United Slates
Environmental Protection
Agency
Office of Water and
Waste Management
Washington DC 20460
v>EPA
Lining of Waste
Impoundment and
Disposal Facilities
SW 870
September 1980
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LINING OF WASTE IMPOUNDMENT
AND DISPOSAL FACILITIES
by
Matrecon, Inc.
Oakland, California 94623
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
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DISCLAIMER
This report has been reviewed by the Municipal Environmental 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.
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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.:
Suren Dakessian
Michael A. Fong
Richard M. White
Emcon Associates, San Jose, California:
John G. Pacey
Southwest Research Institute, San Antonio, Texas:
David W. Shultz
Texas A and M University, College Station, Texas:
Kirk W. Brown
Also, Paul D. Haxo contributed in editing.
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Permit Writers Guidance Manual/Technical Resource Document
Preface
The land disposal of hazardous waste is subject to the requirements
of Subtitle C of the Resource Conservation and Recovery Act of 1976.
This Act requires that the treatment, storage, or disposal of hazardous
wastes after November 19, 1980, be carried out in accordance with a
permit. The one exception to this rule is that facilities in existence
as of November 19, 1980 may continue operations until final administrative
dispostion is made of the permit application (providing that the facility
complies with the Interim Status Standards for disposers of hazardous
waste in 40 CFR Part 265). Owners or operators of new facilities must
apply for and receive a permit before beginning operation of such a
facility.
The Interim Status Standards (40 CFR Part 265) and some of the
administrative portions of the Permit Standards (40 CFR Part 264) were
published by EPA in the Federal Register on May 19, 1980. EPA will soon
publish technical permit standards in Part 264 for hazardous waste
disposal facilities. These regulations will ensure the protection of
human health and the environment by requiring evaluations of hazardous
waste management facilities in terms of both site-specific factors and
the nature of the waste that the facility will manage.
The permit official must review and evaluate permit applications to
determine whether the proposed objectives, design, and operation of a
land disposal facility will be in compliance with all applicable pro-
visions of the regulations (40 CFR 264),
EPA is preparing two types of documents for permit officials
responsible for hazardous waste landfills, surface impoundments, and
land treatment facilities: Permit Writers Guidance Manuals and Technical
Resource Documents. The Permit Writers Guidance Manuals provide guidance
for conducting the review and evaluation of a permit application for
site-specific control objectives and designs. The Technical Resource
Documents support the Permit Writers Guidance Manuals in certain areas
(i.e. liners, leachate management, closure, covers, water balance) by
describing current technologies and methods for evaluating the performance
of the applicant's design. The information and guidance presented in
these manuals constitute a suggested approach for review and evaluation
based on best engineering judgments. There may be alternative and
equivalent methods for conducting the review and evaluation. However,
iv
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if the results of these methods differ from those of the EPA method,
their validity may have to be validated by the applicant.
In reviewing and evaluating the permit application, the permit
official must make all decisions in a well defined and well documented
manner. Once an initial decision is made to issue or deny the permit,
the Subtitle C regulations (40 CFR 124.6, 124.7 and 124.8) require
preparation of either a statement of basis or a fact sheet that discusses
the reasons behind the decision. The statement of basis or fact sheet
then becomes part of the permit review process specified in 40 CRF
124.6-124.20.
These manuals are intended to assist the permit official in arriving
at a logical, well-defined, and well-documented decision. Checklists and
logic flow diagrams are provided throughout the manuals to ensure that
necessary factors are considered in the decision process. Technical data
are presented to enable the permit official to identify proposed designs
that may require more detailed analysis because of a deviation from suggested
practices. The technical data are not meant to provide rigid guidelines for
arriving at a decision. References are cited throughout the manuals to pro-
vide further guidance for the permit official when necessary.
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FOREWORD
The Environmental Protection Agency was created because of increasing
public and government concern about the dangers of pollution to the health
and welfare of the American people. Noxious air, foul water, and spoiled
land are tragic testimonies 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 that necessary first 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 com-
munity 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 and
provides a most vital communications link between the researcher and the
user community.
This report was conceived and developed with the goal of providing a
comprehensive document that would be a useful tool for all interested and
involved parties who are participating in pollution control and management
activities. The above objectives have served as guiding principles for
which this document was prepared.
The following report describes and details the major aspects of liners
for hazardous waste impoundments. Various procedures are presented as to
the selection, manufacture, construction, and use of the major types of
liners.
Francis T. Mayo, Director
Municipal Environmental Research
Laboratory
VI
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TABLE OF CONTENTS
Page
AUKNUWLh
PREFACE
FOREWORD
LIST OF
LIST OF
CHAPTER
CHAPTER
2.1
2.2
2.3
2.4
2.5
UGMENTb
FIGURES
TABLES
1 . INTRODUCTION
2. CHARACTERISTICS OF WASTES AND WASTE FLUIDS
Introduction
Municipal Solid Waste (MSW)
2.2.1 Description of the Waste
2.2.2 Characteristics of Leachate from Municipal Solid Waste
2.2.3 Gas Production in MSW
2.2.4 Potential Pollution Effects of MSW Leachate
2.2.5 Potential Effects of MSW Leachate Upon Liners
Hazardous Wastes
2.3.1 Introduction
2.3.2 Pesticide Industry (SIC 287)
2.3.3 Soap and Detergent Industry (SIC 2841)
2.3.4 Paint Industry (SIC 285)
2.3.5 Inorganic Chemicals Industry (SIC 281)
2.3.6 Electroplating and Metals Finishing Industries (SIC 3471)
2.3.7 Petroleum Refining Industry
2.3.8 Rubber and Plastics Industry
2.3.9 Pharmaceutical Industry
Other Nonradioactive and Special Wastes
Discussion of Waste Fluids
References
m
iv
vi
xiv
xix
1
3
3
3
3
5
5
5
9
9
9
10
12
13
13
16
20
23
23
25
25
28
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Page
CHAPTER 3. LINING MATERIALS AND LINING TECHNOLOGY 31
3.1 Introduction 31
3.2 Soils and Clays 33
3.2.1 Introduction 33
3.2.2 Fundamental Properties of Soils 33
3.2.3 Engineering Characteristics of Soils and Clays 40
3.3 Admixed liners 49
3.3.1 Introduction 49
3.3.2 Hydraulic Asphalt Concrete (MAC) and Asphalt Panels 49
3.3.3 Soil Cement 53
3.3.4 Soil Asphalt 54
3.4 Flexible Polymeric Membranes 54
3.4.1 Introduction 54
3.4.2 Description of the Polymeric Liner Industry 54
3.4.3 Polymers Used In Liner Manufacture 58
3.4.4 Membrane Manufacture 65
3.5 Sprayed-on Linings 69
3.5.1 Introduction 69
3.5.2 Air-blown Asphalt 69
3.5.3 Membranes of Emulsified Asphalt 71
3.5.4 Urethane-Modified Asphalt 71
3.5.5 Rubber and Plastic Latexes 71
3.6 Soil Sealants 72
3.7 Chemical Absorptive Liners 74
References 75
CHAPTER 4. LINING MATERIALS IN SERVICE ENVIRONMENTS 81
4.1 Introduction 81
4.2 Effects of Waste Fluids on Soil 82
4.2.1 Discussion of Waste Fluids in Contact with Soils 82
4.2.2 Waste Fluids 82
4.2.3 Solvent Phase of the Waste Fluids 83
4.2.4 Dissolved Components in Waste Fluids 85
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Page
4.3 Effects of Waste Fluids on Soils - Failure Mechanisms 87
4.3.1 Dissolution of Clay 87
4.3.2 Volume Changes in the Soil 88
4.3.3 Piping 97
4.3.4 Alteration of the Permeability of "As-Compacted" Soil 99
4.3.5 Slope Stability 99
4.3.6 Miscellaneous 100
4.4 Effects of Waste Fluids on Flexible Polymer Membrane Liners 101
4.4.1 Introduction 101
4.4.2 Exposure of Membrane Liners to Sanitary Landfill
Leachate 102
4.4.3 Exposure of Membrane Liners to Hazardous Wastes 107
4.4.4 General Discussion of Results 120
4.5 Effect of Waste Fluids on Admix and Other Liner Materials 123
4.5.1 Exposure to Municipal Solid Waste Leachate 123
4.5.2 Exposure to Hazardous Wastes 123
4.6 Compatibility of Liner Materials in Waste Fluids 126
4.6.1 Introduction 126
4.6.2 Screening of Liner Materials Based Upon
State-of-the-Art Knowledge 126
4.6.3 Testing of Specific Combinations of Liners and Wastes 128
4.7 Failure Mechanisms and Estimating Service Lives 131
4.7.1 Physical Failures 131
4.7.2 Biological Failures 134
4.7.3 Chemical Failures 134
References 135
CHAPTER 5. DESIGN AND CONSTRUCTION OF LINED WASTE FACILITIES 141
5.1 Introduction 141
5.1.1 Types of Constructed Impoundments 142
5.1.2 Site Planning Considerations 146
5.2 Disposal Facilities With Liners of Soils and Clays 147
5.2.1 General Discussion 147
5.2.2 Testing of Soil for Selection and Design of Liner 149
5.2.3 Designing of Soil and Clay Liners 157
5.2.4 Excavation and Embankment Construction 160
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5.2.5 Quality Control 168
5.2.6 Construction of Bentonite-Clay Liner 168
5.3 Disposal Facilities With Linings of Admixed Materials 170
5.3.1 Introduction 170
5.3.2 Soil Cement and Portland Cement Concretes 171
5.3.3 Concrete and Cement 171
5.3.4 Asphalt Concrete 173
5.3.5 Asphalt Panels 173
5.4 Design and Construction of Flexible Membrane Liner Installations 176
5.4.1 Introduction 176
5.4.2 Planning and Design Considerations for Membrane Liners 176
5.4.3 Preparation of Subgrade for Flexible Membrane Liners 181
5.4.4 Liner Placement 186
5.4.5 Quality Control 186
5.4.6 Earth Covers for Flexible Membrane Liners 189
5.4.7 Coupon Testing and Evaluation 193
5.4.8 Gas Venting 193
5.5 Placement of Miscellaneous Types of Liners 194
5.5.1 Sprayed-On Liners 194
5.5.2 Placement of Soil Sealants 195
5.5.3 Placement of Chemisorptive Liners 195
5.6 Liners and Leachate Management for Solid Waste Landfill 195
5.6.1 Environment of the Liner in a Sanitary Landfill 195
5.6.2 Estimating Leachate Volume 197
5.6.3 Transmissivity of Leachate 203
5.6.4 Leachate Collection System Network 207
5.6.5 Leachate Withdrawal and Monitoring Facilities 207
5.6.6 Covers and Closure of Lined Waste Impoundments 209
References 211
Chapter 6. MANAGEMENT, OPERATIONS, AND MAINTENANCE OF LINED WASTE
DISPOSAL FACILITIES 216
6.1 Introduction 216
6.2 Standard Operating Procedures for the Impoundment 216
6.3 Information on the Design, Construction, and Materials
of Construction 217
6.4 Control of Incoming Waste 217
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6.5 Monitoring the Performance of the Impoundment 218
6.6 Monitoring the Liner 219
6.7 Condition of Earthwork 219
6.7.1 Vegetation Control 219
6.7.2 Rodent Control 219
6.8 Inspection of Appurtenances 219
6.9 General Comments 219
6.10 Unacceptable Practices 220
References 221
CHAPTER 7. LINER COSTS FOR LINED WASTE DISPOSAL FACILITIES 222
7.1 Introduction 222
7.2 Capital Costs 222
7.3 Annual Cost Items 226
7.4 Case Study Methodology for Analyzing Cost 226
CHAPTER 8. SELECTION OF A LINER MATERIAL FOR A WASTE DISPOSAL FACILITY 227
8.1 Introduction 227
8.2 The Function of the Waste Disposal Facility 228
8.3 Soils on Site 228
8.4 Hydrology 228
8.5 Significant Environmental Factors 229
8.6 Acceptable Flow Through a Liner 229
8.7 Review of Available Materials 229
8.8 Cost of Liner Materials 229
8.9 Compatibility Tests 229
8.10 Selection of Liner Material 229
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Page
CHAPTER 9. SPECIFICATION FOR CONSTRUCTION OF LINED WASTE IMPOUNDMENTS 231
9.1 Introduction 231
9.2 Specifications for Construction 231
9.3 Materials Specifications 233
References 235
APPENDIX I UNIFIED SOIL CLASSIFICATION 236
APPENDIX II REPRESENTATIVE LIST OF ORGANIZATIONS IN LINER INDUSTRY 237
II-A Polymeric Membrane Liners 238
II-A.l Polymer Producers 238
II-A.2 Manufacturers of Polymeric Membrane Sheetings 239
II-A.3 Fabricators of Liners 241
II-A.4 Installing Contractors 242
II-B Bentonite Producers and Suppliers 244
II-C Other Liner Materials 245
II-D Miscellaneous Organizations in the Liner Industry 245
APPENDIX III SELECTED LINER TEST METHODS 247
III-A Immersion Test of Membrane Liner Materials for
Compatibility with Wastes 248
III-B Pouch Test for Permeability of Polymeric Membrane Liners 253
III-C Tub Test of Polymeric Membrane Liners 260
III-D Test Method for the Permeability of Compacted Clay Soils
(Constant Elevated Pressure Method) 264
APPENDIX IV INSTALLATION OF FLEXIBLE POLYMERIC MEMBRANE LINERS 270
IV.1 On-Site Storage of Materials and Equipment 270
IV.2 Installation Equipment 270
IV.3 Manpower Requirements 278
IV.4 Liner Placement 278
IV.5 Field Seaming 280
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IV-6 Anchoring/Sealing Around Structures/Penetrations 292
APPENDIX V LEACHATE COLLECTION SYSTEM NETWORK 300
VI.1 Flow Capacity 300
VI.2 Structural Stability of Pipe 303
V.2.1 Introduction 303
V.2.2 Loads Acting on Pipe 303
V.2.3 Deflection 308
V.2.4 Buckling Capacity 311
V.2.5 Compressive Strength 311
V.2.6 Construction Loadings 311
V.2.7 Procedures for Selection of Pipe Strength 312
APPENDIX VI SWELL BEHAVIOR OF SOILS AND CLAYS 315
APPENDIX VII SYSTEM ANALYSIS AND OPTIMIZATION OF SOIL LINER DESIGN 320
APPENDIX VIII CASE STUDY ANALYSIS METHODOLOGY 330
APPENDIX IX SPECIFICATIONS FOR FLEXIBLE POLYMERIC MEMBRANE MATERIALS 334
GLOSSARY OF TERMS RELATING TO LINER TECHNOLOGY 351
1 Admix Liner Materials 352
2 Asphalt Technology 353
3 Chemistry 355
4 Hazardous Wastes Management 358
5 Hydrology 360
6 Polymeric Membrane Liners 362
7 Site Construction 368
8 Soils Science and Engineering 371
9 Solid Waste Management 377
References 381
SELECTED BIBLIOGRAPHY 383
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LIST OF FIGURES
Page
2-1. Summary of total quantities of waste from paint and coatings
industry. 14
2-2. Toxic chemical compounds in waste generated by the paint
industry. 15
3-1. Relative permeability values for three clays. 36
3-2. Attenuation of polluting species by soil liners of different
absorptive capacities. 38
3-3. The rates of contamination of soil liners- 38
3-4. Basic structure of the polymeric membrane liner industry. 55
3-5. Roll configuration on calenders. 66
3-6. Calender arrangement - sheeting. 67
3-7. Nylon-reinforced butyl lining samples. 68
4-1. Landfill simulator used to evaluate liner materials exposed
to sanitary landfill leachate. 103
4-2. Base of the landfill simulator in which the liner materials
were exposed. 104
4-3. Swelling of membrane liners during immersion in leachate
for 8 and 19 months. 109
4-4. Retention of tensile strength of polymeric membrane liners
on immersion in landfill leachate after 8 and 19 months. 109
4-5. Retention of average tensile strength of membrane liner
materials during immersion in landfill leachate as a func-
tion of swelling by the leachate. 110
4-6. Exposure cells for membrane liners. 112
4-7. Exposure cells for thick liners. 112
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Page
4-8. Schematic representation of the movements of the mobile
constituents in the pouch (bag) test. 118
4-9. Types of swelling of polymeric membranes. 122
5-1. An excavated impoundment. 143
5-2. Diked pond partially excavated below grade. 144
5-3. A cross-valley pond configuration. 145
5-4. Schematic representation of the relationships w-p,
w-K, and p-K, Case 1. 159
5-5. Schematic representation of the relationships w-p,
w-K, and p-K, Case 2. 161
5-6. Typical earthwork equipment. 163
5-7. Trenching machine for anchor trenches (top). Dozer and earth
mover for berm construction (bottom). 164
5-8. Conveyor system used during impoundment construction. 165
5-9. Typical compaction equipment. 169
5-10. Water vehicles used to prepare the soil for compaction. 170
5-11. Steps in the installation of a soil-cement liner. 172
5-12. Placing of hydraulic asphalt concrete liner. 174
5-13. Installation of asphalt panel linings in canals. 175
5-14. Photographs showing various stages of subgrade finishing. 183
5-15. Scraper and roller being used to fine finish a subgrade. 184
5-16. Representative subgrade texture. 184
5-17. Salt grass penetrating a 30 mil flexible liner. 185
5-18. Two photographs showing bulldozers applying a soil cover
over membrane liners 192
5-19. A simplified representation of a gas vent for membrane
liners. 194
5-20. Schematic drawing of a lined sanitary landfill. 196
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Page
5-21. Percolation through solid waste and attenuation of leachate
by the soil environment. 201
5-22. Preclusion of leachate production through use of proper
drainage grades and cover soil. 202
5-23. Accumulation, containment, and collection of landfill
leachate. 203
5-24. Accumulation, containment, collection, and withdrawal of
landfill leachate showing saturation levels for different
conditions. 204
5-25. Selected characteristics of soils and waste fills. 205
5-26. Determination of leachate head on impervious liners using
flow net solution. 206
5-27. Typical inclined leachate monitoring and removal system. 209
5-28. Typical vertical leachate monitoring and removal system. 210
III-A-1. Suggested pattern for cutting test specimens. 251
III-B-1. Pattern for cutting pieces of membrane for making the bags. 255
III-B-2. Schematic of bag assembly, showing inner bag made of mem-
brane material under test. 257
III-B-3. Bag and auxiliary equipment for determining permeability. 258
III-B-4. Suggested pattern for dieing out test specimens. 259
III-C-1. The open exposure tubs lined with polymer membranes. 261
III-D-1. Modified compaction permeameter. 266
IV-1. Liner panels are shipped to the site on wooden pallets. 271
IV-2. Damage to a fabric reinforced liner caused by "blocking" of the
sheeting. 272
IV-3. High-density polyethylene (HOPE) is shipped to the site. 273
IV-4. Special equipment for seaming of high-density polyethylene. 274
IV-5. This crew is using a board for support under the area being
seamed. 275
IV-6. Sandbags are often used to anchor unseamed sheets of liner. 276
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IV-7. Heat guns are used to facilitate field seaming. 277
IV-8. The panels of liner membrane are unfolded or unrolled. 281
IV-9. Workmen "pull" the panel across the subgrade. 282
IV-10. Once a panel has been unfolded, the crew "spots" or positions
it in the proper location. 283
IV-11. Sandbags are placed along the edges to be seamed. 284
IV-12. The instructions for unrolling liner panels are clearly shown
on each container. 285
IV-13. Each panel must be pulled smooth. 286
IV-14. Sufficient seam overlap must be maintained. 287
IV-15. Typical factory seam and field seam lap jointed. 288
IV-16. The surfaces to be seamed must be cleaned to remove dirt. 289
IV-17. Seaming crews working with solvents are advised to use gloves
for protection. 290
IV-18. Field seaming. 291
IV-19. Rolling the seam. 292
IV-20. Repairing a wrinkle at the seams. 293
IV-21. Trench and backfill design for anchoring the perimeter of a
membrane liner at the top of the pond sidewalls. 294
IV-22. A commonly used flange type seal around penetrations. 296
IV-23. An example of a technique for sealing around penetrations using
the boot type method. 297
IV-24. Splash pad construction using a concrete subbase. 298
IV-25. Sluice type trough constructed of liner material. 299
IV-26. Typical design details for floating and fixed aeration systems. 299
V-l. Required capacity of leachate collection pipe. 301
V-2. Sizing of leachate collection pipe. 302
V-3. Pipe installation - conditions and loading. 304
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Number
Page
V-4. Projecting condition - pipe load coefficient. 305
V-5. Trench condition - pipe load coefficient. 307
V-6. Selection of pipe strength. 310
V-7. Typical leachate collection drains. 313
VI-1. Isoswell lines on moisture-density graph. 317
VII-1. Sketch of the flow system. 321
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LIST OF TABLES
Number Page
2-1. Composition and Analysis of an Average Municipal Refuse
from Studies by Purdue University 4
2-2. Leachate Parameters 6
2-3. Composition of Three MSW Landfill Leachates 7
2-4. Characteristics of MSW Leachate 8
2-5. Representative Hazardous Substances Within Industrial Waste Streams 11
2-6. Typical Plating Solutions 18
2-7. Characterization of Waste Stream Electroplating Industry 19
2-8. Hazardous Wastes Destined for Land Disposal from the Electroplating
and Metals Finishing Industry (Job Shops) 20
2-9. Ranges of Concentrations and Total Quantities for Refinery Solid
Wastes Sources 21
2-10. Raw Waste Constituents from the Pharmaceutical Industry 24
2-11. Trace Element Content of Samples from Coal Fired Electric Power
Generating Station 26
3-1. Classification of Liners for Waste Disposal Facilities 32
3-2. Typical Values for Properties of Kaolinite, Illite, and Montomoril-
lonite 34
3-3. Properties of Admix Liners Mounted as Barriers 51
3-4. Permeability of Asphalt Concrete to Water 52
3-5. Polymer Producers and Suppliers 57
3-6. Polymeric Materials Used in Liners 59
3-7. Representative Soil Sealants 73
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Number Page
4-1. Potential Organic Chemicals in Waste Fluids 84
4-2. Physical and Chemical Properties of the Clay Soils 89
4-3. Interlayer Spacings of Clay Organic Complexes on Montmorillonite 94
4-4. Interlayer Orientation and Interlayer Spacing in Montmorillonitic
Clay 95
4-5. Swell Potential vs. Atterberg Limit Values in Three Clay Soils 96
4-6. Testing of Polymeric Membrane Liners 103
4-7. Water and Leachate Absorption by Polymeric Liners 105
4-8. Analysis of Leachate 106
4-9. Swelling of Membrane Liners by Leachate 106
4-10. Retention of Modulus of Polymeric Membrane Liner Materials
on Immersion in Landfill Leachate 108
4-11. Wastes in Exposure Tests - Phases 111
4-12. Wastes in Exposure Tests - pH, Solids, and Lead 111
4-13. Volatiles and Extractables of Primary Polymeric Membrane
Liner Specimens after Exposure to Selected Wastes 114
4-14. Retention of Ultimate Elongation and S-100 Modulus of
Primary Polymeric Membrane Liner Specimens 115
4-15. Absorption of Waste by Polymeric Membrane on Immersion
in Selected Wastes 116
4-16. Volatiles Content of Flexible Polymeric Liners on
Immersion in Selected Wastes 117
4-17. Relative Permeabilities of Polymeric Membrane Lining
Materials in Pouch Test with Three Wastes 119
4-18. Permeability of Thermoplastic Polymeric Materials in
Osmotic Pouch Test 119
4-19. Pouch Test of Thermoplastic Membranes 120
4-20. Liner-Industrial Waste Compatibilities 129
4-21. Failure Categories 132
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Number Page
5-1. Factors to be Considered in the Site Planning/Construction
Process 146
5-2. Relevant Background Information Helpful During Site Selection
Process 148
5-3. Compaction Equipment and Methods
5-4. Moisture Content of Refuse 198
5-5. Summary of Water Balance Calculations 200
7-1. Capital Cost Items Relevant to Lined Waste Impoundment and
Disposal Facilities 223
7-2. Costs of Flexible Polymeric Membranes, Plastic, and Rubber
Liners 224
7-3. Cost Estimates of Soil, Admix Materials and Asphalt Membrane
Liners 225
9-1. Construction Procedures and Specification for Lined Waste
Disposal Facilities 232
III-A-1. Solvents for Extraction of Polymeric Membranes 249
III-B-1. Solvents for Extraction of Polymeric Membranes 254
III-C-1. Failed Elasticized Polyolefin Liner Exposed to Saturated and
Unsaturated Oils in Open Tub 263
IV-1. Equipment and Materials for Installation of Flexible Membrane
Liners 279
IV-2. Considerations During Liner Placement 280
VI I -1. Left Hand Side of Equation 3 323
VI I -2. Right Hand Side of Equation 3 323
VII-3. The Best and the Worst Combinations of Parameters Which Result in
nf « hd and hf « hj , respectively 324
VII-4. Left Hand Side of Equation 4 325
VII-5. Right Hand Side of Equation 4 325
VII-6. Left Hand Side of Equation 6 326
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Number Page
VII-7. Soil Liner Permeability Required to Restrict the Flux at
3"/Year 326
VII-8. Values of the Term [hdCq/Kf)-1^2 + 3*)] for Different
Values of h,j, A, Kf, and q 327
VIII-1. Design Criteria and Parameters 330
VIII-2. Capital Costs for Waste Impoundment Facility 332
VI 1 1 -3. Operating Costs for Impoundment Facility 332
VI 1 1 -4. Annual Cost for Impoundment Facility 333
IX-1A. Material Properties - Unsupported Polyvinyl Chloride (PVC) 335
IX-1B. Material Properties - Unsupported Chlorinated Polyethylene
(CPE) 336
IX-1C. Material Properties - Unsupported Butyl Rubber 337
IX-1D. Material Properties - Unsupported Polychloroprene (CR) 338
IX-1E. Material Properties - Unsupported High Density
Polyethylene (HOPE) 339
IX-1F. Material Properties - Unsupported Ethylene-Propylene
Diene Monomers (EPDM) 340
IX-1G. Material Properties - Unsupported Epichlorhydrin Polymers
(CO, ECO) 341
IX-1H. Material Properties - Unsupported Crossl inked Chlorinated
Polyethylene (XLCPE) 342
IX-1I. Material Properties - Unsupported Elasticized Polyolefin 343
IX-1J. Material Properties - Unsupported Chlorosulfonated
Polyethylene (CSPE) 344
IX-1K. Material Properties - Unsupported Oil Resistant Polyvinyl
Chloride (PVC-OR) 345
IX-2A. Material Properties - Supported Chlorinated Polyethylene
(CPER) 346
IX-2B. Material Properties - Supported Chlorosulfonated Polyethylene
(CSPER) 347
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Number Page
IX-2C. Material Properties - Supported Thermoplastic Nitrile-PVC 348
IX-2D. Material Properties - Supported Thermpolastic EPDM 349
IX-2E. Material Properties - Supported Elasticized Polyolefin Alloy 350
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CHAPTER 1. INTRODUCTION
The use of man-made materials of low permeability to line waste storage and
disposal impoundments has been demonstrated to be a feasible method of pre-
venting leachate and waste liquid components from leaking from an impoundment
and subsequently entering and polluting groundwater. These liner materials
can also be used to prevent the migration of dangerous concentrations of
methane and other gases from a waste containment site. A wide range of
materials is available from which to choose for the containment of specific
wastes.
This Manual is intended to provide information and guidance in the selection,
performance, installation.and maintenance of specific liners and cover
materials for specific containment situations, based upon the current state-
of-the-art of liner technology and other pertinent technologies.
Chapter 2 of this document contains descriptions and characteristics of
various types of wastes with reference to some of their polluting and
potentially polluting components. Several selected industrial waste streams
are described.
The various lining materials which are potentially useful and their associated
technologies are described 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 specific characteristics of liner materials in service environments with
various types of wastes are discussed in Chapter 4, particularly with respect
to their compatibility with wastes, their permeability to water and waste
constituents, failure mechanisms, and estimated service lives. Additional
waste characertization is presented for screening and selection purposes.
This chapter also introduces several testing procedures for evaluating the
waste/liner interaction.
The design and construction of waste facilities with the various types of
lining materials are described in Chapter 5 with particular emphasis on the
installation of membrane liners and the problems associated therewith.
Attention is given to the specific requirements for site and surface prep-
aration and placing of covers on membrane liners to prevent puncturing.
Special problems are associated with the design and construction of solid
waste disposal sites, i.e. solid waste landfills. The subject of leachate
collection above the liner is discussed.
The operation, management, and maintenance of disposal facilities having
different lining materials are described in Chapter 6. Particular attention
-------
is paid to the facilities that have membrane liners and groundwater
monitoring. A plan for monitoring the liners is suggested. Standard operating
procedures are discussed. Also included is a section on unacceptable
practices.
The historical costs of installing various liner materials for different types
of wastes are discussed in Chapter 7.
In Chapter 8, several parameters for selecting a specific liner or a group of
satisfactory liners for a given containment facility are presented. These
include the use of compatibility tests, moderate duration exposure tests, soil
condition tests, prior performance in similar facilities, costs, etc.
Methods for the preparation of proper specifications for selected liners or
groups of liners are suggested in Chapter 9.
At the end of each chapter of this document, a list of references from which
information is taken is presented. A bibliography is also presented for those
wishing to obtain additional information on specific subject topics.
In the appendixes, more detailed information is presented on specific subject
areas dealing mostly with development of the actual facilities. Appendix II
lists liner industry firms and organizations. A description of test methods
is presented in Appendix III. There are appendixes with detailed discussions
on the installation of flexible polymeric membrane liners, a leachate collec-
tion system network, swell behavior of soils and clays, optimization of soil
liner design and proposed specifications for flexible polymeric membrane
materials. In addition, a case study analysis methodology is presented for
lined impoundments. Because of the diverse origins of liner technology and
the broad spectrum of potential uses of this Manual, a glossary of terms used
in this Manual is included.
This Manual does not deal with the following subjects, except by reference:
1. Site selection, except when specific liners cannot be used.
2. Detailed discussion of methods of analysis of wastes, except for informa-
tion on waste components that are aggressive to linings of all types.
3. Monitoring of groundwater.
4. Attenuation of pollutants in the soil below the liner.
5. Legal aspects.
6. Final cover and closure.
This Manual attempts to bring together the 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 becomes available, this Manual will be
up-graded on a chapter-by-chapter basis.
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CHAPTER 2. CHARACTERISTICS OF WASTES AND WASTE FLUIDS
2.1 Introduction
From the standpoint of pollution and need for containment, it is the waste
fluids with which we are primarily concerned. They carry the dissolved
pollutants and have the capability of flowing and migrating out of a disposal
site. A polluting species in a solid waste must first dissolve into a liquid
before it can migrate through the ground. Furthermore, it is the fluid and
the dissolved constituents that can be aggressive to liner materials. Water,
itself, can be an aggressive constituent, causing the liner material to
swell. Consequently, the discussion in this chapter of the waste and waste
fluids is directed principally to the effects of wastes on liners.
The complexity of waste fluids, which include water, dissolved organic and
inorganic components, organic chemicals and solvents of great variety, and
bacteria, magnify the problems of containment.
The determination of the disposal requirements for wastes in lined facilities
is mandated by public law and enforced through EPA and state regulations.
Selected representative wastes of the following types are discussed:
- Municipal solid waste.
- Hazardous wastes from eight industries
- Other nonradioactive and special wastes.
The liner problems that are encountered with these waste streams should be
typical of those that must be solved generally. Also included in this chapter
is a section (2.5) concerned with the general properties of waste fluids,
particularly with respect to their potential interaction with liners. A more
complete discussion of the interaction of wastes and liners is given in
Chapter 4.
2.2 Municipal Solid Waste
2.2.1 Description of the Waste
Municipal solid waste (MSW) is that refuse from residential and commercial
sources that is usually collected from garbage cans and trash bins. Typical
components of municipal refuse include paper, glass, plastics, rubber, wood,
metal, food and garden wastes, ceramics, rocks, textiles, leather, etc. Major
components and rough wet weight percents are presented in Table 2-1 from Ham
et al. (1979). See Wigh (1979) for additional data. However, it is the
leachate generated within the waste that is of concern from the standpoint of
pollution and liner durability.
-------
Table 2-1. COMPOSITION AND ANALYSIS OF AN AVERAGE MUNICIPAL REFUSE FROM STUDIES BY PURDUE UNIVERSITY3
Percent
of all
refuse by
Component weight
Rubbish, 64%:
Paper
Wood
Grass
Brush
Greens
Leaves
Leather
Rubber
Plastic
Oils, paints
Linoleum
Rags
Street
sweepings
Dirt
Unclassified
Food wastes, 12%:
Garbage
Fats
Noncombustibles,
Metals
Glass & ceramics
Ashes
Composite refuse,
All refuse
42.0
2.4
4.0
1.5
1.5
5.0
0.3
0.6
0.7
0.8
0.1
0.6
3.0
1.0
0.5
10.0
2.0
24%:
8.0
6.0
10.0
Moisture
(percent
by
weight)
10.2
20.0
65.0
40.0
62.0
50.0
10.0
1.2
2.0
0.0
2.1
10.0
20.0
3.2
4.0
72.0
0.0
3.0
2.0
10.0
Analysis (percent dry weight)
Volatile
matter
84.6
84.9
• • *
• • •
70.3
• • •
76.2
85.0
• • •
65.8
93.6
67.4
21.2
• • •
53.3
• • •
0.5
0.4
3.0
Carbon
43.4
50.5
43.3
42.5
40.3
40.5
60.0
77.7
60.0
66.9
48.1
55.0
34.7
20.6
16.6
45.0
76.7
0.8
0.6
28.0
Hydrogen
5.8
6.0
6.0
5.9
5.6
6.0
8.0
10.4
7.2
9.7
5.3
6.6
4.8
2.6
2.5
6.4
12.1
0.04
0.03
0.5
Oxygen
44.3
42.4
41.7
41.2
39.0
45.1
11.5
22.6
5.2
18.7
31.2
35.2
4.0
18.4
28.8
11.2
0.2
0.1
0.8
Nitrogen
0.3
0.2
2.2
2.0
2.0
0.2
10.0
2.0
0.1
4.6
0.1
0.5
0.05
3.3
0.0
• • •
Sulfur
0.20
0.05
0.05
0.05
0.05
0.05
0.40
2.0
o!40
0.13
0.20
0.01
0.05
0.52
0.00
0.5
Non-
combus-
tibles
6.0
1.0
6.8
8 3
\j • \J
13.0
8.2
10.1
10 0
1 V • \J
10 2
1 \J • (-
16 3
\\J * \j
27 A
2.5
25.0
72 3
!(-•*)
62.5
16.0
0.0
99.0
99.3
70.2
as received:
100
20.7
• • •
28.0
3.5
22.4
0.33
0.16
24.9
a Ham et al., 1979.
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2.2.2 Characteristics of Leachate From Municipal Solid Waste
Leachate is liquid that has extracted, dissolved, or suspended organic and
inorganic materials from wastes as a result of percolation through the decom-
posing refuse.
The leachate produced from municipal refuse is a highly complex liquid mixture
of soluble, insoluble, organic, inorganic, ionic, nonionic, and bacteriolog-
ical constituents in an aqueous medium. It contains products of the degrada-
tion of organic materials and soluble ions which may present a pollution
problem to surface and ground waters (Phillips and Wells, 1974). The quality
of the leachate depends on the composition of the waste and the combined
physical, chemical, and biological activities.
The precise composition of leachate is, of course, waste and site specific,
depending on such variables as types of wastes, amount of infiltrating water,
and pH. Table 2-2 lists parameters of leachate which are used as analytical
indicators of landfill leachate in the groundwater near a landfill (EPA,
1977). Tables 2-3 and 2-4 present data to show the complexity in composition
of actual leachate from MSW, its site specific character and its variation
with time.
Griffin and Shimp (1978) compared the analyses of municipal landfill leachate
with drinking water standards. COD and BOD of landfill leachates were
generally high and the pH ranged from 4 to 9. Alkalinity, hardness,
phosphate, nitrogen, heavy metals, and concentrations of other elements were
also determined. The levels of these components varied over a very wide
range (Tables 2-3 and 2-4).
Leachates generated by the disposal of hazardous wastes may include high
concentrations of such heavy metals as mercury, cadmium and lead; toxic
substances, such as barium and arsenic; organic compounds, including chlor-
inated solvents, aromatic hydrocarbons, and organic esters; and various
corrosive, ignitable or infectious materials.
2.2.3 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.
Methane is of commercial value as a heating fuel and is being used in this
manner. Carbon dioxide is absorbed in leachate and tends to lower its pH and
thus to solubilize calcium, magnesium, iron, and other metals.
2.2.4 Potential Pollution Effects of MSW Leachate
Municipal landfill leachates degrade groundwater quality by introducing the
constituents shown in Tables 2-3 and 2-4 as well as biological contamination
(Phillips and Wells, 1974).
-------
TABLE 2-2. LEACHATE PARAMETERS3
Physical
Chemical
Organic
Inorganic
Biological
Appearance
PH
Oxidation-reduction
potential
Conductivity
Color
Turbidity
Temperature
Odor
Phenols
Chemical oxygen demand (COD)
Total organic carbon (TOC)
Volatile acids
Tannins, lignins
Organic-N
Ether soluble (oil and
grease)
MBAS
Organic functional groups
as required
Chlorinated hydrocarbons
Total bicarbonate
Solids (TSS, TDS)
Volatile solids
Chloride
Phosphate
Alkalinity and
acidity
Nitrate-N
Nitrite-N
Ammonia-N
Sodium
Potassium
Calcium
Magnesium
Hardness
Heavy metals (Pb, Cu,
Ni, Cr, Zn, Cd, Fe,
Mn, Hg, As, Se, Ba,
Ag)
Cyanide
Fluoride
Biochemical oxygen
demand (BOD)
Coliform bacteria
(total, fecal;
fecal streptococcus)
Standard plate count
a EPA, 1977.
-------
TABLE 2-3. COMPOSITION OF THREE MSW LANDFILL LEACHATES
Concentration of Constituents (mg/L)
Constituent
BOD5
COD
TOC
Total solids
Volatile suspended solids
Total suspended solids
Total volatile acids as acetic acid
Acetic acid
Propionic acid
Butyric acid
Valeric acid
Organic nitrogen as N
Ammonia nitrogen as N
Kjeldahl nitrogen as N
PH
Electrical conductivity (ymho/cm)
Total alkalinity as CaC03
Total acidity as CaC03
Total hardness as CaC03
Chemicals and metals:
Arsenic
Boron
Cadmium
Calcium
Chloride
Chromium
Copper
Iron
Lead
Magnesium
Manganese
Mercury
Nickel
Phosphate
Potassium
Silica
Sodium
Sulfate
Zinc
Wigh,
1979
• • •
42,000
• • •
36,250
. . .
t • •
• • •
• • •
• • *
• • •
• • •
950
1,240
6.2
16,000
8,965
5,060
6,700
• • •
• • •
• • •
2,300
2,260
• • •
• • •
1,185
> • .
410
58
...
. . .
82
1,890
...
1,375
1,280
67
Source of data
Breland,
1972
13,400
18,100
5,000
12,500
76
85
9,300
5,160
2,840
1,830
1,000
107
117
5.1
2,480
3,460
5,555
* • •
• • •
• * •
1,250
180
• * *
• • •
185
• • •
260
18
* • •
• • •
1.3
500
• • t
160
• • .
• • t
Griffin
and Shimp,
1978
• • •
1,340
• • •
• * •
• • •
333
• • •
• • •
• • •
• • •
• • •
862
6.9
• • •
• • •
• t •
0.11
29.9
1.95
354.1
1.95
<0.1
<0.1
4.2
4.46
233
0.04
0.008
0.3
• • •
f • •
14.9
748
<0.01
18.8
-------
CD
Constituent
BOD5
COD
Total dissolved solids
Total suspended
solids
Total nitrogen
PH
Electrical conduc-
wnho/cm)
Total alkalinity
as CaCC"3
Total hardness
as CaC03
Chemicals and Metals:
Cadimum (Cd)
Calcium (Ca)
Chloride (Cl)
Copper (Cu)
Iron (Fe)
Lead (Pb)
Magnesium (Mg)
Manganese (Mn)
Phosphate (P)
Potassium (K)
Sodium (Na)
Sulfate (S04)
Zinc (Znj
TABLE 2-4.
Rangeb
(mg/L)
9-54,610
0-89,520
0-42,276
6-2,685
0-1,416
3.7-8.5
• • •
0-20,850
0-20,800
• * •
5-4,080
34-2,800
0-9.9
0.2-5,500
0-5.0
16.5-15,600
0.6-1,400
0-154
2.8-3,770
0-7,700
1-1,826
0-1,000
CHARACTERISTICS OF MSW LEACHATES*
Range0
(mg/L)
• • •
100-51,000
• • •
• • •
20-500
4.0-8.5
—
200-5,250
• • *
• • *
100-2,400
• * *
200-1,700
• • •
• • •
* • »
5-130
• • •
100-3,800
25-500
1-135
Ranged
(mg/L)
7,500-10,000
16,000-22,000
10,000-14,000
100-700
...
5.2-6.4
6,000-9,000
800-4,000
3,500-5,000
0.4
900-1,700
600-800
0.5
210-325
1.6
160-250
75-125
• • »
295-310
450-500
400-650
10-30
Range6
(mg/L)
• • •
500-1,000
...
6.3-7.0
1,200-3,700
630-1,730
390-800
• • •
111-245
100-400
<0. 04-0. 11
20-60
• • •
22-62
1.02-1.25
21-46
107-242
106-357
13-84
<0. 04-0. 47
Leachatef
Fresh
14,950
22,650
12,620 1
327
989
5.2
9,200 1
• • •
2,136
742
0.5
500
• • •
277
49
7.35
• • .
• • •
. • •
45
Old
'si
,144
266
7.51
7.3
,400
• • •
254
197
0.1
1.5
• • •
81
...
4.96
...
• • .
• • •
0.16
a EPA-OSWMP, 1975. b EPA-OSWMP, 1973. c Steiner et al., 1971. d Genetelli and Cirello, 1976.
e Ham, 1975. f Brunner and Carnes, 1974.
-------
The quantity of leachate produced is a function of the moisture content of the
waste itself and the volume of water added through infiltration and percola-
tion from surface and ground sources. Leachate is being recycled in some
installations to enhance biodegradation in the landfill by providing nutrients
and water, thus reducing the quantity or quality of leachate produced and the
pollution potential. «
2.2.5 Potential Effects of MSW Leachate Upon Liners
The MSW leachate is not inert toward lining materials; constituents of the
leachate can affect liners in different ways, depending on their concentra-
tions in the leachate and on the specific liner materials. Furthermore, the
effects of the constituents can be synergistic and can vary with time as the
concentrations change with the aging of the waste. Dissolved salts and ions
may be damaging to some lining materials, particularly soils and clays.
Acidity or alkalinity may dissolve components of soils or soil cements.
Organic molecules (indicated by volatile acid content, volatile solid, and
COD) can be damaging to rubber and plastic liners causing them to swell,
to become more permeable and softer, thus to be more easily torn and damaged.
Water can cause some liners to swell, etc. These effects are discussed in
detail in Chapter 4. Also discussed in Chapter 4 is the need for compati-
bility testing when the waste fluid or leachate is known to contain con-
stituents that are particularly aggressive to some types of liner materials.
2.3 Hazardous Wastes
2.3.1 Introduction
Hazardous wastes disposed in land disposal facilities fall into four physical
classes:
1. Aqueous-inorganic
2. Aqueous-organic
3. Organic
4. Sludges, slurries, and solids (EPA-OSWMP, 1974)
Cheremisonoff et al. (1979) estimated that 90% (by weight) of industrial
hazardous wastes are produced as liquids. These liquids are further estimated
to be 40% inorganic and 60% organic (EPA-OSWMP, 1974).
Aqueous-inorganic is the class of wastes in which water is the solvent
(dominant fluid) and the solutes are mostly inorganic. Examples of these
solutes are inorganic salts, metals dissolved in inorganic acids, and basic
materials like caustic soda. Examples of wastes fitting in this category are
brines, electroplating waste, metal etching wastes, caustic rinse solutions,
and spent metal catalysts.
Aqueous-organic is the class of wastes in which water is the solvent and the
solutes are predominantly organic. Examples of these solutes are organic
chemicals that are polar or charged as is inferred by their water-solubility.
-------
Examples of this class of waste are wood preserving wastes, water base dye
wastes, pesticide container rinse water, and ethylene glycol production
wastes.
Organic is that class of wastes in which an organic fluid is the solvent or
dominant fluid and the solutes are the other organic chemicals dissolved in
the organic solvent. Examples of this class of wastes are oil base paint
waste, pesticide manufacturing wastes, spent motor oil, and spent cleaning
solvents.
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 a high solids content such as found in settled matter or
filter cakes and consists largely of clay minerals, silt, precipitates, fine
solids, and high molecular weight hydrocarbons. Examples of this waste are
American Petroleum Institute (API) separator sludge, storage tank bottoms,
treatment plant sludge or any filterable solid from any production or pollu-
tion control process.
Both economic and pollution control pressures continue to mandate solvent
recovery and reductions in discharges from aqueous waste streams. These
factors have and will continue to make sludges the fastest growing class of
wastes. After placement of sludges in a waste disposal facility, leachates
migrate out of the sludge due to gravitational forces, overburden pressures
and hydraulic gradients. These leachates are similar in physical form to the
first three classes of waste discussed.
Industrial wastes are a major source of hazardous waste, the components of
which are usually heavy metals, strong acids or bases, and a large array
of organic and inorganic chemicals. As shown in Table 2-5, taken from the EPA
Report to Congress on the disposal of hazardous wastes (EPA-OSWMP, 1974), each
industry produces wastes with different characteristics and components. Also,
wastes frequently vary with the source in the same industry. The chemical
nature and reactivity as well as concentration of the waste components must be
considered when choosing a liner for a given impoundment. The characteristics
of the wastes from several selected industries are discussed below, as
examples of specific wastes which may be encountered.
2.3.2 Pesticide Industry (SIC 287)
The diverse nature of the pesticide industry and its marketing strategy makes
it difficult to analyze and assess the impact of specific active ingredients
and their finished formulations. For example, there were some 24,000 differ-
ent formulations available from 139 manufacturers and 5,660 formulators as of
February 1976. Over 50,000 different products are said to have been register-
ed by the EPA. Each company that markets a given formulation of finished
pesticide must have a registered label for it. Over 3,500 companies hold
federal registrations for one or more products. In addition, many pesticides
are registered for intrastate sale only; an estimated 2,000 pesticidal pro-
ducts are registered in California alone (Wilkinson, 1978).
10
-------
TABLE 2-5. REPRESENTATIVE HAZARDOUS SUBSTANCES WITHIN INDUSTRIAL WASTE STREAMS
Hazardous substances
Chlorinated
Industry Arsenic Cadmium hydrocarbons3 Chromium Copper Cyanides Lead
Battery
Chemical manufac-
turing
Electrical and
electronic
Electroplating and
metal finishing
Explosives
Leather
Mining and metallurgy
Paint and dye
Pesticide
Petroleum and coal
Pharmaceutical
Printing and
duplicating
Pulp and paper
X
X
X
X
X
X X
X
X X
X X
X
X
X X
X X
XXX
XXX
X X
X
X X X X
X X X X
X X
X
XX X
X X
Mercury
X
X
X
X
X
X
X
X
Misc.
organicsb
X
X
X
X
X
X
X
X
Selenium Zinc
X
X
X X
X
X
V
Including polychlorinated biphenyls.
bFor example: acrolein, chloropicrin, dimethyl sulfate, dinitrobenzene, dinitrophenol, nitroaniline, and pentachloro-
phenol.
-------
Many pesticide and general biocide production wastes are aqueous solutions or
suspensions of organic and halogenated organic compounds. Some biocide wastes
are those from the production of: Dieldrin, Methylparathion, Dioxin, Aldrin,
Chlordane, ODD, DDT, 2,4-D, Endrin, Guthion, Heptachlor, and Lindane. Inor-
ganic based wastes result from the production of arsenic, arsenate, and
mercurial compounds. Thallium and thallium sulfate are found in rodenticide
wastes (EPA-OSWMP, 1974).
Pesticide wastes result largely from the periodic cleaning of formulation
rinf^Ai fV -9 eclulPment, spills, 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 waste. The scrubber waters
themselves are a waste stream with area washdown, leaks, and spills making UD
the remaining principal sources.
The principal constituents of wastewaters from the pesticide industry are
dissolved organics, suspended solids, dissolved inorganic solids, and variable
pH. As stated above, the great variety of manufactured end products
effectively precludes the presentation of a "general" waste composition chart
or table.
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
which case, the waste would most likely be partially treated, then r;~>,cen-
trated. The concentrated waste would be hauled to a landfill for disposal
or containerized and hauled to a landfill.
Concentrations of individual wastewater contaminants are frequently not
reported but the waste stream in general is characterized by COD, BOD,, TSS
TDS, and TOC (Becker, 1975). b
2.3.3 Soap and Detergent Industry (SIC 2841)
Another less dangerous, class of organic wastes are those from the soap and
detergent industries. Soap manufacturing produces a waste high in fatty
acids, lye, zinc, alkali earth salts, and caustic soda which are used as
catalysts and in neutralization. Glycerine is formed as a by-product of soap
production but much of this is recovered and recycled. Sulfuric acid and
sulfonic acid are used in the preparation of some soaps; the pH of the wastes
generated in these processes is very low. Soap production wastes also include
alcohols and alkylbenzenes. The waste stream is generally high in COD, BOD5,
TDS, acidity, oil and grease (Gregg, 1974). The EPA publication on soap and
detergent manufacturing (Gregg, 1974) is a good source of additional
12
-------
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.
2.3.4 Paint Industry (SIC 285)
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 spill, most of which is reclaimed and reused
except for paint absorbed onto 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 preparation 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. This 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 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. The solvent is then returned to the
plant for reuse.
Equipment used for water-thinned paints is cleaned with water and sometimes
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 and disposed into a landfill.
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 organic 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 (Figure 2-1). Figure 2-2 gives
the quantities of various components in the toxic waste stream. A detailed
list of waste components and quantities is available in the reference by
WAPORA, Inc. (1975).
2.3.5 Inorganic Chemicals industry (SIC 281)
The waste streams of a few of the specific industries in this category are
briefly described in this section.
13
-------
TOTAL V/ASTE
389,000
POTENTIALLY
HAZARDOUS
V/ASTE STREAM
96,000
HAZARDOUS
SOLVENTS
14,200
I I
TOTAL TOXIC
CHEMICAL
COMPOUNDS
841
100%
24.6%
3.6%
0.2%
Figure 2-1. Summary of total quantities of waste from paint and coatings
industry, wet weight in metric tons per year (WAPORA, 1975).
14
-------
841
r
o
o
z
&
u
VI
o
1 TOTAL HAZARD
246
o
UJ
s
2
O
K
X
O
91
! f 1 i i i i 1 i
18 |4 * ° " Z 0
rn nn r— i » i r-2-. 4^., ^±_ >
Figure 2-2. Toxic chemical compounds in waste generated by the paint indus-
try, wet weight in metric tons per year (WAPORA, 1975).
15
-------
The chlor-alkali industry, whose main product is chlorine, also produces
soda ash (NaOH) or 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 salable by-product. Those hazardous components not
reclaimed are usually disposed of in lined impoundment facilities (Hallowell
et al., 1976).
2.3.6 Electroplating and Metals Finishing Industries (SIC 3471)
Because of the heavy metal wastes from the electroplating and metal finishing
operations, all wastes from this industry are considered hazardous. The
electroplating industry can be classified into three principal segments:
plating, metal finishing, and the manufacture of printed circuit boards. The
plating segment can be further subdivided into: common metal electroplating,
precious metal electroplating and electroless plating. Subsegments of the
metal finishing category include: anodizing, chemical conversion coating,
chemical milling, etching and immersion plating (U. S. Department of Interior,
1980).
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 electroplaing
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.
16
-------
Wastewaters from plating and metal finishing operations are discharged from
all three phases of the electroplating process: 1) workpiece pretreatment; 2)
the plating, coating, or basis material removal process; 3) post treatment.
Wastewaters are generated by rinse water disposal, plating, or finishing bath
dumping, ion exchange (IE) unit regenerant bleed streams, vent scrubber
discharges, and maintenance discharges (U. S. Department of Interior, 1980).
Treatment may involve degreasing with soaps, alkaline 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 composi-
tions 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 2-6 lists some of the
various types of plating solutions used for electroplating. Plating solutions
for the metals in the platinum group are proprietary. The most common plating
solutions for electroless plating are copper and nickel, although iron,
cobalt, gold, palladium, and arsenic are also used. Of particular concern
among the constituents of electroless plating baths are the chelating agents,
which are used to hold the metal in solution (so the metal will not plate out
indiscriminately). There are three main types of chelating agents: amino
carboxylic acids, amines, and hydroxy acids. One of the drawbacks in the use
of chelating agents is the difficulty in precipitating chelated metals out of
wastewater during treatment.
Wastes from metal finishing operations comes from cleaning, pickling, anodiz-
ing, coating, etching, and related operations. The constituents in this waste
include the basis material being finished, as well as the components in the
processing solutions. Baths used for anodizing, coating, and etching usually
contain metal salts, acids, bases, dissolved basis metals, complexing agents,
and other deposition control agents. Bath constituents for chemical removal
of basis metals include mineral acids, acid chlorides, alkaline ammonium
solutions, nitro-organic compounds, and such compounds as ammonium peroxysul-
fate.
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 2-7 is a compilation of the various pollutants found in each subsegment
of the 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 (U.S. Department of Interior, 1980).
Hallowell et. al (1976) identified four waste streams as being destined for
land disposal. They include 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
17
-------
TABLE 2-6. TYPICAL PLATING SOLUTIONS9
Basis material
Plating Solution
Copper
Plain cyanide
Rochelle cyanide
Copper sulfate
Copper fluoborate
Nickel
Sulfamate
Fluoborate
Chloride
Cadmium
Cyanide
Fluoborate
Tin
Sulfate
Fluoborate
Halide
Gold
Cyanide
Acid
Iron
Chloride
Sulfate/chloride
Fluoborate
Chromium
Zinc
Chromic/sulfuric acid
Cyanide
Pyrophosphate
Lead
Fluoborate
a U. S. Department of Interior, 1980.
18
-------
TABLE 2-7. CHARACTERIZATION OF WASTE STREAM FROM ELECTROPLATING INDUSTRY9
Subpart - Concentrations (mg/L)
Pollutant
parameter
Copper
Nickel
Chromi urn,
total
Chromium,
hexavalent
Zinc
Cyanide,
total
Cyanide,
amenable
Fluoride
Cadmium
Lead
Iron
Tin
i tii
Phosphorus
Total suspended
solids
Silver
Gold
Palladium
Platinum
Rhodiumb
Common metals
plating
0.032-272.5
0.019-2,954
0.088-525.9
0.0005-534.5
0.112-252.0
0.005-150.0
0.003-130.0
0. 022-141. 7
0.007-21.60
0.663-25.39
0.410-1,482
0.060-103.4
0.020-144.0
0-10,000
Precious
metals
plating
0.005-9.970
0.003-8.420
0.020-144.0
0-10,000
0.050-176.4
0.013-24.89
0.038-2.207
0.112-6.457
0.034
Electroless
plating Anodizing
0.002-47.90
0.028-46.80
0.268-79.20
0.005-5.000
0.005-12.00 0.005-78.00
0.005-1.00 0.004-67.56
0.110-18.00
0.030-109.0 0.176-33.0
0-40 36-924.0
Coatings
0.190-79.20
0.005-5.000
0.138-200.0
0.005-126.0
0.004-67.56
0.410-168.0
0.102-6.569
0.060-53.30
20-5,300
Chemical
milling and
etching
0.206-272.5
0.088-525.9
0.005-334.5
0.112-200.0
0.005-126.0
0.005-101.3
0.022-141.7
0.075-263.0
0.068-103.4
0.060-144.0
0-4,300
a U. S. Department of Interior, 1980.
b Only 1 plant had a measurable level of this pollutant.
-------
could be generated in 1975, 1977, and 1983. These data are presented in
Table 2-8.
TABLE 2-8. HAZARDOUS WASTES DESTINED FOR LAND DISPOSAL
FROM THE ELECTROPLATING AND METALS FINISHING INDUSTRY
(JOB SHOPS) - DATA IN METRIC TONS ON A DRY BASIS
Type of waste
Water pollution control
sludges3
Process wastes
Degreaser sludges
1975
19,740
42,141
5,434
1977
56,399
42,141
5,434
1983
73,882
55,206
7,118
Electroless nickel
wastes 11,422 11,422 15,063
Total 78,737 115.396 151.269
a From Hallowell et al., 1976.
b Total hazardous constituents in water pollution
control sludges: 1975, 8,016; 1977, 22,913; 1983,
29,903.
The data in the table include only estimates for the job shops. The captive
shops of this industry, which are parts of larger manufacturing companies,
would make the total amount of wastes for this industry considerably larger.
The principal hazardous constituents in these wastes are the heavy metals and
residual organic material. From the standpoint of the effects upon the
liners, the heavy metal ions and the other inorganic constituents can be
expected to affect particularly the soil type liner materials, and the re-
sidual organics that are in these wastes, including polychlorinated materials,
could affect a variety of the membrane and organic type liner materials.
2.3.7 Petroleum Refining Industry
The petroleum refining industries produce very different waste streams from
the various refining processes. Highly caustic sludges result from operations
including washing, sweetening, and neutralizing. Spent caustic solutions are
discharged from alkylation, isomerization units, and LPG treating processes.
The waste stream is roughly 3-3.5% NaOH by weight. Oily refinery sludges
contain sand, silt, heavy metals, and an array of organic compounds in addi-
tion to oil and water. The oil content of such wastes ranges from 1-82% by
weight. Refer to Table 2-9 for concentrations and quantities of several
wastes resulting from refining processes.
20
-------
no
TABLE 2-9. RANGES OF CONCENTRATIONS AND TOTAL QUANTITIES FOR REFINERY SOLID WASTE SOURCES3
(All values in milligram per kilogram except where noted)
Parameters
Phenols
Cyanide
Selenium (Se)
Arsenic (As)
Mercury (Hg)
Beryllium (Be)
Vanadium (V)
Chromium (Cr)
Cobalt (Co)
Nickel (Ni)
Copper (Cu)
Zinc (Zn)
Silver (Ag)
Cadmium (I'd)
Lead (Fb)
Molybdenum (Mo)
Ammonium
Salts (as NH4+)
Benz-a-pyrene
Oil (wt.Z)
Total Weight
Metric Tons/yr.
Sludge from
Clarified Once
Through Cooling
Water
0.0-2.1
0.01-0.74
0.1-1.7
0.1-18
0.42-1.34
0.013-0.63
15-57
16.6-103
5.3-11.2
20.5-39
56-180
93-233
0.84-1.3
0-1.0
17.2-138
0.5-33.
0.01-13
0-1.8
0.24-17.0
9.7-18.0
Exchange
Bundle
Clearing
Sludge
8-18.5
0.0004-3.3
2.4-52
10.2-11
0.14-3.6
0.05-0.34
0.7-50
310-311
0.2-30
61-170
67-75
91-297
Trace
1.0-1.5
0.5-155
1.0-12
5-11
0.7-3.6
8-13
0.4-1.0
Slop Oil
Emulsion
Solids
5.7-68
0-4.6
0.1-6.7
2.5-23.5
0-12.2
0-0.5
0.12-75
0.1-1325
0.1-82.5
2.5-288
8.5-111.5
60-656
0-20.1
0.025-0.19
0.25-380
0.25-30
0-44
0-0.01
23-62
1.4-29.2
Cool ing
Tower
Sludse
0.6-7.0
0-14
0-2.4
0.7-21
0-0.1
Trace
0.12-42
181-1750
0.38-7
0.25-50
49-363
118-1,100
0.01-1.6
0.06-0.6
1.2-89
0.25-2.5
0.07-14
0-0.8
0.07-4.C
0.1-0.13
API/Primary
Clarifier-
Separator
Bottom
3.8-156.7
0-43.8
0-7.6
0.1-32
0.04-7.2
0-0.43
0.5-48.5
0.1-6790
0.1-26.2
0.25-150.4
2.5-550
25-6,596
0.05-3
0.024-2.0
0.25-83
0.25-60
0.05-24
0-3.7
3.0-51.3
0.1-45
Dissolved Air
Flotation
Float
3.0-210
0.01-1.1
0.1-4.2
0.1-10.5
0.07-0.89
0-0.25
0.05-0.1
2.8-260
0.13-85.2
0.025-15
0.05-21.3
10-1,825
0-2.8
O-rO.5
2.3-1,320
0.025-2.5
8.7-52
0-1.75
2.4-16.9
13.6-31.0
Kerosene
Filter Clays'
2.0-25.2
Trace
0.01-26.1
0.09-14
0-0.05
0.025-0.35
13.2-42
0.9-25/8
0.4-2.3
0.025-15
0.4-12,328
6.6-35
0.02-0.7
0.19-0.4
4.25-12
0.012-8.8
•UK01
1.7-1.8
0.7-5.6
0.79-127
Lube Oil
Filter Clays
0.05-6.4
0.01-0.22
0.1-2.1
0.05-1.4
0.04-0.33
0.025-0.5
0.5-65
1.3-45
1.3-5
0.25-22
0.5-8.0
0.5-115
0.013-1.0
0.025-1.5
0.25-2.3
0.025-0.05
2-4
0.02-0.2
•v3.9
102-682
Waste
Biosludge
1.7-10.2
0-19.5
0.01-5.4
1.0-0.6
0-1.28
Trace
0.12-5
0.05-475
0.05-1.4
0.013-11.3
1.5-11.5
3.3-225
0.1-0.5
1.16-0.54
1.2-17
0.25-2.5
28-30
Trace
0.01-0.53
1.8-38.5
continued -
-------
TABLE 2-9 (continued)
rv>
ro
Parameters
Phenols
Cyanide
Selenium (Se)
Arsenic (As)
Mercury (Hg)
Beryllium (Be)
Vandium (V)
Chromium (Cr)
Cobalt (Co)
Nickel (Ki)
Copper (Cu)
Zinc (Zn)
Silver (Ag)
Cadmium (Cd)
Lead (Pb)
Kolybdenun. (Mo)
Ammonium
Salts (as NH4+)
Benz-a-pyrene
Oil (wt.Z)
Total Weight
Metric Tons
Coke
Fines
0.4-2.7
Trace
0.01-1.6
0.2-10.8
O-d.2
0-0.2
400-3,500
0.02-7.5
0.2-9.2
350-2,200
3.5-5.0
0.2-20
0.01-3.0
0.015-2
0.5-29
0.1-2.5
No value
Trace
0-1.3
0.06-4.2
Silt from
Storm Water
Run off
6.3-13.3
0.48-0.95
1.1-2.2
1.0-10
0.23-0.36
Trace
25-112
32.5-644
11.0-11.3
30-129
14.8-41.8
60-396
0.4-0.6
0.1-0.4
20.5-86
6.3-7.5
1.0
0.03-2.5
2.2-5.5
2.7
Leaded
Tank
Bottoms
2.1-250
Trace
0.1-3.1
63-455
0.11-0.94
Trace
1.0-9.8
9.0-13.7
26.5-71
235-392
110-172
1190-17,000
0.05-1.7
4.5-8.1
158-1,100
0.5-118
No value
0.02-0.4
18.9-21
0.2-1.3
Non-Leaded
Product Tank
Bottoms
1.7-1.8
0-14.7
1.5-22.4
Trace
0.41-0.04
0.025-0.49
9.1-34.6
12.7-13.1
5.9-8.2
12.4-41
6.2-164
29.7-541
0.5-0.7
0.25-0.4
12.1-37.3
0.25-18.2
0.2
0.3-0.9
45.1-83.2
34.7-77
Neutralized HF
Alkylation
Sludge (CaF,)
3.2-15.4
0.21-4.6
0.1-1.7
0.05-4.5
0.05-0.09
0.012-0.13
0.25-5
0.75-5
0.-3-0.7
7.4-103
2.5-26
7.5-8.6
0.12-0.25
0.012-0.12
4.5-9.6
Trace
Trace
No value
6.7-7.1
28-67
Crude
Tank
Bottoms
6.1-37.8
0.01-0.04
5.8-53
5.8-53
0.07-1.53
Trace
0.5-62
1.9-75
3.8-37
12.8-125
18.5-194
22.8-425
0.03-1.3
0.025-0.42
10.5-258
0.025-95
2.0
0-0.6
21-83.6
0.14-0.26
Spent Line
from Boiler
Feedwater
0.05-3.6
0-1.28
0.01-9.2
0.05-2.3
0-0.5
Trace
0-31.6
0.025-27.9
0-1.3
0.13-26.2
0.22-63.2
2.0-70
0.05-0.7
0-1.3
0.01-7.3
0-0.05
Trace
Trace
0.04-0.5
28.5-214.7
Fluid Catalytic
Cracker Catalyst
Fi nuc
0.3-10.5
0.01-1./.4
0.01-1.4
0.05-4.C
0-0. 16
0.025-].,
74.4-l.-2i
12.3-19'-
0.25-37
47.5-95C
4.1-336
19-170
0.5-3.0
0-0.5
10-274
0.5-71 '
No value'
0-1.0
0.01-0.8
0.65-23.6
*From Stewart, 1978.
-------
The oils, organics, high pH, and high ion concentrations may all be harmful to
landfill or disposal site liners. Compatibility studies should be made before
installing liners for this class of waste (Landreth, 1978).
2.3.8 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:
pH Chromium
Color Copper
Turbidity Lead
Alkalinity Zinc
Temperature Iron
Nitrogenous compounds Cobalt
(organic, amines, and nitrates) Cadmium
Oils and greases Manganese
Dissolved solids Aluminum
(principally inorganic chemicals) Magnesium
Phosphates Molybdenum
Phenolic compounds Nickel
Sulfides Vanadium
Cyanides Antimony
Fluorides Numerous organic
Mercury chemicals
The major pollutants in the wastewater from the rubber products industry are
oil, grease, suspended solids, and extreme pH. The synthetic rubber industry
has a wastewater of high COD and BOD contents; heavy metals, cyanides, and
phenols are usually present in less than 0.1 mg/L concentrations (Riley,
1974). The oils, organics, and metal ions are all potentially damaging to
various lining materials (Landreth, 1978).
2.3.9 Pharmaceutical Industry
Wastes generated by the pharmaceutical industry include chemically and biolog-
ically 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 are usually landfilled. This contains biological
sludge from wastewater treatment, aluminum hydroxide, magnesium, and sodium
salts (McMahan et al., 1975).
The major waste producing processes are extraction and concentration, product-
by-product, and equipment washings. See Table 2-10 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.
Fermentation and chemical synthesis wastes resulting from this industry
frequently are a mixture of aqueous, organic, and inorganic constituents.
23
-------
ro
TABLE 2-10. RAW WASTE CONSTITUENTS FROM THE PHARMACEUTICAL INDUSTRY3
(g/kg Production)
Fermentation
Biological products and
nautral extractive man-
facturing
Chemical synthesis
Formulation
Research
IDS
5.990
895
1.060
11.3
1.33
N03-N
4.68
0.02
0.20
0.053
Trace
Total
P
22.0
7.3
7.83
0.15
0.23
Oil
and
grease
413
3.62
21.6
0.78
(b)
Cl
1.260
211
104
2.51
0.94
S04
274
277
203
0.52
1.27
Sulfide
(b)
(b)
0.007
(b)
Total
Hard-
ness
294
61.6
5.82
...
Ca
123
36.4
15.2
1.01
...
Mg
30
5.68
. . .
...
Cu
0.005
0.12
0.002
0.001
...
Phenol
0.15
0.073
0.16
...
aRiley, 1974.
Data not reported.
-------
Thus, waste-liner compatibility studies are essential before lining a disposal
site for this complex type of waste.
2.4 Other Nonradioactive and Special Wastes
Wastes from power plants are usually ashes, air-pollution control equipment
sludges, cooling tower blowdown and boiler and metal cleaning wastes. The
wastes tend to have extreme pH's and contain large amounts of calcium sulfate,
sulfites, carbonates, and metals. Metals are usually at trace levels, but the
allowed limits for domestic water supplies are often exceeded by some metals
(Styron and Fry, 1979). Table 2-11 presents the metal contents of several
wastes. While the toxicity of this waste is relatively low, the tremendous
quantities of ash and sludges produced present a major solid waste disposal
problem. Fly ash has been used for a number of years as a road base mater-
ial. It can be mixed with lime and water to produce a cement-like material or
mixed with cement itself. However, the supply currently far exceeds the
demand for this type of material (Santhanam et al., 1979).
Mining wastes, tailings, and water drainage present pollution problems of high
acidity, high dissolved and suspended solids and high metal concentrations.
The tailings often contain a large amount of sand and fine material which is
carried by water, creating a pollution problem. Tailings from toxic metal
ores must be disposed of in a site specifically designed and maintained to
properly handle such wastes.
2.5 Discussion of Waste Fluids
The durability and service life of a given liner depends to a great extent
upon the specific fluids with which it is in contact from the time it is
originally placed. It must be recognized that, in almost all disposal
impoundments, the waste and the waste fluids are continually changing in
composition with time. Consequently, an important consideration in the
operation of a disposal site is that measures be taken to minimize the
variation in the character of the waste, as there is no single lining material
which can resist all wastes.
Liners can vary greatly in chemical composition from compacted soils and clays
to highly crystalline polymeric materials which are highly chemically resis-
tant and have very low permeability. Similarly the wastes, as indicated in
the above discussion in this chapter, can vary from highly polar solvents,
like water, through highly nonpolar materials, like lubricating oils and
hydrocarbon solvents. Most of the wastes will probably contain water as a
principal carrier. All materials have, to a certain degree, a solubility in
water; consequently, contaminants 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 many of the liners.
Furthermore, even minor amounts of the organic materials in the water or
leachate can preferentially combine with organic liner materials, e.g. asphalt
or all of the polymeric materials.
Dissolved organic constituents, even in minor amounts, will gradually dissolve
in the organic liners and, over extended periods of time, may cause the
25
-------
TABLE 2-11. TRACE ELEMENT CONTENT3 OF SAMPLES FROM COAL FIRED
ELECTRIC POWER GENERATING STATIONb
Element
Antimony
Arsenic
Barium
Beryllium
Boron
Cadmium
Chromium
Copper
Fluorine
Germanium
Lead
Manganese
Mercury
Molybdenum
Nickel
Selenium
Vanadium
Zinc
Coal
(ppm)
.33
4.6
100
.16
96.9
7.9
.45
41.5
372
4.5
41
142
.322
.41
51.7
3.2
<12
780
Bottom
ash
(ppm)
3.4
3.9
300
4.5
53.8
1.6
5.5
130
95.7
.25
21
491
<.010
1.4
187
.51
<24
798
Lime-
stone
(ppm)
3.2
2.7
<30
.17
17.4
.65
<.80
2.4
117
.11
13
290
.020
12
6.20
.22
<160
48
Waste
(ppm)
6.7
6.7
<20
1.8
41.8
25
5.2
65
266
5.9
290
340
0.10
9.6
75.2
2.1
<100
2050
Ash pond
liquor
(mg/L)
.03
.004
<.3
.001
1.03
.04
<.0002
.01
10.4
.07
.008
1.1
.0015
.10
11
.015
.2
2.5
Scrubber
liquor
(mg/L)
.06
<.0004
<.3
.004
6.17
.009
<.0002
.01
15.9
.39
.010
2.0
.002
.27
.25
.18
.2
4.2
Makeup
water
(mg/L)
.005
.002
<.3
.001
.414
.0007
<.0002
.006
.66
.02
.014
.15
<.001
.02
<.0l
.0012
.2
.04
a Values represent the average of duplicate determinations. Solid samples
are reported on a dry basis; water and liquor samples on an as-sampled
basis.
b Santhanam et al., Vol. 3, 1979.
26
-------
failure of a liner based upon organic materials. There are indications that
organic waste liquids can also have major adverse effects on some soils and
clays.
The character of wastes and their effects on liners are discussed further in
Chapter 4.
27
-------
REFERENCES
Chapter 2 - Description of Wastes and Identification of Pollutants
Becker, D. L. 1974. Development Document for Proposed Effluent Limitations
Guidelines and New Source Performance Standards for the Synthetic
Resins Segment of the Plastics and Synthetic Materials Manufacturing
Point Source Category. EPA-440/l-74/010a. U. S. Environmental Protec-
tion Agency, Washington, D. C. 247 pp. PB 239-241/BBA.
Becker, D. L. 1975. Development Document for Effluent Limitations Guide-
lines and Standards for the Synthetic Polymer Segment of the Plastics
and Synthetic Materials Point Source Category. EPA-440/l-75-036b. U. S.
Environmental Protection Agency, Washington, D. C. 302 pp. PB 240-862/3BA.
Breland, C. G. 1972. Landfill Stabilization with Leachate Recirculation,
Neutralization, and Sludge Seeding. Georgia Institute of Technology,
School of Civil Engineering. 80 pp.
Brunner, D. R., and R. A. Carnes. 1974. Characteristics of Percolate of
Solid and Hazardous Wastes Deposits. Presented at AWWA (American Water
Works Association) 4th Annual Conference. Boston, MA. 23 pp.
Cheremisonoff, N., P. Cheremisonoff, F. Ellerbusch, and A. Perna. 1979.
Industrial and Hazardous Wastes Impoundment. Ann Arbor Science Publish-
ers, Inc., Ann Arbor, Michigan, pp. 192-208.
De Vera, E. R., B. Simmons, R. D. Stephens, and D. Storm. Samplers and
Sampling Procedure for Hazardous Waste Streams. EPA 600/2-80-018.
U. S. Environmental Protection Agency, Cincinnati, Ohio. 70 pp. PB 80-135353'
EPA-OSWMP. 1973. An Environmental Assessment of Potential Gas and Leachate
Problems at Land Disposal Sites. (Open-file report, restricted distribu-
tion.) U. S. Environmental Protection Agency, Washington, D. C.
EPA-OSWMP. 1974. Report to Congress - Disposal of Hazardous Wastes. SW-115.
U. S. Environmental Protection Agency, Washington, D. C. 110 pp.
EPA-OSWMP. 1975. Use of the Water Balance Method for Predicting Leachate
Generated From Solid Waste Disposal Sites. SW-168. U. S. Environmental
Protection Agency, Washington, D. C. 40 pp.
EPA. 1977. Procedures Manual for Groundwater Monitoring at Solid Waste
Disposal Facilities. EPA-530/SW-611. U. S. Environmental Protection
Agency, Cincinnati, Ohio. 269 pp.
EPA. 1980. Test Methods for Evaluating Solid Waste - Physical/Chemical
Methods. SW-846. U. S. Environmental Protection Agency, Washington,
D. C. PB 220-479.
28
-------
Genetelli, E. J., and J. Cirello, eds. 1976. Gas and Leachate from Land-
fills - Formation, Collection, and Treatment. EPA 600/9-76-004.
U.S. Environmental Protection Agency, Cincinnati, Ohio. 190 pp. PB 251-161
Gregg, R. T. 1974. Development Document for Effluent Limitations Guidelines
and New Source Performance Standards, - Soap and Detergent Manufacturing,
Point Source Category. EPA-440/l-74-018a. U. S. Environmental Pro-
tection Agency. Washington, D. C. 202 pp. PB 238-613/4BA.
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, Ohio. 146 pp. (PB-287-140).
Hallowell, J. B., L. E. Vaaler, J. A. Gruklis, and C. H. Layer. 1976.
Assessment of Industrial Hazardous Waste Practices - Electroplating and
Metal Finishing Industries - Job Shops. SW-136C. U. S. Environmental
Protection Agency, Washington, D. C. 190 pp. (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, Donald E.
McFaddin, and E. J. Daley. 1979. Recovery, Processing, and Utilization
of Gas from Sanitary Landfills. EPA-600/2-79-001. U. S. Environmental
Protection Agency, Cincinnati, Ohio. 133 pp. PB 293-165.
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, Ohio. 53 pp. (PB-259-913).
Landreth, Robert. 1978. Research on Impoundment Materials. Presented at
the First Annual Conference of Advanced Pollution Control for the Metal
Finishing Industry. EPA-600/8-78-010. U. S. Environmental Protection
Agency. Cincinnati, Ohio. 143 pp. PB 282-443/1BE.
McMahan, J. N., L. Cunningham, L. Woodland, and D. Lambros. 1975. Hazardous
Waste Generation, Treatment and Disposal in the Pharmaceutical Industry.
Contract No. 68-01-2684. U. S. Environmental Protection Agency, Washing-
ton, D. C. 178 pp.
Phillips, N. P., and R. Murray Wells. 1974. Solid Waste Disposal. Final
Report. EPA-650/2-74-033. U. S. Environmental Protection Agency, Wash-
ington, D. C. 268 pp. PB 233-144/5BA.
Riley, J. E. 1974. Development Document for Effluent Limitations Guide-
lines and New Source Performance Standards for the Tire and Synthetic
Segment of the Rubber Processing Point Source Category. EPA-440/1-
74/Ol3a. U. S. Environmental Protection Agency, Washington, 0. C. 195
pp. (PB-238-609).
29
-------
Santhanam, C. J., R. Lunt, C. Cooper, D. Kleinschmidt, I. Bodek, and W.
Tucker. 1979. Assessment of Technology for Control of Waste and Water
Pollution from Combustion Sources. First Annual R & D Report, Volume 3.
Generation and Characterization of FGC Waste. U. S. Environmental
Protection Agency, Research Triangle Park, NC.
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,
Ohio. 76 pp. PB 291-881.
Styron, C. R. Ill, and Z. B. Fry. 1979. Flue Gas Cleaning Sludge Leachate/
Liner Compatibility Investigation - Interim report. EPA-600/2-79-136.
U. S. Environmental Protection Agency, Cincinnati, Ohio. 78 pp. PB 80-100481
U. S. Department of Interior. 1980. Evaluation of the Application of Desal-
ination Technology for Treatment of Wastewaters for Reuse. Unpublished.
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, D. C. 296 pp.
Wigh, R. J. 1979. Boone County Field Site. Interim Report, Test Cells 2A,
2B, 2C, and 2D. EPA-600/2-79-058. U. S. Environmental Protection
Agency, Cincinnati, Ohio. 202 pp. (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, Ohio. 225 pp. PB 284-716/8BE.
30
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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 the potentially
polluting constituents of the waste from leaving the site and entering the
groundwater or surface water system in the proximity of the site. The pollut-
ants, as discussed in Chapter 2, include organic and inorganic materials,
solids, liquids, gases, and bacteriological species. In their performance
liners function by two mechanisms:
a. To impede the flow (flux) of the pollutant and pollutant carrier,
usually water, into the subsoil and thence into the groundwater.
This requires a construction material having low permeability.
b. To absorb or attenuate suspended or dissolved pollutants, whether
organic or inorganic, in order to reduce the 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 both mechanisms but to different degrees
depending on the type of liner material and the waste fluid and constituent.
Membrane liners are the most impermeable of the liner materials, but have
little capacity to absorb materials from the waste. They can absorb a rela-
tively small amount of organic material but, due to their small mass, their
total absorption is small. Soils can have a large capacity to absorb mater-
ials of different types, but they are considerably more permeable than a
polymeric membrane. However, the greater thickness of the soil can result in
low 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
Manual. In this chapter, the major candidates for use as liner materials
are discussed.
For the purpose of this manual, we consider a liner to be a material con-
structed or fabricated by man. Such a definition includes soils and clays
having low permeability which are (1) either brought to a site or available
on the site and (2) compacted or remolded to reduce permeability and increase
strength.
Liners can be classified in a variety of ways, such as construction method,
physical properties, permeabiliity, composition, and type of service. These
classifications are presented in more detail in Table 3-1. In this chapter,
the various types of liners are discussed in the following classes:
31
-------
- Soil and clays
- Admixes
- Polymeric membranes
- Sprayed-on liners
- Soil sealants
- Chemisorptive liners.
For each type of lining material, characteristics and general features of the
liner and the advantages and disadvantages are discussed.
TABLE 3-1. CLASSIFICATION OF LINERS FOR WASTE DISPOSAL FACILITIES
A. BY CONSTRUCTION:
- Onsite construction:
- 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
- Semirigid
- 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.
32
-------
3.2 Soils and Clay
3.2.1 Introduction
Due to their general availability, clayey soils should be considered the first
alternative for a waste confinement liner. Based on engineering, environ-
mental, 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 dis-
posal site and which has been properly treated, remolded and/or compacted so
that a flow-imped ing layer of low permeability to wastes has been obtained.
The compacted soil liner has to be designed following a proper environmental
analysis. Criteria have to be set 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 require-
ments, failure should not occur.
3.2.2 Fundamental Properties of Soils
3.2.2.1 Chemistry and Mineralogy of Soils and Clays
Soils to be used as liners at waste disposal facilities must contain a rela-
tively large proportion of fines, i.e. particle size less than 2 ym. For a
broad range of soils a close correlation between soil permeability and clay
(less than 2 urn ) content has been observed; soils exhibiting low permea-
bility generally contain a large proportion of fines. The minimum amount of
clay size particles required in soil to yield a good soil liner is 25-28%
by weight.
The distinction between clay and nonclay made at particle size equal to 2 ym
is based on the observation that clay minerals are heavily concentrated below
this size, while nonclay minerals constitute the bulk of soil solid phases
above this particle size.
This general rule deserves a more careful consideration. When examining
particular clay minerals, one finds that typically each clay mineral has a
preferred particle size distribution in the range less than 2 ym; since the
colloidal character of a particle increases with the decrease in size, differ-
ent clay minerals will have different degrees of colloidality. Also of
significance is the real colloidal range, considered to be from 1 nm to 1 ym
(Daniels and Alberty, 1963, p.573). Due to the relatively large surface area
of the clay size fraction in a clayey soil, the mechanical behavior of such a
soil is dependent on the surface physico-chemical characteristics; and since
these are determined by the clay mineral chemistry, the bulk behavior of a
clayey soil can be understood only if the chemistry and the mineralogy of the
clay fraction are carefully considered.
33
-------
Of importance in the clayey soil functioning as a liner are the changes in
interlayer spacing and the consequent volume changes exhibited by different
clay minerals when exposed to organic or inorganic chemicals that are likely
to appear in a waste impoundment fluid. Table 3-2 presents some of the
essential features of kaolinite, illite, and montmorillonite, the three clay
mineral species most likely to constitute the bulk of the clay fraction of
many soils. These three species are discussed briefly below.
TABLE 3-2. TYPICAL VALUES FOR PROPERTIES OF KAOLINITE, ILLITE,
AND MONTOMORILLONITE9
Particle thickness
Clay mineral
Kaolinite
Con-
tracted
(run)
200.0
Hydra-
tedb
(nm)
202.0
Volume
change,
%
1
Charge0
per
formula
weight
0
Surface
area,
m2/g
8
Exchange
capacity
meq/lOOg
Cation Anion
10 pH
(nonexpansive
1:1 lattice)
II lite
(nonexpansive
2:1 lattice)
Montmorillonite
(expansive
2:1 lattice)
dependent
20.0 22.0 10 1.0 80 15 pH
dependent
2.0 6.0 200 0.5 800 100 pH
dependent
<5
a Brown and Anderson, 1980, p 124.
b Four water layers absorbed for each available basal surface.
c Units are multiples of electrostatic units (esu). One charge = 4.8029 x 10~7
esu.
Kaolinite particles have a small negative surface charge. Adjacent layers of
this mineral are strongly held together by hydrogen bonding. For this reason
kaolinite exhibits little interlayer expansion; adsorption can occur only on
external particle surfaces. Edges of the crystal exhibit broken bonds which
give rise to a small number of highly pH-dependent positive or negative
charges.
Illite is characterized by the presence of "fixed" potassium ions in a twelve-
fold coordination between two planes of oxygen atoms. The high 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; con-
sequently 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 only a fraction of the
potential one. The real CEC of the illite is consequently intermediate
between the CEC of kaolinite and that of montmorillonite.
34
-------
Montmorillonite has characteristically the smallest particle size of the three
clay minerals. Typically the site of the negative charge is in the inner
octahedral layer in which incomplete isomorphous substitution occurs; this
generates a minimal cohesion between successive 2:1 layers, resulting in a
very receptive and chemically active structure. Montmorillonite 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 displac-
ed by other fluids that yield a lower interlayer spacing.
Permeability of the 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 montmorillonite.
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). This
increase corresponds to a 1 nm thickness of water per surface when Ca-mont-
morillonite is fully expanded. With divalent cations such as calcium or
magnesium adsorbed to its surfaces, montmorillonite 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 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 permeabil-
ity, the expansion is reversible and hence sodium montmorillonite is suscept-
ible to shrinkage if it dries. Another problem with sodium-montmorillonite is
that when it is fully expanded, it is susceptible to dispersion and internal
erosion (see 4.3.3., "Piping"). A dispersed clay that lacks structural
strength could flow as a viscous fluid if it is free to expand. This condi-
tion may cause problems such as loss of strength in waste impoundment side
walls.
Quirk (1965) found the permeability of sodium saturated montmorillonite
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 decreases in the calcium concentration in 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 concentra-
tions in a fluid passing through a film of sodium saturated montmorillonite
suppressed the double layer. The diminished double layer effect inhibited
swelling while it decreased interlayer spacing and permeability.
35
-------
100
100
%Ca
Exchangeable Cation
Figure 3-1 Relative permeability values for three clays with variable per-
centages of calcium and sodium on exchange sites (Yonq and
Warkentin, 1975).
36
-------
3.2.2.2 Attenuation Properties of Soil Liners
A clayey soil liner below a potentially polluting waste can attentuate a
pollutant by reducing the level of contamination (if present), spreading the
contamination over a much longer period, and lowering considerably the maximum
value of contamination, i.e. highest discharge of contaminant per unit area
and time during the period of operation. The term "attenuation" at the same
time implies that a soil liner cannot be an "absolute" liner. This point is
illustrated schemetically by Figures 3-2 and 3-3 for which the following
assumptions were made:
- The rate of contamination is defined as the amount of polluting
species passing through a unit area per unit time, e.g. grams per
square meter per day.
- The rate of contamination is evaluated in all cases at a depth L from
the waste interface. The depth L is also taken as the thickness of
the liners in cases B through E, inclusive.
- The permeability of the liners in Cases B through E, inclusive, is
assumed to be the same.
- The permeability of the native soil is assumed to be greater than that
of the clayey soil liners.
- The absorptive capacity for the polluting species in Case C is less
than the corresponding capacity in Case D.
- The absorptive capacity of the liner in Case E is greater than the
total mass loading of polluting species of the single load situation.
- The single unit load situation is defined as a set, finite amount of
polluting species at a given hydraulic gradient which, over time, will
approach zero as the polluting species passes through the soil and/or
liner and is not replenished.
- The constant, continuous waste loading is defined as the maintenance
of a given constant concentration of polluting species at a given
hydraulic gradient over time. This implies replenishment of the
polluting species in the waste.
- The analysis assumes saturated flow.
- The analysis assumes that the waste does not damage the liner or its
structural integrity.
Shown in Figure 3-3 are rate curves for the two loading conditions defined
above. Analysis of Figure 3-3 reveals that Case A, as expected, has the
highest flux of pollutant contamination, reached within the shortest relative
time period. In the situation of single unit loading a plateau is reached,
continues for a period of time and then drops off as the amount of pollutant
37
-------
s~*
-v.
WASTE
j ~
1
r
NO LINER
^ ~" r
x— N
^ ( *~
• • \* '!'."•'.'• ••••'*'.'• i'
•ji/NAfivE;1;;:
:; :.*•'••'•;•••.'•;'.•.'• ;'•;•
%&v)::^:::"
A
X
WASTE -
( 1
/ \ "
LINER
NO
ABSORPTION
'.'•''.'•'•'.' ' '•'• '.•'.'•'
':;;-. NATIVEV.-V
•'; '• •••';'• -: :•'."•••'•'.'
'•".'•'"'. '•".•'.*••'•'•'.'•'•"
B
^ /
' WASTE
; / ' -
/ •v- ~>-
LINER
SOME
ABSORPTION
'•&:&&'-;'-
;'.;: NATIVE:';'^
•|'.:V: SOIL ;'•;;;•'
•'•';.'•:.".."•"/•.';'.•.'.'/.
<-:/:U^:-:;:::'.'S
c
^ f
s*
i
WASTE
—' /
^^;
LINER ,
/ > r <
LARGER
ABSORPTION
^/£;.V^ :\:
;.y;NATIV ••
/:';';•': SOIL '••;};
'• •"•'•'•';'. '.*•'' *•' •
D
-^ /"
s
WASTE
-~
v __
LINER
LARGEST
ABSORPTION
'.': .'•.'•>'-':'-'r •••"•.'
'••;NAfivE;:.;'
;•:';• SOIL. •;';'.
'•/.••X::;:.'::.;:;.:i
ifflSi§SS
E
Figure 3-2. Attenuation of polluting species by soil liners of diff
absorptive capacities. Schematic representation of each liner
situation under consideration.
TIME
Figure 3-3. The rates of contamination of soil liners from Figure 3.2 at the
depths equal to the thickness of the liners.
38
-------
remaining decreases. In the situation of constant, continuous loading, the
plateau is maintained due to the steady loading condition. In Case B, a liner
is present which functions solely to impede flow by reduced permeability.
The distinction between A and B is one of intensity of contamination; the
capacity of contamination is the same since the integrals below the two curves
for times between 0 and t are assumed to be equal. The factors controlling
the degree of contamination are mainly physical (flow properties) inasmuch as
absorption is assumed not to affect them drastically. In drawing these two
curves, one assumes that the contaminant concentration of any polluting
species follows the same pattern; the flat plateau represents the situation of
the maximal concentration controlled by the characteristic dissolution/precip-
itation reactions of the effluent. All in all, the permeability differential
has the effect of diminishing the intensity factor but leaving the capacity of
contamination unaltered, only a retardation effect is accomplished.
In examining Cases C and D, it can be seen that reaching the maximum rate of
contamination is delayed due to the absorptive capacity of the liners. At any
time prior to attaining the maximum rate plateau the difference in the rate
curves reflects the magnitude of absorptive capacity of each liner. This
absorptive capacity can be defined as the altering of the chemical composition
of the waste fluid with respect to the polluting species such that the species
is irreversibly retained in the liner. Characteristic curves like C and D
will be generated depending on the degree of retention of the polluting
species by the liner. If the relationship between a particular contaminant
and the liner is so large that the pollutant is almost totally retained, then
no plateau will exist for such a curve for single loading and a situation
similar to that described for Case E will result. The characteristic curve
shown by Case E reflects "leakage" in the system. In the situation where
constant, continuous loading is applied, the characteristic curve for Case E
after a relatively long period will approach the plateau level of Cases B, C,
and D.
Further analysis of Figure 3-3 shows the rate differential of the character-
istic curve plateaus for the constant, continuous loading situation. This
differential, given the assumptions stated previously, is mostly a function of
permeability of the soil versus the liner.
Attenuation and cation exchange capacity -
The term "attenuation" is sometimes erroneously linked to metallic trace
elements through the well-known cation exchange properties of soils; this
connection can be grossly misleading on at least two bases:
a. Soil cation exchange properties are revealed by true exchange
reactions. A cation can be adsorbed and temporarily stored into
the liquid-solid interface; upon the decrease of concentration in
the liquid phase, it will be again released. Consequently, if an
exchange would have been present in Soil B, then the degree of
contamination versus time relationship should have been a mirror
39
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image of Curve B, but slightly displaced to the right on the time
scale. The picture described by Soil C does not correspond to such
a situation. Curve C describes the situation in which the retention
of the cation was permanent. Although these reactions are known in
soil chemistry (for metallic species like K, Li, etc.), the engineer
designing a waste disposal site should not rely on them.
b. For the same ionic composition and strength of waste effluent and
the same activity of a particular cation, the larger the cation
exchange capacity of a soil, the larger the amount of the element
temporarily stored. However, this amount is so dependent on the
chemistry of the effluent (its purity with regard to the particular
element considered, ionic composition, strength, secondary mineral
formation (precipitation/dissolution), the presence of chelating
agents, complex formation with different than assumed ionic forms,
etc.) that the effect of the magnitude of the exchange capacity is
almost totally offset.
Modeling the functionality of complex systems has been done (Lowell, 1975).
Such an analysis will require an accurate assessment of the interaction
between the particular waste and soil considered. This analysis can be only
obtained by setting up and performing a research program on the matter.
3.2.3 Engineering Characteristics of Soils and Clays
3.2.3.1 Atterberg Limits
Although empirical, the Atterberg limits are a powerful tool in assessing, as
a first approximation, the mechanical behavior of a clayey soil. 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 differs with moisture content. Clayey soils,
which are the types of soil required for liners, represent the most vivid
example in this respect. The effect the degree of hydration of clayey soil
has on its compressive strength is well known. The plastic limit and the
liquid limit are tremendously valuable in engineering work for characterizing
and assesing soils. 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 (although
creep deformation can very easily occur) and just above which the soil flows
(it behaves like a suspension). At the liquid limit, soil behavior is a blend
of plastic deformation (tends to cease deformation upon stress removal) and
liquid flow (deforms freely after stress removal).
Though the plasticity test generates results in terms of mechanical behavior,
it can furnish considerable information because it is simultaneously a chemi-
cal and a physical test. It can furnish information regarding the reaction of
clay and water, a reaction which is determined largely by the chemical and
mineralogical properties of the clays in the soil.
40
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The "Atterberg Limits" is the test which will help classify the soil and,
consequently, will heavily weigh in the decision-making process: it will
answer the question whether the waste disposal site is covered by a soil which
can be improved in a soil liner. Soils which 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
versus 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 ym 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 Atterberg limits are the result of a reaction between the clay phase of a
soil and water. Consequently, the composition of both soil and the water has
an affect on the plastic behavior of the soil. To bypass the difficulty of
using fluid with unknown and always different composition, the ASTM methods
recommend the use of distilled water which standardizes the procedure, but by
so doing the methods alter the magnitude of the plastic effect. In most
engineering work this procedure may not lead to significant errors. However,
a soil liner may be subjected during service to very aggressive liquids, in
many instances concentrated electrolyte solutions. Consequently, the use of a
moderately high electrolyte solution, such as 0.01 N CaS04 rather than
distilled water is recommended.
If the soil is suspected of being chemically sensitive (for instance a soil
containing more than 20%, by weight, montmorillonite clay), we recommend
performing Atterberg Limits by using both distilled water and 0.01 N CaSOa
on duplicate samples. Eventually, an actual waste liquor can be simulated ana
used as a molding fluid.
The power of this test lies in the fact that it is a simple, routine, and
relatively inexpensive test and, when using different fluids with different
compositions, valuable information can be gained regarding to the buffer
capacity of the soil, i.e. its ability to resist physico-chemical alterations
and perhaps mechanical changes.
3.2.3.2 Compactibility
The properties of a soil, particularly those of importance for a soil liner,
can be significantly altered by mechanical compaction. From the standpoint of
liners, the most important effect of compaction is upon the permeability of
the soil.
The fundamental aspects of soil compaction were established almost a half a
century ago by R. R. Proctor (Burmister, 1964). It is well known that
any soil has a unique laboratory density/moisture relation. I.e. Proctor
curve, if compaction conditions are held constant. The relationship defines
41
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a unique density value (maximum density) and a corresponding moisture content
(optimum moisture content) which are essential parameters for design consider-
ation.
Because construction equipment and methodology can be variable and complex,
standardizing uniquely the testing conditions will not necessarily generate
similar information for the field work. Thus, the modified AASHTO compaction
test procedure was introduced (McDowell, 1946). Based on this test a large
amount of information was collected on the effect of the field compactive
effort on the density-moisture content relationship.
In respect to this relationship, it is found that increasing the compactive
effort increases the maximum density and decreases the optimum moisture
content. Also quite well established is the effect of soil mechanical compo-
sition on the shape and position of the density-moisture content function:
a. The more granular the soil (the more sandy it is), the higher the
maximum density and 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 of the density as a func-
tion of moisture content.
Since the poorly defined peak on the density curve is a characteristic of
soils with more than 25-30% clay and since soils containing less than this
proportion of clay are tentatively excluded from construction of soil liners,
it becomes quite evident that:
a. The quality control for the density achieved in the field requires
considerably more attention and skill in the case of clayey soils.
b. The density obtained in the field should be only the first stage of
the field testing program; other tests must be conducted.
By superimposing the conclusions of the test results on general information,
the design should optimize the field compaction procedures to be used by the
construction contractor.
It is well known that any increase of compactive energy, any increase in
persistence of the applied energy, or any decrease of the layer thickness
results in a soil with a higher density. This constitutes basic information.
The test results have to quantify the interaction among these three factors.
The uniformity of moisture content of the undisturbed soil which is to be
compacted, is of major significance when light rather than heavy rollers are
being used. Heavy rollers seem to be more effective in compacting soil in a
field of variable moisture content (Burmister, 1964). On the other hand,
working the soil in the high moisture range with heavy rollers can result in
the development of positive pore-water pressures, an effect which seems to be
particularly true for highly plastic clayey soils (Porter, 1946). Under such
compaction the pore pressure which develops in the clay cannot dissipate
because of the low permeability of the clay. This aspect of the problem is
42
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important since, for reasons which will be discussed in Section 3.2.3.4, the
compaction operation in the field has to be conducted in the range of high
moisture content.
Compaction which results in generation of positive pressures and consequently
prevents densification is called "over compaction" (Turnbull, 1964; Holtz,
1964). To prevent its occurrence, or at least to minimize its dimension,
a compaction procedure called "stage compaction" is recommended (Burmister,
1964). According to Burmister, stage compaction is the "principle of matching
the supporting value and compactibility of soil layers by appropriate com-
pactive effort, weight, and efficiency of roller for two or more stages of
compaction in order to insure efficiency and effectiveness of compaction at
all stages". The principal reason for recommending stage compaction is that
stage compaction uses most of the compactive effort in densification rather
than shear deformation and thereby will increase the efficiency of that
effort. Indeed, when the strength of the compacted soil is the primary
concern, shear deformation is a wasted effort; but, in our case, lateral
displacement of the soil below the compacting implement is useful and is
discussed further in Section 3.2.3.4. Despite its limited use (since our
primary concern is flow impedance rather than strength), the designer should
consider stage compaction as a strategy in compacting the soil, because any
densification should yield a soil blanket with a lower permeability. In
compacting highly plastic clayey soils, the stage compaction may very well be
the only way to deal with this material. It has been also found that, in the
case of plastic soils, the thickness of the rolled layer should be decreased
(Porter, 1946).
In general, 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 increasing the number
of passes over the compacting layer. Some experimental results have also
shown that increasing the foot-pressures used and decreasing the layer thick-
ness in the same proportion result in equally dense soils (Sowers and Gul-
liver, 1955).
All this information is based on empirical considerations. Behavioral excep-
tions may be found and it is the role of the designer to identify and to use
them advantageously.
The design specifications must define the desired compaction in terms of
relative density or percent compaction and should be stated as "percentage of
the laboratory maximum density". This is particularly true in the case in
which the investigated area is covered by different soil types.
3.2.3.3 Volume Changes
Upon remolding and compaction a soil with a particular density can be obtain-
ed for which a set of relevant flow properties can be ascertained. Since a
certain fraction of the soil bulk volume will be filled with air at the end of
the compaction operation, the pore water pressure will be on the negative
side, i.e. water will be held under tension in soil. The presence of a soil
matrix will reduce the value of the water potential below the reference level
43
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(pore-water potential equal to 0). As indicated by Seed et al. (1962),
the basic factors controlling swelling in a soil that is not fully saturated
are those responsible for generating negative pore-water pressures. As a
general rule, all other factors being equal, the lower the pore pressure (the
larger the absolute value in the negative range), the more prominently mani-
fested is the swell of the soil.
The affinity of soils for water is expressed by the moisture characteristic
(moisture-retention water characteristic) curve in which the equilibrium
moisture retained at different suctions (negative pore-water pressures) is
measured. The measurement of negative pore-water pressures in samples freshly
compacted in the laboratory should provide the designer with valuable qualita-
tive information concerning the swell/shrink properties of the soil.
Since causes of negative pore-water pressures in unsaturated soils are ex-
plained in terms of soil-matrix intrinsic properties (if the pore fluid is at
a standard reference temperature and osmotic potential), the affinity of the
soil for water is measured and expressed as "matric potential".
Most often soil strength is defined as the sum of a cohesional component and a
frictional one, with the first component being viewed as relating to the soil
and the second one being ascertained only when normal loads are operative.
Similarly, one can look at positive pore-water pressures as those whose
manifestation depends on environmental conditions, while the matric potential,
similar to the cohesional strength, is a characteristic of the soil. Finally,
one should accept the point of view that there is a relationship between the
swell-behavior of soils and the resistance opposed by soils when compacted
(Meade, 1964).
For design considerations, volume changes are important because they occur
over time, after the placement of the soil liner. The design parameters
have to be established as a result of a careful consideration of swell behav-
ior and its influence on soil flow properties. Consequently, a prediction of
the swell pressure and swell potential of the soil has to be made. A detailed
development and analysis of swell behavior is presented in Appendix VI.
The effect of waste chemistry on volume changes and, consequently, on soil
flow properties is discussed in Section 4.2.2.3.
3.2.3.4 Permeability
Soil permeability, K, is a numerical measure of the ability of the soil to
transmit a fluid. When water is the permeating fluid through the soil, it is
often called hydraulic conductivity. K can be determined using Darcy's
relationship:
J = KAH
where J = volume of fluid passing through unit cross sectional area of soil
per unit time,
AH = hydraulic gradient, i.e. the rate of change of hydraulic head in the
direction of flow.
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When H is expressed as "weight hydraulic potential" (units of length, L) and J
as volume per area times time (units of LT~1), the permeability is expressed
in the c.g.s. system as cm sec'l.
Darcy's law is a useful relationship which has been widely used to determine
K. Its validity has been questioned for very dense clayey soils because the
fluid permeating the soil does not behave as a Newtonian liquid and the soil
does not preserve a rigid structure (due to osmotic and seepage forces).
Although the reputation of this relationship has been eroded, it still is the
main relation describing flow in a clayey soil; in qualitative terms it will
always be accepted, since, the larger the hydraulic gradient, the larger the
resulting flux.
Because K depends on properties of both components, soil and fluid, the term
"soil permeability" is not justified; to remove the effect of fluid proper-
ties, the notion of "intrinsic permeability coefficient" (IPC) is introduced;
thus:
where K1 = IPC expressed in the c.g.s. system as cm?
K = permeability (cm sec'l)
n1 = kinematic viscosity (cm^ s~l)
with n1 = —
p
n' = viscosity (g cm'l s~l)
p = density (g cm'3)
G = gravitational constant, 981 cm s"2 at 45° latitude.
It can be observed that the fluid viscosity normalizes the resistance to flow
due to the fluid cohesiveness, while the fluid density normalizes the effect
of gravity on fluid flow. In principle the use of IPC values permits the
comparison of K values of several soil samples of the same soil, when permeat-
ed by different fluids.
At G = 981 cm s'2, the relation between K and K1 for water at 25"C is express-
ed by the equation:
K' = 0.91 x 10~5 K
where K' is expressed in cm^ and K in cm s"l.
In the case of lined disposal sites, the soil liner may be contacted by fluids
with very exotic chemical compositions. In this case the kinematic viscosity
correction which is operated on K to produce K1 is a small improvement.
45
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The primary goal of constructing a blanket with low permeability is carried
out in the field by the compaction of soil. Through this operation a dense
soil material is obtained with a lower void ratio, since, according to both
Taylor-Poisseuille and Kozeny-Carman relationships (Lambe and Whitman, 1979),
K is proportional to e^ (l+e)~l where e is the void ratio.
All other factors being constant, a reduction in the void ratio should
result in a lower permeability, K. 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 decrease of the median pore size value. According to the
capillary model, the flux (LT~1) is proportional to the second power of the
radius.
A very important consequence of the K-e function is that soils being
particulate media and K being always measured on 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 have permeabilities in the range of 10"? cm s~l to
10~3 cm s~l. Intrinsic soil characteristics as well as naturally occuring
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~l to
ID'5 cm s-1.
However, if one tries to correlate K with the percentage of clay size part-
icles over that narrow range of permeabilities, the relation between particle
size and permeability becomes less significant; i.e. other factors become
relatively more significant in their effect upon flow properties. For one
thing, the types of clay minerals present in the clay fraction and, the
particle size distribution in the less than 2 ym fraction, play a very
important role. The interlayer chemistry of the crystal-unit, the suscepti-
bility of the particles to disperse or flocculate upon hydration and/or
mechanical remolding and the average size of a typical tactoid (agglomerate of
clay particles), all are factors which have a profound effect upon soil-water
flow characteristics; they can alter the K value by as much as two orders of
magnitude for otherwise apparently very similar soils. Since this can make the
difference between using or not using a particular soil as a liner, the
site-designing group has to obtain pertinent information regarding these
factors.
The physico-chemical behavior of a clayey soil has such an overwhelming effect
upon soil permeability because of the dependence of soil clay structure on
physico-chemical properties and the effect of the structure on permeability.
46
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If a soil clay fraction would have a fixed structure, totally insensitive to
changes in hydration conditions and stresses applied, then the K versus w
(water content) function would be a mirror change of the y density versus w
function with the lowest permeability corresponding to the maximum density, on
the Y vs. w graph. All of the physico-chemical factors mentioned have a
drastic effect on clays, particularly in the case of montmorillonite clays;
they have a very sensitive structure and the permeability of a montmorillonite
soil is far from being a simple function of density.
Lambe (1958) showed that the permeability of compacted clays is much greater
on the dry compared to the wet side of the optimum. He also concluded that
the higher the compactive effort, the smaller the difference between the
ranges of permeabilities achieved on both sides of the optimum. Clay compact-
ed dry-of-optimum was found to have an "open", flocculated structure, while
the wet-of-optimum tends to have a dispersed structure; this effect determines
the flow properties to such an extent that almost nothing is left from the
generally accepted belief that soil permeability and density are inversely
related. Lambe (1958) also noted that on the dry-of-optimum side, there seems
to be a threshold pressure 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 sixties by
Mitchell et al. (1965). In carrying out the investigation on a silty-clay
(the more general term "clayey-soil" is often used for silty-clay) for which
some of its mechanical properties were very well established, Seed and Chan
(1959) confirmed the above conclusions and new effects were simultaneously
revealed. Thus, combining different compactive efforts with different
moisture contents to produce a unique, quite high density soil (108 Ib/ft3
or 1.732 g cm"3), the permeability showed a slight increase with the water
content, on the dry side of optimum.
When samples were compacted again by kneading compaction using the same
compactive effort at different combinations 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.
The research conducted by Mitchell et al. (1965) indicated that when samples
are compacted at a moisture content below the optimum moisture, the K versus w
function depends on so many factors that, if precise information is needed,
testing of the soil is the only answer; it is essential to reproduce the field
conditions.
Any further increase in moisture content beyond the optimum moisture, results
in a tremendous drop in K-yalue. 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 using a kneading compactor at the same void ratio, the authors
47
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obtained a large range of K-values (over two orders of magnitude) using
different compactive efforts. 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.
The picture presented above refers to laboratory soil specimens compacted with
a kneading compactor, which has a better resemblance to 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 permeability reduction upon compaction is more prominent in
samples which were compacted using a kneading compactor rather than impact,
vibratory, or static compaction (Seed and Chan, 1959; Mitchell et al., 1965).
But it has been pointed out by Mitchell (1956) that clays, and presumably
clayey soils, are quite different in their behavior upon remolding. In
general, clay deposits which are believed to have been formed in marine or
brackish environments, are quite efficiently remolded, i.e. a preferred
orientation upon remolding can be achieved relatively easily; this conclusion
seems to be particularly true for clays which have been precompressed in
nature at very low stresses, e.g. the Scandinavian sensitive clays. The
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,
cannot be efficiently remolded since they already have an oriented structure
to start with, i.e. in their undisturbed state. Consequently, in establishing
the technology to be used for producing a soil liner, the designer should have
information on:
a. Natural preconsolidation pressure of the soil cover.
b. Conditions at formation or deposition of the soil considered.
This kind of information, associated with proper testing to reveal the sensi-
tivity upon remolding of the soil, should provide the designer with the
knowledge required to produce a soil-liner with a lower permeability.
Since soil compaction has been used intensively as a procedure for improving
the strength characteristics of soils, the sensitivity of a soil is the ratio
of the strength of the soil undisturbed to that of the soil after remolding.
Seed and Chan (1959) have indicated that about the simplest test for revealing
a sensitive structure is to compare the undrained stress-strain character-
istics 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 permea-
bility is the property to be considered and since soil flow properties have to
be at least as much structure sensitive as strength properties are, the
permeability rather than the strength has to 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 concentrate the eventual
effect that a particular structure might have on permeabilty.
The following conclusions should be observed when clayey soils are compacted
to produce the lowest possible permeability:
48
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a. The lowest permeabilities correspond, as a general rule, to the
condition when the soil is compacted wet-of-optimum moisture.
b. The sensitivity of a soil-clay-tactoid structure is ascertained
by increasing the available water and an available compactive
effort and measuring the decrease in permeability. The testing
program should reveal the relative significance of these two factors
and lead to the optimization of field compaction; the investigation
should identify the relative effects upon permeability of structural
versus 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 (K).
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 an increase in permeability by one order
of magnitude.
3.3 Admixed Liners
3.3.1 Introduction
A variety of admixed or formed-in-place liners have been used in the impound-
ment of water. The linings include asphalt, concrete, soil cement, and soil
asphalt, all of which are hard-surface materials. There has been a limited
amount of experience in the use of some of the admixes in the lining of
sanitary landiflls and the lining of impoundments of brine. They are also
undergoing exposure testing in two EPA research projects (Haxo and White,
1976; Haxo et al., 1977). In this section the following types of admixes are
discussed: hydraulic asphalt concrete, soil cement, and soil asphalt. Also
included is a discussion on the use of prefabricated asphalt panels for lining
water reservoirs. Bentonite clay, which can be considered as an admixed
material, was discussed in Section 3.2.
3.3.2 Hydraulic Asphalt Concrete (HAC) and Asphalt Panels
Hydraulic asphalt concretes, used as liners for hydraulic structures and waste
disposal sites, 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 - 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.
Hydraulic asphalt concrete can be compacted to have a permeability coefficient
less than 1 x 10~7 cm s-1. it is resistant to the destructive wave action
of water, growth of plants, and effects of weather extremes (temperature).
Such asphalt concrete is stable on side slopes, resisting slip and creep, and
49
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retains enough flexibility to conform to slight deformations of the subgrade
and avoid rupture from low level seismic activity. The hydraulic mix for
asphalt concrete is designed with a properly graded aggregate, and high
mineral filler and asphalt cement contents (Asphalt Institute, 1976).
Asphalt concrete liners may be placed with conventional paving equipment and
compacted to the required thickness (Asphalt Institute, 1966).
Styron and Fry (1977) used 11 percent asphalt in a two-inch asphalt concrete
liner to obtain the necessary permeability. Haxo and White (1976) 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 examined
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 least
97% of the density obtained by the Marshall Method (Asphalt Institute, 1976)
or less than 4% voids (Asphalt Institute, 1974). 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'1), 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 Insti-
tute, 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.
The choice of aggregate can also be a major factor in the design of a hydrau-
lic asphalt mix for use as a liner to confine wastes. The aggregate must be
compatible with the waste, e.g. aggregate containing carbonates should be
avoided if wastes are acidic.
50
-------
TABLE 3-3. PROPERTIES OF ADMIX LINERS MOUNTED AS BARRIERS3
Admix material
Cell No.
Particle size distribution of aggregate
Soil tests
Plastic limit
Asphalt tests
Penetration at 25 c
Penetration (extracted) asphalt
Softening point C ( F)
Viscosity, capillary at 60 C> cst
Viscosity, sliding plate at 25 c, at
0.05 sec" , HP
Viscosity, sliding plate at 25°C, at
0.001 sec" , HP
Microductility at 25°C, on
Tests on barrier specimens
Thickness of barrier, inch
Density, g./cm
Density, Ib/ft
Void ratio (vol. voids/vol. solids), %
Water swell, mil
Coefficient of permeability, cm/sec
Compressive strength, psi
Compressive strength after 24 h immersion1
% strength retained
'"Haxo and White, 1976.
^Composition) 7.1 asphaltilOO aggregate.
cComposition .- 9.O asphalt: 100 aggregate.
^Composition : 95 soil:5 Kaolin clayilO type
eComposition: 7.0 SC-800 liquid asphalt: 100
Asphalt concrete*5
7,13
68
14.5
20.0
40
2.2
2.387
149. 0
6.4
1.2 x 10"8
2805
2230
80
5 cement:8.8 water.
aggregate .
Hydraulic
asphalt concrete0
8,14
9.7
14.5
76
2.4
3.3 x 10~9
2712
2328
86
Soil cetnentd
9,15
4.5
0 q
1.5 x 10~ 6'
Bituminous Fabric -f
Soil asphalt6 seal* asphalt emulsion?
10,16 11,17 12,18
89 (192)
0.20 8.5 4.5
0.14 19.3 6.0
72 29
4 0.3 0.3
-3 -9 -9
1.7 x 10 J <10 <10
^Composition: Catalytically blown asphalt layer 4.7 kg/m2 (8.7 pounds per square yard).
gcomposition: Asphalt from emulsion spread on polypropylene nonwoven fabric - 4.8 kg/m2 (8.9 Ib. per square yard).
Measured on molded specimen.
^Asphalt cement and hydraulic asphalt cement immersed in water at 60°C; soil asphalt and soil cement at room temperature.
No Data
-------
TABLE 3-4. PERMEABILITY OF ASPHALT CONCRETE TO WATER3
in
Asphalt,
7.5
7.5
7.5
7.5
7.75
7.75
8.0
8.0
8.0
8.5
8.5
8.5
8.5
8.5
8.5
8.5
8.5
8.75
8.75
8.75
8.75
Compac-
tion,b
99.2
98.0
93.8
91.4
96.0
99.0
93.2
93.0
98.7
90.6
94.4
94.0
96.0
96.0
97.0
98.0
98.0
99.0
99.8
99.5
98.0
Voids,
2.8
3.9
8.0
10.4
6.9
2.9
8.0
8.4
2.6
9.5
6.0
6.2
4.2
4.2
3.2
2.1
2.6
2.3
1.7
2.0
3.6
Specific
gravity
2.248
2.223
2.128
2.072
2.147
2.240
2.115
2.107
2.240
2.067
2.147
2.144
2.189
2.189
2.313
2.236
2.224
2.226
2.240
2.232
2.197
Unit
weight
140.3
138.7
132.8
129.1
134.0
139.8
132.0
131.5
139.8
129.0
134.0
133.8
136.6
136.6
138.0
139.5
138.8
138.9
139.8
139.3
137.1
Maximum
specific
gravity
2.313
2.313
2.313
2.313
2.306
2.306
2.299
2.299
2.299
2.285
2.285
2.285
2.285
2.285
2.285
2.285
2.285
2.279
2.279
2.279
2.279
Permeability
constant,
millidarcys
7.6 x 10-7
1.6 x ID'7
1.05 x ID'4
1.53 x 10-3
1.97 x 10-6
9.7 x 1Q-7
1.3 x ID'4
1.3 x 10-3
<1.9 x ID'9
3.0 x ID'7
5.2 x 10'8
4.3 x ID'5
1.3 x ID'5
8.2 x ID'5
<4.8 x 10~9
<3.8 x lO'9
<5.5 x 10-10
<1.6 x lO'9
<9.6 x ID'10
<8.0 x 10-10
<1.2 x lO'9
Coefficient of
permeability
cm/ sec
7.9 x 10-7
1.7 x ID'7
1.09 x 10-4
1.58 x ID'3
2.04 x 10-6
1.0 x lO-6
1.31 x ID"4
1.3 x ID'3
<2 x 10'9
3.1 x ID'7
5.4 x lO-8
4.4 x ID'5
1.4 x ID'5
8.48 x ID'6
<5 x 10-9
<4 x lO'9
<5.7 x lO'10
<1.88 x lO"9
<9.28 x 10-1°
<7.79 x 10-1°
<1.21 x lO'9
ft/yr
0.82
0.18
112
1630
2.1
1.0
136
1340
<0.002
0.32
0.056
46
14
8.8
<0.005
<0.004
<0.0005C
<0.0016C
<0.0009C
<0.0007C
<0.001C
aHinkle, 1976.
bBased upon 35 blows Marshall = 100%.
cSamples still on permeability apparatus at time of this writing.
-------
Prefabricated asphalt panels have been used as liners for water reservoirs.
These panels typically consist of a core layer of blown asphalt blended with
mineral fillers and reinforcing fibers. The asphalt mix is molded under heat
and pressure, then placed between fabric sheets with a protective coating of
hot applied asphalt. The fabric sheets are usually asphalt impregnated felt,
plastics, or flexible glass fabrics. Panels are one-eighth to one-half inch
thick, three to four feet wide, and 10 to 20 feet long (Asphalt Institute,
1976, p. 21). The panels are rugged and flexible. They are flexible enough
to conform to and mold around irregularities in the subgrade, although bends
with a radius of less than 12 inches should be avoided. They are tough enough
to withstand abuse from pocket knives, razor blades, animal traffic, burrow-
ing and digging rodents, light vehicular traffic, and the erosive forces of
wind and waves. When properly installed and seamed, the panels form a rela-
tively smooth watertight seal exhibiting the resistance characteristic of
asphalt as described previously. Some problems occur with aging in hot dry
climates; volatile fractions are lost, causing the panels to become somewhat
brittle and to shrink. Thermal expansion and contraction of exposed panels
may cause "neck down" at joints, resulting in cracks and possible leaks.
These problems may be partially overcome by covering the portions exposed to
direct sunlight (Asphalt Institute, 1976). The panels may be joined by
lapping joints or butting together and seaming by use of batten strips. Hot
asphalt, cold asphalt mastic, or heat welding may be used in seaming.
3.3.3 Soil Cement
Soil cement is a compacted mixture of port!and 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 10~6 cm s~l (Stewart, 1978). To date, there have
been few studies performed to design a soil cement with very low permeabil-
ities (less than 10~8 cm s-1), as opposed to mixes designed for high compres-
sive strength. To reduce permeability of soil cement, coatings 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 Reclama-
tion, 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 optimum mois-
ture is that which results in maximum density of the compacted soil 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
those 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,
53
-------
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 water-
proof seal such as a hydrocarbon resistant or bituminous seal (Asphalt Insti-
tute, 1976).
3.4 Flexible Polymeric Membranes
3.4.1 Introduction
Prefabricated liners based upon sheeting of polymeric materials are of
particular interest for the lining of waste storage 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.
Liner technology is relatively new and a wide variety of liner materials are
being manufactured and marketed. These materials vary considerably in phys-
ical and chemical properties, methods of installation, costs and interaction
with various wastes. Not only are there variations in the polymers used, but
also there is considerable variation in the lining materials of a given
polymer type due to compounding, construction, and manufacturing differences
among the producers.
In this section, the lining industry, the various polymeric materials, and the
liner construction and methods of manufacture are described and discussed.
3.4.2 Description of the Polymeric Liner Industry
Although it is only a small part of the plastic and synthetic rubber industry,
the polymer liner industry has a unique hierarchy which needs to be examined
carefully (Figure 3-4). Basically, the industry breaks down into four major
segments:
- Raw materials producers
- Manufacturers of sheeting or roll goods
- Fabricators of prefabricated panels
- Installers or construction contractors.
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
54
-------
FLEXIBLE MEMBRANE LINER INDUSTRY
flaw Material Producers
POLYMERS
• Plastics
• Rubbers
Compounders
Manufacturers of Sheeting by:
Calendering
Extrusion
Fabricators
Assembly of Panel from Sheeting
installers
Construction
Owners
Cities, Counties
States
Industrial
Landfill Operators
FABRICS
• Scrim
SHEETING
• (roll-goods)
OTHER INGREDIENTS
• Fillers
• Plasticizers
• Vulcanizers
• Protectants
• Processing Aids
PREFABRICATED
PANELS
LINED FACILITIES
• Landfills
• Ponds
• Lagoons
• Pits
• Reservoirs
Figure 3-4. Basic structure of the polymeric membrane liner industry from raw
material manufacturers to liner installers. A representative
list of organizations and personnel in the individual segments of
the industry is presented in Appendix II.
55
-------
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 segments
of the industry are discussed in the following sections.
3.4.2.1 Raw Materials Production
The membrane or finished sheeting is made from raw polymer 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 polymer producers giving trade
names or other common identification and respective suppliers of the polymer.
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 industry. The
individual polymers are discussed in Section 3.4.3.
3.4.2.2 Preparation of Liner Compounds and Manufacture of
Sheeting and Roll Goods
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
often mixed on a mill or in an internal mixer, such as a banbury. The mixed
compound is then converted continuously into rolls of sheeting 48 to 96 inches
wide by hundreds of feet in length by calendering or extrusion. A description
of the manufacturing process is presented in Section 3.4.4. A representative
list of sheeting manufacturers is presented in Appendix II.
3.4.2.3 Fabrication
After calendering or extrusion, the sheeting is ready for fabrication into
panels. In this step the sheets or roll goods are joined (seamed) together to
form panels (up to 100 feet x 200 feet). The size of the panels is limited by
weight and the ability of a crew to place it in the field. Various seaming
techniques can be employed including, but not limited to: heat seaming,
dielectric seaming, adhesive systems, 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, eliminat-
ing field seaming altogether; this is called a drop-in liner.
56
-------
TABLE 3-5. POLYMER PRODUCERS AND SUPPLIERS
Polymer
Trade Name
Company
Butyl rubber
Chlorinated polyethylene (CPE)
Chlorosulfonated polyethylene (CSPE)
Elasticized polyolefin
Epichlorohydrin rubbers
Ethylene propylene rubber (EPDM)
Fluorocarbon polymers
Neoprene (chloroprene rubber)
Nitrile rubber (NBR)
Polybutylene (PB)
Polyester
Polyethylene - HOPE
- LOPE
Polyvinyl chloride
Thermoplastic elastomer
Urethane
CPEa
Hypalon
3111
Herclor
Hydrin
Epcar
Epsyn
Nordel
Royalene
Vistalon
Viton/Teflon
Neoprene3
Chemigum
Hycar
Krynac
NYsyn
Paracril
Hytrel
PVCa
Santoprene
TPR
Exxon
Columbian Carbon
Polysar
Dow Chemical
Du Pont
Du Pont
Hercules
B. F. Goodrich
B. F. Goodrich
Copolymer
DuPont
Uniroyal
Exxon
Du Pont
Du Pont
Denka
Goodyear
B. F. Goodrich
Polysar
Copolymer
Uniroyal
Shell Chemical
Du Pont
Many
Many
Borden
General Tire
B.F. Goodrich
Firestone
Pantasote
Stauffer
Tenneco
Union Carbide
Monsanto
Uniroyal
Many
a Generic name
57
-------
3.4.2.4 Installation
After the raw materials are produced, compounded, converted into roll-goods
and fabricated into panels, the installation is the final step in completing
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, the associated earthwork, and piping installation. The
installation is not complete until all field seams have been inspected to the
satisfaction of the end user or his representative. Air lancing and ultra-
sonic 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 systems to be used. They also can supply quality
control services during the installation of the liners.
3.4.2.6. Integration in the Liner Industry
Some companies perform two or more functions within the industry. For ex-
ample, some manufacturers of sheeting will also fabricate. Some installers
fabricate, other installers will design and supply engineering services.
3.4.3 Polymers Used in Liner Manufacture
Polymers used in the manufacture of lining materials are listed in Table 3-6.
They include rubbers and plastics differing in polarity, chemical resistance,
basic composition, etc. They can be classified into four types:
- Rubbers (elastomers) which are generally 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 and indicates
whether they are used in the 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, high-density polyethylene (HOPE), and low-density poly-
ethylene (LDPE). The thickness of polymeric membrane for liners range from 20
to 120 mils, with most in the 20-60 mil range.
Most of the lining materials are based on individual polymers; however,
plastics and rubber technology has been developing blends or rubber-plastic
alloys for improved properties. Consequently, it is difficult to make
generic classifications based on individual polymers of the liners though one
polymer may predominate in the compound. Blending of polymers introduces the
long range possibility of performance specifications being needed. However,
58
-------
Table 3-6 POLYMERIC MATERIALS USED IN LINERS
Polymer
Butyl rubber
Chorinated polyethylene
Chlorosulfonated polyethylene
Elasticized polyolefin
Elasticized polyvinyl chloride
Epichlorohydrin rubber
Ethyl ene propylene rubber
Neoprene (chloroprene rubber)
Nitrile rubber
Polyethylene
Polyvinyl chloride
Use
Thermo-
plastic
No
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
in liners
Vulcanized
Yes
Yes
Yes
—
—
Yes
Yes
Yes
—
No
No
Fabric
reinforcement
With
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
Yes
No
Yes
W/0
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
—
Yes
Yes
liner performance in the field cannot, at the present time, be defined by
laboratory tests.
Most of the membrane liners currently manufactured are based on unvulcanized
or uncrosslinked polymeric compounds which are thus 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 can be seamed with solvent or bodied solvent (a solvent
containing dissolved polymer to increase the viscosity and reduce the rate of
evaporation). 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 to be used for
potable water impoundment and have been in this type of service for about 30
years (Smith, 1980).
59
-------
Butyl rubber is a copolymer of isobutylene (97%) with small amounts of is-
oprene introduced to furnish sites for vulcanization (Morton, 1973, pp.
249-59). The important properties of butyl rubber 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 vulcanizates are highly swollen by hydrocarbon solvents and
petroleum oils, but are only slightly affected by oxygenated solvents and
other polar liquids. Butyl also has a high resistance to mineral acids.
After 13 weeks of immersion in 70% sulfuric acid, a butyl compound showed
little loss in tensile strength or elongation (Morton, 1973, pp. 249-59).
Butyl rubber has a high tolerance for extremes in temperature and retains its
flexibility throughout its service life. It has good tensile strength and
desirable elongation qualities.
Butyl rubber liners are manufactured in both reinforced and in unreinforced
versions. They are difficult to seam and to repair. They require special
room temperature vulcanizing adhesives (Kumar and Jedlicka, 1973; Lee, 1974).
3.4.3.2 Chlorinated Polyethylene
Chlorinated polyethylene (CPE) is produced by a chemical reaction between
chlorine and high-density polyethylene. Presently available polymers contain
25-45% chlorine and 0-25% crystallinity. CPE is compounded and used in
thermoplastic and crosslinked compositions.
Since CPE is a completely saturated polymer (no double bonds) it is not
susceptible to ozone attack and weathers well. The polymer also has good
tensile and elongation strength. Chlorinated polyethylene is characterized by
resistance to deterioration by many corrosive and toxic chemicals. Because
they contain little or no plasticizer, CPE liners 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. CPE will swell in the presence of high concentrations of aromatic
hydrocarbons and oils but regains some of its original properties when removed
from that environment. Continuous exposure to aromatics will shorten the
service life of the liner. In most cases CPE liners are not recommended for
containment of aromatic 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
60
-------
liners is CPE resin. CPE is widely used to improve the stress crack resist-
ance and softness of ethylene polymers and to improve the cold crack resist-
ance of flexible polyvinyl chloride. CPE membranes are available in varied
thicknesses in unreinforced or fabric reinforced versions (Bureau of Reclama-
tion, 1963, p. 23). Membranes of CPE are generally unvulcanized and thus can
be seamed by bodied-solvent adhesives, solvent welding or dielectric heat
sealing (Stewart, 1978).
3.4.3.3 Chlorosulfonated Polyethylene (CSPE)
Chlorosulfonated polyethylene is a family of polymers prepared by reacting
polyethylene in solution with chlorine and with sulfur dioxide. Presently
available polymers contain from 25-43% chlorine and from 1.0-1.4% sulfur.
They can be used in both thermoplastic (uncrosslinked) and in vulcanized
(crosslinked) compositions. Uncured CSPE is more thermoplastic than other
commonly used elastomers. It is generally tougher at room temperature, but
softens more 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 chemicals, e.g. acid and alkalies. It has good
resistance to growth of mold, mildew, fungus, and bacteria. Membranes of this
material are available in both vulcanized and thermoplastic forms, but pri-
marily in the latter. Usually, they are reinforced with a polyester or nylon
scrim and generally contain at least 45% of CSPE polymer. The fabric rein-
forcement 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.
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 extremes of temperatures or from weathering. Disadvantages of CSPE
membranes are low tensile strength, a tendency to shrink from exposure to
sunlight (Clark and Moyer, 1974, p. 20), and relatively poor resistance to
oils. Also, some CSPE tends to harden on aging, due to crosslinking by
moisture, ultraviolet radiation, and heat.
Membranes of CSPE are also available in colors other than black, without
appreciable loss of other desirable characteristics (Du Pont, 1979).
3.4.3.4 Elasticized Polyolefins
Elasticized pplyolefin 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 and
White, 1977). This membrane is unsupported and is manufactured by blow
extrusion and supplied in sheets 20 mil thick, 20 feet wide, and up to '200
feet long (Du Pont, 1979) which are shipped to site for assembly in the
field.
61
-------
Some difficulties have been encountered with elasticized polyolefin in low
temperature and high winds, in oily environments, and in adhesion to struc-
tures.
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 chloromethyl
side chains. The two types include a homopolymer and a copolymer of epichlor-
ohydrin and ethylene oxide. These materials are vulcanized with a variety of
reagents that react difunctionally with the chloromethyl group, including
diamines, urea, thioureas, 2-mercaptoimidazoline, and ammonium salts.
Epichlorohydrin elastomer vulcanizates exhibit the following 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 0 to 325"F. The copolymer shows
improved low temperature flexibility and is recommended for service from -40
to 300°F.
Epichlorohydrin elastomers can be seamed with room temperature vulcanizing
adhesives.
3.4.3.6 Ethylene Propylene Rubber (EPDM)
Ethylene propylene rubbers are a family of terpolymers of ethylene, propylene,
and a minor amount of nonconjugated diene hydrocarbon. The diene supplies
double bonds to the saturated polymer chain to be chemically active sites for
vulcanization, usually with sulfur. These rubbers vary in ethylene:propylene
ratio, in the type and amount of the third monomer, and in molecular weight.
Although EPDM liners are generally based on vulcanized compounds, thermo-
plastic EPDM liners are also available. Both versions are manufactured as
fabric reinforced and unsupported sheeting.
Liners based on vulcanized EPDM compounds have excellent resistance to weather
and ultraviolet exposure and, when compounded properly, resist abrasion and
tear. Because of its excellent ozone resistance, minor amounts of EPDM
are sometimes added to butyl to improve the weather resistance of the latter.
EPDM liners tolerate extremes of temperature, and maintain 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 halo-
genated solvents. ;
62
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Vulcanized EPDM membranes require the use of special cements and careful
application to assure satisfactory field seaming. The proposed seam construc-
tion should be tested in the use environment to assure serviceability.
Thermoplastic EPDM liners are seamed by thermal methods.
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 (Kumar and Jedlicka, 1973; Lee, 1974).
Neoprene sheeting for liners is vulcanized, thus vulcanizing cements and
adhesives must be used for seaming.
3.4.3.8 Polyethylene
Polyethylene is a thermoplastic polymer based upon ethylene. It is made in
two major types: (1) low-density polyethylene, and (2) high-density polyethyl-
ene. The properties of a polyethylene are largely dependent upon its crystal -
linity and density. High-density polyethylene polymers exhibit superior
resistance to oils, solvents, and permeation by water vapor and gases.
Unprotected clear polyethylene degrades readily on outdoor exposure, but the
addition of 2-3% carbon black can produce improved ultraviolet light protec-
tion. Polyethylenes, for the most part, are free of additives such as
plasticizers and fillers.
Both types of polyethylene have been used as liners. Membranes of low-
density polyethylene have been used unsupported for 15 to 20 years (Mickey,
1969) in lining canals and ponds. Recently, high-density polyethylene in
heavy sheeting has been introduced. The low-density polyethylene (LDPE)
available in thin sheeting tends to be difficult to handle and to field seam.
Also, it is punctured easily under impact such as when rocks are dropped on
the lining; however, it has good service puncture resistance as a buried
membrane lining. Linings of high-density polyethylene (HOPE) recently intro-
duced are available in thick sheets up-to 125 mil; special seaming equipment
has been developed for making seams both in the factory and in the field.
This type of liner is very stiff compared to most of the other membranes
described.
3.4.3.9 Polyvinyl Chloride
Polyvinyl chloride is produced by any of several polymerization processes from
vinyl chloride monomer (VCM). It is a versatile thermoplastic polymer which
is compounded with plasticizers and other modifiers to produce a wide range of
physical properties.
63
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PVC liners are produced in roll form in various widths and thicknesses. Most
liners are used as unsupported sheeting, but fabric reinforcement can be
incorporated. 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. There is a wide choice
of plasticizers that can be used in PVC sheeting, depending upon the applica-
tion and service conditions under which the PVC compound will be used.
Plasticizer loss during service is a source of PVC degradation. 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.
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 ultravi-
olet 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.
Plasticized PVC sheeting has good 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, ana oils. Special compounds of
PVC are available, designated as Oil-Resistant PVC (PVCOR), that possesses
high resistance to oil attack. These "oil-resistant" grades of sheeting must
be made with "specialty" plasticizers; the PVC polymer is inherently resistant
to the effects of oils.
Polymers such as nitrile rubber, CPE and EVA may be used to replace the liquid
plasticizers so that the PVC liner is not affected by the waste fluid.
3.4.3,10 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 the 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 a limited upper temperature service range, which, however,
is substantially above the temperatures encountered in waste disposal sites.
64
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Of particular potential interest for use in liners are the polyolefin thermo-
plastic elastomers such as thermoplastic EPDM, which are probably related to
the elasticized polyolefins, and m'trile rubber/PVC blends for oil resistant
liners. Such liner materials are now under development and test.
Nitrile/PVC thermoplastic elastomer blends have excellent 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 service-
able.
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 two basic methods used in the manufacture of polymeric sheeting are
calendering and extrusion. Calendering is used in forming both unsupported
and fabric reinforced sheeting, whereas extrusion is only used in making
unsupported sheeting.
Calendering is the more 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 3-5. The arrange-
ment for preparing a single-ply sheeting on a 3-roll calender is shown
in Figure 3-6. Unsupported sheeting is usually a 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.
Some manufacturers set up special straining operations to clean out all grit
that may be in the compound. This operation immediately precedes the
calendering. In this step, grit and other coarse particles are screened out
to yield a clean compound for the calender.
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 in order 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
reinforcement 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 have run to 20 x
20. Figure 3-7 shows several types of scrim. A coating is applied to the
finished scrim after weaving in order to tack the yarns in place so that the
finished scrim construction pattern will not lose its shape. Different
coating formulations are used, depending on the end use. Scrims or fabrics to
be used with vulcanized elastomeric lining materials are usually treated with
*
65
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Vertical
Vertical
Offset top roll
(a)
Inverted L
(b)
Inverted L
Figure 3-5. Roll configuration of calenders: (a) three-roll calenders, and
(b) four-roll calenders (Blow, 1971).
66
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FRONT
REAR
PRESSURE
ROLL
SPREADER ROLL V:
PENCIL BANK
WIND-UP
LINER
LET-OFF
Figure 3-6. Calender arrangement
bank (Banks, 1966).
- sheeting, one-pass or ply-up with pencil
67
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Manufacturer F 30 mils (0.76 mm). B-5602. Photo
P222-D-65685
Manufacturer A. 60 mils (1.52 mm). B-46O6. Photo
PX-D-68S86
Manufacturer G. 3O mils (0.76 mm). B-5540. Photo
PXD-68887
Manufacturer H. 30 mill (0.76 mm). B 5660. Photo
PX-D-68888
•igure 3-i Nylon-reinforced, butyl lining samples showing different weaves
and weights of nylon used by four manufacturers (6x magnifica-
tion). From Hickey, 1971.
68
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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 gauge polyethylenes,
thick sheets are extruded directly.
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 poses serious difficulties. Furthermore, most
of the spray-on materials that have been considered are thermoplastic and 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'2 (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
69
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toughness, decreased brittleness at low temperatures, and greater resistance
to aging (Chan et al., 1978, p. 17).
Bituminous seals are used on 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'2
to form a membrane about 0.04 in. thick.
b. An asphalt mastic containing 25 - 50% asphalt cement, the rest
being a mineral filler, squeegeed on at 5 - 10 Ib yd"2.
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
case, was reduced from 15.9 to 6.14 ft3 ft'2 yr'l (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 ff2 results in almost zero seepage. This product
has been used mainly in reservoirs and ponds (Wren, 1972).
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 ft-Vft2/
day. The seepage rate prior to placement of the liner was 9.9 ft^/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 (1964, 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 (1977) used an AC-40 grade asphalt cement as a lining material
in tests with two flue gas desulfurization (FGD) 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~2. 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 requires temperatures of 300 - 400°F for spraying
(Klym and Dodd, 1974).
70
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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 ^S and
SO?. Asphaltic liners exhibit variable to poor performance when exposed to
hydrogen halide vapors, but are essentially impermeable to water (Anonymous,
1966). Preparing pinhole-free membranes on large areas by spraying tech-
niques, 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. Fabrics of woven jute, woven or
nonwoven glass fiber, and nonwoven synthetic fibers have been used with
various anionic or cationic asphalt emulsions to form linings for ponds and
canals and as reinforcing patches under asphalt concrete overlays to prevent
"reflection" of cracks in the old pavement beneath. Seams in the supporting
fabric are often sewn with portable sewing machines after the fabric is
placed (Phillips Petroleum, 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 140CF continuous exposure and is not recom-
mended for prolonged exposure to hydrocarbon or organic solvents. It should
be applied only to properly prepared surfaces. The surface must be clean and
dry. Porous surfaces should be filled. Generally, a primer and a bonding
agent are applied prior to the application of the actual membrane. The
procedures for several base surfaces and the necessary precautions are provid-
ed 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
71
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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, 1972, pp. 30-40).
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 (Bureau of Reclamation,
1973, p. 13). 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 polymer-diesel fuel mixtures, petroleum based emulsions, powdered
polymers which form gels, and monovalent cationic salts (Bureau of Reclama-
tion, 1963, p. 115). See Table 3-7 for a list of representative soil seal-
ants.
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 clustered
soil particles more easily dispersed (Morrison, 1965, p. 1). Sodium carbonate
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. Some 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 (Morrison, 1965,
p. 2). 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 thickness in one project. The seepage was reduced only slightly from
16 to 14 ft3 ft-2 yr-1 (Day, 1970, p. 21). Soil sealants based on polymers
are generally 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 low viscosity slurry.
The low pH allows the slurry to penetrate the surface and form a deeper
seal.
Polymeric soil sealants may 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
72
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TABLE 3-7. REPRESENTATIVE SOIL SEALANTS*
Sealant
Application
Remarks
Cationic asphalt
emulsion
Oil soluble polymers
in diesel fuel
Farm ponds
Fresh water
Sodium tetraphosphate Sulfite liquor storage
Sodium carbonate
Lignin derivatives
gelled alum
Carboxymethyl cellu-
lose with alum
Petroleum emulsions
Attapulgite clay
Liquid elastomeric
polymer
Canals
Desalination byproduct
brine
Desalination byproduct
brine
Desalination byproduct
brine
Desalination byproduct
Fresh water
Requires approximately 19,OOOL/4,047 m2 (5,000
gal/acre) dispersed in water.
Injected beneath surface of water where seepage was
occurring.
Dispersant distributed in 15.2-cm (6-in.) layer of
soil at 2.3 kg/9 m2 (5 lb/100 ft?). Careful
compaction rendered soil impervious.
Wet-dry cycles disrupt water barrier. Used 183 g
(0.4 Ib) of reagent/0.84 m2 (yd2) of soil.
1% lignin. Cost $3,400/4,047 m2 (acre).
0.2% CMC. Cost $2,250/4,047 m2 (acre).
4% additive. Cost $4,400/4,047 m2 (acre).
2% Zeogel. Cost $1,000/4,047 m2 (acre).
Patent discloses several compositions, including
polyurethane elastomers.
Parks and Rosene, 1971.
-------
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
lining of waste disposal facilities. This type of liner functions primarily
by removing pollutants from the liquid waste as it passes through the liner
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 nonflowing 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).
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Chapter 3 - Lining Materials and Lining Technology
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Permeability, and Post-Construction Deflocculation Affecting the Proba-
bility of Pipe Failure in Small Dams. In: Proc. 5th. Int. Conf. on
Soil Mech. and Foundation Engineering. 2:422-446.
Anonymous. 1966. Chemical Resistance of Asphalt Coatings. Materials Pro-
tection. 5: 81-83.
The Asphalt Institute. 1966. Asphalt Linings for Waste Ponds. (IS-136).
College Park, Maryland. 10 pp.
The Asphalt Institute. 1974. Specifications for Paving and Industrial
Asphalt. (SS-22). College Park, Maryland.
The Asphalt Institute. 1976. Asphalt in Hydraulics. (MS-12). College Park,
Maryland. 65 pp.
Banks, S. A. 1966. Butyl Sheeting - Technology Review. EPL 6604 339. Enjay
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Blackmore, A.V., and T. J. Marshall. 1965. Water Movement Through a Swelling
Material. Australian J. Soil Res. 3:11-21.
Blow, C. M., ed. 1971. Rubber Technology and Manufacture. Butterworths,
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Boyes, R. G. H. 1972. Uses of Bentonite in Civil Engineering. In: Proceed-
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Brown, K.W. and D. Anderson. 1980. Effect of Organic Chemicals on Clay Liner
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Bureau of Reclamation. 1963. Linings for Irrigation Canals, Including a
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Burmister, D. M. 1964. Environmental Factors in Soil Compaction. In: ASTM
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Cheremisonoff, N., P. Cheremisonoff, F. Ellerbush, and A. Perna. 1979.
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Daniels, F., and R. A. Alberty. 1963. Physical Chemistry. 2nd ed. John
Wiley and Sons, Inc., New York. 744 pp.
Day, M. E. 1970. Brine Pond Disposal Manual. Office of Solid Waste Contract
No. 14-001-1306. Bureau of Reclamation, U. S. Dept. of the Interior,
Denver, Colorado. 134 pp.
Day, P. R. 1955. Effect of Shear on Water Tension in Saturated Clay. Annual
Report, I and II, Western Regional Research Project W-30. University of
California, Berkeley, CA.
Dow Chemical Co. 1977. CPE Resin Flexible Liner Brochure.
Du Pont. 1975. Flexible Membranes for Pond and Reservoir Liners and Covers.
Brochure E-23335.
Geier, F. H. 1964. Evaluation of Field Aging on the Physical Characteristics
of Buried Hot-Applied Asphaltic Membrane Canal Lining - Lower Cost Canal
Lining Program. Report No. B-34. Bureau of Reclamation, U. S. Depart-
ment of the Interior, Denver, Colorado. 75 pp.
Goodyear Tire and Rubber Co. 1973. Pond and Pit Liner Materials. 1004-1/73.
Hardcastle, J. H., and J. K. Mitchell. 1974. Electrolyte Concentration-
Permeability Relationships in Sodium Illite-Silt Mixtures. Clays and
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Haxo, H., and R. White. 1976. Evaluation of Liner Materials Exposed to
Leachate - Second Interim Report. EPA-600/2-76-255. U. S. Environmental
Protection Agency, Cincinnati, Ohio. 53 pp. PB 259-913/AS.
Haxo, H., R. Haxo, and R. White. 1977. Liner Materials Exposed to Hazardous
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Hickey, M. E. 1969. Investigation of Plastic Films for Canal Linings.
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Kays, W. B. 1977. Construction of Linings for Reservoirs, Tanks, and Pollu-
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Lambe, T. W. and R. V. Whitman. 1979. Soil Mechanics, SI Version. John
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79
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80
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CHAPTER 4. LINING MATERIALS IN SERVICE ENVIRONMENTS
4.1 Introduction
In Chapter 2, the various wastes which are destined for land disposal are
discussed with particular reference to their potential effects upon the inte-
grity of liners. In Chapter 3, various materials which might be used for
lining waste storage and disposal impoundments are described and their
properties discussed. In this chapter, we discuss the environmental effects
upon lining materials during service and the interaction of liners and wastes
that might exist in service environments.
Considerable information exists regarding water resistance of materials of
which linings are made, regardless of whether they are soils, asphalts, or
polymeric membranes. However, the wastes, although, most contain water, also
contain many other ingredients which have varying effects upon lining
materials. The pollutants, which liners are designed to prevent from entering
the groundwater, are generally not the aggressive agents in the waste liquids;
usually they are of relatively low concentrations. It is necessary to bear in
mind the totality of all constituents in a waste in assessing a liner material
for a given application; the chemical composition of both the waste and the
lining material must be considered.
Although there is much information on the effects of water on lining mater-
ials, no similar amount of information exists on the effects on lining
materials of chemicals and other fluids which might be found in the waste
streams produced by varuous industries. Considerable information is available
on the effects of chemicals and relatively simple mixtures of chemicals upon
many polymeric materials that are used as containers, tank linings, pipe
linings, and gaskets in direct contact with chemicals, solvents, and oils, but
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 Leachate (Haxo, 1976-1980)
Hazardous Wastes (Haxo, 1976-1980)
Flue Gas Desulfurization Sludges (Styron and Fry, 1979)
State-of-the-art Study of Liners (Stewart, 1978)
Field Verification of Liners (Pacey and Haxo, on-going)
Effect of Organic Chemicals on Soil (Brown, on-going)
81
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In this chapter, we discuss the known effects of various wastes upon indi-
vidual lining materials. Also discussed are the permeability of lining mater-
ials to wastes and gases.
4.2 Effects of Waste Fluids on Soils
Because soil permeability is the essential property which has to be considered
in the case of a soil liner, any alterations of a soil due to the presence of
a waste-leachate has to be identified. The most relevant characteristics
which can alter soil flow properties are:
a. the dispersing/flocculating tendencies of the soil when contacted by
the waste-leachate;
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, and
e. the modification of the adsorption properties of the soils.
Some of the possible changes will be indicated in the next paragraphs. Also
included is a discussion of the effect of some physical properties of the
waste-leachate on the performance of a soil-liner.
4.2.1 Discussion of Waste Fluids in Contact with Soils.
The composition and the relative quantities of different constituents in the
soil solution are in general "equilibrium" values. The soil solution is
simultaneously the cause and the effect of a particular set of properties of
the soil matrix. As soon as the soil solution is changed to a foreign solu-
tion (waste-leachate) the soil itself will tend to develop new properties.
This change is important since it allows us to assess the performance of
the soil liner in time.
4.2.2 Waste Fluids
To determine the effect of a specific waste on the permeability of a specific
clay soil liner, two unique fluids must be investigated. These are the flow-
able liquid constituents of the waste and the flowables generated from perco-
lating water leaching through the waste.
A waste's flowable constituents, hereafter referred to as the primary leach-
ate, includes both fluids in the waste (the solvent) and all components
dissolved in these fluids (solutes). The primary leachate of a waste depends
on the composition of the waste and may be aqueous-organic, aqueous-inorganic,
organic, or sludges as discussed in Chapter 2.
82
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Flowables generated from percolating water are composed of water (the solvent)
and all the components dissolved in this water (solutes). This flowable
mixture, hereafter referred to as the secondary leachate, may be aqueous-
organic or aqueous-inorganic, depending on the waste's composition.
The dominant liquid or solvent phase of a waste fluid may be water or any
organic fluid. The solute phase in a leachate are those chemicals that dis-
solve in the solvent phase. For example, in organic acids and bases, the
acid or base may or may not be the solvent phase while in inorganic acids and
bases, water is usually the solvent phase. Both primary and secondary waste
fluids can be divided into a solvent phase and a solute phase. While the
solvent phase will usually be the dominating factor controlling the leachate
effect on the permeability of a clay soil liner, the solute phase also has the
capacity to greatly affect clay permeability.
4.2.3 Solvent Phase of the Waste Fluids
4.2.3.1 Organic Fluid
Essentially all available literature on the behavior of organic fluids in
soils relates to systems where water is the solvent (Goring and Hamaker
et al., 1972). Water is viewed as the carrier fluid and the organic chemical
is in trace quantities. In the case of clay liners in direct contact with
concentrated organic fluids, the various equations for organic adsorption by
clay minerals have limited usefulness. More relevant to organic fluids
behavior in soils are basic chemical and physical properties such as dipole
moment and viscosity. Table 4-1 is a list of solvent phases studied and their
properties most likely to relate to their behavior in clay liners. Organic
fluids placed in waste disposal facilities cover the spectrum of chemical
species. The list is an attempt to select the most prevalent and represent-
ative of the fluids. The groupings of the organic fluids which will be
considered are acids, bases, neutral-polar and neutral-nonpolar.
The term "organic-acid" is used to represent any organic fluid that has acid
functional groups. This group of organic fluids is further divided to repre-
sent the two functional group types: phenolic and aliphatic acids. The group
has the potential to be very reactive with, and mobile in, clay liners.
"Organic-base" is the group to represent any organic cation. Since these
fluids are cationic, they will adsorb strongly to clay surfaces. By adsorbing
to the clays, these fluids have the potential for causing volume changes in
clays by changing interlayer spacings,- and also of dissolving certain con-
stituents out of the clay mineral. The two forms of organic bases represented
are aromatic amines and alkyl amines.
"Neutral-nonpolar" organics are those organic fluids that have no charge and
a small, if any, dipole moment. This group of fluids is further divided into
aliphatic and aromatic hydrocarbons. With no charge and little dipole moment,
these chemicals have the potential for moving through clay liners rapidly, and
eroding the pores through which they pass, thus increasing permeability.
These chemicals may also increase a clay liner's permeability by displacing
water from the clay liner which may in turn cause shrinkage.
83
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TABLE 4-1. POTENTIAL ORGANIC CHEMICALS IN WASTE FLUIDS
Relevant Physical and Chemical Properties
Organic chemicals
Type
Acid
Acid
Base
Base
Neutral -polar
0° Neutral -polar
Neutral -polar
Neutral -polar
Neutral -polar
Neutral -nonpol ar
Neutral -nonpolar
Neutral -nonpol ar
Neutral -nonpolar
Water
Aliphatic
Phenolic
Aromatic amine
Alkyl amide
Alcohol
Aldehyde
Alkyl halide
Ketone
Glycol
Alkane
Aromatic
Alkyl benzene
Mixed alkane
Name
Acetic acid
Phenol
Aniline
Formamide
Methanol
Butyraldehyde
Chloroform
Acetone
Ethylene glycol
Heptane
Benzene
Xylene
Paraffin oil
Temp, range
of liquid
state, *C
Melting
point
17
43
-6
2.6
-98
-99
-63
-95
-13
-91
5
-47
-8
0
Boiling
point
118
182
184
193
65
75
61
56
198
98
80
139
-•321
100
Density
0 20°C
(gm/cm3)
1.05
1.07
1.02
0.79
0.82
1.49
1.11
0.68
0.88
0.87
0.87
1.0
Viscosity Dielectric
@ 20"C constant
(centipose) 9 20'C
4.4
4.7
20.7
19.9
0.409
0.652
0.810
-•28
1
6.2
6.9
110
32.6
8.0
2.3
2.6
30
78.5
Water Vapor
solubility pressure
@ 20*C 0 20*C
(gm/1 ) (mm Hg)
11.4
82.0 0.2
34.0 0.3
... ...
92
71
160
0.05
... ...
0.003 53.0
1.8 76.0
0.20 6.5
...
17.5
Molecular
weight
60.05
94.11
93.13
32.02
72.10
119.38
62.07
100.21
78.11
106.16
-•375
18.02
-------
''Neutral-polar' organics have no charge but exhibit stronger dipole moments
than the "neutral nonpolar'' organics. This group of fluids is further
divided to represent its functional group types: alcohols
4.2.3.2 Water
tsJW-l 1"leveral WayS' " has a ver* St™n9 dipole
moment, 1.87 x 10 IB esu, which means a high tendency of water molecules
for orientation; this property makes the water a good solvent The propor? on
of dissociated water molecules on the average is very low, only one TeWv
ten Dillon; yet this minute ionization is" essential for many ration to
occur The dielectric constant of water (the tendency of water molecules to
orient to an electric or magnetic field) is quite high (approxStely 80)
this is the basis for adsorption of water on clay surfaces.
At 77°F water has a viscosity of almost one centipose; this is a hiqhlv
erature-sensitive property. The significance of viscosity for flow pVop
was shown previously, (Section 3.2.3.4). prop
The surface tension of the water (71.9 dyne cm-1 at 25'C) is responsible for
the capillary effect water retention properties, and consequent flSwprope?-
ties. The tension of the soil-water interface should extend only one to two
molecular layers (16 x 10-7Cm) for homogeneous surface sTnce clav
surfaces do not comply with this condition, the effect is present at much
larger distances away from the surface. present at much
Due to the sensitivity of water properties to the presence of solutes fsep
next paragraphs), a clayey soil liner may shrink, swell or heave, crack or
P1??- UK?!? T als.°Jncreasue th* hydraulic gradient that moves 'fluids in
soi . While water might not be the solvent in the waste's primary leachate
it is always the solvent in the secondary leachate. 'eacnate,
4.2.4 Dissolved Components in Waste Fluids
Organic chemicals are dissolved in a waste's leachate, regardless of what
fluid represents the waste's solvent phase. However, the relatve abundance
Of a given organic component of the solute will depend on what the sol Je£?
is. If, for example, the solvent is a nonpolar organic fluid, it would have a
large carrying capacity for solutes such as other nonpolar-organlcs If the
solvent is water, its carrying capacity for nonpolar organics in its solute
phase would be relatively small. it should be noted, however that man!
organic solutes (acids, alcohols, esters, ethers, amines ketones) reduce t
and* ?low ^^ '" WUh 1n)P°rtant rePercussi°^ on shrink-swell
in 9enera^cii"or9!n^ compounds, particularly electrolytes, do not 'change the
surface tension of the pore water. The presence of inorganic solutes in water
is, however important since they alter the water-clay react on via other
mechanisms with important consequences.
85
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Probably the most relevant effect induced by the presence of electrolytes in a
soil water phase is the flocculation of the clay particles. The Schultze-
Hardy rule, which applies in the case of "non-specific" electrolytes, states
that the flocculation value (the minimal concentration needed to flocculate a
dispersed clay soil) depends on the valence of the ions of opposite charge to
that of the clay particle; the larger the charge (valence), the greater the
flocculating power, and the flocculating value. Van Olphen (1963) indicates
an observed flocculation value of 25-150 mmol/L for trivalent ions. For
negatively charged clay colloidal particles, the flocculating power of cations
decreases in the order:
Cs>Rb>NH4>K>Na>Li
For positively charged aluminum and iron sesquioxides and broken edges of a
clay structure at very low pH values, the flocculating power of anions de-
creases in the order:
F>Cl>Br>N03>I>CNS
Another important feature of the clay-tactoid structure is that upon addition
of a low electrolyte concentration, lower than the flocculating value, the
clay becomes quite susceptible to flocculation. This can be achieved upon
addition of a polar or a low dielectric constant compound.
The flocculating capacity of electrolytes operates by depressing the thickness
of the "double-layer". Different types of flocculation are recognized:
face-to-face (FF), edge-to-face (EF), and edge-to-edge (EE). They result in
quite dfferent technological performances; thus, in dilute clay suspensions
viscosity increases when EF and EE flocculation occurs and decreases when the
clay flocculates FF.
Sometimes, the addition of a second compound affects the flocculation power of
the electrolyte; thus, when Na-polymetaphosphate is present in the system, the
flocculating value of the first compound - the electrolyte - is drastically
increased, which means a tendency of the clay to be in a dispersed state. On
the contrary, situations exist in which the presence of the second electro-
lyte lowers the flocculating value more than would have been expected if a
simple additive effect of the two electrolytes would have been operative.
From the information presented in the previous section, it should be clear
that apart from soil densification by compaction, soil structural features
(flocculated/dispersed structures) are important for assessing the suitability
of a soil liner. In this context then, a dispersed structure should be
associated with a desirable condition. At present, it is believed that one of
the main reactions which promotes a dispersion of the clay is the neutraliza-
tion of the positively charged sites of the clay, i.e. its "broken" edges.
The aluminum present in the octahedral layer forms an insoluble salt with the
anion which explains the anion over-saturation of the broken-edge and, conse-
quently, the generation of a negatively charged edge. Therefore, the
presence in the water phase of any anions which have a large valency and which
will tend to react with broken-edge octahedral aluminum in the manner de-
scribed above, should promote at least a partial dispersion, by deflocculating
the edge-to-face (EF) structure.
86
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Another mechanism by which a clay is dispersed is cation exchange. This
occurs anytime a low hydrated cation, e.g.Ca?4", is replaced by a cation,
e.g. Na+, for which a thick "double-layer" is characteristic.
Highly alkaline solutions and the corresponding solutes also have a dispersion
effect by the same charge-reversal mechanism. This type of peptization seems
to be particularly efficient in the case of kaolinite clays (Van Olphen,
1963, p. 117).
From this succinct description, it should be clear that the presence of
different inorganic compounds in the secondary leachates, their concentration,
and the characteristic pH should have a profound effect on the structure of
the clay and, consequently, on the performance of a soil liner.
4.3 Effects of Waste Fluids on Soils - Failure Mechanisms
4.3.1 Dissolution of Clay
pissolution 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 in large quantities, they are susceptible to
partial dissolution by either acids or bases.
pask et al. (1945) 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 niontmorillonite. Grim (1968) found the solubility of clays in
acid "varies with the nature of the acid, the acid concentration, the acid-to-
r-lay 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 in-
creased by pumping in acetic or formic acid. Johansen et al. (1951) reported
flow increases for water wells following their treatment with a solution
ntaining C1'tric acid. Grubbs et al. (1972) found acid waste as the probable
c sua1 agent in the permeability increase of carbonate-containing minerals.
x ray diffraction studies of the four clay minerals injected with acid waste
chowed them to be dissolved or completely altered. Diffraction peaks showed
the most variability with montmorillonite clays.
fleidization is the name used for the process of permeability increase by acid
ineral dissolution. This process is widely used to increase the permeability
nd hence the productivity of oil wells (Sinex, 1970).
ever present source of organic acids in waste impoundments is anaerobic
Hpcomposition by-products. These include acetic, propionic, butyric, iso-
hutvric and lactic acid. Anaerobic decomposition will yield the carboxylic
cid derivatives of whatever organic fluids are placed in the impoundment.
87
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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. Dissolution
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 (Anonymous, 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.
4.3.2 Volume Changes in the Soil
Volume changes of soils have to be understood since their occurrence can alter
the assumed density and flow properties of the soil liner.
Volume changes in clay or soil liners occur when there is a change in the
water content of the clay and when the soil can overcome the overburden
loading constraint. Adsorption of water on external surfaces occurs with all
three clay minerals if they are below saturation. For a given change in water
content, the magnitude of volume change is dependent on the clay mineral type,
the arrangement of the clay particles, the size of the clay particles, the
surface area per unit weight of the clay, the existing moisture conditions,
and on the kind and proportion of cations adsorbed to the clay. From Table
4-2, it can be seen that montmorillonite (and, to a lesser degree, illite) may
cause problems associated with changes in the volume of clay liners. Two
contracted lattice sheets of montmorillonite have a 2 nm thickness. The
adsorption of water on montmorillonite inter!ayer surfaces gives this type of
clay soil the potential for greater than a 200% difference in volume between
the dehydrated and hydrated state. This expandable lattice property of
montmorillonite is what makes its large volume changes unique. The structure
of the soil liner in operation will not be the same as the one immediately
following compaction. There are at least two reasons to suspect changes of
the soil structure following compaction:
a. Upon removal of compacting implements the stresses applied will relax
with the result that the soil will tend to rebound to a higher void
ratio. Even where this process takes place without loss of water
into the atmosphere, the magnitude of negative pore water pressure
will, in general, increase, and the expansion process should tend
toward a larger void ratio, the value of which depends on soil
elastic properties, the magnitude and persistence of stresses applied
during compaction,the overburden of the point-soil element consider-
ed, the void ratio achieved at the end of compaction, etc. If
superimposed on this, there is also a net loss of water in evapora-
tion, then there will be a simultaneous reduction of the original
volume of the soil. The reduction in volume can result in the
-------
TABLE 4-2. PHYSICAL AND CHEMICAL PROPERTIES OF THE CLAY SOILS
Clay mineral
Montmorillonite
(Lufkin)b
Calcium saturated
Hontmorlllonite
(Houston Black)C
00
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formation of microfissures which, in turn, can greatly alter the flow
properties of the soil liner while in service.
b. The compaction of a soil material into a soil liner generates, at a
given set of conditions, a certain characteristic structure with a
corresponding void ratio and, if the internal structure of the soil
is rigid, a certain set of flow properties. During compaction the
equilibrium soil structure and void ratios achieved depend on the
forces which oppose soil deformation, strongly correlated with the
characteristic swelling pressure of the system, i.e. soil-matrix and
soil-fluid compositions. Since the fluid composition during compac-
tion is different from the composition during service exposure,
changes in swelling characteristics have to be expected, and a
corresponding volume change of the soil liner can result if permitted
by constraining stresses.
Based on waste-effluent chemistry data, the soil engineer has to conceive a
hypothetical reaction between the soil liner and the waste effluent. The
testing of the hypothesis has to be performed in the laboratory using the
oedometer on remolded soil specimens. The testing should generate upon com-
pression, void ratio values similar to that encountered in the field and/or to
pressure values slightly over the expected overburden in the field. The
rebound curves have to be obtained in parallel with water and waste effluent.
The compression and swelling indexes have to be compared and the conclusion
should produce at least a semiquantitative set of information with regard to
the volume changes which may be expected during the operation of the system.
An alternative, indirect, and less expensive way of predicting the swell/
shrink behavior of a soil liner while in operation is to use Atterberg Limits
(Sections 3.2.3.1 and 5.2.2.1) together with percentage clay content of
the soil in the empirical relationship established by Seed et al. (1964).
S = 3.6xlO-5 A2-44 r.3-44
or
S = 2.16x10-3 (PI)2.44
where: S = percent swell under a surcharge of one psi
A = activity
C = percentage clay
PI = plasticity index.
Due to the character of these relationships, they will provide only approx-
imate information with regard to swell. Also, to serve the present purpose,
the PI in waste effluent can be determined.
If the general chemistry of the waste and the characteristics of the soil
indicate that no essential volume change of the soil liner will occur, then
90
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the soils engineer should review the most preeminent elements which determine
the shrink/swell characteristics of a soil system. Acccording to Mielenz and
King (1955) these elements are: the kind and amount of clay minerals present
in the soil, exchangeable composition, electrolyte concentration of the soil
solution, particle size distribution, void size characteristics, soil struc-
ture, and opposing normal load.
In this discussion on volume-change characteristics of a soil, it was tacitly
assumed that the greater the tendency 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 our case in which the original
soil solution is changed in the long run for the waste effluent. 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
distribution 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-effluent in a
realistic 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, undisturbed soil.
4.3.2.1 Shrinkage and Cracking
Extraction of interlayer water causes the shrinking and associated cracking
exhibited by montmorillonitic soils (Baver et al., 1972; Grim, 1968). Crack-
ing is a result of the clay undergoing three dimensional shrinkage. Where the
rate of water extraction is not uniform, cracks will form in wetter soil
(Yong and Warkentin, 1975). The water content of a clay liner may change if
an organic leachate displaces the water from the clay liner. To understand
more fully how much water will be displaced by what organic fluids, it is
necessary to first understand the nature and forms water takes in a clay
liner.
In clay liners, the clay particles are initially surrounded by multiple layers
of water. The thickness of the water between adjacent montmorillonite lattice
sheets will effect the plasticity, interparticle bonding, compactibility, and
water movement within a clay liner. These properties change as the thickness
Of the interlayer water changes (Yong and Warkentin, 1975).
Examination of the forces holding water to the interlayer surfaces in mont-
-orillonite will assist in predicting the effects of an intruding organic
leachate on the interlayer spacing.
tt is widely believed that water layers immediately adjacent to montmorillon-
.jte interlayer surfaces are nonliquid, hexagonally structured, and held much
more strongly than water layers further out from the surface (Grim, 1968).
91
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The thickness of this structured water varies depending on the adsorbed
cation. Montmorillonite has a structured water thickness of 1 nm or four
water layers per clay surface where calcium is the adsorbed cation. Sodium
montmorillonite gives a structured water thickness of 0.75 nm or 3 water
layers on its surfaces (Grim et al. 1945). Glaeser (1949) found the distance
between dehydrated montmorillonite layers exposed to acetone was 1.25 nm and
1.51 nm where sodium and calcium, respectively, were the adsorbed cations.
These surface-bound layers of water are held strongly to the clay. They
represent however only a part of the interlayer water. The water layers
further out from the clay surfaces are held in place by the large polarity of
water reinforced with its ability to hydrogen bond. This water chain extends
back to the structured water layers anchored to the clay surface. The outer
layers of water would easily be displaced by an intruding fluid. Where the
replacing fluid has a low dipole moment, a decrease in interlayer spacing
would probably result. If the intruding fluid had a higher affinity for the
clay surface than the structured surface layers of water, an even greater
decrease in interlayer spacing should be possible.
It may be possible for fluids with a high dielectric constant to displace
interlayer water. High dielectric constants in a fluid tend to ionize the
molecular species in the fluid. lonization in turn increases the amount of
adsorption onto clays for the ions. Asphaltenes and resins from the heavy end
of a crude oil were found to adsorb more readily to montmorillonite when they
were suspended in solvents of high dielectric constant (Clementz, 1976). A
major conclusion of the Clementz study was that ionized asphaltenes in an
aromatic solvent with a high dielectric constant may displace water from the
clay surface irreversibly. Consequently the clay was hydrophobic and had its
cation exchange capacity (CEC) reduced 52%. This CEC decrease would increase
the permeability of a clay to charged or polar organic chemicals.
When a fluid adsorbs to a surface, that surface is said to be wetted by the
fluid. Clay surfaces in a clay liner are water-wet initially. If a permeat-
ing organic fluid has a higher affinity for the clay surface, the clay may
become organic-wet. Petroleum engineers commonly refer to surfaces with oil
adsorbed as being oil-wet (Raza et al., 1968). Water and oil are said to
compete with each other for solid surfaces in oil reservoirs. A quantitative
measure of the preferential wettability of a clay surface for water and an
organic fluid can be represented as the difference between the water-clay and
organic-clay interfacial energies as represented by the Yong-Dupre equation
(Adams, 1941).
(Eorg:c) - Uw:c) = Uorgiw) (Cos 9)
where:
Eorg:c = interfacial energy per unit area between the organic and
clay (dyn cm'1)
Ew:c = interfacial energy per unit area between the water and clay
(dyn cm~l)
92
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.w =interfacial energy between the organic and water (dyn cm ~1)
9 = angle at the organic relayrwater interface measured through water,
(degrees).
There is no direct method for measuring either the organic relay or the water:
clay interfacial energy (Raza et al., 1968). Their difference, however, is
equivalent to the product of the waterrorganic interfacial energy and the
cosine of the waterrclayrorganic contact angle. This contact angle is easily
calculated from capillary rise measurements of the fluids.
If an intruding organic leachate displaces the anchored water layers, there
will be no forces holding the balance of the interlayer water against gravi-
tational drainage forces. In this case montmorillonite interlayer spacing
would decrease from 2 nm to whatever the interlayer spacing value would be for
the newly adsorbed organic fluid. Table 4-3 is a list of the interlayer
spacings for clay minerals after exposure to organic fluids. There is an
abundance of x-ray diffraction data for clay minerals with correlations
to the interlayer cation, dehydration temperature and the immersion fluids pH,
dielectric constant, and concentration (Grim, 1968; Theng, 1974; Barshad,
1952). The usefulness of this data is limited because as a matter of standard
procedure, the clay minerals are initially dehydrated. In order to simulate
more closely the situation in a clay liner, there needs to be a series of
x-ray diffraction studies on hydrated clay minerals. First, x-ray diffraction
data is needed for the clay liner saturated with water as it would be prior to
the impoundment of a waste. Secondly, x-ray diffraction data is needed for
the same clay liner after organic leachates have permeated the clay. If a
substantial interlayer spacing decrease is observed for the second set of
x-ray diffraction data, shrinkage cracks may be anticipated for that partic-
ular liner-waste combination.
jt is interesting to compare the interlayer spacings for an organic fluid at
different dehydration temperatures (Table 4-3). Dehydration at higher temp-
eratures removes more of the strongly adsorbed interlayer water. Subsequent
treatment with the organic fluid yields lower interlayer spacings for the clay
dehydrated at the highest temeprature. This is true to a lesser degree when
sodium rather than calcium is the interlayer cation. When the clay is de-
hydrated at room temperture (20°C) there is still water coating its surfaces.
However, both a neutral polar compound (N-butanol) and a neutral nonpolar
mixture (paraffin oil) reduced the interlayer spacing of the clay dehydrated
at 20"C over the interlayer spacing of the clay treated with water only after
dehydration. This indicates that even compounds less attracted to a clay sur-
face than water can displace some of the interlayer water and decrease inter-
layer spacing. If this scenario were to take place in a clay liner, even such
common neutral nonpolar organic solvents as xylene, benzene, heptane or
paraffin oil may decrease interlayer spacings and cause shrinkage cracks in
clay liners.
Another factor that will influence the interlayer spacing in montmorillonite
is the orientation of an organic interlayer cation. Greene-Kelly (1955) found
tne interlayer spacing of the clay with aniline adsorbed depended on the
93
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TABLE 4-3 INTERLAYER SPACINGS OF CLAY ORGANIC COMPLEXES ON MONTMORILLONITE3
Compound
Benzene
Benzene
Methanol
Ethanol
Ethanol
n-Butanol
n-Butanol
n-Butanol
n-Decanol
Paraffin oil
Paraffin oil
Water
Methyl ethyl ketone
B-Alanine
Inter! ayer
Ca sat.
.99
1.52
1.71
1.70
1.70
1.52
1.45
1.45
3.68
1.45
9.9
1.92
1.73
2.5
spacing
Na sat.
.99
.99
• • *
1.34
1.35
1.32
1.32
1.32
* • •
* • •
• • •
• • •
—
Dielectric
constant
20°C
2.3
2.3
32.35
25.00
25.00
17.70
17.70
17.70
5.0
2.10
2.10
78.5
18.85
150.0
Dipole
moment
0
0
1.66
1.70
1.70
1.66
1.66
1.66
1.7
0
0
2.74
• • i
Dehy-
dration
temp., °F
250
150
250
170
250
20
170
250
250
20
250
250
250
250
Barshad (1952).
concentration of aniline. Table 4-4 gives the interlayer orientation and
spacing with several aniline concentrations on a montmorillonite clay.
In a waste impoundment, the affinity an organic leachate has for the hydrated
clay surfaces will determine if it will displace the in-place water. Since
the clay surface is negatively charged, organic leachate components that are
polar or positively charged will have an affinity for clay surfaces. Since
the water on the clay surface is several layers thick, water solubility will
also improve an encroaching fluid's access to the clay surface. The strength
with which water is held to a clay surface will vary with the cations adsorbed
to the clay and the charge density of the clay. These factors may change from
one place to another in a clay liner. In order to predict interlayer spacing
and permeability of inplace clay liners, a series of x-ray diffraction studies
94
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TABLE 4-4 INTERLAYER ORIENTATION AND INTERLAYER SPACING IN
MONTMORILLONITIC CLAY a
-
Sorbed
fluid
Aniline
H20
H20
H20
H20
Orientation
Upright
Flat
Upright
Upright
Upright
Interlayer
cation
(meq/g)
Na (SAT)
Aniline (0.62)
Aniline (0.91)
Aniline (SAT)
Aniline (SAT)
Interlayer
spacing
(nm)
1.50
1.28
1.42
1.50
1.52
a From Greene-Kelly, 1955.
should be undertaken on the range of liner-waste combinations likely at a
given waste disposal site. If the leachate contains organic cations, the
charge density of the clay will affect the resulting interlayer spacing. Weiss
(1963) found the interlayer spacing after exposure to alkyl ammonium ions to be
1.3 nm, 1.9 nm and 2.76 nm for montmorillonites with low, medium, and high
charge density respectively.
/\ recent review of the interactions between montmorillonite and its interlayer
water is given by Low (1979).
4.3.2.2 Swelling
Swelling behavior in clays is dependent on what clay minerals are present.
Both kaolinite and illite are relatively low swelling while montmorillonite is
high swelling (See Table 4-2). Kaolinite and illite show the greatest volume
decrease on initial dehydration and very little swelling on subsequent rewet-
ting (Yong and Warkentin, 1975). This characteristic would limit the capabil-
ity for these two clays to "self heal" or to close shrinkage cracks once they
form. Montmorillonite clays exhibit both large and reversible volume changes
under normal conditions. However Gieseking (1939) found that montmorillonite
lost its ability to "self heal" or swell when exposed to organic cations.
mechanisms responsible for the reduction or
um bentonite (a clay in the montmorillonite
Hughes (1975) found three main
"eversal of swelling in sodiu
family)'
a. Adsorption of organics by the clay surfaces interferes with clay-
water interactions and blocks further swelling.
95
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b. The exchange of monovalent sodium for divalent calcium on the clay
surface causes a reduction and reversal in swelling.
c. Excess sodium will compete for available water with clay surfaces,
causing a decrease in the thickness of the water shell surrounding
the clay.
Clay structure refers to the arrangement of the plate-like clay particles.
The two extremes in this structure are the flocculated or edge-to-face
arrangement and the dispersed or face-to-face arrangement. Different sets of
forces are acting to attract and repulse clays from each other in these
structural forms. The forces acting on the clays also change with ion
concentration, ion valence, dielectric constant of the fluid around the clay,
temperature, size of the ions in both the hydrated and dehydrated states, pH,
and the clay's anion exchange capacity (Lambe, 1958).
It should be understood that organic leachates may cause either shrinking or
swelling of clay liners. Barrier (1978) reported swelling of montmorillonite
clays as a result of exposure to several forms of acetonitrile, xylene,
cyclopentane, alcohols, glycols, and ketones. A liner that swells and heaves
may loose its integrity during heaving, or it may shrink later when water
replaces imbibed organic fluids.
A clay's potential for volume change can be significantly related to its
Atterberg limit values. Table 4-5 shows these relationships for clays of
three swell potentials (Holtz and Gibbs, 1956). However, an actual quanti-
fication of a clay's swell potential would be much more complex. Some
of the factors listed by Bowles (1979) as effecting swell behavior in soils
were clay type, surcharge load, void ratio, method of saturation, and general
environmental conditions.
Table 4-5. SWELL POTENTIAL VERSUS ATTERBERG LIMIT VALUES IN THREE CLAY SOILS
Plastic range3
Shrinkage limit'5
Low
0-30
> 12
Swell potential
Medium
30-50
10-12
High
>50
<10
a The range of water contents below which the clay will behave as a fluid and
above which it loses its cohesiveness.
b The water content of a clay below which no further shrinkage occurs.
96
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It has been suggested that potential swelling is mineralogically determined,
and that exchangeable cations "perturb" rather than dominate the swell-shrink
characteristics (Ravina and Low, 1972).
Soil volume-change represents a very important potential mechanism of failure
of a soil liner.
4.3.3 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 react-
ivity 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 conse-
quently 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-equlibrium 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 local permeability of 1 x 10~5 cm s~l.
Differential solution and subsequent leaching, especially with calcareous
sediments, was reported to result in the formation of channels, sink holes and
cavities ( Mitchell, 1976). In this respect dissolution (the first mentioned
failure mechanism) 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.
97
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Crouch (1978) found that so called tunnels, tunnel-gullies, or pseudokarsts
will develop in dispersive soils where the soil-colloid bond strengths are low
compared to the energy of water flowing through the soil. He found dispersive
soils or those with low structural stability have been associated with tunnel
erosion throughout the world. Other factors found to be related to tunnel
erosion were ESP (exchangeable sodium percentage), soil cracks, low permeabil-
ity, and hydraulic gradients.
In a study of the variables effecting piping, Landau and Altsehaeffl (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 Altsehaeffl (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 montmorillonite. All the clays
slaked by dispersion when saturated with sodium with the process proceeding
faster with sodium kaolinite and sodium illite. Sodium illite swelled slight-
ly while dispersion of sodium montmorillonite was preceded by extensive
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.
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
V4 I »J f X« I w/IWII Y''MIW%*MH*WIW MIIWI I I I fc* W I I »• I I J 4»^f T ^ •
migrations. If there are fluid conducting p
these dispersed clay particles, permeability
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 1B% clay may be susceptible to soil piping.
Four laboratory tests for the determination of soil susceptibility to
dispersive 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
98
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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 #623.
4.3.4 Alteration of the Permeability of "as-compacted" Soil
Possible changes in the "as-designed" permeability can occur due to unpredict-
ed volume changes taking place in the soil liner during the operation caused
by pipin9 or directly by a change in soil structure without any change of
soil bulk volume.
As discussed in Section 3.2.3.2, the soil liner should be compacted at a
high moisture content, relatively high density and, a dispersed clay-struc-
ture; this situation will lead to the lowest possible permeability in "as-
compacted" state. In this condition, soil matric potential will have a
relatively high value (in the low negative range) and the incoming fluid
(waste leachate) will arrive as an unsaturated flow; therefore, the rate of
wetting of the soil element will be quite low. Under these circumstances, the
initial swell of the soil would be quite limited.
If, on the other hand, the waste fluid is very different in its chemical
composition from the water used during compaction, the incoming solution will
replace the original clay interlayer water and establish a new flocculation/
dispersion equilibrium. This may lead to volume changes, the significance of
which cannot be inferred from general knowledge. A rigorous testing program
can partially reveal soil volume change vulnerability and complementary
consequences on flow properties.
The occurrence of piping in dams is to a considerable extent connected with
the sharp boundary between two very different soil materials making up the
structure. If, in the case of a soil liner the underlying soil is texturally
very different, a high probability of piping can exist. If, associated with
this, the chemical composition of the waste fluid is such that internal
erosion of the soil liner is possible, the integrity of the liner becomes
Questionable. However, the most relevant change resulting in the overall
increase in soil liner permeability is probably the modification of soil
structure.
in different parts of this Manual, particularly in Section 4.2, emphasis is
niaced on the importance of the soil structure as reflected by the pore size
distribution. Also, the testing program discussed in Section 5.2 should
reveal the chemical sensitivity of the soil, i.e. its tendency to modify its
internal structure without mechanical deformation.
4.3.5 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
99
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highly populated areas, and since these are mostly flat areas; the disposal
sites will be pushed into hilly dissected topographical regions; economically,
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 frictional charac-
teristics of the soil, but rather with a proper estimation of the charac-
teristic 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.
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 undisturbed 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.
4.3.6 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.
100
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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.
Brant (1968) found an increase in the water permeability after a soil was
treated with para-tert-butylcatechol. He postulated that the increase was due
to the soil matrix being rendered more stable to water flow yielding a de-
crease in the migration of soil particles.
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.
4.4 Effects of Waste Fluids on Flexible Polymeric Membrane Liners
4.4.1 Introduction
Background information obtained in the field on the effects of waste fluids on
flexible membrane liners is limited. Consequently, most of this discussion of
liner materials to various waste fluids will be based upon laboratory and
simulated exposures. The principal experience in the field with membrane
liner materials has been with water impoundment and conveyance. There also
has been some experience with the impoundment of brines. The experience with
waste fluids, however, is relatively recent although membrane lined impound-
ments for waste water have been used since the 1960's.
Use of polymeric membrane liners for water conservation was started in the
ig40's and the first membranes were used for lining canals in 1948. These
liners were butyl-coated fiberglass. Later, a number of water reservoirs,
catchment basins, canals, and ponds were lined with butyl sheeting (A.R.
Dedrick, 1980; W. S. Smith, 1980; Lauritzen, 1967). A variety of other jjoly-
meric membrane liners were also developed based upon such polymers as:
polyviny1 chloride (PVC), polyethylene (PE), chlorosulfonated polyethylene
(CSPE °r CSM), and chlorinated polyethylene (CPE). These were all used in the
conservation, collection, storage, and 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
101
-------
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 sites
might have on the groundwater, the EPA initiated research work in this area.
They desired 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 using
community and to the public-at-large.
Two EPA projects have been undertaken to assess the effects of various wastes
upon a wide spectrum of potential liner materials which have been used in the
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 to hazardous wastes. These liner materials included flexible mem-
branes, soils, and various admixed materials. The membrane materials selected
for these studies were commercially available in 1973-1975 and were tested, if
available, at a single thickness of 30-40 mils. In this section, the avail-
able results of the exposures are summarized and the methodology briefly
described. These projects are reaching completion and final reports will be
forthcoming in the early part of 1981.
4.4.2 Exposure of Membrane Liners to Sanitary Landfill Leachate
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 4-1). An individual simulator consisted of a two-foot
diameter steel pipe, ten feet in height, placed on an epoxy-coated concrete
base (Figure 4-2). The specimen was sealed into the base with epoxy so that
leachate could not bypass the liner. Each liner specimen had a seam through
the center which was either made by the manufacturer or in the laboratory in
accordance with the standard practice recommended by the supplier. Approxi-
mately one cubic yard of 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
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
102
-------
GAUGE
%" DRAIN ROCK 3" THICK
SHREDDED REFUSE
MASTIC SEAL
CONCRETE BASE
SAND
SEALING RING
E
__— — •
\.
-3j
' >V
V
A.
,
^
\
'
t
:
/-
I*1
L 6
li
"'•-'•-i
• v '
'• <5
4
; \
^D '
. C3
\
•- ~ " b
^* k
0 % v •
' » ^ yj"
\ ' ^
ft Xj
'-^.jpftK'.^jui
- SOIL COVER
1% FT. THICK
- — POLYETHYLENE
^-SPIRAL-WELD PIPE
2 FT. DIA. x 10 FT. HIGH
^- LINER SPECIMEN
>yi-- DRAIN ABOVE LINER
GRAVEL
DRAIN BELOW LINER
Figure 4-1. Landfill simulator used to evaluate liner materials exposed
to sanitary landfill leachate.
tests normally performed on rubber and plastic materials. These tests are
1isted in Table 4-6.
TABLE 4-6. 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, ASTM D413
Puncture resistance, Federal Test Method Standard
No. 101B, Method 2065
Water vapor transmission, ASTM E96
Density and ash
Volatiles and extractables
103
-------
1 FT
s. \
SAND
EPOXY SEAL
MEMBRANE LINER
. .• x'lvieworiMiMc i_n\icn
' • ^£ ' • - ' - " - _— _— —— - i _—
w • • - • ^ ftwrwrwrfrrrrw9!t F t i
N|p£;@$£: 'GRAVEL.^;/ £$£/
*• Vi^i:iiiii^^C;^ •
BAG
Figure 4-2.
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.
A comparison of the swelling of membrane materials in water and in leachate is
presented in Table 4-7. The composition of the leachate at the end of the
first year of operation of the simulator is presented in Table 4-8. The data
show that the swelling in leachate is significantly higher than that in water
in spite of the dissolved Inorganic constituents in the leachate. This
increase in swelling is probably due to the organic constituents in the
leachate.
In Table 4-9 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 swel"
slightly more than the primary specimens which are exposed to the leachate on
only one side. The swell 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
104
-------
TABLE 4-7. WATER AND LEACHATE ABSORPTION BY POLYMERIC LINERS9
(Data in percent absorbed by weight)
Butyl rubber
Chlorinated polyethylene (CPE)
Chlorosulfonated polyethylene
Ethylene propylene rubber (EPDM)
Neoprene
Polybutylene
Polyethylene
Polypropylene
Polyvinyl chloride
Liner
no.
7b
22
24
12b
13C
23
3
4c
6b> 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
15.50
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
aHaxo, 1977.
bLiners mounted in generator bases.
cFabric-supported liner.
degree of swelling by the leachate. However, the composition of the leachate
was simultaneously changing, with the level of the organic constituents
dropping-
105
-------
TABLE 4-8. ANALYSIS OF LEACHATE3
Test
Value
Total solids, % 3.31
Volatile solids, % 1.95
Nonvolatile solids, % 1.36
Chemical oxygen demand (COD), g/1 45.9
pH 5.05
Total volatile acids (TVA), g/1 24.33
Organic acids, g/1
Acetic 11.25
Propionic 2.87
Isobutyric 0.81
Butyric 6.93
aAt the end of the first year of operation when
the first set of liner specimens were recovered
Source: Haxo, 1979.
TABLE 4-9. SWELLING OF MEMBRANE LINERS BY LEACHATE3
(In percent weight increase)
In landfill for 12 months
Membrane Liner
Butyl rubber
Chlorinated poly-
ethylene
Chlorosulfonated
polyethylene
Ethylene propylene
rubber
Polybutylene
Polyethylene
Polyvinyl chloride
Primary
specimens
2.0
6.8
• • •
12.8
5.5
• • •
0.02
• • •
3.6
• • *
Buried
specimens
1.8
9.0
20.0
13.6
6.0
0.3
0.3
5.0
3.3
0.8
Immersed
in leachate
8 mo.
1.4
7.9
18.6
12.1
2.9
-0.2
0
2.4
2.3
0.9
19 mo.
2.6
14.4
22.8
14.9
3.8
0.7
0.2
4.4
4.4
1.9
aHaxo, 1979.
106
-------
Typical of the results which have been obtained on the exposure to leachate
are those shown in Figures 4-3 through 4-5 regarding absorption of leachate,
tensile strength retention, and relationship of retention of tensile strength
and leachate absorption for various membrane lining materials that were
immersed in leachate for 8 and 19 months. The effects of 8 month and 19
months of immersion in leachate upon the S-200 modulus of the membranes are
shown in Table 4-10.
In Figure 4-3 the specific membranes are numbered on the bars. 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. Similar effects were observed for the
values of modulus and of tensile strength (Figure 4-4).
In Figure 4-5 the retention of tensile is plotted against the leachate
absorption for all pairs of data points measured at 8 and 19 months. These
data show a general downward trend of tensile strength with increasing
leachate absorption. Much of the loss in tensile strength can be attributed
to swelling per ^e_ and the reduced amount of rubber in the cross-section of
the tensile test specimen.
4.4.3 Exposure of Membrane Liners to Hazardous Wastes
The second contract 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
service, using actual wastes, to measure seepage through the specimens, and to
measure effects of exposure by following changes in important physical
properties 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 immersed in wastes.
- Primary exposure cells; one-side exposure to waste.
- Weather test; roof exposure.
- Weather test; small tubs lined with membranes and 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.
107
-------
TABLE 4-10. RETENTION OF MODULUS3 OF POLYMERIC MEMBRANE LINER MATERIALS
ON IMMERSION IN LANDFILL LEACHATE
Polymer
Butyl rubber
Chlorinated polyethylene
Chlorosulfonated polyethylene
Elasticized polyolefin
Ethylene propylene rubber
Neoprene
Polybutylene
Polyester elastomer
Polyethylene
Polyvinyl chloride
Polyvinyl chloride + pitch0
Liner
no.
44
12
38
86
3
6*>
85
36
8
18
83b
91
41
9
37
42b
90
98
75
21
11
17
19
40
67
88
89
52
S-200, psi
Unexposed
685
1330
1205
810
735
1550
1770
970
690
760
845
855
1040
1235
1635
-
1190
3120
2735
1260
2120
1965
1740
1720
1700
2400 -
2455
1020
8 mo.
590
1130
1070
790
395
1775
1360
1005
870
840
905
775
1035
975
1630
_
1245
3160
2790
1340
1845
1570
1545
1560
1570
1900
2370
870
Retention
% of original value
19 mo.
620
1190
1090
860
335
2070
1920
1050
860
830
900
790
1030
950
1640
-
1350
3150
2670
1285
1805
1640
1645
1570
1780
2105
2330
880
8 mo.
86
85
89
98
54
114
77
104
126
110
107
91
100
79
100
-
105
101
102
106
87
80
89
91
92
79
96
85
19 mo.
90
89
90
106
46
134
108
109
124
109
107
92
99
77
100
-
114
101
98
102
85
84
94
91
105
88
95
86
aAverage of stress at 200% elongation (S-200) measured in machine and transverse
directions.
^Fabric reinforced.
CS-100 values given; original and subsequent exposed specimens failed at less than
200% elongation.
108
-------
BUTYL "UBBIH
NIOMENI
'OLVIUTVLINt
fOLYIITlR ILAITOMIH
WLVITMVLINI
IB MONTHS I
UMN NO.
ABSORPTION OF LEACHATE, %
Figure 4-3 Swelling of membrane liners 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
CHLOROSULFONATED
POLYETHYLENE
ELASTICIZEO
POLYOLEFIN
ETHYLENEPROPYLENE
RUBBER
NEOPRENE
POLYBUTYLENE
POLYETHYLENE
POLYVINYL CHLORIDE
1 1 1 1 1
'I
1*" ""^ " 1
a i
•
1 1 f 1
a
KEY D
d 8 MONTHS IMMERSION
• 19 MONTHS IMMERSION 1 ^^1 1
1
100
TENSILE STRENGTH. * ORIGINAL
150
Figure 4-4 Retention of tensile strength of polymeric membrane liners on
immersion in landfill leachate after 8 and 19 months. Tensile
strength data were obtained by averaging the tests in machine and
transverse directions.
109
-------
B
':
u
LU
i-
5
11
o
U
:T
UJ
0.
KEY
O 8 MONTHS IMMERSION
• 19 MONTHS IMMERSION
75 -
10 20
LEACHATE ABSORPTION, %
Figure 4-5 Retention of average tensile strength of membrane liner materials
during immersion in landfill leachate as a function of swelling
by the leachate.
Details regarding the other exposures are available in EPA reports. (Haxo, 1978
and 1980).
4.4.3.1 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 4-11 and 4-12.
The exposure cell for the primary specimens is shown schematically in Figure
4-6. A similar type of exposure cell has been used for the thick admix and
soil liners (Figure 4-7). 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.
110
-------
TABLE 4-11. WASTES IN EXPOSURE TESTS
Phases
Type of Waste
Acidic
Alkaline
Lead
Oily
Pesticide
Organic
Name Phase
I
"HFL"a 0
"HN03, HF, HOAC"b 0
"Slopwater"a 0
"Spent caustic"*5 0
"Low lead gas washing" ) 10.4
) Blend
"Gasoline washwater" ) 1.5?
"Aromatic oil"b 100
"Oil Pond 104"b 89.0
"Weed oil"3 20.6
"Weed killer"b 0
Water Solids
Phase Phase
II III
100 0
100 0
100 0
95.1 4.9
86.2 3.4
89.1?
0 0
0 11.0
78.4
99.5 0.5
In immersion tests only.
In both primary exposure and immersion tests.
Type of waste
Acidic
Alkaline
Lead
Oil
pesticide
TABLE 4-12. WASTES IN EXPOSURE TESTS
pH, Solids, and Lead
pH
Name .. ,_ .
Water phase
"HFL" 4.8
"HNO , HF, HOAC" 1.5
"Slopwater" 12.0
"Spent caustic" 11.3
"Low lead gas washing" 7.2
"Gasoline washwater" 7.9
"Aromatic oil"
"Oil Pond 104"
"Weed oil" 7.5
"Weed killer" 2.7
Solids, % Lead,
Total Volatile ppm
•2.48 0.9
0.77 0.12
22.43 5.09
22.07 1.61
1.52 0.53 34
0.32 0.17 11
_
ca. 36 ca. 31
1.81 1.00
0.78 0.46
Source: Haxo, 1980a.
Ill
-------
-Top Cover
Epoxy
Cooting-
Bolt-
Waste
•Steel Tank
•Outlet tube with
Epoxy -coated
Diaphragm
IB
Caulking
Figure 4-6. Exposure cells for membrane liners. Dimensions of the steel
tank are 10 x 15 x 13 inches in width, length, and height.
-Top Cover
Epoxy
Bolt-
Flanged Steel
Spacer —•
.•
K
id—"
-
ID
Waste
•
:^^Neoprene Sponge Gasket
m 1
5t '
^Epoxy Grout Ring
ADMIX LINER
*~ Epoxy and Sand
Coating
^2s*asiss>fc'.<' "?« Crushed Silica v
^ ?&
-.
Wa
^-11
10"
w/
Z
. —
K .
^_rT
B^^^B
!
y
i=~Glos
Waste Column :
e Steel
10" x 15 x 12" High
Welded
" Flange
Outlet tube with
Epoxy-coated
Diaphragm
Screen-
To
.Collection
'Bag
Figure 4-7. Exposure cell for thick liners
112
-------
The first set of primary specimens 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 4-13 and 4-14. Table 4-13 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 devolatilized. Results show the variation in the
volatiles and extractables both with respect to the polymer type and the
waste. There are indications that, 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 4-14 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,
completely lost its elongation and that was in exposure to a strongly acidic
waste. The CSPE, neoprene, and EPDM 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.
4.4.3.2 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 4-15; the effects upon the elongation of the same materials are
shown in Table 4-16.
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.
113
-------
TABLE 4-13. VOLATILES3 AMD EXTRACTABLESb OF PRIMARY POLYMERIC MEMBRANE LINER SPECIMENS
AFTER EXPOSURE TO SELECTED WASTES
Compound data
Liner data
Polymer
Butyl
CPE
CSPE
ELPOe
i— •
•*» EPDM
Neoprene
Polyester
PVC
No.c
57R
77
6R
36
26
43
75
59
Volatiles, % Extractables, %
Waste and exposure time in days (d) Waste and exposure time in days (d)
Extractables,
Type % Unexposed
VZ
TP
TP
TP
VZ
VZ
TP
TP
6.4
9.1
3.8
5.5
18.2
13.9
2.7
35.9
0.29
0.00
0.29
0.15
0.50
0.45
0.26
0.26
Pesticide
1260 d
4.8
7.9
9.7
f
6.3
13.6
2.9
3.6
HNO3
1220 d
11.5
13.2
7.2
5.3
12.09
7.4h
f
Caustic
1250 d
1.4
2.8
5.8
f
1.3
5.7
0.9
1.8
Lead
1340 d
3.5
19.2
11.4
1.5
5.3
17.5
1.7
4.4
Pesticide
1260 d
7.6
9.4
5.4
f
25.2
16.1
5.8
33.4
HN03 Caustic
1220 d 1250 d
8.7 7.9
10.6 9.1
4.6 3.8
7.1 ...f
22. 8g 24.0
13 . 7
13. 5h 3.3
...f 35.6
Lead
1340 d
7.9
7.2
6.0
8.1
26.0
12.2
5.4
22.5
aPercent weight loss after 2h @ 105°C.
bAfter devolatization in air oven for 2h @ 105"C.
CNO. = Serial number of liner set by Matrecon; R = Reinforced with a fabric.
dType = Vulcanized (VZ) or thermoplastic (TP).
eELPO = Elasticized polyolefin.
fSpecimens still under exposure to waste.
gExposure time = 1150 days.
hExposure time = 509 days.
Source: Haxo, 1980a.
-------
TABLE 4-14. RETENTION OF ULTIMATE ELONGATION3 AND S-100 MODULUSb OF PRIMARY POLYMERIC MEMBRANE LINER SPECIMENS
ON EXPOSURE TO SELECTED WASTES
Ultimate elongation, % retention
Compound data
Liner data
Polymer
Butyl
CPE
CSPE
ELP09
01 EPDM
Neoprene
Polyester
PVC
NoV
57R
77
•6R
36
26
43
75
59
Typed
VZ
TP
TP
TP
VZ
VZ
TP
TP
Extract-
ables, %
6.4
9.1
3.8
5.5
18.2
13-9
2.7
35.9
Original
elongation? %
70
405
235
665
450
320
575
385
Waste and
Pesticide
1260 d
77
90
88
..."
103
84
87
93
exposure time in days
HN03 Caustic
1220 d 1250 d
419 142
88 115
83 68
96 ...h
791 95
95
-------
TABLE 4-15. ABSORPTION OF WASTE BY POLYMERIC MEMBRANE ON IMMERSION IN SELECTED WASTES
(Data in Weight Percent)
Data on liner
compound
Polymer
Butyl
CPE
CSPE
CSPE
ELPO6
EPDM
EPDM
Neoprene
Polyester
PVC
PVC
PVC
No.*
44
77
6Rd
55
36
83Rd
91
90
75
11
59
88
Type
VZ
TP
TP
TP
TP
TP
VZ
VZ
TP
TP
TP
TP
Extract-
ables, %
11.8
9.1
3.8
4.1
5.5
18.2
23.6
21.5
2.7
33.9
35.. 9
33.9
Pesticide
807 d
1.6
12.7
17.3
15.7
0.5
4.5
20.4
11.4
4.2
5.1
1.0
1.6
Haste
HNO3
751 d
3.8
19.9
10.0
10.9
7.6
4.2
50.9
17.4
6.4
22.1
-6.1
28.2
and immersion
HF Spent
caustic
761 d 780 d
3.7
12.9
9.0
7.7
1.1
3.1
23.9
12.0
2.0
18.1
0.9
14.3
0.8
1.1
4.3
3.3
0.6
1.6
1.3
1.5
1.5
0.4
-0.9
1.1
time in
Lead
786 d
28.7
118.9
120.7
116.2
17.0
24.8
34.7
59.1
7.4
-1.5
7.4
-5.2
days (d)
Oil Aromatic
104 oil
752 d 761 d
103.9
36.9
49.5
55.0
28.9
26.5
84.7
26.3
8.5
-10.4
-0.5
-9.8
31.2
226.4
105.2
110.5
29.4
19.8
34.2
142.6
16.6
18.5
28.9
14.1
Weed
oil
809 d
64.2
NDC
368.4
347.5
38.1
84.4
76.2
89.3
14. '7
15.3
24.7
25.2
aNo. = the serial number of liner set by Matrecon.
^Type = vulcanized (VZ) or thermoplastic (TP).
CHD specimen was lost; some indication that it dissolved in the waste.
^R = fabric reinforced.
eELPO = elasticized jjolyolefin.
-------
TABLE 4-16. VOLATILES CONTENT OF FLEXIBLE POLYMERIC LINERS
ON IMMERSION IN SELECTED WASTES
(Data in percent loss of weight)
Waste and immersion
Data on liner
Polymer
Butyl
CPE
CSPE
CSPE
ELPOh
EPDM
EPDM
Neoprene
Polyester
PVC
PVC
PVC
-?
44
77
6R9
55
36
83Rg
91
90
75
11
59
68
Type0
VZ
TP
TP
TP
TP
TP
VZ
VZ
TP
TP
TP
TP
Extract-
ables, %
11.8
9.1
3.8
4.1
5.5
18.2
23.6
21.5
2.7
33.9
35.9
33.9
compound
Volatiles
(unexposed) '
0;28
0.00
0.29
0.42
0.15
0.31
0.34
0.27
0.26
0.15
0.26
0.17
Pesticide
k 807 d
3.0
8.6
10.8
7.9
0.45
4.89
15.6
7.26
1.75
30.9
40.1
3.51
HNO,
751 d
3.8
20.4
10.4
9.1
7.2
3.1
22.6
13.7
28.0
22.6
10.6
23.2
HF
761 d
2.9
8.1
7.6
7.1
1.3
2.8
23.6
10.5
3.8
18.3
3.0
13.1
Spent
caustic
780 d
6.9
1.6
4.2
3.6
0.6
2.2
1.2
2.9
1.3
0.6
1.5
1.2
time in
Lead
786 d
15.3
42.2
3.3
1.1
9.5
13.9
18.5
23.6
6.1
16.1
12.7
11.5
days (d)
Oil
104
752 d
9.8
5.2
20.2
10.0
3.1
8.5
11.8
6.3
2.1
2.7
3.3
4.3
Aromatic
oil
761 d
3.3
NDe
6.1
4.8
1.5
4.4
4.2
3.9
3.4
3.6
4.6
3.5
Weed
oil
809 d
19.2
NDf
50.7
39.7
16.4
24.1
33.4
28.9
9.5
17.1
16.1
24.1
a "Volatiles" content is the loss in weight of a specimen of liner (unexposed or exposed) on air-oven heating for
2 hours at 105°C .
bNo. is the serial number of liner assigned by Matrecon for identification.
cType of compounds: vulcanized (VZ) or thermoplastic (TP).
dVolatiles content of unexposed specimens of liners.
eND = no data obtained because the sample was too badly deteriorated to test.
^Immersion sample was lost. Some indication that it dissolved in the waste.
9"R = fabric reinforced.
hELPO = elasticized £plyolefin.
-------
4.3.3.3 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.
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. Details of the test procedure
are presented in Appendix III-B. A schematic representation of the pouch
test showing the movement of the various constituents in shown in Figure
4-8.
CONDUCTIVITY
PH
D
AM
•MM
AA4
T
AAJ
AA4
blUNIZED
IWATER^
pST BAGS
\A/ A CTC -^
WAoTt ^
FLUID E
Ai
-*~P
WATER
SALTS/ ;
IONS
^— *
ORGANinp
^^^~ ¥
>n-*—" >?'SZ~ *
tVV
Hk^^AM^A,
lltT!
N
BS
V]
;
jJM::u::i::sa^
Figure 4-8. Schematic representation of the movements of the mobile constitu-
ents in the pouch (bag) test of membrane liner materials.
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.
Bags containing the wastes actually increased in weight, indicating the flow
of water into the bags through osmosis, as shown in Table 4-17. The long-term
tests now show that some ionic material is diffusing through the liners into
the deionized water.
118
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TABLE 4-17. RELATIVE PERMEABILITIES OF POLYMERIC MEMBRANE LINING
MATERIALS IN POUCH TEST WITH THREE WASTES*
Average flux into the pouch in grams per square meter per day x 10"2
Polymer
CPE
CSPE
ELPOd
PBf
PVC
PVC
Liner
nob
86
85
36
98
19
88
Nominal
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
Exposure time is 552 days unless otherwise
noted.
tylatrecon identification number
cPouch failed at 450 days.
^Elasticized polyolefin.
ePouch failed at 300 days
'PB - polybutylene
SPouch failed at 40 days
Table 4-18 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 CPE, CSPE, elasticized polyolefin, and poly-
butylene; the latter two are partially crystalline materials.
TABLE 4-18. PERMEABILITY OF THERMOPLASTIC POLYMERIC MATERIALS IN
OSMOTIC POUCH TEST
Time in days for electrical conductivity of water in
outer pouch to reach 100 wmho
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
aMatrecon identification number
&Elasticized polyolefin.
CPB = polybutylene.
119
-------
Table 4-19 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.
TABLE 4-19. POUCH TEST OF THERMOPLASTIC MEMBRANES3
Pouches filled with 5% NaCl solution
Polymer
Liner number0
Thickness, mils.
Volatiles content of exposed pouch wall, %
Change in weight of pouch plus waste, %
Change in weight of fluid in pouch
during exposure, %
Conductivity of water in outer pouch, pmho
Retention of physical properties, %:
Elongation
S-100
CSPE
6
32
8.7
+2.6
•K).95
585
95
106
ELPO
36
23
0.38
+0.71
+0.76
34
100
119
PVC
59
33
0.90
+0.38
+0.38
4500
94
120
Exposure time 1150 days (164 weeks).
^Elasticized polyolefin.
cMatrecon identification number.
4.4.4 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:
Vulcanized elastomers, e.g. butyl rubber, neoprene, EPDM, CSPE,
CPE, ECO, nitrile rubber, blends.
- Thermoplastic elastomers (TPE), e.g. CSPE, CPE, polyolefins,
blends.
Thermoplastics, e.g. plasticized PVC, PVC blends with selected
elastomers.
Crystalline polymers (thermoplastic), e.g. LDPE AND HOPE.
Note: CSM is the identification used in the liner industry for chlorosul-
fonated polyethylene
120
-------
Some of the polymers 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 (Hilderbrand and
Scott, 1950). For example, a hydrocarbon rubber like 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, will 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 chamicals.
Chemical stability means that the polymer does not degrade on aging which
would result principally in reducing its molecular weight causing swelling
and dissolving.
The soluble constituents of a rubber compound have a strong bearing on the
ability of that material to swell. Most polymers contain minor amounts of
solubles, e.g. salt, which are used in the manufacture of the raw rubber and
of the compound. The swelling is a result of the diffusion of water into the
compound. Soluble constituents can also arise from the compounding ingredi-
ents which are present in the compounding.
The effects that the first three factors have on the swelling of liner
materials is illustrated in Figure 4-9. The swelling of the thermoplastic
type of material in a fluid with which it is 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.
121
-------
LLJ
TIME
Figure 4-9. Types of swelling of polymeric membranes,
The swelling of crosslinked material is represented in Curve B, in which the
swelling reaches a plateau and changes only slightly with time. The level of
the plateau is determined by the degree of crosslinking and by the solubility
parameter of the waste fluid and the polymer.
Curve C represents a plasticized thermoplastic or a oil-extended rubber in
which the plasticizer is leached from the polymer. In this case, there is an
initial swelling and 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 usually has 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.
122
-------
- Increased permeability.
- Increased potential of creep.
- Greater susceptibility to polymer degradation.
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.
4.5 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.
4.5.1. 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 impermeability 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 more impermeable during the exposure.
Inhomogeneities in the admix materials, which probably caused the leakage in
the paving asphalt and soil asphalt liners, indicate the need for considerably
thicker materials in practice. Thicknesses of two to four inches were select-
ed for this 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.
4.5.2 Exposure to Hazardous Wastes
Five types of admix materials are being studied in this ongoing project:
- Compacted fine-grain native soil.
- Soil cement.
123
-------
- 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
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 containing 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 10'8,
2.43 x 10 "8, and 2.60 x 10 '8 cm sec -1. These figures indicate the
low permeability of the soil, which had a bulk density of 1.318 g cm~3 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
124
-------
was in the range of 7.0 to 7.6; the ratio, soil :solution, was 1:2 with
0.01 N CaCl2 being the equilibration solution.
In the case of the spent caustic, the pH values were around 9.0 for samples
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
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 unexpdsed 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
Tiners in ten cells. 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. The seepages collected
below the pesticide waste on both types of modified bentonite 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.
c 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.
125
-------
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 of 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.
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.
4.6 Compatibility of Liner Materials in Waste Fluids
4.6.1 Introduction
In Chapter 2 various wastes which must be contained are discussed with par-
ticular reference to their aggressiveness to various lining materials. In
Chapter 3, various liner materials which are candidates for the lining of
waste disposal facilities are described and discussed with respect to their
composition and characteristics.
The compatibility of a liner with specific waste is on of the first consid-
erations that a designer has in 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.
4.6.2 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
126
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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.
4.6.2.1 Characterizing the Waste
As has been indicated in Chapter 2, the waste fluids 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
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 liners:
- High pH, greater than 10.
- Low pH, lower than 3.5.
- Oily wastes.
- High temperature.
- Presence of exchangeable ions, e.g. calcium.
- Organic fluids and acids.
- Organic compounds, in general.
4.6.2.2 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 to compatibility 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
127
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of polymeric materials for the lining of many pipes, reactors, gaskets, etc.
which function in non aqueous media, acids, bases, etc. Generally, these
fluids are simple, that is the number of constituents are few. However,
there is wide experience with handling these various materials. Many of these
plastics and rubbers are used in outdoor applications and much information is
available on their durability and weatherability. Considering the available
liner materials, it is quite possible that some can be eliminated when con-
sidering the waste that must be contained.
4.6.2.3 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 4-20 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
compositions and characteristics. A rating of "good" indicates that 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.
4.6.3. 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 suitable 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.
4.6.3.1 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. Furthermore, 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.
4.6.3.2 Compatibility Testing of Soils
In Section 4.2 some of the testing of the soils which is necessary to deter-
mine the chemical sensitivity of the soil is described. The use of Atterberg
limits using the wastes as the fluid, when compared with the use of water,
will give an indication of the sensitivity of that soil. Also, the effect of
the waste upon permeability of soils is described in Section 4.2 and Appendix
III-D.
128
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TABLE 4-20. LINER-INDUSTRIAL WASTE COMPATIBILITIES3
ro
to
Caustic
Liner petroleum
material sludge
Soils:
Compacted clayey soils
Soil-bentonite
Admixes:
Asphalt-concrete
Asphalt-membrane
Soil asphalt
Soil cement
Polymeric membranes:
Butyl rubber
Chlorinated polyethylene
Chlorosulfonated poly-
ethylene
Ethyl ene propylene
rubber
Polyethylene (low den-
sity)
Polyvinyl chloride
P
P
F
F
F
F
G
G
G
G
G
G
Acidic
steel -
pickling
waste
P
P
F
F
P
P
G
F
G
G
F
F
Electro-
plating
sludge
P
P
F
F
P
P
G
F
G
G
F
F
Toxic
pesticide
formula-
tions
G
G
F
F
F
G
F
F
F
F
G
G
Oil
refinery
sludge
G
G
P
P
P
G
P
P
P
P
F
G
Toxic
pharma-
ceutical
waste
G
G
F
F
F
G
F
F
F
F
G
G
Rubber
and
plastic
G
G
G
G
G
G
G
G
G
G
G
G
aStewart, 1978. G = Good, F = Fair, P = Poor.
-------
4.6.3.3 Polymeric Materials
Three individual types of tests have been found useful in assessing the
effects of the wastes upon lining materials. These are:
- Immersion Test
- Pouch Test
- Tub Test
Each of these tests is described in detail in Appendix III-A, III-B, and
III-C, 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
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.
fouch 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.
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.
130
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4.7 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 4.3 the various failure mechanisms
relating to clayey 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
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 Manual.
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 4-21 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.
4.7.1 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.
131
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TABLE 4-21. 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
4.7.1.1 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 amnimals seeking water can also cause puncture.
4.7.1.2 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 failure 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.
4.7.1.3 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 is difficult to detect and control. Creep can
occur with any liner material.
4.7.1.4 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
132
-------
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.
4.7.1.5 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.
4.7.1.6 Differential Settling
Differential settling can damage all liners. This problem is best mitigated
with a thorough geologic analysis prior to site selection and careful subgrade
design and construction. Differential settling is a localized structural
stress phenomenon and the greater the thickness and elasticity of the liner,
the greater the tolerance range for differential settlement.
4.7.1.7 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.
4.7.1.8 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.
4.7.1.9 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
133
-------
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.
4.7.2 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.
4.7.3 Chemical Failure
Because organic and inorganic chemicals constitute a great majority of the
hazardous wastes to be contained in lined waste impoundment facilities,
chemical failures are of great importance and significance. The following
paragraphs describe the various types of chemical failure.
4.7.3.1 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 4.4.4.
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.
4.7.3.2 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 4.4.4.
4.7.3.3 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 the 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.
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).
134
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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
facilities 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 brings to the design and construction the guidelines of
the best available 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 be
responsible 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
materials will be described:
a. soils and clays
b. admixed materials
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.
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
recovery to improved reliability. Depending upon the type(s) of waste* the
period of containment, the surrounding climatic conditions, the available
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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 used 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. Frequently, where local geologic
considerations preclude the economical construction of excavated impoundments,
the desirable earth materials (sand, silt or clay) for berm and bottom con-
struction are 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 appropriate 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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co
Figure 5-1. An excavated impoundment (Duvel, 1979)
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Figure 5-2. Diked pond partially excavated below grade (Duvel, 1979).
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Figure 5-3. A cross-valley pond configuration (Duvel, 1979)
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be removed for use elsewhere and that the soil excavated may shrink 5 to 20
prcent between excavation and placement in an engineered fill.
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
TABLE 5-1. FACTORS TO BE CONSIDERED IN THE SITE PLANNING/
CONSTRUCTION PROCESS
Characteristics of the waste to be impounded
Characteristics (type and texture) of "in situ" soil materials
Subgrade characteristics - 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/outflow/overflow conveyances
Monitoring/leak detection systems
Cover material availability/characteristics
Proximity to major waste generators
Proximity to residential and commercial areas
Coupon testing and evaluation, if applicable
Weed control
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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.
5.2.1 General Discussion
Because of soil variability and the scale of the operation, in the case of
designing and constructing a soil liner, a relatively larger flexibility has
to be provided by the designer in the specifications required. These
specifications have to be both essential and operational; they have to be
stated in terms of performance required from the soil liner and also 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 the 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.
70 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 at 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
have to state clearly the working procedures for every soil type or unit so
that the end result will be a uniform soil liner.
The working procedures indicated in the design specifications for a particular
soil unit normally would be easy to observe if the soil cover were to have a
uniform moisture content and density characterization in the undisturbed
state; oftentimes, though, there is a soil intraunit heterogeneity which
can escape observation during the the reconnaissance investigation. The
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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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slight adjustment of the instructions to the newly discovered state of the
soil depends on the competence of the working group.
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 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 has to 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 required moisture-content of the undisturbed 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-
1ayer.
e. The weight of the compacting implement.
f. The type of compacting implement.
g. Possibly the trade-name of the compacting implement.
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-
eability.
c. Absorptive capacity for pollutant species.
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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 CaSCty
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.
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 as 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
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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 D1557 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 that a soil K value is independent of the volume of soil,
the volume of fluid passing, and the hydraulic gradient moving the water:
J = -S- . KAH
A
where:
J = flux of a fluid (cm3cm"2s~l)
Q = flow (cm3 s'1)
K = permeability coefficient (cm s~l)
AH = hydraulic gradient
A = cross-sectional area of flow (cm^)
and since:
t
where:
V = volume of fluid (cm3)
t = time (s)
therefore:
" AUH .
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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
n1
where:
K1 = IPC expressed in the c.g.s. system as cm?
K = permeability (cm s~l)
n1 = kinematic viscosity (cm^ s~l)
with
n1 =
n = viscosity (g cm~l s~l)
p = density (g cm~3)
G = gravitational constant, 981 cm s'2 at 45* latitude.
n
P
Viscosity normalizes a fluid's resistance to flow due to its cohesiveness,
while the fluid's density values normalizes 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 organic fluids being placed in
waste impoundments is being investigated to determine their effects on the
permeability of clay liners. Central to these tests has been 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-D.
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.
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5.2.2.4 Permeability to Waste Fluids
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 the modified Atterberg Limits test plus some pilot or laboratory scale
permeability testing should be conducted. Presented in Appendix III is an
experimental permeameter which can be used for accelerated testing.
5.2.2.5 Determination of Soil Strength Characteristics
It is well known that in laboratory testing of a soil for strength charac-
teristics, the relevant failure mechanism of the soil in the field should be
well understood. 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 confinement and then deforms in shear
without change in volume, can be duplicated in the laboratory in a consol-
idated-undrained triaxial compression test (CU-test). For this purpose, ASTM
D 2850 should be used with the provision that volume changes are permitted
while the sample is under T3loading (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.
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 clayey soils are important not only with regard to
slope stability, but also with regard to the task of compacting the soil at 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).
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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 in initial compaction 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.
When the topography of the waste disposal site is flat, soil strength charac-
teristics are of little concern. Environmentally, a disposal site should be
placed as far away as possible from highly populated areas, which are mostly
flat areas. The disposal sites may consequently be pushed into hilly, dis-
sected topography regions. A hilly region has its advantages in that placing
the waste in a ravine may involve generally less earthwork and results in a
higher efficiency of waste storage per unit disposal area. In many situa-
tions, the waste disposal site floor will slope and so will the soil liner.
For this situation, an investigation of stress-strain and strength properties
of the soil should be conducted. The difficulties associated with the anal-
ysis of slope stability are not associated with the usual difficulty in
properly determining the cohesional and functional characteristics of the
soil, but rather with a proper estimation of the characteristic hydrology of
the site under operating conditions; 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.
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
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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.
As Mitchell (1969) 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, 1969), 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 the minimal structural
effect; in this range of moisture content densification because of a higher
compactive effort is not associated with a considerable deflocculation of the
soil structure. The 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 magnitude 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 more deflocculated (weaker) structure.
The method of compaction has also 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 static or a kneading compaction procedure is
used on the dry-side-of optimum, the characteristic structure of the soil will
be the flocculated and, at the same moisture content and density, the strength
will be unaffected by the method of compaction. In the high range of mois-
ture content, the kneading compaction is much more efficient in deflocculating
the structure and, at the same density and moisture content, the soil is
considerably weaker than the soil compacted statically. Seed et al. (I960)
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 com-
pactive effort and the method of compaction.
The observation revealed by the work performed at the University of Califor-
nia, Berkeley, 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 small 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
generated, in a statically compacted sample, a structure similar to the one
characteristic for the sample prepared by the kneading compaction procedure,
i.e. a dispersed one, which raises an important practical problem: in assess-
ing the value of the shear stress for a particular design purpose, considera-
tion has to be given to the range of meaningful strains.
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Since the problem is one of slope stability, a safe procedure would be to
consider the "ultimate" value of strength (Lambe) or the "residual" one
(Skempton), 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 clayey 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 by another 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 reaction 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 (CU) 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 ( °3 = 2.0 kg cm'2), it was shown that
the lower the moisture content during compaction (the more flocculated the
structure), the larger the deviator stress at any particular strain. Simul-
taneously, the pore-water pressure was higher with larger compaction moisture
content so that the effective principal stress ratio or the effective
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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 characteristics-structure-
pore-water pressure strength (Mitchell, 1964, p. 89).
5.2.3 Designing Soil and Clay Liners
As a hydraulic structure, the soil liner shall be designed with the main
purpose of obtaining a blanket which will considerably impede the downward
movement of the waste liquid into the underlying, undisturbed soil. 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-
eability of the site.
Another facet of the design process for a soil and clay liners is the provi-
sion for keeping adequate construction records and documentation 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 considered 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 wi.l 1 produce an error on the safe side.
The starting point of the analysis for design should constitute the limiting
seepage, the permissible flux qrj, 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)
157
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c. The attentuation capacity of the underlying soil and its capacity to
render groundwater contamination less probable.
d. Groundwater characteristics
- Depth
- Flow rate.
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 aquifer).
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 VII.
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 compactibility 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 similar soils.
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 qp. 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 (Kp). 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 moistureof the soil during
compaction and the corresponding density. If, in the tentative
158
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LU
o
CD
O
c/5
SOIL MOISTURE CONTENT, W
m
<
LU
2
cc
LU
O.
O
(Si
-OPTIMUM MOISTURE
SOIL MOISTURE CONTENT, W
m
<
LU
2
cc
LU
a.
BOTH DRY AND WET OF OPTIMUM
.MAXIMUM DENSITY,
P max.
SOI L BULK DENSITY, P
Figure 5-4. 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 1).
159
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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
-------
z
LU
Q
m
SOIL MOISTURE CONTENT, W
X
\-
oo
<
cc.
LU
a.
Kp
OPTIMUM MOISTURE
SOIL MOISTURE CONTENT, W
m
LU
oc
LU
Q.
O
CO
MAXIMUM DENSITY,
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).
161
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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.
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 sidewall/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
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.)
162
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Figure 5-6. Typical earthwork equipment used during impoundment construction,
dozer with blade (top) and dozer with compactor and blade (bot-
tom) .
163
-------
Figure 5-7. Trenching machine for anchor trenches (top)
mover for berm construction (bottom).
164
Dozer and earth
-------
••
Figure 5-8. Conveyer system used during impoundment construction.
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) an impervious base layer, (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 overlying liner
from penetration by the permeable lattice materials; fabric materials (like
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 lining) working into the interceptor material. Filters can be con-
structed 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."
165
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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). It is advised by Kays (1977) that the con-
veyances 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 offiste.
A critical need for an adequate drainage system will exist if groundwater is
present immediately below the impoundment. A well designed underdrain system
will mnimize or eliminate (1) reverse hydrostatic pressure and (2) removal of
soil from beneath the liner due to groundwater flow. Reverse hydrostatic
pressure occurs when the groundwater level exceeds the operating water level
in the impoundment. This could occur, for example, during normal level
fluctuations in a drinking water reservoir. The groundwater reverse pressure
can then push on the back side of the lining system, causing liner failure.
Soil may be removed by groundwater flow below a liner, eventually causing the
liner to rupture. If possible, sites where high groundwater exists should be
avoided.
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 open pipes into which a water sampler can be lowered.
5.2.4.4 Field Compaction of Soil for Construction of Liner
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 clayey 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
sidewall 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.
166
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Table 5-3.
COMPACTION EQUIPMENT AND METHODS8
Requirements for compaction of 95 to 100 per cent Standard Proctor,
maximum density
Equipment
type
Sheepsfoot
rollers
Applicability
For fine-grained soils or
dirty coarse-grzlned
soils with more than 301
passing No. 200 mesh; not
suitable for clean
coarse-grained soil s;
particularly appropriate
for compaction of Imper-
vious zone for earth dam
or linings where bonding
of 1 ifts 1s Important .
Compacted Passes or
11ft coverages
thickness,
in. 1cm)
6
05)
4-6 passes
for flne-
grained
soil;
6-8 passes
for coarse-
g r a 1 n e d
soi 1
Dimensions
Soil type
Fine-grained
soil H > 30
Fine-grained
soil PI < 30
Coarse-grained
soil
and weight of
Foot
contact
area.
in. 2 (cm?)
5-12
(32 - 77)
7 - 14
(45 - 90)
10 - 14
(64 - 90)
Efficient compaction of wi
equipment
Foot
contact
pressures.
psl(MPa)
250 - 500
(17 - 34)
200 - 400
(1.4 - 2.8)
150 - 250
(1.0 - 1.7)
at soils re-
Possible variations In equipment
For earth dam, highway, and
airfield work, drum of 60-in. dla.
(152 cm), loaded to 1.5-3 tons
per lineal ft (43.7 - 87.5 kN per
lineal m) of drum generally is
used; for smaller projects, 40-in.
dla (101 cm) drum, loaded to 0.75
to 1.75 tons per lineal ft (21.9 -
43.7 kN per lineal m) of drum Is
used; foot contact pressure should
be regulated so as to avoid
shearing the soil on the third or
fourth pass.
quires less contact pressures than the
same sol Is at lower moisture contents.
Rubber tire
rollers
Smooth wheel
rollers
Vibrating
baseplate
compactors
__ —
Crawler
tractor
Power
tamper or
rammer
For clean, coarse-grained
soils with 4 - B% passing
No. 200 mesh.
For fine-grained soils or
lie 1 1 gr ided , dirty
coarse-grained soils with
more than 8X passing No.
200 mesh.
Appropriate for subgrade
or base course compaction
of well-graded sand-
gravel mixtures.
May be used for fine-
grained soils other than
in earth dams; not
suitable for clean
well-graded sands or
iHty i'nif"r» sir-ds.
For coarse-grained soils
with less than about 12*
passing No. 200 Mesh;
best suited for materials
with 4 - 8* passing No.
200 mesh, placed thor-
oughly wet.
Best suited for coarse-
grained soils with less
than 4 - 8X passing No.
200 mesh, placed thor-
oughly wet.
For difficult access,
trench backfill; suitable
for all Inorganic soils.
10
(25)
6 - 8
(15 - 20)
8 - 12
(20 - 30)
6 - 8
(15 - 20)
8-10
(20 - 25)
10 - 12
(25 - 30)
4-6 in (10
- 15 cm)
for s1H
or clay; 6
In . (15
cm ) for
coarse-
graded
soils
3-5 Tire inflation pressures of 60 to 80 psl
(0.41 - 0.55 MPa) for clean granular
material or base course and subgrade
compaction; wheel load 18, MO - 25,000 Ib
4-6 (80 - 111 kN); tire inflation pressures
in excess of 65 psi (0.45 MPa) for fine-
grained soils of high plasticity; for
uniform clean sands or sllty fine sands,
use large size tires with pressure of 40
to 50 p$1 (0.28 - 0.34 MPa).
4 Tandem type rollers for base course or
subgrade compaction, 10 - 15 ton weight
(89 - 133 kN), 300 - 500 Ib per lineal
In. (3.4 - 5.6 kN lineal cm) of width of
real roller.
6 3-wheel roller for compaction of fine-
grained soil; weights from 5-6 tons (40
- 53 kN) for materials of low plasticity
to 10 tons (69 kh) fur materials of high
plasticity.
3 Single pads or plates should weigh no
less than 200 Ib |0.89 kN); may be used
In tandem where working space 1s avail-
able; for clean coarse-grained soil,
vibration frequency should be no less
than 1,600 cycles per minute.
3-4 No smaller than DB tractor with blade,
34,500 Ib (153 kN) weight, for high '
compaction.
30 Ib (0.13 kN) minimum weight; consider-
able range is tolerable, depending on
materials and conditions.
Wide variety of rubber tire
compaction equipment Is available;
for cohesive soils, light-wheel
loads such as provided by wobble-
wheel equipment, may be substitut-
ed for heavy-wheel load if lift
coheslonless soils, large-size
tires are desirable to avoid shear
and rutting .
3-wheel rollers obtainable In wide
rollers are available 1n the range
of 1 - 20 tons (8.9 - 178 kN)
weight; 3-axle tandem rollers are
generally used 1n the range of 10
to 20 tons (89 - 178 kN) weight;
very heavy rollers are used for
proof rolling of subgrade or base
course.
Vibrating pads or plates are
available, hand-propelled or
self-propelled, single or in
gangs, with width of coverage from
1.5 - 15 ft (0.45 - 4.57 m) ;
various types of vlbratlng-drum
equipment should be considered for
compaction in large areas.
Tractor weight up to 60,000 Ib.
Heights up to 250 Ib (1.11 kN);
foot diameter 4 to 10 In. (1.57 -
3.93 on).
"acoates and la
167
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The types of equipment in general use for gross compaction include sheepsfoot
rollers, rubber tired rollers, smooth wheeled rollers, crawler tractors and
tampers. Vibrating baseplate rollers, power tampers (or rammers) and manual
tampers (or rammers) are used for fine finishing work both in the base and
sidewalls. (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, inflow/outflow/overflow structures and
specialized supporting structures).
Compaction equipment can be selected based upon weight and transmitted energy
requirements. For non-cohesive 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.
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 two types of vehicles used to add water to soil prior to compac-
tion.
5.2.5 Quality Control
Considering the extensive area of waste disposal sites (tens or hundreds
of acres) and the need to generate a highly uniform soil blanket, the task of
testing "representative" samples is important. It is essential to establish a
statistically sound approach to sampling and testing. This will lead to the
best return of information per dollar. In many situations, sampling from
deliberately chosen spots where it is suspected that the earth work does not
comply with the work requirements reveals an important characteristic of the
work accomplished, that is, the relationship between the operationally stated
requirements (which presumably were not fully observed) and the performance
characteristics. In dealing with the problem of sampling and testing, the
naturally existing heterogeneity has to be scaled. Failure to consider two
basic groups of factors can result in the preparation of a soil liner of poor
quality, e.g. the heterogeneity of the undisturbed soil cover and unjustified
changes in working procedures for a particular soil unit.
5.2.6 Construction of Bentonite-Clay Liner
There are several methods available for the application of a bentonite clay
lining. It can be used as a 1 or 2 inch thick membrane covered with 8 to 12
168
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Figure 5-9 Typical compaction equipment,
169
-------
Figure 5-10. Water vehicle used to prepare the soil for compaction.
inches of earth or gravel (to protect the clay liner from erosion or mechan-
ical damage) or it may be mixed in with the soil to form a uniform surface
layer. The application rate for the latter is about one lb/ft
-------
5.3.2 Soil Cement and Portland Cement Concretes
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 a well graded sandy soil (maximum size 3/4 in) is mixed with the
cement. Type V sulfate-resistant cement is recommended. The design mix
should be tested by the moisture-density relations test ASTM D558, wet-dry
test ASTM 0559, freeze-thaw test ASTM D 560 and the permeability tests of E-13
in the Bureau of Reclamation Earth Manual.
Soil cement is placed using road paving methods and equipment. It should not
be placed in air temperatures 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 7 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 from consulting engineers in this
field. However, some considerations and procedures are presented below.
Subgrade preparation is particularly important if there is a possibility of
high hydraulic pressures against the liner. A layer of gravel or drainage
system should be placed beneath the liner. The subgrade should be well
moistened just before placing the concrete. This will help prevent the
liner from drying too quickly (Bureau of Reclamation, 1963).
Concrete mixes for pond liners 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 for a liner 2-1/2 inches thick or less.
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 not 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
171
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Placing machine is custom built to handle 10.000 cu yd of soil-cement a day.
Conveyor boom extends 100-ft to dump soil-cement mix that is .
compacted by rollers in stepped lifts of 9-in.
Figure 5-11.
Steps in the installation of a soil-cement liner (Brown and
Root, Inc., 1978).
172
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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. The mix does not need the
very high stability of paving asphalt 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 6 inches
to at least 95% of maximum density by ASTM D 1557. 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 (Figure 5-12). 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.
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~i, 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).
5.3.5 Asphalt Panels
Prefabricated asphalt panels require careful planning and workmanship for
Proper installation. The placement and bonding of the panels should be
carefully planned before installation begins. Figure 5-13 shows the instal-
lation of asphalt panels in a small canal. The subgrade is excavated,
smoothed, rolled and soil applied if necessary. Panels are then placed either
butted together or overlapped. Bonding is done with hot or cold asphalt
mastic adhesives. Cold adhesives require more time for construction and
bonding than do hot adhesives which require on-site heating equipment.
The surface to be bonded must be clean and dry. If the panels are butted
173
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^
Asphalt Concrete May Be Applied By Conventional
Paving Machine If Slopes Are Not Too Steep
Figure 5-12.
Placing of hydraulic asphalt concrete liner. Asphalt concrete
may be applied by conventional paving machine if slopes are not
too steep, as shown in the top photograph (Asphalt Institute,
1966). The lower photograph shows a canal being lined by use
of a winch-drawn screed operating transversely up a side
slope (Bureau of Reclamation, 1963).
174
-------
Figure 5-13
Installation of asphalt panel linings in canals. The top
photograph shows the placing of lightweight, buried, glass-
fiber-reinforced, prefabricated lining and the bottom photo-
graph shows the installation of exposed prefabricated lining
(Bureau of Reclamation, 1963).
175
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together batten strips must be cemented over the joints (Asphalt Institute,
MS-12, 1976).
5.4 Design and Construction of Flexible Membrane Liner 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) are conducting 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
ongoing 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. It 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 satis-
factorily. Inadequate subgrade support accounts for many of the failures of
liner installations.
Equally critical to a good project is the proper installation of the selected
liner material over the subgrade. Installation involves numerous steps and
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 impoundment 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 situ1 soils should be determined. The soils may be tested for Atter-
berg 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/swell1 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 sidewalls/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 soil 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 linger, 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 back1
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
liner 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 tne s°il 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. 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 the larger particles by hand raking or grading at
least 3 inches to 6 inches below the desired bottom elevation, and subse-
quently 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.
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 1s 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. This zone should be provided with a carefully designed earth cover
which takes into account the hydrodynamics of the wave action. Experience
with earth dam design has provided us with a good source of practical design
solutions for this problem (Bureau of Reclamation, 1973).
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5.4.2.6 Drainage Consideration
Surface runoff will be affected by the impoundment. If the impoundment is in
the pathway of natural drainage, the diversion drainage systems, overflow
structures and later subterranean diversion systems must be planned to handle
the water excesses in order to minimize potential damage to the impoundment
structure and minimize other adverse impacts. An underdrain system may be
required to remove groundwater which accumulates beneath the installed liner
through time. Infiltrating water beneath liners/impoundments is particularly
common in areas with high subsurface flow, or high groundwater table; the
problem must be recognized in advance so that design accommodations can be
made if the integrity of the impoundment/liner is to be maintained throughout
its projected life. Areas subject to flooding and areas with high water tables
must receive special design, construction, operations and maintenance concern.
5.4.2.7 Impoundment Dimensions
The most economical shape for an impoundment is rectangular with straight
sides. Curved sides and irregular shapes usually add to the grading and
installation costs and increase the number of structural failure points that
can occur. 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. Winds
adversely affect the liner in two principal ways, in the 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).
5.1.2.9 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.
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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.
Where certain woody vegetation or grasses are evident, soil sterilization with
an appropriate heribicide may be required to prevent damage to the liner.
Salt grass, nut 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 sterilization should also be automatically included in the
construction process. If 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 which 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 top width is ten feet in order to allow sufficient room
for equipment 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.
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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 background 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
for early discovery of leaking material, and the environmental sensitivity of
the local system (EPA-OSW, 1977).
Some hazardous substances to be stored in lined impoundments are potentially
so damaging that the regulatory agency may require a leak detection system be
installed immediately beneath the impoundment. The system will usually involve
two liners; an underliner of clay or other suitable material will be overlain
with one to three feet of permeable material. The underliner will slope toward
a center low spot either at a point or along a trench which extends the length
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.
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 verifiable results (probably through
coupon testing and evaluation and periodic groundwater monitoring). Ideally,
the monitoring of liner performance should be in 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.
5.4.2.16 Membrane Liner Coupons
A valuable element of a membrane lined waste impoundment facility is a coupon
placement, testing and evaluation program to reveal the condition of the liner
and the effects of the wastes on liner physical properties over time. The
planning and design process must detail the coupon program. A more compre-
hensive 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
other. Generally, a fill subgrade is built up in a series of compacted
layers, whereas an excavated subgrade is compacted only at its surface.
Usually, the minimum compaction of the subgrade material will be specified.
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Most liner installations require the density of the subgrade achieve at least
a specified percentage of that obtainable by the Standard Proctor Test, ASTM
D698, 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 liner industry, there is a difference of opinion as to how
smooth surfaces must 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 aspect of subgrade preparation. Depending on
the design specifications, various 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. 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.
The control of unwanted grasses and other types of vegetation is accomplished
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
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'
pigure 5-14
Photographs showing various stages of subgrade finishing
subgrades require further work.
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Figure 5-15. Scraper and roller being used to fine finish a subgrade
Figure 5-16.
Representative subgrade surface texture prior to placement of a
flexible liner.
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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
as 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 mil membrane liner. When applying
herbicides, proper protection against inhalation and skin contact should be
taken.
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
should be as soon after completion of 'finishing1 as possible to ensure that
no surfaces are "lost" to the erosive effects of surface runoff.
Figure 5-17. Salt grass penetrating a 30 mil flexible liner,
ization is important prior to placing a liner.
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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
A comprehensive quality control program during design and construction is
a vital element in the planning, design, and construction, and operation.
This program is necesary to assure that the materials used will meet facility
requirements and demands, and that workmanship conforms to the installation
specifications. A quality control program will provide the operator and owner
with confidence that the facility was constructed as planned 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 construction for observation, inspec-
tion and testing of subgrade, liner material, factory and field seam
quality, installation workmanship, and assurance that the design is
followed. Daily records must be 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.
A representative of the primary facility operator, or representative of the
ultimate owner of a lined facility, is usually assigned as the quality control
agent or enginer on liner installations. The agent will be required to assure
that the contractural obligations of the installing contractor(s) are met and
that the installation specifications are fully met. Personnel reviewing the
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design or performing quality control functions for a liner installation should
be familiar with the liner manufacturer's recommendations 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.
5.4.5.1 Subgrade
A quality control plan for the earthwork portion of the project serves two
important functions. First, a uniform density is attained which assures both
owner and engineer that the project is constructed as desinged. Second, it
provides the data necessary to control costs when field densities are higher
than required: this eliminates the possibility of an increased volume of
earthwork (Small, 1980). A quality control program should specify the test
frequency to ensure accurate and reliable field density data and be tailored
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 fill 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
nas 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 needed1 basis.
jn 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 Membrane Liner
The success or failure of the liner installation will depend to a great extent
upon the installing contractor's seam credibility. The three basic require-
ments for credible seam production by heat-sealing are heat, pressure, and
dwell time. 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; and
9. The cleanliness of the seam interface, i.e. the amount of airborne
dust and debris present.
In the case of the adhesive system, the adhesive takes the place of the heat.
However, sufficient pressure and dwell time must be applied to create perm-
anent bonding of the seam interface.
Seaming methods differ between liner materials. Cured materials or vulcanized
materials such as EPDM and Neoprene are usually sealed with a tongue and
groove type seam using gum tape or a two part system. Uncured or unvulcanized
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. Once the
seam has been completed, it should be allowed to stand long enough to develop
full strength. 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. 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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5.4.5.3 Penetrations
Penetrations of a membrane liner are a significant concern with respect to
adequate sealing between the liner and the penetration. 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, spray-on, and other membrane
liners for two principal reasons:
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.
It must be recognized that most membrane materials have relatively little
structural strength and some are quite sensitive to such environmental condi-
tions as sunlight, heat, ozone, and wind. Some therefore may need cover
protection but also care must be taken in selecting and placing a cover on the
membrane liner. In service a liner can be exposed to:
- 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 of lagoon.
- Oxygen and ozone.
- Freeze and thaw.
- Hail and rain.
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- Animals - hoofed, gnawing, etc.
- Vandalism.
Principal reasons for protection include:
a. To protect the liner from sunlight degradation
b. To prevent hail or wind damage.
c. To prevent liner flotation.
d. To protect the liner from mechanical damage during placement of solid
waste or post-construction maintenance.
e. To prevent damage due to vandalism and animals.
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.
Typically, the need for a soil layer as a protective cover is a function of
several variables:
- Composition and properties of the liner material.
- Service environment, e.g. exposure, temperature, etc.
- Weather conditions.
- The characteristics of the waste to be contained.
- The planned degree of protection against animals and vandalism.
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
membranes are susceptible to sun aging if not properly compounded. Thus, the
function of a cover in this case is to block out the sun and prevent sun
aging.
In addition, a cover is necessary wherever vehicular traffic is anticipated
over the liner. In the case of waste impoundment facilities in which hot
fluids are introduced, the cover acts to protect the liner from the initial
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high heat factor and subsequently to insulate the liner from residual heat by
decreasing the temperature at the liquid/liner interface versus the tempera-
ture of the fluid body. In the case of a lined wastewater treatment
impoundment where mechanical 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 or compensating in the design. 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 liner.
Other weather conditions often dictate the necessity for special design or
performance features. Hail can cause failure of some exposed liner materials,
particularly on flat berms where 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 function to reduce the impact of a chemically
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 the 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 the 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
only requirements of a cover material are that it must be free of sharp stone
and other objects and that it not be incompatible or reactive with any waste
that is to De placed on it. The cover material should be stable and resist
sloughing from wave action, not contain large or sharp material which could
nuncture or damage the lining, and should, wherever possible, be local
material to keep the cost low.
Figure 5-18 shows examples of the placing of soil covers on membrane liners.
191
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*
I^BV^HHB9M5W
-
Figure 5-18
Two photographs showing bulldozers applying a soil cover over
membrane liners.
192
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5.4.7. Coupon Testing and Evaluation
A critical component of the design, construction, and operation of a membrane
lined waste impoundment facility is a coupon placement, testing, and evalua-
tion program. The coupon, a separate small piece of the installed liner,
preferably one square foot in area or larger, is used to evaluate the effects
of the wastes on the liner material properties over time. To accomplish this
testing and evaluation program, the placement of the coupons is an important
procedure. Coupon placement should allow for essentially the same exposure
and environment to the waste as the installed liner, safe and easy access and
retrievability, economical placement, precise location, and precise identif-
ication. Thus, the design phase of a lined impoundment facility can con-
tribute greatly to the overall success or failure of a coupon testing and
evaluation program. During the construction phase, the accessibility and
retrievability 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 impoundment, the coupon program will periodically yield
information relating to the physical and chemical integrity of the liner on
which decisions concerning liner replacement 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
proximity of the water table to the 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
which 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 2.5% and the liner must be 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 1 foot down from the
crown of the dike. A simplified representation of a gas vent for membrane
liners is illustrated in Figure 5-19.
193
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12" TO 18" 12"TO18*
AIR-GAS VENT
Figure 5-19. A simplified representation of a gas vent for membrane liners.
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 subgrade is dragged and rolled to produce a smooth surface
free from rough, irregular or angular protuberances. If the surface cannot
meet the above criterion, a fine sand or soil padding may be necessary for
proper membrane support. The site should 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 membrane (Bureau of Reclamation,
1963, p. 80).
Sprayed-on catalytically-blown asphalt membranes are heated to 200-22CTC
(392-428°F) and applied at a rate of 1.5 gal/yd2 measured at 60°F. The high
softening point asphalt should not be overheated since this may lower the
softening point and change other properties of the material. The spray bar is
usually set off to the side of the distributor so that the heavy equipment
does not travel over the subgrade or newly applied membrane. To eliminate
pinholes, it is recommended that three passes be made at a rate of 0.5 gal/yd2
each for a cumulative application of 1.5 gal/yd2 (Asphalt Institute MS-12,
1976). The final membrane is usually about 1/4 inch thick. Sections of
membrane should be overlapped 1 to 2 feet. The newly applied hot asphalt
melts the underlying layer; both cool to form one continuous liner. The
asphalt cools quickly and the next pass with the spray bar may be made immed-
iately after finishing the previous layer. Care should be taken to avoid the
accumulation of sand, silt, dust, or gravel on the asphalt between applica-
194
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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).
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 the emulsion breaks and the water evaporates.
Several light applications are used, not only to avoid pinholes, but to allow
drying between coats to avoid porosity due to entrapped water.
Asphalt membranes are usually covered to protect them from mechanical damage.
Cover materials are usually earth or graded earth and gravel. Membrane damage
and leaks can occur from poor application or choice of cover material.
Blading the cover frequently folds the top of the membrane and should be
avoided. Rocks can tear or gouge the liner. Cover materials should not be
applied if the temperature is below 32°F since the membrane may rupture from
the operation (Day, 1970). Placement of a fine grained soil cover by drag-
lines should be done on the floor first then from bottom to top of the side
slopes. Coarser materials may then be appllied. (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 those 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 Waste Landfill
5.6.1 Environment of the Liner in a Sanitary Landfill
The environment in which a liner must function will ultimately determine how
wel! it can serve for long periods of time. The situation of a liner in a
sanitary landfill is represented schematically in Figure 5-20. Some of the
conditions at the base of a landfill should have 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
195
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LEACHATE
CSU. MCI&HT
LEACHATE
PRAIN
LINER
BARRIER
O-EAN SOIL
Figure 5-20 Schematic drawing of a lined sanitary landfill (Haxo, 1976).
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, land compacted and is presumably free of rocks,
stumps, etc., but that may settle to cause cracking of hard liners.
A brittle or weak material might fall.
2. Anaerobic condition with no oxygen to cause oxidative degradation.
3. No light, which normally degrades many polymeric materials.
4. Generally wet-humid conditions, particularly if leachate is being
generated regularly, that could result in the leaching of ingredients
from a liner.
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 permeability.
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.
196
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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.
5.6.2 Estimating Leachate Volume
The volume of leachate produced at a landfill site is primarily a function of
the amount of water that flows through the refuse; in general, the more
that flows through the refuse, the more pollutants will be leached out.
Precipitation is a key factor affecting the volume of leachate produced;
thus, in regions of moderate-to-heavy rainfall, leachate generation can be
significant. For the designer of landfill leachate collection systems,
however, a qualitative assessment that "significant leachate will be produced
at this site" is not sufficient. What is needed, rather, is a tool for
predicting with a reasonable degree of accuracy the quantity of leachate
that a given landfill can be expected to produce under a number of different
scenarios. Fortunately, within the last several years, such a tool has
evolved, based on a water balance method developed by Thornthwaite and Mather
(1955) in the soil and water conservation field. A computer model has been
developed to simulate hydrologic characteristics of landfill operations
(Perrier and Gibson, 1980).
The water balance method is a kind of mathematical accounting process which
considers precipitation, evapotranspiration, surface runoff, and soil moisture
storage, all of which have a bearing on the extent to which infiltration can
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 given
set of site conditions will provide the designer with valuable information on
Nhich 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 once
a water balance calculation has been made.
Three factors are of critical importance in a water balance calculation: soil
moisture storage, evapotranspiration and surface water runoff. The first is
critica'l 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 ra'infall and low evapo-
197
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transpiration 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 climatic 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).
TABLE 5-4
MOISTURE CONTENT OF REFUSE3
(Average Values)
Refuse at
Placement
Field capacity
Saturation^
Percent
by
volume
10-20%
20-35%
Equivalent
inches H?0/
ft of refuse
1.8"
3.6"
6.6"
Equivalent
gallons H?0/
yd3 of refuse
30
60
110
aAdapted from: Fenn et al., 1975.
on a 0.4 porosity for refuse.
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.
The second most important variable, eyapotranspiration, 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-
otranspiration, 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 by 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.
198
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The third parameter of major importance is surface runoff, i.e. that portion
of rainfall which will run off the site in lieu of entering the cover soil.
Variables affecting runoff include intensity and duration of rainfall, exist-
ing soil moisture, soil permeability, slopes, and type of vegtative 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 the amount of percolation anticipat-
ed at the given site is as follows:
PERC = P - R/0 - ST - AET
where,
PERC = Percolation, i.e. the liquid that permeates the refuse.
P = Precipitation for which the mean monthly values are typically
used.
R/0 = Surface runoff
ST = Soil moisture storage, i.e. moisture retained in the soil
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 that can have an impact on the
water balance calculations is the presence of frozen ground and/or snow
accumulation. Such a condition reduces the infiltration of the precipitation
during winter months with the net effect on the water 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
199
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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 drainage of the completed landfill
surface). These values provide a rule of thumb for use by the designer in
sizing leachate collection systems.
The major advantage of the water balance method is its flexibility in allowing
for modification of various input variables. This enables designers to
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 5-21 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, leachate generation can be
precluded. As shown in Figure 5-22, surface runoff, soil moisture storage,
and evapotranspiration - 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 more impermeable cover soil, (3) using a thicker and denser cover
soil, (4) utilizing synthetic membranes, (5) adding soil conditioners (chem-
icals, bentonite, etc.) to render the existing cover soil less permeable, and
TABLE 5-5 SUMMARY OF WATER BALANCE CALCULATIONS9
Local
soil
conditions
Cincinnati,
Ohio
Orlando,
Florida
Los Angeles,
California
dSource: Fenn
Clay
Loam
Sandy
Loam
Silty
Loam
et al.,
Percolation,
Precipitation, Surface Percolation maximum
mean annual runoff mean annual, monthly,
cm (in) coefficient cm (in) cm (in)
102.5 (40.4) 0.17
134.2 (52.8) 0.075
37.8 (14.8) 0.15
1975.
21.3 (8.4) 6.6 (2.6)
7.0 (2.76) 2.5 (1)
0 0
200
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(6) implementing a good maintenance program for graded surfaces. Like surface
runoff, potential soil moisture storage can be increased by using thicker cov-
er soil and by employing silt and clay cover. Selecting highly evapotranspir-
ative vegetation that is tolerant to landfill conditions enhances evapotrans-
piration. 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 recom-
mended) .
Figure 21 Percolation through solid waste and natural attenuation of
leachate by the soil environment. (Source: Emcon Associates)
201
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Figure 5-22 . Preclusion of leachate production through use of proper drainage
grades and cover soil (Source: Emcon Associates).
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.
202
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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, evapotrasnpira-
tion, and soil moisture storage, leachate will be produced in the landfill.
This net inflow to the landfill, termed percolation on Figure 5-21, 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
retain in a gravitational field without producing a continuous
percolation (Fenn et al., 1975). Thereafter, percolation into the
accumulate as leachate at the base of the fill or discharge to
groundwater regime beneath the landfill (see Figures 5-23 and 5-24).
downward
fill will
the soil-
PRECIPimiON
EVAPO
Uochoti collection pip.
TO LEACHATE COLLECTION SUMP
Figure 5-23
Accumulation, containment, and collection of landfill leachate
(Source: Emcon Associates).
When percolation occurs in a landfill located within a containment environment
Of natural soil, constructed soil liners, or manufactured membranes, 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
rate of discharge (albeit slow) through the liner, or (2)
discharge to the ground surface. Both
leachate to relieve the hydraulic head.
an
it
unacceptable
threatens to
conditions require the removal of
203
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PRECIPITATION
two-
TRANSPIRATION <,r
Htoder
Hocho!« collection
sump
Figure 5-24
Accumulation, containment , collection and withdrawal of land-
fill leachate showing saturation levels for different conditions
(Source: Emcon Associates).
Figure 5-23 shows leachate saturation lines that would result under condi-
tions of leachate accumulation: (1) no withdrawal (2) withdrawal through waste
fill only. (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 5-25.
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 over the base of the landfill.
Figure 5-26, based on a flow net solution, provides a method of determining
the maximum head that will result in a medium given the permeability, spacing
of leachate collection pipes, and percolation rate 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
204
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PERMEABILITY, POROSITY AND DRAINAGE CHARACTERISTICS OF MATERIALS
ro
O
en
I FLOW; Relatively Impervious \ Poor
i I
1 1
1 1
Good
ri- I
TYPES OF MATERIALS: | | | 1 „, _,_
1 .• . 4.1 1^.1 . f £ * A- \ Ti-,n»nY*iii ' clean wane!.* i _
-10 -9 -8 -7 -6 -5 -4 -3 -2 -1
10( 10 10 10( 10i 10f 101 10. 10. 10. 1 10 1(
Permeability, K, in cm/sec:
a) DRAINAGE CHARACTERISTICS:
b) AVERAGE PERMEABILITY VALUES
FOR VARIOUS MATERIALS:
COEFFICIENT OF PERMEABILITY
TYPE cm/sec ft/day (calc)
very fine sand 5 x, 1.0 10
fine sand 2 x 10 50
concrete sand 2.0 x 10 50
fine to medium sand 5 x 10 150
_1
medium sand 10 250
medium to coarse sand 1.5 x 10 400
gravel and coarse sand 3 x 10 B50
4
clean gravel 10 3.0 x 10
concrete gravel 25 7.0 x 10
c) RANGE OF POROSITY VALUES FOR
VARIOUS MATERIALS:
TYPE Porosity %
clay 45 - 55
sand 35 - 40
gravel 30 - 40
sand and gravel 20 - 35
municipal waste 30 - 40
Figure 5-25. Selected characteristics of soils and waste fills (Cedergren, 1967; Davies and
DeWiest, 1966; Freeze and Cherry, 1979; Sowers, 1979; Todd, 1959).
-------
Uniform infiltration rate • q
1 I 1 I I I I I I I 1 I
Saturation line
(a) Cross section of landfill surface
8 10
ro
O
01
0.01
cr
1 X
1 X 10-
1 X 10"s
1 x 10-e
\
\
1 i
V
\
t I
\
\
S (
\
>1
\
\
0 2
\
\
0 9
\
0
x
1C
\
\
X>
\
\
^
\
^
s
10
5
2
DO
•Droinogt mottrlol
For leachate flow conditions represented
conation pip. in Fi9- a' the following equation approximates
the flow net solution:
q = uniform infiltration rate
K = coefficient of permeability
h = head of leachate above
impervious liner
b = width of area contributing
to leachate collection pipe
WHERE:
EXAMPLE 1.
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
from chart; b/h = 20; therefore, the
head (h) acting on the liner = 5'
EXAMPLE 2.
For a I1 thickness of permeable material
overlying soil liner:
q = 2"/month = .O0548'/day
K (sand) = 2 x 10 cm/sec = 50'/day
b = 100'and q/fc = 1 x 10
From chart, b/h = 100; therefore, the
head (h) acting on the liner - I1
b/h
(b) Uniform Infiltration rates vs. b/h for drainage material
Figure 5-26. Determination of leachate head on impervious liners using flow net solution
(Cedergren, 1967). Figure (b) is a log-log plot with subdivisions shown on
the right and top of graph.
-------
the withdrawal saturation line. Example calculations are also presented on
Figure 5-26.
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. 5.7.3 Transmissivity). 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.
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 must 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 fluid 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 the 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 space) while also present-
ing transmissibility characteristics necessary to produce flow to the
207
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withdrawal pump at a rate adequate to maintain the gravity flow from the
collection 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.
5.7.5.1 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 waste 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 porosity 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.
The drain rock (1) must be free of fines that could reduce the transmissivity
of the rock, (2) of a sufficiently coarse gradation so it does not enter the
perforations or slots in the withdrawal pipe, (3) nonsoluble in an arid
environment and (4) sufficiently protected from fines entering from adjacent
soil and/or refuse. Satisfactory performance can be expected if the drain
rock gradation and perforation/slotting width selected satisfies the following
I). S. Bureau of Reclamation criterion (1973):
D85 of the drain rock _ ~
Perforation/slot width ~
where D85 is the screen size through which 85% of the drain rock (by
weight) could pass.
Figure V-2 in Appendix V can be used to determine the required sump capacity
or withdrawal rates needed to ensure gravity flow from 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 pipe(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.
5.7.5.2 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
208
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the pipe from construction damage and stresses due to settlement of the fill.
Alternatively, the riser can be installed vertically from the sump. To
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 5-27 and 5-28 respectively.
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 a pleasing
aesthetic appearance. The subject of covers is presented and discussed in
detail in the "Manual for Evaluating Cover for Hazardous Materials", a com-
panion 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 another companion Manual, "Surface Im-
poundment Closure".
Final soil cover-
PVC cap
(or vent)
Concrete cop
10" « 18" trench in slope
(Pill with drain rock)
8" PVC rlier pip*
Perforated interval"
KL
0
— Leacha
>j •*'" '
•- 1 ** f
te collection dram
— Tflo 3' long section* of
8 header pipe,
perforated
P y^
« . . • »*»x
*- 5' mi
_ 15 « 15 min. sump
pigure 5-27,
(Fill with drain rock)
Typical inclined leachate monitoring and removal system (Source
Emcon Associates).
209
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•Final soil cover
•Waste fill
Leachate
collection drain
1
-PVC Cap
L°J
• 8" PVC riser pipe
•Granular material-placed with slip form
or permanent protective casing
Two 5 long sections of
8 header pipe, perforated
Drain rock
77
.,'5 x 15' min.
(Fill with Ar
sump
i in rnr.lr \
- 5 min.
Figure 5-28.
Typical vertical leachate monitoring and removal system (Source:
Emcon Associates).
210
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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. Fourteenth Edition. American Public Health Association,
Washington, DC.
ASCE and Water Pollution Control Federation. 1969. Design and Construction
of Sanitary and Storm Sewers. ASCE Manuals and Reports on Engineering
Practice No. 37. New York. 332 pp.
Amster, K.H. 1977. Modulus of Soil Reaction (E1) Values for Buried Flexible
Pipe REC-ERC-77-1. Bureau of Reclamation, U.S. Department of the Inter-
ior. 58 pp.
The Asphalt Institute. 1966. Asphalt Linings for Waste ponds. (IS-136)
College Park, MD. 10 pp.
The Asphalt Institute. 1976. Asphalt in Hydraulics. (MS-12) College Park,
Md. 65 pp.
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. 1973. Design of Small Dams. 2nd ed. U.S. Government
Printing Office, Washington, DC. 816 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 627 pp.
Burke Rubber Co. 1973-1979. Product Installation Information, San Jose, CA.
Burmister, D.M. 1964. Envrionmental Factors in Soil Compaction. In ASTM
Symposium, Compaction of Soils. ASTM STP 377. pp. 47-66.
Cedergren, H.R. 1967. Seepage, Drainage, and Flow Nets. John Wiley and Sons,
Inc., New York. 534 pp.
211
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Chelapati, C.V. and F.R. Allgood. 1972. Buckling of Cylinders in a Confining
Medium. Soil-Structure Interaction: A Symposium. HRB Record No. 413.
HRB, Washington, DC. pp. 77-78.
Cheremisinoff, N.P., and P.M. Cheremisinoff. 1978. Fiberglass-Reinforced
Plastics Deskbook. Ann Arbor Science Publishers, Inc., Ann Arbor, MI.
328 pp.
Clarke, N.W.B. 1968. Buried Pipelines, A Manual of Structural Design and
Installation. Maclaren and Sons. London. 309 pp.
Coates, D.F. and Y.S. Yu. Eds. 1978. Pit Slope Manual Chapter 9 - Waste
Embankments. CANMET Report 77-1. Canada Center for Mineral and Energy
Technology, Ottawa, Canada. 137 pp.
Davis, S.N., and R.J.M. DeWiest. 1966. Hydrogeology. John Wiley and Sons,
Inc., New York. 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.
Duvel, W.A., R.A. Atwood, W.R. Gallagher, R.G. Knight, and R.J. McLaren. 1979.
FGD Sludge Disposal Manual. FP-977. Electric Power Research Institute,
Palo Alto, CA.
EPA-OSW. 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-OSW. 1978. Hazardous Waste Guidelines and Regulations, (40 CFR Part 250),
Federal Register. December 18, 1978. 43:58946-59028.
EPA-OSW. 1978. Landfill Disposal of Solid Waste, Proposed Guidelines, (40 CFR
Part 241), Federal Register. March 26, 1979. 43:18138-18148.
EPA-OSW. 1978. Proposed Criteria for Classification of Solid Waste Disposal
Facilities. (40 CFR Part 257). Federal Register. February 6, 1978.
43:4842-4955.
EPA-OWS. 1980. Test Methods for Evaluating Solid Waste, Physical/Chemical
Methods. SW-846. U.S. Environmental Protection Agency, Washington,
DC.
EPA-ORD. 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, Ohio. PB 297-686/8BE.
212
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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 DC. 40
pp.
Freeze, R.A., and J.A. Cherry. 1979. Groundwater. Prentice-Hall, Inc. New
Jersey. 29 pp.
Goodrich, B.F. Company. 1973. Flexseal Liners - Manufacturer's Installation
Booklet.
Goodrich, B.F. Company. 1979. Product Information Publications.
Haxo, H.E. 1976. Assessing Synthetic and Admixed Materials for lining
Landfills: In Proceedings of Research Symposium; Gas and Leachate from
Landfills - Formation, Collection, and Treatment. EPA-600/9-76-004.
U.S. Environmental Protection Agency. PB 251-161.
Hildebrand, J.H., and R.L. Scott. 1964. The Solubility of Nonelectrolytes.
Third Edition. Dover Publications, Inc., New York. 488 pp.
Hoeg, K. 1969. Stresses Against Underground Structural- Cylinders. J. Soil
Mechanics and Foundations Division, ASCE. 94 (SM4):833-858. (Paper
6022).
Highway Research Board. 1972. Soil-Structure Interaction: A Symposium. Highway
Research Record No. 413. HRB, 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., New York. 379 pp.
Lambe, T.W. and R.V. Whitman. 1979. Soil Mechanics, SI Version. John Wiley
and Sons, New York. 553 pp.
Luscher, V. 1966. Buckling of Soil-Surrounded Tubes. J. Soil Mechanics and
Foundations Division. ASCE. 92 (SM6):211-228.
McWhorter, D.B., and J.D. Nelson. 1979. Unsaturated Flow Beneath Tailing
Impoundments. Journal of the Geotechnical Engineering Division, ASCE.
105(GT11):1317-1334.
Middlebrooks, E.J., et al. 1978. Wastewater Stabilization Pond Linings,
Special Report 78-28. U.S. Corps of Engineers. Cold Regions Research and
Engineering Laboratory, Hanover, New Hampshire. 116 pp.
Mitchell, J.K. 1956. The Fabric of Natural Clays and its Relation to Engineer-
ing Properties. Proceedings of the Highway Research Board. 35:693-713.
213
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Mitchell, J K. 1964. Panel Discussion. In: ASTM Symposium, Compaction of
Soils. ASTM STP 377. ASTM, Philadelphia, PA. p. 80.
Mourn, J., and I. Rosenquist. 1961. The Mechanical Properties of Montmorilloni-
tic and Illitic Clays Related to the Electrolytes of the Pore Water.
Proceedings of the Fifth International Conference on Soil Mechanics and
Foundation Engineering. 1:263-267.
Perrier, E.R., and A.C. Gibson. 1980. Hydrologic Simulation on Solid Waste
Disposal Sites (HSSWDS). Draft. U.S. Army Engineer Waterways Experiment
Station, Water Resources Engineering Group, Vicksburg, MS. 51 pp.
Plastics Pipe Institute. 1973. Poly (Vinyl Chloride) (PVC) Plastic Piping Design and
Installation, Technical Progress Report. PPI., New York.
Plastics Pipe Institute. 1975. Polyvinyl Chloride Plastic (PVC) Gravity Sewer Piping
Systems. Technical Report PPI-TR25. PPI, New York.
Seed, H.B. and C.K. Chan. 1959. Structure and Strength Characteristics of Compacted
Clays. J. Soil Mechanics and Foundations Division, ASCE. 85(SM5):87-128.
Seed, H.B. J.K. Mitchell, and C.K. Chan. 1960. The Strength of Compacted
Cohesive Soils Research Conference on Shear Strength of Cohesive Soil.
Sponsored by the Soil Mechanics and Foundations Division, ASCE, Univ. of
Colorado, Boulder, CO. 877 pp.
Sherard, J.L., R.J. Woodward, S.G. Gizienski, and W.A. Clevenger. 1963. Earth and
Earth Rock Dams, John Wiley and Sons, New York. 725 pp.
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. PB 80-175086.
Small, D.M. 1980. Establishing Installation Parameters for Rubber Liner
Membranes. Presented at 117th Meeting of the Rubber Division, ACS, Las
Vegas, Nevada.
Sowers, G.F. 1979. Introductory Soil Mechanics and Foundations: Geotechnical
Engineering. 4th ed. MacMillan Publishing Co., Inc., New York. p. 97.
Spangler, M.G., and R.L. Handy. 1973. Soil Engineering. 3rd ed. Int. Educational
Publishers. New York. 748 pp.
Terzaghi, K. 1955. Evaluation of Coefficients of Subgrade Reaction. Geo-
technique, V (4):297-326 pp.
Thornthwaite, C.W., and J.R. Mather. 1955. The Water Balance. Publications
in Climatology, Drexel Institute of Technology, Centerton, NJ. 8(1):104.
214
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Thornthwaite, C.W., and J.R. Mather. 1957. Instructions and Tables for
Computing Potential Evapotranspiration and the Water Balance. Publica-
tions in Climatology, Drexel Institute of Technology, Centerton, NJ.
10(3):185-311.
Thornthwaite, C.W. 1964. Average Climatic Water Balance Data of the Conti-
nents. Publications in Climatology, Drexel Institute of Technology,
Centerton, NJ. 17(3):419-615.
Todd, O.K. 1959. Groundwater Hydrology. John Wiley and Sons, Inc. New York. p.
53.
Uni-Bell. Recommended Practice for the Installation of Polyvinyl Chloride (PVC)
Sewer Pipe. Uni-Bell Plastic Pipe Association. Dallas, TX.
Wood ley, R.M. 1978. How to Select, Install and Prevent Damage to Membrane
Liners Used in Settling Ponds. Pulp and Paper Buyers Guide, 1979.
215
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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 the
performance of the impoundment is to be maintained and the maximum life of
the liner and the design criteria are to be realized. Special measures must
be taken into account in the management of facilities that are lined. It is
necessary:
a. To protect the integrity of the impoundment and of the liner.
b. To monitor the performance of the liner system to determine whether
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 the Impoundment
The two basic type of impoundments to be encountered are:
a. Pits, ponds, and lagoons.
b. Solid waste landfills.
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-OSW, 1978; ASCE, 1976; EPA, 1973) However, in the
case of lined sites, additional information should be incorporated in the
standard operating procedures for the specific disposal facility. The addi-
tional requirements and procedures in the Manual should reflect the specific
type of material and construction that was used. The operations and proced-
ures manual should be prepared by the design, construction, and operations
team and should include, as a minimum, the following:
- Operation and maintenance staff requirements and structure.
- Facility description and design parameters.
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- Emergency shut-down procedures.
- Operation variables and 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 deletions
to procedures.
6.3 Information on the 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 and information should also be obtained. Samples
of the liner material and other components should be retained for possible use
in cases of malfunctioning of the impoundment. A full discussion should be
obtained from the supplier as to the limitations of the liner material. The
material was selected on the basis of its compatibility with the wastes which
it will contain; consequently, deviations in the waste composition from the
anticipated composition should be avoided. Information of this type should be
incorporated into the operating manual and into the operator training program.
6.4 Control of Incoming Waste
As indicated in the previous section, the composition and character of the
waste must be controlled to avoid 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 the types of industries in
217
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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 should be chemically fixed,
mixed with MSW, soil or a suitable dry absorbent so that the resulting mixture
is not free flowing. Drums and other containers of hazardous wastes should be
surrounded by an inert absorbing material to prevent migration of leaked waste
which might damage or penetrate a liner.
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
standard requirements; however, the organic and inorganic constituents that
are aggressive toward liners should also be recorded. The waste should be
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 be
incorporated in the design of the impoundment for the additon of wastes.
Over-the-edge dumping of wastes should be avoided, as should the additon of
hot waste directly on a liner. Various sacrificial covers have been used.
6.5 Monitoring the Performance of the 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-OSW (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 observe 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 of 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 sludges. Care
must be taken during cleaning so as not to damage the liner. Cleaning crews
should be supervised by someone familiar with the liner to assure that
punctures or tears are prevented, or patched if they occur. If sludge is to
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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.
6.7 Condition of Earthwork
In the case of ponds and lagoons, regular inspections should be made of the
embankments and berms. Attention should be given to possible ground move-
ments, cracks, and erosions of the earth. Since an erosion control problem
usually exists when earth is exposed on an embankment slope, preventive
measures should be taken in the design. However, the inspection is still
needed because failure of the earthwork can result in failure of the liner.
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 be 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
basis1 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.
219
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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:
a. The discharge of high-temperature waste liquids onto exposed or
unprotected liners, i.e. liners with no soil cover or with insuf-
ficient standing liquid levels.
b. The passage of any vehicle over any portion of an exposed liner.
c. The discharge of incompatible wastes to the facility.
d. The direct discharge of wastes with high hydraulic energy upon a
liner without adequate provision for energy dissipation.
e. Unauthorized modifications or repairs to the facility.
220
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REFERENCES
ASCE, Solid Waste Management Committee. 1976.
and Reports on Engineering Practice. No. 39.
EPA. 1973. Training Sanitary Landfill Employees.
Protection Agency, Washington, DC. 203 pp.
Sanitary Landfill. Manuals
SW-43c.l. U.S. Environmental
EPA-OSW. 1977. Procedures Manual for Ground Water Monitoring at Solid Waste
Disposal facilities. EPA/530/SW-611. U.S. Environmental Protection
Agency, Washington, DC. 269 pp.
EPA-OSW. 1978. Process Design Manual - Municipal Sludge Landfills. EPA-625/
1-78-010. SW-705. U.S. Environmental Protection Agency, Washington, DC.
269 pp.
221
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CHAPTER 7. LINER COSTS FOR LINED WASTE DISPOSAL FACILITIES
7.1 Introduction
Costs may be an important factor in the ultimate choice of liner material for
a given site. In order to conduct an adequate cost analysis, the preliminary
design criteria for facilities should be set forth. The cost of the liner is
but part of the total cost of the construction of a lined disposal facility.
A number of additional cost items that are affected by the type of liner ma-
terial, e.g. subgrade preparation, are discussed in the following section.
7.2 Capital Cost
The parameters described and discussed in Chapter 3 and Chapter 5 provide the
technical basis for planning, design, construction, and management of waste
impoundment and disposal facilities. Table 7-1 is a listing of the signi-
ficant cost parameters. It is important to note that the parameters of
interest extend from just below the waste impoundment cover to just below the
subgrade.
A short discussion of each item is provided in the following paragraphs. For
those individuals involved in the planning and permitting process, particular
attention should be paid to the variability of each parameter. For example,
the costs of many of the parameters are site specific, such as rough grading
and groundwater monitoring systems.
The cost of materials delivered to the site includes all costs of all ma-
terials not contained within the site itself. Liner costs are presented in
Tables 7-2 and 7-3. Most of the cost data are for 1976 or earlier. Only
limited current data are in the tables; however, they show the large increases
that have occurred during the past several years. The ratios of the costs
shown for 1976 are believed to be satisfactory.
Prior to rough grading, the site should be cleared of all tall grasses, trees,
brush, fences, poles, stubs, rubbish, debris and refuse. Excavation methods
are determined by the scope of the project and the results of the soils
investigation. Obviously, economies of scale can be achieved for larger
projects. Costs should be determined on a component basis, i.e. the cost of a
dozer or front end loader or other moving machinery. For membrane liners, the
surface should be smooth, and free from any fractured rock, and no smooth rock
should be over 1/4" in diameter. If a sand bedding is placed over the excava-
ted surface, the proof-rolling requirement would be the same. If a geotextile
underlay is to be installed the same proof-rolling requirements applies, and a
surface deviation should be less than 0.1 foot across a 10 foot section. This
will be accomplished generally by smooth wheeled or pneumatic tire rollers.
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TABLE 7-1. CAPITAL COST ITEMS RELEVANT TO LINED WASTE
IMPOUNDMENT AND DISPOSAL FACILITIES
Cost of materials delivered to the site
Site preparation:
Rough grading
Subgrade preparation
Compaction
Surface smoothing
Costs associated with installation of liner(s):
Special structures adaptation
Anchoring
Field seaming
Quality control testing
Groundwater monitoring systems, if necessary, only at lining Interface
Soil cover costs
Liner cover costs
Leachate control system, only at interface with lining(s)
Gas control system, only at interface with lining(s)
Fill for the soil liner should be placed in lifts not exceeding the thick-
ness recommended by the geotechnical engineer. Each lift should be compacted
to the recommended percentage of the maximum dry density as determined by
the Standard of Modified Proctor Moisture-Density Relationship. Embankments
should be slightly overfilled and then cut to finish grade. All tolerances
which applied to excavated surfaces also apply to fill. The cost of imported
fill and its placement can contribute substantially to the cost of the
project.
Proof-rolling of subgrades, usually required for membrane liners, is done with
a heavily loaded rubber-tired roller. A soft subgrade condition should be
overexcavated, material removed, and replaced with suitable fill compacted to
required density. This is the final cost of subgrade preparation.
It is important to establish a quality control plan for compaction and mois-
ture control. This serves two important functions. A uniform density is
attained which assures both owner and engineer that the project is constructed
as designed, and it provides the data for cost control when field densities
are higher than required; this eliminates unecessary earthwork. The quality
control program specifies the test frequency to ensure accurate and reliable
223
-------
ro
Material
Butyl rubber
Chlorinated polyethylene (CPE)
Chlorosulfonated polyethylene (CSPE)
Elasticized polyolefin (ELPO)
Ethylene propylene rubber (EPDM)
covered
uncovered
Neoprene (CR)
Polyethylene (PE)
Polyvinyl chloride (PVC)
"Fabric reinforcement, usually nylon or
Nominal
thickness
mils
30
30
30
20
30
30
30
10
20
JO
ool vester s
—
Fabric
reinforcement3
no
yes
no
yes
no
yes
no
yes
yes
no
yes
no
no
no
crim.
11., HHU KUBBtK
1973
mce,
fob
2.25
2.25
1.66
. . .
2.00h
2.07
0.36
.90
1.33
Installed
costc
$/yd2
3.25-4.00
2.43-3.24
2.88-3.06
2.43-3.42
4.41-5.40
0.90-1.44
1.17-2.16
LlNtKb
1977 iQfin
Delivered
costb
$/yd2
2.70-3.15
2.79-3.24
2.70-3.15
2.79-3.24
2.70-3.15
2.79-3.24
1.80
2.70
2.16
. . .
5.00
0.60-0.70
1.11-1.53
1.44-1.89
Installed Installed
cost0 cost0
$/yd2 $/yd2
3.40-3.60 '
3.10-3.50 6.17", e
3.24-3.78
3.10-3.50
3.24-3.78 7.50-8.50f. 9
2.07-2.25
3.42-3.50
2.88
...
5.85-6.75
1.10-1.40'
1.44-1.98
1.80-2.45
cost in dollars per square yard; cost of sheeting in panel - 5000 to 150,000 sq ft
_ cost is highly dependent on area being lined.
°45 mil thickness, three ply, one ply polyester scrim
fS^il^MiMISr R*™rd'.Jul> 10. 1980 p. 61, does not include subgrade preparation of soil cover
'45 mil thickness, five ply, two ply polyester scrim.
Winning bid, June 11, 1980, City of Seattle, North Beacon Reservoir Reline
"The cost over the range of area of 150,000-500,000 sq ft is usually in the range of $0.05-0.06 per
Soil cover: 1) $.10-.50/yd2/foot of depth
2) .05-.07/ft2/f00t of depth
'If tape is used, tape cost: $0.05-.06/linear foot
square foot.
-------
TABLE 7-3. COST ESTIMATES OF SOIL, ADMIX MATERIALS AND ASPHALT
MEMBRANE LINERS
Installed Cost
Liner type
Dollars per square yard
1973IMJ
Soil + 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
emulsion)
$0.72
1.25
1.25
2.35 - 3.25
3.00 - 4.20
1.50 - 2.00
(with earth cover)
1.26 - 127
5.00 - 7.00
, 1976 (October,1973 costs).
bEstimated installed costs on west coast.
field density data and is tailored to the specific needs and requirements of
the project.
Surface smoothing, the thorough preparation of the finished surface, is a
major ingredient in the success of a lined system. In general the surface
must provide a firm, unyielding and smooth foundation, free of debris of any
kind. The surface should be graded smooth and compacted to finished eleva-
tions in accordance with the recommended tolerances.
/\s discussed previously, it is very important to remove roots and root contam-
inated topsoil. The prepared subgrade should be treated with a reliable
herbicide for this purpose. This subgrade sterilant should be applied in a
uniform manner over the entire site. The cost of application is included with
the cost of the herbicide for the total cost of subgrade sterilization.
The costs for construction/installation of liners is principally associated
with skilled labor. Depending upon the type of liner selected, equipment
rental may be significant. The major cost components are those costs
225
-------
associated with special structures adaptation (penetrations such as inlet
structures, concrete piers or pads, sumps, etc.). anchoring of membrane
liners, field seaming of membrane liners, and quality control testing. The
preceding are affected by weather conditions at the time the tasks are
accomplished and the degree of complexity of each item. As with site prep-
aration, certain economies of scale can be achieved with large projects.
7.3 Annual Cost Items
In addition to the capital costs, there are annual costs of operating and
maintaining a lined disposal facility. The liner type may influence some of
these costs. The annual cost items relating to liner waste impoundments are
listed below:
- Debt service or amortization
- Periodic field checks (surveys) - lining(s), control systems, monitor-
ing system(s)
- Periodic maintenance
- Operation costs
7.4. Case Study Methodology for Analyzing Cost
To facility a deeper understanding, the "case study" analysis methodology has
been selected as the vehicle for estimating costs of lined disposal facilities
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 VII.
226
-------
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 been 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 preferable to another from the
standpoint of impoundment requirements. In making a decision regarding
the selection, it is necessary to consider the liner as a part of a many-
layered system of different permeabilities and characteristics. These layers
extend from the waste itself and the 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 soil liner.
- Review of available 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.
- Reliability of materials, seams, joints, etc. and documented
experience in the technology.
227
-------
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 contain-
ed, whether it be a solid, liquid, sludge, etc. The type of waste will
determine the general type of disposal site, solid waste generally will go
into landfills, and liquid or partially liquid waste will be impounded in
ponds or lagoons. The character of the waste itself should be known as to its
chemical composition and whether there are components present that are highly
aggressive to the various types of lining materials.
The designer should know the anticipated life required of the impoundment. A
landfill liner should last for extended periods of time. Many impoundments
are either evaporating or holding ponds which may require only relatively
short periods of service. The selection of a liner can be greatly affected by
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 Soils on Site
It is important to know whether the soil on site is available from a borrow
pit nearby, whether it can be used as a liner, with or without compaction, or
whether it should be used as a subgrade for other types of lining materials.
From the cost standpoint, soils are generally the least expensive, but they
have a variety of limitations.
In making the decision as to the suitability for the liner, the permeability
to water and to the waste fluid should be determined. Further tests as to the
sensitivity of the soil, such as described in Chapter 4, including testing of
the plastic and liquid limits with water and with waste fluids should be
conducted.
Tests should be made as to the structural strength of the soil. If the soil
does not have adequate permeability or is sensitive to the waste, it still
must be tested to determine 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 soil below the
facility. 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.
228
-------
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
to know the overall geological character 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 up
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
At this point, with the knowledge of the waste that will be impounded and the
level of permeability required in the liner, 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 selec-
tion 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 specific site and the selec-
tion can be based upon costs and other considerations.
8.9 Compatibility Tests
The principal candidates for the liner should be subjected to some tests in
direct contact with the waste. Compatibility tests for soils and membranes
have been suggested in Appendix III. These tests should indicate the
compati bility of the liner to long exposure with the wastes. Incompatible
combinations should become obvious. It is recognized, however, at this
state-of-the-art, that extended lives of many years have not been demonstrated
in actual service; at this point, dependence must be placed on accelerated
testing to assess compatiblity and durability.
8.10 Selection of Liner Material
In making the final selection of a liner material, some factors take prece-
dence over others. The principal function of the liner is to impede the flow
of pollutants from the impoundment for the duration of its required life and
229
-------
sometimes to form the table on which the flow of a leachate can take place for
collection and treatment.
Although there may be some variation in the priority of the factors, the
following requirements must be met:
a. Compatibility and durability of the liner in the presence of the
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 all
met. Following the liner selection, the designer can proceed with the
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.
230
-------
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
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 requirements based upon procedures,
as well as performance.
9.2 Specifications for Construction
In view of the complexity and long times that are required to demonstrate
the performance of a lined waste disposal facility, it is necessary to prepare
detailed specifications for the construction of the facility. Following these
procedures should increase the probability of meeting the project requirements
and assuring an effective waste disposal facility. These specifications
should include specific instructions for the following:
- Site preparation, embankment, and other earthwork.
- Subgrade preparation.
- Liner construction for soils, admixes, sprayed-on materials
- Liner installation, particularly field seaming.
- Quality control - quality assurance.
- Drainage and gas venting systems.
- Appurtenances and penetrations.
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.
231
-------
TABLE 9-1. CONSTRUCTION PROCEDURES AND SPECIFICATION FOR LINERS
OF WASTE DISPOSAL FACILITIES
Preliminary9 List of Suggested References
Liner type
References
.iner
Subqrade and earthwork
Clayey soil
Admix - Asphalt concrete
Soil cement
Bentonite soil
Soil asphalt
Flexible membrane
Spray-on -
Membrane
Asphalt
Modified asphalt
Bureau of Reclamation,
1964, p. 189
Bureau of Reclamation,
1977, pp. 669-700
Day, 1970, pp. 52-60
Asphalt Inst., 1976,
pp. 13-18
Asphalt Inst., 1975,
60 pp.
Day, 1970, pp. 60-64
PCA, 1979
Day, 1970, pp. 64-66
American Colloid Co.
and Dowel 1 Trade
Literature
Day, 1970, pp.46-47
Bureau of Reclamation,
1964, pp.176-184
Day, 1970, pp. 46-47
Asphalt Inst., 1976,
pp. 8-9
Day, 1970, pp. 46-47
Day, 1970, pp. 46-47
American Colloid Co.
and Dowel 1 Trade
Literature
Day, 1970, pp. 64-66 Day, 1970, pp. 46-47
Water and Power,
pp. 4-1 - 4-9
Day,1970, pp. 47-50
Appendix IX
Small, 1980
Manufacturers and
Suppliers Trade Lit-
erature
Asphalt Inst., 1976,
pp. 19-20
Day, 1970, pp. 50-51
Chevron USA, 1978,
pp. 7-9, 13-15
Chevron USA, 1980,
pp. 1-9
Water and Power,
pp. 3-4 - 3-6
Day, 1970, pp. 46-47
Small, 1980
Manufacturers and
Suppliers Trade Lit-
erature
To be expanded in revisions.
232
-------
9.3 Materials Specifications
In addition to the construction specifications, the liner materials must be
controlled and tightly specified. The properties of the various lining
materials are described in Chapter 3 and their installation is described in
Chapter 5.
The range of materials that fall under this 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 come
out of the rubber, plastics and textile techologies and have varied consid-
erably in requirements and in test methods. Even though several test methods
may be used to assess the same property, e.g. tear strength, the specimens,
rates of test, temperatures, etc. have varied. Several organizations setting
standards have prepared specifications on polymeric lining materials such
as:
American Society of Agricultural Engineers (ASAE)
American Society of Civil Engineers (ASCE)
American Society for Testing and Materials (ASTM)
American Water Works Association (AWWA)
National Sanitation Foundation (NSF)
U.S. Bureau of Reclamation
Recently the National Sanitation Foundation and the liner industry have
undertaken to prepare general standards. All segments of the industry,
including raw materials producers, membrane manufacturers, fabricators,
installers, and design engineers are participating by developing concensus
standards. The current drafts of the standards are presented in Appendix
jX. When specifying flexible membrane liners, the tables may provide useful
information but should be used with discretion. The values are preliminary
and subject to change.
These specification tables represent current opinion of the data points to
characterize the membrane product as now on the market and are not proper for
product performance or installation or engineering design criteria per se.
for example, the low temperature resistance numbers represent qualities for a
few minutes at a given temperature and must not be interpreted or extrapolated
into installation temperature qualities or comparisons.
These specifications should not be used to select materials; selection, as
indicated in Chapter 8, should be based upon factors of compatibility,
durability,etc. These specifications should be used as a means of assuring
the quality of the product that will be placed in the waste disposal facility.
233
-------
Liner technology is progressing. The industry is developing new materials and
new products are being introduced. The designer and engineer will incor-
porate these in their designs for lined disposal facilities.
234
-------
REFERENCES
Chapter 9 - Specification for Construction of Lined Waste Impoundments
The Asphalt Institute. 1975. Model Construction Specifications for Asphalt
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.
Bureau of Reclamation. 1964. Earth Manual. 2nd ed. U. S. Government
Printing Office, Washington, D. C. 810 pp.
Bureau of Reclamation. 1977. Design of Small Dams. 2nd ed. Revised re-
print. 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. 1980. Chevron Industrial Membrane for Earthen Reservoirs.
Construction Guide CG-64P. Asphalt Div., Chevron U.S.A., Inc. 9 pp.
Day, M. E. 1970. Brine Disposal Pond Manual. Office of Solid Waste Con-
tract 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: Merritt, F. S.,
ed., Standard Handbook for Civil Engineers. 2nd ed. McGraw Hill Book
Co., New York. pp. 3-1 - 3-23.
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 IS186.02W. Portland Cement Association,
Skokie, IL.
Small, D. M. 1980. Establishing Installation Parameters for Rubber Liner
Membranes. Presented before 117th meeting of Rubber Division, American
Chemical Society, Las Vegas, Nevada.
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, Colorado.
235
-------
CO
CTi
(Exdudinfl panJcJca |«fgcr thin 73mm and bawng fraci.ona on
estimated wcifhia)
Coarse -grained soils
More than hair of maltha
largfr than 75 *m sieve ni
particle visible lo naked eye)
I
"'i the srna
ned soils
material is imallte
sieve lite
he 75 f»m sieve si** is sh
§51 =
m
^j^
1
li,
i t-3
Gravtli
More than half c
rracuon u largi
4-75 mm a»eve
M|.
plf
"Hi
w'3£
Ckan graven
(111 Ik or no
nne*>
Gra veil with
(appreciable
amounl of
and)
r*w«»i aandi
CutUe or no
One*)
f |.
*J33J
i'lP
A |§
ID
i-1'
ill
H!8
« *
HlgtUy Organic Soil*
Wide range In grain liie and lubatutlal
•mount! of all inlenrcaialc partlck
Predominant ly one ilie or a range of lUca
with aoene intermcdnte litct mining
Nonpluilc DOC* (for IdcnilOcatlon pro-
cedure* aee ML below)
Mullc One* (for Identification procedure*
aee CL below)
Wide range In grain liui and lubatantial
amount* of all intermediate particle
•IK*
Predominantly one alze or a range ot nze*
with aome intermediate nzei mining
Nonplaalte one* (for lOcnliOcatlon pro-
cedure*, aee ML below)
Plait ic fine* (for idcmiflcalton procedure*
•ee CL below)
Dry Strength
(cruahing
None to
aHfkl
Medium to
high
Slight to
•otftaaTI
Slight to
medium
High 10
very high
Medium to
high
Dilatancy
(reaction
lo ahaktng)
Quick to
slow
None to
•try lie*
Slow
Slow to
none
None
None to
very slow
*ni aieve aii:
Toughneu
(conintency
near plaiilc
limit)
None
Slight
Slight lo
medium
Hllb
Slight to
Readily Identified by colour, odour.
IDOfXiy feel and frequently by obrou*
texture
Croup
a
aw
Gf
CM
CC
sw
sr
*»
sc
M.
OL
MH
CH
OH
ft
TypicaJ Name«
Well graded gravels, travel-
sand mixtures, link or no
flnei
Poorly graded gravels, gravel-
sand mil tunes, link or no fines
Silly gravels, poorly graded
Clayey gravels, poorly graded
gravcJ-und-clay rruiturxi
Well graded sandi. gravelly
sands, in lie or no fines
Poorly graded sands, gravelly
sands, link or no Ones
Silty sands, poorly graded sand-
uli mliturcs
Clayey sands, poorly graded
Hand-clay mixtures
Inorganic .ills and very fine
sandi. rock flour. nliy or
clayey fine sands with slight
plasticity
Inorganic clays of low 10
cltys. sandy clays, uliy clayi.
lean clays
Orttnic silts and organic sali-
clayi of low pluuoiy
Inorganic tilts, nucaceous or
diitomaceous fine sandy or
silty soils, elastic sills
Inorganic clays of high pl««-
ticity, fat clays
Orsantc clays of medium 10 bitb
ptaiticii;
Peat and other highly oriaaic
tolls
In/ormacion Required For
Describing Soils
Give typical name: indicate ap-
proiimaie percentages of sand
and gravel, mutmum nit. ,
angularity , surface condition.
snd hardncaa of the coarse
graiiu; local or geologic name
and other pcmrveni descnpi.ve
Information; and symboli in
parentheses
For undisturbed soil, add informa-
tion on iiraiincation, degree or
compact neat, ccmeniaiior.,
mo i«i u re condition! and
drainage characiensitcs
bu triple.
Silly sand, grjvclly . jbout 20%
hard, angular gravel par-
n< lea \2 mrn m-mimum size .
rounded and subangularund
grains coane 10 fine, about
15 /; non-plastic fines with
low dry strength, welt com-
pacted and motst in place:
• II u vial und, (SM)
Give typical name: indicate def red
and character of plaiticiiy.
•mount and maximum sue of
coarse grams; colour ui wtt
condition, odour if any. local or
neni dcactiptivc information,
aad lytnbcl In parcnttacsca
For undisturbed soils add infor-
mation oo structure, straiiflca-
lion, consistency in undisturbed
and remoulded nates, moisture
and drainage conditions
Example;
Clayey •///. brown ; iliiAlty
plastic; small percentage of
fine sand; numerous »ertical
root holes: firm and dry m
place; loeis; (ML)
Laboratory Ciaatiflcaitoa
Criteria
I
i
c
^
TJ
£
•O
C
a
c
>
5
|
E
2
|
^>i
1
S
3
W
a
e
1
ii
! .j
t *£
Determine percentagei of giavel and und from g
curve
Depending on percentage or fines 'fraction imallrr
jum sieve siic) coanc grained soils arc classified ai
60
50
H
| 40
?30
£20
10
°,
Ic
Leal than JX CW.cr.SW.Sf
Mc)rtlh«nl2% CM, CC, SM, SC
5% to 12% Bortttrlint casci requiring uae of
dual lymboli
Ul
>- t»
- *a
:I-UL
3 1
rial
lOtnn
{TUMU
JBCM
^0
(.Q..,)'
Not meet
Greater toac 4
1 and ]
ni all gradation requirements for C W
Attcrbcrg linu.i below
"A.1* line, or ft leu
than t
Alter berg limit! abort
"A" line, wiih ft
greater than 7
C0 •
Not
'IT
£>
meet
Great
X L
Above "A" line
wuh Ft between
4 and 7 are
barderiini caaca
rcquinni ujc of
dual symbols
cr Ihan 6
Between
1 and 1
ng all rrsJanoo requirements for SJf
Aiicrbcn limitt belo*
"A" line or f /leu than
5
Aucrbcrt linuu below
"A" line with f/
greater than 7
gall
sal ft
- I pal
( K)Ul
it;fB|
Jlt-lty
' iMJuiJ
U) iftcr
*44f ~
' ^
Cl-| f^ffoi —
Lnii1-!— *—
0 20 30 40 5
Liquic
Plastic!
wratrxy classilica
imm | —
— 1 — f
IM — ' "t
LH -?*-
^
0 6
lim
ty ch
tion
0 71
1
art
3f fin
Above "A" lin«
wub F! between
4 and 7 are
bcrjeriiKg caacs
requiring use of
dual symbols
v;
-DM-
) 3
e gr
7*3=
0 90
amed s
100
of iwo iroupi >re
These procedures iir< to tx perfonTK»i on the minui 380 *im sieve size a
Ottettum (Reaction to shakini):
moisi aoil with a volume of about 8000 mm1. Add enough *a*er°f
necessary to make the soil aoft but not iticky.
Place the pat in the open palm of one hand and shake horizontally, unking
vigoroiialy against the other band several tiroes. A poaltlve reaction
consuls of the appearance of water on the surface of the pat which
changes to • tivcry consistency and becomes glosiy. When the sample
is queued between the fingers, the water and gloaa uiaappcar from the
surface, the pat stiffen* and finally it cracks or cnimbka. The rapidity
of appearance of water during shaking and or ri.uiic
clay of low plaiticity. or material, inch ai kaolitv-typc clays ind orianic
clays »h|Ch occur below the AOiac.
High.y organic clayi have a very weak and ipongy feel at ibe plastic limit.
aoil to the consistency of putty, adding *v* ter if necessary. Allow the
pat to dry completely by oven, sun or air drying, and then ten iti
strength by breaking and crumbling between the fingers Thii
llrenjth is a measure of the character and quantity of the colloidal
fraction contained in the soil. The dry strength increases wuh in-
creasmg plasticity.
High dry strength is characteristic (or clays of the CH group. A typical
inorfmixlc t.li pouc*ac* only very sl.gbt dry stixna.lv Silly fine uitdi
•nd silts have about the tame ih|M dry strength, but can be distinguished
by the reel when powdering th« dried specimen, Fii-« sand reels gritty
whereas a typical silt has the smooth feel of (lour
CO
o :&
1—< -Q
00
on
-------
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
B. BENTONITE PRODUCERS AND SUPPLIERS
C. OTHER LINER MATERIALS
D. MISCELLANEOUS ORGANIZATIONS IN THE LINER INDUSTRY
237
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A. POLYMERIC MEMBRANE LINERS
1. Polymer Producers
DOW CHEMICAL COMPANY
2040 Dow Center
P.O. Box 1847
Midland, MI 48640
Product Sales Manager,
Chlorinated Polyethylene Design-
ed Products Department
Phone: 517-636-1000
E.I. du PONT de NEMOURS AND CO.,
INC.
Elastomer Chemicals Dept.
Wilmington, DE 19898
Contact: Bernard F. Anderson
Phone: 302-774-1000
Contact: Gerald E. Fisher
3707 Chevy Chase Road
Louisville, KY 40218
Phone: 502-459-8752
EXXON CHEMICAL CO.
Elastomer Technology Division
P.O. Box 45
Linden, NJ 07036
Contact:
Phone: 201-474-0100
HERCULES' INCORPORATED
910 Market St.
Wilmington, DE 19899
Contact: Norman C. MacArthur
Phone: 302-575-6293
MONSANTO INDUSTRIAL CHEMICALS CO.
260 Springside Drive
Akron, OH 44313
Contact: Gary E. O'Connor,
Project Manager
Commercial Development
Department
Rubber Chemicals Division
Phone: 216-666-4111
PANTASOTE, INC.
26 Jefferson St.
Passaic, NJ 07055
Contact: Dr. R. Brookman
Phone: 201-777-8500
POLYSAR, LTD.
Technical Development Division
Vidal Street
Sarnia, Ontario
Canada N7T 7M2
Contact:
Phone:
John Red land
519-337-8251
SHELL CHEMICAL COMPANY
605 N. Main Street
Altamont, IL 62411
Contact:
Phone:
Larry Watkins
618-483-6517
UNIROYAL CHEMICAL COMPANY
Spencer Street
Naugatuck, CT 06488
Contact: Allen Crepeau
Phone: 203-723-3825
238
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2. Manufacturers of Polymeric Membrane Sheetings
BURKE RUBBER COMPANY
2250 South Tenth St.
San Jose, CA 95112
Contact: D. Kutnewsky
Manager, Flexible Membranes
Phone: 408-297-3300
GACO
P.O. Box 88698
Seattle, WA 98188
Contact:
Phone:
Earle Johnson
San Jose, CA
415-341-5661
CARLISLE TIRE AND RUBBER CO.
Construction Materials Department
P.O. Box 99
Carlisle, PA 17013
Contact:
Phone:
Hugh Kenney
717-249-1000
COLUMBUS COATED FABRICS
1280 N. Grant St.
Columbus, OH 43216
Contact:
Phone:
Lee Fishbein
614-225-6069
COOLEY, INC.
50 Esten Ave.
Pawtucket, RI
02862
Contact:
Phone:
Paul Eagleston
Vice President
401-724-9000
DUNLINE LIMITED
(A Dunlop Company)
160 Eglinton Aye. E.
Toronto, Ontario
Canada M4P 1G3
Contact:
Phone: 416-487-1114
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 PLASTICS, INC.
5340 Alpha Road Suite 101
Dallas, TX 57520
Contact:
Phone:
Richard K. Schmidt
HART & COMPANY
16 E 34th St.
New York, NY 10016
Contact:
Phone:
R. H. Dickinson
212-48T-1210
KOKOKHU, USA, INC.
P.O. Box 2287
Everret, WA 98203
Contact: Ms. Miki Nakamura
Phone: 806-353-7000
239
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MAINLINE, INC.
3292 South Highway 97
Redmond, OR 97756
Contact:
Phone:
DeWitt Maine
503-548-4207
PANTASOTE, INC.
26 Jefferson St.
Passaic, NJ 07055
Contact:
Dr. R. Brookman
201-777-8500
PLYMOUTH RUBBER COMPANY
104 Revere Street
Canton, MA 02021
Contact:
Phone:
Charles Neese
617-828-0220
REEVES BROS., INC.
Vulcan Coated Fabrics Division
P.O. Box 431
Rutherford, NC 28139
Contact: Walter McEvilly,
Vice President,
Sales and Marketing
Phone: 704-286-9101
SCHLE6EL LINING TECHNOLOGY, INC.
P.O. Box 7730
The Woodlands, TX 77380
Contact: James M. Price, President
Phone: 713-273-3066 (Conroe)
713-350-1813 (Houston)
SHELTER-RITE, INC.
P.O. Box 331
Millersburg, OH 44654
Contact: Dr. Bala Venkataraman,
Vice President,
Research and Development
Phone: 216-674-2015
STAUFFER CHEMICAL CO.
4407 S. Broad St.
Yardville, NJ 08620
Contact: William F. Christie,
Technical Manager
Phone: 201-549-6880
STEVENS ELASTOMERIC & PLASTICS
PRODUCTS, INC.
27 Payson Ave.
Easthampton, MA 01073
Contact: Arnold 6. 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.
Mishawaka, IN 46544
Contact: D. L. Zimmerman
Phone: 219-256-8181
SEAMAN CORP.
P.O. Box 11007
Charlotte, NC 28209
Contact:
Phone:
Jack Watson
240
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3. Fabricators of Liners
BROWN AND BROWN
P.O. Drawer 269
Mobile, AL 36601
Contact: Sam Brown, President
Phone: 205-479-6581
ELECTRA TARP, INC.
Park Centre
7241 whipple 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
FABRICO MANUFACTURING CORP.
1300 West Exchange Avenue
Chicago, IL 60609
Contact: Jay Sabath, Sales Manager
Phone: 312-254-4211
MCKITTRICK MUD CO.
p 0. Box 3343
Bakersfield, CA 93305
PALCO LININGS, INC.
7571 Santa Rita Circle
P.O. Box 919
Stanton, CA 90680
Contact: Richard Cain,
Senior Vice President
Phone: 714-898-0867
POLY-PLASTICS
P.O. Box 299
Springfield, OH
45501
Contact:
phone:
Bill Wheeler, President
805-325-5013
Contact: Roland Harmer, President
Phone: 513-323-4625
PROTECTIVE COATING, INC.
1602 Birchwood Ave.
Ft. Wayne, IN 46803
Contact: Elmo Murrell, President
Phone: 219-422-7503
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
-------
SOUTHWEST CANVAS MFG. CO.
Oklahoma City, OK
Contact: Richard C. Nelson,
Manager
Phone: (405) 672-3355
STAFF INDUSTRIES
240 Chene Street
Detroit, MI 48207
Contact: Charles E. Staff,
President
Phone: (313) 259-1820
(800) 526-1368
WATERSAVER COMPANY, INC
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 Area Sealing Systems, Inc.
SYNFLEX INDUSTRIES, INC.
2004-750 Jervis Street
Vancouver, British Columbia
Canada V6E 2A9
Contact: Gerald W. Salberg,
President
Phone: (604) 682-3621
4. Installing Contractors
CRESTLINE SUPPLY CORP.
2987 South and 300 West
Salt Lake City, UT 84115
Contact:
Phone:
Guy Woodward
801-487-2233
GLOBE LININGS, INC.
1901 East Wardlow Road
Long Beach, CA 90807
Contact: William 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
AL GASTON CONSTRUCTION CO., INC
Gaston Containment Systems
P.O. Box 1157
El Dorado, KS 67042
Contact:
Phone:
John Saens
316-321-5140
GULF SEAL CORPORATION
601 Jefferson
534 Dresser Tower
Houston, TX 77002
Contact: Howard S. Dial, Division
Vice President
Phone: 713-782-9220
242
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MAY ENTERPRISES, INC.
P. 0. Box 6606
Odessa, TX 79760
Contact: Ken Stewart, President
Phone: 915-362-2368
MWM CONTRACTING CORP.
347 North Main Street
Mil ford, MI 48042
Contact: Joe McCullough
Phone: 313-685-9350
313-685-1201
NATIONAL SEAL CO, INC.
7701 East Kellogg
Wichita, KS 67202
Contact:
Phone:
John W. Owen
316-681-1931
PACIFIC LININGS, INC.
P.O. Drawer GGGG
indio, CA 92201
Contact: John Blatt, President
Phone: 714-347-0828
PLASTI-STEEL, INC.
3588 West'13th Street
Vickers-KSB&T Building
Wichita, KS 67203
Contact: M. C. Green, President
Phone: 316-262-6861
SCHLEGEL AREA SYSTEMS, INC
p. 0. Box 23197
Rochester, NY 14692
STA-FLEX CORP.
16 Post Road
Greenland, NH 03840
Contact: Lou Peloquin
4917 New Ramsey Court
San Jose, CA 95136
Phone: 408-224-0604
THE THURSTON WALLACE CO.
5470 East Evans Ave.
Denver, CO 80222
Contact: Hank Thurston, President
Phone: 303-758-2232
TRI STATE CONSTRUCTION
959 108th Avenue, N.E.
Belleview, WA 98004
Contact:
Phone:
Joe Agostino
206-455-2570
Contact:
phone:
James M. Price
716-244-1000
UNIT LINER CO
P. 0. Box 789
Shawnee, OK 74884
Contact: J. A. Hendershot,
President
Phone: 405-275-4600
UNIVERSAL LININGS, INC.
P. 0. Box 315
Haverford, PA 19041
Contact: David M. Small, President
Phone: 215-649-3600
FABRICATORS WHO ALSO INSTALL:
McKittrick Mud
Synflex Industries, Inc.
243
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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:
INTERNATIONAL MINERALS &
CHEMICAL CORP.
IMC FOUNDRY PRODUCTS
17350 Ryan Road
Detroit, MI 48212
Contact:
Phone:
G. Alther
313-368-6000
612-371-3400
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. Box 6504
Houston, TX 77005
Contact:
Phone:
713-972-2670
244
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C. OTHER LINER MATERIALS
THE ASPHALT INSTITUTE
Asphalt Institute Building
College Park, MD 20740
Contact:
Phone: 301-277-2458
CHEVRON, USA, INC.
Asphalt Division
P. 0. Box 7643
San Francisco, CA 94120
Contact: Kenneth Coleman
K. D. 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:
MICHELLE CORPORATION
Division of Weychem Canada Limited
P. 0. Box 4794
Charleston Heights, SC 29405
Contact: F. Weyrich, President
Phone: 803-554-4033
PHILLIPS PETROLEUM COMPANY
Commercial Development Division
Bartlesvilie, OK 74004
Contact:
Phone:
Floyd H. Holland
918-661-6428
PORTLAND CEMENT ASSOCIATION
Old Orchard Road
Skokie, IL 60076
Contact:
Phone 312-066-6200
215-985-660
D. MISCELLANEOUS ORGANIZATIONS IN LINER INDUSTRY
HOVATER-WAY ENGINEERS, INC.
23011 Moulton Parkway, Suite F-5
Laguna Hills, CA 92653
Contact: Louis R. Hovater
phone:
Type of service: Design engine-
ering, specializing in membrane
liners.
LIQUID CONTAINMENT SYSTEMS
P. 0. Box 324
South Holland, IL 60473
Contact: Jack Morel and, President
Phone: 312-468-2500
Type of service: Design, planning,
engineering, and installation of
liners.
LINING MATERIALS
23011 Moulton Parkway, Suite F-4
Laguna Hills, CA 92653
Contact: George J. Miller,
General Manager
phone: 714-581-9292
fype of service: Supplier of a variety
of lining materials.
NATIONAL SANITATION FOUNDATION
NSF Building
Ann Arbor, MI 48105
Contact: Gary W. Sherlaw, Director
Standard Development
Phone: 313-769-8010
Type of service: Developing national
specifications for membrane liners.
245
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SARNAFIL CANADA, LTD.
75 Horner Avenue
Toronto, Ontario, Canada
WATERPROOFING SYSTEMS, INC.
P.O. Box 2182
Santa Barbara, CA 91320
Contact:
Phone:
Ursala Schenck
416-259-9203
Contact:
Phone:
O.E. Hengsen
805-963-6785
Type of service: Developing,
marketing, manufacturing, and
selling membrane liners.
Type of service: Consulting, en-
gineering, and contracting of
various lining materials.
246
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APPENDIX III
SELECTED LINER TEST METHODS
A. IMMERSION TEST OF MEMBRANE LINER MATERIALS FOR COMPATIBILITY WITH WASTES.
B. POUCH TEST FOR PERMEABILITY OF POLYMERIC MEMBRANE LINERS.
C. TUB TEST OF POLYMERIC MEMBRANE LINERS.
D. TEST METHOD FOR THE PERMEABILITY OF COMPACTED CLAY SOILS (CONSTANT ELE-
VATED PRESSURE METHOD).
247
-------
A. IMMERSION TEST OF MEMBRANE LINER MATERIALS
FOR COMPATIBILITY WITH WASTES
Scope;
This test is designed to assess, under accelerated conditions, the compatibil-
ity of polymeric membrane liner materials with specific wastes.
Summary of Method:
Samples of the polymeric liner materials are fully immersed in a represent-
ative sample of the waste to be contained. Over a range of exposure periods,
tests are run to determine the change in weight, dimensions, composition, and
physical properties of the liner material as function of time. One immer-
sion sample is required for each immersion time or exposure condition.
Equipment and Supplies:
Equipment:
- Exposure tank - minimum one gallon or four litre capacity, with provi-
sion for hanging specimens so that they do not touch bottom or sides of
tank, or each other. Suggested arrangements are glass rods across
top of tank, or stainless steel hooks fastened to tank lid.
- Stress-strain machine suitable for measuring tensile strength,tear
resistance and puncture resistance.
- Jig for testing puncture resistance for use with FTMS 101B, Method 2065.
- Oven at 105+2°C.
- Analytical balance.
- Apparatus for running extractables, e.g. Soxhlet extractor or ASTM D297
rubber extraction apparatus. All-glass apparatus is preferred for
chlorinated solvents or for liners which contain chlorine, because
materials containing chlorine sometimes corrode the tin condensers of
the D297 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.
248
-------
Procedure:
1. Obtain representative sample of the waste 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 volatiles (2 h 9 105eC), ASTM D297 (modified).
2.2. Percent extractables with suitable solvent (see Table
III-A-1), ASTM D3421.
2.3. Tear resistance, machine and transverse directions, five
specimens each direction, ASTM D624, Die C.
2.4. Puncture resistance, five specimens, FTMS 101B, Method
2065.
2.5. Tensile tests in two directions, five specimens each direc-
tion, ASTM D412.
- Tensile strength, psi
- Elongation at break, %.
- Tensile set after break, %.
- Stress at 100, 200, and 300% elongation, psi.
2.6. Hardness, Duro A (Duro D if Duro A reading is greater than
80), ASTM D2240.
TABLE III-A-1. SOLVENTS FOR EXTRACTION OF POLYMERIC MEMBRANES
Polymer type Extraction solvent8
Butyl rubber Methyl ethyl ketone
Chlorinated polyethylene (CPE) n-Heptane
Elasticized polyolefin Methyl ethyl ketone
Chlorosulfonated polyethylene (CSPE) Acetone
Neoprene Acetone
Polyester elastomer Methyl ethyl ketone
Polyvinyl chloride 2:1 blend of carbon tetrachloride
and methyl alcohol
a Selected to remove oil, plasticizer, and other soluble constituents
without dissolving the polymer.
3. 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.
249
-------
4. Label the test specimen with a plastic identification tag and hang in
sample of the waste fluid by a wire hanger.
5. 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.
6. To test the immersed sample, remove wire hangers and identification
label from specimen. Wipe off any remaining waste and rinse with
deionized water. Blot specimen dry and measure the following:
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 as
possible to prevent any loss of absorbed water.
7. Perform the following tests on the exposed specimen:
7.1 Percent volatiles (2 h @ 105'C), ASTM D297 (modified).
7.2. Percent extractables, ASTM D3421.
7.3 Tear resistance, machine and transverse directions, two
specimens each direction, ASTM D624, Die C.
7.4. Puncture resistance, two specimens, FTMS 101B, Method 2065.
7.5 Tensile tests, machine and transverse directions, three
specimens each direction, ASTM D412.
- Tensile strength, psi.
- Elongation at break, %.
- Tensile set after break, %.
- Stress at 100, 200, and 300% elongation, psi
7.6 Hardness, Duro A (Duro D if Duro A reading is greater than
80), ASTM D2240.
See Figure III-A-1 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.
10. Fresh waste fluid may be required to maintain concentration of consti-
tuents or to simulate actual service conditions.
250
-------
TEAR RESISTANCE
TEST SPECIMEN
TENSILE DUMBBELL
GRAIN DIRECTION
PUNCTURE RESISTANCE
TEST SPECIMEN
Figure III-A-1. Suggested pattern for cutting test specimens,
251
-------
Test Results:
Examples of the effects of extended immersion of different lining materials
in various wastes are illustrated in Chapter 4 of this Manual.
252
-------
B. POUCH TEST FOR PERMEABILITY OF POLYMERIC MEMBRANE LINERS
This test was designed to measure the permeability of polymeric membrane
materials to water and to various constituents of the wastes.
Summary of Method
Waste is put into a small bag fabricated of the liner material to be tested.
This test bag is placed in a larger plastic bag containing deionized water. A
concentration gradient is thus created across the liner which results in the
movement by osmosis of water and ions and other dissolved constituents through
the membrane. Weight and conductivity measurements are taken periodically to
determine, respectively, the extent of movement of water into the membrane and
the extent to which the waste leaks through the membrane.
Equipment and Supplies
Equipment
- Heat sealer, P.A.C. Bag Sealer Model 12 PI with long interval
timers.
- Clamp made of two 0.5" square steel bars 4" long with 0.25" bolts
and thumb screws located 0.5" from the ends.
- Wooden racks with compartments 1" x 8" x 6.5" deep.
- pH meter.
- Conductivity meter, e.g. Industrial Instruments Conductivity
Bridge Model RC 16B2.
- Balance, 1000 g capacity, accurate to +_ O.lg.
- Stress-strain machine suitable for measuring tensile strength,
tear resistance, and puncture resistance.
- Jig for measuring puncture resistance for use with FTMS 101B,
Method 2065.
- Apparatus for running extractables, e.g. Soxhlet extractor or ASTM
D297 rubber extraction apparatus. All-glass apparatus is preferred
for chlorinated solvents or for liners which contain chlorine,
because materials containing chlorine sometimes corrode the tin
condensers of the D297 apparatus.
Supplies:
- Deionized or distilled water.
253
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- Polybutylene bags with a wall thickness of 6 to 10 mils, and with
dimensions of 8.5" x 10 ".
- Cotton swabs.
- Medium size binder clips.
Procedure:
1. Perform the following tests on unexposed samples of the polymeric
membrane liner materials:
a. Percent volatiles (2 h 0 105°C), ASTM D297 (modified).
b. Percent extractables with suitable solvent (see Table III-B-1),
ASTM D3421.
c. Tear resistance, machine and transverse directions, five spec-
imens each direction, ASTM D624, Die C.
d. Puncture resistance, five specimens, FTMS 101B, Method 2065.
e. Tensile tests, machine and transverse directions, five specimens
each direction, ASTM D412.
- Tensile strength, psi.
- Elongation at break, %.
- Tensile set after break, %.
- Stress at 100, 200, and 300% elongation, psi.
f. Hardness, Duro A (Duro D if Duro A reading is greater than 80),
ASTM D2240.
TABLE III-B-1. SOLVENTS FOR EXTRACTION OF POLYMERIC MEMBRANES
Polymer type Extraction solvent3
Butyl rubber Methyl ethyl ketone
Chlorinated polyethylene (CPE) n-Heptane
Elasticized polyolefin Methyl ethyl ketone
Chlorosulfonated polyethylene (CSPE) Acetone
Neoprene Acetone
Polyester elastomer Methyl ethyl ketone
Polyvinyl chloride 2:1 blend of carbon tetrachloride
and methyl alcohol
a Selected to remove oil, plasticizer, and other soluble constituents,
without dissolving the polymer.
254
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Open for waste
to be added
7"
IT"
II
IL_,
'HI
I
GRAIN
DIRECTION
L.
5y2"-
Figure III-B-1
Pattern for cutting pieces of membrane for making the
bags. Dotted line indicates the heat seal of the bag. The
inside dimension of the bag is 4.5" x 5.75".
2. Cut two pieces of liner as shown in Figure III-B-1.
3. Heat seal the two pieces of liner together leaving the neck open.
Measure the inside dimensions of the bag to the nearest millimeter
and record the calculated area and dry weight of bag.
4. Test the bag for leaks by filling with deionized water. Close the
neck of the bag with binder clips. Weigh the bag and water again
after one week to test for loss by leakage. The emptied bag is then
ready for filling with waste.
5. Measure pH and conductivity of the selected waste.
6. Add one hundred grams of the waste through a funnel. Close the bag
by applying the clamp at the base of the neck. Carefully dry the
inside of the neck with cotton swabs. Heat seal the neck opening.
Remove the clamp, and record the weight of the filled bag.
255
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7. Place the bag in a polybutylene bag with 600 ml of deionized water.
Fold the opening of the polybutylene bag over and secure with binder
clips (Figure III-B-2).
8. Store the assembly in a compartment of the racks so that the sealed
osmotic bag is covered by water in the polybutylene bag (Figure
III-B-3).
9. For testing during exposure, remove the osmotic bag, blot dry, and
weigh. Measure the pH and conductivity of the water in the outer
bag.
10. These measurements should be made weekly during the first month,
bi-monthly during the next five months, decreasing to once a month,
and eventually to once every two months. It is important to watch
for leaking bags.
11. The exposure period should end when the increase in weight and
conductivity have reached a level of constant change or when the bag
material has changed drastically. The expected exposure period is
six months to one year.
12. When a bag has failed or at the end of the exposure period, dismantle
and test by the following procedure:
12.1. Weigh the inner bag.
12.2. Determine pH and conductivity of the water in the outer
bag.
12.3. Measure length and width between seams of osmotic bag.
12.4. Empty osmotic bag and determine pH and conductivity of waste.
12.5. Dismantle bag at seams, leaving bottom seam together.
12.6. Prepare specimens for physical tests. A suggested pattern for
dieing out specimens is shown in Figure III-B-4.
12.7. Perform the following tests:
12.7.1. Percent volatiles (2h @ 105°C), ASTM D297 (modified).
12.7.2. Percent extractables, ASTM D3421.
12.7.3. Tear resistance, machine and transverse direction,
two specimens each direction, ASTM D624, Die C.
12.7.4. Puncture resistance, two specimens, FTMS 101B, Method
2065.
256
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OUTER BAG
POLYBUTYLENE
INNER BAG
MEMBRANE UNDER TEST
LEACHATE OR
Nad SOLUTION
(INSIDE INNER BAG)
DEIONIZEDVYATER
Figure III-B-2.
Schematic of bag assembly, showing inner bag made of membrane
material under test. The inner bag is filled with waste
fluid and sealed at the neck. The outer polybutylene bag,
which can be easily opened, is filled with deionized water.
The water in the outer bag is monitored for pH and conduct-
ivity; the inner bag is monitored for weight change.
13.
12.7.5. Tensile tests, machine and transverse directions,
three specimens each direction, ASTM D412.
Tensile strength, psi.
- Elongation at break, %.
- Tensile set after break, %.
- Stress at 100, 200 and 300% elongation,
psi.
12.7.6. Hardness, Duro A (Duro D if Duro A reading is greater
than 80), ASTM D2240.
The following data should be reported.
13.1. Properties of the unexposed liner materials.
13.2. Properties of liner materials at the end of test.
257
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Figure III-B-3. Bag and auxiliary equipment for determining permeability of
membrane liner materials to water and constituents of waste
fluids.
13.3. Percent retention of properties during the test
13.4. Electrical conductivity as function of time.
13.5. Increase in weight of bag as a function of time
13.6. pH value as a function of time.
Test Results:
Typical test results obtained in the bag test are presented in Chapter 4
258
-------
Figure III-B-4.
Suggested pattern for dieing out test specimens from exposed
bag.
259
-------
C. 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
- Conductivity 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 over
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 IlPC-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.
Tensile strength, elongation at break, modulus, and tear strength of unexposed
liner materials are determined. Physical testing is again performed on the
liner specimens at the end of the exposure period.
260
-------
^^ss^SSS^^^^^^^ssi f::
'n*^^,n\.y v-Kv^-,:•"•;• •.•'•^ii.,v ^' • 'N-'
* 1 . 1
Figure III-C-1. The open exposure tubs lined with polymeric membranes and
partially filled with hazardous wastes.
with chicken wire and placed in a shallow
elasticized polyolefin membrane.
cells are protected by a corrugated plastic cover (Haxo
and White, 1977)
They are covered
basin lined with an
During rainy weather these
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.
/\n 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.
261
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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
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 CPE).
Most of the liners have swelled to some degree after an exposure period of
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 along 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 III-C-1.
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 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.
262
-------
TABLE III-C-1.
FAILED ELASTICIZED POLYOLEFIN LINER
EXPOSED TO SATURATED AND UNSATURATED OILS IN OPEN TUBa
% Retention of property of exposure to
Test
Thickness, mils
Tensile strength, psi
Elongation at break, %
Tensile set, %
S-100, psi
S-200, psi
Puncture resistance, Ib.
Elongation, inches
Original
value
23
2590
665
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
aExposure time: 506 days from 11/2/76 to 3/23/78.
263
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D. TEST METHOD FOR THE PERMEABILITY OF COMPACTED CLAY SOILS
(Constant Elevated Pressure Method)
Introduction
To assess the suitability of compacted clayey soils for the lining of waste
disposal facilities, the primary laboratory measurement is saturated hydraulic
conductivity or permeability. Such a measurement should be made on a specimen
of the soil that has been remolded and compacted in the range of optimum
moisture content to achieve the maximum density possible for a given
compactive effort. ASTM Method D698 should be used for determining a soil
moisture-density relation.
Clays compacted at optimum moisture content have the potential to reach
permeability values as low as 10"^ cm sec. However, permeability values
in the range of 10~5 cm sec~l to 10~8 cm sec'l are more probable.
Testing should be continued until the permeability stabilizes, which may
require the passing of one or more pore volumes of a standard 0.01N CaS04
leachate. For these reasons, it is necessary to use increased pressure to
increase the hydraulic gradient and reduce the time length of the test
(Bennett, 1966). Trapped air is a common cause for artificially low permea-
bility values (Christiansen et al., 1946). An increase of pressure reduces
air trapped in the core by increasing the weight of gas that will dissolve in
water flowing through the specimen (Jones, 1960). The higher pressures will
also reduce the volume of the remaining air pockets. Backpressuring is
necessary in very low permeability soils to dissolve air in the specimens.
The use of deaerated water is desirable.
For a given waste-clay liner combination, there are two fluids that may alter
the permeability of the liner: (1) the fluids present in the waste (primary
leachate) and (2) the fluids generated by water percolating through the waste
(secondary leachate). When only solids are placed in the confinement, only
secondary leachate need be considered. The permeameter used for testing the
influence of leachate on the permeability of the clay liner must be capable of
safely operating with hazardous materials including industrial solvents,
volatile compounds, corrosive acids, and strong bases.
Soil permeability tests must be carefully performed 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).
To avoid channel formation, the clay should be allowed to seat at low pres-
sure. By allowing two to three inches of standard leachate (0.01 N CaS04
or CaCl2) to stand on the core for 24 hours, an effective seat is obtained
for the top few millimeters of the clay core. This thin layer will prevent
bulk flow and the rest of the core should adequately seal when the leachate is
forced into the soil at elevated pressures.
In order to facilitate ease of duplication of the test apparatus, the perme-
ameter is based on readily available and easily modified components. Figure
264
-------
III-D-1 illustrates the modified compaction permeameter which is based on the
standard compaction permeameter that is available through most soil testing
supply houses. All components are in common with the standard permeameter
except for the enlarged fluid chamber, extended studs, and high pressure
fittings.
General Comments:
For use with fluids other than water, all gaskets should be Teflon. To avoid
leakage around the gaskets, all metal surfaces against which the gaskets are
seated should be wiped clean of grit. All components should withstand contin-
uous operation at pressures up to 60 psi.
To limit the volume for diffusive mixing of leachate samples after they have
passed through the clay core, the fluid outlet part should be fitted with an
adapter to a small (1/8 inch) inside diameter Teflon tubing. The use of
translucent Teflon at the permeameter outlet provides a convenient window with
which to monitor the expulsion of entrapped air. Standard leachate should be
passed through the permeameter until there are no air bubbles 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 suspension in
the collected flow samples.
Volatile losses may occur during sample delivery from the outlet tubing to the
sample bottles in the fraction collector. To limit these volatile losses, the
top of each sample collection container should be fitted with a long stem
funnel and the fraction collector should be placed in an air-tight cooled
compartment. This is also desirable where the fluids being tested may present
a health hazard to exposed laboratory personnel.
When volatile hazardous chemicals are used, the entire test apparatus should
be fitted into a vented hood. This precaution is insurance against worker
injury in case of a gasket blow out. If testing of several cores simul-
taneously is desired, each pressure line must have its own cut-off valve to
prevent the complete shut down of the test in the case of loss of pressure in
a single specimen. With several specimens producing leachate, it may be
desirable to have an automatic fraction collector. This is especially useful
with long-term tests. Over the course of a one-month test, it may not be
convenient to change the sample bottles every few hours, twenty four hours a
day.
Calculations;
This test is to determine the intrinsic permeability of a compacted clay by a
constant-elevated pressure head method for the flow of any permeant through
compacted clay soils. The equation applicable to the test is Darcy's law as
modified to normalize permeability values as they are affected by the
permeant1s viscosity and density:
265
-------
— Pressure Intake
S—Pressure Release
I////// / // ///V ^771-Tnp p|ate
N
0
-------
K - V n L
" p g A t (L + H)
K = intrinsic permeability (cm^)
V = volume of flow (cm3) in time t
n = permeant viscosity (dyne sec. cm~2)
p = permeant density (g cm "3)
g = gravitational constant (cm sec'2)
A = cross-sectional area of flow (cm^)
t = time (sec.)
L = length of soil core (cm)
H = pressure (cm of HgO)
The sign is negative to indicate the direction of flow.
Equipment Requirements
1. Soil crusher (C-2 Laboratory Crusher).
2. Soil grinder (Hewitt Soil Grinder).
3. 2 mm sieve (CB-810 brass sieves).
4. Moisture cans (LT-30 tin sample boxes).
5. Balance capable of weighing 20 kgs. (L-500 heavy duty balance)
6. 105"C drying oven 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 sam-
ples over time (Brinkmam Linear II Fraction Collector with a mul-
tiple 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
containing the fraction collector. (This is a safety precaution
to limit exposure of laboratory personnel to the hazardous chemi-
cals 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.
267
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Test Procedure
1. Obtain sufficient clay soil to be tested. Break the soil down to golf
ball size clods and lay them out to air dry.
2. Grind the air dried soil and pass it through a 2 mm sieve.
3. Mix the sieved soil thoroughly, and divide into two lots of equal weight.
Each lot of soil should be placed in air tight containers at room
temperature until the time of use. Each lot should be enough soil to
prepare up to 10 compaction molds (50 kg. will provide for some spillage
losses assuming a mold volume of about 1,000 cm3).
4. Use one lot of the soil to determine the moisture density relations of
the soil by following the ASTM Method D-698.
5. Use a second lot of the soil to prepare compaction molds at optimum
moisture content.
6. Fit a valve on top of the permeameter top plate with pressure fittings
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 go between the
pressure source and regulator to prevent build up of debris on the
membrane in the regulator. The pressure gage should be located between
the regulator and a pressure manifold to the permeameters so that the
hydraulic head being exerted on the clay cores may be monitored.
7. Place sufficient volume of the leaching solution in the chamber above the
compacted soil.
8. Apply pressure to force at least one pore volume of the standard leachate
(0.01 N CaS04 or CaCl) through the clay cores. After the intrinsic
permeability values are stable and less than 10'10 cm2 equivalent to
permeability value of 10~5 cm sec~l at 25°C, release the pressure, disas-
semble the permeameter and examine the core.
9. If the clay core has shrunk, it is unsuitable as a clay liner.
10. If the clay has expanded into the upper mold, remove the excess soil with
a straight edge by cutting so as to not smear the clay surface. Reweigh
the core to determine its density and then remount it on the permeameter.
11. Repressurize the permeameter and pass standard leachate until the intrin-
sic permeability value stabilizes again less than 10'10 cm2 equivalent
to a permeability value of 1.1 x 10'^cm sec~l at 25 C.
12. Remove the remaining standard leachate from eight of the fluid chambers
and replace it on duplicate cores with each of two wastes or waste
leachates to be tested.
268
-------
13. If after passage of one pore volume of the various leachates, the intrin-
sic permeability values of the cores are still above 10'lu cm2, disas-
semble the permeameter and re-examine the cores.
14. If the clay core has shrunk, it is unsuitable as a clay liner for that
waste.
15. If the clay core has expanded, repeat step 10 then proceed to step
17.
16. If the clay has not changed volume, remount it on the parameters.
17. Repressurize the permeameter and pass at least one pore volume of the
standard leachate. If its intrinsic permeability has climbed above
1(H° cm2 (ca. 1.1 x 10'5 cm s~l) the clay is not suitable for containing
the waste. If the intrinsic permeability values measured on a waste's
primary and secondary leachate have consistently stayed below lO'lO
cm2, proceed to Step 18.
18. Examine the translucent Teflon outlet tube for signs of soil particle
migration out of the core. If there is evidence of soil migration, pass
at least one more pore volume to observe if this internal erosion of the
core continues. If it continues after the two pore volumes of standard
leachate have passed, the clay is unsuitable for that waste. If the soil
migration stops, at least one pore volume of the standard leachate should
be passed to assure that the core stabilization is permanent and then
proceed to Step 19.
19. If there is no sign of soil migration, depressurize the system and
extrude the clay cores from their molds to examine them for signs of
cracking, internal erosion, soil piping, clay dissolution, structural
changes, or any other difference from the control cores (those having
received only standard leachate).
If there is no sign that the cores have deteriorated, the clay should be
suitable for lining the disposal facility to contain that waste.
Note: For references, see Chapter 4.
269
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APPENDIX IV
INSTALLATION OF FLEXIBLE POLYMERIC MEMBRANE LINERS
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.
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 equipment
necessary for installation. Figure IV-1 shows liner material packaged
and shipped to the site. Most liner material is packaged in folded panels or
rolls which may weigh from 2,000 to 5,000 pounds each. All membrane liners
should be stored out of sunlight if possible to prevent their degradation
and to minimize blocking. Blocking occurs when the liner material sticks
together, causing delamination or ripping when the roll is unrolled onto the
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 wooden
pallets. The liner material can thus be moved from the storage site to the
construction site by means of a fork-lift truck, or some other suitable piece
of equipment, without damage.
An important consideration in the storage of all 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.
270
-------
Figure IV-1.
Liner panels are shipped to the site on wooden pallets either
rolled or accordion folded.
271
-------
-
.
Figure IV-2. Damage to a fabric reinforced liner caused by "blocking" of the
sheeting. Blocking can occur during shipping or storage when
sheeting is rolled or folded and sticks together under warm
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 if touch up work on subgrade preparation is requir-
ed during installation. A backhoe or front-end loader can also be used to
move sand to the top of the slopes so that sand bags can be filled to prevent
the wind from damaging panels that are placed prior to seaming.
The majority of liner materials are solvent seamed in the field. Hand rollers
are used to obtain a good surface bond. High-density polyethylene is heat-
welded and requires specialized equipment. This includes an automatic welder
which can be raised or lowered along the side slope of the impoundment. A hand
we der is also used. Figure IV-4 shows the hand welder and the automatic
welder being lowered down the side slope by a winch.
For liner materials which require the use of rollers in the field seaming, a
icard at least one inch thick, 12 inches wide, and up to 12 feet long should
be available for each seaming crew to use. This board provides support during
.earning and is placed under the overlap of the liner material. As seaming
progresses, the board is slid along underneath the seam to provide a good
seaming surface. These boards normally have ropes tied to the front so
that they can be pulled along underneath the seam as the seaming crew moves
rom the middle of the panel to the ends. Figure IV-5 shows the rope attached
to a seaming board which is properly located beneath the seam.
272
-------
-w v*
^-^L,'
• t ~ v'.:
>
V 1
4
•*
Figure IV-3.
High-density polyethylene (HOPE) is shipped to the site rolled
onto drums. Each roll may weigh up to five tons.
273
-------
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.
274
-------
board for support under the
pulled along under the line
Figure IV-5. This crew is using a board for support under the area being
seamed. The board is pulled along under the liner with the
rope shown in the picture.
It is necessary to have some means to control the effects of wind on panels
which have been laid on the subgrade. This can be accomplished using old
tires, or more commonly, sandbags placed every five 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 should be used
with extreme caution, as toxic phosgene gas can be formed. Seaming crews
using trichloroethylene should not smoke on the job as inhalation of smoking
materials in the presence of trichloroethylene 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
275
-------
\ *
Figure IV-6.
Sandbags are often used to anchor unseamed
sheets of liner and thus prevent wind damage.
276
-------
Figure IV-7. Heat guns are used to facilitate field seaming
277
-------
other applicators, solvent resistant gloves, safety goggles for men working
with solvents, knee pads, shoes with flat soles to prevent damage to the
liner, scissors and a utility knife, hand-held earth tampers, hand rakes and
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 by
field crews. Wooden dowel rods should be provided to the field crew to use in
moving panels without stretching the edges which will be seamed. These dowel
rods are placed on the edge of the panel; the panel is then rolled onto the
dowel rod. This provides a handle so that the panels can be moved without
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 may 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 the majority of the crew members are
recruited locally, they probably will require 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 number 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
278
-------
TABLE IV-1. EQUIPMENT AND MATERIALS FOR INSTALLATION OF
FLEXIBLE MEMBRANE LINERS
Item
Use
Fork lift
Tires, sandbags
Proper adhesives
Portable electric generator
Air lance
Hand-held earth tampers
Miscellaneous materials:
-Adhesive applicators (paint
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
panels, stakes and chalk line,
steel measuring tape, scissors
and utility knives, electrical
extension cords (for heat guns).
Field crew equipment:
_ Safety goggles, solvent resistant
gloves, knee pads, respirators,
soft soled shoes.
pirst aid kit
Air compressor
To move liner panels and backfill
anchor trenches.
To anchor unseamed panels to prevent
wind damage.
To make field seams and seal liner
around concrete or steel penetrations.
To operate heat guns or lighting for
working at night.
Quality control testing 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.
279
-------
TABLE IV-2. CONSIDERATIONS DURING LINER PLACEMENT
Follow manufacturers' recommended procedures for adhesive system, seam
overlap, and sealing to concrete.
Use a qualified installation contractor having experience with membrane
liner installation, preferably the generic type of liner being installed.
Plan and implement a quality control program which will help insure that
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 be
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) if
skirts are to be used around footings on concrete structures, these must be in
place prior to the beginning of panel placement; (5) any outflow or inflow
structures or other appurtenances should 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 direction,
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 together, sand bags are placed as
shown in Figure IV-11. 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-12). The panels should be pulled
relatively smooth over the subgrade (Figure IV-13). 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-14 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-15 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 that liner material should be question-
ed. Generally three methods are used to seam materials in the field. These
280
-------
Figure IV-8.
The panels of liner membrane are unfolded or
unrolled.
281
-------
Figure IV-9.
Workmen "pull" the panel across the subgrade
difficult to accomplish
282
-------
Figure IV-10.
Once a panel has been unfolded, the crew
"spots" or positions it in the proper location.
283
-------
"
Figure IV-11.
Sandbags are placed along the edges to be
seamed. This prevents wind damage.
284
-------
Figure IV-12
The instructions for unrolling liner panels are
clearly shown on each container.
285
-------
___
Figure IV-13.
Each panel
accommodate
must be pulled smooth, leaving enough slack to
anticipated shrinkage due to temperature changes.
are bodied solvent, heat, or contact adhesive. Solvent and contact adhesive
systems are the most prevalent. The installation contractor should use
the manufacturer's recommended procedure.
The integrity of the field seam is determined by 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 have specified adhesive systems
that work best for their products. These systems normally 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.
Since pressure must be applied to a seam after the adhesive has been applied,
the liner ideally should rest on a dry, hard, and flat surface for rolling
Many installers use a board such as described in Section 2 of this appendix.
This board is placed underneath the overlap of the liner material. Overlaps
can be anywhere from 4 to 12 inches wide, depending on the type of material
and the conditions under which seaming takes place. Once the board is placed
286
-------
Figure IV-14.
Sufficient seam overlap must be maintained.
Manufacturers usually specify minimum overlap
for field seams.
287
-------
%" to 1" SELVAGE EDGE
SEAM
FLEXIBLE MEMBRANE LINER
1/4" to 1" SELVAGE EDGE
BODIED SOLVENT
ADHESIVE
4" to 12"
____,
FLEXIBLE MEMBRANE LINER
Figure IV-15 Typical factory seam (above) 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-16). In the case of some liner materials, e.g. EPDM and CSPE, a surface
cure must be removed with a solvent wash prior to seaming. Field crews should
have suitable gloves to prevent skin reactions from the solvents (Figure
IV-17). Respirators and eye protection may clso be required. Once the surface
cure has been removed, the adhesive can be applied to the liner material.
Figure IV-18 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-19). 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-20). 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.
288
-------
^JL
Figure IV-16.
The surfaces to be seamed must be cleaned to
remove dirt. Cleaning is usually accomplished
with a solvent.
289
-------
Figure IV-17.
Seaming crews working with solvents are advised
to use gloves for protection.
Generally, panels are placed so that field seams will run perpendicular to
the toe of the slopes; that is, the seams will run up and down rather than
along the side slopes. The reinforced materials can be placed so that seams
run horizontally on side slopes. However, a good rule of thumb is always
to place seams vertically on side slopes
panel size or increasing field seaming.
uncured field seams.
where possible without decreasing
This practice minimizes stress on
Installation of liner materials and field seaming during adverse weather
conditions require special considerations with respect to adhesive systems
and temperature limitations. This is particularly true with the thermoplastic
materials since their properties change with temperature. Temperature also
affects the rate that solvents will evaporate and the rate that seams become
strong. Most adhesive systems work best when the temperature of the liner
material itself 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 condi-
tions. Extreme caution must be exercised when using heat guns around flam-
mable solvents, which may ignite, and chlorinated solvents which may generate
the toxic gas, phosgene.
Cold weather seaming requires that the field crew exercise caution 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.
290
-------
Figure IV-18.
Field seaming. Adhesives are applied to the
liner materials.
291
-------
Figure IV-19.
Rolling the seam. After the proper adhesive
has been applied, the seam is rolled smooth.
Depending
n
I
w i no .
upon the location and the weather conditions, the number of panels
6XCeed the number which can be seamed ™ one day.
W6ather conditions occur overnight, unseamed
the subgrade, subject to damage, especially from
will not
wi not
h'
be
i
left
on
IV. 6 Anchoring/Sealing Around Structures/Penetrations
Proper anchoring of the liner around the impoundment perimeter as well as
nscientious tailoring and sealing of the liner around penetrating structures
to satisfactory 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 the trench-and-backf i 1 1 method (Figure
;, anchoring to a concrete structure. The trench-and-backf ill
seems to be recommended most often by liner manufacturers, probably due
292
-------
Pigure IV-20.
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 wrinkle has been rolled smooth and
washed with a solvent; a patch is applied as a final step
(bottom).
293
-------
Trench cut by trenching machine
Insert lining, backfill and compact
1% Slope
12"to 16"
Top of Slope
6"
Minimum
Radius
Linmij
Stable compacted soil or existing concrete,
gunite or asphalt concrete
Figure IV-21
Trench and backfill design for anchoring 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 a 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 can 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 backfilling. These reinforcing rods serve
to hold the liner in place while the seaming is done.
294
-------
The perimeter of the liner may also be anchored to a concrete structure along
the top of the berm or dike. This is usually accomplished with anchor
bolts embedded in the concrete and batten strips composed of a material
resistant to attack by the chemical(s) to be stored in the impoundment.
Concrete that is to come into contact with the liner should have rounded edges
and be smooth and free of all curing compounds to minimize abrasion and
chemical interaction with the liner material. Anchor bolts should be posi-
tioned not more than 12 inches apart on centers. Concrete adhesive is applied
in a strip (minimum width 3-6 inches, depending on the liner material) between
the liner and the concrete where the batten strips will compress the liner to
the concrete. A strip of lining material (chafer strip) may be sandwiched
between the liner and the concrete wherever the liner material contacts an
angle in the concrete structure to prevent abrasion. The batten strips are
positioned over the liner material and secured with washers and nuts to the
anchor bolts. Mastic should be used to effect a seal around the edge of the
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 of
structures may penetrate the liner. These penetrations could include inlet,
outlet, overflow, or mud drain pipes; gas vents; level indicating devices;
emergency spill systems; pipe supports; or aeration systems. Penetrations may
occur in the bottom or through one of the sidewalls, depending upon their
function. Because tailoring and sealing the liner around structures can be
difficult and offers a possibility for failure of the liner, several manufac-
turers recommend that over-the-liner 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 materials and procedures to be used to establish an effective
seal around the various types of penetrations. Proper design of the penetra-
tions and selection of an adhesive material that is compatible with the liner
are important factors to be considered relative to 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-22. 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
295
-------
l_injng / V8"x 1" Short Segments of TL304
Stainless Steel Butt Joined Bars
With Bolt Anchor Studs 6" 0/0 (see note)
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, percussion driven studs
thru 2" min. diameter x %" thick galvanized metal
discs at 6" O/C encased in mastic may be substituted
for anchor shown
Figure IV-22. 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 is 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-23.
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
296
-------
Lining
Lining to Lining Adhesive
Pipe Boot
%" Wide Stainless Steel Band
Metal to Lining Adhesive
4" Wide (see note)
Stable Compacted Substrate-
Concrete, Gunite or Asphalt Concrete
NOTE:
Clean pipe thoroughly at area of
adhesive application
Figure IV-23.
An example of a technique for sealing around penetrations using
the boot type method (Kays, 1977).
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 liner to insure further mechanical stability (Figure IV-24). 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-25). This will help prevent
297
-------
INLET PIPE
HYPALON SHROUD WITH
STAINLESS STEEL CLAMP
30 MIL LINER
BATTEN ANCHOR
SYSTEM
BOLTS ON APPROX.
12" CENTERS
ffl
SEE DETAIL A
CONCRETE PAD
BATTEN:
1. REDWOOD
2. STAINLESS STEEL
3. ALUMINUM
r x v« •
30 MIL LINER A BUTYL TAPE
FASTENER: RED-HEAD
OR RAM-SET
HYPALON
ADHESIVE
INLET SPLASH PAD
NTS
45 MIL
LINER
•CONCRETE PAD
BR 700 CONTACT
ADHESIVE
Figure IV-24. Splash pad construction using a concrete subbase. (Source:
Burke Rubber Company)
damage to the main liner resulting from any abrasive material which might be
present in the water discharged into the facility.
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
fire board 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-26
shows some typical design details for aeration structures.
298
-------
Figure IV-25.
LINER
Sluice type trough constructed of liner material. The easiest
method of placing inlet and outlet pipes into a membrane lined
lagoon is over the top of the berms, using a protective liner
to contain the discharge, thus protecting the main liner. The
fewer protrusions that are designed into a lining, the easier
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 P»0 FOR
FIXED AERATOR
ADDITIONAL LATEK
FLEXSEAL
n / n
;
FLEXSEAL
FOUNDATION
AGDmONAL-
FLEXSIAL LINEN
UNDER PAD
RADIUS ON ALL
Tor CORNCIH
r - CONCRETE MOORING
P-l\ PAD TO MOLD
\FLOATINC AERATOR
I I \ ""
.^.
1 '"
^FLEXSEAL LINEN \V
Figure IV-26. 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.
299
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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 involved are very large and/or the allowable
head build up 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.I Flow Capacity
As indicated in Chapter 5, 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. 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 the 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 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.
300
-------
120 n
c 100-
E
c
_o
1
u
o
O
O
O
o
80-
40-
20-
HT
2
T
3
T
4
T"
5
P«rcolotion, in incha* per month
*Wher« b* width of or»o contributing
to l«ochat« collection pipe
Figure V-l. Required capacity of leachate collection pipe (Source: Emcon
Associates).
301
-------
G P.M. C.F.S.
ro
PIPE' FLOWING FULL
BASED ON MANNING'S EQUATION n=o.oio
0.4 0.5 0.8 0.7 08091 0
K
2 0 3.0 40 50 60 7.08090
Slope of pipe in feet per thousand feet
I
Figure V-2. Sizing of leachate collection pipe (Plastic Pipe Institute, 1975).
-------
V.2 Structural Stability of Pipe
V.2.1 Introduction
Pipes installed at the base of a landfill to collect and conduct leachate to
withdrawal wells can be subjected to high loading of waste fills, which can
rise several hundred feet above the pipe.
Leachate collection pipes beneath landfills generally are installed in one of
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 the
structural stability of a pipe under the imposed loading, the pipe is con-
sidered either a rigid or flexible conduit. Examples of rigid conduits are
concrete and cast iron pipe. Plastic and fiberglass pipes are examples of
flexible pipe. Because the landfill environment is highly corrosive, pipe
materials generally selected for use in leachate control systems are plastic
or fiberglass due to their relatively inert properties with respect to typical
municipal leachate. This section discusses the structural stability of
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 of the total vertical pressure
on the pipe are computed separately and then added to obtain the total vert-
ical pressure acting on the top of the pipe. The refuse fill is assumed to
develop a uniform surcharge pressure, qf, at the base of the refuse. The
magnitude of qf is given by the expression:
qf - («f)(Hf)
where:
qf = vertical pressure at the base of the refuse due to waste fill
(Ibs/sq ft)
o>f = 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:
303
-------
co
o
I I
Soil liner
Watt* fill
q(s(u>f)(Hf)
J_J I
Backfill
a) TRENCH CONDITION
•Liner
V
Backfill (w)
b) PROJECTING CONDITION
Equations for determining the vertical pretture acting on the pipe:
For TRENCH CONDITION:
°v = Bd(uCDt qf CUJ.
Where: C0- -e'2
z KM
W = °V Bc
For PROJECTING CONDITION:
DEFINITIOMS:
°V= ((0,HHf) +0)2,
a> - unit weight of backfill
w,= unit weight of waste fill
H,= height of waste fill
gf= vertical pressure at the bottom of the waste fill
°v = vertical pressure at the top of the pipe
w = force per unit length of pipe
2, = height of backfill above the pipe
Bd= width of trench
BC = outside diameter of pipe
K = lateral pressure coefficient of backfill
fi = coefficient of friction between backfill
and the wal1s
Figure V-3. Pipe installation - conditions and loading (Clarke, 1968).
-------
The term CyS> a load coefficient, is a function of the ratio of the depth
of the trench, I, (measured from the ground surface to the top of the pipe)
to the width of the trench, B
-------
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 Manual of Practice, No. 37. Those values of K y1 representing soils in
which flexible pipes are likely to be installed are:
Type of soil Maximum value of KU'
Sand and gravel 0.165
Saturated top soil 0.150
Clay 0.130
Saturated Clay 0.110
The value of the vertical pressure at the top of the pipe due to the trench
backfill may be determined from the following equation developed by Marston:
*v2 = (Bd)U)(Cd)
where: u> = unit weight of trench backfill (Ibs/cu ft).
The term Cj is a load coefficient which is a function of the ratio Z/Bj
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.
d =
2K
where the terms are as defined above.
The total vertical pressure is equal to:
av = ovi + oV2 = qf CyS
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
306
-------
COEFFICIENT Cd (GRAPH ON LEFT)
J-0 1-52 345
0-K 015 0-200-2503 0-4 0-5 0-607 1-0 1-5
COEFFICIENT Cd (GRAPH ON RIGHT)
i' =0.19, for granular materials without cohesion
B—Q for AX = 0.165 max. for sand and gravel
C—Qfor JSTji' = 0.150 max. for saturated top soil
D-C.I for Aji' = 0.130 ordinary max. for clay
E—C,,for E\i! == 0.110 max. for saturated clay
Values of load coefficient Ca (back fill)
Figure V-5. Trench Condition - Pipe Load Coefficient (Clarke, 1968).
307
-------
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:
°v = (a)f)(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:
(av)design =-1L_ x(o ) t ,
12-lp
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:
Av - n
Ay - u
El + 0.061 E'r3
where:
Ay = horizontal and vertical deflection of the pipe (in)
De = a factor, generally taken at a conservative value of 1.5,
compensating for the lag or time dependent behavior of the
soil/pipe systems (dimensionless)
W = vertical load acting on the pipe per unit of pipe length
(Ib/in)
r = mean radius of the pipe (in)
E = modulus of elasticity of the pipe materials (psi)
E1 = modulus of passive soil resistance (psi) (normally estimated to
be 300 psi for soils of Proctor density of 65%, and 700 psi for
soils of Proctor density of at least 90%)
308
-------
K = bedding constant, reflecting the support the pipe receives from
the bottom of the trench (dimensionless) (a conservative value
generally 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 fraction
of the pipe diameter, Bc, and to relate it to the vertical stress on the pipe
as follows:
W o Uy)(EI + 0.061E'r3)
~~ (Bc)( DeKr3 )•
Solutions to this equation are shown graphically in Fig. V-6 where the quant-
ity ° v/( Ay/Bc) has been plotted against the passive soil modulus E'. The
relationship between °v/(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 represent a
relationship between °v/(Ay/Bc) and E1 if the stiffness of the pipe is
neglected.
In addition to using the chart to check the adequacy of a given pipe, the
chart can be used to determine the necessary value of EI/r3 which the pipe
must have for given values of °max/(Ay/Bc) and E1. Although it is custom-
ary to use either 300 or 700 psi for the value of the modulus of passive soil
resistance, it should be noted that the modulus of elasticity of a coarse
grained soil (sand or gravel) increases with increasing pressure (or depth in
the ground). Thus, it should be expected that the modulus of passive soil
resistance also would increase with increasing pressure or depth of fill.
The term El in Spangler's equation reflects the pipe's contribution to the
total resistance to deflection under load offered by the pipe/soil system.
This term, known as the pipe's Stiffness Factor, is related to the pipe's
behavior under parallel plate loading as per ASTM D 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 (Ib/linear inch) required to produce a pipe
deflection Ay
Ay = the pipe's deflection (in).
309
-------
1300
(200
1100
1000
900
~ 800
in
o.
ffl
700
600
500
400
300
200
100
Assumed: D» = 1.5
K =0.1
Figure V-6. Selection of Pipe Strength
* (ASCE, 1969)
310
-------
Minimum values of the term F/Ay, called Pipe Stiffness, are set according to
Pipe DR (dimension ratio) by the ASTM PVC Sewer Pipe Specifications D 3033 and
D 3034. The DR represents the ratio of the pipe's average outside diameter to
its minimum wall thickness. Thus, for each DR there is a corresponding
minimum specified value of F/Ay.
The above expression for El can be substituted into the previous equation for
deflection to obtain the following:
°v = (0.149F/Ay) + 0.061E1
) DeK
Solutions to this equation can be made on a graph similar to Fig. V-6 where
the quantity °v/(Ay/Bc) 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 pipe to support vertical stresses may
be limited by buckling. Estimates of the vertical stresses at which buckling
of the 6-inch Schedule 40 PVC pipe (the most flexible of the four pipes shown)
will occur are indicated by the curve in Fig. V-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 may be influenced by the
circumferential compressive strength of the pipe. The designer or reviewer
should secure up-to-date information on circumferential compressive strength
characteristics from the manufacturer of the type of pipe proposed for use.
V.2.6 Construction Loadings
A pipe correctly designed to withstand loading from a high fill can fail from
loading received during construction._ Although only a fraction of a station-
ary wheel or tracked vehicle load applied at the ground surface over a trench
is transmitted to a pipe through the trench backfill, the percentage increases
rapidly as the vertical distance between the loaded surface and the top of the
pipe decreases. In addition, moving loads cause impact loading 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 loading can 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.
311
-------
V.2.7 Procedures for Selection of Pipe Strength
The procedures used to select the proper strength pipe are illustrated in the
following examples:
Trench Installation (See Figures V-4 and V-7)
Given: Z = I1-8" Hf = 100 feet waste fill
Bd = I1-6" oif = 50 pcf
Ku' = 0.19 ID = 110 pcf
pipe diameter = 4"
Determine: Required pipe strength/schedule.
Step 1 - Determine the maximum vertical pressure °v (psf) acting on the
top of the pipe.
JL = il^Z. = 1.11 qf = (o)f)Hf = 100 (50)
Bd 1-5 = 5000 psf
from Fig. V-4, CyS = 0.64
Fig. V-5, Cd = 0.9
then; °v = (o))(Bd).(Cd) + (qf)(CpS)
= (110)(1.5)(0.9) + (5000)(0.64)
= 3348 psf = 23.3 psi = Jv max
312
-------
-
L.
— Waste fill
1 — Excavation subgrade
6" mln. — '
y-%1
-*» rvu |
"•'•V
r^y. f° v^
r
.z'-i\
> —
>ipe, perron
r-2'
-Drain rock
-Excavation slope
5'
Waste fill-
Drain rock
6 min.
4 PVC pipe, perforated—'
PROJECTING INSTALLATIONS
Excavation slope
— Waste fill
— 2'-6"
'
_.«
-6
::
,°
r
» •
* P
>•
';-/
6' r
4" PVC DIDO 1
- I1- fi"
X
>erforated
TRENCH INSTALLATION
Figure V-7 Typical Leachate Collection Drains (Source: Emcon Associates)
313
-------
Step 2 - Select the appropriate modulus of passive soil resistance E'
(psi). For gravel bedding use 300 to 700 psi.
Step 3 - Select allowable pipe deflection ratio Ay/Bc. Use 0.05 to
0.1.
Step 4 - Determine the quantity v max where °v max is in psi
VBC
From Fig. V-6 the following information is obtained.
°v max
AY/BC
0.05
0.1
Ay/Bc 300
466 4" Sch 80
adequate
233 4" Sch 40
or
6" Sch 80
adequate
700
4" or 6" Sch 80
adequate
Any pipe
Positive Projecting Installation (See Figures V-3 and V-7)
Given: Z, = 6"; other parameters given as in example above
Determine: Required pipe strength/schedule
Step 1 - Determine the maximum vertical pressure CTv(psf) acting on the
top of the pipe.
oy = «fHf +uZl = (50) (100) + (110)(0.5) = 5055 psf = 35.1 psi = Jv max
Steps 2, 3, and 4 as above
From Fig. V-6 the following will be obtained.
°v max
Ay/Bc Ay/Bc
0.05 702
0.1 351
300
none
acceptable
4" Sch 80
adequate
E1
700
none
acceptable
4" Sch 40
or
6" Sch 80
adequate
Note: See Chapter 5 for References.
314
-------
APPENDIX VI
SWELL BEHAVIOR OF SOILS AND CLAYS
Nayak and Christensen (1971) enumerated eight factors which affect the swell
behavior of a soil. A ninth factor which appears to be relevant in the case
of liners has been added. These nine are:
1. Type and amount of clay mineral.
2. Initial placement conditions e.g. structure, density.
3. Stress history.
4. Nature of pore fluid.
5. Temperature.
6. Volume change permitted during swelling pressure
measurements.
7. Shape, size, and thickness of the sample.
8. Time.
9. Load conditions.
Nayak and Christensen, testing a limited number of samples but covering a wide
spectrum of physical and mineralogical properties, produced a semiempirical
relationship in which the swell is predictable if the plasticity index (PI),
percent clay content (C), and moisture content of the sample (w) are known.
The swelling potential (Sp) for a mixture of sand-grundite-bentonite, is:
Sp = (1.3548 x 10-2) x (pi)1.59 x £ + 4.8046
W
and for a mixture of sand-kaolinite-bentonite is:
Sp = (4.4938 x ID'3) x (PI)l-™ x £ + 14.722
W
Although the use of these kinds of relations is encouraged, one has to be
aware of their limitations. In this particular case, for instance, the
regression equations were calculated using very high swell data, presumably
because of the use of a Na-bentonite. Naturally occurring soils are quite
different.
315
-------
When different specimens of a silty clay soil were compacted at various
combinations of density and moisture content, it was found that, for samples
with the same density just prior to testing for a change of volume, both
shrinkage and swell increased with a decrease in moisture content during
compaction (Seed and Chan, 1959). Consequently, if volume changes are
to be prevented, the compaction operation in the field has to be conducted at
the highest operationally possible moisture content (Holtz and Gibbs, 1956).
The higher the moisture content and the lower the density as compacted, the
safer the above conclusion since, in this range, errors in the moisture
content will result in only slight increases in swell. However, soil liners
cannot be compacted at low densities for other obvious reasons. One should
bear in mind that the higher the density as compacted for the same air-filled
porosity, the larger the underestimation of swell if a certain error is made
in the moisture content of the soil during compaction.
Plotting isoswell curves on a density-moisture content graph, (Figure VI-1),
Holtz and Gibbs (1956) were able to show that (Seed et al., 1962):
a. An increase in molding water content at any given density causes a
decrease in swelling pressure and swell.
b. 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.
The character of an isoswell map on a density-moisture content graph depends,
for any particular soil, on the relative proportion of solid, liquid, and air
phases. Thus, the extreme cases, "maximum swell" and "no swell at all",
should correspond, respectively, to the situations "high solid-low liquid-
low air" and "low solid-high liquid-high air". Different situations can be
integrated by the values of the negative pore-water pressures for the as-
compacted state.
The structural characteristics of the soil cannot be overlooked; indeed, the
value of the pore water pressure measured in a compacted clayey soil has to
reflect, to a large extent, structural differences. As was pointed out by
Seed et al. (1960), the differences in structure generated on 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 comparison to the situation "at rest" when the
particles tended to have a more flocculated arrangement. Consequently, the
statically compacted samples swell more because their flocculated structure
corresponds to lower pore-water pressure, i.e. larger affinities for water.
In the situation relating to clayey soil liners, the volume change tendencies
of the compacted soil liner are relevant only to the extent that they affect
flow properties, if soil strength does not have to be considered. It was
316
-------
jo n so
WATCH CONTENT-XOF DRY WT.
Figure VI-1
Isoswell lines on moisture-density graph;
expansive clays under extremely dry and
dense conditions (Seed et al . , 1962).
recognized some time ago that shrink-swell tendencies are important in the
case in which an "hydraulic" structure such as a soil liner is constructed
(Holtz and Gibbs, 1956).
One of the most often quoted examples in which swell characteristics were
related to flow properties is the one described by Macey (Lutz and Kemper,
1959) in which, for the particular soil used, the ratio Kwater/Knonp0iar_
organic was in tne range 10~^ to 10~6. This small ratio was attributed
to the swelling of the soil when water was the fluid used, compared to the
rigid-structure behavior in the case in which nonpolar organic solution was
the flowing fluid. In most practical situations, the effect would be less
drastic.
In general, it is assumed that swelling is beneficial rather than detrimental,
in the sense that swelling reduces the average pore size (McNeal and Coleman,
1966; Shainberg et al., 1971) and enhances dispersion and, associated with
this, plugging of pores (Hardcastle and Mitchell, 1974; Shainberg et. al.,
1971). It is also possible that a reduction of permeability upon swelling
and dispersion is associated with an alteration in properties of the water in
the vicinity of the matrix wall (Miller and Low, 1963). Situations were
317
-------
described when the pore size distribution of the soil was such that internal
soil erosion was favored by dispersion, with the result of an increase
in permeability (Aitchison and Wood, 1965); this kind of behavior should
be considered an exception in soils with a quasinormal distribution of
different particle size fractions.
As Cardwell stated (Mielenz and King, 1955), swelling and sealing ability of
clays do not match in a perfect manner. He indicated that:
a. All high permeability clays have low swell.
b. All high swelling clays have a low permeability.
c. Some low permeability clays have low swell.
Since, at present, the effect of swell upon soil permeability (although
tending to reduce) cannot be quantified, the soil liner should be designed
for a particular permeability, assuming no beneficial effect will occur due
to saturation and swelling. After all, swelling is a process of bulk volume
increase, i.e. an increase in void ratio and, if no structural changes occur
during water uptake, then the permeability should increase. The basic reason
why this almost never happens is because, during water uptake, soil capillary
forces are partially released which corresponds to a less flocculated struc-
ture. The net bulk volume increase is partially the result of water uptake by
the fines between relatively large silt soil particles which, by this me-
chanism, are pushed farther away from each other.
In assessing the volume change tendencies of a soil which will be compacted
into a soil liner, thixotropic characteristics have to be identified, if
present. Thixotropy is considered to be the most important mechanism which
generates sensitive structures in soils having sensitivity values up to eight
(Mitchell, 1976). Sensitivity is defined as the ratio of the strength of
undisturbed soils to that of the soil remolded. Thixotropic hardening,
associated with a decrease in pore water pressure as a result of a more
flocculated structure, is defined as the increase in strength with time at
constant volume, temperature, and water content. Since changes in structure
due to thixotropic hardening result in a more flocculated structure, one could
predict that when a thixotropic clayey soil is compacted into a soil liner
with a characteristic permeability, in time this value will increase.
Bentonites, which are popular in the area of water management, are highly
thixotropic materials; they harden to gel in short times (Boyes, 1972).
The Na-montmorillonite, typically the main component of the bentonite rock, is
responsible for this behavior. In general, montmorillonitic clays, widely
recognized as perfect soils for water confinement operations because of
their very small particle sizes, swelling, and sealing characteristics, etc.,
have to be looked upon as being potentially troublesome materials; for
this kind of soils, short-term laboratory experiments cannot predict the
long-term field behavior. As an example of such behavior, Kelley observed
the failure of a bentonite pond floor which cracked during operation,
although it was permanently submerged under water (Mielenz and King, 1955).
318
-------
According to Mielenz and King (1955), materials with free swell larger than
600% should be used if an impermeable liner has to be obtained. While this
figure is quite large, it emphasizes the generally found trend that swelling
soils are sealing soils. It seems to us that due to the paucity in quantita-
tive information regarding the volume change-permeability relationship, rather
than counting on the beneficial effect of swell, the designing unit should
make sure that the presence of a swelling soil will not be the cause of an
unwanted behavior.
Note: For references, see Chapter 3.
319
-------
APPENDIX VII
SYSTEM ANALYSIS AND OPTIMIZATION OF SOIL LINER DESIGN
The purpose of the design is to achieve a seepage below the liner, lower than
a certain critical value, qp. The analysis of the system can be done using
different procedures. As an example, we will use the McWhorter and Nelson
(1979) analysis. For convenience, we will preserve the nomenclature used by
the authors. A schematic representation of the flow system is presented in
Figure VII-1.
In the subsequent analysis, it is assumed that the geometry of the system is
unchanged in time, i.e. the depth of the free waste fluid, y, the depth of the
solid waste, D^, and the depth of the underlying undisturbed soil, Df, are
given. The depth of the soil liner D] is variable. The permeability of the
solid waste, Kt, and the permeability of the isotropic, homogeneous underly-
ing soil Kf are also given. The permeability of the soil liner K] is variable
and can be optimized vis-a-vis the depth of the soil liner DI to result in a
seepage rate lower than qp. Other parameters which will be found in the
analysis have the following meaning:
n = soil porosity, equal to volumetric moisture content when the soil is
saturated.
6j = initial volumetric moisture content of the underlying soil.
hd> er> and * = parameters experimentally found when determining the
moisture characteristic curve (MCC). The MCC is the
relation between the magnitude of suction applied and the
equilibrium moisture content corresponding to the given
negative head.
hjj = 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_"C
SATURATED
SOLID WASTE
K = 1C
SOIL LINER
K = K
UNDISTURBED SOIL
K = Kf
PHREATIC
SURFACE
D
x •
AQUIFER
IMPERVIOUS
^,
Figure VII-1. Sketch of the flow system.
H
x = 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 \ = 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.
321
-------
Stage 2 - This stage starts as soon as the wetting front reaches the
groundwater or its capillary fringe and a groundwater mound is being
formed. Stage 2 continues until the mound reaches the base of the
liner.
Stage 3 - Saturated flow throughout the whole system.
It is clear that the slower every stage is developed the better suited the
system is to confine wastes. If, for instance, Stage 3 is reached the success
of the system in control ing contamination will rely heavily on the ability of
different strata (soil liner and underlying soil) to chemically bind the
contaminants. If fresh waste fluid is continually added to the waste disposal
site, the strata will reach their saturation. In the long run the system
sketched in Figure VII-1 will have the same composition and concentration as
the fresh waste fluid. The limiting concentration at a well will be a
fraction of the fresh waste fluid concentration due to dilution by the incom-
ing fresh groundwater stream.
At the present level of knowledge, we have to prevent the occurrence of
Stage 3 and even Stage 2. Accordingly, we will analyze numerically some of
the important parameters during the infiltration towards the groundwater
(Stage 1).
Example of Numerical Analysis for Stage 1
The advancement of the wetting front between the soil liner/underlying soil
interface and the original groundwater level can occur either as a saturated
or as an unsaturated flow, depending on the geometry and flow properties of
the traversed strata. For our purpose, the less saturated the flow the
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 + Dt + Pi) -hf (1)
q Dt Dl
**.. j, _
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(j, i.e. hf < h
-------
Assuming the optimization of the system can be achieved by varying D-J and
KI, 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, hj, is equal to -50 cm equivalent water, equation 2
becomes:
Dt . 10-5 t 50 < ,0-5 . Dl (3)
The values of the left hand side of the inequality expressed in cm, are
presented in Table VII-1 for different y, D^, and K^ levels.
TABLE VI 1-1. LEFT HAND SIDE OF EQUATION 3. in cm
y,
feet
3
60
feet
1
20
1
20
TO'4
169
690
1906
2428
Kt (cm sec'l)
lO-5
141
141
1879
1879
10'6
-133
-5351
1604
-3619
The right hand side of the inequality (Equation 3) expressed in cm, is pre-
sented in Table VII-2, for different combinations of Iq and DI, the perm-
eability and the depth of the soil liner.
TABLE VII-2. RIGHT HAND SIDE OF EQUATION 3, in cm.
Kl,
cm sec"1
10'5
10-7
10-8
1
275
3,023
39,500
D!
feet
6
1,678
18,123
182,880
The condition of unsaturated flow hf
-------
In Table VI1-3, we present the system requirements which will generate the
best observance of the condition hf 1500. The same requirements are satisfied by D] = two
feet and a permeability KI = 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 •'
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:
y + Dt - 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 1-4.
324
-------
TABLE VI1-4. LEFT HAND SIDE OF EQUATION 4, in cm
y
feet
3
60
Dt
feet
1
20
1
20
10-4
272
845
2009
2583
Kt (cm sec'1)
10-5
269
790
2006
2528
1Q-6
241
241
1979
1979
The right hand side of Equation 4 is presented in Table VII-5.
TABLE VII-5. RIGHT HAND SIDE OF EQUATION 4, in cm.
Kl 1
cm sec'1
io-6
10-7
10-8
1
0
275
3,020
feet
6
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
Kt/Kf are very low. This can be seen from the 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 this
figure, that the two important properties of the underlying soil are: Kf =
10~5 cm sec~' and h^ = -50 cm equivalent water, the resulting working equation
becomes:
Dt I2'40 ;10'7i - , - Dt - 105.4 . D, - D, j^i^J (6)
The left hand side of Equation 6 can be calculated for different y, D^, and
Kt values. The results expressed in cm, are presented in Table VII-6.
TABLE VI1-6. LEFT HAND SIDE OF EQUATION 6. in cm
y
feet
3
60
Dt
feet
1
20
1
20
10-4
-227
-805
-1965
-2542
Kt (cm sec'1)
lO-5
-227
-792
-1964
-2529
10~6
-220
-660
-1957
-2398
The left hand side of Equation 6 and its right side have, for the chosen
parameters, values between -200 and -2600 cm. If two particular values for
the depth of the soil liner DI are considered, one foot and six feet, the
needed permeabilities of the soil liner KT can be calculated. They are
presented in Table VII-7.
TABLE VII-7. SOIL LINER PERMEABILITY KI, REQUIRED
TO RESTRICT THE FLUX AT q = 3"/YEAR, WHEN THE LEFT
HAND SIDE OF EQUATION 6 TAKES VALUES BETWEEN -200
AND -2600, FOR TWO DEPTHS OF THE SOIL LINER, DI .
Left hand side
of Equation 6 feet
-200
-600
-1000
-1400
-1800
-2200
-2600
1
3.2 x 10-8
1.2 x 10-8
7.1 x 10-9
5.1 x 10-9
4.0 x 10-9
3.3 x ID'9
2.8 x 10-9
6
1.1 x 10-7
5.6 x 10-8
3.7 x 10-8
2.8 x 10-8
2.2 x 10-8
1.8 x 10-8
1.6 x 10-8
326
-------
By comparing the figures from Tables VI1-6 and VI1-7, one should be able to
decide about the particular soil liner permeability KI 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 VII-7.
The inspection of Equation 6 reveals that the required permeability is con-
trolled by the magnitude of y and Dt- The term -105.4 in the left hand
side of the equation is not very influential in determining the ki value.
Not so, when y and Dt are relatively small. In this situation the term
[hdCq/Kf)'1/(2*3 x)] becomes quite significant. Table VII-8 presents the
values of this term for different ranges of hj, x, Kf and q. The ranges
chosen are deliberately broad to overemphasize the significance of each
of the parameters.
TABLE VII-8.
VALUES OF THE TERM hd
OF hd, x, Kf and q.
-1/2+3X
FOR DIFFERENT VALUES
cm
q
sec
-1
cm
Kf
see"
1
hd •
-10
cm
hd
= -300
cm
x = 0.5
x = 5
x = 0.5
x = 5
io-6
10-8
10-4
ID'6
io-4
10~6
-37
-10
-139
-37
-13
-10
-17
-13
-1118
-300
-4168
-1118
-393
-300
-516
-393
The values for q, i.e. the required limiting flux, and kf, i.e. the saturated
permeability of the underlying soil, should be known to the designer of the
soil liner. Consequently, the designer should have no problems in deciding on
the row of the table corresponding to the particular system. The choice of a
particular column of Table VII-8 is a much more difficult step since it
involves information regarding the moisture characteristic curve (MCC) of the
underlying soil, hj and x. Since the MCC is not routinely determined in
geotechnical laboratories we will not recommend that it be determined. On the
other hand, some of the combinations between Kf, hd, and x are not possible.
Thus, a soil with a permeability Kf = 10'4 cm sec'1, an air-entry pressure
hd = -300 and a x = 0.5 probably does not occur in nature and the term in
Table VII-8 will almost never be lower than -IO3. As we mentioned in the
case in which the depth of the waste fluid, y, and that of the solid waste,
0^, are small, the relative significance of this term becomes important.
Table VII-8 indicates that this is true the lower the ratio q/Kf.
Table VI1-6 shows that, if the waste fluid plus the solid waste head is large
(e.g. larger than 50 feet), the permeability of the undisturbed underlying
327
-------
soil becomes critical in generating a low permissible flux, since for this
situation a deep soil liner of low permeability is required, and this situa-
tion may not be economical.
For the situation in which the condition of unsaturated flow is not observed,
i.e. when hf .1 hj, the downward movement in the underlying soil will occur
as saturated flow. According to McWhorter and Nelson (1979), such a situation
will be observed, for instance, for the following set of data:
y = 10 feet
Dt = 3 feet
DI = 1 foot
Kt = 10~4 cm sec'1
K! = 10"8 cm sec"1
Kf = 1CT7 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 = K (L + y + Dt * D] "hc)
(L + Dt + D] )
The calculated flux below the soil liner when the wetting front is at a
distance L equal to 10 m below the liner, will be 1.13 x 10~7 cm sec -1 .
If the soil porosity, n, is equal to 0.4 and the initial volumetric moisture
content e^ equal to 0.25, the relationship between time t and L can be
expressed, using:
n-e-j
Kf DT Kf , ,L + y + Dt + Dl -
L + (°t + ] - y - °t - Dl + hc) ln ( I
D]
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- Oj =
0.15), the length of the waste effluent column saturating the underlying soil
is equal to 150 cm. The ratio of 150 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.
328
-------
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 (hj and x).
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 hj and x values.
d. The temporary physico-chemical retention of the 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 change of chemical species, etc., are expected to
be connected in a more complex manner.
The most important merit of the presented analysis is that it considers the
flow to be unsaturated which is a reality in the field, in most instances.
The analysis for design can be carried out using other procedures. If the
system is more complicated than the one presented in our example, advantage
can be gained by using a computer assisted numerical analysis.
Note: See Chapter 5 for references.
329
-------
APPENDIX VIII
CASE STUDY ANALYSIS METHODOLOGY
This Appendix illustrates the case study method of analysis for developing
project costs, and possibly other project components. Depending upon the type
and size of project envisioned, the case study method can range from a fairly
simple analysis to a very complex procedure. Our example case study is a
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 waste
impoundment facility, which is to serve the surrounding metropolitan area
containing several industrial concerns. The site is flat and the facility has
the design criteria and parameters shown in Table VIII-1.
TABLE VIII-1. DESIGN CRITERIA AND PARAMETERS
Item Criteria value
Flow
Average design flow 60 gpm (4000 ft3/day)
Pond
Minimum requirement 120 acres
Cell size 15 acres
Number of cells 8
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
330
-------
The engineer for the facility has determined that thin polymeric membrane
liners are necessary to contain the wastes adequately. That decision was
effected by the inadequacy of the native soil and the unavailability of a
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 freeboard 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 be minimized by maintaining
solids in a slurry or liquid state. Total design depth of the pond is the sum
of the required freeboard, the minimum storage depth necessary to maintain the
contents in a liquid state, and the design storage depth. In order to main-
tain operation flexibility and maximize efficiency and effectiveness, the
impoundment is divided into smaller cells. Each cell has an area of 15 acres.
In case of leakage or maintenance operations, liquid wastes can be pumped 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 VIII-2 presents the capital costs for the waste impoundment facility.
Table VIII-3 shows the operating costs and Table VIII-4 presents the total
annual costs of the facility.
331
-------
TABLE VIII-2. CAPITAL COSTS FOR WASTE IMPOUNDMENT FACILITY
Costa,
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
Subtotal 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.
bPrimary liner and secondary liner plus installation. Based
on $0.85/sq.ft. reinforced chlorosulfonated polyethylene and
0.70/sq. ft. CPE.
cAssume 10 wells.
TABLE VII1-3. OPERATING COSTS FOR IMPOUNDMENT FACILITY
Item
Impoundment
Power
Operation and maintenance
Total
Annual cost
$/yr
24,880
116,120
141,000
Unit cost
$71,000 gal
0.024
0.11
0.13
332
-------
TABLE VIII-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.
333
-------
APPENDIX IX
SPECIFICATIONS FOR FLEXIBLE POLYMERIC MEMBRANE MATERIALS
The physical property values in the tables listed below are part of
a consensus standard being developed by the National Sanitation Foundation.
When specifying flexible membrane liners, these tables may provide useful
information but should be used with discretion. These values are preliminary
and subject to change.
These specification tables represent current opinion of the data points to
characterize the membrane product as now on the market and are not proper for
product performance or installation or engineering design criteria per se.
For example, the low temperature resistance numbers represent qualities for"~a
few minutes at a given temperature and must not be interpreted or extrapolated
into installation temperature qualities or comparisons.
LIST OF PROPOSED NATIONAL SANITATION FOUNDATION STANDARDS FOR
FLEXIBLE MEMBRANE LINERS FOR WASTE DISPOSAL FACILITIES
Unsupported sheeting Supported sheeting
Designa- Vana- Designa- Varia-
Polymer tiona tions^ tion<* tionsb
Polyvinyl chloride (PVC) 1-A 3
Chlorinated polyethlyene (CPE),
thermoplastic 1-B 2 2-A 2
Butyl rubber (IIR) 1-C 3
Polychlorprene (Neoprene, CR) 1-D 3
High-density polyethylene (HOPE) 1-E 2
Ethylene propylene rubber (EPDM) 1-F 3 2-D 3
Epichlorohydrin rubber (ECO) 1-G 3 - -
Chlorinated polyethylene (CPE),
vulcanized 1-H 2
Elasticized polyolefin (ELPO) 1-1 1
Chlorosulfonated polyethylene
(CSPE) 1-J 1 2-B 3
Thermoplastic nitrile PVC - 2-C 3
Elasticized PVC - 2-E 1
^Designation of specification by National Sanitation Foundation (NSF).
"Number of variations either in gage or in type of liner.
Source: Meeting of NSF Joint committee of Flexible Mebrane Liners,
July 22-24, 1980.
334
-------
TABLE 1A. MATERIAL PROPERTIES
UNSUPPORTED POLYVINYL CHLORIDE (PVC)
Test Gauge (nominal)
Property
Thickness
Specific Gravity
(minimum)
Minimum Tensile Properties
(each direction)
1. Breaking Factor
(pounds/inch width)
2. Elongation at Break
(percent)
3. Modulus (force) at 100%
Elongation (pounds/inch width)
Tear Resistance (pounds.
minimum)
Low Temperature
Dimensional Stability
(each direction, percent
change maximum)
Water Extraction
Volatile Loss
Method
ASTM D1593
Para 8.1.3
ASTM D792
Method A
ASTM D882
Method A or B
(1 inch wide)
Method A or B
Method A or B
ASTM D1004
ASTM D1790
ASTM D1204
212°F. 15min.
ASTM D1239
(as modified
in Appendix A)
ASTM D1203
Method A
20
±5%
1.20
46
300
18
6
-15'F
±5
-.35%
max.
0.7%
max.
30
±5%
1.20
69
300
27
8
-20"F
±5
-.35%
max.
0.5%
max.
45
+5%
1.20
104
300
40
11
-20°F
±5
-.35%
max.
0.4%
max.
Resistance to Soil Burial1
(percent change maximum
in original value)
1. Breaking Factor
2. Elongation at Break
3. Modulus at 100% Elongation
Bonded Seam Strength1
(factory seam, breaking
factor, ppi width)
Hydrostatic Resistance
(pounds/sq. in. minimum)
ASTM D3083
120 day soil burial
(as modified
in Appendix A)
ASTM D3083
(as modified in
Appendix A)
ASTM D751
Method A
-5
-20
±10
36.8
60
-5
-20
±10
-5
-20
±10
55.2 83.2
82
100
'Test value of "after exposure" sample is based on precut sample dimension. 120 day test is required for initial certification.
factory bonded seam strength is the responsibility of the fabricator.
The physical property values listed are part of a consensus standard being
developed by the National Sanitation Foundation. When specifying flexible
membrane liners, these tables may provide useful information, but should be
used with discretion. These values are preliminary and subject to change.
335
-------
Property
TABLE IB. MATERIAL PROPERTIES
UNSUPPORTED CHLORINATED POLYETHYLENE (CPE)
Gauge (nominal)
Test
Method
20
30
Thickness
Specific Gravity
(minimum)
Minimum Tensile Properties
(each direction)
1. Breaking Factor
(pounds/inch width)
2. Elongation at Break
(percent)
3. Modulus (force) at 100%
elongation (pounds/inch
width)
Tear Resistance (pounds,
minimum)
Low Temperature
Dimensional Stability
(each direction, percent
change maximum)
Water Extraction
Volatile Loss
Resistance to Soil Burial'
(percent change maximum
in original value)
1. Breaking Factor
2. Elongation at Break
3. Modulus at 100%
Elongation
Bonded Seam Strength"
(factory seam, breaking factor
ppi width)
Hydrostatic Resistance
(pounds/sq. in. minimum)
Percent CPE Resin by Weight
of total polymer
ASTM D1593
Para. 8.1.3
ASTM D792
Method A
ASTM D882
Method A or B
Method A or B
Method A or B
ASTM D1004
ASTM D1790
ASTM D1204
212°F, 15min.
ASTM D1239
(as modified in
Appendix A)
ASTM D1203
Method A
ASTM D3083
120 day soil burial
(as modified in
Appendix A)
ASTM D3083
(as modified in
Appendix A)
ASTM D751
Method A
NSF verification9
1.20
34
250
8
3.5
-20° F
±16
-0.35%
max.
0.7%
max.
-5
-20
HO
27
75
>50
±5%
1.20
43
300
12
4.5
-20°F
±16
-0.35%
max.
0.5%
max.
-5
-20
+ 10
34
100
>50
'Test value of "after exposure" sample is based on precut sample dimension, 120 day test is required for Initial certification.
'Factory bonded seam strength is the responsibility of the fabricator.
'NSF verification procedures described in Appendix _..
The physical property values listed are part of a consensus standard being
developed by the National Sanitation Foundation. When specifying flexible
membrane liners, these tables may provide useful information, but should be
used with discretion. These values are preliminary and subject to change.
336
-------
TABLE 1C. MATERIAL PROPERTIES
UNSUPPORTED BUTYL RUBBER
Property
Thickness
Specific Gravity
Minimum Tensile Properties
(each direction)
Test
Method
ASTM D1593
Para. 8.1.3
ASTM D297
ASTM 041 2
(as modified in
Appendix A)
Gau
30
+ 15%
-10%
1.20±.05
ge (nomli
45
+ 15%
-10%
1.20±.05
nal)
60
+ 15%
-10%
1.20±.05
1. Breaking Factor
(pounds/inch width)
2. Elongation it Break
(percent)
Tear Resistance (pounds,
minimum)
Low Temperature
Dimensional Stability
(each direction, percent
change maximum)
Resistance to Soil Burial1
(percent change maximum in
original value)
1. Breaking Factor
2. Elongation at Break
Bonded Seam Strength'
(factory seam, breaking
factor, ppi width)
Water Absorption
(percent, maximum)
Shore A Hardness
(points)
Ozone Resistance
Heat Aging
1. Elongation (percent,
minimum)
2. Breaking Factor
(pounds/inch width, minimum)
ASTM 0624
ASTM 0746
Procedure B
ASTM 01204
212°F, 7 days
ASTM D3083
120 day soil burial
(as modified in
Appendix A)
ASTM 03083
(as modified in
Appendix A)
ASTM 0471
158°F, 168 hours
ASTM D2240
5 second reading
ASTM 01149
100 hours, 50 pphm
104°F. 20% extension
ASTM 0573
7 days at 240°F
36.0
300
54.0
300
6
72.0
300
8
•40°F -40°F -40'F
±2 ±2 ±2
±10
±20
28.8
±2
±10
±20
43.2
±2
±10
±20
57.6
±2
60±10 60±10 60±10
No Cracks No Cracks No Cracks
7X 7X 7X
210
25.2
210
37.8
210
50.4
-------
TABLE 1D. MATERIAL PROPERTIES
UNSUPPORTED POLYCHLOROPRENE (CR)
Property
Thickness
Test
Method
ASTM D1593
Para 8.1.3
Gauge (nominal)
30
+ 15%
-10%
45
+ 15%
-10%
60
+ 15%
-10%
Specific Gravity
Minimum Tensile Properties
(each direction)
1. Breaking Factor
(pounds/inch width)
2. Elongation at Break
(percent)
Tear Resistance (pounds,
minimum)
Low Temperature
Dimensional Stability
(each direction, percent
change maximum)
Resistance to Soil Burial'
(percent change maximum in
original value)
1. Breaking Factor
2. Elongation at Break
Bonded Seam Strength2
(factory seam, breaking
factor, ppi width)
Water Absorption
(percent, maximum)
Shore A Hardness
(points)
Ozone Resistance
Heat Aging
1. Elongation (percent,
minimum)
2. Breaking Factor
(pounds/inch width, minimum)
ASTM D297
ASTM 0412
(as modified in
Appendix A)
ASTM D624
ASTM D746
Procedure B
ASTM D1204
212°F, 7 days
ASTM D3083
120 day soil burial
(as modified in
Appendix A)
ASTM D3083
(as modified in
Appendix A)
ASTM D471
158°F, 168 hours
ASTM D2240
5 second reading
ASTM D1149
100 hours, 50 pphm
104°F, 20% extension
ASTM D573
70 hours at 212°
1.48±.05 1.48±.05 1.48 + .05
45.0 67.5
250 250
4 6
90.0
250
8
-30°F -30°F -30°F
±2 ±2 ±2
±10
±20
36.0
±12
±10
±20
54.0
±12
60±10 60±10
±10
±20
72.0
±12
60±10
No Cracks No Cracks No Cracks
7X 7X 7X
150
38.2
150
57.4
150
76.5
'Test value of "after exposure" sample Is based on precut sample dimension. 120 day test is required for Initial certification.
'Factory bonded seam strength is the responsibility of the fabricator.
The physical property values listed are part of a consensus standard being
developed by the National Sanitation Foundation. When specifying flexible
membrane liners, these tables may provide useful information, but should be
used with discretion. These values are preliminary and subject to change.
338
-------
TABLE IE. MATERIAL PROPERTIES
UNSUPPORTED HIGH DENSITY POLYETHYLENE (HDPE)
Test Gauge (nominal)
Minimum Tensile Properties
(each direction)
1. Tensile Strength Yield
(pounds/inch width)
2. Tensile Strength at Break
(pounds/inch width)
3. Elongation at Yield
(percent)
4. Elongation at Break
(percent)
5. Modulus of Elasticity
(pounds/sq. in.)
Tear Resistance (pounds,
minimum)
Low Temperature
Dimensional Stability
(each direction, percent
change maximum)
Resistance to Soil Burial1
(percent change maximum
in original value)
1. Tensile Strength Yield
2. Tensile Strength at Break
3. Elongation at Yield
4. Elongation at Break
5. Modulus of Elasticity
Bonded Seam Strength2
(factory seam, breaking factor
ppi width
Environmental Stress Crack
(minimum, hours)
ASTM D638
ASTM D1004
ASTM D746
Procedure B
ASTM D1204
212°F, 15 min.
ASTM D3083
120 day soil burial
(as modified in
Appendix A)
ASTM D3083
(as modified in
Appendix A)
ASTM D1693
Property
Thickness
Specific Gravity
(minimum)
Method
ASTM 01 593
Para. 8.1.3
ASTM D792
Method A
80
±8%
0.930
100
±10%
0.930
120
120
10
500
80,000
400
-40° F
150
150
10
500
80,000
500
-40°F
±3
±10
±10
±10
±10
±10
108
500
±3
±10
±10
±10
±10
±10
135
500
'Test value of "after exposure" sample is based on precut sample dimension, 120 day test is required for initial certification.
'Factory bonded seam strength it the responsibility of the fabricator.
The physical property values listed are part of a consensus standard being
developed by the National Sanitation Foundation. When specifying flexible
membrane liners, these tables may provide useful information, but should be
used with discretion. These values are preliminary, and subject to change.
339
-------
Property
TABLE 1F. MATERIAL PROPERTIES
UNSUPPORTED ETHYLENE-PROPYLENE DIENE MONOMERS (EPDM)
Gauge (nominal)
Test
Method
30
45
60
Thickness
Specific Gravity
Minimum Tensile Properties
(each direction)
1. Breaking Factor
(pounds/inch width)
2. Elongation at Break
(percent)
Tear Resistance (pounds,
minimum)
Low Temperature
Dimensional Stability
(each direction, percent
change maximum)
Resistance to Soil Burial1
(percent change maximum in
original value)
1. Breaking Factor
2. Elongation at Break
Bonded Seam Strength1
(factory seam,
breaking Factor ppi width)
Water Absorption
(percent, maximum)
Shore A Hardness
(points)
Ozone Resistance
Heat Aging
1. Elongation (percent,
minimum)
2. Breaking Factor
(pounds/inch width, minimum)
ASTM 01593
Para 8.1.3
ASTM D297
ASTM 0412
(as modified in
Appendix A)
ASTM 0624
DieC
ASTM 0746
Procedure B
ASTM 01204
240CF, 7 days
ASTM 03083
120 day soil burial
(as modified in
Appendix A)
ASTM 03083
(as modified in
Appendix A)
ASTM D471
158°F, 168 hours
ASTM 02240
5 second reading
ASTM 01149
7 days, 100 pphm
104°F, 50% extension
ASTM D573
7 days at 240°
+ 15%
-10%
+ 15%
-10%
+ 15%
-10%
1.18±.03 1.18±.03 1.18±.03
42.0
300
±10
±20
33.6
±2
63.0
300
±10
±20
50.4
±2
84.0
300
468
-75°F -75°F -75°F
±2 ±2 ±2
±10
±20
67.2
±2
60±10 60±10 60±10
No Cracks No Cracks No Cracks
7X 7X 7X
210
36.0
210
54.0
210
72.0
'Test value of "after exposure" sample it based on precut sample dimension. 120 day teit ii required for Initial certification.
factory bonded team strength ia the responsibility of the fabricator.
The physical property values listed are part of a consensus standard being
developed by the National Sanitation Foundation. When specifying flexible
membrane liners, these tables may provide useful information, but should be
used with discretion. These values are preliminary and subject to change.
340
-------
TABLE 1G. MATERIAL PROPERTIES
UNSUPPORTED EPICHLOROHYDRIN POLYMERS (CO, ECO)
Property
Test
Method
Gauge (nominal)
30
45
60
Thickness
Specific Gravity
Minimum Tensile Properties
(each direction)
1. Breaking Factor
(pounds/inch width)
2. Elongation at Break
(percent)
Tear Resistance (pounds,
minimum)
Low Temperature
1. Homopolymer (CO)
2. Copolymer (ECO)
Dimensional Stabil'V
(each direction, percent
change maximum)
Resistance to Soil Burial1
(percent change maximum in
original value)
1. Breaking Factor
2. Elongation at Break
Bonded Seam Strength2
(factory seam,
breaking Factor ppi width)
Water Absorption
(percent, maximum)
Shore A Hardness
(points)
Ozone Resistance
Heat Aging
1. Elongation (percent,
minimum)
2. Breaking Factor
(pounds/inch width, minimum)
ASTM D1593
Para 8.1.3
ASTM D297
ASTM D412
(as modified in
Appendix A)
ASTM D624
ASTM D746
Procedure B
ASTM D1204
2128F, 7 days
ASTM 03083
120 day soil burial
(as modified in
Appendix A)
ASTM D3083
(as modified in
Appendix A)
ASTM D471
158CF, 168 hours
ASTM D2240
5 second reading
ASTM D1149
7 days, 100 pphm .
104°F, 20% extension
ASTM D573
7 days at 240°
+ 15%
-10%
+ 15%
-10%
+ 15%
-10%
1.49±.06 1.49±.06 1.49+.06
36.0
200
±10
±25
28.8
±10
70±8
54.0
±10
±25
43.2
±10
70±8
72.0
200
8
0°F 0°F 0°F
-20"F -20"F -20°F
±2 ±2 ±2
±10
±25
57.6
±10
70±8
No Cracks No Cracks No Cracks
7X 7X 7X
125
30.0
125
45.0
125
60.0
'Test value of "after expos ure" sample li bated on precut sample dimension. 1 20 day test Is required for initial certification.
'Factory bonded warn strength It the retpontibllity of the fabricator.
The physical property values listed are part of a consensus standard being
developed by the National Sanitation Foundation. When specifying flexible
membrane liners, these tables may provide useful information, but should be
used with discretion. These values are preliminary and subject to change.
341
-------
TABLE 1H. MATERIAL PROPERTIES
UNSUPPORTED CROSSLINKED CHLORINATED POLYETHYLENE (XLCPE)
Property
Thickness
Specific Gravity
Minimum Tensile Properties
(each direction)
1. Breaking Factor
(pounds/inch width)
2. Elongation at Break
(percent)
Tear Resistance (pounds,
minimum)
Low Temperature
Dimensional Stability
(each direction, percent
change maximum)
Resistance to Soil Burial1
(percent change maximum
in original value)
1. Breaking Factor
2. Elongation at Break
Bonded Seam Strength2
(factory seam, breaking factor,
ppi width)
Water Absorption
(percent, maximum)
Shore A Hardness (points)
Ozone Resistance
Heat Aging
1. Breaking Factor
(pounds/inch width, minimum)
2. Elongation (percent, minimum)
3. Hardness Change
Test
Method
ASTM D1593
Para 8. 1.3
ASTM D297
ASTM 04 12
(as modified in
Appendix A)
ASTM D624
DieC
ASTM D746
Procedure B
ASTM D1204
212°F, 7 days
ASTM D3083
120 day soil burial
(as modified in
Appendix A)
ASTM D3083
(as modified in
Appendix A)
ASTM D471
158°F, 168 hours
ASTMD2240
3 second reading
ASTM D1 149
7 days. 100 pphm, 104°F,
20% extension
ASTM D573
7 days, 250°F
Gauge
45
±5%
1.38 ±.05
54
300
5
-40°F
±2
±10
±10
44
+ 10
68 ±8
No Cracks
7X
48
200
8
(nominal)
60
±5%
1.38 ±.05
72
300
7
-40°F
±2
±10
±10
58
+ 10
68 ±8
No Cracks
7X
65
200
8
(maximum, points)
'Test value of "after exposure" sample is based on precut sample dimension, 120 day last Is required for Initial certification.
'Factory bonded seam strength is the responsibility of the fabricator.
The physical property values listed are part of a consensus standard being
developed by the National Sanitation Foundation. When specifying flexible
membrane liners, these tables may provide useful information, but should be
used with discretion. These values are preliminary and subject to change.
342
-------
TABLE II. MATERIAL PROPERTIES
UNSUPPORTED ELASTICIZED POLYOLEFIN
Property
Thickness
Specific Gravity
Test
Method
ASTM D1593
Para 8.1. 3
ASTM D297
Gauge (nominal)
20
+ 20%. -15%
0.92 ±.05
Minimum Tensile Properties
(each direction)
1. Breaking Factor
(pounds/inch width)
2. Elongation at Break
(percent)
3. Modulus (force) at 100%
elongation (pounds/inch
width)
Tear Resistance (pounds,
minimum)
Low Temperature
Dimensional Stability
(each direction, percent
change maximum)
Water Extraction
Volatile Loss
Resistance to Soil Burial1
(percent change maximum
in original value)
1. Breaking Factor
2. Elongation at Break
3. Modulus at 100%
Elongation
Bonded Seam Strength2
(factory seam, breaking factor
ppi width)
Heat Aging
1. Breaking Factor
(pounds/Inch width minimum)
2. Elongation at Break (percent)
Ozone Resistance
ASTM D412
DieC
(as modified in
Appendix A)
ASTM D1004
DieC
ASTM D1790
ASTM D1204
212°F, 15 min.
ASTM D1239
(as modified in
Appendix A)
ASTM D1203
Method A
ASTM D3083
120 day soil burial
(as modified in
Appendix A)
ASTM D3083
(as modified
in Appendix A)
ASTM D573
14 days, 158°F
ASTM D1149
100 pphm, 20% strain,
104°F, 7 days
34
500
12.8
5.1
•76°F
4
-0.35%
max.
0.5%
-10
-10
+ 10
27.2
33
425
No Cracks
7X
'Tstt value of "after expoiura" sample is based on precut sample dimension, 120 day test is required for Initial certification.
'Factory bonded seam strength is the responsibility of the fabricator.
The physical property values listed are part of a consensus standard being
developed by the National Sanitation Foundation. When specifying flexible
membrane liners, these tables may provide useful information, but should be
used with discretion. These values are preliminary and subject to change.
343
-------
TABLE 1J. MATERIAL PROPERTIES
UNSUPPORTED CHLOROSULFONATEO POLYETHYLENE (CSPE)
Test Gauge (nominal)
Property
Thickness
Specific Gravity
Minimum Tensile Properties
(each direction)
1. Breaking Factor
(pounds/inch width)
2. Elongation at Break
(percent)
3. Modulus (force) at 100% elongation
(pounds/inch width)
Tear Resistance (pounds,
minimum)
Low Temperature
Dimensional Stability
(each direction, percent
change maximum)
Water Extraction
Volatile Loss
Method
ASTM D1593
Para 8. 1.3
ASTM D297
ASTM D882
ASTM D882
ASTM D1004
DieC
ASTM D1790
Vt" mandrel, 4 hours.
Pass
ASTM D1204
211°F, 15min.
ASTM D1239
(as modified in
Appendix A)
ASTM D1203
Method A
30
+20%, -10%
1.40± .10
30
300
15
6
-20" F
25
-0.35%
0.5%
Resistance to Soil Burial1
(percent change maximum
in original value)
1. Breaking Factor
2. Elongation at Break
3. Modulus at 100% Elongation
Bonded Seam Strength2
(factory seam, breaking factor,
ppi width)
Ozone Resistance
ASTM D3083
120 day soil burial
(as modified in
Appendix A)
ASTM D3083
(as modified in
Appendix A)
ASTM D1149
100 pphm, 20% strain,
104°F, 7 days
-5
-20
+ 10
24
No Cracks
7X
'Test value of "after exposure" sample is based on precut sample dimension, 120 day test Is required for Initial certification.
'Factory bonded seam strength is the responsibility of the fabricator.
The physical property values listed are part of a consensus standard being
developed by the National Sanitation Foundation. When specifying flexible
membrane liners, these tables may provide useful information, but should be
used with discretion. These values are preliminary and subject to change.
344
-------
TABLE IK. MATERIAL PROPERTIES
UNSUPPORTED OIL RESISTANT POLYVINYL CHLORIDE (PVC-OR)
Twt Gauge (nominal)
Property
Thickness
Specific Gravity
(minimum)
Minimum Tensile Properties
(each direction)
1. Breaking Factor
(pounds/inch width)
2. Elongation at Break
(percent)
3. Modulus (force) at 100%
elongation (pounds/inch
width)
Tear Resistance (pounds,
minimum)
Low Temperature
Dimensional Stability
(each direction, percent
change maximum)
Water Extraction
Volatile Loss
Resistance to Soil Burial1
(percent change maximum
in original value)
1. Breaking Factor
2. Elongation at Break
3. Modulus at 100%
Elongation
Bonded Seam Strength'
(factory seam, breaking factor
ppi width)
Hydrostatic Resistance
(pounds/square inch minimum)
Method
ASTM D1593
Para 8.1.3
ASTM D792
Method A
ASTM 0882
Method A or B
(1 inch wide)
Method A or B
Method A or B
ASTM 01004
ASTM D1790
ASTM D1204
212°F, 15 min.
ASTM 01239
(as modified in
Appendix A)
ASTM 01203
Method A
ASTM 03083
120 day soil burial
(as modified in
Appendix A)
ASTM D3083
(as modified
in Appendix A)
ASTM 0751
Method A
30
±5%
1.20
69
300
27
8
0°F
5
-0.35%
max.
0.5%
- 5
- 20
-HO
SS.2
82
See Appendix A, Part IS, Oil Extraction, 7 days, percent maximum change
Weight @73.4±3°F
Weight @158±3°F
Tensile @73.4±3"F
Tensile @158±3'F
Elongation @73.4±3'F
Elongation @ 158±3°F
Neat*
Foot
- 5
- 15
+5
+ 15
- 10
- 10
Quit Com
Harmony #53 (Mazola)
- 5 - 5
•15 -15
+ 10
+ 15
- 10
• 15
+ 10
+ 15
- 10
- 10
ASTM
No. 2
- 5
• 10
+ 10
+15
- 10
• 20
'Test vslue of "after exposure" simple Is bated on precut urnpla dimemion, 120 day test ii required for Initial certification.
'Factory bondad seam strength la the responsibility of the fabricator.
The physical property values listed are part of a consensus standard being
developed by the National Sanitation Foundation. When specifying flexible
membrane liners, these tables may provide useful information, but should be
used with discretion. These values are preliminary and subject to change.
345
-------
TABLE 2A. MATERIAL PROPERTIES
Property
SUPPORTED CHLORINATED POLYETHYLENE (CPER)
Supported Finished Material
Test
Method Type 2 Type 3
Thickness
1. Overall (mils, minimum)
2. Over Scrim (mils, minimum)
Minimum Tensile Properties
(each direction)
1. Breaking Strength
(pounds, minimum, Fabric)
Tear Strength
(pounds, minimum)
Low Temperature
Dimensional Stability
(each direction, percent
change maximum)
Resistance to Soil Burial1
(percent change maximum
in original values)
a. Unsupported Sheet
1. Breaking Factor
2. Elongation at Break
3. Modulus at 100% Elongation
b. Membrane Fabric Breaking Factor
Bonded Seam Strength
(pounds, minimum)
Hydrostatic Resistance
(pounds/sq. in., minimum)
Ply Adhesion (each direction
pounds/in, width minimum)
Percent CPE Resin by Weight
of Total Polymer
ASTM D751
Optical Method
(Reference
Appendix A)
ASTM D751
ASTM D751
Tongue Method
8 x 8 in. sample
ASTM D2136
% in. mandrel
4 hrs., Pass
ASTM D1204
212°F, 1 hr.
ASTM D3083
120 day soil
burial, 30 mil sheet
(as modified
in Appendix A)
ASTM D/51
ASTM D751
(as modified in
Appendix A)
ASTM D75I
Method A, Procedure 1
ASTM D413
Machine Method
Type A
NSF verification
27
11
120
25
-40°F
34
11
200
35
-40°F
- 5
- 20
+ 10
- 10
96
160
10
>50
- 5
- 20
+ 10
- 10
160
250
8
>50
'Test value of "after exposure" sample is based on precut sample dimension, 120 day test is required for initial certification.
The physical property values listed are part of a consensus standard being
developed by the National Sanitation Foundation. When specifying flexible
membrane liners, these tables may provide useful information, but should be
used with discretion. These values are preliminary and subject to change.
346
-------
Property
TABLE 2B. MATERIAL PROPERTIES
SUPPORTED CHLOROSULFONATED POLYETHYLENE (CSPER)
Supported Finished Material
Type 1 Type 2 Type 3
Thickness
1. Overall (mils, minimum)
2. Over Scrim (mils, minimum)
Minimum Tensile Properties
(each direction)
1. Breaking Strength - fabric
(pounds minimum)
Tear Strength (pounds,
minimum)
1. Initial
2. After Heat Aging
Low Temperature
Dimensional Stability
(each direction
percent change maximum)
Resistance to Soil Burial1
(percent change maximum in
original values)
a. Unsupported sheet
1. Breaking Factor
2. Elongation at Break
3. Modulus at 100% Elongation
b. Membrane Fabric Breaking Factor
Bonded Seam Strength
(pounds, minimum)
Hydrostatic Resistance
(pounds/sq. in. minimum)
Ozone Resistance
Ply Adhesion (each direction,3
pounds/in, width minimum)
Volatile Loss
Test
Method
ASTM D751
Optical Method
(Reference
Appendix A)
ASTM D751
ASTM D751
Tongue Method
8 x 8 in. sample
212°F, 30 days
ASTM D2136
Vi in. mandrel,
4 hrs., Pass
ASTM D1204
212°F, 1 hr.
ASTM D3083
120 day soil burial
30 mil sheet
(as modified in
Appendix A)
27
11
60'
10
TBD
-40°F
7.5
- 5
- 20
+ 10
ASTM D751 - 10
ASTM D751 80
(As modified in
in Appendix A,
12 in./min.)
ASTM D751 80
Method A, Procedure 1
ASTM D1149
(As modified in 7X
7 days, 100 pphm
104°F. % in. bent loop)
ASTM D413 10
Machine Method
Type A
ASTM D1203 0.5%
Method A,
30 mil sheet
27
11
120
25
TBD
-40°F
- 5
- 20
+ 10
- 10
96
160
34
11
200
80
TBD
-40"F
- 5
-•20
+ 10
- 10
160
250
No Cracks No Cracks No Cracks
7X
10
0.5%
7X
10
0.5%
'Test value of "after exposure" sample is based on precut sample dimension. 120 day test is required for Initial certification.
Type 1 liner has two values. Coating it stronger than fabric and will withstand 100 pounds.
'Film tearing bond ii acceptable.
The physical property values listed are part of a consensus standard being
developed by the National Sanitation Foundation. When specifying flexible
membrane liners, these tables may provide useful information, but should be
used with discretion. These values are preliminary and subject to change.
347
-------
TABLE 2C. MATERIAL PROPERTIES
SUPPORTED THERMOPLASTIC NITRILE • PVC
Property
Test
Method
Supported Finished Material
Type 1 Type 2 Type 3
Thickness
1. Overall (mils, minimum)
2. Over Scrim (mils, minimum)
Minimum Tensile Properties
(each direction)
1. Breaking Strength - fabric
(pounds minimum)
Tear Strength (pounds,
minimum)
Low Temperature
Dimensional Stability
(each direction,
percent change maximum)
Resistance to Soil Burial1
(percent change maximum
in original values)
a. Unsupported Sheet
1. Breaking Factor
2. Elongation at Break
3. Modulus at 100% Elongation
b. Membrane Fabric Breaking Factor
Bonded Seam Strength
(pounds, minimum)
Hydrostatic Resistance
(pounds/sq. in. minimum)
Ozone Resistance
Ply Adhesion (each direction.1
pounds/in, width minimum)
Volatile Loss
ASTM D751
Optical Method
(Reference
Appendix A)
ASTM D751
ASTM D751
Tongue Method
8 x 8 in. sample
ASTM D2136
V, in. mandrel,
4 hrs.. Pass
ASTM D1204
212°F, 1 hr.
ASTM D3083
120 day soil
burial, 30 mil sheet
(as modified in
Appendix A)
ASTM D751
ASTM D751
(As modified
in Appendix A,
12 in./min.)
ASTM D751 80
Method A, Procedure 1
ASTM D1149
(As modified,
7 days, 100 pphm
104°F, V, in. bent loop)
ASTM D413
Machine Method
Type A
ASTM D1203
Method A
30 mil sheet
27 27
11 11
- 20
- 20
+30
- 10
64
- 20
- 20
+30
- 10
80
160
33
11
50' 100 180
8 20 60
-20°F -20°F -20°F
7.5 2 2
- 20
- 20
+30
- 10
144
250
No Cracks No Cracks No Cracks
7X 7X 7X
1.0%
1.0%
1.0%
'Test value of "after exposure" sample is bated on precut sample dimention. 120 day test is required for Initial certification.
Type 1 liner has two values. Coaling is stronger than fabric and will withstand 80 pounds.
'Film tearing bond is acceptable.
The physical property values listed are part of a consensus standard being
developed by the National Sanitation Foundation. When specifying flexible
membrane liners, these tables may provide useful information, but should be
used with discretion. These values are preliminary and subject to change.
348
-------
TABLE 2D. MATERIAL PROPERTIES
SUPPORTED THERMOPLASTIC EPDM
Property
Test
Method
Supported Finished Material
Type 1 Type 2 Type 3
Thickness
1. Overall (mils, minimum)
2. Over Scrim (mils, minimum)
Minimum Tensile Properties
(each direction)
1. Breaking Strength • fabric
(pounds minimum)
Tear Strength (pounds,
minimum)
Low Temperature
Dimensional Stability
(each direction
percent change maximum)
Resistance to Soil Burial1
(percent change maximum
in original values)
a. Unsupported Sheet
1. Breaking factor
2. Elongation at Break
3. Modulus at 100% Elongation
b. Membrane Fabric Breaking Factor
Bonded Seam Strength
(pounds, minimum)
Hydrostatic Resistance
(pounds/sq. in. minimum)
Ozone Resistance
Ply Adhesion (each direction,'
pounds/in, width minimum)
Volatile Loss
ASTM D751
Optical Method
(Reference
Appendix A)
ASTM D751
ASTM D751
Tongue Method
8 x B in. sample
ASTM D2136
VI in. mandrel.
4 hrs., Pass
ASTM D1204
21 ¥ F. 1 hr.
ASTM D3083
120 day soil
burial, 30 mil sheet
(as modified in
Appendix A)
27
11
27 33
11 11
50' 100 180
10 25 BO
-20CF -20°F -20°F
7.5 2 2
- 10
- 20
+30
ASTM D751 - 10
ASTM D751 64
(As modified in
Appendix A,
12 in./min.)
ASTM D751 80
Method A, Procedure 1
ASTM D1149
(As modified,
7 days, 100 pphm
104°F, % in. bent loop) .
ASTM D413 8
Machine Method
Type A
ASTM D1203 0.5%
Method A
30 mil sheet
- 10
- 20
+30
- 10
80
160
- 10
- 20
+30
- 10
144
250
No Cracks No Cracks No Cracks
7X 7X 7X
0.5%
0.5%
'Test value of "after exposure" temple it baiad on precut sample dimension. 120 day test Is required for initial certification.
Type 1 liner has two values. Coating Is stronger then fabric and will withstand 80 pounds.
•Film tearing bond is acceptable.
The physical property values listed are part of a consensus standard being
developed by the National Sanitation Foundation. When specifying flexible
membrane liners, these tables may provide useful information, but should be
used with discretion. These values are preliminary and subject to change.
349
-------
TABLE 2E. MATERIAL PROPERTIES
SUPPORTED ELASTICIZED POLYOLEFIN ALLOY
Property
Thickness
1. Overall (mils, minimum)
2 Over Scrim (mils, minimum)
Minimum Tensile Properties
(each direction)
1. Breaking Strength • fabric
(pounds, minimum)
Tear Strength (pounds.
minimum}
Low Temperature
Dimensional Stability
(each direction,
percent change, maximum)
Resistance to Soil Burial1
(percent change maximum in
original values)
a. Unsupported Sheet
1. Breaking Factor
2. Elongation at Break
3. Modulus at 100% Elongation
b. Membrane Fabric Breaking Factor
Bonded Seam Strength
(pounds, minimum)
Hydrostatic Resistance
(pounds/sq. in., minimum)
Ozone Resistance
Ply Adhesion (each direction
pounds/in, width minimum)
Volatile Loss
Water Extraction
Water Absorption
(percent gain, maximum)
Test
Method
ASTM D751
Optical Method
(Reference
Appendix A)
ASTM D751
Grab Method
ASTM D751
Tongue Method
8 x 8 in. specimen
ASTM D2136
Yt in. mandrel,
4 hrs., Pass
ASTM D1204
212°F, 1 hr.
ASTM D3083
120 day soil
burial, 30 mil sheet
(as modified in
Appendix A)
ASTM D751
ASTM D751
(As modified in
Appendix A)
ASTM 0751
Method A, Procedure 1
ASTM 01 149
(As modified,
7 days, 100 pphm
104°F, '/. in. bent loop)
ASTM D413
Machine Method
Type A
ASTM D1203
Method A
30 mil sheet
ASTM 01239
(as modified In
Appendix A)
ASTM 047 1
14days@158°F
14 days @ 70°F
Supported
Type A
30
11
300
60
-30°F
2
- 10
- 20
+ 15
- 10
240
600
No Cracks
7X
10
-1.0%
-0.35%
2
1
Finished Material
TypeB
30
9
400
125
-30°F
2
- 10
- 20
+ 15
- 10
320
500
No Cracks
7X
10
-1.0%
-0.35%
2
1
'Tett value of "after exposure" sample Is based on precut sample dimension. 120 day test is required for initial certiflcitlon.
The physical property values lieted are part of a consensus standard being
developed by the National Sanitation Foundation. When specifying flexible
membrane liners, these tables may provide useful information, but should be
used with discretion. These values are preliminary and subject to change.
350
-------
GLOSSARY OF TERMS RELATING TO LINER TECHNOLOGY
The intent of this glossary is to define the terms used in this Manual. A
glossary is considered desirable because of the diverse origins of the liner
technology and the broad spectrum of potential users of this Manual. If pos-
sible, generally accepted definitions were selected. The sources of each are
indicated with the definition. However, if an appropriate definition could
not be found, one was prepared. The definitions are presented by area of ex-
pertise, thus some definitions may appear more than once. The areas of ex-
pertise are:
1. Admix liner materials
2. Asphalt technology
3. Chemistry
4. Hazardous waste management
5. Hydrology
6. Polymeric membrane liners
7. Site construction
8. Soils science and engineering
9. Solid waste management
After the review period, we propose to combine the 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.
351
-------
GLOSSARY
ADMIX LINER MATERIALS
ADMIX - Two or more materials mixed together at or near the waste disposal
facility to be lined. These materials include asphalt concrete, Portland cement
concrete, and mixtures of soil and asphalt or Portland cement.
ADMIXTURES - Substances that are added to mortar, stucco, cement plaster and
concrete to produce specific results. They may or may not cause a chemical
reaction within the above substances, but usually a chemical reaction does
occur. Asphalts may be added for waterproofing compounds (Hornbostel, 1978).
COMPACTION - A process of densifying soil cement, soil asphalt, and asphalt
concrete by the use of sheepsfoot rollers,rubber-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 cement and water. As the cement
hydrates, the mixture forms a hard, durable, low strength concrete (Day,
1970).
352
-------
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,
D8).
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 or petroleum (Woods,
1960).
ASPHALT CEMENT - A fluxed or unfluxed asphalt specially prepared as to
quality and consistency for direct use in the manufacture of bituminous
pavements and having a penetration at 25*C (77eF) of between 5 and 300, under
a load of lOOg applied for five seconds (ASTM, D8).
ASPHALT MEMBRANE - A relatively thin layer of asphalt formed by spraying a
high viscosity, high softening point asphalt cement in two or more applica-
tions over the surface to be covered. It is normally l/4'r thick and buried to
protect it from weathering and mechanical damage.
ASPHALT PANEL - A laminate consisting of a core of blended asphalt, mineral
fillers, and reinforcing fibers sandwiched between protective sheets and a
protective coating of hot-applied asphalt.
BATTEN - In asphalt technology, a strip usually made of asphalt used to seal
the joints between 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, D8).
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 pentoxide, is used in the air blowing operation, the product is
known as catalytically-blown asphalt (Woods, 1960).
COAL TAR - Tar produced by the destructive distillation of bituminous coal
(ASTM, 08).
COURSE - See "Lift".
CUTBACK ASPHALT - Asphalt cement that has been liquefied by blending with
petroleum solvents which are in this context also called diluents. Upon
exposure to atmospheric conditions the diluents evaporate leaving the asphalt
cement to perform its function (Asphalt Institute, MS-5).
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EMULSIFIED ASPHALT - A mixture of asphalt and water in which the asphalt is
held in suspension in the water by an emulsifying agent. Emulsified asphalts
may be either cationic or anionic depending on the emulsifying agent used.
HYDRAULIC ASPHALT CONCRETE - Similar to asphalt concrete designed for roadway
paving, except that it has a higher mineral filler and asphalt content in
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 lift 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 asphalt in such
proportions that the mix can be applied hot by pouring or by mechanical
manipulation; it forms a voidless mass without being compacted (Asphalt
Institute, MS-12).
MINERAL FILLER - A finely divided mineral product of which at least 65% will
pass a No. 200 sieve which has a sieve opening of 74 urn. Pulverized limes-
tone is the most common manufactured filler, although other stone dust,
silica, hydrated lime, portland cement, and certain natural deposits of finely
divided matter are also used (Asphalt Institute, MS-5).
MIX - The amounts of aggregates and asphalt which are combined to give the
desired properties in the finished product.
PENETRATION - The consistency of a bituminous material expressed as the
distance in tenths of a millimeter (O.lmm) that a standard needle penetrates
vertically into a sample of the material under specified conditions of load-
ing, time, and temperature determined by ASTM D5 (ASTM, 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 D2398. Used in the classification of bitumen, par-
cularly 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.
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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 mil ligrams of calcium
carbonate equivalent per litre (EPA, 1977).
ANALYSIS - The determination of the nature or proportion of one or more
constituents of a substance, whether separated out or not (Webster's New World
Dictionary).
ASH (FIXED SOLIDS) - The incombustible material that 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, and/or biological reaction or
transformation (Federal Register, 1978).
(Five Day Biochemical Oxygen Demand) - A measure of the relative
oxygen requirements of waste-waters, effluents and polluted waters. BOD
values cannot be compared unless the results have been obtained under ident-
ical test conditions. The test is of limited value in measuring 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 is susceptible to oxidation by
a strong chemical oxidant (APHA - AWWA - WPCF, 1975).
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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).
DIFFUSION - The material permeation of two or more substances due to the
kinetic activity of their molecules, so that a uniform mixture or solution
results. Diffusion occurs with all forms of matter; it is most rapid for
gases, somewhat slower for liquids and for solids in solution.
EXTRACTABLES - Components or substances removable from a solid or liquid
mixture by means of an appropriate solvent (Hampel & Hawley, 1976).
HYDROCARBONS - An organic chemical compound containing mainly the elements
carbon and hydrogen. Aliphatic hydrocarbons are straight chain compounds of
carbon and hydrogen. Aromatic hydrocarbons are carbon-hydrogen compounds
based on the cyclic or benzene ring. They may be gaseous (CH4, ethylene,
butadiene), liquid (hexene, benzene), or solid (natural rubber, napthalene,
cis-polybutadiene) (Goodrich, 1979).
HYDROGEN SULFIDE (H2S) - A poisonous gas with the odor of rotten eggs that
is produced from the reduction of sulfates and the putrefaction of sulfur
containing organic matter (EPA, 1977).
ORGANIC CONTENT - Usually synonymous with volatile solids in an ashing test;
e.g. a discrepancy between volatile solids and organic content can be caused
by small traces of some inorganic materials such as calcium carbonate that
lose weight at temperatures used in determining volatile solids (EPA, 1972).
OSMOSIS - The diffusion of fluids through a semi-permeable membrane or porous
partition (Webster's New World 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 water. A pH of 7.0 indicates a neutral condition. A greater pH
indicates alkalinity and a lower pH, acidity. A one unit change in pH indi-
cates a tenfold change in acidity and alkalinity (Houston, 1974).
SOLUBILITY - The amount of a substance that can be dissolved in a given
solvent under specified conditions (Webster's New World Dictionary).
SUSPENDED SOLIDS - Solids that either float on the surface of or are in
suspension in water, wastewater, or other liquids, and which are largely
removable by laboratory filtering as described in "Standard Methods of the
Examination of Water and Wastewater", and referred to as nonfilterable residue
(EPA, 1977).
VOLATILE ACIDS - Lower acids up to and including capric acid, which are
volatile, wil1 vaporize, evaporate, or distill off, with steam (Bennett,
1947).
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VOLATILE SOLIDS - The material lost from a dried solid waste sample that is
heated until it is red in an open crucible in a ventilated furnace. The
weight of volatile solids is equal to that of the volatile matter plus that of
the fixed carbon (EPA, 1972).
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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 up hazardous components in the waste so as to
minimize the leaching of hazardous components and render the waste non-
hazardous or more suitable for disposal.
COLLECTION (DRAINAGE) SYSTEM - Structures and facilities for collecting and
carrying away water or other liquid (Asphalt Institute, MS-15).
COMPATIBILITY - Capability of existing together without adverse effects.
Applied primarily to combinations 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., 1978).
FLY ASH - All solids, including ash, charred paper, cinders, dust, soot, or
other partially incinerated matter that are carried in a gas stream (EPA,
1972).
HAZARDOUS WASTE - A solid waste or combination of solid wastes, which because
of its quantity, concentration or physical, chemical, 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 when improperly treated, stored, transported, or
disposed of, or otherwise managed (Public Law 94-580, 1976).
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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 waste-
water by forming an insoluble precipitate, usually a metallic hydroxide (EPA,
1977).
HERBICIDE - A type of pesticide, including so called weed-killers,silvicides
and defoliants, which kills or otherwise eliminates shrubs, small trees,
grasses, etc. There are both organic and inorganic herbicides: the latter is
typified by common salt, sodium borate, and various arsenical compounds; the
formed by 2,4-D and similar chlorinated compounds and by the defoliant
picloram (EPA, 1977).
IMPOUNDMENT - See "Surface Impoundment" in Site Construction Glossary.
INDUSTRIAL WASTE - The liquid wastes from industrial processes as distinct
from domesticor sanitary waste (EPA, 1977).
LEACHATE - See Solid Waste Management Glossary.
LINER - See Solid Waste Management Glossary.
MONITORING - All procedures used to systematically inspect and collect data 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 water quality
analysis or to measure groundwater levels.
PESTICIDE - See Solid Waste Management 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 for insect control, that kills rather
than repels (Webster's Collegiate Dictionary).
TOXIN - (1) Any of various unstable poisonous compounds produced by some
microorganisms and causing certain diseases. (2) Any of various similar
poisons, related to proteins, secreted by plants and animals (Webster's New
World Dictionary).
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GLOSSARY
HYDROLOGY
AQUIFER - A geologic formation, group of formations or part of a formation
that is capable of yeilding usable quantities of groundwater to wells or
springs (Fed. Reg., 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).
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 the direction of flow referred to as the Darcian velocity of
flux density (Fuller, 1978).
GROUNDWATER, FREE - (1) Groundwater in aquifer (2) Water in the saturated
zone beneath the land surface (Fed. Reg. 12/18/78).
GROUNDWATER TABLE - See "Water Table".
HEAD, (PRESSURE) - Pressure measured as an equivalent height of water.
HYDRAULIC GRADIENT - The change in hydraulic pressure per unit of distance in
a given direction.
HYDROLOGY - Science dealing with the 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 ratio, or in degrees (EPA, 1972).
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, 1972).
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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 of equal to atmospheric pressure (Fed. Reg., 1978).
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).
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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. (B.F. Goodrich, 1979).
AIR LANCE - A device used to test, in the field, the integrity of field seams
in plastic sheeting. It consists of a wand or tube through which compressed
air is blown.
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 plastic 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 a 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 (B.F. 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 rubber or plastic compounds (B.F.
Goodrich, 1979).
CHLORINATED POLYETHYLENE (CPE) - Family of polymers produced by chemical
reaction of chlorine on the linear backbone chain of polyethylene. The
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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
plastic material in the form of a solution, dispersion, hotmelt, or powder.
The term also applies to materials resulting from the application of a pre-
formed film to a fabric by means of calendering.
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, qv.
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 shape after removal of the stress which caused the
deformation (B.F.Goodrich, 1979).
ELASTOMER - See "Rubber".
EPDM - A synthetic elastomer based on ethylene, propylene, and a small amount
of a nonconjugated 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 chloromethyl group; including diamines, urea, thioureas,
2-mercaptoimidazoline, and ammonium sualts.
EVA - Family of copolymers of ethylene and Vinyl Acetate used for adhesives
and thermoplastic modifiers. They possess a wide range of melt indexes.
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.
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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 more thermoplastic films or
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).
LEND 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.
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 some oils.
NITRILE RUBBER - A family of copolymers of butadiene and acrylonitrile 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 related to thickness (Wren, 1972).
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).
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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 extensiblity. 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 (E/VA).
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
vinylchloride. 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. 101B, 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 liner 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.
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.
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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 tear 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-
metric-Megapascal 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 this type behave
similarly to crosslinked rubber. They have a limited upper temperature
service range which, however, is substantially above the temperature
encountered in waste disposal sites (200T may be too high for some TPE's).
THREAD COUNT - The number of threads 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
threads 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 polymer sheeting one or more plies thick without a
reinforcing fabric layer or scrim.
VULCANIZATE - A term used to denote the product of the vulcanization of a
rubber compound without reference to shape or form.
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 elastic
properties are conferred, improved, or extended over a greater range of
temperature (ASTM, STP 184A-1972).
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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.
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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-"Universal" - A blade with extensions on each side that protrude
forward at an obtuse angle to the blade and enabl-e 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 solid 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
fill.
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 a gas or water. The barrier is used to
prevent the movement of gas or water or to intercept them 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.
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GRADE - (1) See "Gradient". (2) To level off to a smooth horizontal or
sloping surface. (3) A datum or reference level. (4) Particle sized
distribution of an aggregate.
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 - Nonuniform 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 with a tamping area of about 2
inches. It is often used in the compacting of soils.
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.
SUBGRADE - The foundation or supporting soil layer for a liner. Subgrades can
be the surface of the ungraded native soil, but are more commonly specially
prepared, artifically compacted layers of soil.
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SUBSIDENCE - Settling or sinking of the land surface due to many factors such
as the decomposition of organic material, consolidation, drainage, and under-
ground failure (EPA, 1972)'
an
^j » * i
SUBSOIL - That part of the soil beneath the topsoil, usually not having
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 aeration ponds (Fed. Reg., 1978).
VENT - A smal1 hole or opening to permit passage or escape, as of a gas
(Webster's New World Dictionary).
370
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GLOSSARY
SOILS 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 atmo-
sphere. (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 (SSSA, 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 milliequivalents 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).
371
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BEDROCK - The solid rock underlying soils and the regolith at depths from
zero (where exposed by erosion) to several hundred feet (Brady, 1974).
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 - The sum total of exchangeable cations that a soil
can absorb; sometimes called "total exchange capacity", "base-exchange capa-
city" 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 U) the force per unit area
required to penetrate a soil mass with a 3 in. circular piston (approxi-
mately 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, D1883).
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 mm 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.
372
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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.
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:
F_p _ Exchangeable sodium (meq/IOOg soil)
~ Cation-exchange capacity (meq/IOOg 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 (Mitchell and Chan,
1960).
GRAVITATIONAL WATER - Water which moves into, through,-or out of the soil
under the influence of gravity.
HYDRAULIC CONDUCTIVITY - See "Permeability".
INFILTRATION RATE (INFILTRATION CAPACITY) - A soil characteristic determining
the maximum rate at which water can enter the soil under specified conditions,
including the presence of an excess of water. It has the dimensions of
velocity (SSSA, 1970).
INFILTRATION VELOCITY - the actual rate at which water is entering the soil at
any given time. It may be less than the maximum (tfie infiltration rate)
because of a limited supply of water (rainfall or irrigation). It has the
same units as infiltration rate (SSSA, 1979).
INTRINSIC PERMEABILITY - The property of a porous material that relates to
the ease with which gases or liquids can pass through it. The Darcy "k" is
multiplied byn'/g to obtain K', the intrinsic permeability, where:
n1 is the kinematic viscosity of the fluid in cm^ sec~l
g is the acceleration of gravity in cm/sec^
373
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n1 = n/p
where, n is viscosity in poises, g cm'1 sec'1
p is density of the fluid in g cm'3
For water at 23"C and q = 981 an 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).
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 (valence) in a crystal lattice without significantly
disrupting or changing the crystal structure of the mineral (SSA, 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, 1979).
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, tn %) when a sampleof soil or
waste is dried to a constant weight at 100-105 C (EPA, 1972).
MOISTURE CONTENT, OPTIMUM - The water content at which a soil-like mass
can be compacted to a maximum dry unit weight by a given compactive 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, 1979).
MOISTURE-WEIGHT PERCENTAGE - The moisture content expressed as a percentage
of the oven-dry weight of soil (SSSA, 1970).
374
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MONTMORILLONITE - An alumino-si 1 icate 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 silica tetrartedra of neighboring layers.
OVENDRY SOIL - Soil which has been dried at 105'C until it reaches a con-
stant weight (SSA, 1979).
PARTICLE DENSITY - The mass per unit volume of the soil particles. In tech-
nical work, usually expressed as g/cm^ (SSSA, 1970).
PARTICLE SIZE - The effective diameter of a particle measured by sedimenta-
tion, sieving, or micrometric methods (SSSA, 1970).
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
hydraulic gradients of the order of 1.0 or less (SSSA, 1979) (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
under conditions of laminar flow, such that the Darcy relationship is valid.
Permeability has dimensions of velocity, i.e., cm
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 developed 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).
POROSITY - The volume percentage of the total bulk not occupied by solid
particles (SSSA, 1970).
POTASSIUM FIXATION - The process of converting exchangeable to nonexchange-
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 - Soil particles between 0.05 and 2 mm in diameter (Brady, 1974).
375
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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 due 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 thorugh a No. 200 sieve and are larger
than 0.002 mm in equivalent diameter. (2) Soil textural class (Brady, 1974).
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).
SOIL PIPING OR TUNNELING - Accelerated erosion which results in subterranean
voids and tunnels (SSSA, 1970).
SOIL SOLUTION - The 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 STERILANT - Biocide applied to soils to prevent plant growth and insect
infestation.
SOIL STRUCTURE - The combination or arrangement of primary soil particles
into 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).
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).
TACTOID - An agglomeration of clay particles.
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
stiffens 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 voids
and solid soil.
WATER STABLE AGGREGATE - A soil aggregate which is stable to the action of
water such as falling drops or agitation as in wet sieve analysis (SSSA,
1970).
376
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GLOSSARY
SOLID WASTE MANAGEMENT
AQUIFER - See Hydrology Glossary.
BIODEGRADABLE - See Hazardous Waste Glossary.
BOD5 - See Chemistry Glossary.
CARCINOGEN - 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 (Federal Reg., 1978).
COD - See Chemical Glossary.
COLLECTION SYSTEM - See Hazardous Waste Glossary.
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 day.
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 soil
cover:
W & W
soil
VSW & Vsoil
Solid Waste: The number obtained by dividing the weight of solid waste
by its volume (EPA, 1972).
DISSOLVED SOLIDS - See Chemistry Glossary.
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 thereof (EPA, 1977).
FACILITY - Any land and appurtenances thereon and thereto, used for treat-
ment, storage and/or disposal of hazardous waste (Federal Reg., 1978).
FIELD CAPACITY - the maximum amount of moisture a soil or solid waste can
retain in a gravitional field without a continuous downward percolation (Fenn,
1975).
377
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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 (Federal Reg., 1978).
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 (Federal Reg., 1978). In this Manual a liner
includes: reworked or compacted soil and clay, asphaltic and concrete ma-
terials, 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, 8%; 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 chemical agents used to kill animal
and vegetable life which interferes with agricultural productivity regardless
of their mode of action (Hampel and Hawley, 1976).
pH - See Chemistry Glossary.
POLLUTANT - (1) A substance, material, chemical, 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 Manual, a
pollutant is a substance or material that degrades the quality of, or, direct-
ly or indirectly, presents a hazard to all or any of the following sectors of
the environment: water, groundwater, air, soil, plants, wildlife, 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).
378
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SANITARY LANDFILLING METHODS - Area, Quarry, Ramp, Trench, and Wet Areas,
Area: A method in which the wastes are spread and compacted on the
surface of the ground and cover material is spread and com-
pacted over them.
Quarry: Wastes are spread and compacted in a depression; cover ma-
terial is generally obtained elsewhere.
Ramp: 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.
Trench: Waste is spread and compacted in a trench; the excavated soil
is spread and compacted over the waste to form the basic cell
structure.
Wet Area: 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, sludge from a waste treatment plant, water
supply treatment plant, or air pollution control facility, and other discarded
material, including solid, liquid, semisolid, or contained gaseous material
resulting from industrial, commercial, mining, and agricultural operations,
and from community activities; does not include solid or dissolved 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 Chemistry Glossary.
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.
379
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WORKING FACE - That portion of a sanitary landfill where waste is discharged
by collection trucks and is compacted prior to placement of cover material
(EPA, 1972).
380
-------
REFERENCES
Glossary
APHA-AWWA-WPCF. 1975. Standard Methods for the Examination of Water and
Wastewater. 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.
The Asphalt Institute. 1969. Soils 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.
ASTM, 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,
Mich. 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. 8th ed. MacMillan
Publishing Co., Inc., New York, NY. 639 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 Reclamation, U.S. Department of the Interior, Denver, CO.
134 pp.
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 440/1-77-084.
U.S. Environmental Protection Agency, Washington, DC. 253 pp.
381
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Federal Register. 1978. Vol. 43, No. 243. Hazardous Waste - Proposed Guide-
lines and Regulations and Proposal on Identification and Listing. Wash-
ington, DC.
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. PB 286-995.
Goodrich, B.F., Co. 1979. Technical Rubber Terms Glossary. B.F. Goodrich
Chemical Division, Cleveland, Ohio.
Gregg, R. T. 1974. Development Document for Effluent Limitations Guidelines
and NewSource Performance Standards - Soap and Detergent Manufacturing,
Point Source Category. EPA - 440/1-74-018a. U.S. Environmental Pro-
tection Agency. Washington, DC. 202 pp. PB 238-613/4BA.
Hampel, C. A., and G. G. Hawley. 1976. Glossary of Chemical Terms. Van
Nostrand Reinhold 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
Mechanics and Foundations Div., ASCE. 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, Wise.
Webster's Collegiate Dictionary.
Webster's New World Dictionary.
Whittington, L. R. 1976. Whittington's Dictionary of Plastics. Technomic
Pub. Co., Inc., Stamford, Conn. 261 pp.
Woods, K. B., ed. 1960. Highway Engineering Handbook. McGraw-Hill Book Co.,
New York, NY.
Wren, E. 1973. Preventing Landfill Leachate Contamination. EPA 670/2-73-
021. U.S. Environmental Protection Agency, Cincinnati, Ohio. 109 pp.
PB 222-468.
382
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SELECTED BIBLIOGRAPHY
CHAPTER 2. DESCRIPTION OF WASTES AND IDENTIFICATION OF POLLUTANTS
Battelle Memorial Institute. 1974. Program for the Management of Hazardous
Wastes. EPA Contract No. 68-01-0762. U.S. Environmental Protection
Agency, Richland, Washington. 2 Vols. (PB-233-630; PB-233-631).
Booz Allen Applied Research Inc. 1973. A Study of Hazardous Waste Materials,
Hazardous Effects and Disposal Methods. EPA Cincinnati Contract No.
68-03-0032. Los Angeles, CA. 3 Vols. (PB-221-464).
Federal Power Commission. 1977. The Status of Flue Gas Desulfurization
Applications in the United States: A Technological Assessment. FPC. 80
pp.
Jones, J.W., J. Rossoff, R.C. Rossi, and L.J. Boornstein. 1974. Disposal of
By-products from Non-regenerable Flue Gas Desulfurization Systems.
Presented at the ASCE Annual and National Environmental Engineering
Conference
Radian Corp. 1975. Environmental Effects of Trace Elements from Ponded
Ash and Scrubber Sludge. EPRI-202. Electric Power Research Insti-
tute, Palo Alto, California.
CHAPTER 3. LINER MATERIALS AND LINER TECHNOLOGY
Bureau of Reclamation. 1967. Chapter of Lower Cost Canal Linings. In: Annual
Report of Progress on Engineering Research. Water Resources Research
Report No. 10. U.S. Dept. 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 Industrial
Sludge Leachates. In: Land Disposal of Hazardous Wastes - Proceedings of
the Fourth Annual Research Symposium. EPA-600/9-78-016. U.S. Environ-
mental Protection Agency, Cincinnati, Ohio. pp. 299-318.
Fuller, Wallace H. 1977. Movement of Selected Metals, Asbestos and Cyanide in
Soil: Applications to Waste Disposal Problems, EPA-600/2-77-020. US
Environmental Protection Agency. Cincinnati, Ohio. 242 pp.
Fuller, Wallace H. 1978. Investigation of Landfill Leachate Pollutant Attenu-
ation by Soils. EPA-600/2-78-158. U.S. Environmental Protection Agency,
Cincinnati, Ohio. 219 pp. PB 286-995.
383
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Mickey, M.E. 1968. Investigation of Plastic Films for Canal Linings. Water
Resources Research Report No. 19. Bureau of Reclamation, U.S. Deptart-
ment of the Interior, Washington. DC. 34 pp.
Jones, C.W. 1971. Laboratory Evaluation of Canal Soil Sealants. REC-ERC-71-1.
Bureau of Reclamation, U.S. Department of the Interior, Denver, Colorado.
18 pp.
LeBras, J. 1965. Introduction to Rubber. MacLaren and Sons Ltd., London, G.B.
105 pp.
Morrison, W.R. 1964. Evaluation of Sand-Phenolic Resin Mixtures as a Hard
Surface Lining, Lower Cost Canal Lining Program. Report No. 836. Bureau
of Reclamation, U.S. Department of the Interior, Denver, Colorado. 8
pp.
Petersen, R. and K. Cobian. 1976. New Membranes for Treating Metal Finishing
Effluents by Reverse Osmosis. EPA-600/2-76-197. U.S. Environmental
Protection Agency, Cincinnati, Ohio. 59 pp. PB 265-363/2BE.
CHAPTER 4. CHARACTERISTICS OF LINING MATERIALS IN SERVICE ENVIRONMENTS
Geswein, Allen J. 1975. Liners for Land Disposal Sites: An Assessment,
EPA/530/SW-137. U.S. Environmental Protection Agency, Washington, DC.
66 pp.
Hart, Fred C., Associates, Inc. 1978. The Impact of RCRA (PL 94-580) on
Utility Solid Wastes, EPRI FP-878. Electric Power Research Institute,
Palo Alto, CA.
Haxo, H. 1976. Assessing Synthetic and Admixed Materials for Lining Landfills.
In: Gas and Leachate from Landfills - Formulation, Collection and Treat-
ment. EPA-600/9-76-004. U.S. Environmental Protection Agency, Cincinnati,
Ohio. 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 Conservation
Directorate, Toronto, Ontario, Canada. 89 pp.
Stallman, R. 1976. Aquifer-Test Design Observation and Data Analysis. Book 3,
Applications of Hydraulics. Bl. U.S. Geological Survey, Washington, DC.
25 pp.
Styron, C. R., and Z.B. Fry. 1979. Flue Gas Cleaning Sludge Leachate/Liner
Compatibility Investigation - Interim Report. EPA-600/2-9-136. U.S.
Environmental Protection Agency, Cincinnati, Ohio. 78 pp. PB 80-100480.
Ware, S., and G. Jackson. 1978. Liners for Sanitary Landfills and Chemical and
Hazardous Waste Disposal Sites. EPA-600/9-78-005. U.S. Environmental
Protection Agency, Cincinnati, Ohio. 81 pp. PB 293-335/AS.
384
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CHAPTER 5. DESIGN AND CONSTRUCTION OF LINED WASTE DISPOSAL FACILITIES
Duvel, William A. 1979. Solid-waste Disposal: Landfill ing. Chemical Engine-
ering. 86 (14): 77-86.
Hass, J., and W. Lombardi. 1976. Landfill Disposal of Flue Gas Desulfurization
Sludge. Presented at the Third Symposium on Coal Utilization, National
Coal Association and Bituminous Coal Research, Inc., Louisville,
Kentucky. 13 pp.
Reid, G., L.E. Streebin, L.W. Canter, J.M. Robertson, and E. Klehro. 1971.
Development of Specification for Liner Materials for Use in Oil-Brine
Pits, Lagoons and Other Retention Systems. Draft Copy. Oklahoma Economic
Development Foundation, Bureau of Water Resources Research, Norman,
Oklahoma. 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. 20 pp.
Weston, Roy F., Inc. 1978. Pollution Prediction Techniques for Waste Disposal
Siting; A State-of-the-Art Assessment. EPA SW-162C; U.S. Environmental
Protection Agency, Cincinnati, Ohio. 477 pp.
CHAPTER 6. MANAGEMENT, OPERATIONS, AND MAINTENANCE OF LINED WASTE DISPOSAL
FACILITIES
Everett, L.G. 1976. Monitoring Groundwater Methods and Costs. EPA
600/4-76-023. U.S. Enivronmental Protection Agency, Cincinnati, Ohio.
140 pp. PB 257-133/9BA.
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.
Tinlin, R.M., ed. 1976. Monitoring Groundwater Quality: Illustrative Examples.
EPA 600/4-76-036. U.S. Environmental Protection Agency, Cincinnati, Ohio.
81 pp. PB 257-936/5BA.
Wehnan Engineering Corporation. 1976. Procedures Manual for Monitoring
Solid Waste Disposal Sites. U.S. Environmental Protection Agency,
Cincinnati, Ohio.
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