrade some of the organic material liners.
9. Only modest head pressure, since drainage above the liner is
designed to take place continually. A porous soil is placed on top
of the liner before refuse is placed.
10.
The presence of the gases, carbon dioxide and methane, generated in
the anaerobic decomposition of the refuse. The carbon dioxide is
probably dissolved in the leachate and contributes to its acidity.
It may cause mineralization of the soil in the area of the liner.
The effects of these environmental conditions will differ on the various
barrier materials. However, it appears at present that mechanical failure
during installation or during operation of the fill due to settling of the
soil may be the most significant source of failure of a liner.
263
-------
5.6.2 Estimating Leachate Volume
The volume of leachate produced at a landfill site is primarily a function
the amount of water that flows through the refuse; in general, the J
that flows through the refuse, the more pollutants will be leached o
Precipitation is a key factor affecting the volume of leachate produce*
thus, in regions of moderate-to-heavy rainfall, leachate generation can 1
significant. For the designer of landfill leachate collection system;
however, a qualitative assessment that "significant leachate will be produce
at this site" is not sufficient. What is needed, rather, is a tool fc
predicting with a reasonable degree of accuracy the quantity of leachat
that a given landfill can be expected to produce under a number of differen
scenarios. Fortunately, within the last several years, such a tool ha
evolved, based on a water balance method developed by Thornthwaite and Ma the
(1955) in the soil and water conservation field. A computer model has bee
developed to simulate hydrologic characteristics of landfill operation
(Perrier and Gibson, 1982).
The water balance method is a kind of mathematical accounting process whict
considers precipitation, evapotranspiration, surface runoff, and soil moistun
storage, all of which have a bearing on the extent to which infiltration car
be expected to occur after a rain. Since infiltration is the major contrib-
utor to leachate generation, knowing how much can be expected under a giver
set of site conditions will provide the designer with valuable information on
which to base his recommendations. Such recommendations might specify the
soil types, drainage grades, plant species, or cover thicknesses required to
minimize or preclude leachate production. Similarly, leachate sumps, risers,
pumps, and treatment facilities can also be more rationally engineered
a water balance calculation has been made.
Three factors are of critical importance in a water balance calculation: soi 1
moisture storage, evapotranspi ration and surfacg .vater runoff. The first is
critical because a cover soil that has exceeded its field capacity (the
maximum amount of water a soil can retain in a gravitational field without
downward percolation) becomes a source of infiltration to the refuse which
may eventually lead to leachate production. Ideally, efforts by the design
engineer should be directed to ensuring that the cover soils and other
landfill features are selected and installed so as to keep the soil moisture
storage below field capacity. Assuming there is no groundwater infiltration
or other source of excess liquids, leachate production should not occur.
Obviously, some hydrologic regimes such as high rainfall and low evapo-
transpi ration make it uneconomical to achieve this condition at all times;
emphasis must then be shifted to determining how much leachate is apt to be
produced and what control-recovery-treatment options can be employed.
The amount of water that can be added to solid waste before reaching field
capacity depends on the moisture content of the waste at the time of placement
in the landfill. Moisture content at time of placement is not a constant, but
a function of waste composition, density and-cVimatic conditions. However, as
a rule of thumb, moisture content of the wastes at the time of placement, has
been found to range from 10 to 20 percent by volume (Fenn et al, 1975).
264
-------
As Table 5-4 indicates, refuse has a large capacity to absorb moisture
before leachate is produced. Leachate production will not occur at rates
equal to infiltration of rainfall until saturation is exceeded, a condition
significantly above field capacity. However, leachate production can occur by
channeling, a process by which net infiltration flows through openings or
channels within the refuse before the field capacity of the fill is reached.
TABLE 5-4. MOISTURE CONTENT OF REFUSEa
(Average Values)
Refuse at
Placement
Field capacity
Saturation13
Percent
by
volume
10-20%
20-35%
--
Equivalent
inches HpO/
ft of refuse
1.8"
3.6"
6.6"
Equi valent
gallons H20/
yd3 of refuse
30
60
110
aAdapted from: Fenn et a.l., 1975.
bBased on a 0.4 porosity for refuse.
The second most important variable, eyapotranspi ration, represents the amount
of water present in the soil that is lost to the atmosphere from a given area
through direct evaporation from the soil and transpiration from plant tissues.
When soil moisture is at or near field capacity, evapotranspiration occurs at
its maximum potential rate. However, as soil moisture approaches the wilting
point (the moisture content below which moisture is unavailable for withdrawal'
by plants), the amount of water available begins to restrict the rate of evap-
otranspi rati on, resulting in reduced actual water losses. The water balance
process takes this effect into account. While rates of evapotranspiration for
different parts of the country have been developed oy Thornthwaite and Mather
(1964), their method may not provide the best estimate for all areas of the
country. Thus, the design engineer has to. evaluate Thornthwaite's figures
versus other evapotranspiration data that could be.applied to each particular
area of interest.
The third parameter of major importance is surface runoff, i.e. that portion
of rainfall which will run off the site in Meu of entering the cover soil.
Variables affecting runoff include intensity and duration of rainfall, exist-
ing soil 'moisture, soil permeability, slopes, and type of vegetative cover.
Runoff can be calculated using empirical runoff coefficients commonly used to
design surface water drainage systems. By .multiplying the coefficients by the
mean monthly precipitation, a "mean monthly surface runoff" can be calculated.
Details on the actual calculations involved in using the water balance method
are presented in the appendix to an October 1975 EPA report (EPA-SW-168). In
brief, the basic equation for determining tha amount of percolation anticipat-
ed at the given site is as follows:
PERC - P - R/0 - ST - AET
265
-------
where,
PERC = Percolation, i.e. the liquid that permeates the refus^
P 3 Precipitation for which the mean monthly values are typical ty
used.
R/0 3 Surface runoff
ST = Soil moisture storage, i.e. moisture retained in the Suil
after a given amount of accumulated potential water loss or
gain has occurred.
AET = Actual evapotranspiration, i.e. actual amount of water loss
during a given month.
In using the water balance method to quantify the volume of leachate produced,
special field conditions at landfill sites should be considered. Variations
in cover depth and the absence of vegetation in some areas of the site will
influence leachate production.. More percolation thus occurs during the
operational phase due to such factors as absence of vegetation, shallow depths
of intermediate cover, surface cracks and lack of adequate drainage. As a
result, leachate may be produced sooner and in greater volume than was pre-
dicted by water balance calculations based on a completed landfill. Another
special condition that can result in a greater production of leachate than was
predicted by the water balance method is irrigation of the completed site for
a specific use such as a park or agricultural area. Since the irrigation
required to supply evapotranspirative demands of the growing vegetation is not
totally efficient, percolation can be significant and hence leachate produc-
tion can result. An additional field condition, tna: can have an impact on the
water balance calculations is the presence of frozen ground and/or snow
accumulation. Such a condition reduces the infi'tration of the precipitation
during winter months with the net effect on the *ater balance of decreasing
percolation and hence the quantity of leachate produced.
To illustrate the application of the water balance method in a variety of
climatic conditions, Table 5-5 summarizes data for the key water balance
parameters in three regions of the United States: Midwest, Southeast, and
Southwest. As the table indicates, the range of values for percolation of
moisture into refuse can vary widely depending on whether the site is in a
humid climate such as that found in the Midwest, or an arid climate, such as
that of Los Angeles.
Once the designer has estimated by means of the water balance method the
quantity of moisture that will percolate into the refuse, he is in a position
to make a decision concerning the type and size leachate collection facil-
ities. Applications of the water balance method to landfills in a broad range
of climatological conditions in the continental United States has shown a
range of percolation rates of 15 inches per year to 36 inches per year (as-
suming proper covering,' vegetation, and drafnage of the completed landfill
surface). These values provide a rule of thumb for use by the designer in
sizing leachate collection systems.
266 I
-------
TABLE 5-5 SUMMARY OF WATER BALANCE CALCULATIONS3
Percolatio
Cincinnati ,
Ohio
Orl
Fl
Los
Ca
ando,
orida
Angeles
1 ifornia
Local
soil
conditions
Clay
Loam
Sandy
Loam
, Silty
Loam
Precipitation,
mean
cm
102.5
134.2
37.8
annual
(in)
(40.
(52.
(14.
Su
rface
runoff
coefficient
4)
3)
3)
0
0.
0
.17
075
.15
Percolation
mean annual ,
cm (in)
:i.3 (8.4)
7.0 (2.76)
0
maximum
monthly
cm
6.6
2.5
0
0
(2
(1
n)
.6
)
aSource: Fenn et al . , 1975.
The major advantage of the water balance method is its flexibility in allowing
for modification of various input variables. This enables designers tc
compare the effectiveness of alternative control techniques by simply "run-
ning" the water balance model for each management plan. When used in conjunc-
tion with data on leachate quality and probably water quality impacts, the
water balance is an extremely effective tool.
Figure 5-24 illustrates the factors influencing percolation that may be manip-
ulated using the water balance method as a leachate management tool; thus, by
increasing several of the water balance variables, e.g. a final cover of low
permeability, leachate generation may be precluded. As shown in Figure 5-25,
surface runoff, soil moisture storage, and evapotranspi ration - key parameters
in the water balance equation - can be readily increased, thereby reducing
percolation of liquid into the wastes. Surface runoff can be enhanced by
(1) increasing drainage gradients, (2) selecting -ore impermeable cover soil,
(3) using a thicker and denser cover soil, (4) utilizing synthetic membranes,
(5) adding soil conditioners (chemicals, bentonite, etc.) to render the
existing cover soil less permeaole, and (6) implementing a good maintenance
program for graded surfaces. Like surface runoff, potential soil moisture
storage. can be increased by using thicker cover soil and by employing silt and
clay cover. Selecting highly evapotranspi rati ve vegetation that is tolerant
to landfill conditions enhances evapotranspi ration. Landfill slopes must be
graded to enhance runoff while minimizing erosion. The final surface of a
landfill should be sloped sufficiently to prevent water from pooling over the
surface (a minimum slope of 2% is recommended).
As noted earlier, not all climates and hydrogeologic environments enable
practical/economical prevention of leachate generation. Thus, in humid
climates where leachate generation is more difficult to preclude, the hydro-
geology of the site should be carefully evaluated to determine the potential
for natural inhibition of leachate production. At sites where the hydro-
geologic conditions are incapable of minimizing the impact of leachate on
underlying ground water, leachate "collection ' facilities should be employed.
Design criteria for such facilities are discussed in the next section and
Appendix V. . ....... ......
267
-------
•Y-'Y»Vll'niiiif iir'-' •'•'•'• 'VQ'IWCHJITE 'ATT£NUlfiflH '.-'
Figure 5-24.
Percolation through solid waste
into the soil environment.
ana movement of the leachate
5.6.3 Transmissivity of Leachate
When the infiltration of precipitation and other sources of water applied to
the landfill surface exceed the combined effects of runoff, evapotranspira-
tlon, and soil moisture storage, leachate will be produced in the landfill.
This net Inflow to the landfill, termed percolation on Figure 5-24, is absorb-
ed by the waste until the field capacity of the fill is reached, field capac-
ity here defined as the maximum amount of moisture a soil or solid waste can
268
-------
•/«>•»...»;; so 110 WASTE \'.-'V- V'.-V -
Figure 5-25. Preclusion of leachate production through use of proper drainage
grades and cover.
retain in a gravitational field without producing a continuous downward
percolation (Fenn et al., 1975). Thereafter, percolation ^nto the fill will
accumulate as leachate at the base of the fill or discharge to the soil-
groundwater regime beneath the landfill (see Figures 5-26 and 5-27).
When percolation occurs in a landfill located within a containment lined with
natural soil, constructed admixes, remolded clay soil, or manufactured mem-
branes, leachate will accumulate in the fill'. "Eventually, the leachate level
will rise until (1) the head created on the base of the landfill results in an
269
-------
unacceptable rate of discharge through the liner, or (2) it threatens to
discharge to the ground surface. Both conditions require the removal of
leachate to relieve the hydraulic head.
PRECIPIT1TION
EVJPO
Ltachatt cofUcfiori gip«
TO IEACHATE COLLECTION SUMP
Figure 5-26. Accumulation, containment, and collection of landfill leachate.
Figure 5-27 shows leachate saturation lines that would result under condi-
tions of leachate accumulation: (1) no withdrawal, (2) withdrawal through
waste fill only, and (3) withdrawal through a permeable medium.
Removal of leachate is accomplished by draining to a leachate collection
system consisting of perforated pipes installed in gravel-filled trenches and
discharging to sumps from which the leachate is pumped. The rate at which the
leachate is removed is directly related to the permeability of the media
through which the leachate must flow to the collection system. The permeabil-
ity and porosity (percent of voids of potential fluid storage) of various soil
materials and municipal waste fill are shown on Figure 5-28.
When the geohydrologic conditions beneath the fill require minimization of the
leachate head, leachate removal to sumps can be enhanced by the placement of
a highly permeable material such as sand or a geotextile over the base of the
landfill.
270
-------
II
EVIfO-
TXAMSPIIATION V
Figure 5-27. Accumulation, containment, collection, and withdrawal o.f land
fill leacnate showing saturation levels for different condi
tions.
Figure 5-29, based on a flow net solution, provides a method of determining
the maximum head that will result in a medium given the permeability, spacinc
of leacnate collection pipes, and percolation ra:e into a saturated fill. The
analysis assumes gravity flow to a water surface in the collection pipe
maintained below the base of the fill and a uniform daily percolation rate to
the withdrawal saturation line. Example calculations are also presented on
Figure 5-29.
5.6.4 Leachate Collection System Network
A leachate collection system generally consists of strategically placed
perforated drain pipe bedded and backfilled with drain rock. The pipe can be
Installed in a trench or on the base of the landfill. The system can be
Installed completely around the perimeter of the landfill or a complex network
or grid of collection pipes can be installed - the latter being used when
the areas Involved are very large and/or the allowable head buildup is quite
small (see Sec. 5.6.3 Transmjssivity). The collection system is drained to a
sump or a series of• sumps from which the leachate is withdrawn. Appendix V
discusses in detail the layout, sizing, installation, and selection of pipe
material for leachate collection systems. . A,series of charts and tables are
presented for use in the design and analysis of the leachate collection
system.
271
-------
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jrain.g. manual
For leachate flow conditions represented
>i. coJi.ciion pip. in Fl9- a' tne following equation approximates
the flow net solution:
,/K - (*,*
WHERE; q = uniform infiltration rate
K. = coefficient nf nftrm»»ahi 1 i f-u
«
c
3 1 /
\tov -4 _
"x/I i ° °
•-/+! • " I
I — il - i
- £ ;5 * o n
— ~* S e
1 - j I |
| ~* 1 i $ «
3 1 *» "
— \ 5 o
1 \ X W
y
h = head of leachate above
impervious liner
EXAMl'I El b = width of area contributing
to leachate collection pipe
For waste overlying the liner; with collection
pipes at 200' interval spacings:
q = 2"/month = .00548 '/day
K (wastes) = 10* cm/sec = 2.83'/day
b = 100' and q/K = 2 x 10
'0 from chartj b/h = 20; therefore, the
b head (h) acting on the liner = 5'
i EXAMPLE 2 .
For a 1' thickness of permeable material
overlying soil liner:
q = 2"/month = .00548 '/day
K (sand) = 2 x 10 cm/sec = SO'/day
b = 100 'and q/k = 1 x lo"4
From chart, b/h = 100; therefore, the
head (h) acting on the liner = 1'
DO
trial
on impervious liners using flow net solution
is a log-log plot with subdivisions shown on
/I 3 —
1 ' ' ' : ' / * l^"
1 jf c cu v. "S.
• '' s ' ~° "S 2» J°
i ' / 1 \ 13 .C 'F— wl
i XL. r-
X1 ' . , i - — . 3
• , ; • X , , < ^_ C o"
Xl < <•' c •— i -a
>^T i > _o ^ c
/ I 1 ™ i T3
-------
The spacing of leachate collection pipes will influence the maximum head of
leachate on the base of the fill, given a uniform rate of leachate percolation
to a saturated fill and the permeability of the medium through which the^
leachate is withdrawn. The configuration of the collection pipe network
varies depending on the head allowed over the landfill base liner: the
greater the allowable head, the greater the pipe spacing. As a minimum, the
leachate collection system should extend completely around the perimeter of
the site to provide absolute control of the level to which leachate can rise
on this critical boundary.
An interior grid system becomes necessary if the leachate head on-the base of
the fill must not exceed a specified value. The slopes and spacing of the
interior grid pipes are controlled to a large degree by the minimum base slope
of one percent. Placement of a layer of permeable material over the base of
the fill, coupled with the use of an interior collection pipe grid, may be
necessary in extreme cases where the development of a leachate head cannot be
tolerated.
5.6.5 Leachate Withdrawal and Monitoring Facilities
Landfill leachate control systems mist include facilities for (1) the monitor-
ing of leachate levels at the base of the landfill and (2) the withdrawal of
leachate to prevent buildup of a liquid level that would promote unacceptable
migration of leachate from the landfill.
The current state-of-the-art in landfill design uses sumps or excavated
basins located at low points on the base of the landfill to which a leachate
control system discharges. A riser pipe extending from the sump to the ground (
surface or to the surface of the fill provides tie means for removing the
leachate from the sump in addition to providing a "well" in which leachate
levels can be measured. Leachate sumps are filled with drain rock that
provides the necessary storage capacity (pore soace) while also present-
ing transmissibi1ity characteristics necessary to produce flow to the
withdrawal pump at a rate adequate to maintain the gravity flow from the
col lection system.
The riser pipe is perforated or slotted along the section' immersed in the
drain rock filled sump and may be connected to a perforated header pipe in the
sump to allow a higher rate of flow to, and withdrawal from, the riser pipe.
5.6.5.1 Spacing and capacity of sumps
Sumps must be located with a frequency, capacity, and configuration such that
the leachate control system will drain by gravity to the sump when leachate
is being produced at the maximum anticipated rate. Frequently, the locations
of sumps are dictated by excavation requirements and collection system config-
urations. Hazardous -.ste landfill sumps should have a leachate storage
volume equal to or greater than three months expected leachate production but
not less than 1000 gallons. Assuming 'a porosi'ty of 0.4 (fraction of gravel
volume that is voids), the minimum volume of the sump that will be filled with
rock must be at least 12 cubic yards.
274 1
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The drain rock must be (1) free of fines that could reduce the transmissivi
of the rock, (2) of a sufficiently coarse gradation so it does not enter ti
perforations or slots in the withdrawal pipe, (3) nonsoluble in an ac-
environment and (4) sufficiently protected from fines entering from adjacer
soil and/or refuse. Satisfactory performance can be expected (Young et al
1982) if the drain rock gradation and perforation, diameter, or slotting widt
selected for the drain pipe satisfies the following U. S. Army Corps a
Engineers (1955) criteria for gradation of filter materials in relation t
pipe openings:
For siots:
Doc filter material
P.? = 1 2
slot width
For circular holes:
035 filter material
hoie diameter
= 1.2
The -Bureau of Reclamation (1973) uses the following criterion for grain size
of filter materials in relation to openings in pipes:
035 of the filter nearest the pipe
maximum opening of drain pipeor more
where D85 is the screen size through which 35% of the drain rock (by weight)
could pass.
Cedergren (1967) suggests that the above equations represent a reasonable range
over which satisfactory performance can be expected.
Figure V-2 in Appendix V can be used to determine the required sumo capacity
or withdrawal rates needed to ensure gravity flew *rom the leachate collection
system under the maximum discharge rate. To determine the required capacity
or withdrawal rate (1) locate on Figure V-l , also in Appendix V, the percola-
tion rate that has been previously calculated by the water balance method, (2)
rise vertically from the horizontal axis to the line corresponding to the
average width of area tributary to the leachate collection oipe(s), and (3)
move horizontally from the junction in (2) above to the vertical axis and read
the flow per 1000 feet of collection pipe tributary to the sump.
5.6.5.2 Monitoring and withdrawal
The riser pipe extending from the leachate sump must be of a diameter that
will accommodate a pump suction line in shallow facilities or a submersible
pump or air pump when the depth to the sump is greater than 20 to 25 feet.
Due to the corrosive nature of leachates, inert pipe materials such as PVC or
the equivalent should be used. The riser pipe can be installed in a trench
excavated in the wall of the landfill or disposal trench excavation to protect
the pipe from construction damage and stresses due to settlement of the fill.
Alternatively, the riser can be installed vertically from the sump. To
275
-------
protect the riser pipe, it is advisable to install vertical risers within a
larger diameter protective casing 'with the annular space filled with sand or
fine gravel. _
Typical construction details for leachate monitoring and withdrawal wells with
vertical and inclined risers are shown on Figures 5-30 and 5-31 respectively.
final toil cov«r
PVC cap
(or v«nf)
Concrtt* COD
18 « 18 !r»ncfl .n »loo«
(Fill with drain rocx)
Blanker of
3ermea6le material
collaction drain
8 PVC
— ~Two 5' long >«cfions of
3 ' "nadsr OID«,
perforated
• 5 mm
Figure 5-30. Typical inclined leachate monitoring and removal system.
5.6.6 Covers and Closure of Lined Waste Impoundments
Covers and closure are required for all lined waste impoundments. In addition
to protecting the surrounding environment, covers should provide aesthetically
pleasing appearance. The subject of covers is presented and discussed in
detail in the Technical Resource Document "Evaluating Cover Systems for Solid
and Hazardous Materials" (Lutton, 1982), a companion study to this document.
The closure of a lined waste impoundment facility involves several components
and procedures. This fairly complex operation is described in detail in a
companion TRD, "Closure of Hazardous Waste Surface Impoundments" (EPA, 1982).
276
-------
•Final soil cover
•Waste fill
Leachate
collection drain-
•PVC Cap
L°J
•——8 PVC riser pipe
•Granular material-placed with slip form
or permanent protective casing
Blanket of permeable material
Two 5' long sections of
8" header pipe, perforated
Drain rock
- 5 mm.
. 15 * 15 mm sump
(Fill with dram rock)
Figure 5-31. Typical vertical leachate monitoring and removal system,
277
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REFERENCES
Chapter 5. Design and Construction of Lined Disposal Sites
APHA - AWWA - WPCF. 1975. Standard Methods for the Examination of Water and
Waste Water. 14th ed. American Public Health Association, Washington,
DC. 1193 pp.
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. Issued Annually. Annual 3ook of ASTM Standards. American Society for
Testing and Materials, Philadelphia, PA. Several Parts.
Amster, K.H. 1977. Modulus of Soil Reaction (£') Values for Buried Flexible
Pipe REC-ERC-77-1. Bureau oiC Reclamation, U.S. Department of the Inter-
ior. 58 pp. ' _
The Asphalt Institute. 1966. Asphalt Linings *or Waste Ponds. (IS-136)
College Park, MD. 10 pp.
The Asphalt Institute. 1976. Asphalt in Hydraulics. (MS-12) College Park,
MD. 65 pp.
Black, C. A., ed. 1965. .Methods of Soil Analysis. Vol. 1. Agronomy Series
No. 9. Am. Soc. Agron., Madison, WI. pp. 210-221.
Brown and Root, Inc. 1978. Largest Soil-cement Job Coats Reservoir Embankment.
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, DC. 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, DC. 627pp.-. •• •-.
Bureau of Reclamation. 1977. Design of Small Dams. 2nd ed. Revised
reprint. U.S. Government Printing Office, Washington, DC. 816 pp.
278
-------
Burke Rubber Co. 1973-1979. Product Installation Information, San Jose, C
Burmister, O.M. 1964. Environmental Factors in Soil Compaction. In: AS'
Symposium, Compaction of Soils. STP 377. American Society for Testii
and Materials, Philadelphia, PA. pp. 47-66.
Cedergren, H.R. 1967. Seepage, Drainage, and Flow Nets. John Wiley and Son:
Inc., NY. 534 pp.
Chelapati, C.V. and F.R. Allgood. 1972. Buckling of Cylinders in a Confinin
Medium. Soi1-Structure Interaction: A Symposium. HRB Record No. 413
HRB, Washington, DC. pp. 77-78.
Cheremisinoff, N.P., and P.M. Cheremisinoff. 1978. Fiberglass-Reinforce*
Plastics Deskbook. Ann Arbor Science Publishers, Inc., Ann Arbor, MI,
328 pp.
Clarke, N.W.8. 1968. Buried Pipelines, A Manual of Structural Design anc
Installation. Maclaren and Sons. London. 309 pp.
Coates, D.F. and Y.S. Yu. Eds. 1977. Pit Slope Manual Chapter 9 - Waste
Embankments. CA'NMET Report 77-1. Canada Center for Mineral and Energy
Technology, Ottawa, Canada. 137 pp.
Davis, S.N. , and R.J.M. DeWiest. 1966. Hydrogeologv. John Wiley and Sons,
Inc., NY. 463 pp.
Day, M.E. 1970. Brine Pond Disposal Manual. Office of Solid Waste Contract No.
14-001-1306. Bureau of Reclamation, U.S. Department of the Interior,
Denver, CO. 134 pp.
EarthTech Research Corporation. 1982. Assessmert of Innovative Techniques to
Detect Landfill Liner Failings. Final Report, Contract 53-03-3029. In
Press. U.S. Environmental Protection Agency, Cincinnati, OH.
EPRI. 1979. FGD Sludge Disposal Manual. FP-977. Electric Power Research
Institute, Palo Alto, CA.
EPA. 1977. Procedures Manual for Ground Water Monitoring at Solid Waste
Disposal Facilities. EPA-530/SW-611. U.S. Environmental Protection
Agency, Cincinnati, OH. 269 pp.
EPA. 1978a. Hazardous Waste Guidelines and Regulations. (40 CFR Part 250),
Fed. Regist. 43:58946-59028. December 18, 1978
EPA. 1978b. Landfill Disposal of Solid Waste, Proposed Guidelines. (40 CFR
Part 241), Fed. Regist. 43:18138-18148. March 26, 1979.
EPA. 1978c. Proposed Criteria for Classification of Solid Waste Disposal
Facilities. (40 CFR Part 257)... Fed. Regist. 43: 4842-4955. February 6,
1982.
279
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EPA. 1979. Methods for Chemical Analysis of water and Wastes. EPA-600/
4-79-020. Environmental Monitoring and Support Laboratory, Office of
Research and Development, U.S. Environmental Protection Agency, Cincin-
nati, OH.
EPA. 1980a. Test Methods for Evaluating Solid Waste, Physical/Chemical
Methods. SW-846. U.S. Environmental Protection Agency, Washington,
DC.
EPA. 1982. Closure of Hazardous Waste Surface Impoundments. SW873. U.S.
Environmental Protection Agency, Washington, DC.
Fenn, D.G., K.J. Hanley, and T.V. DeGeare. 1975. Water Balance Metnod for
Predicting Leachate Generation From Solid Waste Disposal Sites. EPA
530/SW-168. U.S. Environmental Protection Agency, Washington DC. 40
PP.
Freeze, R.A., and J.A. Cherry. 1979. Groundwater. Prentice-Hall, Inc.,
Englewood Cliffs, NJ. p. 29.
Goodrich, 8.F. Company. 1973. F'lexseal Liners - Manufacturer's Installation
Booklet.
Goodrich, 8.F. Company. 1979. Product Information Publications.
Haxo, H.E. 1976. Assessing Synthetic and Admixed Materials for lining
Landfills: In: Proc. of Researcn Symposium; Gas and Leachate from
Landfills - Formation, Collection, and Treatment. EPA-600/9-76-004.
U.S. Environmental Protection Agency, Cincinnati, OH. pp 130-158.
Hoeg, K. 1969. Stresses Against Underground Structural Cylinders. J. Soil
Mech. Found. Div., Am. Soc. Civ. Eng. 94 .' SM4) : 833-853. Paper 6022.
Highway Researcn Board. 1972. Soi1-Structure Interaction: A Symposium.
Highway Research Record No. 413. HR8, Washington, DC. 103 pp.
Janson, L. 1974. Plastic Pipe in Sanitary Engineering. Celanese Piping
Systems. Hi Hard, OH.
Kays, William B, 1977. Construction of Linings for Reservoirs, Tanks and
Pollution Control Facilities. Wiley Interscience, John Wiley and Sons,
Inc., NY. 379 pp.
Lambe, T.W. and R.V. Whitman. 1979. Soil Mechanics, SI Version. John Wiley
and Sons, NY. 553 pp.
Luscher, U. 1966. Buckling of Soil-Surrounded Tubes. J. Soil Mech. Found.
Div. Am. Soc. Civ. Eng. 92 (SMS):211-228.
Lutton, R. J. 1982. Evaluating Cover-Systems"for Solid and Hazardous Waste.
SW867 (Revised Edition). U.S., Environmental Protection Agency, Wash-
ington, DC.
280
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McWhorter, D.3., and J.D. Nelson. 1979. Unsaturated Flow Beneath Tailinc
Impoundments. J. Geotech. Eng. Div., Am. Soc. Civ. Eng. 105(GT11):
1317-1334.
Middlebrooks, E.J., C. Perman, and I. Dunn. 1978. Wastewater Stabilizatlor
Pond Linings, Special Report 78-28. U.S. Corps of Engineers. Cold Region;
Research and Engineering Laboratory, Hanover, NH. 116 pp.
Mitchell, J.K. 1956. The Fabric of Natural Clays and its Relation to Engineer-
ing Properties. Proc. Highway Research Board. 35:693-713.
Mitchell, J K. 1964. Panel Discussion. In: ASTM Symposium, Compaction of
Soils. ASTM STP 377. American Society for Testing and Materials,
Philadelphia, PA. p. 80.
Mourn, J., and I. Rosenquist. 1961. The Mechanical Properties of Montmori11oni-
tic and Illitic Clays Related to the Electrolytes of the Pore Water.
Proc. 5th Int. Conf. Soil Mech. Found. Eng. 1:263-267.
Perrier, E.R., and A.C. Gibson. 1982. Hydrologic Simulation on Solid Waste
Disposal Sites (HSSWDS). SW363 (Revised Edition). U.S. Environmental
Protection Agency, Wasmngton, DC.
Plastics Pipe Institute. 1973. Poly (Vinyl Chloride) (P'/C) Plastic Piping
Design and Installation, Technical Progress Report. PPL, NY.
Plastics Pipe-Institute. 1975. Polyvinyl Chloride Plastic (PYC) Gravity Sewer
Piping Systems. Technical Report PPI-TR25. PPI, NY.
Seed, H.B. and C.K. Chan. 1959. Structure and Strength Characteristics of
Compacted Clays. J. Soil Mech. Found, uiv., Am. Soc. Civ. Eng.
85(SM5):37-12S.
Seed, H.3. O.K. Mitchell, and C.K. Chan. I960. The Strength of Compacted
Cohesive Soils. In: Research Conference en Shear Strength of Cohesive
Soils. Sponsored by the Soil Mechanics and Foundations Division, ASCE,
Univ. of Colorado, Boulder, CO. pp 377-964.
Sherard, J.L., R.J. Woodward, S.G. Gizienski, and W.A. Clevenger. 1963. Earth
and Earth Rock Dams, John Wiley and Sons, NY. 725 pp.
Shultz, D.W.' 1982. "Ca-s History for Lined Impoundment. Draft. Grant No.
R806 645-010. U._. Environmental Protection Agency, Cincinnati, OH.
Shultz, D.W. and M.P. Miklas. 1980. Assessment of Liner Installation Proce-
dures. In: Disposal of Hazardous Waste - Proceedings of the Sixth Annual
Research Symposium. EPA 600/9-80-010. U.S. Environmental Protection
Agency, Cincinnati, OH. pp.135-159.
Skempton, A.W. 1953. The Colloidal Activity of Clays. Proc. 3rd Int. Conf.
Soil. Mech. Found. Eng. 1:57-61.
281
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Snail, 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, ACS, Las Vegas, NV. John M. Gifford Library, Akron, OH.
VII-1 - VII-46.
Sowers, G.F. 1979. Introductory Soil Mechanics and Foundations: Geotechnical
Engineering. 4th ed. MacMillan Publishing Co., Inc., NY. p. 97.
Spangler, M.G., and R.L. Handy. 1973. Soil Engineering. 3rd ed. Int. Edu-
cational Publishers. NY. 748 pp.
Terzaghi, K. 1955. Evaluation of Coefficients of Subgrade Reaction. Geo-
technique, V (4):297-326.
Thornthwaite, C.W., and J.R. Mather. 1955. The water Balance. Publications
in Climatology 8(1):104.
Thornthwaite, C.W., and J.R. Mather. 1957. Instructions and Tables for
Computing Potential Evapotranspiration and the Water Balance. Publica-
tions in Climatology 10(3):185-311.
Thornthwaite, C.W. 1964. Average Climatic Water Balance Date of the Conti-
nents. Publications in Climatology 17(3):419-615.
Todd, O.K. 1959. Groundwater Hydrology. Jinn Wiley and Sons, Inc., NY.
p. 53.
Uni-Bell. Recommended Practice for the Installation of Polyvinyl Chloride^
(PVC) Sewer Pipe. Uni-Bell Plastic Pipe Association. Dallas, TX. ^
U;S. Army Corps of Engineers. 1955. Drainage arc Erosion Control-Subsurface
Drainage Facilities for Airfields. In: Engineering Manual, Military
Construction. U. S. Army Corps of Engineers, Washington, DC. Part XIII,
Chapter 2.
Woodley, R.M. 1978. How to Select, Install and Prevent Damage to Membrane
Liners Used in Settling Ponds. Pulp and Paper Buyers Guide, 1979.
Young, C.W., T.J. Nunno, M.J. Jasinski, D.R. Cogley, and S.V. Capone. 1982.
Clogging of Leachate Collection Systems Used in Hazardous Waste Land
Disposal Facilities. Draft. U.S. Environmental Protection Agency,
Research Triangle Park, NC.
282
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CHAPTER 6
MANAGEMENT, OPERATIONS, AND MAINTENANCE
OF LINED WASTE DISPOSAL FACILITIES
6.1 INTRODUCTION
The proper management of a lined waste disposal facility is important if tt
performance of the impoundment is to be maintained and the maximum life e
the liner and the design criteria are to be realized. Special measures mus
be taken into account in the management of facilities that are lined. It i
necessary:
a. To protect the integrity of the impoundment and of the liner.
b. To monitor the performance of the liner system to determine whethei
it is operating within the design criteria and is not failing, i.e.
monitor the groundwater, the drainage system below the liner, piping
pumps, etc.
c. To monitor the.condition of the liner to determine if there are any
abnormal swelling, degradation, or changes in properties.
6.2 STANDARD OPERATING PROCEDURES FOR A WASTE ::5?OSAL FACILITY
The two basic type of impoundments to be encountered are:
a. Pits, ponds, and lagoons.
b. Solid waste landfilIs.
The first group of impoundments are all open where the liner may or may not be
exposed to the weather. Depending upon the materials and the construction,
the liner may be protected by various types of covers. In the case of land-
fills, the liners will be buried for most of their service lives (see Chapter
5). Several standard handbooks and manuals are available on the operations of
such impoundments. (EPA, 1978; ASCE, 1976; EPA, 1973) However, in the case
of lined impoundments, additional information should be incorporated in the
standard operating procedures manual for the specific disposal facility. The
additional requirements and procedures in an operating manual should reflect
the specific type of material that was used and construction details. The
operating and procedures manual should be prepared by the design, construc-
tion, and operations team and should include, as a minimum, the following:
- Operation and maintenance staff requirements and structure.
- Facility description and design parameters.
283
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- Emergency shut-down procedures.
- Operation variables arid procedures.-
- Facility trouble shooting procedures.
- Preventive maintenance requirements.
- Specialized maintenance procedures.
- 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 deletion;
to procedures.
6.3 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. Of particular importance is
information on the liner, and information on its characteristics and prop-
erties. This information should be obtained from the supplier, manufacturer
of the liner, the designer of the site, and the installer. Quality control
data and "as-built" drawings ana information should also De obtained. Samples
of the liner material and other ccmoonents should be retained for possible use
in cases of malfunctioning of trie impoundment. A full discussion snould be
obtained from the supplier as t3 tne limitations of tne '"ner material. The
material was selected on the basis of its compatibility w:th the wastes which
it will contain; consequently, deviations in the waste ccmoosition from the
anticipated composition should be avoided. Information of this type should be
incorporated into the operating manual and into the operator training program^
6.4 CONTROL OF INCOMING WASTE
As indicated in the previous section, the comoosition and character of the
waste must Pe controlled to avoic possible damage to the liner system. It is
recognized that a control will be maintained of the hazardous materials that
go into the impoundment. However, there is an additional requirement to avoid
materials that might be aggressive to the liner. An approximate analysis
should be performed on incoming waste to determine the amount of such con-
stituents in the waste. Compatibility of the incoming waste with the wastes
in the impoundment should be assured. Generally, there will be some dilution;
however, the added waste may have a synergistic and damaging effect upon the
liner. The operator should develop a knowledge of tne types of industries in
the area to be aware of those materials that might be encountered as wastes
for the disposal.
Liquids or sludges to be placed in a landfill may be solidified by mixing with
soil, a suitable dry absorbent, or by addition of selected chemicals. Drums
of liquid hazardous wastes are, in general, not allowed in landfills.
In order to know the contents of the Waste impoundment, records should be kept
of the wastes being disposed. This, of course, is being done to meet the
284
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standard requirements; however, the organic and inorganic constituents thai
are aggressive toward liners should also be recorded. The waste should b«
analyzed periodically in order to know its composition. -Chemical reactions
and volatilization of the constituents within the waste impoundment will
probably change the composition of the waste. Adequate means should b€
incorporated in the design of the impoundment for the addition of wastes.
Over-the-edge dumping of wastes should be avoided, as should the addition of
hot waste directly on a liner. "Sacrificial" covers have been used on slopes
to avoid damage to a liner when wastes have been dumped over the edge. These
covers can be replaced when they have deteriorated. Specially designed covers
and troughs have also been made for this purpose.
6.5 MONITORING THE PERFORMANCE OF "HE IMPOUNDMENT
The principal purpose of the impoundment is to contain a waste and prevent
pollutants from leaving the impoundment. Consequently, the principal means of
measuring the performance of such an impoundment is to monitor either a
drainage system below the liner or the groundwater. These techniques are
described in EPA (1977). In addition, the leachate collection system, if
leachate is being collected above the liner, should be inspected for the
output and composition of the leachate. It is recognized that considerable
time may elapse before the generation of leachate.
If a diversion drainage system is set up around the impoundment, this should
be inspected periodically to insure that drainage is being diverted.
6.6 MONITORING THE LINER
A system of monitoring the liner should be devised and, if necessary, incor-
porated in the design of the liner system to ooserve the condition of the
liner itself. The use of coupons at the bottom of a fill or other impoundment
has been discussed in Chapter 5. A program or retrieval of these coupons
should be set up to cover the operating time of the impoundment before it is
closed.
Any damage to a liner that is observed should be repaired as quickly as
possible in order to avoid a massive failure, openings in the liner can cause
damage to the earthwork below. The vents should be inspected regularly to
avoid plugging.
Impoundments holding wastewater may require cleaning to remove s
must be taken during cleaning so as not to damage the liner. C
should be supervised by someone familiar with the liner to asst
tures or tears are prevented, or patched if they occur. If
require cleaning to remove sludges. Care
' ' ' ^' " ' ". Cleaning crews
assure that punc-
If sludge is to
be removed from the bottom of a wastewater impoundment, some type of non-
mechanical means should be used, e.g. a suction hose or dredging head. This
should minimize the potential for liner damage.
Following cleaning, the liner should be thoroughly inspected for its condition
and possible distress.
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6.7 CONDITION OF EARTHWORK
In the case of ponds and lagoons, regular inspections should be made of th
embankments and berms. Attention should be given to possible ground mova
rents, cracks, and erosions of the earth. Since an erosion control probfl
usually exists when earth is exposed on an embankment slope, preventiv*
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.
6.7.1 Vegetation Control
Growth of vegetation must be controlled around the perimeter of any impound-
ment. This must be accomplished to prevent damage to the liner from the
anchor trench down the side slope. Damage can result if weed growth begins
under the liner or, if a soil cover is present, on top of the liner. In the
latter case, roots of plants can penetrate the liner creating a potential
failure point. Ideally, the berm area around the impoundment should be
treated with weed killer initially, and maintained in a weed-free condition.
6.7.2 Rodent Control
Rodents, such as gophers, squirrels, rats, muskrats, and mice, can present
severe problems for the owner of a lined impoundment. These animals will
attack and possibly damage a liner if the liner blocks their path to food or
water. Rodents have also been known to eat PVC material, particularly certain
ground squirrels. The presence of these animals at the construction site
should be assessed during design. Provisions to control their impact can then
be made and incorporated into construction.
6.8 INSPECTION OF APPURTENANCES (
Many of the failures of liner systems occur at penetrations of the liner by
appurtenances. Whenever possible, these should oe inspected on a regular
basis to check their integrity and make the needed repairs.
6.9 GENERAL COMMENTS
It is desirable to make on-site inspection of the impoundment on a regular
basis and to perform preventive maintenance.
"Vandalism and unauthorized dumping of wastes must be carefully monitored.
These may be curtailed by having limited vehicular access to the disposal
site, locating the site out of general view, and by fencing in ponds and
similar impoundments.
Inasmuch as liner technology is relatively new and basic experience is limit-
ed, good records should be kept of the performance of the sites. Failures and
difficulties should be noted.
6.10 UNACCEPTABLE PRACTICES
Certain operational procedures are not acceptable if the integrity of the
lined waste impoundment facility is to be maintained. These procedures
include, but are not limited to, the following:
286 ,
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ficient standing liquid levels. "° ™" "ver or •"<" ,nsu.
0. The passage of any vehicle over any portion of an
c. The discharge of incompatible wastes to the facility.
e. Unauthorised modifications or repairs to the facility.
287
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REFERENCES
ASCE, Solid Waste Management Committee. 1976. Sanitary Landfill. Manual
and Reports on Engineering Practice. No. 39.
EPA. 1973. Training Sanitary Landfill Employees. SW-43c. 1. U.S. Environmenta
Protection Agency, Washington, DC. 203 pp.
EPA. 1977. Procedures Manual for Ground Water Monitoring at Solid Wasti
Disposal facilities. EPA/530/SW-611. U.S. Environmental Protectior
Agency, Washington, DC. 269 pp.
EPA. 1978. Process Design Manual - Municipal Sludge Landfills. EPA-625/
1-78-010. SW-705. U.S. Environmental Protection Agency, Washington, DC.
269 pp.
288
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CHAPTER 7
COSTS OF LINING MATERIALS FOR WASTE DISPOSAL FACILITIES
Based on known performance information and given the proper design of <
facility, it appears that a number of technically suitable materials can b<
selected for lining a specific disposal facility. Costs, therefore, may be ar
important factor in the ultimate selection of a lining material. Although the
liner is only part of the total construction of such a facility, its cost car
be a significant factor in overall costs. Consequently, the costs of liners
will be considered by designers and engineers in their selection of a specific
material for a waste storage or disposal impoundment.
7.1 GENERAL FACTORS CONTRIBUTING TO THE COSTS OF LININGS
A wide range of factors are involved in the cost of lining materials.
Some of these factors are:
- The type of material used. Materials costs are essentially determined
by the prices of the raw materials necessary to the manufacture-of the
liner. An on-site soil, if it is found to be suitable, will probably
be the least expensive. A choice between other materials may be made
on a cost-benefit basis.
- The location of the facility and the trarsoortation costs involved in
bringing the lining material or fill to ~r,e site. Liner projects in
remote areas with rugged terrain will nave higher costs than sites
with more favorable topography and geology or located nearer to the
source of liner materials.
- As with most construction activities, the time of the year affects
labor availability and productivity. In addition, inclement weather
can disrupt liner installation. In the case of membrane liners,
successful field seaming requires a fairly narrow range of environ-
mental conditions; such liners cannot be placed in excessive heat or
cold, snow or rain, or on nonstable or wet ground. Delays in con-
struction and liner placement can thus result. Adverse weather con-
ditions can affect the placement of other liner materials as well.
- The size of the disposal facility can have a significant effect upon
the cost per unit area of liner As with most projects and construc-
tion materials, the larger the contr-act, the lower the unit cost of
work productivity and materials. Large liner projects usually have
significant economies of scale.
289
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- Type of soil on site. Regardless of whether the on-site soil is use
as the lining material or as the subgrade for either a liner fabricate
on the site or a prefabricated liner, thp type and condition of M
soil can affect costs. Sand or a soil with a limit on the maxiH
particle size may be needed as a bedding for membrane liners. A porou
soil cover is a necessary part of a landfill liner system. It i
needed for leachate drainage and collection and to protect the membran
liner against damage by equipment such as tracked vehicles and compac
tors that operate above the liners to compact the refuse. However, a:
all liners for MSW landfills need to be covered, the cost of the soi'
cover itself will essentially not be affected by the choice of liner.
- The differences in the properties of the lining materials may have a
small effect upon the cost of site preparation and installation of
liners, particularly in soil compaction and subgrade preparation costs
and the need for relatively small particle size bedding on which to
place membrane liners. Also, a herbicide may be needed with some
liners to prevent puncturing by plant growth under a newly laid mem-
brane.
- Differences in installation costs, such as field seaming of the sheet-
ing or panels into the final liner. Some materials will require more
work effort and quality control than others. Final installed costs
will take into account these differences, however.
During the past several years, cost data have been developed. They were
reviewed fn October 1973, updated in 1977, and resurveyed in 1981. Generally,
the 1973 and 1977 estimates die not include the costs for site and surfac^
preparation, which are essentially the same for all liner types, nor the costs'
of the soil cover on the liner needed in landfill construction. The cost
estimates for 1980 and 1981 include actual winning bids for liner jobs. Major
technological advances have oc" -red since 1973, as well as large cost in-
creases. The estimates for 198C and 1981 include subgrade preparation unless
otherwise noted.
7.2 POLYMERIC MEMBRANE LINERS
Prices for the membra'ne liners are quoted in a variety of ways:
- As "rolled goods" or sheeting as produced by liner manufacturers.
- As fabricated liners, e.g. those produced by the factory-seaming of
sheeting into large panels which are then sold to installers.
- As final installed costs which involve the assembly of the panels at
the site.
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. in-
stalled costs.
290
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As the polymer membrane industry is a minor segment of the polymer industr
raw material costs are set by producers of polymers and of other ingredien
of the liner compound. Because polymer materials, in turn, are made
chemicals from petroleum sources, costs ultimately are dependent upon costs
natural gas or crude oil feedstocks. The price increases of these petrole
commodities resulted in the corresponding rise in polymer costs for membra
production throughout the 1970s. Recent (1980-1982) economic factors ha
reduced the bid prices for liner projects.
Estimated cost data for polymeric membrane liners are presented in Tab
7.1. The unit costs shown cover the period 1973 - 1981 and reflect install*
cost only. They do not necessarily represent the total cost of a line
system, as other system components such as groundwater monitoring wells m«
be required. Also, the costs presented do not reflect equal service life c
performance of the liners.
Since 1980, however, several factors have contributed to the moderatio
of monomer and polymer prices. First, reduced capital expenditures hav
severely curtailed demand for polymers in many major markets, such as housing
automobiles, commercial construction, packaging, and aerospace, each of whic
uses hundreds of millions of pounds of these materials. Second, there is
large over-capacity for chemical polymer production which has led to signif
icant discounting from list prices of polymers. These recent trends are no
reflected in the cost data presented.
7.3 SOIL, ADMIX, AND SPRAYED-ON LINERS
Cost estimates for soil, admix, and sprayed-on asphalt membran'e liners
are presented in Table 7.2. The original data were collected in 1973 and
updated periodically. The data for 1980 show :ne most recent update. .As
with the polymeric membrane liners, 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 geograpnic location, especially transportation costs.
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, liners
of soil or admix materials may be cost-effective for lining some waste
disposal impoundments, provided they meet the technical requirements.
7.4 CASE STUDY METHODOLOGY FOR ANALYZING COST
To facilitate a deeper understanding of estimating the total cost of lined
disposal facilities, the "case study" analysis methodology has been selected
as the vehicle for estimating costs and to aid in liner selection. In case
study analysis, detailed construction drawings and specifications are neither
prepared nor desired. Instead, it is necessary only that a reasonably close
approximation of the size, location, type of construction, general layout and
costs of various components be developed and that this information be given in
sufficient detail to permit comparisons between alternative plans or with
established standards. Such a case study is presented in Appendix VI.
291
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292
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TABLE 7.2. COST ESTIMATES OF SOIL, ADMIX, AND. ASPHALT MEMBRANE LINERS
Liner type
Installed Cost
Dollars per square yard
1973a>° 1981
S i1 + bentonite
9 Ib/sq yd (1 psf)
Soil cement
6-in. thick + sealer (2 coats - each
0.25 gal/sq yd)
Soil asphalt
6-in. thick •*• sealer (2 coats - each
0.25 gal/sq yd)
Asphalt concrete, dense-graded paving
with sealer coat (hot mix, 4-in thick)
Asphalt concrete, hydraulic (hot mix,
4 in thick )
Bituminous seal (catalytically blown
asphalt) 1 gal/sq yd
Asphalt emulsion on mat (polypro-
pylene mat sprayed with asphalt
emulsi on)
$0.72
1.25
1.25
2.35 - 3.25
3.00 - 4.20
1.50 - 2.00
(with earth cover,'
1.26 - 1.37
$1.3;
2.27
2.27
5.00 - 7.00'
- 7.64<
1.73
- 3.64<
1.37 - 3.40C
aHaxo, 1976 (Octooer, 1973 costs).
^Estimated installed costs on west coast.
GCosts updated based on Engineering News Record data. Materials cost index
for October 1973 was 788.5. Materials cost index for November 1980 was
1433.7.
293
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CHAPTER 8
SELECTION OF A LINER MATERIAL FOR A WASTE DISPOSAL FACILITY
8.1 INTRODUCTION
The designer of a lined waste disposal facility is faced with making the
selection of a liner or liners which meet a wide range of requirements. This
chapter summarizes the approach that could be taken making that selection.
It is assumed that a basic decision has b^en made as to the site for the waste
disposal facility; however, there are factors in the soil and geology of the
site which must be known before the site selection can be made. Obviously,
the soil and geology at one site would be preferaole to another from the
standpoint of impoundment requirements. In making a decision regarding
the selection, it is necessary t:o consider the liner as a part of a many-
layered system of different permeaoi1ities and characteristics. These layers
extend from the waste itself and tne waste fluid through the liner and sub-
grade, the soil base and finally the aquifer. The principal factors can be
enumerated as follows:
- Type of waste and composition.
- Required operating life of disposal facility.
- Required life of the liner after closure of the facility.
- Soils on or nearby site, including subsoil.
- Hydrology and groundwater.
- Significant environmental factors.
- Acceptable flow out of impoundment.
- Permeability of available clay soil.
- Review of availab1? materials which appear to be potentially
compatible. •
- Compatibility tests of specific materials with sample of the waste
to be contained. .......
- Costs of principal candidate material and installation.
,294
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. Reliability of materials, seams, joints, etc. and document
experience in the technology.
8.2 THE FUNCTION OF THE WASTE DISPOSAL FACILITY
The first thing that must be known is the type of waste that is to be contaii
ed, whether it be a solid, liquid, sludge, etc. The type of waste wil
determine the general type of disposal site. Solid waste generally will <
into landfills, and liquid or partially liquid waste will be impounded i
ponds or lagoons. The character of the waste itself should be known as to it
chemical composition and whether there are components present that are highl
aggressive to the various types of lining materials.
The designer should know the anticipated life required of the impoundment.
landfill liner should last for extended periods of time. Many impoundment.
are either evaporating or holding ponds which may require only relative!.;
short periods of service. The selection of a liner can be greatly affected bj
the anticipated required service life.
Superimposed on these factors is the basic performance requirement that.will
be imposed by the various regulatory agencies. Together, these will form a
minimum performance requirement for the site.
8.3 CLAY SOIL ON SITE
It is important to know whether the soil on-site, or soil available from a
borrow pit nearby, can be used as a liner, or whether it should be used as
a subgrade for other type" of lining materials. From the cost standpoint,
soils are generally the least expensive, but they have a variety of limita-
tions.
In making the decision as to the suitability for the liner, the permeability
to water and to the waste fluid should ~e determined. Tests should be made as
to the structural strength of the soi.. If the soil does not have adequate
permeability or is sensitive to the waste, it still must be tested to deter-
mine its quality as a subgrade, where strength is a major factor.
8.4 HYDROLOGY
The groundwater level is an important factor in the siting of a waste disposal
facility, but it also should be evaluated and determined as a part of the
liner selection process as should the permeability of the in-place soil below
the faci.lity. The permeability of the native soil and its thickness can have
a significant bearing on the design of the soil liner, as discussed in Chapter
5 and Appendix VII. The flow of water within the aquifer also can be a factor
in the total system as there can be a dilution of any pollutant species that
might enter the aquifer.
8.5 SIGNIFICANT ENVIRONMENTAL FACTORS
The significant environmental factors include such items as prevailing winds,
temperature, rainfall, drainage, and the subsurface geology. It is important
295
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to know the overall geological cnaracter of the rocks, soil, depth of strata,
and the chemical and physical characteristics of the subgrade soils, clays,'
and rocks.
8.6 ACCEPTABLE FLOW THROUGH A LINER
Once the permeabilities have been obtained for the various layers that make UD
the impoundment system from waste to groundwater, one can calculate the
thickness of a liner of a given permeability to meet the basic flow require-
ments. It is possible, in making this calculation, that the specific soils
which were expected to be used will require too great a thickness to be
compacted properly. At this point, the decision may be that other lining
materials must be used.
8.7 REVIEW OF AVAILABLE MATERIALS
With the knowledge of the wasce that will be impounded and the level of
permeability required in the liner, a review should be made of those materials
which appear potentially suitable as liners. A screening of these materials
can be made based upon the state-of-the-art knowledge and a selection made of
those" which are potentially compatible with the waste fluid. Information in
this Manual and some of the references should be useful. Also, guidance can
be obtained from suppliers of lining materials.
8.8 COST OF LINER MATERIALS
A preliminary estimate can be made of the costs of the various lining ma-
terials such as found in Chapter 7. It is anticipated that several lining
materials may be suitable' for the lining of the soecific site and the selec-
tion can be based upon costs and other considerat1ons.
8.9 COMPATIBILITY TESTS
The principal candidates for the liner should be subjected to exposure tests
in direct contact with the waste. Compatibility tests for soils and membranes
are suggested in Appendix III. These tests should indicate the compatibil-
ity of the liner to long exposure with the wastes. Completely incompatible
combinations become obvious in relatively short times. However, due to low
concentration of aggressive constituents in a waste liquid, incompatibility of
some combinations may take months or even years Co show up. At the present
state-of-the-art, extended lives of many years have not been demonstrated in
actual service in waste disposal facilities; dependence must be placed on
accelerated testing to assess compatiblity and durability such as immersion
tests at room temperature and 50°C.
8.10 SELECTION OF LINER MATERIAL
In making the final selection of a liner material, some factors take prece-
dence over others. The principal fjnction of the liner is to impede the flow
of pollutants from the impoundment for the duration of its required life and
sometimes to form the barrier table on which the flow of a leachate can take
place for collection and treatment.
296
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Although there may be some variation in the priority of the factors, t>
following requirements must be met:
a. Compatibility and durability of the liner in the presence of tf
fluid to be contained.
b. Low permeability to the waste over extended periods of time.
c. Reliability and low risk of failure.
d. Relative ease of installation, quality control, repair, and mainte
nance.
The selection can also depend on cost if the above requirements are al'
met. Following the liner selection, the designer can proceed with th«
detailed design of the disposal facility as it relates to the liner. It is
recognized that more than one material may be selected in which case some
alternatives may have to be incorporated in the drawings and specifications.
297
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CHAPTER 9
SPECIFICATION FOR CONSTRUCTION OF LINED WASTE IMPOUNDMENTS
9.1 INTRODUCTION
After selecting the liner material and incorporating it into the design of the
waste disposal facility, the architect-designer-engineer must prepare the
necessary specifications and drawings for the bid package and for use in
the construction of the facility.
As in all engineering projects, the preparation of good specifications is
essential to obtaining satisfactory construction or to meeting the goals of
the project (Goldbloom and White, 1976). Incomplete drawings and specifica-
tions can result in high-price bids, construction uncertainties, and
inadequate product and performance. It is not possible to prepare adequate
performance specifications on a product such as a waste impoundment. Too many
uncertainties 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 upon accepted procedures
of construction, required values of the properties of the materials usectf
in the project, and quality control at all stages of construction. ™
9.2 SPECIFICATIONS FOR CONSTRUCTION
Following the procedures set forth in the specification should increase the
probability of meeting the project requirements and assuring an effective
waste disposal facility. These specifications should include specific in-
structions for the following:
- Site preparation, embankment, and other earthwork.
- Subgrade preparation.
- Drainage and gas venting systems.
- Appurtenances and penetrations.
- Liner construction for soil:;, admixes, sprayed-on materials.
- Liner installation, particularly field seaming.
- Quality control by the construction and 'installation contractors.
- Quality assurance by the owner or his representative.
Construction details are presented in Chapter 5. Table 9-1 lists references
which give examples of detailed procedures of the construction, various types
of liners, and includes subgrade earthwork and subgrade preparation.
298
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IuN PROCEDURES AND SPECIFICATION FOR LINERS
OF WASTE DISPOSAL FACILITIES
Preliminary3 List of Suggested References
Material
Installation of liner
SuDgrade and eartnwork
Clay soil
Admixes
Aspnalt concrete
Sol 1 cement
Bentonite-soil
Soil aspnalt
Portland cement
concrete
Flexible memoranes
Spray-on memoranes
Aspnalt
Modi fled asphalt
Airblowr. concrete
(shotcrete)
Bureau of Reclamation,
1974, p. 189; Bureau of
Reclamation, 1977, pp.
669-700.
Day, 1970, pp. 52-60;
Aspnalt Inst., 1976,
pp. 13-18; Aspnalt Inst.,
1975, 60 pp.
Day, 1970, pp. 60-64,
PCA, 1979.
Day, 1970, pp. 64-66
Amen can Col loid Co.
and Dowel 1 trade
1iterature.
Day, 1370, pp. 64-66.
Kays, 1977, pp. 124-131.
Day, 1970, pp. 46-57;
Bureau of Reclamation,
1974, pp. 176-184.
Day, 1970, pp. 46-47
Aspnalt Inst., 1976,
pp. 8-9.
Day, 1970, pp. 46-47,
Day, 1970, pp. 46-47
American Colloid Co.
and Dowel 1 trade
1iterature.
Day, 1970, pp. 46-47,
Water and Power Resources Water and Power Resources
Service0, 1980, pp. 4-1 to Serviceb, 1980, pp. 3-4 to
4-9; Day, 197U, pp. 47 tc
50; Appendix IX; Smal1,
1980; .Morrison et al ,
1982; manufacturers and
suppliers trade litera-
ture.
Aspnalt Inst., 1976,
pp. 19-20; Day, 1970,
pp. 50-51.
Chevron USA, 1978, pp.
7-9 and 13-15; Cnevron
USA, 1980, pp. 1-9.
Kays, 1977, pp. 131-136
3-6; Day, 1979, pp. 46-47.
Smal1, 1980; Morrison et
al, 1982; manufacturers and
suppliers trade literature.
aTo be expanded in revi
bName of the Bureau of
sions. - "
Reclamation from November 1979 to May 1981
299
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9.3 SPECIFICATIONS FOR LINER MATERIALS
In addition to the construction specifications, the liner materials must b«
controlled and tightly specified. The properties of the various lin
materials are described in Chapter 3 and their installation is described
Chapter 5.
The range of materials that fall under the category of polymeric materials,
as indicated in Chapter 3, is extensive and the technology is relatively
new. Specifications have been developed by polymer manufacturers, sheeting
and film manufacturers, and panel fabricators. The specifications thus have
emerged from the rubber, plastics, and textile techologies and have varied
considerably in requirements and in test methods. Although several test
methods may be used to assess the same property, e.g. tear strength, the shape
of the test specimens, rates of test, and temperatures of test can vary.
At the present: time, the number of generally accepted specifications for
lining materials is limited and those that are available are incomplete and
inadequate for use in the selection of liners for waste impoundments from
currently available materials. The liner industry has a variety of speci-
fications; each company has its own specifications and selected test methods
for its specific materials.
9.3.1. Current ASTM Specifications
Five ASTM specifications now exist for lining of canals, ponds, and re-
servoirs, four of wnich'pertain to polymeric membranes. These five speci-
fications are primarily designed for water impoundment and conveyance.
They cover the following materials:
1. Flexible poly(vinyl chloride) sheeting 'D3083-76, reapproved 1980).
2. Low-density polyethylene and ethylene copolymer plastic sheeting
(D3020-75, reapproved 1980).
3. Vulcanized outyl rubber, neoprene, and ethylene-propylene rubber
sheeting (03253-81).
4. Fabric-reinforced vulcanized butyl rubber, neoprene, and ethylene
propylene rubber sheetings (03254-81).
5. Prefabricated asphalt panels (02643-80).
The above specifications for the polymeric sheetings state in tne scope of
eacn that test methods and stancards should be used "to characterize the
sheetings and are intended to insure good workmansnip and quality. They are
not necessarily adequate for design purposes in view of the important en-
vironmental factors and specific performance objectives" (ASTM, 1982). They
state further that "tests have been selected with aqueous_ systems and combi-
nations of aqueous and hydrocarbon systems in mind. Other tests may be
necessary to establish chemical resistance and durability under the conditions
of a particular application".
The specific test methods included in the four specifications for polymeric
membrane liners can be grouped into the following categories:
300
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- Tests for analytical prope TVes and information regarding construe
tion and dimensions.
- Tests of the physical properties of unexposed sheetings.
- Tests for environmental and aging effects on the physical properties o
sheetings.
The test methods for a given property can differ considerably among tn
various membranes because of differences in material type, composition, an
construction. Table 9-2 shows the specific ASTM test methods that are use
in the ASTM specifications for flexible polymeric membranes. Table 9-
presents the physical requirements for each of the flexible membrane liners ii
the ASTM specifications. The materials are classified as to whether they an
fabric-reinforced or thermoplastic, crosslinked, or crystalline material;
without fabric reinforcement. As can be seen from these two taoles, som«
properties are not measured on all materials. Tests for environmental effects
and accelerated aging are limited principally with respect to exposure time,
e.g. the oven aging test is only run for seven days, the ozone test for sever
days, and the soil burial test for 30 days. No test is included for com-
patibility of candidate liner materials with the waste to be contained. As
indicated above, tnese tests are not adequate for tne selection of ,-natarials
for lining waste impoundments althougn, in most cases, they were adequate for
water impoundment and conveyance-applications.
The specifications are limited in scope of tne materials that they cover
and in some of the properties that are tested. They do, however, give an
indication of the amount of sampling that is required, althougn it appears to
be inadequate for small jobs. These specifications do not cover a wide range
of materials that are being manufactured and are being used in the lining of
waste storage and disposal impoundments, l-ose not covered in tne ASTM
specification include membranes of chlorinated polyethylene, chlorosulfonated
polyethylene, epi chl orohydri n ruober, .h i gn -oeos 1 ty polyethylene and the
various fabric-reinforced thermoplastic sneet:°gs. Among the significant
properties tnat are not included in tne test plan are peel tests of adhesion
of seams and tensile properties at somewhat elevated temperatures, and punc-
ture tests. They set no requirements for the seams prepared in the field
during installation. Requirements regarding such properties are desirable
in speci fications.
9.3.2 Standards Under Development for Flexible Polymeric
Membranes
The American Society of Agricultural Engineers has a-lso developed a specifi-
cation for flexible membrane linings (ASAE £P J4u.l, Installation of Flexible
Membrane Linings) for ponds, reservoirs, and canals. This specification
covers unreinforced butyl rubber/EPDM, fabric reinforced butyl rubber, poly-
ethylene (low density), and P'VC sheeting.
Several other standard-setting organizations have prepared or are preparing
specifications on polymeric lining materials, including:
American Society of Civil Engineers (ASCE).
American Water Works Association (AWWA).
301
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TAaLE 9-2. PROPERTIES AND ASTM TEST METHODS JSED IN ASTM MEMBRANE LINING SPECIFICATIONS*
Type of Tiemorane
Type of composition-1
Major polymer in compound1-
ASTM specification of limng
Analytical properties, con-
struction, and dimensions
Thickness
Polymer composition
Asn content
water extractaoles
Plasticizer volati 1 ity
(activated caroon)
Memorane without faonc reinforcement raor-c roinrnr/-a.*^B
T?
PVC
03083
0374
01755
01239
01203
X|_ ex
IIS, EPOM.CR LOPE
03253 03020
0412 0374/Metnod C
01273
na na
XL ^
IIS, EPOM, CR
93254
0751
na
Physical properties
Nomenclature
Conditioning
Tensile properties
Tensile strengtn
Elongation at oreaK
Stress at 3001 elongation
Strengtn of factory seams
'ear resistance
Hardness, Duro A
Compression set
•Hydrostatic ros's
Impact resistance
Luminous transmittance
Pinnoles and cracxs
Permeaoility arooert'es
Environmental and aging
effects
d< -c/ung
Oimensional cnange in
neating
drittleness temperature
effect or" liquids
«ater resistance
Ui I resistance
(i f requi red)
Air oven aging
Ozone resistance at 40*C
and in 50 ppnm Oj
flame resistance
(if required)
Soil ounal
Tensile strengtn cnange
Elongation .loss
0613
D882/*»tnod A
0882/Metnod A
03083/Sec. 9.3
08827^tnod A
- 010U4/01322*
33083
none
01146
01204
01790
01418
(d)
0412
0412
0412
03253/Sec.7.2
0624
02240
0395"
none
0618
0882/Metnod A
0882/Metnod A
01922
:)1709/Metnod 3
02103
03020
--ne
01418
(a)
0751(GraO)
0751(Grao)
03254/Sec. 7.2
0751(tongue tear1
na
01204
0746
0471
0471
0573
01149
(strip speciren at
201 elongation)
C542
none
na
01204
cTMS-191-5
0471
0471
0573
0513/Mtd i
(looped specimens;
01149
C542
D3083
0882
0882
aFor ponds, canals, and reservoirs.
DType of polymeric composition: TP » tnermoplastic, XL » vulcanized, CX » partially crystalline..
cMajor polymeric compound: PVC » poly(vinyl cnionde), IIR * Duty), EPOM » etnylene propylene ruooer,
CR * neoprene, LOPE » low density polyetnylene.
dln accordance witn individual test metnod in tne column.
eUse 01922 for film 8-16 mils and D1004 for sneetlng 16-30 mils., .
fFederal Test Method Standard.
302
-------
•»»L£ )•). ""51CAL »tr*jirs :i '•<(. >sr« s?sc:f; CAMPUS -'OK tum
Mjor aol/iwr 11 co«ooundc
Afl4(ydc*l ?rog«rtiti. construction,
*na dT«tftiion<
r*icin«»l (flMi"«l), *H$
folflfinct m I of s0«ctff«d cnici-
Asn conttflt, 1 (MI)
«4t«r titPKtJDltf , 1 (**»)
'lilttCUtf *oUClMCy, I !*4»)
(jct1*«t*a carton)
rtftiilf strtngcn, j»i ;*inf
itPMI *C JlXJl tlonqatlOI. 9»l (mm)
Strtflyt" 3f Mctory it 4*1 , I of
Tttr rtSMCanct iBf/tfl (*1")
HydPQItJCIC rflistjnct, 911 («1n)
'AUACt 9f (ll 1 *«0 )
Lj«
is-30 :o :o Jo
.7 -15, -iO -IS, -10 -15, -lO
.
0.3S
1.3 ...
2000 ::co JOG isoo
250 300 !OQ 2SO
500 )OU
jl) :n snt«r '.tit, 'allure should :axfl alact
;M snf in ic
««1ni«u« 3r«««i^9 urfi,jtn • i\ 50tn oirectioni • i J0u"a« 'Orel.
itjf-UH 'orct ;tr m I .
1*" JZllll. :-t :e«r -tflui f
'''ounni '3<-c«. Cor •.mciiiiitt a
Cion, 20 «ils, ) 'a/, 4S tnd 62
far
'^or atntr tftlc*nt«J«i :ftf «ininu« rtfluir
Jn«it it WC 'or 24 IOUM.
'»)r o««n 49119 'or 7 1 1C US'C.
'Oiinift IK »olu« <'ttr ;u n 4t !00*C M «S"« 10. 3 oil.
nir ov«n
-------
standards. At present (October 1982), final agreement with respect to tne
specific materials and tneir manufacturing requirements and properties nas
not been achieved.
9.3.3 Suggested Standards for Representative Flexible
Polymeric Membranes
In view of tne lack of accepted standards to cover currently available flexi-
ble membrane ;naterials for lining waste disposal impoundments, suggested
standards for representative membranes currently available (October 1982) are
presented in Appendix VIII using currently availaole data. Tney are based
largely on tne properties and tests listed in Table 3-7 in Chapter 3 and
reflect some of the current efforts to develop standards. The required
values are preliminary and subject to change.
These specifications should not be used to select materials. Selection, as
indicated in Chapter 8, should be based upon factors of compatibility with the
waste liquid, durability, etc. These specifications should be used as a means
of assuring tne quality of the lining material that is installed in the waste
disposal facility and of assuring that the quality of tne material is the same
as was observed in the compati011ity :ests. Not all tests are used for
quality control, e.g. burial exposure test, but instead set the requirements
for the quality of the selected material. For quality control purposes, it is
suggested that random samples oe taken from each 10,000 square yards of
sheeting; however, a minimum of five samples for quality control testing
should be taken f'-om each job. Each sample should be tnree by six feet and
should include a 'actory seam if the memorane requires factory fabrication.
These standards present values for different properties which can characterize'
membranes current:!/ on the market. By themselves, tney are not adequate to
predict product performance, and cannot be used for engineering design pur-
poses. For example, the low temperature resistance numbers represent qual-
ities measured after a few minutes exposure at a given temperature and snould
not be interpreted or extrapolated into installation temperatures and condi-
tions. 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.
As in tne case of the ASTM specifications, requirements have not been set for
several important properties because of the lack of data at this time. Of
particular importance are requirements relating to peel adhesion of seams,
puncture resistance and complete test properties of fabric-reinforced mem-
branes.
The industry is developing new materials and new products which, in the
future, the designer and engineer will be able to incorporate into their
designs for lined disposal facilities. As these materials are developed,
specifications will be set for use in impoundment construction and quality
control. They will be incorporated in future revisions of this Technical
Resource Document.
304
-------
REFERENCES
Chapter 9 - Specifications for Construction of Lined Waste Impoundments
The Asphalt Institute. 1975. Model Construction Specifications for Asphal
Concrete and Other Plant-Mix Types. 5th ed. (SS-1). College Park, MD
60 pp.
The Asphalt Institute. 1976. Asphalt in Hydraulics. (MS-12). College Park
MD. 65 pp.
ASTM Standards. 1982. Part 15. American Society for Testing and Materials
Philadelphia, PA:
D2643-80 Standard Specification for Prefabricated Asphalt Reservoi
Pond, Canal, and Oitcn Liner (Exposed Type).
03020-75 (Reapproved 1980) - Standard Specification for Polyethy-
lene and Ethylene Copolymer Plastic Sheeting for Pond$
Canal, and Reservoir Lining.
03083-76 (Reapproved 1980) - Flexible Poly (vinyl chloride)
Plastic Sheeting for Pond, Canal, and Reservoir Lining.
03253-81 Vulcanized Rubber Sheeting cor Pond, Canal, and Reservoir
Lini ng.
03254-81 Fabric-Reinforced, Vulcanized Rubber Sheeting for Pond,
Canal, and Reservoir Lining.
Bureau of Reclamation. 1964. Earth Manual, 2nd ed. U.S. Government Printing
Office, Washington DC. 810 pp.
Bureau of Reclamation. 1977. Design of Small Dams. 2nd ed. Revised reprint.
U.S. Government Printing Office, Washington, DC. 816 pp.
Chevron U.S.A., Inc. 1978. Chevron Industrial Membrane System Manual. As-
phalt Division, Chevron U.S.A., Inc. 56 pp.
Chevron U.S.A., Inc. 1980. "hevron Industrial Membrane for Earthen Reservoirs.
Construction Guide C--64P. Asphalt Div., Chevron U.S.A., Inc. 9 pp.
Day, M.E. 1970. Brine Disposal Pond .Manual. .Office of Solid Wa'Ste Contract No.
14-001-1306. Bureau of Reclamation, U.S. Department of the Interior,
Denver, CO. 134 pp.
305
-------
Day, M.E. 1970. Brine Disposal Pond Manual. Office of Solid Waste Contract No.
14-001-1306. Bureau of Reclamation, U.S. Department of the Interior
Denver, CO. 134 pp.
Goldbloom, J. and J. J. White. 1976. Specifications. In: Standard Handbook for
Civil Engineers. F. S. Merritt, ed., 2nd ed. McGraw Hill Book Co., NY.
pp. 3-1 - 3-23.
Kays, W.B. 1977. Construction of Linings for Reservoirs, Tanks, and Pollution
Control Facilities. Wiley-Interscience. 379 pp.
Morrison, W. R., E. W. Gray, Jr., D. B. Paul, and R. K. Frobel. 1982.
Installation of Flexible Memorane Lining in Mt. Elbert Forebay Reservoir.
REC-ERC-32-2. U. S. Department of tne Interior, Bureau of Reclamation.
pp 46.
PCA. 1975. Soil Cement Slope Protection for Embankments: Construction.
Publication IS167.02W. Portland Cement Association, Skokie, IL.
PCA. 1979. Soil Cement Construction Handbook. Portland Cement Association,
Skokie, IL. 41 pp.
PCA. a. Suggested Specifications for Soil Cement Linings for Lakes, Res-
ervoirs, Lagoons. Publication IS136.02W. Portland Cement Association,
Skokie, IL.
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 .'"eeting of Rubber Division,
American Chemical Society, Las Vegas, NV. John H. G-ifford Library,
Akron, OH.
Water and Power Resources Service. 1980. Specifications. Mt. Elbert Fore-
bay Reservoir - Membrane Lining. Frying Pan - Arkansas Project Colora-
do. No. DC-7418. U.S. Department of the Interior. Denver, CO.
Note: From November 1979 to May 1981, the Sureau of Reclamation was.
known as the Water and Power Resources Services.
306
-------
APPENDIX I
UNIFIED SOIL CLASSIFICATION SYSTEM
flfH i ri I
»a?3 i ;Ili
iJfM Hi*'?i
>;^_ ««:3Hf
55=5*
Hil$tf:;i.i"*J =
I
j< * > *^
307
-------
APPENDIX II
REPRESENTATIVE LIST OF ORGANIZATIONS IN LINER INDUSTRY
A. POLYMERIC MEMBRANE LINERS
1. Polymer producers
2. Manufacturers of polymeric membrane sheeting
3. Fabricators of liners
4. Installing contractors
8. 8ENTONITE PRODUCERS AND SUPP.IERS
C. OTHER LINER MATERIALS
D. MISCELLANEOUS ORGANIZATIONS IN THE LINER INDUSTRY
308
-------
A. PGLfMERIC MEMBRANE LINERS
1. Polymer Producers
DOW CHEMICAL COMPANY
2040 Dow Center
P.O. Box 1847
Midland, MI 48640
Contact: John L. Hartman
Product Sales Manager,
Chlorinated Polyethylene Design-
ed Products Department
Phone: 517-636-1000
MONSANTO INDUSTRIAL CHEMICALS CO
260 Springside Drive
Akron, OH 44313
Contact: Gary E. O'Connor
Project Manager
Commercial Development
Department
Rubber Chemicals Divis'
Phone: 216-666-4111
E.I. du PONT de NEMOURS AND CO.,
INC.
Elastomer Chemicals Dept.
Wilmington, DE 19898
Contact: Richard J. Arhart
Phone: 302-999-3160
PANTASOTE, INC.
26 Jefferson St.
Passaic, NJ 07055
Contact:
Phone:
Larry Kamp
201-777-8500
Contact: Gerald E. Fisher
3245 Sunnyside Ave.
Brookfield, IL 56513
Phone: 312-435-6381
E.I. du PONT de NEMOURS AND CO.,
INC.
Explosive Products Division
1007 Market Street
WiImington, DE 19898
Contact: Mr. T.J. Enright
Geotextile Product Manager
Phone: 302-774-1000
POLYSAR, LTD.
Technical Development Division
Vidal Street
Sarnia, Ontario
Canada N7T 7M2
Contact:
Phone:
Carl Hancock
519-337-3251
SHELL CHEMICAL COMPANY
605 N. Main Street
Altanont, IL 62411
Contact:
Phone:
Larry Watkins
618-483-6517
EXXON CHEMICAL CO.
Elastomer Technology Division
P.O. Box 45
Linden, NJ 07036
Contact:
Phone:
201-474-0100
UNIROYAL CHEMICAL COMPANY
Spencer Street
Naugatuck, CT 06488
Contact: Allen Crepeau
Phone: 203-723-3825
HERCULES INCORPORATED
910 Market St.
Wilmington, DE 19899
Contact: Norman C. MacArthur
Product Manager, Elastomers
Phone: 302-575-6293
309
-------
2. Manufacturers of Polymeric Membrane Sheetings
BURKE RUBBER COMPANY
2250 South Tenth St.
San Jose, CA 95112
Contact: D. Kutnewsky
Manager, Flexible Membranes
Phone: 408-297-3500
CARLISLE SYNTECH SYSTEMS
Division of Carlisle Corporation
P.O. Box 7000
Carlisle, PA 17013
Contact: William Witherow
Product Manager
Liners and Waterproofing
Phcne: 717-245-7000
COLUMBUS COATED FABRICS
1280 N. Grant St.
Columbus, OH 43216
Contact:
Phone:
Lee Fi shbein
614-225-6069
B. F. GOODRICH COMPANY
Engineered Rubber Products Division
500 S. Main Street
Akron, OH 44318
Contact: R. D. Cunningham,
Sales Manager,
Environmental Products
Phone: 216-379-2226
GUNDLE LINING SYSTEMS,
1340 East Richey Road
Houston, TX 77073
INC.
Contact: Richard K.
Phone: 713-443-8564
Schmidt, Preside
HARTE S COMPANY
10 Link Drive
Rockleigh, NJ 076-1660
Contact:
Phone:
R. H. Dickinson
201-767-1660
COOLEY, INC.
50 Esten Ave.
Pawtucket, RI
02862
Contact:
Phone:
Paul Eagleston
Vice President
401-724-9000
MAINLINE, INC.
3292 South Highway
Redmond, 3R 97756
97
Contact:
Phone:
DeWitt Maine
503-548-4207
GACO
P.O. Box 88698
Seattle, WA 98188
Contact:
Phone:
Earle Johnson
San Jose, CA
415-341-5661
310
-------
OXFORD, INC.
220 Rainbow Blvd. North
Niagara Falls, NY 14303
Contact:
Albert Hooper
Vice President
716-283-6900
PANTASOTE, INC.
26 Jefferson St.
Passaic, NJ 07055
Contact:
Larry Kamp
201-777-8500
PLYMOUTH RUBBER COMPANY
104 Revere Street
Canton, MA 02021
Contact:
Phone:
Charles Neese
617-328-0220
PROTECTIVE COATINGS,
1602 Birchwood Ave.
Ft. Wayne, IN 46803
INC.
Contact:
Phone:
Elmo Murrel1,
219-422-7503
President
SARNAFIL (U.S.), Inc.
Canton Commerce Center
Canton, MA 02021
Contact:
Phone:
Clark Gunness
617-828-5400
SHELTER-RITE, INC.
Division of Seaman Corp.
P.O. Box 331
Millersburg, OH 44654
Contact: Dr. Bala Venktaraman,
Vice President,
Research and Development
Phone: 216-674-2015
STEVENS ELASTOMERIC & PLASTICS
PRODUCTS, INC.
27 Payson Ave.
Easthampton, MA 01073
Contact: Arnold G. Peterson
Phone: 413-527-0700
TENNECO CHEMICALS, INC.
P.O. Box 189
Piscataway, NJ 08805
Contact: Bob Hayes/Kent Turner
Phone: • 201-356-2550
UNIROYAL, INC.
312 N. Hill St.
Mishawa
-------
3. Fabricators of Liners
ADVANCE CONSTRUCTION SPECIALTIES
P. 0. Box 17212
Memphis, TN 38117
Contact: H. M. VanNleuwenhuyze,
President
Phone: 901-362-0980
BROWN AND BROWN
P.O. Drawer 269
Mobile, AL 36601
Contact: Sam Brown, President
Phone: 205-479-6581
ELECTRA TARP, INC.
Park Centre
7241 Whlpple Ave. , N.W.
North Canton, .OH 44720
Contact: Bob Fulmer, President
Phone: 216-497-1496
ENVIRONETICS, INC.
9824 Industrial Drive
Bridgeview, IL 60455
Contact: Ray Winters, President
Phone: 312-585-6000
PALCO LININGS, INC.
7571 Santa Rita Circle
P.O. Box 919
Stanton, CA 90680
Contact:
Phone:
Richard Cain,
President
714-898-0867
POLY-PLASTICS
P.O. Sox 299
Springfield, OH
45501
Contact: Roland Harmer, President
Phone: 513-323-4625
M. PUTTERMAN & CO.
2221 West 43rd Street
Chicago, IL 60609
Contact: A., Berman, President
312-927-4120
REVERE PLASTICS
16 Industrial Avenue
Little Ferry, NJ 07643
Contact: Larry Smith, President
Phone: 201-641-0777
FABRICO MANUFACTURING CORP.
1-300 West Exchange Avenue
Chicago, IL 60609
Contact: Jay Sabath, Sales Manager-
Phone: 312-254-4211
SOUTHWEST CANVAS MFG. CO.
Oklahoma City, OK
Contact: Richard C. Nelson,
Manager
Phone: (405) 672-3355
MCKITTRICK MUD CO.
P.O. Box 3343
Bakersfleld, CA 93305
Contact: Bill Wheeler, President
Phone: 805-325-5013
312
-------
STAFF INDUSTRIES
240 Chene Street
Detroit, MI 48207
Contact: Charles £. Staff,
President
Phone: (313) 259-1820
(800) 526-1368
SYNFLEX INDUSTRIES, INC.
2004-750 Jervis Street
Vancouver, British Columbia
Canada V6E 2A9
Contact: Gerald W. Sal berg,
President
Phone: (604) 682-3621
WATERSAVER COMPANY, INC
5890 East 56th Avenue
Commerce City, CO
P. 0. Box 16465
Denver, CO 80216
Contact:
Phone:
Bill Slifer,
Vice President
303-623-4111
MANUFACTURERS WHO ALSO FABRICATE
Burke Rubber Company
Carlisle Tire and Rubber Co.
B. F. Goodrich
Schlegel Lining Technology, "Inc.
Gundle Lining Systems
4. Installing Contractors
CRESTLINE SUPPLY CORP.
2987 South 300 West
Salt Lake City, UT 84115
Contact:
Phone:
Guy Woodward
801-487-2233
GLOBE LININGS, INC.
1901 East Wardlow Road
Long 3each, CA 90807
Contact: Wi1li am Kays
Phone: 213-426-2587
213-636-6315
ENVIROCLEAR, INC.
P.O. Box 242
Falls Village, CT 06031
Contact: Don Thompson,'President
Phone: 212-997-0100
518-325-3332
GASTON CONTAINMENT SYSTEMS, INC.
1853 North Main Street
P.O. Box 1157
El Dorado,. KS 67042
Contact:
Phone:
John Saenz
316-321-5140
GULF SEAL CORPORATION
Suite 275
700 Regency Square Blvd.
Houston, TX 77036
Contact: Wi11iam J. Way
Vice President
General Manager
Phone: 713-782-9220
313
-------
KEY ENTERPRISES, INC.
P. 0. Box 6606
Odessa, TX 79760
Contact: Ken Stewart, President
Phone: 915-362-2368
THE THURSTON WALLACE CO.
5470 East Evans Ave.
Denver, CO 30222
Contact: Cliff Heller, Vice PresidW
Phone: 303-758-2232
MWM CONTRACTING CORP.
347 North Main Street
Mil ford, MI 48042
Contact:
Phone:
Joe McCullough
313-685-9350
313-685-1201
TRI STATE CONSTRUCTION
959 108th Avenue, N.E.
Belieview, WA 98004
Contact:
Phone:
Joe Agostino
206-455-2570
NATIONAL SEAL CO, INC.
7701 East Kellogg
Wichita, KS 67202
Contact:
Phone:
John W. Owen
316-681-1931
UNIT LINER CO
P. 0. Box 739
Shawnee, OK 74884
Contact: J. A. Hendershot,
President
Phone: 405-275-4600
-ACIFIC LININGS,
P.O. Drawer GGGG
Indio, CA 92201
INC.
Contact: John Blatt, President
Phone: 714-347-0828
PLASTI-STEEL, INC.
3588 West 13th Street
Vickers-KS3&T Suilding
Wichita, KS 67203
Contact: M. C. Green, President
Phone: 316-262-6861
FABRICATORS WHO ALSO INSTALL:
McKittrick Mud
Synflex Industries, rnc.
MANUFACTURERS WHO ALSO INSTALL:
B.F. Goodrich Company
Gundle L:iing Systems, Inc.
Schlegel Lining Technology, Inc.
STA-FLEX CORPORATION
16 Post Road
Greenland, NH 03840
Contact: Lou Peloquin
4917 New Ramsey Ct.
San Jose, CA 95136
Phone: 408-224-0604
314
-------
B. BENTONITE PRODUCERS AND SUPPLIERS
AMERICAN COLLOID COMPANY
5100 Suffield Court
Skokie, IL 60077
Contact: Nick Kesslering
Ryan F. McKendrick
Phone: 312-583-0400
ARCHER-DANIELS-MIDLAND
P.O. Box 15166
Commerce Station
Minneapolis, MN 55415
Contact:
Phone: 612-371-3400"
INTERNATIONAL MINERALS &
CHEMICAL CORP.
IMC FOUNDRY PRODUCTS
17350 Ryan Road
Detroit, MI 48212
Contact:
Phone:
G. Alther
313-368-6000
CHARLES PFIZER & CO.
235 East 42nd Street
New York, NY 10017
Contact:
Phone:
212-573-2323
ASHLAND CHEMICAL
9450 Midwest Avenue
Cleveland, OH 44125
Contact:
Phone:' 216-587-2230
DOWELL
1150 North Utica Street
P. 0. Box 21
Tulsa, OK 74102
Contact: Chris Parks
Mining and Construction
Technical Services
Phone: 918-560-2972
WILBUR ELLIS CO.
P.O. Box 1286
Fresno, CA 93715
Contact:
Phone:
209-226-1934
WYO-BEN PRODUCTS, INC.
P.O. Box 1979
Billings, MT 59103
Contact:
Phone:
406-252-6351
DRESSER MINERALS
P.O. Sox 6504
Houston, TX 77005
Contact:
Phone: 713-972-2670
315
-------
C. OTHER LINER .MATERIALS
ARIZONA 'REFINING COMPANY
P.O. Box 1453
P*oenix, AZ 35001
Contact: J. R. Bagley, President
Phone: 602-258-4843
PHILLIPS PETROLEUM COMPANY
Commercial Development Division
Bart lesvi lie, OK 74004
Contact:
Phone:
Floyd H. Holland
918-661-6428
THE ASPHALT- INSTITUTE
Asphalt Institute Building
College Park, MD 20740
Contact:
Phone: 301-277-2458
PORTLAND CEMENT ASSOCIATION
Old Orchard Road
Skokie, IL 60076
Contact:
Phone
312-066-6200
CHEVRON, USA, INC.
Asphalt Division
P. 0. Box 7643
San Francisco, CA 94120
Contact: Kenneth Coleman
K. 0. Coleman Co
P. 0. Box 414
Santa Clara, CA 95052
Phone: 408-244-8948
I.U. MANAGEMENT SYSTEMS, INC.
1500 Walnut Street
Philadelphia, PA 19102
Contact :
Phone: 215-985-660
MICHELLE CORPORATION
Division of Weychem Canada Limited
P. 0. Box 4794
Charleston Heights, SC 29405
Contact: F. Weyrich, President
Phone: 803-554-4033
316
-------
D. MISCELLANEOUS ORGANIZATIONS IN LINER INDUSTRY
HOVATER-WAY ENGINEERS, INC.
23011 MouHon Parkway, Suite F-5
Laguna Hills, CA 92653
Contact: Louis R. Hovater
Phone: 714-830-4050
Type of service: Design engine-
ering, specializing in membrane
liners.
NATIONAL SANITATION FOUNDATION
NSF Building
Ann Arbor, MI 48105
Contact: Gary W. Sherlaw, D1rec:o
Standard Development
Phone: 313-769-8010
Type of service: Developing nation;
specifications for membrane liners,
INQUIP ASSOCIATES, INC.
P.O. Box 2182
Santa Barbara, CA 93120
Contact:
Phone:
U.E. Hensgen
805-963-6785
Type of service: Consulting, en-
gineering, and contracting of
various lining materials and.
slurry cut-off walIs.
LINING MATERIALS
23011 Moulton Parkway, Suite F-4
Laguna Hills, CA 92653
Contact: George J. Miller,
General Manager
Phone: 714-581-9292
Type of service: Supplier of a variety
of 1 i ni ng material s.
LIQUID CONTAINMENT SYSTEMS
P. 0. Box 324
South Holland, IL 60473
Contact: Jack Moreland, President
Phone: 312-468-2500
Type of service: Design, planning,
engineering, and installation of
liners.
317
-------
APPENDIX III-A
IMMERSION TEST OF MEMBRANE LINER MATERIALS
FOR COMPATIBILITY WITH WASTES
(Matrecon Test Method 3 - August 1981)
This test is designed to assess, under accelerated conditions, the compati-
bility of polymeric membrane liner materials with specific wastes.
Summary of Method
Samples of the polymeric liner materials are fully immersed in a repre-
sentative sample of the waste ~o be contained. Over a range of exposure
periods, tests are- run to determine the change in weight, dimensions, com-
position, and physical properties of the lining material as a function of
time. One immersion sample is required for each immersion time or exposure
condition.
Applicable Documents
- ASTM 0297, "Rubber Products; - Chemical Analysis". '
- ASTM 0412, "Rubber Properties in Tension".
- ASTM 0624, "Rubber Property - Tear Resistance".
- ASTM 0638, "Tensile Properties of Plastics".
- ASTM 01004, "Initial Tear Resistance of Plastic Film and Sheeting".
- ASTM 02240, "Rubber Property - Durometer Hardness".
-ASTM 03421, "Extraction and Analysis of Plasticizer Mixtures from
Vinyl Chloride Plastics".
- FTMS 101B, Method 2065, "Puncture Resistance and Elongation Test (1/8
inch Radius Probe Method)".
-Matrecon Test Method 1, "Procedure for Determination of the Volatiles
of Unexposed Membrane Liner Materials".
- Matrecon Test Method 2, "Procedure for Determination of the Extractable
Content of Unexposed Membrane Lining Materials".
318 I
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Equipment and Supplies:
Equipment:
- Exposure tank - minimum one gallon or four litre capacity, with prov
sion for hanging specimens so that they do not touch bottom or sides <
tank, or each other. Suggested arrangements are glass rods aero:
top of tank, or stainless steel hooks fastened to tank lid.
- Stress-strain machine suitable for measuring tensile strength,tea
resistance and puncture resistance.
- Jig for testing puncture resistance for use with FTMS 101B, Method 206
- Oven at 105±2°C.
- Dial micrometer.
- Analytical balance.
- Apparatus for running extractables, e.g. Soxhlet extractor or ASTM D29/
rubber extraction apparatus.
Supplies:
- Labels and hangers for specimens, of materials known to be resistant to
the specific waste. Hangers of stainless steel wire and tags made of
50 mil polypropylene, embossed with machinist's numbering dies and
fastened with stainless steel wire, are resistant to most wastes.
Procedure
1. Obtain representative sample of the wast1? fluid. Note if fluid clas-
sifies or separates.
2. Perform the following tests on unexposed samples of the polymeric
membrane liner materials:
2.1. Percent vola'tiles, Matrecon Test Method 1 (Appendix
III-O).
2.2. Percent extractables with suitable solvent, Matrecon Test
Method 2 (Appendix III-E).
2.3. Tear resistance, machine and transverse directions, five
specimens each direction. See Table III-A-1 for appropriate
test method and recommended speed of test.
2.4. Puncture resistance, five specimens, FTMS 1018, Method
2065.
2.5. Tensile properties, machine and transverse directions, five
319
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wo
w
G
L
0
LO-
Figure III-A-1. Die for Goodyear dumbbell having the following dimensions:
5.
W - Width of narrow section
L - Length of narrow section
WO - Width overal 1
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
Goodyear dumboells (Figure III-A-1) each direction. See
Table III-A-1 for appropriate test method, recommended test
specimen, speed of test, and values to be reported.
2.6.
Hardness, Ouro A
80), ASTM D2240.
(Duro D if Duro A reading is greater
Cut a 6 x 8 inch piece of the lining material for each waste and each
exposure period. Measure the following:
3.1. Gage thickness, mil or mm - average of the four corners.
3.2. Mass, g - to one-hundreth of a gram.
3.3. Length, cm - average of the lengths of the two sides.
3.4. Width, cm - average of the widths of the two ends.
Label the test specimen with a plastic identification tag and hang in
sample of the waste fluid by a wire hanger.
Note: In cases where the waste fluid is expected to stratify,
the number of immersed specimens per exposure period can be
increased so that test specimens exposed at each level of the
waste can be tested.
At the end of the exposure, remove specimen from waste. Wipe off as
much waste as possible and rinse well-with water. Place wet specimen
in a labelled polyethylene bag to prevent the specimen from drying
out.
320
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TEAR RESISTANCE
TEST SPECIMEN
VOLATILES
TENSILE DUMBBELL
i •
GRAIN DIRECTION
PUNCTURE RESISTANCE
.TEST SPECIMEN
figure III-A-2.
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— £ II
— w S.
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= o
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322
-------
6. To test the immersed sample, remove wire hangers and identificati
label from specimen. Wipe off any remaining waste and rinse wi
deionized water. Blot specimen dry and measure the followim
6.1. Thickness, mil or mm.
6.2. Mass, g.
6.3. Length, cm.
6.4. Width, cm.
The specimen should be returned to its polyethylene bag as soon a
possible to prevent any loss of absorbed water.
7. Perform the following tests on the exposed specimen:
7.1. Percent volatiles, Matr?con Test Method 7 (Appendix III-F)
7.2. Percent extractables, Matrecon Test Method 7 (Appendi
III-F).
7.3. Tear resistance, machine and transverse directions, twi
specimens each direction. See Table III-A-1 for approp-
riate test method and recommended speed of test.
7.4. Puncture resistance, two specimens, FTMS 1013, Methot
2065.
7.5. Tensile tests, machine and transverse directions, three
specimens each direction. See Table III-A-1 for approp-
riate test method, the recommended test specimen and speed
of test, and the values to be reported.
7.6. Hardness, Duro A (Duro D if Duro A reading is greater
than 30), ASTM D2240.
See Figure III-A-2 for a suggested cutting pattern.
8. Summarize the results as follows:
8.1. Percent change in thickness.
8.2. Percent change in mass.
8.3. Percent change in area.
8.4. Percent volatiles of unexposed and exposed liner material.
8.5. Percent extractables of unexposed and exposed liner
material.
8.6. Percent retention of physical properties.
8.7. Change, in points, of hardness reading.
9. Tests should be run over a range of exposure times. For compatiblity
studies, the suggested range of exposure times is 0.5, 1, 2, and 4
months to five years.
10. Fresh waste fluid may be required to maintain concentration of
constituents or to simulate actual service conditions.
323 I
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APPENDIX 111-8
TUB TEST OF POLYMERIC MEMBRANE LINERS
The purpose of the tub test is to evaluate flexible membrane liner materials
under conditions which simulate those that occur in actual service.
The effects of exposure to sun, temperature changes, ozone, and other weather
factors can be evaluated, as well as the effect of a given waste on a specific
liner. The fluctuation of the level of the waste is particularly significant
in that an area of the liner is subjected to both the effects of the waste
and weather. This alternating of conditions is especially harsh on liner
materials and is usually encountered in the field.
Equipment and Supplies:
- Plywood to construct tubs and catch basin
- Pipe fittings and corks for tub and catch basin drains and plugs
- Meter stick or similar device to measure waste depth
- Thermometers
- pH meter
- Conductivi ty meter
- Drying .oven
- Analytical balance
- Other equipment for chemical analyses, as needed.
Test specimen:
Piece of membrane liner, incorporating a field seam, large enough to fold 'er
edges of the tub. Approximate size four feet by four feet.
* *
Test Procedure:
The plywood tubs should be rectangular with sides sloping outward at a 1:2
slope. The dimensions of the tubs should be roughly 14" x 9" at the base,
25" x 20" at the top, and ca. 11" deep. Useful catch basin dimensions are
8 ft x 6 ft x 4 in (Figure III-8-1).
The liner specimen is draped over a tub and folded to fit the inside contours
and edges of the tubs. The excess material is allowed to hang freely over the
edges of the tub.
324
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Figure III-8-1. The open exposure tubs lined with polymeric membranes and
partially filled with hazardous wastes. They are covered
with chicken wire and placed in a shallow basin lined with an
elasticized polyolefin membrane. During rainy weather these
cells are protected by a corrugated plastic cover (Haxo
and White, 1977).
The tubs are filled from 3/4 to 7/8 full with wastes. The liquid level is
allowed to fluctuate about 4 inches. During the exposure period the tub
liners are inspected visually for cracking, opening of seams, and other forms
of liner deterioration. The waste levels and temperatures are measured and
recorded at regular intervals. Water is added when levels become too low.
An oily waste which generally has a film of water at the surface tends to
accumulate water (from dew) which does not evaporate significantly. Water,
or actually an oil-water mixture, should be pumped from the bottom of these
tubs to maintain liquid levels and prevent overflows of the waste. The
oil-water mixture removed may be analyzed for pH, electrical conductivity,
percent solids, and other parameters as appropriate. The water in the catch
basin is also monitored for pH and conductivity as a possible indication of
leakage from the tubs containing highly acidic or highly alkaline wastes.
Status of Tub Exposure Tests Underway in Oakland, California:
Long-term tub exposure tests on a roof in Oakland, California, were started
in November, 1976 (Haxo et al, 1977). As of April 1980, only one of the 12
325
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liner specimens that were placed in this test had Tailed. The tests consiste
of 12 tubs utilizing four wastes (spent caustic, alkaline slop water, nitri
acid waste, and a waste oil) and nine liner materials (elasticized polyolefin
two PVC's, polyester elastomer, butyl rubber, neoprene, EPOM, CSPE, and CP
Most of the liners have swelled to some degree after an exposure period
approximately 3.5 years.
The elasticized polyolefin exposed to the waste oil developed cracks ana
leaked on the 517th day of exposure. This liner was observed to have swelled
after one month of exposure arid the swelling apparently continued at a very
slow rate until failure. The elasticized polyolefin membrane developed in the
waste/sun interface area, two openings which were oriented alqng folds in the
membrane.
On removal from the tub, physical tests of the exposed liner were run at four
exposure locations:
- Under waste only
- In waste/shade zone
- In shade only
- In waste/sunlight zone
The waste/sunlight zone provided the harshest environment for the li
material, as shown by the test results in Table III-8-1.
ner
No other liner failure had occurred to April 1980, though deterioration of
the exposed liners was evident. The seams in the EPDM liner exposed to nitric
acid wastes had weakened and the caulking appeared cracked, but no leaking had
been detected. The PVC liner Delow the acid waste has become hard.- The
liners tended to swell more at folds as well as in the waste/sun zone,|
indicating that both situations should be regularly examined on in-service"
liners. At the sharp corners, the butyl rubber liner was ozone cracking.
TABLE riI-8-1. FAILED ELASTICIZEH ^LYOLEFIN LINER
EXPOSED TO SATURATED AND UiNSATURATED OILS IN OPEN TUBa
*
Test
Thickness, mi Is
Tensi le strength, psi
Elongation at break, %
Tensile set, %
S-100, psi
S-200, psi
Puncture resistance, Ib.
Elongation, inches
Original
value
23
2590
£65
445
875
970
26.3
0.97
% Retent
Waste
only
113
47
89
76
68
64
97
130^
ion of prooerty of exposure to
Waste •»•
sun
113
38
81
72
59
46
73
122
Waste +
shade
113
45
83
74
65
63
70
113
Shade
only
98
97
99
100
110
107
135
142
Exposure time: 506 days from 11/2/76 to 3/23/78.
326
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APPENDIX III-C
TEST METHOD FOR THE PERMEABILITY OF COMPACTED CLAY SOILS
Constant Elevated Pressure Methods
INTRODUCTION
To assess the suitability of compacted clay soils for the lining of waste stora<
facilities, the primary laboratory measurement is saturated hydraulic conducti*
ity or permeability. Such a measurement should be made on a specimen of soi
that has been remolded and compacted in the range of optimum moisture center
to achieve the maximum density possible for a given compactive effort. AST
Methods D698-73 or 01557-78 should be used for determining a soil moisture
density relation.
Testing procedures recommended in subsequent paragraphs are not suitable for
determination of field permeaoility values. They are, however, considered
suitable for performing comparative studies to evaluate the potential in-
fluence of waste leachates on permeability of compacted clay soils that are
candidates for use as liners. As a large variety of waste liquids are placed
in hazardous waste landfills and surface impoundments (Chapter 2), there is a
great need for a specific permeability test that can determine, in reasonable
lengths of time, the potential effects these 'eachates may exert on perme-
abi1ity of clay 1iners.
In the selection of soils for lining a specific impoundment, the candidate
soil or soils should be tested with the standard aqueous permeant and with a
representative sample of the waste liquid to be impounded. The results will
rank the soil-waste combinations and thus allow the choice of the most favor-
able soil for lining the facility.
The testing procedure is designed to reveal changes in permeability of
the compacted soil specimen when the native soil solution (pore water) is
replaced by the primary and/or secondary permeant. As a simulated native soil
pore liquid, we recommend a 0.01 normal aqueous solution of calcium sulphate.
The permeameter used in this test (Figure III-C-1) is constructed from readily
available and easily modified components. Standard compaction permeameters
and the necessary ASTM procedures are available through most soil testing
supply companies. All components in Figure III-C-1 are in common with the
standard permeameter except for the enlarged liquid chamber, extended studs,
high pressure fittings, Teflon outlet tubing, and Teflon gaskets. Figure
III-C-2 is a schematic of a test setup utilizing permeameters.
327
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INPUT
-PCTMEAM6TER
8ASC
•POBOU3 STONE
OUTLET—' t—TEFLON TUBING
Figure III-C-1. Schematic of the compaction permeameter (Anderson et
al, 1982).
AH TCKT CCXX^O CHAMBER
Figure III-C-2.
Schematic of the compaction permeameter test apparatus
(Anderson et al ,1982).
328
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Compacted clay soils often have water permeability values lower than 10"^ 01
sec~l and it may be necessary to pass one pore volume of standard calciun
sulphate permeant through a soil before a stable baseline permeability
value is obtained. After establishing the permeability baseline, the passage
of at least one pore volume of waste liquid may be necessary to determine
fully the effects that the waste liquid may have on permeability of the
compacted clay soil specimen. A pressurized air source should be used to
increase the hydraulic gradient and thus reduce testing time (Bennett, 1966;
Jones, 1960).
The use of large hydraulic gradients has shortcomings. The thickness of
immobilized fluid films on soil particles may be substantially decreased at
large pressures (Yong and Wartkentin, 1975). This would increase effective
pore diameter available for liquid flow and thus increase permeability. Also,
large hydraulic gradients can increase soil particle migration causing soil
clogging and a resulting decrease in permeability (Olson and Daniel, 1979).
Criteria for selecting an appropriate hydraulic gradient depends greatly
on proposed use of the permeability study. Where the objective is to estimate
field permeability val'ues, it has been suggested "to use gradients as close
as those encountered in the field as is economically feasible" (Olson and
Daniel, 1979). Zimmie (1981) suggested use of hydraulic gradients between 6
and 20 for laboratory studies attempting to duplicate field conditions.
In comparative permeability studies, larger hydraulic gradients are probably
acceptable; however, care should be taken to monitor particle migration.
Variations in permeant liquids may drastically change the permeability of a
given soil (Michaels and Lin, 1954).
Comparative permeability studies use multiple peneameters to isolate effects
of one or more variables. This testing aporoach has been widely used
in agricultural irrigation "studies evaluating tne influence of various salt
types and concentrations on soils of low permeability (Mclntyre et al, 1979;
McNeal, 1974). Comparative methods have also been used to evaluate the
influence of organic liquids on soils (Michaels and Lin, 1954; Van Schaik,
1970).
In comparative permeability studies, flow should be laminar, and all but the
variable being tested should be held constant. Under these conditions, any
change in permeability can be interpreted as being the result of changes in
the porous matrix. Soil permeability measurements must be carefully taken if
they are to be accurate. Leaks, volatile losses, or channel flow along the
interface of the permeameter and soil will greatly affect permeability values
(Bowles, 1978).
Several authorities on permeability studies have expressed doubts that labor-
atory permeability tests are capable or reproducing field conditions. Olson
and Daniel (1979) noted that the volume of, soil samples used in laboratory
tests is almost always too small to contain'statistical ly significant distri-
butions of macrofeatures encountered in the field (i.e. sand lenses, fis-
sures, joints, channels, root holes, etc). They further noted that, samples
329
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taken in the field may be affected either by the sampling method or selectio
of the most uniform or intact sample. Bowles (1978) stated that "the soil^
the permeability device is never in the same state as in the field; itW
always disturbed to some extent". Zimmie et al (1981) stated "it is virtual 1j
impossible to duplicate field hydraulic gradients in the laboratory. Tes"
times become excessive and it becomes difficult to obtain accurate measure-
ments of flows and heads at very low hydraulic gradients."
Several factors not incorporated into laboratory tests affect overall permea-
bility of clay. Sherard and Decker (1977) listed primary factors determining
"effective overall permeabiity" of a soil layer as being continuity, regu-
larity, thickness, and characteristics of interbedded layers or lenses.
Laboratory permeability determination on clay liners cannot account for this
type of variability and can only attempt to characterize a homogeneous sample
of clay soil. Other factors that may lead to discrepancies between field and
laboratory permeability values are discussed in detail by Olson and Daniel
(1979).
In the test procedure presented in this appendix, the following form of
Darcy's Law may be used:
K = AtTT
where:
K = Permeability (cm s~*)
V - Volume of liquid passed through the soil (cnr) (
A = Cross-sectional area of liquid flow (cm^)
H = Hydraulic gradient =
•
h = Hydraulic head (expressed as cm of water)
1 = Thickness of soil specimen (cm).
t = Permeation time (second).
Permeability values are plotted along the Y-axis, while the cumulative number
of pore volumes are plotted along the X-axis. The number of pore volumes is
obtained by dividing the total volume of leachate (V) by the pore volume of
the compacted soil specimen used in the test. (For an example plot, see
Figures 4-1 to 4-9 in Chapter 4.)
If there is a failure in the clay liner being tested, a rough estimate of the
time to failure of the real liner can be made by rearranging Darcy's law so
that time is isolated as follows: .. - •-
330
-------
" AHK
Assuming, for example, that a sharp permeability increase was recorded und
H = HQ at t = tQ and estimating the highest possible gradient in the fie
equal' to Hf (where Hf «HQ), the failure time of the soil liner, tf, will
given by: H
tf " t0 J.
Hf
One should emphasize that this is not an analysis of the failure time, bt
only a rough estimate of it.
It is important to obtain a permeability value and time incremen-t on each por
volume of leachate passed during a test. Failure to do so will make i
impossible to plot permeability vs pore volume or to perform a "time failure
calculation for the clay soil liner.
EQUIPMENT
1. Soil crusher (C-2 Laboratory Crusher).
2. Soil grinder (Hewitt Soil Grinder).
3. 2 mm sieve (CB-310 Brass Sieves).
4. Moisture cans (LT-30 Tin Sample Boxes).
5. Balance capable of weighing 20 kg. (L-500 Heavy Duty Balance),
6. Drying oven (105°C) to determine water content of soil samples.
7. Compaction molds (CN-405 Standard Compaction Mold).
8. Compaction hammer (CN-4230 Mechanical Compactor).
9. Steel straight edge.
10. Permeameter bases and top plates (K-611 Permeameter Adapter).
11. A source of compressed air with a water trap, regulator and pressure
meter.
12. A fraction collector with automatic timer for collection of samples
over time (Brinkman Linear II Fraction Collector with a multiple
distribution head).
13. An air tight, cooled chamber to limit volatile loss of samples during
and after sampling.
14. A vented hood to hold the compaction permeameters and chamber con-
taining the-fraction collector. (This is a safety precaution to limit
exposure of laboratory personnel to the hazardous chemicals used in
the studies.)
Note: Equipment in Items 1, 3, 4, 5, 7, 8; and 10 can be obtained from Soil
Test, Inc.; equipment in Item 2 can obtained from B. Hewitt Welding
and Repair.
331 i
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PROCEDURES
1. Obtain sufficient clay soil (ca 30 kg dry weight) to be tested
Approximately 3 kg dry weight of soil material is needed per com-
paction mold. Break the soil down to golf ball-sized clods and allo*
it to air dry.
2. Throughly break up the aggregation of the air dried soil and pass it
through an ASTM No. 4 (4.75 mm) sieve. Where refined clay products
are to be admixed with a native soil, thoroughly mix the materials
at this point. To improve the reproductibility of a mixture, proper
proportions should be determined using percentage by oven dry weight.
Do not oven dry the actual materials to be blended as this could
alter chemical and physical properties of the liner material.
3. After thoroughly mixing, the soil should be placed in air tight
containers and stored at room temperature until the time of test.
4. Determine the moisture density relations of the soil on five to seven
specimens using ASTM Method 0698-78 or 01557-78.
5. Use the remaining soil to prepare compaction molds at optimum mois-
ture content. Weign all compaction molds before and after placement
of the soil material to permit the determination of the bulk density,
porosity, and pore volume of each specimen.
6. Fit a valve on top of the permeameter too plate with pressure fit-
tings and connect it to a source of a 1 r pressure via copper tubing.
Place a water trap, pressure regulator, and pressure gage in line
between the air pressure source and permeameter. The water trap
should be placed between the pressure source and regulator to prevent
buildup of deoris en the membrane in t.ie regulator. The pressure
gage should be loaded between the regulator and a pressure manifold
to the permeameters so that the hydraulic head being exerted on the
clay soils can be monitored. Permeameters used for testing of clay
liners must be capable of safely operating with hazardous materials
including industrial solvents, volatile compounds, corrosive acids,
and strong bases. All gaskets used in permeameters should be Teflon
to prevent deterioration and possible blowout from contact with these
aggressive permeant liquids. To avoid leakage around the hard Teflon
gaskets, all metal surfaces against which the gaskets seat should be
•wiped clean of grit. Permeameter components have been found to
withstand continous operational use at pressures up to 60 psi.
Volatile' losses may occur during sample delivery from the outlet
tubing to the leachate collection bottles. To limit these volatile
losses, the top of each leachate collection bottle should be fitted
with a long stem funnel and- placed -in-an air-tight cooled compart-
ment. When volatile hazardous chemicals are used, the entire test
apparatus should be set in a vented hood.
332
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7. Place the standard permeant (0.01N CaS04) in the chamber above tl
compacted soil. To avoid channel formation, clay should be allow*
to seat at low pressure. By allowing standard permeant to stand c
the soil for 24 hours, an effective seat is obtained for the top f«
millimeters of the clay core. This thin layer will minimize tf
possibility of bulk flow along the permeameter sidewalls. The res
of the specimen should adequately seal when the permeant is forc<=
into the compacted soil specimen at elevated pressures. With severa
specimens producing leachate, it may be desirable to have an auto
matic fraction collector. This is especially useful with long-ter
tests.
8. To limit the volume for diffusive mixing of leachate samples afte
they have passed through a compacted specimen, the leachate outle
should be fitted with an adapter to 3 mm (inside diameter) Tefloi
tubing. The use of translucent Teflon at the permeameter outle'
provides a convenient window through which to monitor the expulsioi
of entrapped air. Standard permeant should be passed through th<
permeameter until no air bubbles are visible in the outlet tubing.
If soil piping occurs, eluted soil clays will be visible either
clinging to the inside walls of the outlet tubing or as a suspensior
in the collected samples. The liquid chamber should be completely
filled, and a constant pressure applied tnrough the pressure input
(10 psi should be sufficient to reduce testing time and minimize
particle migration in the soil). This constant pressure should be
maintained until no air bubbles are visible in the outlet tubing and
a constant permeability value is obtained. If the constant (equi-
librium) permeability values are not consistently below 1 x 10~/ cm
sec , the soi1 is probably not suitable as a liner material.
9. Oepressurize the permeameter and remove the top plate and liquid
chamber. If the soil has shrunk, it is probably not suitable as a
1iner material .
10, If the soil has expanded into the liquid chamber, remove the'excess
soil with a straight edge without smearing the soil surface, collect
all the removed soil material and ootain its oven dry weight to
permit recalculating bulk density, porosity, and pore volume of the
soil specimen. If the soil surface is smeared during the removal of
the excess soil, pass standard leachate to assure that the Permea-
bility has not been altered.
11. Place the waste permeant in the liquid chambers of the permeameters
and repressurize the system. Maintain at least two permeameters with
standard permeant for the duration of the tests. Where both a
primary and secondary leachate are expected to be generated by the
waste, each waste liquid should be used on at least two permeameters.
To collect the primary leachate, fill" a large Buchner funnel with the
waste and subject it to sufficient suction to extract the liquids
present in the waste. Repeat this procedure until approximately
333
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two liters of primary leachate (per permeameter) has been generated
Secondary leachate should be generated by the standard EPA procedu
agreed upon at the tine of test. For example, shake 5 kg of was
with 2.5 liters of water (per permeameter). The resulting solution
can be filtered using a large Buchner funnel.
12. Pass at least one pore volume of the appropriate permeant through
the soil specimen. If the specimen exhibits a trend of increasing
permeability, pass an additional pore volume of the leachate through
the soil. If the soil specimen maintains a permeability below
1 x 10"' cm sec"* and exhibits a decreasing or stable permeab-
ility after passage of the first pore volume, the permeameter
should be disassembled Co examine the soil specimen.
13. If the soil specimen has shrunk, it is unlikely to be suitable as a
liner material.
14. If the soil specimen has expanded, repeat the above procedures
beginning with Step 10.
15. If the soil specimen ha:; not. changed volume, reassemble the perme-
ameter and place the standard permeant (0.01N CaSC^) in the liquid
chamber,, Pass additional standard permeant. If the permeability of
the soil has consistently stayed below 1 x 10"' cm sec"1 as measured
with the standard, primary, and secondary leachate, proceed to Step
16.
16. Examine the translucent Teflon outlet tuning for signs of particle
migration out of the soil specimen. If there i-s evidence of soil
migration, pass an additional standard oermeant to observe if the
internal erosion continues. If it con:inues, the soil probably
will not; be suitable for use as a Hner material. If the soil
migration stops, proceed to Step 17.
17. Depressurize the system and extrude the soil specimen from the
compaction mold to examine it for signs of cracking, internal
erosion or soil piping, dissolution, structural changes, or any other
difference from the soil specimens that received only standard
leachate. If there are none of the above signs that the soil has
deteriorated due to contact with the waste leachate, the soil should
be suitable as a liner material to contain that particular waste.
Comments
This procedure is designed to reveal changes in flow properties due to the
replacement of the soil solution (the standard aqueous permeant) by a waste
liquid. The procedure is quite involved and requires considerable effort to
perform. However, considering the significance of the problem, which is the
storage of hazardous wastes in a continuously safe impoundment, the task of
carefully identifying and understanding the impact of wastes on soil flow
properties must be undertaken.
334
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Figure III-8-1. The open exposure tubs lined with polymeric membranes and
partially filled with hazardous wastes. They are covered
with chicken wire and placed in a snallow basin lined with an
elasticized polyolefin membrane, juring rainy weather these
cells are protected by a corrugated plastic cover (Haxo
and White, 1977).
The tubs are filled from 3/4 to 7/8 full with wastes. The liquid level is
allowed to fluctuate about 4 inches. During the exposure period the tub
liners are inspected visually for cracking, opening of seams, and other forms
of liner deterioration. The waste levels and temperatures are measured and
recorded at regular intervals. Water is added wnen levels become too low.
An oily waste which generally has a film of water at the surface tends to
accumulate water (from dew) which does not evaporate significantly. Water,
or actually an oil-water mixture, should be pumped from the bottom of these
tubs to maintain liquid levels and prevent overflows of the waste. The
oil-water mixture removed may be analyzed for pH, electrical conductivity,
percent solids, and other parameters as appropriate. The water in the catch
basin is also monitored for pH and conductivity as a possible indication of
leakage from the tubs containing highly acidic or highly alkaline wastes.
Status of Tub Exposure Tests Underway in Oakland, California:
Long-term tub exposure tests on a roof in Oakland, California, were started
in November, 1976 (Haxo et al, 1977). As of April 1980, only one of the 12
325
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liner specimens that were placed in this test had failed. The tests consisted
of 12 tubs utilizing four wastes (spent caustic, alkaline slop water, nitric
acid waste, and a waste oil) and nine liner materials (elasticized polyolefin,
two PVC's, polyester elastomer, butyl rubber, neoprene, EPDM, CSPE, and
Most of the liners have swelled to some degree after an exposure period
approximately 3. 5 years.
The elasticized polyolefin exposed to the waste oil developed cracks and
leaked on the 517th day of exposure. This liner was observed to have swelled
after one month of exposure and the swelling apparently continued at a very
slow rate until failure. The elasticized polyolefin membrane developed in the
waste/sun interface area, two openings which were oriented alqng folds in the
membrane.
On removal from the tub, physical tests of the exposed liner were run at four
exposure locations:
- Under waste only
- In waste/shade zone
- In shade only
- In waste/sunlight zone
The waste/sunlight zone provided the harshest environment for the liner
material, as shown by the test results in Table 1II-B-1.
No other liner failure had occurred to April 1980, though deterioration of
the exposed liners was evident. The seams in the EPOM liner exposed to nitric
acid wastes had weakened and the caulking appeared cracked, but no leaking had'
been detected. The PVC liner below the acid waste has become hard.- The
liners tended to swell more at folds as well as in the waste/sun zone,^
indicating that both situations should be regularly examined on in-service^
liners. At the sharp corners, the butyl rubber liner was ozone cracking.
TABLE III-8-1. FAILED ELASTICIZEP POLYOLEFIN LINER
EXPOSED TO SATURATED AND UNSATURATED OILS IN OPEN TUB3
*
Test
Thickness, mi Is
Tensile strength, psi
Elongation at break, £
Tensile set, %
S-100, psi
S-200, psi
Puncture resistance, Ib.
Elongation, inches
% Retention of property of exposure to
Original
value
23
2590
£65
445
875
970
26.3
0.97
Waste
only
113
47
89
76
68
64
97
130
Waste +
sun
113
38
81
72
59
46
73
122
Waste +
shade
113
45
83
74
65
63
70
113
Shade
only
98
97
99
100
110
107
135
142
a£xposure time: 506 days from 11/2/76 to 3/23/78.
326
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APPENDIX III-C
TEST METHOD FOR THE PERMEABILITY OF COMPACTED CLAY SOILS
Constant Elevated Pressure Methods
INTRODUCTION
To assess the suitability of compacted clay soils for the lining of waste stora
facilities, the primary laboratory measurement is saturated hydraulic conducti
ity or permeability. Such a measurement should be made on a specimen of so
that has been remolded and compacted in the range of optimum moisture conte
to achieve the maximum density possible for a given compactive effort. AS
Methods 0698-73 or 01557-73 should be used for determining a soil moistur
density relation.
Testing procedures recommended in subsequent paragraphs are not suitable for
determination of field permeaoility values. They are, however, considerec
suitable for performing comparative studies to evaluate the potential in-
fluence of waste leachates on permeability of compacted clay soils that are
candidates for use as liners. As a large variety of waste liquids are placed
in hazardous waste landfills and surface impoundments (Chapter 2), there is a
great need for a specific permeability test that can determine, in reasonable
lengths of time, the potential effects these 'eachates may exert on perme-
ability of clay 1iners. •
In the selection of soils for lining a specific impoundment, the candidate
soil or soils should be tested with the standa'ra aqueous permeant and with a
representative sample of the waste liquid to be impounded. The results will
rank the soil-waste combinations and thus allow the choice of the most favor-
able soil for lining the facility.
The testing procedure is designed to reveal changes in permeability of
the compacted soil specimen when the native soil solution (pore water) is
replaced by the primary and/or secondary permeant. As a simulated native soil
pore liquid, we recommend a 0.01 normal aqueous solution of calcium sulphate.
The permeameter used in this test (Figure III-C-1) is constructed from readily
available and easily modified components. Standard compaction permeameters
and the necessary ASTM procedures are available through most soil testing
supply companies. All components in Figure III-C-1 are in common with the
standard permeameter except for the enlarged liquid chamber, extended studs,
high pressure fittings, Teflon outlet tubing, and Teflon gaskets. Figure
III-C-2 is a schematic of a test setup utilising permeameters.
327
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—PRESSURE INPUT
RELEASE
ou-rurr-
BASE
^—POROUS STONC
TEFUON TU8INO
Figure III-C-1. Schemcitic of the compaction permeameter (Anderson et
al , 1982).
PRESSURIZED AB SCXWCE
COMPACTION
P£RM£AMETEf)
AH TCHT CQOLEQ CHAMSEH
Figure III-C-2.
Schematic of the compaction permeameter test apparatus
(Anderson et al ,1982).
328
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Compacted clay soils often have water permeability values lower than 10"^ cr
sec"^- and it may be necessary to pass one pore volume of standard calciur
sulphate permeant through a soil before a stable baseline permeability
value is obtained. After establishing the permeability baseline, the passage
of at least one pore volume of waste liquid may be necessary to determine
fully the effects that the waste liquid may have on" permeabi 1 i ty of the
compacted clay soil specimen. A pressurized air source should be used tc
increase the hydraulic gradient and thus reduce testing time (Bennett, 1966;
Jones, I960).
The use of large hydraulic gradients has shortcomings. The thickness of
immobilized fluid films on soil particles may be substantially decreased at
large pressures (Yong and Wartkentin, 1975). This would increase effective
pore diameter available for liquid flow and thus increase permeability. Also,
large hydraulic gradients can increase soil particle migration causing soil
clogging and a resulting decrease in permeability (Olson and Daniel, 1979).
Criteria for selecting an appropriate hydraulic gradient depends greatly
on proposed use of the permeability study. Where the objective is to estimate
field permeability values, it has been suggested "to use gradients as close
as those, encountered in the field as is economically feasible" (Olson and
Daniel, 1979). Zimmie (1981) suggested use of hydraulic gradients between 6
and 20 for laboratory studies attempting to duplicate field conditions.
In comparative permeability studies, larger hydraulic gradients are probably
acceptable; however, care should be taken to monitor particle migration.
Variations in permeant liquids may drastically change the permeability of a
given soil (Michaels and Lin, 1954).
Comparative permeability studies use multiple per-neameters to isolate effects
of one or more variables. This testing aporoach has been widely used
in agricultural irrigation "studies evaluating tne influence of various salt
types and concentrations on soils of low permeability (Mclntyre et al, 1979;
McNeal, 1974). Comparative methods have also been used to evaluate the
influence of organic liquids on soils (Michaels and Lin, 1954; Van Schaik,
1970).
In comparative permeability studies, flow should be laminar, and all but the
variable being tested should be held constant. Under these conditions, any
change in permeability can be interpreted as being the result of changes in
the porous matrix. Soil permeability measurements must be carefully taken if
they are to be accurate. Leaks, volatile losses, or channel flow along the
interface of the permeameter and soil will greatly affect permeability values
(Bowles, 1978).
Several authorities on permeability studies have expressed doubts that labor-
atory permeability tests are capable or reproducing field conditions. Olson
and Daniel (1979) noted that the volume of. soil samples used in laboratory
tests is almost always too small to contain statistically significant distri-
butions of macrofeatures encountered in the field (i.e. sand lenses, fis-
sures, joints, channels, root holes, etc). They further noted that, samples
329 '
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taken In the field may be affected either by the sampling method or selectic
of the most uniform or intact sample. Bowles (1978) stated that "the soil^
the permeability device is never in the same state as in the field; it^i
always -disturbed to some extent". Zimmie et al (1981) stated "it is virtual!,
impossible to duplicate field hydraulic gradients in the laboratory. Tes
times become excessive and it becomes difficult to obtain accurate measure
ments of flows and heads at very low hydraulic gradients."
Several factors not incorporated into laboratory tests affect overall permea-
bility of clay. Sherard and Decker (1977) listed primary factors determining
"effective overall permeabiity" of a soil layer as being continuity, regu-
larity, thickness, and characteristics of interbedded layers or lenses.
Laboratory permeability determination on clay liners cannot account for this
type of variability and can only attempt to characterize a homogeneous sample
of clay soil. Other factors that may lead to discrepancies between field and
laboratory permeability values are discussed in detail by Olson and Daniel
(1979).
In the test procedure presented in this appendix, the following form of
Darcy's Law may be used:
where:
K = Permeability (cm s~*)
V = Volume of liquid passed through the soil (car)
A - Cross-sectional area of liquid flow (cm-)
h+1
H = Hydraulic gradient = --
*
h = Hydraulic head (expressed as cm of water)
1 = Thickness of soil specimen (cm).
t = Permeation time (second).,
Permeability values are plotted along the Y-axis, while the cumulative number
of pore volumes are plotted along the X-axis. The number of pore volumes is
obtained by dividing the total volume of leachate (V) by the pore volume of
the compacted soil specimen used in the test. (For an example plot, see
.Figures 4-1 to 4-9 in Chapter 4.)
If there is a failure in the clay liner being tested, a rough estimate of the
time to failure of the real liner can be made by rearranging Darcy's law so
that time is isolated as follows: .. . - . -
330
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t = —
AHK
Assuming, for example, that a sharp permeability increase was recorded undt
H 3 Hg at t = tg and estimating the highest possible gradient in the fiel
equal to Hf (where Hf «Hg), the failure time of the soil liner, tf, will t
given by: H
tf • to ^
One should emphasize that this is not an analysis of the failure time, bu
only a rough estimate of it.
It is important to obtain a permeability value and time incremen-t on each por
volume of leachate passed during a test. Failure to do so will make i
impossible to plot permeability vs pore volume or to perform a "time failure
calculation for the clay soil liner.
EQUIPMENT
1. Soil crusher (C-2 Laboratory Crusher).
2. Soil grinder (Hewitt Soil Grinder).
3. 2 mm sieve (CB-310 Brass Sieves).
4. Moisture cans (LT-30 Tin Sample Boxes).
5. Balance capable of weighing 20 kg. (1-500 Heavy Duty Balance).
6. Drying oven (105°C) to determine water content of soil samples.
7. Compaction molds (CN-405 Standard Compaction Mold).
8. Compaction hammer (CN-4230 Mechanical Compactor).
9. Steel straight edge.
10. Permeameter bases and top plates (K-611 Permeameter Adapter).
11, A source of compressed air with a water trap, regulator and pressure
meter.
12. A fraction collector with automatic timer for collection of samples
over time (Brinkman Linear II Fraction Collector with a multiple
distribution head).
13. An air tight, cooled chamber to limit volatile loss of samples during
and after sampling.
14. A vented hood to hold the compaction permeameters and chamber con-
taining the-fraction collector. (This is a safety precaution to limit
exposure of laboratory personnel to the hazardous chemicals used in
the studies.)
Note: Equipment in Items 1, 3, 4, 5, 7, 8', and 10 can be obtained from Soil
Test, Inc.; equipment in Item 2 can obtained from B, Hewitt Welding
and Repair.
331
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PROCEDURES
1. Obtain sufficient clay soil (ca 30 kg dry weight) to be tested;
Approximately 3 kg dry weight of soil material is needed per com-
paction mold. Break the soil down to golf ball-sized clods and allow
it to air dry.
2. Throughly break up the aggregation of the air dried soil and pass it
through an ASTM No. 4 (4.75 mm) sieve. Where refined clay products
are to be admixed with a native-soil, thoroughly mix the materials
at this point. To improve the reproductibility of a mixture, proper
proportions should be determined using percentage by oven dry weight.
Do not oven dry the actual materials to be blended as this could
alter chemical and physical properties of the liner material.
3. After thoroughly mixing, the soil should be placed in air tight
containers and stored at room temperature until the time of test.
4. Determine the moisture density relations of the soil on five to seven
specimens using ASTM Method D698-78 or D1557-78.
5. Use the remaining soil Co prepare compaction molds at optimum mois-
ture content. Weigh all compaction molds before and after placement
of the soil material to permit the determination of the bulk density,
porosity, and pore volume of each specimen.
6. Fit a valve on top of the permeameter top plate with pressure fit-
tings and connect it to a source of air pressure via copper tubing.
Place a water trap, pressure regulator, and pressure gage in line
between the air pressure; source and permeameter. The water trap
should be placed between the pressure source and regulator to prevent
buildup of debris on the membrane in tne regulator. The pressure
gage should be loaded between the regulator and a pressure manifold
to the permeameters so that the hydraulic head being exerted on the
clay soils can be monitored. Permeameters used for testing of clay
liners must be capable of safely operating with hazardous materials
including industrial solvents, volatile compounds, corrosive acids,
and strong bases. All gaskets used in permeameters should be Teflon
to prevent deterioration and possible blowout from contact with these
aggressive permeant liquids. To avoid leakage around the hard Teflon
gaskets, all metal surfaces against which the gaskets seat should be
wiped clean of grit. Permeameter components have been found to
withstand continous operational use at pressures up to 60 psi.
Volatile' losses may occur during sample delivery from the outlet
tubing to the leachate collection bottles. To limit these volatile
losses, the top of each leachate collection bottle should be fitted
with a long stem funnel and placed in an air-tight cooled compart-
ment. When volatile hazardous chemicals are used, the entire test
apparatus should be set in a vented hood.
332
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7. Place the standard permeant (0.01N CaS04) in the chamber above tl
compacted soil. To avoid channel formation, clay should be allow*
to seat at low pressure. By allowing standard permeant to stand c
the soil for 24 hours, an effective seat is obtained for the top fe
millimeters of the clay core. This thin layer will minimize tl"
possibility of bulk flow along the permeameter sidewalls. The res
of the specimen should adequately seal when the permeant is force
into the compacted soil specimen at elevated pressures. With severa
specimens producing leachate, it may be desirable to have an auto
matic fraction collector. This is especially useful with long-ter
tests.
8. To limit the volume for diffusive mixing of leachate samples afte
they have passed through a compacted specimen, the leachate outle
should be fitted with an adapter to 3 mm (inside diameter) Tefloi
tubing. The use of translucent Teflon at the permeameter outle-
provides a convenient window through which to monitor the expulsioi
of entrapped air. Standard permeant should be passed through th<
permeameter'unti1 no air bubbles are visible in the outlet tubing,
If soil piping occurs, eluted soil clays will be visible either
clinging to the inside walls of the outlet tubing or as a suspensior
in the collected samples. The liquid chamber should be completely
filled, and a constant pressure applied tnrough the pressure input
(10 psi should be sufficient to reduce testing time and minimize
particle migration in the soil). This constant pressure should be
maintained until no air bubbles are visible in the outlet tubing and
a constant permeability value is obtained. If the constant (equi-
librium) permeability values are not consistently below 1 x 10~' cm
sec"1, the soi1 is probably not suitable as a liner material.
9. Oepressurize the permeameter and remove the top plate and liquid
chamber. If the soil nas shrunk, it is probably not suitaole as a
1 iner material .
10. If the soil has expanded into the liquid chamber, remove the'excess
soil with a straight edge without smearing the soil surface, collect
all the removed soil material and ootain its oven dry weight to
permit recalculating bulk density, porosity, and pore volume of the
soil specimen. If the soil surface is smeared during the removal of
the excess soil, pass standard leachate to assure that the Permea-
bility has not been altered.
11. Place the waste permeant in the liquid chambers of the permeameters
and repressurize the system. Maintain at least two permeameters with
standard permeant for the duration of the tests. Where both a
primary and secondary leachate are expected to be generated by the
waste, each waste liquid should be,used on at least two permeameters.
To collect the primary leachate, fill a large Buchner funnel with the
waste and subject it to sufficient suction to extract the liquids
present in the waste. Repeat this procedure until approximately
333
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two liters of primary leachate (per permeameter) has been generated—
Secondary leachate should be generated by the standard EPA procedu™
agreed upon at the tine of test. For example, shake 5 kg of waste
with 2.5 liters of water (per permeameter). The resulting solution
can be filtered using a large Buchner funnel.
12. Pass at least one pore volume of the appropriate permeant through
the soil specimen. If the specimen exhibits a trend of increasing
permeability, pass an additional pore volume of the leachate through
the soil. If the soil specimen maintains a permeability below
1 x 10"' cm sec"1 and exhibits a decreasing or stable permeab-
ility after passage of the first pore volume, the permeameter
should be disassembled to examine the soil specimen.
13. If the soil specimen has shrunk, it is unlikely to be suitable as a
liner material.
14. If the soil specimen has expanded, repeat the above procedures
beginning with Step 10.
15. If the soil specimen ha:; not. changed volume, reassemble the perme-
ameter and place the standard permeant (0.01N CaS04) in the -liquid
chamber. Pass additiona' standard permeant. If the permeability of
the soil has consistently stayed below 1 x 10"^ cm sec"1 as measured
with the standard, primary, and secondary leachate, proceed to Step
16.
16. Examine the translucent Teflon outlet tuning for signs of particle
migration out of the soil specimen. If there i-s evidence of soil •
migration, pass an additional standard permeant to observe if the
internal erosion continues. If it continues, the soil probably
will not be suitable for use as a Hner material. If the soil
migration stops, proceed to Step 17.
17. Oepressurize the system and extrude the soil specimen from the
compaction mold to examine it for signs of cracking, internal
erosion or soil piping, dissolution, structural changes, or any other
difference from the soil specimens that received only standard
leachate. If there are none of the above signs that the soil has
deteriorated due to contact with the waste leachate, the soil should _
be suitable as a liner material to contain that particular waste.
Comments
This procedure is designed to reveal changes in flow properties due to the
replacement of the soil solution (the standard aqueous permeant) by a waste
liquid. The procedure is quite involved and requires considerable effort to
perform. However, considering the significance of the problem, which is the
storage of hazardous wastes in a continuously safe impoundment, the task of
carefully identifying and understanding the impact of wastes on soil flow
properties must be undertaken.
334
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At present, a designer cannot rely on available data and a body of pas
experience because such data do not exist. The difficulties that are linke
with determining the permeability of a compacted soil liner specimen for
particular waste are primarily connected with the following two testir
conditions:
1. Compacted soil specimens will have low permeabilities, e.g. les
than 10"' cm sec . Under such circumstances, a considerabl
time is required to obtain a steady K value, even when the standar
permeant liquid is used.
2. To assess the effect of water replacement by a waste, almost <
complete replacement has to take place. This requires the passage 01
at least two pore volumes of waste liquid through the specimen. For
a specimen with a permeability equal to 10"° cm sec , even c
hydraulic gradient as large as 300 may require several months if
ie specimen is of a reasonable size, for example D = L = 3 inches.
To decrease specimen thickness will certainly be a waste of effort
since the test condition may not then simulate the field situation.
It is acknowledged that the recommended test procedure is a research project
but, at the present time, *o shortcuts are available; however, this procedure
must be undertaken in order to generate raw data to be used in the design of
the waste soi1 1iner.
335
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REFERENCES
APPENDIX III-C. TEST METHOD FOR THE PERMEABILITY OF COMPACTED CLAY SOILS
Anderson, D. C., K. W. Brown, and J. Green. 1982. Organic Solvent Effects
on the Permeability of Clay Soils. In: Proceedings of the 8th Annual
Hazardous Waste Research Symposium. EPA-60Q/9-82-002. U.S. Environmental
Protection Agency. Cincinnati, OH. 549 pp.
ASTM 0698-78. Moisture Density Delations of Soils and Soil-Aggregate Mixtures
Using 5.5-lb (2.49-kg) Rammer and 12-in. (305-mm) Drop. American Society
for Testing and Materials. Philadelphia, PA.
ASTM 01557-78. Mositure Density Relations of Soils and Soil-Aggregate Mix-
tures Using 10-lb (4.54-kg; Rammer and 18-in (457-mm) Drop. American
Society for Testing and Materials. Philadelphia, PA.
Bennett, J. P. 1966. Permeability of Soils at Elevated Permeant Pressures.^
Master's Thesis. Colorado State University, Fort Collins, CO. I
Bowles, J. E. 1978. Engineering Properties of Soils and Their Measurement.
2nd ed. McGraw-Hill, NY.
Jones, C. W. 1960. Permeability Tests With the Permeant Water Under Pres-
sure. Earth Laboratory Report # EM-559. Division of Engineering Lab-
oratories Commissioner's Office. Denver, CO.
Mclntyre, D. S., R. 8. Cunningham, V. Vatanakul, and G. A. Stewart. 1979.
Measuring Hydraulic Conductivity in Clay Soils: Methods, Techniques, and
Errors. Soil Sci. 128(3):171-183.
McNeal, B. L. 1974. Soil Salts and Their Effects on Water Movement. In:
Drainage for Agriculture. J. Van Schilfgaarde, ed. Am. Soc. Agron.
Madison, WI.
Michaels, A. S. and C. S, Lin. 1954. Permeability of Kaolinite. Ind. Eng.
. Chem. 46(6) .-1239-1246.
Olson, R. E. and D. E. Daniel. 1979. Field and Laboratory Measurement of the
Permeability of Saturated and Partially Saturated Fine-Grained Soils.
Presented at ASTM Symposium. Permeability and Groundwater Contaminant
Transport, June 21, 1979. Philadelphia, PA.
336
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REFERENCES FOR APPENDIX I II-C. (continued)
Sherard, J. L., and R. S. Decker. 1977. Summary-Evaluation of Symposium
Dispersive Clays. In: Dispersive Clays, Related Piping, and Erosion
Geotechnical Projects. ASTM STP 623. American Society for Testing «
Materials. Philadelphia, PA. pp. 467-479.
Van Schaik, J. C. 1970. Soil Hydraulic Properties with Water and with
Hydrocarbon Liquid; Can. J. Soil Sci. 50:79-84.
Yong, R. N. , and B. P. Warkentin. 1975. Soil Properties and Behavio
Geotechnical Engineering 5. Elsevier Scientific Pub. Co., NY. 449 p
Zimmie, T. F. 1981. Geotechnical Testing Considerations in the Determinati
of Laboratory Permeability for Hazardous Waste Disposal Siting. I
Hazardous Solid Waste Testing: First Conference, STP-760. R. A. Conw,
and B. C. Malloy, eds. American Society for Testing and Material
Philadelphia, PA. pp. 293-304.
337
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APPENDIX III-D
VOLATILES TEST OF UNEXPOSED POLYMERIC LINING MATERIALS
(Matrecon Test Method 1 - October 1982)
Scope-
This test is to be performed on unexposed membrane liner materials.
Significance
This test can be used to determine the volatile content of an unexposed
sheeting, including water, volatile oils, and solvents. Nonvolatile dissolved
or absorbed components of a specimen will be determined by the extractables
test which is run after the volatiles have been removed (see Matrecon Test
Method 2). The volatile content should be determined as soon as possible
after the liner has been received., 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.
Defini tions
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.
- Air oven.
Test Soecimen:
Two-inch diameter disks died out of the sheeting, as received.
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 two-inch diameter disk so that the lines fall approximately
in the middle of the specimen.
3. Weigh specimen in- tared, closed container to the nearest 0.0001 g.
Record weight "as received weight".
338
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4. Dry specimen out on Teflon screen for two hours at i05i2°C.
5. Cool in desiccator for 20 minutes.
6. Weigh on analytical balance to 0,0001 g; record as the "oven dr
weight".
7. Measure diameters in machine and transverse directions. Recor
to 0.001 inches.
8. If machine direction is unknown, find and record largest and small
est diameters of disk. Mark small diameter as machine direction o
disk as shown in Figure III-O-l. Use the dried disk to determin
the orientation of the sheeting from which it was removed.
GRAIN
Oven Dry
As Received
Figure III-O-l. Machine direction determination.
9. Retain specimens for additional testing, e.g. specific gravity,
thermogravimetry , extractables , etc.
Calculations
Calculate the percent volatiles as follows:
Volatiles, % = C(A-8)/A] x 100
where:
A * grams of specimen, "as received weight"
8 » grams of specimen, "oven dry weight"
Report
1. Identification of sheeting.
2. Result of above calculation of volatiles.
339
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APPENDIX III-E
TEST FOR THE EXTRACTABLE CONTENT OF UNEXPOSED LINING MATERIALS
(Matrecon Test Method 2 - October 1982)
Scope
This procedure- covers the extraction of pi astici'zers, oils, and other
solvent-soluble constituents of polymeric lining materials with a solvent that
neither decomposes nor dissolves the polymer.
References
This procedure generally follows ASTM D3421, "Extraction and Analysis of
Plasticizers Mixtures from Vinyl Chloride Plastics". See also ASTM 0297,
"Rubber Products-Chemical Analysis", paragrapns 16-18.
Significance
The extractable content of a polymeric lining material can consist of
plasticizers, oils, or other solvent-soluble constituents that impart or help
maintain specific properties such as flexibility and processabi1ity. During
exposure to a waste, the extractaoles content may be extracted out by the
waste resulting in a change in properties. Anotner possibility is tha
during exposure the material could absorb non -/olati! izable constituents frc
a waste. Measuring the extractable content or anexposed lining materials is,
therefore, useful for monitoring the effect of an exposure on a lining
material. The extract and tne extracted liner oorained by this procedure can
be used for further analytical testing, e.g. gas chromatography, infrared,
ash, thermogravirnetry, etc. for fingerprinting tne liner.
Apparatus
- Aluminum weighing dishes.
- Analytical balance.
- 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.
Note: 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.
340
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Reagents
Table III-E-1 lists the recommended
liners of eacn polymer type.
solvents for tne extraction of membra
TABLE III-E-1. SOLVENTS FOR EXTRACTION OF POLYMERIC MEMBRANES
Polymer type
Extraction solvent
Butyl rubber (IIR)
Chlorinated polyethylene (CPE)
Chlorosulfonated polyethylene (CSPE)
Elasticized polyolefin
Epicnlorhydrin rubber (CO and ECO)
Ethylene propylene rubber (EPOM)
Neoprene
Nitrile rubber (vulcanized)
Nitrile-modified polyvinyl chloride
Polyester elastomer
Hign-density polyethylene (HOPE)
Polyvinyl cnloride (PVC)
Thermoplastic olefimc elastomer
Metnyl ethyl ketone
n-Heptane
Acetone
Methyl ethyl ketone
Methyl ethyl ketone
Methyl ethyl ketone
Acetone
Acetone
2:1 blend of carbon
ride and methyl al
Methyl ethyl Ketone
Methyl etnyl ketone
2:1 blend of carbon
ride and metnyl al
Methyl ethyl ketone
or acetone
tetrachlo-
ohol
tetrachlo-
onoi
Note: Because lining materials can be sneetings based on polymeric al-
loys wnich are marketed under a trade name or under tine name o1
only one of 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 four-:, it is important tnat tne
same solvent be used for determining :ne extractables across' tne
range of exposure periods.
Sample size
If using tne Soxhlet extractor, about five grams of d'evolati 1 ized material are
needed per extraction. If using -tne ruboer extraction apparatus, aoout two
grams are needed. All extractions snould be run in duplicate.
Procedure
1. Cut the sample into cubes no larger than 0.25" on a side.
2. Weigh sample into an aluminum weighing dish and dry in moving air at
room temperature for more than 16 hours.
3. Place in air oven for two hours at 105t2°C. Weigh the sample.
4. Weigh the sample into a tared extraction thimble. Plug small
thimbles with • piece of cotton-wool to prevent the pieces from
floating out or the thimble. (Large thimbles are tall enough to stay
above the level of the liquid.)
341
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5a. For PVC and CPE materials: Add 200 ml of extraction solvent to tft
500 ml flat-bottom distillation flask. Add boiling beads to reduc
bumping. M
5b. For other materials: Dry and preweigh a thin-walled Erlenmeyei
distillation flask. Add 200 ml of extraction solvent to the flask.
6. Place the thimble in the extractor barrel, put the condensor ir
place, and run the extraction a minimum of 22 hours. Aluminum
foil can be- wrapped around the extractor and flask to increase the
distil lation rate.
7a. For PVC and CPE materials: When the extraction is complete, rinse
all the solvent from the extractor oarrel into the distillation
flask. Decant the solvent from the flask into a dried, tared 500 mL
Erlenmeyer flask and then evaporate on a steam bath with filtered
air. Place the flask in an oven at 70±2°C and dry two hours.
Hold the extract for further testing e.g. gas chroma to graphy and
infrared.
7b- For other materials: When the extraction is complete, rinse all the
solvent from the extractor barrel into Che distillation flask.
Evaporate the solvent from the flask on a steam bath with filtered
air. Place the flask in an oven at 70i2°C and dry two hours.
Hold the extract for further testing.
8. If the extract contain;; constituents which may volatilize
the evaporation procedure or is to be used for further analysis,
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.
9. Remove extracted liner from the thimole after excess solvent is
removed and place in a tared aluminum weighing dish. Heat to
constant weight at 105°C. Extracted PVC specimens cannot be dried to
a constant weight at 105"C when they are extracted with a blend of
CC14 and CH^OH. It is recommended that the sample be dried 72
hours at 105°C. Hold the extracted liner for further testing.
Note: In cases where the extracted soecimen sticks to the extrac-
tion thimble, the extraction thimble should be dried to con-
stant weight at 70°C before the extraction and the weight
recorded as the true weight of the thimble. After the ex-
traction, the extracted liner can be dried to a constant weight
in the thimble.
Calculations
Calculate the percent volatiles as follows:
Volatiles, % - C(A-B)/A] x 100
where:
A = grams of specimen, as received
B = grams of specimen after 2 hours at 105°C
342
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Calculate the percent extractables as follows:
Extractables, % = (3/A) x 100
where:
A = grams of specimen
8 - grams of dried extract
Note: In cases where the extract may contain some constituents whic
volatilized while the extraction solvent was evaporated, tf
percent extractables should also be calculated as follows:
Extractables based on loss from ..^ecimen, % = C(A-B)/A]
A = grams of specimen
B « grams of extracted liner
Report^
1. Identification of sheeting.
2. Extraction solvent.
3. Volatiles.
4. Extractables,
5. Extractables based on loss from specimen, if calculated.
343
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APPENDIX III-F
ANALYSIS OF EXPOSED POLYMERIC LINING MATERIALS
(Matrecon Test Method 7)
Liner as received
from service or
test. WQ
TGA
volatile orgamcs
Pfasticizer
Polymer
Carbon black
Ash
desiccator
4 days, 50° C
Dehydrated specimen, l,Vj
Air oven
2 hours, 105°C
Ash
De^olatilized specimen, '/V->
GI /
extraction
TGA
Vlotrecan Method 2)
Elemental
Analysis by
AAS
f X ~—^
Plasticuer
Polymer
Caroon black
Extr
W
Ash
act.
7
Solid residue,
W4
r t
GC
IR
CHONS
Residua
Polymer
TGA
r
solvent
Carbon Black
Ash
TGA * thermogravimetric analysis .. . . - -
GC * gas chromatograpny
IR * infrared spectroscopy
AAS =• atomic absorption spectroscopy
CHONS = carbon, hydrogen, nitrogen, oxygen, and sulfur determination
344
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APPENDIX IV
INSTALLATION OF FLEXIBLE POLYMERIC MEMBRANE LINERS
The installation of flexible membrane liners requires a significant plannii
effort prior to construction. This planning effort must include considerate
of the storage and security of all necessary equipment, installation equif
ment, manpower requirements, the placement operation, field seaming, anchorir
and sealing, quality control, inspection, and protection of placed liners
These considerations are discussed in detail in this Appendix.
IV.1 On-site Storage of Materials and Equipment.
Items requiring storage will include the liner materials and all equipmen
necessary for installation. Figure IV-1 shows liner material package
and shipped to the site. Most liner material is packaged in folded panels o
rolls which may weigh from 2,000 to 5,000 pounds each. All membrane liner
should be stored cut of sunlight if possible to prevent their degradatio
and to minimize blocking. Slocking occurs when the liner material stick
together, causing del ami nation or ripping when the roll is unrolled onto th<
subgrade. Figure IV-2 shows the result of blocking of a reinforced liner
with the scrim exposed. This damage will have to be repaired. Liners- are
shipped rolled or accordion folded in cardboard boxes and placed on wooder
pallets. The liner material can thus be movec -~-om the storage site to the
construction site by means of a fork-lift true*, or some other suitable pieca
of equipment, without damage.
An important consideration in the storage of al1 equipment and liner materials
at the site is prevention of vandalism and theft. This can be accomplished by
erecting a temporary fence or placing the material in an existing secured
area. The need for an elaborate storage system can be minimized if the job can
be planned so that all equipment and materials necessary can be brought to the
site, and installation begun immediately after receipt'of liner materials
and location of equipment at the site.
IV.2 Installation Equipment
Necessary equipment needed to install flexible membrane liners depends on the
type of liner material to be installed, the complexity of the job with respect
to side slope steepness, the number of penetrations, the number of seals re-
quired, and the length of installation time anticipated. Some means to move
the liner material from storage to the impoundment site is necessary. A fork-
lift truck is very useful for this purpose, though other pieces of equipment,
such as a backhoe or front-end loader, can,, also be used. High-density poly-
ethylene liner material is brought to the site in rolls rather than pallets
and requires a crane or front-end loader for moving to the installation site.
345
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Figure iv-l.
pa,,ets
346
-------
Figure IV-2. Damage to a fabric reinforced liner caused by "blocking" of th<
.sheeting. Blocking can occur during shipping or storage wher
sheeting is rolled or folded and sticks together under warn
conditions. The exposed fabric scrim must be repaired.
These rolls may .weigh up to 10,000 pounds and special straps are used to move
them (Figure IV-3).
A backhoe may prove useful
ed during installation.
move sand
if touch jp
> bac:
-------
Figure IV-3.
High-density polyethylene (HOPE) is shipped to the site rolled
onto drums. Each roll may weigh up to five tons.
348
-------
•f I.
Figure IV-4,
Special equipment for seaming of high-density polyethylene
(HOPE)-. An automatic welder is shown above; a hand held welder
is shown below. With both.devices molten HOPE is extruded
between the overlap of the two sheets being seamed.
349
-------
Figure IV-5.
This crew is using
seamed. The board
rope shown in the picture.
a board for support under
is pulled along under the
the area being
liner with the
It is necessary to have some means to control the effects of wind on
which have been laid on the subgrade. This can be accomplished using
tires, or more commonly, sandbags placed every fi-ve to ten feet along unseamed
edges. Figure IV-6 shows how sandbags can be used to prevent wind damage to
liner material.
Many of the liner materials require "surface cleaning where the seam is to be
made prior to actual seaming. Therefore, a sufficient supply of clean cotton
rags must be available to the seaming crew. In addition, natural brushes and
stainless steel scouring pads are necessary, particularly for seaming CSPE, as
the surface cure must be removed prior to seaming. Heat guns should be
available when solvent seaming is to take place. These guns provide a means
to bring the liner material to a suitable temperature in the event the ambient
temperatures are below 60* F. Figure IV-7 shows the use of a heat gun to warm
the liner. If trichlorethylene is used for seaming, a heat-gun shoufd be used
with extreme caution, as toxic phosgene gas can be formed. Seaming crews
using tricnloroethylene should not smoke on the job as inhalation of smoking
materials in the presence of tr:chloroethylene produces the same phosgene
gas. Respirators are often needed, especially when crew members must work in
confined areas and use solvents. An electric generator and sufficient exten-
sion cords are necessary if heat guns are used. A crayon should be available
for marking the location of seams.prior to the application of solvents.
Additional equipment needed for the installation of liners includes caulking
compounds and caulking guns, pails for washing solvents, paint brushes or
350
-------
"
Figure IV-6. Sandbagj
351
-------
Figure IV-7. Heat
are used to facilitate fie,d seaming.
352
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other applicators, solvent resistant gloves, safety goggles for men *orkir
with solvents, knee pads, shoes with flat soles to prevent damage to th
liner, scissors and a utility knife, hand-held earth tampers, hand rakes an
shovels, stakes and string to help in the spotting of the panels.
Large sections or panels of a liner are often moved across the subgrade b
field crews. Wooden dowel rods should be provided to the field crew to use i
moving panels without stretching the edges which will be seamed. These dowe
rods are placed on the edge of the panel; the panel is then rolled c/:o thi
dowel rod. This provides a handle so that the panels can be moved withou'
stretching the liner.
A list of the equipment often required for installation of membrane liners is
presented in Table IV-1.
IV.3 Manpower Requirements
Manpower requirement for the installation of liner materials is obviously a
function of the rate that the installer wants to place panels and accomplish
field seaming. Typically, installation contractors will have anywhere 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. He ay not
directly participate in the unrolling and spotting of panels or in field
seaming. However, he must be experienced in installation of the specific liner
material.
Crew size requirements also depend on the complexity of the installation and
the experience of the field crew. If "-a majority of the crew members are
recruited locally, they probably will recuire training during installation. At
the present time, the trend is toward having installation contractors retain
field supervisors who travel from job site to job site. 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 numcer of structures or penetra-
tions in the facility. For example, if three or four concrete pillars are
located within the area of one panel, this situation will require more man-
power than if the panel is to be placed on a flat subgrade. In many instances,
the owner of the facility may provide necessary manpower on an as-needed basis
to the installation contractor. This arrangement will minimize the direct cost
of installation to the owner, as excess work loads can be fulfilled with
temporary labor.
IV.4 Liner Placement
Table IV-2 enumerates principal considerations that installers should follow
in placing a specific liner. Before moving panels from the storage site to
the installation location a number of tasks must be performed. 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 panels can
be unrolled along and parallel to the anchor trench in the width direction.
Other things that must be accomplished prior to panel spotting are: (1) the
353
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TABLE IV-1. EQUIPMENT AND MATERIALS FOR INSTALLATION OF
FLEXIBLE MEMBRANE LINERS
Item
Use
Fork lift
Tires, sandbags
Proper adheiives
Portable electric generator
Air lance
Vacuum box
Hand-held earth tampers
Miscellaneous materials:
-Adhesive applicators ( p a •' n t
brushes, caulking guns, rollers,
etc.).
- Liner 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
pa-nels, 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
Air compressor
To move liner panels and backfil
anchor trenches.
To anchor unseamed panels to preven
wind damage.
To make field seams and seal linei
around concrete or steel penetrations,
To operate heat guns or lighting for
working at night.
Quality control testing of field
seams.
Testing the integrity of field seams.
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.
354
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TABLE IV-2. CONSIDERATIONS DURING LINER PLACEMENT
Follow manufacturers' recommended procedures for adhesive system, se<
overlap, and sealing to concrete.
Use a qualified installation contractor having experience with membrar
liner installation, preferably the generic type of liner being installec
Plan and implement a quality control program which will help insure tha
the liner meets specification and the job is installed per specifications
Inspection should be documented for review and record keeping.
Installation should be done during dry, moderately warm weather if possible
Subgrade should be firm, flat, and free of sharp rocks or debris.
subgrade should be raked smooth or compacted if necessary; (2) there should b<
no standing water in the impoundment; (3) any concrete structures that must be
seamed around should be prepared prior to unrolling of any panels; (4) ii
skirts are to be used around footings on concrete structures, these must be ir
place prior to the beginning of panel placement; (5) any outflow or inflov
structures or other appurtenances snould be in place.
Placement often begins with the unfolding or rolling of the panels lengthwise
as shown in Figure IV-8. The panels are then unfolded in the width directions
either down the side slope or across the floor (Figure IV-9). The field crew
then begins to position or "spot" the panel into its proper location, (Figure
IV-10). As panels are spotted and seamed toget.ner, sand bags are placed as
shown in Figure IV-6 The instructions on the boxes containing the liner must
be followed to assure the panels are unrolled in the proper direction with the
correct side exposed for seaming (Figure IV-11). The panels should be pulled
relatively smooth over the subgrade (Figure IV-I2). If the subgrade is smooth
and compacted, then the liner should be relatively flat on the subgrade.
However, sufficient slack must be left in the material to accommodate any
possible shrinkage due to temperature changes.
IV-5 Field Seaming
The panels should be unfolded and spotted so that a sufficient seam overlap
of the adjacent panel is maintained. Figure IV-13 shows two examples of
proper overlap. Seam overlap varies with liner manufacturer and the liner
type. -Recommended overlaps vary from 4 to 12 inches. Figure IV-14 illustrates
typical factory and field seams.
Field seaming is a critical factor in flexible membrane liner placement. The
liner manufacturers have recommended procedures and adhesive systems for
achieving successful field seams. If the manufacturer does not have a recom-
mended bonding system, then the use of thatJiner material should be question-
ed. Generally three methods are used to 'seam materials in the field. These
355
-------
or
356
-------
•«*&
Figure IV-9.
Workmen "pull" the panel across the subgrade.
iis step may be difficult to accomplish during
windy conditions.
357
-------
Figure IV-10.
Once a panel has been unfolded, the crew
"spots" or positions it in the proper location.
358
-------
Figure IV-ll.
359
-------
Figure IV-12.
Each panel must be pulled smooth, leaving enough slack to
accommodate anticipated shrinkage due to temperature changes.
are bodied solvent, heat, or contact adhesive. Solvent and contact adhesiv^j
systems are the most prevalent. The installation contractor should'use
the manufacturer's recommended procedure.
The integrity of the field seam is determined :y many factors. The most
important factor is that the adhesive system used must be compatible with the
liner material and suitable for use under actual field conditions. As pre-
viously indicated, the liner manufacturers or installers have adhesive systems
that work best for the products they make or work with. These systems normal-
ly have limitations with regard to temperature. Most adhesive systems work
best at temperatures greater than 60°F.
Another important factor in field seam integrity is that the surfaces to be
seamed are clean and dry when the field seams are made. The presence of any
moisture can interfere with the curing and bonding characteristics of the
adhesive used. The presence of any dirt or foreign material can jeopardize
the seam strength and provide a path for fluid to migrate through the seam.
360
-------
*r*y«««i«*T- *£* "
M&f-T-^f--^
*?<*•' "•'•.
=& •> > -
-*i -.>*• ^
^x,
•><•,,- - JS^*j^
--.--^f--' i-'-^p^i
_; -3^--A.r-*gj
-rff'c.r:^-.
7A
r. .-:>
^V^^>
Figure IV-13. Sufficient seam overlap must be raintained.
Manufacturers usually specify minimum overlap
for field seams. K
361
-------
1/4" to 1" SELVAGE EDGE
FLEXIBLE MEMBRANE LINER
%" to 1" SELVAGE EDGE
BODIED SOLVENT
ADHESIVE
4" to 12"-
^ FLEXIBLE MEMBRANE LINER -^
Figure IV-14 Typical factory seam (aoove) and field seam lap jointed. (From
Small, 1980).
underneath the liner and the overlap is sufficient, then the top liner ma-
terial should be peeled back and the surface prepared for the adhesive (Fig.
IV-15). In the case of some liner materials, e.g. EPOM and CSPE, a surface
cure must be removed with a solvent wash prior to seaming. Field crews should
have suitable gloves to prevent skin irritation from the solvents (Figure
IV-16). Respirators and eye protection may also be required. Once the surface
cure has -been removed, the adhesive can be applied to the liner material.
Figure IV-17 shows the application of both a solvent and a contact adhesive.
Generally, with a bodied solvent adhesive, the two surfaces should be placed
together immediately and rolled with a steel or plastic roller perpendicular
to the edge of the panel (Figure IV-18). Contact adhesive systems require
that a certain tackiness be achieved before the two surfaces are placed
together.
The crew should be careful not to allow any wrinkles to occur in the seam
(Figure IV-19). All surfaces should be flat and rolled. It is important,
whatever adhesive system is used, that the adhesive be applied uniformly.
Field seaming should normally begin at the center of a panel and continue to
each end, of the seam. This minimizes large wrinkles which could occur if
seaming began at one end or the other. In all-cases, the adhesive system to be
used by the field seaming crew should be that recommended by the manufacturer
or a suitable substitute approved for a specific job.
362
-------
Figure IV-15.
The surfaces to be seamed must be cleaned to
remove dirt. Cleaning is usually accomplished
with a sol vent.
363
-------
Figure IV-16.
Seaming crews working wi tn solvents are advised
to use gloves for protection.
Generally, panels are placed so that field seams will run perpendicular
the toe of the slopes; that is, the seams will run up and down rather
along the side slopes. A good rule of thumb is always to place seams verti-
cally on side slopes where possible without decreasing panel size or in-
creasing field seaming. This practice minimizes stress on uncured field
seams.
Installation of liner materials and field seaming during adverse weather
conditions require special considerations with respect to adhe'sive systems
be a minimum for most
astic materials since
also affects the rate
become strong. Most
1 iner material itself
and temperature limitations, e.g. 50°C is considered to
materials. This is particularly true with the thermop
their properties change with temperature. Temperature
that solvents will evaporate and the rate that seams
adhesive systems work best when the temperature of the
is above 60°F. When ambient temperatures are below 60°F and a solvent
adhesive system is being used, heat guns can provide an effective means to
help bring the temperature of the liner material up to ideal conditions.
Extreme caution must be exercised when using heat guns around flammable
solvents, which may ignite, and chlorinated solvents which may generate
the toxic gas, phosgene.
Cold weather seaming requires that the field crew.exercise cauti-on when making
seams to assure that the temperature of the liner material reaches minimum
acceptable conditions. A cold weather contact adhesive is sometimes used.
Field seaming during precipitation should be avoided.
364
-------
Figure IV-17.
Field seaming. Adhesives are applied to the
1iner materials.
365
-------
Figure IV-18.
Rolling the seam. After the proper adhesive
has been applied, the seam is rolled smooth.
Depending upon the location and the weather conditions, the number of panels
placed in one day should not exceed the number which can be seamed in one day.
This assures that, should bad weather conditions occur overnight, unseamed
panels will not be left on the subgrade, subject to damage, especially from
wind.
IV.6 Anchoring/Sealing Around Structures/Penetrations
Proper anchoring of the liner around the impoundment perimeter as well as
conscientious tailoring and sealing of the liner around penetrating structures
are essential to sa:'sfactory liner performance. Generally, in cut-and-fill
type impoundments, the liner- material, is anchored at the top of the dike or
berm one of two ways: (1) using i:he trench-and-backfi 11 method (Figure
IV-20), or (2) anchoring to a concrete structure. The trench-and-backfill
method seems to be recommended most often by liner manufacturers, probably due
366
-------
Figure IV-19.
Repairing a wrinkle at the seams. The wrinkle is first pre-
heated with a heat gun (top); after applying adhesive, the
wrinkle is folded; the wMnk.le has been rolled smooth and
washed with a solvent; a patch is applied
(bottom). Thicker sheeting, e.g. 45 mil
and use of a cover strip.
as a final step
may require slitting
367
-------
/
,- Trench cut by trenching machine
/ Insert lining, backfill and compact
1% Slope
12" to 16"
i — 12" —
Top of Slope
6"
Minimum
Radius
Lining
Stable compacted soil or existing concrete,
gunite or asphalt concrete
Figure IV-20.
Trench and backfill design for ancnor-ing the perimeter of a
membrane liner at the top of the pond sidewalls (Kays, 1977).
to its simplicity and economy. Excavation of the anchor trench in preparation
for laying the liner is usually accomplished with d trenching machine such as
a ditch witch or by using the blade of a bulldozer tilted at an angle. The
latter method is considered to be less desirable. Dirt from the excavation
should be spread away from the pit and smoothed to facilitate unrolling and
spotting of panels.
Before opening and spotting the panels, provisions should be made for tempor-
arily securing the edges of the liner panels in the anchor trench while the
seaming" takes place. After the seaming crew has completed the seams for a
particular panel, the trench is backfilled with earth that was excavated
from the trench. The trench should not be backfilled until after the panels
have been seamed so that panels cart be aligned and stretched, if necessary,
for wrinkle-free seaming. If the trench (and the edge of the liner) is to be
capped with concrete curbing, it is; desirable to position reinforcing rods
vertically in the trench prior to backfil ling. These reinforcing rods serve
to hold the liner in place while the seaming is done.
368
-------
The perimeter of the liner may also be anchored to a concrete structure ale
the top of the berm or dike. This is usually accomplished with anch
bolts embedded in the concrete and batten strips composed of a materi
resistant to attack by the chemical(s) to be stored in the impoundmen
Concrete that is to come into contact with the liner should have rounded edg
and be smooth and free of all curing compounds to minimize abrasion a
chemical interaction with the liner material. Anchor bolts should be pos
tioned not more than 12 inches apart on centers. Concrete adhesive is appl i
in a strip (minimum width 3-6 inches, depending on the liner material) betwe'
the liner and the concrete where the batten strips will compress the liner •
the concrete. A strip of lining material (chafer strip) may be sandwich!
between the liner and the concrete wherever the liner material contacts <
angle in the concrete structure to prevent abrasion. The batten strips ai
positioned over the liner material and secured with washers and nuts to tf
anchor bolts. Mastic should be used to effect a seal around the edge of U
liner material. Several alternative methods for anchoring to concrete struc
tures are shown in Kays (1977).
Depending on the design and purpose of the impoundment, one or more types o
structures may penetrate the liner. These penetrations could include inlet
outlet, overflow, or mud drain pipes; gas vents; level indicating devices
emergency spill systems; aipe supports; or aeration systems. Penetrations ma
occur in the bottom or through one of the sidewalls, deoending -joon thei
function. Because tailoring and sealing the liner around structures can fr
difficult and offers a possibility for failure of the liner, several manufac
turers recommend that over-cne-1iner pipe placement be used wherever possible
This design facilitates future repairs or maintenance to the piping system,
When penetrations through the liner are necessary, most manufacturers recom-
mend specific material s^ and procedures to be .sac! to estaolish an effective
seal around the various types of penetrations. 3roper design of the penetra-
tions and selection of an adhesive material trat is' compatible with the liner
are important factors to be considered relative :: expected liner performance.
For instance*, some liner materials are not easily sealed to concrete. Selec-
tion of alternative materials may be required. Other materials, on the other
hand, may offer optimal conditions for obtaining a good seal; for example, PVC
liner can be effectively sealed to PVC pipe using the appropriate solvent to
meld the materials together.
Most manufacturers offer standardized engineering designs for (a) seals made
in the plane of the liner, and (b) boots to be used around penetrations. If
inlet or outlet pipes are introduced into-the impoundment through a concrete
structure, the seal can be made in the plane of the liner. An example of this
type of seal is presented in Figure IV-21. Here again, a special liner-to-
concrete adhesive system is used that is designed for each liner material.
Anchor bolts embedded in the concrete and batten strips of stainless steel
should be used to secure the liner to the concrete. Mastic should be used
around the edges of the liner material to effect a complete seal.
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. Where reinforced
369 i
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Lining
V* 1" Short Segments of TL304
Stainless Steel Bun Joined Bars
With Bolt Anchor Studs 6" 0/0 (see note)
Mastic
Pipe
Concrete Collar or Structure
Lining to Concrete Adhesive System:
8" Minimum for Asphalt Panels
3" Minimum for PVC
6" Minimum for all other Linings
NOTE:
For asphalt panel linings, pertuxuon driven studs
thru 2" min. diameter * '<6" thick galvanized metal
discs at 6" 0/C encased in mastic may be substituted
for anchor shown
Figure IV-21.
A commonly used flange type seal around penetrations (Kays,
1977).
membrane liners are being installed, manufacturers sometimes recommend
that boots be constructed of unreinforced liner of the same type as that being
installed. This allows the slightly undersized boot to be stretched over the
appurtenance to assure good physical contact and allows some expandability in
case the adjacent liner stretches due to settling. The boot is slipped over
the pipe after the main piece of the liner has been cut and fitted around the
base of the pipe. The proper adhesive is applied between the pipe and boot
and a stainless steel band fs placed around the boot where the adhesive has
been applied between the pipe and boot. The base of the boot is seamed to the
main part of the liner using the same adhesive system and methods used to make
the field seams. Boots should be checked prior to installation to insure 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 IV-22.
It is important to assure that no "bridging" occurs in the liner material
where angles are formed by the subgrade. Bridging is the condition that
exists when the liner extends from one side of an angle to the other, leaving
•170 "
-------
Lining
Lining to Lining Adhesive
Pipe Boot
" Wide Stainless Steel Band
Metal to Lining Adhesive
Wide (see note)
Stable Compacted Substrate-
Concrete, Gunite or Asphalt Concrete
NOTE:
Clean pipe thoroughly at area of
adhesive application
Figure IV-22. An examp.le of a technique for
the boot type method (Kays, 1
sea
ling around penetrations using
^
i t
a void beneath the liner at the apex of the angle. Bridging occurs most often
at penetrations and where steep sidewalls meet the bottom of the impoundment.
Particular attention should be directed to keeping the liner in contact with
the subgrade at these locations and that it be 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 liner material or
seams.
Special considerations must be given to instances where dynamic head is going
to be dissipated onto the liner. This would occur, for example, at an inlet.
structure where water will be flowing into the impoundment. Generally, a
splash pad should be constructed by placing one or more additional layers of
liner at the point of impact to help absorb energy resulting from the inflow
of water. A concrete pad or a filter fabric geotextile may also be used under
the Une'r to insare further mechanical stability (Figure IV-23). If water
is to be discharged into an impoundment,- often the design will specify a
sluice type trough which can also be constructed out of liner material and
placed on top of the main liner (Figure IV-24). This will help prevent
371
-------
INLET PIPE
CSPE SHROUD WITH I
STAINLESS STEEL CLAM?
30 MIL L/NEH
BATTEN ANCHOR
SYSTEM
BOLTS ON APPROX.
• 12" CENTERS—>
ft -ft *i
SEE DETAIL A
CONCRETE PAD
BATTEN: /"OR RAM-SET
1. REDWOOD /
2. STAINLESS STEEL
3. ALUMINUM
1' x '/•'
30 MIL LINER A BUTYL TAPE-
CSPE ADHESIVE
45 MIL
LINER
i DETAIL A I
INLET SPLASH PAD
NTS
• CONCRETE PAD
BR 700 CONTACT
ADHESIVE
Figure IV-23. Splash pad construction using a concrete subbase. (Source:
Burke Rubber Company)
damage to the main liner resulting from any abrasive materia
present in the water-discharged into the facility.
which might be
If gases are expected to accumulate under the liner or large expanses of the
sides of an impoundment will be exposed to high velocity winds, gas vents
should be installed. Gas vents should be located just: below the berm on the
freeboard area.
If an aeration system is part of the facility design, appropriate precautions
should be taken to insure that the liner surrounding the structure remains in
position. This is usually accomplished by using a mooring pad placed on top
of the liner for a floating aerator. The mooring pad also prevents mechanical
damage to the liner immediately adjacent to the aerator. It is recommended
that an additional layer of liner material be placed between the mooring pad
and the main part of the liner. When a fixed aerator is used, the liner
material may cover the foundation pad and an additional pad can be poured
over the liner. Here again, an additional layer of liner material is sand-
wiched between the pad and liner. Permanent anchors should be placed ten feet
apart in a circle approximately 20 feet from the base of the aerator to
prevent the liner material from being lifted from the subgrade. Figure IV-25
shows some typical design details for aeration structures.
372
-------
Figure IV-24.
fOU
Sluice type trough constructed of liner material. The easies
method of placing inlet and outlet pipes into a membrane line'
lagoon is over the top of the berms, using a protective line
to contain the discharge, thus protecting the main liner. Thi
fewer protrusions- that are designed into a lining, the easiei
it is to install and maintain both the liner and the piping,
A double layer of liner material over the liner at the inlet
may also be sufficient, as opposed to the prefabricated trough
illustrated (Source: B. F. Goodrich).
Protective oad for
fixed aerator •
Additional layer
of membrane
"• H / H Memorane liner
V-'Jr.Tr.'-.r/ yTTYlj /
..
.-.ifiV.•.•.:•:•.•.•:•/.;•—Jr \
Additional memorane
liner under oad-
r- Concrete mooring pad
P"l \ to nold floating aerator
Foundation
Radius on all
top corner]
Figure IV-25. Typical design details for floating and fixed aeration systems
(Kays, 1977).
Personnel reviewing the design or performing quality control functions for a
liner installation should be familiar with the liner manufacturer's recommend-
ations regarding all facets of the material's use and installation. This
Includes everything' from the liner's compatibility with the material being
stored to recommendations regarding specific adhesive systems and special
seaming instructions around penetrations.
Note: See Chapter 5 for References.
373
-------
APPENDIX V
LEACHATE COLLECTION SYSTEM NETWORK
A leachate collection system generally consists of strategically placed
perforated drain pipe bedded and backfilled with drain rock. The pipe can be
installed in a trench or on the base of the landfill. The system can be
installed either around the perimeter of the landfill or underneath the
landfill in the form of a complex network of collection pipes. The latter
is utilized when the areas in/olved are very large and/or the allowable
head buildup is small (see Section 5.6.3, "Transmissivity"). The collec-
tion system is drained to a sump or a series of sumps from which the leachate
is withdrawn. This Appendix discusses the layout, sizing, installation, and
selection of pipe material for leachate collection systems. A series of
charts and tables are presented for use in the design and analysis of such
systems.
V.1 Flow Capacity
As indicated in Chapter 5, the spacing
influence the maximum head of leachate
uniform rate of leachate percolation to a
of the medium through which the leachate
of leachate collection pipes will
on the oase of the fill, given a
saturated fill and the permeability
is withdrawn. Figure 5-26 can be
used to select the required pipe spacing given an allowable leachate head over
the base of the landfill. Figure V-l 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 V-2 can be used to select pipe sizes.
The configuration of the collection pipe network varies, depending on the head
allowed over the landfill base liner: the greater tne allowable head, the
greater the pipe spacing. For maximum control of lateral migration, the
leachate collection system should extend completely around the perimeter of
the site to provide absolute control of the level to which leachate can rise
on this critical boundary.
An interior grid system becomes necessary if the leachate head on the base of
the fill must not exceed a specified value. The slopes and spacing of the
interior grid pipes are controlled largely by a base slope of a minimum
of two percent. Placement of a layer of permeable material over the base of
the fill, coupled with the use of an interior collection pipe grid, may be
necessary in extreme cases where the development of a leachate head cannot be
tolerated.
374
-------
120
3 4
Percolation, in incn«i p«r month
Where b-wicHh o1 Oreo contributing
to leachate collection pipe
Figure V-l. Requ)red cap.clt, of 1eachate C0,,ea1on pjpe_
375
-------
aFPt
^
V 1.
M \
^
k, , • 1 1 '
2£=
•0
c
a
O
to
c
1/1
ro
OJ
Q.
0
u
OJ
4->
5
s
ai
CT!
376
-------
V.2 Structural Stability of Pipe
V.2.1 Introduction
Pipes installed at the base of a landfill to collect and conduct leachate t
withdrawal wells can be subjected to high loading of waste fills, which a
rise several hundred feet above the pipe.
Leachate collection pipes beneath landfills generally are installed in one o
two conditions: (1) a trench condition or (2) a positive projecting condition
These installation conditions are shown on Figure V-3. In the analysis of th
structural stability of a pipe under the imposed loading, the pipe is con
sidered either a rigid or flexible conduit. Examples of rigid conduits ar
concrete and cast iron pipe. Plastic and fiberglass pipes are examples o-
flexible pipe. Because the landfill environment is highly corrosive, pipi
materials generally selected for use in leachate control systems are plasti<
or fiberglass due to their relatively inert properties with respect to typica
municipal leachate. This section discusses the structural stability ol
flexible pipe in landfill applications.
V.2.2 Loads Acting on Pipe
Loads are determined for one of two conditions: 'a trench condition or a
positive projecting condition.
V.2.2.1 Trench Condition (Figure V-3)
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 :f tne total vertical pressure
on the pipe are computed separately and then adced to obtain the total vert-
ical pressure acting on the top of the pipe. "^e refuse fill is assumed to
develop a uniform surcharge pressure, qf, at 're base of the refuse. The
magnitude of qf is given by the expression: •
qf =
where:
qf = vertical pressure at the base of the refuse due to waste fill
(Ibs/sq ft)
• of a unit weight'of the waste fill (Ib g/cu ft); values range between
45 and 65 for municipal waste with soil cover
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:
377
-------
0
0, .5
oc
a
»*.
° a, *
o 5
cJ
g -JJ
« '3 -°
B
CO
10
en
0)
ON
ON
oi 01 *.
TRENCH CO
0
s
o
K
o
UJ
o
£
'
'« « n ,, „ „
3 *" x" «r" > *
' •« M
— •• u
»« CD CD X Zi,
in
o
en
c
•o
c
o
C
O
c
o
O
o
X
o
UJ
IT3
•M
01
O)
a.
a
o
u
o
-------
The term CuS, a load coefficient, is a function of the ratio of the depi
of the trench, 2, (measured from the ground surface to the top of the pip<
to the width of the trench, 8-^-, O i\'> ^
0-02 0-03 0-05 0-07 0-10
LOAD COEFFICIENT,
0-20 0-30 0-50 0-7D HM
Values of load coefficient CM (trench uniform surcharge)
Figure V-4. Projecting condition - pipe load coefficient (Clarke, 1968)
379
-------
The product of K u1 is characteristic for a given combination of backfills in
natural (in place) soil. Maximum values for typical soils are presented in
ASCE Mani/al of Practice, No. 37. Those values of K M' representing soils irifl
which flexible pipes are likely to be installed are: ~
Type of soil
Sand and gravel
Saturated top soil
Clay
Saturated Clay
Maximum value of
0.165
0.150
0.130
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:
aV2 = (Bd)(w)(Cd)
where: u = unit weight of trench backfill (Ibs/cu ft).
The term Cd is a load coefficient which is a function of the ratio Z/8d
and the friction between the backfill and sides of the trench. It may be
computed from the following -equation or obtained from Figure V-5.
Cd =
1,e-2Ku'(Z/Bd)
2KU'
where the terms are as defined above.
The- total vertical pressure is equal to:
The force per unit length of the pipe is equal to:
W » ov Bc
where: W = force per unit length of pipe
Bc = outside diameter of pipe
V.2.2..2 Positive Projecting Condition (Figure V-3)
This condition is assumed to exist whenever the top of the pipe is at or above
the level of the refuse base. 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
380
-------
COEFFICIENT C' = 0.150 max. for saturated top soil
VforKv! '= 0.130 orrfma«/»"«» <•—«---
0.130 ordiaao' max for clay
for Zji' =,0.110 max. for saturated clay
Valuta of load coefficient Ca (bac* fill)
»9ur. »-5. Trench Condition - Pipe Load Coefficient (C1.rt.. 1968).
381
-------
be small compared to the pressure due to the fill, the vertical pressure on
the top of the pipe can be assumed to be equal to the unit weight of the
refuse fill multiplied by the distance from top of fill to top of pipe^
thus: 9
av • (wf)(Hf).
V.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 increas-
ed vertical stress to be used equals:
(ffv)design
12
12-1,
Xfa
(Vactual
V.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:
n
"
El + 0.061
where:
= horizontal and vertical deflection of the pipe (in)
De =
W =
r *
E =
£' =
a factor, generally taken at a conservative value of 1.5,
compensating for the lag or time dependent behavior of the
soil/pipe systems (dimensionless)
vertical load acting on the pipe per unit of pipe length
(Ib/in)
mean radius of the pipe (in)
modulus of elasticity of the pipe materials (psi)
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%)
382
-------
,< = bedding constant, reflecting the supoort the pipe receives f^c
the bottom of the trench (aimensionless) (a conservative yak
general ly taken 0.10)
I = moment of inertia of pipe wall per unit of length (inVin)
for any round pipe, I = t^/12 where t is the average thick
ness ( in) „
The equation can be rewritten to express pipe deflection as a decimal fractioi
of the pipe diameter, 8C, and to relate it to the vertical stress on tne pip<
as follows:
W a (_Ay) (El + O.OSlE'r3)
Be " " " (Bc)( DeKr3 ).
Solutions to this equation are shown graphically in Fig. V-6 where the quant-
ity a v/(ay/8c) has been plotted against the passive soil modulus £' . The
relationship between av/(Ay/Bc) and E' has been shown for four plastic
pipes: 4 and 6-inch Schedule 40 and 4 and 6-inch 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 EI=0. This would reoresent a
relationship between Jv/(iy/3c) and £' if the stiffness of the pipe is
neglected .
In addition to using the chart to cneck the adequacy of a given pipe, the
chart can be used to determine the necessary value of EI/>3 which the pipe
must have for given values of Jmax/(iy/Bc) anc -.' . Although it is custom-
ary to use either 300 or 700 psi for the value if the modulus of passive soil
resistance, it should be noted that the modules of elasticity of a coarse
grained soil (sand or gravel) increases with increasing pressure (or depth in
the ground). Thus, it snould be expected that tne modulus of oassr/e soil
resistance also would increase with increasing pressure or depth of fill.
The term El in Spangler's equation reflects the pipe's contribution to the
total resistance to deflection under load offered by tne pipe/soil system.
This term, known as the pipe's Stiffness Factor, is related to the oipe's
behavior under parallel plate loading as per ASTM 0 2412, External Loading
Properties of Plastic Pipe by Parallel Plate Loading, by the following expres-
sion:
El = 0.149r3(F/Ay)
where:
E, I and r are as previously defined
F = the recorded load (lb/ linear inch) required to produce a pipe
deflection ay
Ay = the pipe's deflection (in).
383
-------
1300
1200
1100
1000
900
- 800
i*
a
cc
700
600
500
400
300
200
100
Assumed. D, = I. 5
K • O.I
Figure V-6. Selection of Pipe Strength
* (ASCE, 1969)
384
-------
Minimum values of the term F/ay, called Pice Stiffness, are set according tc
Pipe OR (dimension ratio) by the ASTM PVC Sewer Pipe Specifications 0 3033 ana
0 3034. The OR represents the ratio of the pipe's average outside diameter to
its minimum wall thickness. Thus, for each OR there is a corresponding
minimum specified value of F/&y.
The above expression for El can be substituted into the previous equation for
deflection to obtain the following:
Jv = (Q.149F/Ay) + 0.061E1
Uy/Bc) o7<
Solutions to th's equation can be made on a graph similar to Fig. V-6 where
the quantity av/(Ay/8c) is plotted against the soil modulus E' for several
values of F/ay.
V.2.4 Buckling Capacity
The capacity of a buried plastic drain pioe to suooort vertical stresses may
be limited by buckling. Estimates of the vertical stresses at which buckling
of the 6-inch Schedule 4Q PVC oipe (the most flexible of the four pioes shown)
will occur are indicated oy trie curve in Fig. /-6. For the four pipes shown,
buckling would not be a controlling factor. However, it could be a controll-
ing 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.
V.2.5 Compressive Strength
The capacity of the pipe to support vertical stresses .ray be influenced by the
circumferential compressive strength of the pioe. ~he designer or reviewer
should secure up-to-date information on circumferentia1 :ompressive strength
characteristics from the manufacturer of the type of ~ e proposed for use.
V.2.6 Construction Loadings
A pipe correctly designec to withstand loading frcm a high fill can fail from
loading received during construction. Although only a '> act ion of a station-
ary wheel or tracked vehicle load applied at the grounc 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 generally
considered to have a 1.5 to 2.0 multiplier effect over stationary loading.
In general, equipment should not cross leachate collection drains installed in
trenches with shallow cover or in projecting installations. When equipment
must be routed across a drain, impact loadingjcan be minimized by mounding
material over the pipe to provide a vertical separation of 4 feet between the
loaded surface and the top of the pipe.
385
-------
V.2.7 Procedures for Selection of Pipe Strength
The procedures used to select the proper strength pipe are illustrated in t
following examples:
Trench Installation (See Figures V-4 and V-7)
Given: Z = I1-8" Hf = 100 feet waste fill
Bd •= I1-6" u>f = 50 pcf
u » 110 pcf
pipe diameter = 4"
Determine: Required pipe strength/schedule.
Step 1 - Determine the maximum vertical pressure c'v (psf) acting on the
top of the pi.pe.
Ku' « 0.19
Z 1.67
= 1.11
qf = (wfjHf = 100 (50)
= 5000 psf
8d 1.5
from Fig. V-4, CuS = 0.64
Fig. V-5, Cd = 0.9
then- % = (J(Bd)(Cd) * l'qf)(CuS)
= (110)(1.5)(0.9) * (5000)(0.64
= 3348 psf = 23.3 psi = Jv max
386
-------
«M
h-
— Wo»t« fill
r— Excavation tubgradt
6" min. —
/**?
V£ -
^*y •
\
V.
I«' •
~-7
)
S
, 2'
•4 PVC
N
/
\ I
pip«, p«rforat«d
r2'
Excavation «lop«
5'
PVC p(p«) parforated
PROJECTING INSTALLATIONS
Drain roc*
4 PVC pip», p«rforat«d
TRENCH INSTALLATION
Figure V-7. Typical leachate collecti
387
on drains.
-------
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 t
0.1.
o
Step 4 - Determine the quantity v max ^ where crv max is in psi.
VBC
From Fig. V-6 the following information is obtained.
av max £'
ay/Bc &y/Bc 300 700
0.05 466 4" Sen 80 4" or '6" Sch 80
adequate adequate
0.1 233 4" Sch 40
or
6" Sch 80 Any pipe
adequate
Positive Projecting Installation (See Figures V-3 and V-7)
Given: 2, = 6"; other parameters given as in example above
Determine: Required pipe strength/schedule
Step 1 - Determine the maximum vertical pressure av(psf) acting on the
top of the pipe.
av = WfHf +"?} = (50M100) + (HOMO.5) = 5055 psf = 35.1 psi = Jv max
Steps 2, 3, and 4 as above
From Fig. V-6 the following will be obtained.
ffv max E'
Ay/Bc
0.05
0.1
ay/Bc 300
702 none
acceptable
351
4" Sch 80
adequate
700
none
acceptable
4" Sch 40
or
6" Sch 80
adequate
Note: See Chapter 5 for References.
,388
-------
APPENDIX VI
SYSTEM ANALYSIS AND OPTIMIZATION OF SOIL LINER DESIGN
The purpose of the design is to achieve a seepage below the liner, lower thc
a certain critical value, Qp. The analysis of the system can be done usir
different procedures. As an example, we will use the McWhorter ana Nelsc
(1979) analysis. For convenience, we will preserve the nomenclature used t
the authors. A schematic representation of the flow system is presented i
Figure VI-1.
In the subsequent analysis, it is assumed that tne geometry of the system i
unchanged m time, i.e. the aepth of tne free waste fluid, y, the Jeotn of tn
solid waste, D^, and tne depth of tne underlying undisturaed so • 1 , 2--, ar
given. The depth of tne soil liner DI is variable. The permeaoi1:ty of tn
solid waste, K^, and the permeaoility of the isotropic, nomogeneous underly
ing soil Kf are also given. The permeability of the soil liner .<; is variablt
and can be optimized vis-a-vis the depth of tne soil liner 0] to result in ,
seepage rate lower than qp. Otner parameters .vhich will be found in th«
analysis have the following meaning:
n = soil porosity, equal to volumetric mo'sture content when the soil is
saturated.
*, = initial volumetric moisture content •:: tne underlying soil.
h,j, ar, and * = parameters experimentally r"ound rvhen determining tne
moisture characteristic curve (,'CC) . The MCC is the
relation oetween tne magnitude of suctjon applied and tne
equilibrium moisture content corresponding to tne given
negative head.
h(j = displacement pressure or air-entry pressure (negative). The
threshold suction needed to break soil capillaries and allow water
drainage. For most soils it is between -50 cm and -150 cm. The
more clayey a soil the lower (the more negative) the h
-------
":- ^ WASTE FLUID "Z
SATURATED
SOLID WASTE
K - K,
SOIL LINER
K = K
UNDISTURBED SOIL
K = K
f
PHREATIC
SURFACE -
AQUIFER
K- Ka
IMPERVIOUS
Figure VI-1. Sketch of the flow system.
H.
A = a shape factor of the MCC. In the present analysis, it was assumed
equal to unity.
hc = effective capillary drive = hd
hc = 1.25 hd.
Since x = 1 in this analysis,
The flow event is visualized as occurring in three stages:
Stage 1 - The infiltration of the fluid into the underlying, originally
unsaturated soil. In the wetted region the same soil may or may not be
fully saturated. • - "
390
-------
Stage 2 - This stage starts as soon as the wetting front reaches •
groundwater or its capillary fringe and a groundwater mound is be'
formed: Stage 2 continues until the mound reaches the base of t
1iner.
Stage 3 - Saturated flow throughout the whole system.
It is clear that the slower every stage is developed the better suited t
system is to confine wastes. If, for instance, Stage 3 is reached the succe
of the system in control ing contamination will rely heavily on the ability
different strata (soil liner and underlying soil) to chemically bind t,
contaminants. If fresh waste fluid is continually added to the waste dispos
site, the strata will reach their saturation. In the long run the systi
sketched in Figure VI-1 will have the same composition and concentration <
the fresh waste fluid. The limiting concentration at a well will be
fraction of the fresh waste fluid concentration due to dilution by the incon
ing fresh groundwater stream.
At the present level of knowledge, we have to prevent the occurrence o
Stage 3 and even Stage 2. Accordingly, we will analyze numerically some c
the important parameters during the infiltration towards the groundwate
(Stage 1).
Example of Numerical Analysis for Stage 1
The advancement of the wetting front between the soil liner/underlying soi
interface and the original groundwater level can occur either as a saturate!
or as an unsaturated flow, depending on the geometry and flow properties 01
the traversed strata. For our purpose, the less saturated the flow th«
better, since the seepage rate is proportional to the degree of saturation,
Consequently, it is important to design the system in such a way as to promote
unsaturated flow during infiltration.
The flux across the sequence of solid waste-soil liner is given by the equa-
tion:
(y + Ot •*• 0]) -hf / ])
9 = —n FT:
_^, 4. -^,-L,
where hf is the pore-water pressure in the wetted underlying soil during flow
with all other terms already defined (Equation 10, McWhorter and Nelson,
1979).
For unsaturated flow to occur, hf has to be more negative than the air-entry
pressure, h
-------
Assuming the optimization of tfce system can be achieved by varying D] and
K], the depth and the permeability of the soil liner, and assuming the permea-
bility of the underlying soil kf is equal to 10~5 cm sec'1 and its air-entry^
pore-water pressure, hd, is equal to -50 cm equivalent water, equation 2™
becomes:
Dt . 10-5 + 50 < ,0-5 g. 0, (3)
The values of the left hand side of the inequality expressed in cm, are
presented in Table VI-1 for different y, D^, and «t levels.
TABLE VI-1. LEFT HAND SIDE OF EQUATION 3, in cm
y.
feet
3
60
feet
1
20
1
20
io-4
169
690
1906
2428
«t (cm sec"1)
10-5
141
14]
1879
1879
io-6
-133
-5351
1604
-3619
The right hand side of the inequality (Equation 3} expressed in cm, is pre-
sented in Table VI-2, for different combinations of k] and D], the perm-
eability and the depth of the soil liner.
TABLE VI-2. RIGHT HAND SIDE OF EQUATION 3, in cm.
cm sec'1
io-6
10-7
10-8
1
275
3,023
39,500
feet
6
1,678
18,123
182,880
The condition of unsaturated flow hf
-------
In Table VI-3, we present the system requirements which will generate •
best observance of the condition hf 1500. The same requirements are satisfied by D] = two
feet and a permeability K] = approximately 3 x 10"7 cm sec'1. Considering
both engineering and economic conditions, the designer will be able to optim-
ize the two parameters.
Let us consider that the underlying soil has different properties than the
ones assumed in the previous example. Suppose now Kf = 10"6 cm sec -1
and hd = -150 cm. This set of data should correspond to a more clayey soil.
The new working equation generated for this case will be:
ot - 10-6 + 150 < 10-6 - D] (4)
Paralleling the previous example, the values of the left hand side of the
inequality are presented in Table VI-4.
i " 393
-------
TABLE VI-4. LEFT HAND SIDE OF EQUATION 4. in cm.
y
feet
3
60
Ot
feet
1
20
1
20
10-4
272
845
2009
2583
«t (cm sec'l)
TO'5
269
790
2006
2528
10-6
241
'241
1979
1979
The right hand side of Equation 4 -s presented in Table VI-5.
TABLE VI-5. RIGHT HAND SIDE OF EQUATION 4, in cm.
cm sec"1 feet
10'6
10-7
10-3
0
275
3,020
0
1,646
18,107
The conclusion to be drawn from the first step of calculations is that unsatu-
rated flow in the underlying soil is secured when the ratios K]/Kf and
«t/Kf are very low. This can be seen from tne inspection of Equation 2.
The condition of unsaturated flow hf
-------
q = 3 inches/year = 2.4 x 10~7 cm. sec'1. Assuming, together with t
figure, that the two important properties of the underlying soil are: K1
10~5 cm sec"^ and h
-------
By comparing the figures from Tables VI-6and VI-7, one should be able to
decide about the particular soil liner permeability K] required. For this
particular case, one can see that the choice will be quite difficult since
it may be impractical to compact the soil to yield the low range of permeabil-
ities indicated in Table VI-7.
The inspection of Equation 6 reveals that the required permeability is con-
trolled by the magnitude of y and D^. The term -105.4 in the left hand
side of the equation is not very influential in determining the k] value.
Not so, when y and Dt are relatively smal . In this situation the term
[n
-------
soil becomes critical in generating a low permissible flux,
situation a deep soil liner of low permeability is required,
tion may not be economical.
since for th
and this situ
For the situation in which the condition of unsaturated flow is not observe-
i.e. when hf i hj, the downward movement in the underlying soil will occ
as saturated flow. According to McWhorter and Nelson (1979), such a situatii
will be observed, for instance, for the following set of data:
y * 10 feet
Ot = 3 feet
Dj * 1 foot
Kt a 10"4 cm sec'1
K] = 10~8 cm sec'1
Kf = 10"7 cm sec'1 .
hd < 0
Assuming hc = -50 cm, the flux can be calculated, using the equation (Equa-
tion 22 from McWhorter and Nelson, 1979):
q = Kf
(L
0] -nc)
(L > Dt£f + 0] I!
Kt \;
The calculated flux
distance L equal to
below the soil liner when the
10 m below the liner, will be
wet t i ng front
1.13 x TO'7 cm
i s
sec
at a
If the soil porosity, n, is equal to. 0.4 and the initial volumetric moisture
content 9, equal to 0.25, the relationship between time t and L can be
expressed, using:
(8)
n-e-
+ Dl
ln
L +
y
y +
+ °t
Dt -
. * I
H 0]
- hc
hc
)
= t
For the set of data considered, the time t corresponding to L = 10 m is equal
to 38.3 years. Since the flow was saturated and the volume occupied by the
incoming waste effluent accounts for 15% of the soil bulk volume (n- &j =
0.15), the length of the waste effluent column saturating the underlying soil
is equal to 150 cm. The ratio of 1.50 cm over 38.3 years results in an average
q equal to 1.24 x 10~7 cm sec'1, which checks well with the figure calculat-
ed using Equation 7.
397
-------
The presented numerical example has many limitations and the designer should
be aware of them: _
a. The real system to be analyzed may have variable dimensions in time,
for instance if the incoming waste accumulates in the waste disposal
site.
b. Flow properties of all traversed strata can be altered in time.
c. Some of the characteristics of the underlying soil (h^ and \).'
which have been discussed in this presentation can be very sensitive
to minute soil intrinsic property changes. Thus, an apparently
homogeneous underlying soil can have, at different locations along
the vertical flow direction, different h^ and \ values.
d. The temporary physico-chemical retention of :ne potential contami-
nants present in the original waste fluid has been disregarded in
this analysis. Most of the experimental work on miscible displace-
ment performed so far refers to saturated flow. In unsaturated
condition, the processes of diffusion, hydrodynamic dispersion,
adsorption, phase cnange of chemical species, etc., are expected to
be connected in a more complex manner.
it considers the
in most instances.
The most important merit of the presented analysis is that
flow to be unsaturated wmcn is a reality in the field, i
The analysis for design can be carried out using other procedures. If the
system is more complicated than the one presented n our example, advantage
can be gained by using a computer assisted 'numerical analysis.
Note: See Chapter 5 for references.
398
-------
APPENDIX VII
CASE STUDY ANALYSIS METHODOLOGY
This Appendix illustrates the case study method of analysis for developi
project costs, and possibly other project components. Depending upon the ty
and size of project envisioned, the case study method can range from- a fair
simple analysis to a very complex procedure. Our example case study is
straightforward and simple illustration of the technique.
Case Study of Community X for a Waste Impoundment
A site within Community X has been chosen as the location of a hazardous wast
impoundment facility, which is to serve the surrounding Tietropol itan ars
containing several industrial concerns. T'ne site is flat and the facility ha
the design criteria and parameters shown in Table VII-1.
TABLE Vn-1. DESIGN CRITERIA AND PARAMETERS
Item Criteria value
Flow
Average design flow 50 gpm (4000 ft^/day)
Pond
Minimum requirement 120 acres
Cell size 15 acres
Numoer of eel Is 3
Total design area 120 acres
Pond depth
Freeboard 2 feet
Minimum (for liquid seal) ' • 1 foot
Storage 4 feet
Total design depth 7 feet
Embankments
Slope 3:1
• Top width (minimum) 8 feet
Liners
Primary 45 mil reinforced CSPE
Secondary 30 mil reinforced CPE
Monitoring wells • . 10
Life ....-- 20 years
399
-------
The engineer for the facility has determined that thin polymeric membrane
liners are necessary to contain the wastes adequately. That decision
effected by the inadequacy of the native soil and the unavailability of
nearby suitable clayey soil for construction into a liner. The wastes to be
impounded are not radioactive. The literature has revealed that the wastes to
be impounded do not adversely affect the reinforced • chlorosulfonated poly-
ethylene liner nor do they adversely affect the chlorinated polyethylene
liner. Compatiblity testing accomplished during the design phase had con-
firmed the above conclusion. The owner and the engineer have decided to use a
double liner system with the following configuration. A 30 mil reinforced CPE
liner (secondary liner) is placed over a graded compacted native soil. On top
of the CPE liner is a three foot, layer of moderately compacted native soil
which contains the perforated pipe drain system. The perforated pipe trench
is backfilled with filter sand or gravel. A thin soil layer is then placed
over the three foot layer. A 45 mil reinforced CSPE is placed on top as the
primary liner. The monitoring system consists of one well per cell located
near the lowest point of the underdrain system plus two groundwater observa-
tion wells perforated in the native soil subgrade located down gradient of the
impoundment.
Due to possible wave action in the impoundment facility during adverse weather
conditions, two feet of freeooard is provided. Impoundment embankments are to
be constructed with 3:1 slopes from material obtained near or on the site. To
minimize erosion of these earthen embankments or dikes, a vegetative and/or
rock cover may be utilized. A minimum top width of eight feet is required.
Particulate emissions from impoundment areas will 5e minimized by maintaining
solids in a slurry or liquid state. Total design depth of the pond is the sum
of the required freeboard, the mimnurn storage deptn necessary to maintain the
contents in a liquid state, and the design storage ^epth. In order to main-
tain operation flexibility and maximize efficiency and effectiveness, the
impoundment is divided into smaller cells. Each ce:' has an area of 15 acres.
In case of leakage or maintenance operations, liquic wastes can be pumoed to
adjacent cells. The ability to drain individual cells provides flexibility in
control of the liquid depth of a cell thereby increasing operation relia-
bility.
Table VII-2 presents the capital costs for the waste impoundment facility.
Table VII-3 shows the operating costs and Table 711-4 presents the total
annual costs of the facility.
400
-------
TABLE VII-2. CAPITAL COSTS FOR WASTE IMPOUNDMENT FACILITY
Cost3,
Component thousands of dollars
Construction
Excavation 630
Smoothing and clearing 114
Drainage and collection 165
Linerb 10,694
Monitoring system0 120
Subtotal 11,723
Impoundment closure
Final cover 30
Revegetation 120
Monitoring 48
Suototal 198
Construction contingencies
Engineering, administrative,
legal and permit costs (25%) 2,980
Total Impoundment Capital Cost 14,901
aBased on prices quotes from August, 1980.
^Primary liner and secondary liner plus installation. Based
on S0.35/sq.ft. reinforced chlorosulfonated polyethylene and
0.70/sq. ft. CPE.
cAssume 10 wel1s.
TABLE VII-3. OPERATING COSTS FOR IMPOUNDMENT FACILITY
Item
Impoundment
Power
Operation and maintenance
Total
Annual cost
S/yr
-
24,880
116,120
141,000
Unit cost
$71,000 gal
0.024
0.11
0.13
401
-------
TABLE VII-4 ANNUAL COSTS FOR IMPOUNDMENT FACILITY
Component Annual costs
Capital costs3$1,995,000
Operating costs 141,000
Total $2,136,000
aTwenty year amoritization at 12 percent interest - capital
recovery factor = 0.13388.
402
-------
APPENDIX VIII
SUGGESTED STANDARDS FOR REPRESENTATIVE FLEXIBLE POLYMERIC MEMBRANES
AVAILABLE IN OCTOBER 1982
In view of the lack of accepted standards to cover currently available flex-
ible membrane materials for lining waste disposal impoundments, suggestec
standards for representative membranes currently available (October 1982) are
presented in this appendix. The values are preliminary and subject tc
change. They are based largely upon the properties and tests discussed in
Table 3-7 in Chapter 3 and reflect some of the current efforts to develop
standards.
These taPles of values snould not be used to select materials. Selection, as
indicated in Chapter 3, snould be oased u..n factors of compatiDiii ty, dura-
bility, etc. They are intended to Ge used as a means of assuring :ne quality
of the lining material tnat is installed in tne waste disposal facility and of
assuring that the quality of tne material is tne same as was observed in the
compatibi1i ty tests.
The'standards present values for different properties wnich can characterize
the membranes currently on tne market. By themselves, these standards are not
adequate to predict product performance, nor can :ney oe used for engineering
design purposes. For example, the low temperature resistance numbers repre-
sent qualities measured after a few minutes exposure at a given temperature
and should not be interpreted or extrapolated :°to installation temperature
qualities or comparisons. Correlations of specific properties and tests witn
field performance of lining materials have not been estaolisned, out the
results of the tests indicate the quality of the specific material under
test.
VIII. 1 GENERAL REQUIREMENTS FOR MANUFACTURE OF FLEXIBLE POLYMERIC MEMBRANES
Membranes shall Oe 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 urn 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.
The resultant membranes shall be free from dirt, oil, foreign matter,
scratches, cracks, creases, bubbles, pits, tears, holes, pinholes, or other
403
-------
defects tnat may affect serviceaDi1ity and snail 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 wasteM|
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 established at this time and tests are underway to
resolve this question.
VIII.2 SUGGESTED TEST METHODS AND REQUIRED PROPERTIES FOR REPRESENTATIVE
LINERS
Suggested methods for testing flexible polymeric membranes for acceptance and
quality control and required values for properties of representative liner
materials are presented in the following seven tables:
VIII-1. Suggested Test Methods for Testing of Flexible Polymeric Membrane
Liners.
VIII-2. Titles of ASTM Test Methods Used in Memorane Liner Specifications.
VIII-3. Suggested Standards for Flexiole Memorane Liners Without Fabric
Reinforcement - Crosslinked Memoranes.
VIII-4. Suggested Standards for Flexible Membrane Liners Without Fabric
Reinforcement - Thermoplastic Membranes.
VIII-5. Suggested Standards for Flexible Membrane Liners Without Fabric
Reinforcement - Partially Crystalline Memo^anes.
VIII-6. Suggested Standards for Faerie-Reinforced Flexible Membrane Liners -
Thermoplastic Coatings of CPE, Nitrile Ruooer - PVC, EPDM, and
EIA.
r r t
I i- I
Suggested Standards for FaD~ic-Reinforced Flexible Memorane Liners -
Thermoplastic Cnlorosul fonated Polyethylene (CPSE).
For quality control purposes, it is suggested tnat random samples be taken
from each 10,000 square yards of sheeting; however, a minimum of five samples
for quality, control testing snould be taken from each job. Each sample should
be three by six feet: and snould include a factory seam if the membrane re-
quires factory fabrication. The minimum tests that should be performed for
quality control purposes are those trat are listed under mechanical.proper-
ties.
Table VIII-1 presents all of the suggested, test-methods arranged by type of
membrane and by analytical properties, mechanical properties, and tests of the
effects of environmental and aging conditions on properties. The types of
polymeric membranes are:
404
-------
1. Crossl inked memoranes without faerie reinforcement.
2. Thermoplastic membranes witnout faoric reinforcement.
3. Crystalline membranes without fabric reinforcement.
4. Fabric-reinforced membranes wnich include both membranes with cross
linked coatings and those with thermoplastic coatings.
Note: No fabric-reinforced membranes with crystalline coatings are current!.
available in thicknesses of 20 mils or greater.
Table VIII-2 lists all of the ASTM tests that are suggested, showing theii
titles and whether they are specifications. One of the test methods (ASTP
01239) was recently discontinued; nowever, it can be used as a test for the
resistance of plastic sheetings to extraction.
Table VIII-3 presents the suggested standards for membrane liners without
fabric reinforcement that are Dased upon cross!inked compounds. Membranes of
the following polymer types are included in this table: butyl rubber,
crosslinked chlorinated polyetnylene, epicnlorohydrin rubbers, ethylene
propylene runoers, and neoprene. The values listed are for sheetings of 45
mils nominal thickness, wnicn is the intermediate tnicxness for commer-
cially available Tiemoranes of tnis type. For most of the polymers,
-------
thickness. Otner properties sucn as specific gravity, volatile loss, elonga-
tion at yield, elongation at break, modulus of elasticity, dimensional s
bility, low temperature brittleness, resistance to soil burial, ozone
sistance, resistance to environmental stress cracking, and water extraction
can be considered for these specifications to be independent of the thickness
of the sheeting.
Tables VIII-6 and VIII-7 present the suggested standards for representative
fabric-reinforced flexible polymeric membrane liners. Strength values for
these membranes depend upon the fabric reinforcement used. Fabric reinforce-
ment increases tensile strength, puncture resistance and tear resistance, and
reduces shrinkage and elongation at break. Table VIII-6 covers those mem-
branes coated with thermoplastic chlorinated polyethylene, nitrile - polyvinyl
chloride, EPDM, and ethylene interpolymer alloy. Table VIII-7 covers fabric-
reinforced chlorosulfonated polyethylene lining materials. It covers both
standard (potaole grade) CSPE coated membranes 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 memoranes are
equal except for breaking strength, strength of factory seams, 'and water
absorption.
No required values are suggested for seam strength tested in the peel mode nor
by dead weignt test because of trie lack of data. Tnese are, however, con-
sidered to be important tests for assessing adhesion in seams made ootn in the
factory and in the field. Peel ana dead weignt tests are particularly useful
in assessing the duraoility of seams. ASTM Test Methods D413, "Adhesion to
Flexible Substrate (Machine Metnod)" and D1376, "Peel Resistance of Adhesives
(T-Peel Test)" appear to be tne appropriate test methods for assessing peel
strength of liner seams. Also, the effect of soil ojrial on tne peel strength
appears to be needed. Studies are under way to develop tnis information and
it is anticipated the required values for tnese prooerfes will oe included in
tne next edition of tnis Tecnmcal Kesource Document.
406
-------
•A3L£
3UGG£3TcJ -
-'OS "STING JF ,:L;X:3L£ =01 '*Er(IC «E.«BRANE .INERS
'roperties
Anal/cical arooerties
joecif'c gravity
Volatile loss
"ecnanical arooerties
nicuness
1. jverail
2. Coatmg over scrim
Minimum tensile orooerties (in ootn
nacPine ana transverse directions)
1. ireamng 5tr»ngtn of "aor'C
2. ireaung elon^afon or 'aor-:
3. "ensi l« at yield
4. E'ongat :on at yield
3. ireamng 'actor
o. Elongation at area*
7. Stress at 13UI elongation
'•'oou I us if elastic i ty
"ear strengti
*emoranes «it,iout "jor-c reinforcement4
not applicable.
C0n sel vage edge. -• • - ' *•
a(?un 12 incnes per mnute.
*Determination of tne temperature at *nicn iieiioranes exnioit Brittle failure under specifiea impact conditions.
Bend specimen over 1/8 in. manarel after fcur nours at tne test temperature.
^Buried specimen r « 5"-.
407
-------
TABLE VIII-2. TITLES OF ASTM TEST METHODS USED IN MEMBRANE LINER SPECIFICATIONS3
ASTM Numoer Title and pertinent sections
0297-81 Rubber Products - Cnemical Analysis. Section 15-Density; Section 34-Referee Asn Metnod.
0412-80 Rubber Properties in Tension.
0413-76 Rubber Property - Adneslon to Flexible Substrate.
0471-79 Rubber Property - Effect of Liquids.
0518-61 (1974) RuDber Deterioration - Surface Cracking.
0573-81 Rubber - Deterioration in Air Oven.
0624-73 Rubber Property - Tear Resistarce.
U638-80 Tensile Properties of Plastics.
0746-79 Brittleness Temperature of Plastics and Elastomers by Impact.
0751-79 Coated Fabrics.
0792-66 (1979) Specific Gravity and Density of Plastics Dy Displacement.
0882-81 Tensile Properties of Tmn Plastic Snee:mg.
01004-66 (198!) Initial Tear Resistance of Plastic "ilm ana Sneeting.
U1149-31 Kuooer Deterioration - Surface Ozone Cracking in a CnamDer '':lar. Specimens,.
D12U3-67 (1974) LOSS of Plasticizer from ?las:ic"> i«ctivacea Caroon Mecnods],
01204-78 Linear Dimensional Cnanges of Nonrigid Tnermopl ast i c Sneeting or Film at elevated Temperature.
01239-55 Resistance of Plastic Films to Extraction 3y Cnemical s : *st metnod discontinued -n I960;.
C1593-SO Nonrigia vinyl Chloride Plastic Sneeting, Specification -jr.
01693-70 (1980! Environmental St ress-Cracn i ng of Et.iyiene 'lastics.
3:79U-62 ;19.75' Brittleness Temoeratjre of Plasnc r' 1m Dy Imoact.
D2136-66 (19'S1 Coated Faorics - uo*- Tempera ture iiend Test.
02240-dl SuDDer Property - Ourometer Hardness.
33083-76 ,1980) Flexiole ?oly(Vinyl Cnlonde; 'lastic Sneeting fjr Sons , Sana!, ana -^ese^voir _ining. Spec-
ification for. Section 9.5 Soil Burial; Section 9.6 water Extraction; Section 9.4 "innoies
and Cracks.
dAs listed in tne 1981 and 1982 issues of tne ASTM standards. Numoer in parent.neses indicates tne year of
last reapproval oy tne committee witn jurisdiction for tne standard.
408
-------
•ABU /i::-3. sui
Properties
Analytical properties
Speci fie qravi ty
•cal properties
Tnicuness. i tolerance
Minimum tensile orooert'.es ',eacn
di rection; :
(1) dreaxing factor, ypi «idtn
(2) Elonyation it oreax , i
(3) Stress Jt 100% elonqation.
ppi *idtn
Tear strenqtn. IB ;min;
Hardness Ouro A, pts
Strengtn of factory seams (tested
jGESTcD 5*
ASTM
test
•netnod4
3297-A
31593
0412
3624
32240
33083/
ANOAROS -3R R-Xiai- «E."SRA,NE .INE^S «i*HOOT r-dSIC •t£:NFCRC-*E<:3
in snear). opi «i dtn -ni n)
tnvircnmental Jnd
effects an
reetioni. jerceit
Resistance to soil Dur'ji 'or
12'J Jays -na«inum jerceit
cnjnqe from jri^inal ^alue
i 1) dreax mq rector
;2' J'onqation it 3reax
i,3) stress it 1JO, tflonqation
;4) modulus of elasticity
-eit jqnq
-jncji : ',an<,
'. jred«iiq "Jctjr,
c; £1 onqat ion , *. m n i
,3) ^ardness cianqe. 3uro A
jonts. ^iaij
Jzone Assistance jt 40JC
Jtner conditions
Water aosorption, s [«H*)
<<4ter extraction. \ (max)
SO jpnm
-i
3471
33083
2QX extension
130 T
to crjcxsj
2
2'?l ^xteis ion
" }
NO :,-3cxsJ
J' ^»:e"s -o
" :
to : r i c x s -^
'.3
c,
JFor more dttails reyiralng conditions and titles of test necnoas, see 'aoles VIJ.'-l and Ull-l.
BEptcnloronyann ruBB«rs. ECO • copol/mer; CO • Homopol/mer.
C0ata unavailaol* at tnis tin*.
dNo cracits visiale under 7x magnification.
409
-------
viIJ-4. SUGGESTED STANOA«OS FOH FLEXIBLE MEMB«ANE UNERS
Volatile loss. * (max)
Mecnanical properties
Tnickness,
(1) Nominal , mi 1 s
(2) Actual, mi Is (mm)
Minimum tensile properties in eacn
direction
(1) Breaking factor, ppi *idtn
(2) Elongation at break, 1
(3) Stress at 100* elongation,
ppi widtn
Tear strength. 11> (mm)
Strenytn at factory seams,
(tested in snear; ppi wiatn (mini
Hyarostatic resistance, psi (mm)
Environmental and aging effects on
properties
Dimensional stability, *. cnange
;max)
LOW temperature
;bri:tieness temperature1, °f
tmax,
Resistance to soil Durial far
120 days 'vmaximum percent
cnange from original value)
(1) Breaking factor
(2) Elongation at break
(3) Stress at 100S elongation
Ozone resistance at 408C
J100U
0751-A
01204
75
4.5
i0°
5.
12.0
32. d
100
03083
Is
-20
-5
-20
+20
(c)
-5
-20
Water extraction, i (max)
«.-- -u.J5 -0.35
aFor more details regarding conditions and titles of test metnods, see "ables
6Poly(vmyl cnlonde) -oil resistan
unavailable at tnis time!
410
-------
Su'UGcST-O STANDARDS .-OR FLtXIBU -£."8RANE L.'N
Partial ly Crystal 1 me
properties
Analytical properties
Specific gravity
Volati le loss, ', -nax
Mecnanical properties
Tnicuness, nils (range)
Tensile properties, minimum
in eacn di rection
(1) Tensile at yield, poi «iatn
i 2) £1 ongation at yiel d, :
(3) dreading factor, api «idtn
(4) Elongation at arean , :
(5) Stress at 1001 elongation.
ppi «idtn
modulus of elasticity.
PSi (mm)
"ear strength, ID (nti)
jnore 0 njraness, jts
donoeo seam st"»i'jt'1, 'ictory
i^^i-^nrn^ntli JrJ i j ' " t •?' '*'.'* : n
jr)cer-"?S
ASTM
test
,netnod°
3792-A 0.
31203-A
01593
0638
0638
01004
32240
"emoranes
ELPO*
20 mil
92+0.05
0.5
17-24
(c)
(c!
34
500
12. d
(c)
5.1
.-;
1 ' ?
r ;A8RIC •!£;
HOPE
30 .111
0.930
mm
(c)
72-30
120
10
120
500
(c)
30.000
40
;o
NFORCE.1E.NT
HDPE-A1 lay
1 40 nil 1
X930
mi n
0.1
36-40
50
20
140
600
(c)
45,000
20
"-
tanperature; , JF -nax ;
•(eststjnc* :o soi : :ur;ji 'o
120 Jays -maximum percent
-Hange 'r^m jri^inal /aue
3746
-40
-40
. "ins ; ] e jt /' ei J
£ : jnijjc 'on )t i ' ei J
"ens; e it tjrea*
•> -,\ :nija* ' 3n jc ore j«
5; Stress Jt IJU^ elongation
,6) iQdulus of' elasticity
Ai - oven igl ng ^ ,
j5 / J
, 1) ireaxmg 'actor,
3pi , xidtn , ,-ni n 1
,2) Elongation, : j.nm)
Jzone resistance at 40"C 31149/0513
Environmental stress cracumg, *
". (mm) 01693
Water extraction, : ,max) 01239
~
-
f ^
IJ
10
(c)
33
425
,NO
cracxs
(c)
-0.35
LO
;.j
10
.0
c ;
;o
- j
'O
|C)
500
(c)
10
;j
.0
10
c,
10
; j j
:o
No
cracxs'
500
(c)
*Elast1c1zed polyolefm.
°fror more details regarding conditions and titles of test metnods, see Taoles VIII-1
and VIIi-2.
'Data unavailable at tnis time.
dHaximum percent cnange In eacn direction In 15 m1n at lOp'C.
*14 days at 70*C.
fNo cracks visiole at 7x magnification.
411
-------
TABLE VIII-6. SUGGESTED STANDARDS FOR FA8RIC-SEINFOKCEO FLEXIBLE 1EM8RANE LINERS
Tnermoplastic Coatings of CPE. Nltnlt Suoeer - PVC, E.DPW, ana EIA
ASTH
Properties test metftod*
Analytical properties
Volatile loss, 1 (»4x) 01203 0.5
Mecnanical properties
Tnicuness 0751
(1) nominal, mils Optically 36
(2) Minimum, mi Is 32
(3) Coating over faoric, mils (mfn) 11
Minimum tensile properties
leacn direction) 0751-A (gran)
ID oreamng strengtn. ID 120
; 2: Breaking factor of sneet mtn-
out faoric reinforcement, ID (c)
;3) elongation at Drean of sneet
witnout faoric reinforcement.
ID (c)
;4) Stress at lOOt elongation of
sneet xitnout faonc rgmforce-
ment , c '
Tear resistance, lo mm1 D'Si-d 25
ivdrostattc res'stance. osi .mm 0'5i-A-Droc 1 150
•'it adnesior eacn direction..
ID in <*l:3t" m?n ,^41j-- 1^
jt^eiijtn G* factorv Seam, i o inn v'i.-'VJC"' yo
• nv i ""onmentd i and duiiy effects
or properties
jimensionai scaotlity leacn direc-
tion , : change ,max; 01204 2
LU» temperature lanttieness
temperature . "F imai 02136 -40
A" o»en dgmg 'or 3U J at iOO'C D5"3
'fir resistance after aging, "51-3
i 0 . fin n 20
«(?s ; stance ts so i Durial 'or
. 1 greamng strengtn of 'aonc -25
2 sreamng 'ac:or of sneet mtn.
out faoric reinforcement -5
j I'onydtion jt ored« 3* sneet
•itnout faoric reinforcement -20
4 Stress at UUi eiongatton of
sneet witnout 'aoric rein-
forcement »10
jione resistance at 40"C 01149 (c)
(Dent loop at 100 ppnm Oj 0518
for ; Jays)
nater extraction, I (max) 03U83 (c)
xater aosorption, i gain (max) 0471
14 days «t 21*C c)
14 days at 70*C ie)
CPE N1tr1le
al loy ruDtxr
CPE (CPE-A) PVC
0.5 0.5 0.7 1.0
36 45 36 30
34 41 34 27
11 11 11 11
200 200 200 50°
(c) (c) (c) (c)
(c! .: 9C
-25 -25
- 1 j -10
-20 -20
-30 -15
no no
cracxs8 cracnse
(e) 0.35
(c) 1
(c) 2
*For more aetails regarding conditions and titles of test metnod, see Taoles VIII-1 and VII1-2.
"Faaric Drea». Coating is stronger tnan tne faoric and nas a Sreaking strengtn of 80 ID and 1201 minimum elongation
Drean.
C0ata unavailaole at tnis time.
aMeasured at 12 incnes per minute, specimen 4" »ioe and mtn 4 1/2" on eitner side of seam.
*No vtsiDle cracxs at 7x magnification.
412
-------
:Adi£ /;;;-/.
j STANCAMOS -~os --3s;c-*Ei?; -•< '
'. ion i , ; cnanqe
:«;:-*
JU'U4
Ai- Oven jgi"q 'or 3J 3j
it IJO'C
(e)
(e)
10
iQ
-40
120
(e)
(e)
25
:6U
-•JU
20
2UO
(e)
(e)
(e)
60
250
-40
25
125
(e)
(a)
30
j
-40
25
200
(e)
(e)
e)
'0
.'50
25
:j.s "J >'"urn -e
•jctor or ),"eec «i:nout
'ior-c rei
3 ; ongation It or»a« or sneet
4' 5fess it :jCi elongation or sneet
• ivout 'Jor'c renforsemene
•ater e«traction, ; nax,
«ater apsorotion, •.
14 days it 2\\
14 aays at 70"C
jam naxj
j47l
1.5"
303
-20
•10
e)
•30 -10
.
30^
.
30"
-20
-30
'io0
^Values appl/ to ootn graaes, except for tnose specifically noted for maustnal grades only. Tne
different types of nemoranes are classified oy tne type of faoric tnat 15 jsed to reinforce :ne nem-
orane. A Type-A nemora/ie is typically reinforced «itn a 6 x 6 ends per men (epi) faonc; a Type-3
memorane is typically reinforced «itn an i i A api; and a Type-C nemorane is typically reinforced »itn
a 10 x 10 epi faoric. Polyester faoric is jsed for reinforcement.
°for more details regarding conditions and titles of test netnod, see "aoles '/lll-l and VIII-2.
cCoacmg 15 stronger tnan tne faonc and nas a oreanmg strengtn of 100 IB for 30 mils and 1501 min-
ima elongation at orean.
d*pply to industrial grades of CSPE membranes only. — • -
•No data availaole at tms time.
^Measured at 12 tncnes per minute, specimen 4 1/2" on eacn side of seam and 4" «,de.
413
-------
GLOSSARY OF TERMS RELATING TO LINER TECHNOLOGY
The intent of this glossary is to define the terms used in this Technical
Resource Document. A glossary is considered desirable because of the diverse
origins of the liner technology and the broad spectrum of potential users of
this document. If possible, generally accepted definitions were selected.
The sources of each are indicated with the definition. However, if an ap-
propriate definition could not be found, one was prepared. The definitions
are presented by area of expertise, thus some definitions may appear more than
once. The areas of expertise are:
1. Admix liner materials
2. Asphalt technology
3-. Chemistry
4. Hazardous waste management
5. hydrology
6. Polymeric membrane liners
7. Site construction
8. Soil science and engineering
9. Solid waste management
After the review period, we propose to comoine tne final revised list of
terms into a single list and to eliminate the references to the sources
of the definitions which are presented in the attached list.
414
-------
GLOSSARY
ADMIX LINES MATERIALS
ADMIX - Two or more materials mixed together at or near the waste disposa
facililty to be lined. These materials i :lude asphalt concrete, portlant
cement concrete, and mixtures of soil and asphalt or portland cement.
ADMIXTURES - Substances that are added to mortar, stucco, cement plaster, anc
concrete to produce specific results. They may or may not cause a chemical
reaction within the above substances, but usualy a chemical reaction does
occur. Asphalts may be added for waterproofing compounds (Hornbostel, 1978).
BENTONITE - See Soil Science and Engineering.
COMPACTION - A process of densifying soil cement, soil asphalt, and aschalt
concrete by the use of sneepsfoot rollers, ruober-tired rollers, and smooth
steel rollers.
HYDRAULIC ASPHALT CONCRETE - See Asphalt Technology Glossary.
SOIL ASPHALT - A compacted mixture of soil and asphalt cement. Cutback or
emulsified asphalts are usually avoided.
SOIL CEMENT - A mixture of soil, Portland ceme'1:, and water. As the cement
hydrates, the mixture foms a nard, durable, ] :w strength concrete (Day,
1970).
415
-------
GLOSSARY
ASPHALT TECHNOLOGY
AGGREGATE - A granular material of mineral composition such as sand, gravel,
shell, slag, or crushed stone, used with a cementing medium to form mortars or
concrete, or alone as in roadway base courses, railroad ballast, etc. (ASTM
08).
ASPHALT - A dark brown to black semisolid cementitious material consisting
principally of bitumens which gradually liquefy when heated and which occur
in nature as such or are obtained as residue in the refining of petroleum
(Woods, 1960).
ASPHALT CEMENT - A fluxed or unfUixed asonalt specially prepared as to Quality
and consistency for direct use in the manufacture of oituminous pavements and
having a oenetration at 25°C (77°F) of between 5 and 300, under a load of lOOg
applied for five seconds (ASTM, 03;.
ASPHALT MEMBRANE - A relatively tmn layer of asphalt formed by spraying
a nigh viscosity, nigh softening point asphalt cement in two or more applica-
tions over tne surface to be covered. It is normally 1/4" thick and buried
to protect it from weathering and mechanical damage.
ASPHALT PANEL - A laminate consisting of a core c* blended asphalt, mineral
fillers, and reinforcing ficers sandwiched between protective sheets and
a protective coating of not-applied aspnalt.
ASPHALT RUBBER - Aspnalt containing a minor amount of ground vulcanized
rubbers which can be sprayed on prepared surfaces to form a membrane.
BATTEN - In asphalt technology, a strip usually made of asphalt used to
seal the joints oetween asphalt panels.
BITUMEN - A class of black or dark colored (solid, semisolid, or viscous)
cementitious substances, natural or manufactured, composed pricipally of
relatively high molecular weight hydrocarbons. Asphalts, tars, pitches,
and asphaltites are typical examples of bitumen (ASTM, 08).
BLOWN ASPHALT (AIR-BLOWN ASPHALT) - Asphalt produced in part by blowing air
through it at a high temperature. If a catalyst, e.g. ferric chloride or
phosphorus pentoxicle, is used in the air blowing operation, the product is
known as catalytically-blown asphalt (Woods, 19.60.)..
COAL TAR - Tar produced by the destructive distillation of bituminous coal
(ASTM, D8).
416
-------
COURSE - See "Lift".
CUTBACK ASPHALT - Asphalt cement that has oeen liquefied by blending wit
petroleum solvents which are also, in this context, called diluents. Upo
exposure to atmospheric conditions the diluents evaoorate leaving the asphal
cement to perform its function (Asphalt Institute, MS-5).
EMULSIFIED ASPHALT - A mixture of asphalt and water in which the asphal
is held in suspension in the water by an emulsifying agent. Emulsifie<
'asphalts may be either cationic or aniomc depending on the emulsifying agem
used.
HYDRAULIC ASPHALT CONCRETE - Similar to asphalt concrete designed for roadwa}
paving, except that it has a higner mineral filler and asphalt content ir
order to insure an essentially voidless mix after compaction (Asphalt Insti-
tute, MS-12).
LIFT - An applied and/or compacted layer of soil, asphalt, or waste. In
a sanitary landfill, a 1ift is a compacted layer of solid wastes and a top
layer of cover material. Also referred to as a course (EPA, 1972).
MASTIC - A mixture of mineral aggregate, mineral filler, and asohalt in
such prooortions tnat tne mi< can oe acolied no: oy souring or by mechanical
manipulation; it forms i /O':'es3 iass ^itnout oeing compacted (Asphalt
Institute, MS-12).
MINERAL FILLER - A finely divided mineral oroduct of ^hich at least 65% will
pass a No. 200 sieve wmch has a sieve opening of 74 ym. Pulverized lime-
stone is the most common manufactured fil'^, although other stone dust,
silica, hydrated lime, port'and cement, ar.j :ertain natural deposits of
finely divided matter are also used (Aspnalt Institute', MS-5).
MIX - The amounts of aggregates arc: assna'. t *p' :n are combined to give the
desirea properties in tne finisnec procjct?
PENETRATION - The consistency of a bituminous material expressed as the
distance in tenths of a millimeter (0.1 nm) that 3 standard needle penetrates
vertically into a sample of the material under specified conditions of load-
ing, time, and temperature determined Dy ASTM OS '-STM, D8),
PENETRATION GRADE - Classification of asphalt cement into ranges of penetra-
tion values specified in ASTM D946.
SOFTENING POINT - Temperature at which a bitumen softens in the ring-and
ball method described in ASTM 023-98. Used in the classification of bitumen,
particularly of bitumen intending for roofing, because it is indicative of
the tendency of a material to flow at elevated temperatures encountered
in service.
VISCOSITY GRADE - Viscosity classification for asphalt cement into ranges
specified in ASTM D3381.
417
-------
GLOSSARY
CHEMISTRY
ABSORPTION - Ability of a porous solid material to hold within its body
relatively large quantities of gases or liquids (Bennett, 1947).
ACIDITY - Quantitative capacity of aqueous solutions to react with hydroxyl
ions. It is measured by titration with a standard solution of a base to
a specified end point. Usually expressed as milligrams of calcium carbonate
per litre (EPA, 1977).
ADSORPTION - The adhesion of an extremely thin layer of molecules (of gases
or liquids) to the surface of solids or liquids with which they are in contact
(EPA, 1977).
ALKALINITY - The capacity of water to neutralize acids, a property imparted by
the water's content of carbonates, bicarbonates, hydroxides, and occasionally
borates, silicates, and phosphates. It is expressed in milligrams of calcium
carbonate equivalent per litre (EPA, 1977).
ANALYSIS - The determination of the nature or oroportion of one or more
constituents of a substance, whether separated out or not (Webster's New
World Dictionary).
ASH (FIXED SOLIDS) - The incombustible material :nat remains after a fuel
or solid waste has been burned.
ATTENUATION - Any decrease in the maximum concentration or total quantity
of an applied chemical or biological constituent in a fixed time or distance
travelled resulting from physical, chemical, ana/or biological reaction
or transformation (Fed. Regist., 1978).
8005 (Five Day Biochemical Oxygen Demand) - A measure of the relative oxy-
gen requirements of waste-waters, effluents and polluted waters. BOD values
cannot be compared unless the results have been obtained under identical test
conditions. The test is of limited value in measunng the actual oxygen
demand of surface waters (APHA - AWWA - WPCF, 1975).
COD (Chemical Oxygen Demand) - A measure of the oxygen equivalent of that
portion of the organic matter in a sample that ^s susceptible to oxidation
by a strong chemica'l oxidant (APHA - AWWA - WPCF, i975).
CONTAMINATION - A substance or substances that renders a body of water, soil,
sample, etc. impure, unclean or corrupt by contact (Webster's New World
Dictionary).
1 418
-------
DIFFUSION - The material permeation of two or more substances due to
kinetic activity of their molecules, so that a uniform mixture or solut
results. Diffusion occurs with all forms of matter; it is most rapid
gases, somewhat slower for liquids and for solids in solution.
EXTRACTABLES - Components or substances removable from a solid or liqi
mixture by means of an appropriate solvent (Hampel and Hawley, 1976).
HYDROCARBONS - An organic chemical compound containing mainly the elemer
carbon and hydrogen. Aliphatic hydrocarbons are straight chain compoun
of carbon and hydrogen. Aromatic hydrocabons are carbon-hydrogen compoun
based on the cyclic or benzene ring. They may be gaseous (Cfy, ethyl en
butadiene), liquid (hexene, benzene), or solid (natural rubber, napthalen
cis-polybutadiene) (Goodrich, 1979).
HYDROGEN SULFIDE - (H^S) - A poisonous gas with the odor of rotten eg<
that is produced from the reduction of sulfates and the putrefaction c
sulfur containing organic matter (EPA, 1977).
ORGANIC CONTENT - Usually synonymous with volatile solids in an ashing test
a discrepancy between volatile solids and organic content can be cause
by small traces of some inorganic materials such as calcium carbonate tha
lose weight at temperatures used in determining volatile solids (EPA, 1972)
OSMOSIS - The diffusion which proceeds through a semipermeable membran
typically separating two solutions, or a solvent and a solution, and tendin
to equalize their concentrations. The net movement in osmosis is diffusioi
of solvent into the more concentrated solution (Webster's New Collegiate
Dictionary).
pH - (1) The negative log of the hydrogen ion concentration, a measure of
acidity and alkalinity (EPA, 1972). (2) A measure of the relative acidity
or alkalinity of *ater. A pH of 7.0 indicates a neutral condition. A greater
pH indicates ai
-------
GLOSSARY
HAZARDOUS WASTE MANAGEMENT
ACIDIC WASTE - A waste that has a low pH.
AERATION SYSTEM - A system which exposes a bulk material, such as a compost,
to air, or which charges a liquid with a gas or a mixture of gases (EPA
1972).
BIODEGRADABLE - Susceptible to decomposition as a result of attack by micro-
organisms - said of organic materials (Hempel and Hawley, 1976).
CHEMICAL FIXATION - Treatment process which involves reactions between the
waste and certain chemicals, and which results in solids which encapsulate,
immobilize or otherwise tie UD hazardous components in the waste so as to
minimize the leaching of hazardous components and render the waste non-
hazardous or more suitaole for disposal.
COLLECTION (DRAINAGE) SYSTEM - Structures and facilities for collecting
and carrying away water or other liquids (Asphalt Institute, MS-15).
COMPATIBILITY - Ca c -ility of existing together without adverse effects.
Applied primarily to comm nations of waste fluids and liner materials.
FACILITY - Any land and appurtenances thereon and thereto, used for treatment,
storage and/or disposal of hazardous; waste (Fed. Reg'st., 1973).
FLY ASH - All solids, including ash, charred paper, cinders, dust, soot,
or other partially incinerated matter that are earned in a gas stream (EPA,
1972).
HAZARDOUS WASTE - A solid waste or combination of solid wastes, which because
of its quantity, concentration or physical, :nenical, or infectious character-
istics may:
a. cause, or significantly contribute to an increase in mortality or
an increase in serious irreversible, or incapacitating reversible,
illness; or
b. pose a substantial present or potential hazard to human health or the
environment .vnen improperly treated, stored, transported, or disposed
of, or otherwise managed (Public Law 94-580, 1976).
HEAVY METALS - A general name given to the ions of metallic elements such
as copper, zinc, chromium, or aluminum. They are normally removed from a
wastewater by forming an insoluble precipitate, usually a metallic hydroxide
(EPA, 1977).
420
-------
HERBICIDE - A type of pesticide, including so called weed-killers, silvicidf
and defoliants, which kills or otherwise eliminates shrubs, small tres
grasses, etc. There are both organic and inorganic herbicides: the latt
is typified by common salt, sodium borate, and various arsenical comoounc
the former by 2, 4-0 and similar chlorinated compounds and by the defolia
picloram (EPA, 1977).
IMPOUNDMENT - See "Surface Impoundment" in Site Construction Glossary.
INDUSTRIAL WASTE - The liquid wastes from industrial processes as distin
from domestic or sanitary waste (EPA, 1977).
LEACHATE - See Solid Waste Management Glossary.
LINER - See Solid Waste Management Glossary.
MONITORING - All systematic procedures used to inspect and collect dat
on operational parameters of a facility or on the quality of the air, ground
water, surface water or soil.
MONITORING WELL - A well used to obtain water samples for *ater qua! it
analysis or to measure 'jroundwater levels.
PESTICIDE - See Solid Waste Manage|rient Glossary.
SOLID WASTE - See Solid Waste Management Glossary.
SUMP - A pit or well in which liquids collect (Webster's New World Diction-
ary).
TOXICANT - A toxic agent, especially one fo - insect control,_ that kills
rather than repels (Webster's Collegiate Di ctic"3<*y).
TOXIN - (1) Any of various unstaole poisonous ccmoounds produced by some
microorganisms and which cause certain diseases. (2) Any of various similar
poisons, related to proteins, secreted by plants and animals (Webster's
New World Dictionary).
421
-------
GLOSSARY
HYDROLOGY
AQUIFER - A geologic formation, group of formations, or part of a formation
that is capable of yielding usable quantities of groundwater to wells or
springs (Fed. Regist. , 1978).
CAPILLARY WATER - Underground water that is held above the water table by
capillary action (EPA, 1972).
DISSOLVED SOLIDS - Solids or particles small enough to be part of a solution.
Dissolved solids will pass through a glass fiber filter (APHA - AWWA - WPCF
1975).
FLUX - (1) A bituminous material (generally liquid) used for softening other
bituminous materials. (2) The rate of flow of a solute through a porous
medium; or more technically, the volume of flow per unit time per unit area
perpendicular to tne direction of How referred to as the Darcian velocity of
flux density (Fuller, 1973).
GROUNDWATER, FREE - (1) Groundwater in aauifers. ! 2} Water in the saturated
zone beneath the land surface (Fed. Regist., 1978).
HEAD, (PRESSURE) - Pressure measurec as an equivalent height of water.
HYDRAULIC GRADIENT - The change in hydraulic oressure per unit of distance in
a given di rection.
HYDROLOGY - Science dealing with tne properties, distribution, and flow of
water on or in the earth (EPA, 1972).
RUN OFF - That portion of precipitation or irrigation water that drains from
an area as surface flow (EPA, 1972).
SLOPE - Deviation of a surface from the horizontal expressed as a percentage,
by a ratio, or in degrees (EPA, 1972).
WATER TABLE - (1) The upper limit of the part of the soil or underlying
rock material that is wholly saturated with water (EPA, 1972). (2) The upper
surface of the zone of saturation in groundwaters in which the hydrostatic
pressure is equal to atmospheric pressure (Fed. Regist., 1978).
WATER TABLE, PERCHED - A water table, usually of limited area, maintained
above the normal free-water elevation by the presence of an intervening,
relatively impervious stratum (EPA, 1S72).
422
-------
ZONE OF AERATION - Area above a water table where the interstices (pores)
are not completely filled with water (EPA, 1972).
ZONE OF CAPILLARITY - The area above a water table where some or all of
the interstices (pores) are filled with water that is held by capillary
action (EPA, 1972).
423
-------
GLOSSARY
POLYMERIC MEMBRANE LINER TECHNOLOGY
ADHESION - The state in which two surfaces are held together by interfacial
forces which may consist of molecular forces or interlocking action or both.
Measured in shear and peel modes. (Goodrich, 1979).
AIR LANCE - A device used to test, in the field, the integrity of field seams
in plastic sheeting. It consists o-r a wand or tube through which compressed
air is b1 own.
ALLOYS, POLYMERIC - A blend of two or more polymers, e.g. a rubber and a
plastic, to improve a given property, e.g. impact strength.
ANCHOR TRENCH - A long narrow ditch on which the edges of a pi astic-sheet are
buried to hold it in place or to anchor the sheet.
BERM - The upper edge of a pit or pond where a membrane liner is anchored.
The berm may be wide and solid enough for vehicular traffic.
BLOCKING - Unintentional adhesion usually occurring during storage or shipping
between plastic films or between & film and another surface (ASTM D883).
BODIED SOLVENT ADHESIVE - An adhesive consisting of a solution of the liner
compound used in the seaming of liner membranes.
BOOT - A bellows type covering to exclude dust, dirt, moisture, etc., from a
flexible joint (Goodrich, 1979).
BREAKING FACTOR - Tensile at break in force per unit of width; units, SI:
Newton per meter, customary: pound per inch.
BUTYL RUBBER - A synthetic rubber based on isobutylene and a minor amount of
isoprene. It is vulcanizable and features low permeability to gases and water
vapor and good resistance to aging, chemicals, and weathering.
CALENDER - A precision machine equipped with three or more heavy internally
heated or cooled rolls, revolving in opposite directions. Used for prepara-
tion of highly accurate continuous sheeting or plying up of rubber compounds
and frictioning or coating of fabric with rubbe-r or plastic compounds (Good-
rich, 1979).
CHLORINATED POLYETHYLENE (CPE) - Family of polymers produced by chemical
reaction of chlori.ne on the linear backbone chain of polyethylene. The
424
-------
resultant rubbery thermoplastic elastomers presently contain 25-45% chlorine
by weight and 0-25% crystallinity. CPE can be vulcanized but is usually used
in a nonvulcanized form.
CHLOROSULFONATED POLYETHYLENE (CSPE) - Family of polymers that are produced by
polyethylene reacting with chlorine and sulfur dioxide. Present polymers
contain 25-43% chlorine and 1.0-1.4% sulfur. They are used in both vulcanized
and nonvulcanized forms. Most membranes based on CSPE are nonvulcanized (ASTM
designation for this polymer is CSM).
COATED FABRIC - Fabrics which have been impregnated and/or coated with a
rubbery or plastic material in the form of a solution, dispersion, hotmelt, or
powder. The term also applies to materials resulting from the application of
a preformed film to a fabric by means of calendering.
CREEP - The slow change in length or thickness of a -material under prolonged
stress.
CROSSLINKING - A general term referring to the formation of chemical bonds
between polymeric chains to yield an insoluble, three dimensional polymeric
structure. Crosslinking of rubbers is vulcanization (q.v.).
CURING - See "Vulcanization".
DENIER - A unit used in the textile industry to indicate the fineness of
continuous filaments. Fineness in deniers equals the mass in grams of 9000
meter length of the filament.
DIELECTRIC SEAMING - See "Heat Seaming".
ELASTICITY - The property of matter by virtue of which it tends to return to
its original size and shap~e after removal of the stress which caused the
deformation (Go'odrich, 1979).
ELASTOMER - See ."Rubber".
EPDM - A synthetic elastomer based on ethylene, propylene and a small amount
of a non-conjugated diene to provide sites for vulcanization. EPDM features
excellent heat, ozone and weathering resistance and low temperature flexi-
bility.
EPICHLOROHYDRIN RUBBER - This synthetic rubber includes two epichlorohydrin-
based elastomers which are saturated, high molecular weight, aliphatic
polyethers with chloro-methyl side chains. The two types include a homo-
polymer (CO) and a copolymer of epichlorohydrin and ethylene oxide (ECO)
These rubbers are vulcanized with a variety of reagents that react difunc-
tionally with the cnloromethyl group; including diamines, urea, thioureas,
2-mercaptoimidazoline, and ammonium salts.
EXTRUDER - A machine with a driven screw for continuous forming of rubber by
forcing through a die; can be used to manufacture films and sheeting.
EVA - Family of copolymers of ethylene and vinyl acetate used for adhesives
and thermoplastic modifiers. They possess a wide range of melt indexes.
425
-------
FABRIC-REINFORCEMENT - A fabric, scrim, etc., used to add structural strength
to a 2 or more ply polymeric sheet. Such sheeting is referred to as
"supported".
FILL - As used in textile technology refers to the threads or yarns in a
fabric running at right angles to the warp. Also called filler threads.
(Rubber Manufacturers Assn., 1969).
FILM - Sheeting having nominal thickness not greater than 10 mils (ASTM,
D883).
HEAT SEAMING - The process of joining two or .nore thermoplastic films of
sheets by heating areas in contact with each other to the temperature at which
fusion occurs. The process is usually aided by a controlled pressure. In
dielectric seaming the heat is induced within films by means of radio fre-
quency waves.
LAPPED JOINT - A joint made by placing one surface to be joined partly
over another surface and bonding the overlapping portions (Whittington,
1968).
LENO FABRIC - An open fabric in which two warp yarns wrap around each fill
yarn in order to prevent the warp or fill yarns from sliding over each
other.
MEMBRANE - In this Manual the term membrane applies to a continuous sheet of
material whether it is prefabricated as a flexible polymeric sheeting or is
sprayed or coated in the field, such as a sprayed-on asphalt.
MODULUS - The stress on stretching a material to different elongations,
e.g. s-100% and s-200%.
MODULUS OF ELASTICITY - The ratio of stress to strain within the elastic
range, also known as Young's modulus (ASTM, 1972).
NEOPRENE (POLYCHLOROPRENE) - Generic name for a synthetic rubber based primar-
ily on chloroprene, i.e. chlorobutadiene. Vulcanized generally with metal
oxide. Resistant to ozone and aging and to sone oils.
NITRILE RUBBER - A family of copolymers of butadiene and acryl onitrile that
can be vulcanized into tough oil resistant compounds. Blends with PVC are
used where ozone and weathering are important requirements in addition to its
inherent oil and fuel resistance.
NYLON - Generic name for a family of polyamide polymers characterized by the
presence of the amide group -CONH^. Used as a scrim in fabric reinforced
sheeting (Cond. Chem. Diet., 1977).
PERMEABILITY - (1) The capacity of a porous medium to conduct or transmit
fluids (ASCE.1976). (2) The amount of liquid moving through a barrier in a
unit time, unit area, and unit pressure gradient not normalized for but
directly rel ated. to thickness (Wren, 1^73).
426
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PLASTIC - A material that contains as an essential ingredient one or more
organic polymeric substances of large molecular weight, is solid in its
finished state and at some stage in its manufacture or processing into
finished articles, can be shaped by flow (ASTM D883).
PLASTICIZER - A plasticizer is a material, frequently "solvent-like", incor-
porated in a plastic or a rubber to increase its ease of workability, its
flexibility, or distensiblity. Adding the plasticizer may lower the melt
viscosity, the temperature of the second order transition, or the elastic
modulus of the polymer.
Plasticizers may be monomeric liquids (phthalate esters), low molecular weight
liquid polymers (polyesters) or rubbery high polymers (EVA).
The most important use of plasticizers is with PVC where the choice of plasti-
cizer will dictate under what conditions the liner may be used.
POLYESTER FIBER - Generic name for a manufactured fiber in which the fiber-
forming substance is any long chain synthetic polymer composed of an ester of
a dihydric alcohol and terephthalic acid. Scrims made of polyester fiber are
used for fabric reinforcement.
POLYMER - A macromolecular material formed by the chemical combination of
monomers having either the same or different chemical composition. Plastics,
rubbers, and textile fibers are all high molecular weight polymers.
POLYMERIC LINER - Plastic or rubber sheeting used to line disposal Sites,
pits, ponds, lagoons, canals, etc.
POLYVINYL CHLORIDE (PVC) - A synthetic thermoplastic polymer prepared from
vinyl chl oride. PVC can be compounded into flexible and rigid forms through
the use of plasticizers, stabilizers, fillers, and other modifiers; rigid
forms used in pipes and well screens; flexible forms used in manufacture of
sheeting.
PUNCTURE RESISTANCE - Extent to which a material is able to withstand the
action of a sharp object without perforation. Examples of test of this
property are Federal Test Method Standard No. 1018, Methods 2031 or 2065.
ROLL GOODS - A general term applied to rubber and plastic sheeting whether
fabric reinforced or not. It is usually furnished in rolls.
RUBBER - A polymeric material which, at room temperature, is capable of
recovering substantially in shape and size after removal of a deforming
force. Refers to both synthetic and natural rubber. Also called an elastomer.
SCRIM - A woven, open mesh reinforcing fabric made from continuous filament
yarn. Used in the reinforcement of polymeric sheeting (Whittington, 1968).
SEAM STRENGTH - Strength of a seam of 1iner material measured either in shear
or peel modes. Strength of the seams is reported either in absolute units,
e.g. pounds per inch of width, or as a percent of the strength of the sheeting.
427
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SHEETING - A form of plastic or rubber in which the thickness is very small in
proportion to length and width and in which the polymer compound is present as
a continuous phase throughout, with or without fabric.
STRIKETHROUGH - A term used in the manufacture of fabric-reinforced polymeric
sheeting to indicate that two layers of polymer have made bonding contact
through the scrim.
SUPPORTED SHEETING - See "Fabric-Reinforcement".
SURFACE CURE - Curing or vulcanization which occurs in a thin layer on
the surface of a manufactured polymeric sheet or other items.
TEAR STRENGTH - The maximum force required to tsar a specified specimen, the
force acting substantially parallel to the major axis of the test specimen.
Measured in both initiated and uninitiated modes. Obtained value is dependent
on specimen geometry, rate of extension, and type of fabric reinforcment.
Values are reported in stress, e.g. pounds, or stress per unit of thickness,
e.g. pounds per inch.
TENSILE STRENGTH - The maximum tensile stress per unit of original cross-
sectional area applied during stretching of a specimen to break; units:
Si-Mega on kilopascal, customary - pound per square inch.
THERMOPLASTIC - Capable of being repeatedly softened by increase of tempera-
ture and hardened by decrease in temperature. Most polymeric liners are
supplied in thermoplastic form because the thermoplastic form allows for
easier seaming both in the factory and on the field.
THERMOPLASTIC ELASTOMERS - New materials which are being developed, and which
are probably related to elasticized polyolefins. Polymers of tnis type benave
similarly to cross linked ruooer. Tney nave a limited upper temperature ser-
vice range wnich, however, is substantially above the temperature encountered
in waste disposal sites (200°F may be :oo high for some TPE's).
THREAD COUNT - The number of tnreads per inch in each direction with the warp
mentioned first and the fill second, e.g. a thread count of 20 x 10 means 20
tnreads per inch in the warp and 10 threads per inch in the fill direction.
ULTIMATE ELONGATION - The elongation of a stretched specimen at the time of
break. Usually reported as percent of the original length. Also called
elongation at break.
UNSUPPORTED SHEETING - A polymeric sheeting consisting of one or more plies
without a reinforcing fabric layer or scrim.
VACUUM BOX - A device used to assess the integrity of field seams in membrane
liners.
VULCANIZATE - Used to denote the product of the vulcanization of a rubber
compound without reference to shape or form.
428
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VULCANIZATION - An irreversible process during which a rubber compound,
through a change in its chemical structure, e.g. crosslinking, becomes less
plastic and more resistant to swelling by organic liquids, and during which
elastic properties are conferred, improved, or extended over a greater ranae
of temperature (ASTM, 1972). y
WARP - In textiles, the lengthwise yarns in a woven fabric (Rubber Manufac-
turers Assn., 1969).
WATER VAPOR TRANSMISSION (WVT) - Water vapor flow normal to two parallel
surfaces of a material, through a unit area, under the conditions of a
specified test such as ASTM E96.
429
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GLOSSARY
SITE CONSTRUCTION
ANCHOR TRENCH - See "Polymeric Membrane Liner Technology Glossary".
BLADE - A heavy broad metal plate attached to the front of a tractor.
U-"Universa1 " - A blade with extensions on each side that protrude
forward at an obtuse angle to the blade and enable
it to handle a larger volume than a regular blade.
Landfill: A U-blade with an extension on top that increases
the volume of solid wastes that can be pushed and
spread, and protects the operator from debris thrown
out of the sol id waste.
•
COURSE - See "Lift".
COVER', FINAL. - The cover material that is applied at the end of the useful
life of a disposal site and represents the permanently exposed final surface
of the fil 1.
COVER MATERIAL - A soil or other suitable material that is used to cover
the liner or wastes in a disposal site.
CUT AND COVER (CUT AND FILL) - An infrequently and incorrectly used term
referring to the trench method of sanitary landfilling (EPA, 1972).
CUT-OFF TRENCH - A trench that is filled with material that may be impermeable
or very permeable to the flow of gas or water. The barrier is used to prevent
the movement of gas or water or to intercept and to direct them to another
location (EPA, 1972).
DRAINAGE - Provision for directing the runoff that occurs from precipitation
or overland flow in such a way as to prevent contact with refuse or inter-
ference with landfill operations (ASCE, 1976).
EARTHEN DIKE - A dam constructed of soil and earth.
GEOTEXTILE - A textile fabric, such as a filter fabric used in civil engineer-
ing applications.
GRADE - (1) See "Gradient". (2) To level off to a smooth horizotal or sloping
surface. (3) A datum or reference level. (4) Particle sized distribution of
an aggregate.
430
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GRADIENT - The degree of slope or a rate of change of a parameter measured
over distance (EPA, 1972).
GROUT - A cementing or sealing mixture of cement and water to which sand,
sawdust or other fillers may be added (EPA, 1972).
IMPOUNDMENT - See "Surface Impoundment".
•LIFT - A single layer of compacted soil. Lift thickness depends on soil
and degree of compaction needed (also termed "course").
ROLLER - A heavy cylinder of metal, stone, etc., used to crush, compact,
or smooth a surface (Webster's New World Diet.).
SEEPAGE - Movement of water or gas through soil without forming definite
channels (EPA, 1972).
SETTLEMENT - A gradual subsidence of material (EPA, 1972).
SETTLEMENT DIFFERENTIAL - Non.-.iform subsidence of material from a fixed
horizontal reference plane (ASCE, 1976). More commonly known as "Differential
Settlement".
SHEEPSFOOT ROLLER - A tamping roller with numerous closely spaced "feet",
or solid cylinders, approximately 6 inches long and with a tamping area of
about 7 square inches'. It is often used in the compacting of soils. The
weight of the roller when loaded and used is required by the Bureau of Rec-
lamation to be not less than 4000 Ib. per foot of length of drain (Bur, Rec.,
1974).
SITE - Jobsite.
SLOPE - Deviation of a surface from the horizontal'expressed as a percentage,
by a ratio, or in degrees. In engineering, usually expressed as a ratio
of horizontal vertical change (EPA, 1972).
1 Slope = 6:1
SPRAY BAR - a long hollow tube with nozzles of any of a number of forms,
used to apply a thin layer or coat of a substance in liquid form. Spray bars
are attached by hoses and pneumatic lines to pumps to convey the liquid from
the storage truck or tank to the nozzles. - •
STABILIZATION - A stabilizing procedure, or to make stable, to firm, as
applied to a soil.
431
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SUBGRAPH - The foundation or suppporting soil layer for a liner. Subgrades
can be the surface of the upgraded native soil, but are more commonly special-
ly prepared, artificially compacted layers of soil.
SUBSIDENCE - Settling or sinking of the land surface due to many factors
such as the decomposition of organic material, consolidation, drainage, and
underground failure (EPA, 1972).
SUBSOIL - That part of the soil beneath the topsoil, usually not having
an appreciable organic matter content (EPA, 1972).
SURFACE COMPACTION - Increasing the dry density of surface soil by applying
a dynamic load (EPA, 1972).
SURFACE CRACKING - Discontinuities that develop in the cover material at
a sanitary landfill due to the surface drying of the cover or settlement of
the solid waste. Such discontinuities can permit entrance or egress of
vectors, intrusion of water, and venting of decomposition gases (EPA, 1972).
SURFACE IMPOUNDMENT - A natural topographic depression, artificial excavation,
or dike arrangement with the following characteristics: (1) it is used pri-
marily for holding, treatment, or disposal of waste; (2) it may be constructed
above, below, or partially in the ground or in navigable waters (e.g., wet-
lands); and (3) it may or may not have a permeable bottom and/or sides.
Examples include holding ponds and aerati-on ponds (Fed. Regist., 1978).
VENT - An opening to permit passage or escape of a gas or liquid (Webster's
New Worl d Dictionary ).
432
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GLOSSARY
SOIL SCIENCE AND ENGINEERING
AIR DRY - (1) The state of dryness (of a soil) at equilibrium with the mois-
ture, content in the surrounding atmosphere. The actual moisture content
will depend on the relative humidity and the temperature of the surrounding
atmosphere. (2) To allow to reach equilibrium in moisture content with
the surrounding atmosphere (SSSA, 1970).
AIR POROSITY - The proportion of the bulk volume of soil that is filled
with air at any given time or under a given condition such as a specified
moisture tension (SSA, 1970).
ALLUVIUM - A general term for all detrital material deposited or in transit
by streams, including gravel, sand, silt, clay and all variations and mixtures
of these. Unless otherwise noted, alluvium is unconsolidated (Brady, 1974).
AMPHOTERIC - Having the property of reacting with either an acid or a base*
Many oxides and salts have this ability (aluminum hydroxide, for example)
(Hampel and Hawley, 1976).
ANION EXCHANGE CAPACITY - The sum total of exchangeable anions that a soil
can absorb. Expressed as mi 11 iequi val ents per 100 gram of soil (or other
absorbing materials such as clay) (SSSA, 1970).
ATTERBERG LIMITS - Moisture content values which are measured.for soil mate-
rials passing a No. 40 sieve and which define soil plasticity properties.
Also referred to as plasticity limits. The Atterberg limits are as follows:
Shrinkage Limit (SL): The maximum water content at which a reduction
in water content will not cause a decrease in the volume of the
soil mass. This defines the arbitrary limit between the solid
and semi-solid states.
Plastic Limit (PL): The water content corresponding to an arbitrary
limit between the plastic and semi-solid states of consistency of
a soil.
Liquid Limit (LL): The water content corresponding to the arbitrary
limit between the liquid and plastic states of consistency of a
soil (Brady, 1974).
BEDROCK - The solid rock underlying soils" and the regolith at depths from
z-ero (where exposed by erosion) to several hundered feet (Brady, 1974).
433
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BENTONITE - A soft clay formed as a weathering product from volcanic ash
and composed chiefly of the mineral montmorillonite. Sodium bentonite is
notable for its ability to swell in water.
CATION EXCHANGE CAPACITY (CEC) - The sum total of exchangeable cations that a
soil can absorb; sometimes called "total exchange capacity", "base-exchange
capacity" or "cation absorption capacity". Expressed in milliequivalents per
100 grams of soil (or of other absorbing material such as clay).
CALIFORNIA BEARING RATIO (CBR) - The ratio of (1) the force per unit area
required to penetrate a soil mass with a 3 square in. circular piston (ap-
proximately 2 in. diameter) at the rate of 0.05 in./min. to (2) the force per
unit area required for corresponding penetration of a standard material.
Also known as the bearing ratio of laboratory compacted soils (ASTM D653,
D18833).
CLAY - Term is used in three ways: (1) Soil particles less than two micro-
meters in equivalent diameter. Cf. sand, silt (2) A secondary soil mineral
formed through weathering of primary minerals or transported. Mainly alumino-
silicates, some relevant characteristics are:
1. Large surface area.
2. Hydration/dehydration.
3. Cation exchange capacity.
4. Particles less than two micrometers.
5. Flocculation/dispersion.
(3) Soil material containing more than 40% clay, less than 45% sand and
less than 40% silt.
CLAY MINERAL - (1) Naturally occurring inorganic crystalline material found
in soils and other earthy deposits, the particles being of clay size, i.e.
<2 ym in diameter. (2) Material as described under (3) but not limited
by particle size (SSSA,, 1970).
COEFFICIENT OF PERMEABILITY - See PERMEABILITY.
COHESION - that part of soil strength that is present independently of any
applied pressures, either mechanical or capillary, and would remain, though
not necessarily permanently, if all applied pressures were removed.
COMPACTION - Compression of a mass to decrease its volume or the thickness
of a layer by reduction of voids.
DARCY'S LAW - A law describing the rate of flow of water through porous
media.
DISPERSED STRUCTURE - A soil structure wherein the clay particles are asso-
ciated primarily in a random, parallel array. i
434
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DOUBLE LAYER - In colloid chemistry, the electric charges on the surface
of the disperse phase (usually negative), and the adjacent diffuse layer
(usually positive) of ions in solution (SSSA, 1970).
EXCHANGEABLE SODIUM PERCENTAGE - The extent to which the absorption complex
of a soil is occupied by sodium. It is expressed as follows:
_ Exchangeable sodium (meq/lOOg soil)
Cation-exchange capacity (meq/lOOg soil)
FLOCCULATED STRUCTURE - A soil structure wherein the clay particles are
associated, primarily in a random, predominantly edge-to-face arrangement with
essentially solid contact in the areas of closest approach.
GRAVITATIONAL WATER - Water which moves into, through, or out of the soil
under the influence of gravity.
HYDRAULIC CONDUCTIVITY - See "Permeability".
ILLITE - A major group of clay minerals having the crystalline structure of
hydrous mica.
I i
INFILTRATION RATE (INFILTRATION CAPACITY) - A soil characteristic'determining*
the maximum rate at which water can enter the soil under specified condition'Syi
including the presence of an excess of water. It has the dimensions of veldq-i
ity (SSSA, 1970). t \
»
INFILTRATION VELOCITY - The actual rate at which water jjj_ entering the soil
at any given time. It may b~e less than the maximum (the infiltration rate)
because.of a limited supply of water (rainfall or irrigation). It has the
same units as infiltration rate (SSSA, 1970).
INTRINSIC PERMEABILITY - The property of a porous material that relates
to the ease with which gases or liquids can pass through it. The Darcy -IK"
is multiplied by n'/g to obtain K1, the intrinsic permeability, where:
n' is the kinematic viscosity of the fluid in cm^ see"*
g is the acceleration of gravity in cm/sec^
n1 » n/p
where, n is viscosity in poises, g cm"1 sec
p is density of the fluid in g cm
For water at 23°C and g = 981 cm sec"1, the relationship between
permeability, K, and intrinsic permeability K1 is expressed by the
equation
K1 * (0.91 x ID'5 cm sec)(K)
INTERLAYER - Materials between layers, including cations, hydrated cations,
organic molecules and hydroxide groups or sheets. Refers to clay mineralogy
microstructure (SSSA, 1970).
435
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INTERLAYER (OR BASAL) SPACING - The space between layers in clay microstruc-
ture.
ISOMORPHOUS SUBSTITUTION - The replacement of one atom by another of similar
size and lower charge (valance) in crystal lattice without significantly
disrupting or changing the crystal structure of the mineral (SSSA, 1970).
ISOTROPIC SOIL - A soil in which a certain property at a point is the same
in all directions through that point.
KAOLIN - (1) An alumino-silicate mineral of the 1:1 crystal lattice group;
that is, consisting of one silicon tetrahedral layer and one aluminum oxide-
hydroxide octahedral layer. (2) The 1:1 group or family of alumino-silicates
(SSSA, 1970).
LOAM - A textural class name for soil having a moderate amount of sand,
silt, and clay. Loam soils contain 7-28% clay, 28-50% silt, and less than 52%
sand (Brady, 1974).,
MOISTURE CONTENT - The weight loss (expressed in %) when a sample of soil or ;.
waste is dried to a constant weight at 100-105°C (EPA, 1972). , .ji
MOISTURE CONTENT, OPTIMUM - The water content at which a soil-like ma-ss < fv
can be compacted to a maximum dry unit weight oy a given comoactive effort. "• ]
MOISTURE RETENTION CURVE - A graph showing the soil moisture percentage
(by weight or by volume) versus applied tension. Points on the graph are
obtained by increasing or decreasing the applied tension over a 'specified
range (SSSA, 1970).
MOISTURE TENSION (OR PRESSURE) - The equivalent negative pressure in the soil
water. It is the equivalent pressure that must be applied to the soil water
to bring it to hydraulic equilibrium, through a porous permeable wall or
membrane, with a pool of water of the same composition (SSSA, 1970).
MOISTURE-WEIGHT PERCENTAGE - The moisture content expressed as a percentage
of the oven-dry weight of soil (SSSA, 1970).
MONTMORILLONITE - An alumino-si1icate clay mineral with a 2:1 expanding
crystal structure; that is, with two silicon tetrahedral layers enclosing
an aluminum octahedral layer. Considerable expansion may be caused along
the axis by water moving between the silica tetrahedra of neighboring layers.
OVENDRY SOIL - Soil which has been dried at 105°C until it reaches a con-
stant weight (SSSA, 1970).
PARTICLE DENSITY - The mass per unit volume of the soil particles. In tech-
nical work, usually expressed as g/crrr (SSSA, 1970)-.
PARTICLE -SIZE - The effective diameter of a particle measured by sedimenta-
tion, sieving, or micrometric methods (SSSA, ly'/uj.
436
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PARTICLE SIZE DISTRIBUTION - The amounts of the different soil particles
in a soil sample, usually expressed in weight percentages (SSSA, 1970).
PERCOLATION, SOIL WATER - Downward movement of water through soil. Especi-
ally, the downward flow of water in saturated or near saturated soil at hy-
draulic gradients of the order of 1.0 or less (SSSA, 1970) (ASTM, D653,
1979).
PERMEABILITY - A numerical measure of the ability of a soil to transmit
a fluid (typically water). Permeability, K, is a constant of proportionality
uder conditions of laminar flow, such that the Darcy relationship is valid.
Permeability has dimensions of velocity, i.e. cm sec"1-.
PLASTICITY INDEX (PLASTICITY NUMBER) (PLASTICITY RANGE) - The numerical
difference between the liquid limit and the plastic limit.
PLASTIC LIMIT - See Atterberg limits.
PLATY - Consisting of soil aggregates that are aeveloped predominantly along
horizontal axes; laminated, flaky (SSSA, 1970).
PORE-SIZE DISTRIBUTION - The volume of various sizes of pores in a soil;.,
Expressed as a percentage of bulk volume, i.e., total volume of solids and».
pores (SSSA, 1970). if
«'.$
POROSITY - The volume percentage of the total bulk not occupied by soliij*
particles (SSSA, 1970). ' . ] [
POTASSIUM FIXATION - The process of converting exchangeable to no-nexchange-
able potassium (adapted from SSSA, 1970).
PROCTOR (COMPACTION TEST) - Standard proctor or standard AASHTO test used
to determine the proper amount of mixing water to use when compacting a
soil test in the field and the resulting degree of density which can be
expected from compaction at this optimum water content (Lambe, 1951).
SAND - Coarse grain soils of which more than half of the coarse fraction is
smaller than 4.75 mm sieve size (Unified Soil Classification).
SANDY LOAM - A soft easily worked soil containing 0-20% clay, 0-5% silt
and 43-85% sand according to the US Department of Agriculture (EPA, 1972).
SHRINK/SWELL - Volume change cfue to build-up and release of capillary tensile
stress within the soil's pore water (Asphalt Institute, MS-10).
SILT - (1) Soil particles which pass through a No. 200 sieve and are larger
than 0.002 mm in equivlant diameter. (2) Soil textural class (Brady, 1974).
SMECTITE - See Montmorillonite.
SOIL - The unconsolidated natural surface material present above bedrock;
either residual in origin (formed by the in-place weathering of bedrock) or
placed by the wind, water, or gravity (EPA, 1972).
437
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SOIL PIPING OR TUNNELING - Accelerated erosion which results in subterranean
voids and tunnels (SSSA, 1970). M
SOIL SOLUTION - Tne aqueous liquid phase of the soil and its solutes consist-
ing of ions dissociated from the surfaces of the soil particles and of other
soluble materials (Brady, 1974).
SOIL STRUCTURE - The combination or arrangement -of primary soil particles
info secondary particles, units, or peds. These secondary units may be, but
usually are not, arranged in the profile in such a manner as to give a dis-
tinctive characteristic pattern. The secondary units are characterized and
classified on the basis of size., shape, and degree of distinctness into
classes, types, and grades, respectively (SSSA, 1970).
SOLUM - The upper and most weathered part of the soil profile; the A and B
horizons (SSSA, 1970).
SURFACE SEALING - The orientation and packing of dispersed soil particles
in the immediate surface layer of the soil, rendering it relatively imperme-
able to water (SSSA, 1970)1 ; '
1 ^
TACTOID - An agglomeration of clay particles. 'v-'
'
TEXTURE - The relative proportions, of various particle size classes (clay, }
silt, sand) in a soil (Brady, 1974),. ' '•
THIXOTROPY - An isothermal, reversible, time-dependent process occurring
under conditions of constant composition and volume whereby a material stif-
fens while at rest and softens or liquifies upon remolding (Mitchell, 1960).
UNSATURATED FLOW - The movement of water in a soil which is not filled to
capacity with water (SSSA, 1970).
VOID RATIO - Volumetric proportion in a bulk volume of soil between voias
and sol id soi1.
WATER STABLE AGGREGATE - A soil aggregate which is stable to the action
of water such as falling drips or agitation, as in wet sieve analysis (SSSA,
1970).
4
^•38
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GLOSSARY
SOLID WASTE MANAGEMENT
AQUIFER - See Hydrology Glossary..
BIODEGRADABLE - See Hazardous Waste Glossary.
8005 - See Chemistry Glossary.
CELL - Portion of waste in a landfill which is isolated horizontally and
vertically from other portions of waste in the landfill by means of soil
barrier (Fed. Regist., 1973).
', i
COD - See Chemical Glossary. . .«.
COLLECTION SYSTEM - See Hazardous Waste Glossary. ' i IN-
COMPATIBILITY - See Hazardous Waste Glossary. ' \
COVER, DAILY - The cover material that is applied over compacted wastes in
a working landfill at the end of each operating clay.
DENSITY -
Sanitary Landfill: Ratio of the combined weight of solid waste and
the soil cover to the combined volume of the solid waste and the
s'oil cover:
WSW + wsoil
Solid Waste: The number obtained by dividing the weight of solid, waste
by its volume (EPA, 19?2).
EFFLUENT (1) A liquid which flows out of a containing space; (2) Sewage
water or other liquids partially or wholly flowing out of a reservoir basin
or treatment plant or part therof (EPA, 1977).
FACILITY - Any land or appurtenances thereon and thereto, used for treat-
ment, storage and/or disposal of hazardous waste (Fed. Regist., 1978).
FIELD CAPACITY - The. maximum amount of moisture a soil or solid waste can
retain in a gravitational field without a continuous downward percolation
(Fenn et al, 1975).
439
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IMPERMEABLE- Not permitting passage of a fluid or a gas through its substance.
IMPERVIOUS - See "Impermeable".
INDUSTRIAL WASTE - See Hazardous Waste Glossary.
LEACHATE - Liquid that has percolated through or drained from hazardous
waste or.other man-emplaced materials and contains soluble, partially soluble,
or miscible components removed from such waste (Fed. Regist., 1978). Primary
leachate, as used in this document is that liquid originating in the waste;
secondary leachate is that liquid which enters the waste and percolates
through.
LINER - A layer of emplaced materials beneath a surface, impoundment, or
landfill which serves to restrict the escape of waste or its constituents
from the impoundment or landfill (Fed. Regist., 1978). In this Technical
Resource Document, a liner includes: reworked or compacted soil and clay,
asphaltic and concrete materials, spray-on membranes, polymeric membranes,
chemisorptive substances, or any substance that serves the above stated
purpose.
LYSIMETER - A device used to measure the quantity or rate of water movement
through or from a block of soil or other material, such as solid waste,
or used to collect percolated water for qualitative analysis (EPA, 1972).
MONITORING WELL - See Hazardous Waste Glossary.
MUNICIPAL SOLID WASTE - Solid waste collected from residential and commercial
sources in bins and other large containers. Typical components are: plant
matter, 1%; paper products, 56%; food wastes, 9%; metals, 8%; ceramics and
glass, 8%; plastic , leather, and rubber, 4%; wood, rags, etc.; 7%.(Baum
and Parker, 1974).
PESTICIDE - A broad term that includes all cnemical agents used to kill animal
and vegetable life which interfere with agricultural productivity, regardless
of their mode of action (Hampel and Hawley, 197b).
pH - See Chemistry Glossary.
POLLUTANT - (1) A substance, material, .nemical, etc., that renders the
carrier medium, i.e.., a solid, liquid, or gas, unfit for industrial or domes-
tic use, or presents a potential public health hazard. (2) In this Technical
Resource Document, a pollutant is a substance or material that degrades the
quality of, or, directly or indirectly, presents a hazard to all or any of the
following sectors of the environment: water, groundwater, air, soil, plants,
wildli fe, or people.
RUN-OFF - See Hydrology Glossary.
SANITARY LANDFILL (LAND FILLING) - A site where solid waste is disposed of on
land in a" manner that protects the environment by spreading the waste in thin
layers, compacting it to the smallest practical volume, and then covering it
with soil by the end of the working day (EPA, 1972).
i
440
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SANITARY LANDFILLING METHODS - Area, Quarry, Ramp, Trench, and Wet Areas,
Area:
Quarry:
Ramp:
Trench:
Wet Area:
A method in which the wastes are spread and compacted on
the surface of the ground and cover material is spread and
compacted over them.
Wastes are spread and compacted in a
terial is generally obtained elsewhere.
depression; cover ma-
Cover material is obtained by excavating in front of the
working area. A variation of this method is known as the
progressive slope sanitary landfilling method.
Waste is spread and compacted in a trench; the excavated
soil is spread and compacted over the waste to form the basic
eel 1 structure.
Used in a swampy area where precautions are taken to avoid
water pollution before proceeding with the area method
(EPA, .1972).
SOLID WASTE - Any garbage, refuse, or sludge from a waste treatment plant;,,
water supply treatment plant, or air pollution control facility, and oth,er>.
discarded material, including solid, liquid, semisolid, or contained gasedijs.,
material resulting from industrial, commercial, mining, and agricul tuna$',-
operations, and from community activities; does not include solid or dissolve^*
material in domestic sewage, or solid or dissolved materials in irrigation'
return flows or industrial discharges (Public Law, 1976).
SOLID WASTE MANAGEMENT - The purposeful, systematic control of the generation,
storage, collection, transportation, separation, processing, recycling,
recovery, and disposal of solid waste (EPA, 1972).
SUSPENDED SOLIDS - See Chemistry Glossary.
TOE - Bottom of any slope, specifically applied in this Manual to the bottom.
of the working face of a landfill.
VECTOR - A carrier, e.g. an insect or a rodent, that is capable of transmit-
ting a pathogen from one organism to another (ASCE, 1976).
VOLATILE ACIDS - See Chemi stryr G1 ossary.
VOLATILE MATTER - The matter lost from a dry solid waste sample that is
heated until it is red in a closed crucible (EPA, 1972).
VOLATILE SOLIDS - Chemistry Glossary.
WATER TABLE - See Hydrology Glossary.
WORKING FACE - That portion of a sanitary landfill where waste is discharged
by collection trucks a^nd is compacted prior to placement of cover material
(EPA, 1972).
441
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REFERENCES
GLOSSARY
APHA-AWWA-WPCF. 1975. Standard Methods for Examination of Water and Waste-
water. 14th ed. APHA, Washington, DC. 1193 pp.
ASCE. 1976. Sanitary Landfill. Manual of Practice No. 39. ASCE, New York, NY.
The Asphalt Institute. 1966. Drainage of Asphalt Pavement Structures. (MS-15).
College Park, MD. 136 pp.
The Asphalt Institute. 1967. Introduction to Asphalt. (MS-5). College Park, ''
MD, 84 pp. • \ j-^
'*•!•
The Asphalt Institute. 1969. Soil;; Manual for Design of Asphalt Pavement ' \\
Structures. (MS-10). College Park, MD. } '
The Asphalt Institute. 1976. Asphalt in Hydraulics. (MS-12). College Park, MD.
68 pp.
ASTM. Issued Annually. Annual Book of ASTM Standards. Several Parts. American
Society for Testing and Materials, Philadelphia, PA,.
ASTM. 1972. Glossary of Terms Relating to Rubber and Rubber Technology. STP
184A. American Society for Testing and Materials, Philadelphia, PA.
Baum, B., and C.H. Parker. 1974. Solid Waste Disposal, Volume 1: Incin-
eration and Landfill. Ann Arbor Science Publishers, Inc., Ann Arbor,
MI. 397 pp.
Bennett, H. , ed. 1947. Concise Chemical and Technical Dictionary. Chemical
Publishing Co., Inc., Brooklyn, NY. 1055 pp.
Brady, N.C. 1974. The Nature and Properties of Soil. 8t:h ed. MacMillan Pub-
lishing Co., Inc., New York, NY. 1055 pp.
Bureau of Reclamation. 1974. Earth Manual. U.S. Government Printing Office,
Washington, D.C. 810 pp.
Condensed Chemical Dictionary. 1974. 9th ed. Revised by Gessner G. Hawley.
Van Nostrand Reinhold Co., New York, NY. 957 pp.
Day, M.E. 1970. Brine Pond Disposal Manual. Contract 14-01-001-1306. Bureau of A
Reclamation, U.S. Department of the Interior, Denser, CO. 134 pp. . ^
442
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EPA. 1972. Solid Waste Management Glossary. SW-108ts. U.S. Environmental
Protection Agency, Washington, DC. 20 pp.
EPA. 1977. Supplement for Pretreatment to the Development Document for
the Steam Electric Power Generating Point Source Category. EPA 4401/
1-77-084. U.S. Environmental Protection Agency, Washington, DC. 253
pp.
Federal Register. 1978. Hazardous Waste - Proposed Guidelines and Regula-
tions and Proposal on Identification and Listing. Fed. Regist. 43 (243),
December 18, 1978.
Fenn, D.G., K.J. Hanley, and T.V. DeGeare. 1975. Water Balance Method
for Predicting Leachate Generation From Solid Waste Disposal Sites.
EPA 530/SW-168. U.S. Environmental Protection Agency, Washington, D.C.
40 pp.
Fuller, W.H. 1978. Investigation of Landfill Leachate Pollutant Attenuation
by Soils. EPA - 600/2-78-158. U.S. Environmental Protection Agency,
Cincinnati , OH. 218 pp.
Goodrich, B.F., Co. 1979. Technical RuDber Terms Glossary. B.F.
Chemical Division, Cleveland, OH. V-i ,
M |
Hampel , C.A., and G. G. Hawley. 1976. Glossary of Chemical Terms. Van Nostra.nd
Reinnold Co., New York, NY. 282 pp. ' '
Hornbostel , C. 1978. Construction Materials, Types, Uses, and Applications.
John Wiley and Sons, Inc., New York, NY. 878 pp.
Lambe, T.W. 1951. Soil Testing for Engineers. John Wiley and Sons, Inc.,
New York , NY. 165 pp.
Mitchell, J.K. 1960. Fundamental Aspects of Thixotropy in Soils. J. Soil
Mech. Found. Div., Am. Soc. Civ. Eng. 86(SM3): 19-52.
Public Law 94-580. 1976. Resource Conservation and Recovery Act of 1976.
Rubber Manufacturers Assn. 1969. Glossary of Industrial Rubber. Rubber Age.
101(10): 47-63.
Soil Science Society of America. 1970. Glossary of Soil Science Terms.
Madison, WI.
Webster's New Collegiate Dictionary.
Webster's New World Dictionary. .
Whittington, L.R. 1976. Whi tti ngton ' s Dictionary of Plastics. Technomic
Pub.. Co., line., Stamford, CT. 261 pp.
443
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Handbook. McSraw.H11, Book Co-i
«-
4
444
-------
SELECTED BIBLIOGRAPHY
CHAPTER 2. CHARACTERISTICS OF WASTES AND WASTE LIQUIDS
Battelle Memorial Institute. 1974. Program for the Management of Hazardous
Wastes. EPA Contract No. 63-01-0762. U.S. Environmental Protection
Agency, Richland, WA. 2 Vols. (PB-233-630; PB-233-631).
Booz Allen Applied Research Inc. 1973. A Study of Hazardous Waste Mat-
erials, Hazardous Effects and Disposal. Methods. U.S. Environmental
Protection Agency, Cincinnati, OH. Contract No. 63-03-0032. Los-
Angeles, CA. 3 Vols. (PB-221-464). ;,
•
EPRI. 1975. Environmental Effects of Trace Elements from Ponded Asn 4rk(
ScruDDer Sludge. EPRI-202. Electric Power Researcn Institute, Pa,"l$!
Alto, CA. i "v
j '
Federal Power Commission. 1977. Tne Status of Flue Gas Desul furization
Applications in the United States: A Technological Assessment. FPC.
80 pp.
Jones, J.W., J. Rossoff, R.C. Rossi, and L.J. Soornstein. 1974. Disposal
of By-Products from Non-Regenerable Flue Jas Desulfurization Systems.
Presented at the ASCE Annual and National Environmental Engineering
Conference.
CHAPTER 3. LINING MATERIALS AND LINING TECHNOLOGY
Bureau of Reclamation. 1967. Chapter of Lower Cost Canal Linings. In:
Annual Report of Progress on Engineering Research. Water Resources
Researcn Report No. 10. U.S. Oept. of Interior, Washington, DC.
^
Chan, P., J. Liskowitz, A.J. Perna, R. Trattner, and M. Sheih. 1978. Pilot
Scale Evaluation of Design Parameters for Sorbent Treatment of In-
dustrial Sludge Leachates. In: Land Disposal of Hazardous Wastes -
Proceedings of the Fourth Annual Research Symposium. EPA-600/
9-78-016. U.S. Environmental Protection Agency, Cincinnati, OH. pp.
299-318.
Fuller, W. H. 1977. Movement of Selected Metals, Asbestos and Cyanide in
-Soil: Applications to Waste Disposal Problems. EPA-600/2-77-020. U.S.
Environmental Protection Agency, Cincinnati, OH. 242 pp.
445
-------
SELECTED BIBLIOGRAPHY (continued)
€
Fuller, W. H. 1978. Investigation of -Landfill Leachate Pollutant Atten-
uation by Soils. EPA-600/2-78-158. U.S. Environmental Protection
Agency, Cincinnati, OH. (PB-286-995).
Hickey, M.E.' 1969. Investigation of Plastic Films for Canal Linings.
Water Resources Research Report No. 19. Bureau of Reclamation, U.S.
Dept. of Interior, Washington, DC. 35 pp.
Jones, C.W. 1971. Laboratory Evaluation of Canal Soil Sealants. REC-
ERC-71-1. Bureau of Reclamation, U.S. Dept. of Interior, Denver,
CO. 18 pp.
LeBras, J. 1965. Introduction to Rubber. MacLaren and Sons, Ltd., London.
105 pp.
Morrison, W.R. 1964. Evaluation of Sand-Phenolic Resin Mixtures as a Hard
Surface Lining, Lower Cost Canal Lining Program. Report No. B-36. >'
Bureau of Reclamation, U.S. Dept. of Interior, Denver, CO. 8 pp. • 4-<*
V'1
1976. New Membranes for Treating Metal Fin- »V;
erse Osmosis. FPA-600/2-76-19 7. U.S. En- .*' • !
Petersen, R. and K. Cobian.
ishing Effluents by Revei ._ ... .... , .. ,w .^,. „.„. _..
vironmental Protection Agency, Cincinnati, OH. 59 pp. (PB-265-363/ • {
2BE.111).
CHAPTER 4. LINING MATERIALS IN SERVICE ENVIRONMENTS
EPRI. 1978. Tne Impact of RCRA (PL 94-580) on Utility Solid Wastes. EPRI
FP-878. Electric Power Research Institute, Palo Alto, CA.
Geswein, A.J. 1975. Liners for Land Disposal Sites: An Assessment.
EPA/530/SW-137. U.S. Environmental Protection Agency, Washington, DC.
66 pp.
Haxo, H.E. 1976. Assessing Synthetic and Admixed Materials for Lining
Landfills. In: Gas and Leachate- from Landfills - Formulation, Col-
lection and Treatment. EPA'r-6C)0/9-76-004. U.S. Environmental Pro-
tection Agency, Cincinnati, OH. pp. 130-158. (PB-251-161).
Phillips, C.R. 1976. Development of a Soil-Waste Interaction Matrix.
EPS-4-EC-76. Environmental Protection Service, Environmental Con-
servation Directorate, Toronto, Canada. 89 pp.
Stall man, R. 1976. Aquifer-Test Design Observation and Data Analysis.
Book 3, Applications of Hydraulics. 81. U.S. Geological Survey,
Washi-ngton, DC.- 25 pp..
Styron, C.R. and Z.B. Fry. 1979. Flue Gas Cleaning Sludge Leachate/Liner *
446
-------
SELECTED BIBLIOGRAPHY (continued)
Compatibility Investigation - Interim Report. EPA-600/2-79-136. U.S.
Environmental Protection Agency, Cincinnati, OH. 78 pp.
Ware, S. and G. Jackson. 1978. Liners for Sanitary Landfills and Chemical
and Hazardous Waste Disposal Sites. EPA-600/9-78-005. U.S. En-
vironmental Protection Agency, Cincinnati, OH. 81 pp. P8-293-335/AS.
CHAPTER 5. DESIGN AND CONSTRUCTION OF LINED WASTE DISPOSAL FACILITIES
Duvel, W.A. 1979. Solid-Waste Disposal: Landfilling. Chem. Eng.
86(14):77-86.
Hass, J. and W. Lombardi. 1976. Landfill Disposal of Flue Gas Desul -
furization Sludge. Presented at the Third Symposium on Coal Utiliza-
tion, National Coal Association and Bituminous Coal Research, Inc.,,
Louisvi1le, KY. 13 pp.
Reid, G., L.E. Streebin, L.W. Canter, J.M. Robertson, and E. Klehro.
Development of Specification for Liner Materials for Use in Oi 1-Brina-'i
Pits, Lagoons and Otner Retention Systems. Draft Copy. Oklahoma^
Economic Development Foundation, Bureau of Water Resources Research^
Norman, OK. 35 pp. ' '
Thorton, D.E. and P, Blackall. 1976. Field- Evaluation of Plastic Film
Liners for Petroleum Storage Area in the Mackenzie Delta. EPS-3-
EC-76-13. Canadian Environmental Protection Service, Edmonton, Alberta,
Canada. 20 pp.
Weston, R.F., Inc. 1973. Pollution Prediction Techniques for Waste Disposal
Siting: A State-of-the-Art Assessment. EPA-SW-162C. U.S. Environmental
Protection Agency, Cincinnati, OH. 477 pp.
CHAPTER 6. MANAGEMENT, OPERATIONS, AND MAINTENANCE OF LINED WASTE
DISPOSAL FACILITIES
r
Everett, L.G. 1976. Monitoring Groundwater Methods and Costs. EPA-600/
4-76-023. U.S. Environmental Protection Agency, Cincinnati, OH. 140
pp. (PB257133/9BA).
McMillon, L.G. and J.W. Keeley. 1970. Sampling Equipment for Groundwater
Investigations. ^Groundwater. 8(3):10-15.
SCS Engineers. ' 1978. Investigation of Groundwater Contamination from Sub-
surface Sewage Sludge' Disposal. Vol. 1. Project Descriptions and
Findings, Final Report. EPA Contract No. 68-01-4166.
447
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SELECTED BIBLIOGRAPHY (continued)
448
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