PB91-141846
EPA/600/2-91/002
October 1990
COMPILATION OF INFORMATION ON
ALTERNATIVE BARRIERS FOR LINER AND COVER SYSTEMS
by
David E. Daniel and Paula M. Estornell
University of Texas at Austin
Department of Civil Engineering
Austin, Texas 78712
Cooperative Agreement No. CR-815546-01-0
Project Officer
Walter E. Grube, Jr.
Municipal Solid Waste and Residuals Management Branch
Waste Minimization, Destruction and Disposal Research Division
U.S. Environmental Protection Agency
Risk Reduction Engineering Laboratory
Cincinnati, Ohio 45268
RISK REDUCTION ENGINEERING LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
REPRODUCEDBY
U.S. DEPARTMENT OF COMMERCE
NATIONAL TECHNICAL
INFORMATION SERVICE
SPRINGFIELD, VA 22161
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO. 2.
EPA/600/2-91/002
4. TITLE AND SUBTITLE
COMPILATION OF INFORMATION ON ALTERNATIVE BARRIERS
FOR LINER AND COVER SYSTEMS.
7. AUTHORlSt
D.E. DANIEL AND P.M. ESTORNELL
9. PERFORMING ORGANIZATION NAME AND ADDRESS
DEPARTMENT OF CIVIL ENGINEERING
THE UNIVERSITY OF TEXAS
AUSTIN, TX 78712
12. SPONSORING AGENCY NAME AND ADDRESS
RISK REDUCTION ENGINEERING LABORATORY - L1NL1NNAI1, UH
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY CINTI, OH 45268
3.RE< PB91-1418U6
5. REPORT DATE
October 1990
6. PERFORMING ORGANIZATION CODE
8. PERFORMING ORGANIZATION REPORT NO.
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
CR-815546
13. TYPE OF REPORT AND PERIOD COVERED
INTERIM
14. SPONSORING AGENCY CODE
EPA/600/14
15. SUPPLEMENTARY NOTES
PROJECT OFFICER: WALTER E. GRUBE, JR. FTS 684-7798
16. ABSTRACT
Workshop was held in Cincinnati, Ohio to present and discuss alternative barriers for liner and cover
systems. "Alternative" barriers include thin, manufactured, low-permeability materials that are being used and
being proposed for use in liner and cover systems for landfills, waste impoundments, site remediation projects,
secondary containment structures, and other facilities. The materials are being considered as an extra
component of a Uner or cover system, e.g., to back up a flexible membrane lint \FML), and in other cases, as
a substitute for a thicker layer of compacted, low-permeability soil.
This report contains a compilation of available information concerning alternative barrier materials and
summarizes the main points brought out in the woi kshop. There are four main alternative barrier materials
currently being produced. Three of them consist of a thin layer of bentonite sandwiched between two
geotextiles, and the fourth consists of a thin layer of bentonite glued to an FHL. All of the materials appear
to have a very low hydraulic conductivity (between 1 x 10 10 cm/s and 1 x 108 cm/s, depending upon the conditions
of testing). All of the materials are seamed in the field by overlapping sheets of hydrates. Data on the
hydraulic integrity of the seams are much less complete compared to data on the materials themselves. The
expansive nature of bentonite provides the bentonitic blankets with the capability of self-healing small
punctures, cracks, or other defects. The materials have many advantages, including fast installation with
light-weight equipment. The most serious shortcomings are a lack of data, particularly on field performance,
and the low shear strength of bentonite.
17. KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS
18. DISTRIBUTION STATEMENT
b. IDENTIFIERS/OPEN ENDED TERMS
19. SECURITY CLASS (This Report 1
20. SECURITY CLASS (Tliispagel
c. COSATI Field/Group
21 . NO. OF PAGES
93
22 PRICE
EPA Form 2220—1 (Rev. 4—77) PREVIOUS EDITION is OBSOLETE
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DISCLAIMER
The information in this document has been funded wholly or in part by the United States
Environmental Protection Agency under assistance agreement number CR-815546-01-0. It
has been subject to the Agency's peer and administrative review and has been approved for
publication as a U. S. EPA document. Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.
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FOREWORD
Today's rapidly developing and changing technologies and industrial products and
practices frequently carry with them the increased generation of materials that, if improperly
dealt with, can threaten both public health and the environment. The United States
Environmental Protection Agency is charged by Congress with protecting the Nation's land, air,
and water resources. Under a mandate of national environmental laws, the Agency strives to
formulate and implement actions leading to a compatible balance between human activities and
the ability of natural systems to support and nurture life. These laws direct the U.S. EPA to
perform research to define our environmental problems, measure the impacts, and search for
solutions.
The Risk Reduction Engineering Laboratory is responsible for planning, implementing,
and managing research, development, and demonstration programs to provide an authoritative,
defensible engineering basis in support of the policies, programs, and regulations of the U.S.
EPA with respect to drinking water, wastewater, pesticides, toxic substances, solid and
hazardous wastes, and Superfund-related activities. This publication is one of the products of
that research and provides a vital communication link between the researcher and the user
community.
This report documents the available information concerning manufactured materials that
might be utilized in liner and cover systems for landfills, impoundments, site remediation
projects, and secondary containment structures. The information compiled in this report was
obtained from literature, from information supplied by manufacturers, and from discussions at
a 2-day workshop held on June 7 and 8 in Cincinnati. This report will be useful to scientists,
engineers, and regulatory staff who are considering use of these types of materials.
E. Timothy Oppelt
Director
Risk Reduction Engineering Laboratory
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ABSTRACT
On June 7-8, 1990, a Workshop attended by approximately 75 people was held in
Cincinnati, Ohio, to present and discuss alternative barriers for liner and cover systems.
Alternative barriers include thin, manufactured, low-permeability materials that are being
used and being proposed for use in liner and cover systems for landfills, waste impoundments,
site remediation projects, secondary containment structures, and other facilities. In some
cases, the materials are being considered as an extra component of a liner or cover system, e.g.,
to back up a flexible membrane liner (FML), and in other cases the alternative barriers are
being considered as a substitute for a thicker layer of compacted, low-permeability soil.
This report contains a compilation of information available concerning alternative
barrier materials and summarizes the main points brought out in the workshop. There are four
main alternative barrier materials currently being produced. Three of them consist of a thin
layer of bentonite sandwiched between two geotextiles, and the fourth consists of a thin layer of
bentonite glued to an FML. All of the materials appear to have a very low hydraulic conductivity
to water {between 1 x 10~10 cm/s and 1 x 10'8 cm/s, depending upon the conditions of
testing). All of the materials are seamed in the field by overlapping sheets of the material and
relying upon the bentonite to form its own seal when it hydrates. Data on the hydraulic
integrity of the seams are much less complete compared to data on the materials themselves.
The expansive nature of bentonite provides the bentonitic blankets with the capability of self-
healing small punctures, cracks, or other defects. The materials have many advantages,
including fast installation with light-weight equipment. The most serious shortcomings are a
lack of data, particularly on field performance, and the low shear strength of bentonite.
The advantages of alternative barrier materials are significant, and the materials
warrant further evaluation.
I V
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Table of Contents
Foreword i i i
Abstract iv
List of Figures vii
List of Tables ix
1. Purpose of Workshop 1
2. Compacted Soil Liners 5
2.1 Materials 5
2.2 Important Variables 6
2.3 Construction of Compacted Soil Liners 1 0
2.3.1 Processing of Soil 1 0
2.3.2 Surface Preparation 1 2
2.3.3 Placement 1 2
2.3.4 Compaction 1 2
2.3.5 Protection 1 3
2.3.6 Quality Control Tests 1 3
2.3.7 Summary 1 3
2.4 Test Pads 13
2.5 Chemical Compatibility 1 4
2.6 Reliability of Soil Liners 14
3. Bentomat® 1 4
3.1 Description 1 4
3.2 Installation 1 5
3.3 Properties 1 6
3.3.1 Shear Strength 1 6
3.3.1.1 Direct Shear Tests 1 7
3.3.1.2 Tilt Table Tests 20
3.3.2 Hydraulic Properties 20
3.3.3 Seams 22
3.3.4 Mechanical Properties 22
3.4 Examples of Use 22
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Table of Contents (continued)
4. Claymax® 29
4.1 Description 29
4.2 Installation 31
4.3 Properties 30
4.3.1 Shear Strength 30
4.3.2 Hydraulic Properties 36
4.3.2.1 Tests with Water 3 8
4.3.2.2 Various Liquid and Chemical Leachates 40
4.3.2.3 Effects of Desiccation 4 2
4.3.2.4 Hydraulic Properties of Damaged Claymax 43
4.3.2.5 Composite Action 4 4
4.3.3 Seams 47
4.3.4 Swelling Characteristics 50
4.4 Examples of Use 5 1
5. Gundseal 53
5.1 Description 53
5.2 Installation 54
5.3 Properties 56
5.3.1 Physical Properties 56
5.3.2 Shear Strength 56
5.3.3 Hydraulic Properties 56
5.3.4 Seams 56
5.4 Examples of Use 5 8
6. Bentofix 59
6.1 Description 59
6.2 Installation 59
6.3 Properties 60
6.3.1 Shear Strength 60
6.3.2 Hydraulic Properties 60
6.3.3 Seams 60
6.3.4 Mechanical Properties 6 1
6.4 Examples of Use 61
7. Other Alternative Barrier Materials 63
v i
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8. Equivalency 65
9. Concerns 69
10. Informational Needs 71
11. List of References 74
12. Appendix: List of Participants 78
VII
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LIST OF FIGURES
Figure 1.1 Minimum Requirements for Liner Systems for Hazardous 2
Waste Landfills and Surface Impoundments
Figure 1.2 Recommended Design for Cover System for Hazardous Waste 3
Landfills and Surface Impoundments
Figure 2.1 Dry Unit Weight and Hydraulic Conductivity Versus Molding 7
Water Content for Typical Compacted, Low-permeability Soils
Figure 2.2 Effect of Method of Compaction Upon Hydraulic Conductivity of 8
a Silty Clay Soil
Figure 2.3 Effect of Compactive Energy Upon Hydraulic Conductivity of a 9
Silty Clay Soil
Figure 2.4 Permeabile Inter-Lift Zones Providing Hydraulic Connection 1 1
between High-Hydraulic-Conductivity Zones in Adjacent Lifts
Figure 3.1 Schematic Diagram of Bentomat® 1 5
Figure 3.2 Results of Direct Shear Tests with Interfacial Shear Occurring 1 8
between Dry Bentomat® and Sand
Figure 3.3 Results of Direct Shear Tests with Interfacial Shear Occurring 1 8
between Hydrated Bentomat® and Sand
Figure 3.4 Results of Direct Shear Tests with Interfacial Shear Occurring 1 9
between Dry Bentomat® and Clay
Figure 3.5 Results of Direct Shear Tests with Interfacial Shear Occurring 1 9
between Hydrated Bentomat® and Clay
Figure 3.6 Schematic Diagram of Tilt Table Tests 2 1
Figure 3.7 Results of Tilt Table Tests on Bentomat® 21
Figure 3.8 Results of Flexible-Wall Hydraulic Conductivity Tests on Bentomat® 23
Figure 4.1 Schematic Diagram of Claymax® 2 9
Figure 4.2 Mohr-Coulomb Failure Envelope for Direct Shear Tests Performed on 33
Hydrated Bentonite with Shear Plane Passing through the Bentonite
within Claymax®
VIII
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List of Figures (continued)
Figure 4.3 Mohr-Coulomb Failure Envelope for Direct Shear Tests Performed on 33
Hydrated Bentonite with Shear Plane Passing through the Interface
between Polypropylene Geotextile on Claymax®
Figure 4.4 Mohr-Coulomb Failure Envelope for Direct Shear Tests Performed on 34
Hydrated Bentonite with Shear Plane Passing through the Interface
between Polypropylene Geotextile on Claymax® and a Silty Sand
Figure 4.5 Results of Consolidated-Drained Direct Shear Tests on Claymax® 3 5
Figure 4.6 Results of Consolidated-Drained Direct Shear Tests on Claymax® 35
Figure 4.7 Results of Direct Shear Tests on Dry Samples of Claymax® 3 7
Figure 4.8 Results of Direct Shear Tests on Hydrated Samples of Claymax® 3 7
Figure 4.9 Results of Hydraulic Conductivity Tests on Claymax® Permeated 38
with Water
Figure 4.10 Schematic Diagram of Test to Evaluate In-Plane Flow 46
Figure 4.11 Schematic Diagram of Laboratory Test Designed to Evaluate 48
the Hydraulic Conductivity of Overlapped Seam
Figure 4.12 Schematic Diagram of Tanks Being Used to Measure Hydraulic 49
Conductivity of Bentonitic Blankets Containing Overlapped Seams
Figure 4.13 Results of Swelling Tests on Samples of Claymax® 50
Figure 5.1 Schematic Diagram of Paraseal and Gundseal 5 3
Figure 5.2 Overlap of Paraseal 5 5
Figure 5.3 Schematic Diagram of Hydraulic Conductivity Test on Overlapped 57
Seam of Paraseal
Figure 6.1 Schematic Diagram of Bentofix 59
Figure 6.2 Results of Direct Shear Tests on Bentofix 6 1
i x
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LIST OF TABLES
Table 3.1 Summary of Results of Direct Shear Tests on Bentomat® 2 0
Table 3.2 Summary of Results of Hydraulic Conductivity (K) Tests on Bentomat® 23
Table 3.3 Physical Property Test Results: Dry Bentomat® Containing High 25
Contaminant-Resistant Bentonite
Table 3.4 Physical Property Test Results: Hydrated Bentomat Containing High 26
Contaminant-Resistant Bentonite
Table 3.5 Physical Property Test Results for NonWoven Geotextile Component 27
of Bentomat®
Table 3.6 Physical Property Test Results for Woven Geotextile Component 28
of Bentomat®
Table 4.1 Material Specifications 30
Table 4.2 Summary of Results of Direct Shear Tests on Claymax® 34
Table 4.3 Results of Direct Shear Tests on Claymax® 3 6
Table 4.4 Results of Direct Shear Tests on Claymax® 36
Table 4.5 Results of Hydraulic Conductivity Tests on Claymax® 39
Permeated with Water
Table 4.6 Hydraulic Conductivity of Claymax® Permeated with Various 41
Liquids
Table 4.7 Results of Desiccation Studies on Sand Overlying Claymax® 42
Table 7.1 Summary of Results of Hydraulic Conductivity Tests on Fibersorb® 64
Table 8.1 Comparison of Differences in Alternative Barrier Materials 66
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Section 1
Purpose of Workshop
A 3-ft-(0.9 m) thick layer of low-permeability, compacted soil is a required
component of secondary liners for hazardous waste landfills and surface impoundments
regulated under the Hazardous and Solid Waste Amendments (HSWA) to the Resource
Conservation and Recovery Act (RCRA) [EPA, 1985]. The minimum primary liner for such
facilities must consist of a flexible membrane liner (FML). In addition, a secondary leachate
collection, detection, and recovery system (LCDRS) must be placed between the two liners
beneath hazardous waste landfills and surface impoundments, and, for solid-waste landfills, a
primary leachate collection and removal system (LCRS) must overlie the uppermost liner. The
minimum required components of a RCRA hazardous waste landfill liner system are sketched in
Fig. 1.1.
The recommended designs for cover systems over RCRA hazardous waste landfills and
closed surface impoundments include a 60-cm-thick layer of low-permeability, compacted soil
(EPA, 1989). A typical recommended design profile for a cover system is shown in Fig. 1.2.
Non-hazardous solid wastes are also regulated under RCRA, bui requirements have yet to
be published by the EPA. Presently, the states are establishing requirements for liner and
cover systems for non-hazardous waste landfills. Requirements vary, but most minimum
design requirements are similar to the concepts shown in Figs. 1.1 and 1.2.
No minimum design requirements for final covers over Superfund sites have been
established. Typically, however, some type of control of water infiltration is included in the
final cover design. Typically, a layer of low-permeability, compacted soil is part of the cover
design.
Thus, a layer of low-permeability, compacted soil is either a required or recommended
component of most liner systems for hazardous and non-hazardous waste landfills and surface
impoundments, as well as final covers over buried wastes or contaminated soil. Program and
regional officials of the U.S. Environmental Protection Agency (EPA) are currently evaluating
requests to substitute thin, manufactured clay blankets (alternative barriers) for thicker,
low-permeability, compacted soil in liners and covers. Representatives of EPA, as well as state
regulatory personnel and design engineers, need to be aware of the advantages and disadvantages
of the alternative barrier materials and need to have access to the full breadth of available
information about the various materials.
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.;, ill .,...
Primary
Liner
. i
S/SS/SS
Secondary
Composite
Liner
Waste
Primary Leachate Collection
and Removal System (LCRS)
Flexible Membrane
Liner (FML)
Secondary LCDRS
(May Use Geosynthetic)
Flexible Membrane
Liner (FML)
Compacted Soil
Permeability < 10-7 cm/s
Thickness > 3 ft
Figure 1.1. Minimum Requirements for Liner Systems for Hazardous Waste Landfills and
Surface Impoundments (from EPA, 1985).
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EPA-Recommended Cover Design
for Hazardous Wastes
60cm
30cm
60 cm
KXX>O^*!
*.••••-. I •,••.••.••.•%••.••. ••.•%•*. •*.•'>.•*,••.*%
^ftftftftftWift^iftsaft***^
Top Soil
Filter
Drainage Layer
FML
Low Permeability
Soil Layer
Waste
Figure 1.2. Recommended Design for Cover System for Hazardous Waste Landfills and Surface
Impoundments (from EPA, 1989).
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To disseminate information, a workshop was held on June 7 and 8, 1990, at the EPA's
Risk Reduction Engineering Laboratory (RREL) in Cincinnati, Ohio. The purpose of the
workshop was: (1) to present to EPA technical staff and contractors, as well as state regulatory
officials, the latest available information concerning alternative barriers; and (2) to exchange
ideas that might prove useful in making research on alternative barriers consistent with
ongoing, parallel studies and responsive to the needs of permit writers and regulation
developers.
The specific topics discussed at the workshop were as follows:
1. Presentation of background information on conventional, low-permeability,
compacted soil liners; functions served by compacted soil; performance of compacted
soil; factors to be considered in judging equivalency of other barrier materials
(presented by D. E. Daniel).
2. Description of alternative barriers (presented by Bentomat®, Claymax®, and
Gundseal representatives).
3. Discussion of parallel studies; results of various experiments performed on
compacted soil and manufactured barrier materials (presented by D. E. Daniel, P. M.
Estornell, and T. Zimmie).
4. Discussion of technical and regulatory concerns of EPA program offices, regional
offices, and state regulatory agencies about alternative barriers (open discussion).
5. Discussion of the prospects of using alternative barrier materials in liners and
covers for hazardous waste landfills, municipal solid waste landfills, and Superfund
closure sites; discussion of case studies (open discussion).
6. Discussion of research required to address the needs of permit writers and
regulation developers (open discussion).
This report will provide not only a summary of the proceedings of the Alternative
Barriers Workshop but will also document results from experiments recently conducted on
alternative barrier materials.
Background information on compacted soil barrkrs is provided in Section 2 of this
report. Information about Bentomat®, Claymax®, Gundseal, and Bentofix is presented in
Sections 3 through 6. Other alternative barriers are discussed in Section 7. The equivalency of
the alternative barrier materials is addressed in Section 8. Concerns about the alternative
barriers are summarized in Section 9. Research needs identified during the workshop are listed
in Section 10. A list of attendees is presented in the Appendix.
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Section 2
Compacted Soil Liners
Compacted soil liners are constructed primarily from naturally-occurring, low-
permeability soils, although the liner may contain processed materials such bentonite or even
synthetic materials such as polymers. Soil liners usually contain significant quantities of clay
and thus are frequently called "clay liners" even though clay may not be the most abundant
constituent in the liner material. Compacted soil liners are constructed in layers, called
"lifts," that are typically about 9 in. (225 mm) in loose thickness and 6 in. (150 mm) in
compacted thickness. Heavy compactors, or "rollers", are used to compact the soil.
2.1 Materials
The minimum requirements recommended by Daniel (1990) for most low-
permeability, compacted liners constructed from naturally-occurring soils are as follows:
Percentage Fines: > 30%
Plasticity Index: > 10%
Percentage Gravel: < 10%
Maximum Particle Size: 1 to 2 in. (25 to 50 mm)
Percentage fines is defined as the percent by dry weight passing the No. 200 sieve, which has
openings of 75 urn. Percentage gravel is defined as the percent by dry weight retained on a No. 4
sieve (4.76 mm openings). Local experience may dictate more stringent requirements, and, for
some soils, more restrictive criteria may be appropriate.
If suitable materials are unavailable locally, local soils can be blended with commercial
clays, e.g., bentonite, to achieve a low hydraulic conductivity. However, bentonite can be
attacked by some leachates -- compatibility tests may be required. A relatively small amount
of bentonite can lower hydraulic conductivity by several orders of magnitude (Daniel, 1987).
One should be cautious about using highly plastic soils (soils with plasticity indices >30
to 40%) because these materials form hard clods when the soil is dry and are very sticky when
the soil is wet. Highly plastic soils, for these reasons, are difficult to work with in the field.
However, special techniques, such as addition of lime, can ameliorate some of the problems with
construction utilizing highly plastic soils so that even these soils may be useable.
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2.2 Important Variables
Experience has shown that the water content of the soil, method of compaction,
compactive energy, clod size, and degree of bonding between lifts of soil can have a significant
influence on the hydraulic conductivity of compacted soil liners.
The water content of the soil at the time of compaction ("molding water content")
influences the hydraulic conductivity of saturated soil as shown in Fig. 2.1. When soils are
mixed to different water contents and then compacted, the dry unit weight is found to be
maximum at a certain molding water content, which is called the "optimum water content"
(dashed line in Fig. 2.1). Hydraulic conductivity is usually minimum for soils compacted at
molding water contents greater than the optimum. Experience has shown that the primary
causes for differences in hydraulic conductivity are differences in the arrangement of soil
particles (Mitchell, Hooper, and Campanella, 1965) and the fate of clods of clayey soil (Benson
and Daniel, 1990). With dry soils, the clods of soil are hard and difficult to remold. When the
soil is wetted to water contents higher than optimum, the clods are soft and more easily
remolded into a homogeneous mass that is free of large pores between clods. Thus, it is
important that the water content of the liner material be carefully controlled; otherwise,
undesirably large hydraulic conductivity may result, especially if the soil is too dry when it is
placed and compacted.
The method of compaction can influence the hydraulic conductivity of compacted soil.
Laboratory studies have shown that kneading the soil during compaction minimizes the
hydraulic conductivity (Fig. 2.2). Thus, footed rollers are typically utilized to compact soils in
the field; the "feet" from the drum of the roller penetrate into the soil to knead the soil during
compaction.
The energy of compaction is also an important variable. As shown in Fig. 2.3, the larger
the amount of energy delivered to the soil, the lower the hydraulic conductivity. In the field, it
is important to make an adequate number of passes of a heavy roller, and not to use too thick a
lift, to ensure that adequate compactive energy is delivered to the soil. The minimum weight
and number of passes varies with soil and equipment (Daniel, 1987; Herrmann and Elsbury,
1987; and Daniel, 1990).
The size of clods of soil can also influence hydraulic conductivity. Benson and Daniel
(1990) found that pulverization of clods of soil lowered the hydraulic conductivity of one
highly-plastic soil by a factor of 10,000 when the soil was compacted dry of optimum water
content. For wet soil with soft clods, the size of clods had little effect. For dry, hard soils, such
a shales, mudstones, or dry, highly-plastic soils, preprocessing the material with mechanical
pulverization may be required.
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Hydraulic
Conductivity
Dry Unit
Weight
Molding Water Content
Figure 2.1. Dry Unit Weight and Hydraulic Conductivity Versus Molding Water Content for
Typical Compacted, Low-permeability Soils.
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10
-5
10
-6
E
o
10
-7
10
-8
Optimum w —
Static
Compaction
i
Kneading Compaction
15 19 23 27
Molding w (%)
Figure 2.2.
Effect of Method of Compaction Upon Hydraulic Conductivity of a Silty Clay Soil
(from Mitchell, Hooper, and Campanella, 1965).
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-5
10
~ .~-6
IO
E
o
io7
,o8
116
108
100
92
i 1 r
i r 1 1 1
Increasing
Compactive
Effort
Optimum
Water
Content
Increasing Compactive
Effort
12 14 16 18 20 22 24
Molding w {%)
Figure 2.3. Effect of Compactive Energy Upon Hydraulic Conductivity of a Silty Clay Soil
(from Mitchell, Hooper, and Campanella, 1965).
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Experience has also demonstrated that lifts of soil must be bonded together to minimize
highly permeable zones at lift interfaces. The problem is illustrated in Fig. 2.4 for a liner
composed of 4 to 6 lifts. If each lift contains occasional hydraulic defects, liquid will permeate
primarily through those defects. If there is a highly permeable inter-lift zone, liquid can
spread laterally along the inter-lift zone until a hydraulic defect in the underlying lift is
reached. Thus, permeable inter-lift zones provide hydraulic connection between the more
permeable zones within adjacent lifts. If permeable inter-lift zones are eliminated, hydraulic
connection between "defects" in each lift is destroyed and a lower overall hydraulic conductivity
can be achieved. To maximize bonding between lifts, the surface of a previously-compacted lift
is roughened ("scarified"), and the new lift of soil is compacted with rollers that have feet that
fully penetrate the loose lift (to compact the new lift of soil into the surface of the previous
lift).
2.3 Construction of Compacted Soil Liners
2.3.1 Processing of Soil
Some liner materials need to be processed to break down clods of soil, to sieve out stones
and rocks, to moisten the soil, or to incorporate additives such as bentonite. Clods of soil can be
broken down with mechanical tilling equipment such as a rototiller. Stones can be sieved out of
the soil with large vibratory sieves or mechanized "rock pickers" passed over a loose lift of
soil. Road reclaimers (also called road recyclers) can process soil in a loose lift and crush
stones or large clods.
If the soil must be wetted or dried more than about 2 to 3 percentage points in water
content, the soil should first be spread in a loose lift about 12 in. (300 mm) thick. Water can
be added and mixed into the soil with agricultural tillage equipment or industrial mixers, or the
soil can be disced or tilled to allow it to dry uniformly. It is essential that time be allowed for
the soil to wet or dry uniformly. At least 1-3 days is usually needed for adequate hydration or
dehydration. Frozen soil should never be used to construct a soil liner.
Additives such as bentonite can be introduced in two ways. One technique is to mix soil
and additive in a pugmill. Water can also be added in the pugmill. Alternatively, the soil can be
spread in a loose lift that is 9 to 12 in. (222 - 300 mm) thick, the additive spread over the
surface, and a mechanical tiller or road reclaimer used to mix the materials. Several passes of
the mixer over a given spot may be needed, and the mixer should be operated in at least 2
different directions to minimize the possibility of strips of unmixed material. Water can be
added in the tiller during mixing or later, after mixing is complete. The pugmill is more
1 o
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Borehole
Lift 1
Lift 2
Lift 3
Lift 4
/
1 ^ L r ^
r* C
i ; \
^s X
"^ — ^
"\ r
^ r \ >
^ r (
Figure 2.4. Permeable Inter-Lift Zones Providing Hydraulic Connection between High-
Hydraulic-Conductivity Zones in Adjacent Lifts.
11
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reliable in providing thorough mixing, but, done carefully, in-field methods can provide
effective mixing.
2.3.2 Surface Preparation
It is crucial that each lift of a soil liner be effectively bonded to the overlying and
underlying lifts. The surface of a previously-compacted lift must be rough rather than smooth.
If the surface has been smoothed, e.g., with a finish roller at the end of a day's work shift, the
surface should be excavated to a depth of about 1 in. (25 mm) with a disc or other suitable
device before continuing placement of overlying lifts.
2.3.3 Placement
Soil is placed in a loose lift that is no thicker than about 9 in. (225 mm). If grade
stakes are used to gauge thickness, the stakes must be removed and the holes left by the stakes
sealed. Techniques that do not require penetration of the lift, e.g., laser controls, are preferable
to grade stakes. After the soil is placed, a small amount of water may need to be added to offset
evaporative losses, and the soil may be tilled one last time prior to compaction.
2.3.4 Compaction
Heavy, footed compactors with feet that fully penetrate a loose lift of soil are ideal. The
weight of the compactor must be compatible with the soil: relatively dry soils with firm clods
require a very heavy compactor whereas relatively wet soils with soft clods require a roller
that is not so heavy that it becomes bogged down in the soil. Care should be taken to ensure that
an adequate number of passes of the roller are made. Normal compaction specifications
typically require 6 to 8 passes of a roller to achieve the required density. Since the soil liner
is being build as a hydraulic containment structure, it is necessary to apply sufficient number
of passes that every portion of compacted soil receives the compactive energy applied by the feet
on the roller. The footprint area and the number of feet on the roller drum need to be taken into
account to calculate the minimum number of passes required for complete coverage of an area.
Additional passes beyond the theoretical minimum needed for 100 percent coverage should be
provided to account for the footprint overlap likely to occur in field construction. Experience
has shown that as many as 18 to 20 passes are required for some types of footed rollers to
achieve complete coverage. Since a kneading compaction helps to provide minimal hydraulic
conductivity, it is fallacious to use the common "walking out" endpoint to indicate that sufficient
compaction has been achieved. Experience indicates that minimum hydraulic conductivity has
been achieved while there remains some "waving" of the reworked soil ahead of the roller drum.
12
-------
"Walking out" needs to be monitored carefully as it may indicate that the soil is too dry to
achieve hydraulic conductivity objectives.
2.3.5 Protection
After compaction of a lift, the soil must be protected from desiccation and freezing.
Desiccation can be minimized in several ways: the lift can be temporarily covered with a sheet
of plastic, the surface can be smooth-rolled to form a relatively impermeable layer at the
surface, or the soil can be periodically moistened. The compacted lift can be protected from
damage by frost by avoiding construction in freezing weather or by temporarily covering the
lift with an insulating layer of material.
2.3.6 Quality Control Tests
A critical component in construction quality assurance is quality control (QC) testing.
For soil liners, the tests fall into two categories: (1) tests to verify that the materials of
construction are adequate, and (2) tests and observation to verify that the compaction process is
adequate. Great care must be taken to design an adequate program of QC testing and to repair
holes left from destructive QC tests. Details on QC testing are given by EPA (1986), Goldman et
al. (1988), and Daniel (1990).
2.3.7 Summary
Proper construction of soil liners is difficult. Materials must be carefully selected, the
soil may require extensive processing, the moisture content must be in the correct range, the
surface to receive a lift of soil must be prepared properly, the soil must be adequately
compacted, and each compacted lift as well as the entire liner must be protected from damage
caused by desiccation or freezing temperatures. Further information is provided by Daniel
(1987, 1990), Herrmann and Elsbury (1987), and EPA (1986, 1989).
2.4 Test Pads
The construction of a test pad prior to building a fu!l-sized liner has many advantages.
By constructing a test pad, one can experiment with molding water content, construction
equipment, number of passes of the equipment, lift thickness, and other construction variables.
Most importantly, though, one can conduct extensive field-scale destructive testing, including
QC testing and in-situ hydraulic conductivity testing, on the test pad. Test pads are
recommended by the EPA (1985) for confirming that the materials and methods of construction
13
-------
will provide an adequately low hydraulic conductivity for the soil-liner component in' RCRA
hazardous waste landfills and surface impoundments.
The test pad usually has a width of at least 3 construction vehicles (>10 m), and an equal
or greater length. The pad should ideally be the same thickness as the full-sized liner, but the
test pad may be thinner than the full-sized liner. (The full-thickness liner should perform at
least as well as, and probably better than, a thinner test section because defects in any one lift
become less important as the number of lifts increases). The in-situ hydraulic conductivity
may be determined in many ways, the large sealed double-ring infiltrometer is usually the best
large-scale test (Daniel, 1989).
2.5 Chemical Compatibility
The compatibility of low-permeability soil liners with wastes to be retained must be
assured. Daniel (1987) and Goldman et al. (1988) discuss the mechanisms of attack and
summarize available data.
2.6 Reliability of Soil Liners
Examples can be cited of soil liners that had unacceptabiy large hydraulic conductivity
and therefore failed to function effectively as hydraulic barriers (Daniel, 1987; and Goldman et
al., 1988). Inadequate construction or construction quality control have been the main causes
of problems. Good-quality soil liners can be constructed (Gordon et al., 1989) if construction
is carried out very carefully and adequate construction quality is applied.
14
-------
Section 3
Bentomat®
3.1 Description
Bentomat® is manufactured by American Colloid Company, 1500 West Shure Drive,
Arlington Heights, Illinois 60004 (telephone 708-392-4600). The material consists of a
minimum of one pound per square foot (4.9 kg/m2) of dry (maximum 12% moisture),
granular, sodium bentonite sandwiched between two polypropylene geotextiles (Fig. 3.1). The
upper geotextile is woven while the lower geotextile is non-woven. The weights of the
geotextiles can vary but are typically about 3 to 6 02. per square yard (102 to 204 g/m2).
Fibers from the upper geotextile are needlepunched through the layer of sodium bentonite and
into the lower geotextile (Fig 3.1). Variations of Bentomat® can be custom engineered to meet
site-specific needs. Also, one of four basic types of sodium bentonite may be incorporated into
Bentomat®- Each bentonite grade has different swelling properties and contaminant-resistant
properties. The four bentonites available have the following designations and properties.
"CS"- CS-50 (untreated, granular bentonite)
"SG"- SG-40 (polymer-treated, high-swelling bentonite)
"PL"- PLS-50, (medium-containment-resistant bentonite)
"SS"- SS-100 (high-contaminant-resistant bentonite).
Woven Geotextile
Needle-Punched
Fibers
vSodium Bentonite
%
w
••v
^\1^^xx^.1s.^.^^^^.^.^.^^^,^.^\xx^.xx
Non-Woven Geotextile
Figure. 3.1 Schematic Diagram of Bentomat®.
15
-------
The standard roll size of Bentomat® is currently 12 ft (3.6 m) wide and 100 ft (30 m)
long. The thickness of dry Bentomat® is approximately 1/4 in (6 mm).
Bemalux Inc., of Quebec, Canada, originated Bentomat® in 1980. The original
Bentomat® was constructed in the field by laying a sheet of geotextile on a smooth surface,
spreading a layer of sodium bentonite (about 3 Ibs/ft2, or 14.7 kg/m2) over the geotextiie, and
covering the bentonite with another geotextile. The prefabricated, needlepunched version of
Bentomat® was introduced in January, 1990, by American Colloid Company, which acquired
the U.S. patent rights for the product from Bemalux, Inc., in 1989.
3.2 Installation
The following discussion summarizes the manufacturer's recommendations for
installation. The subgrade should be compacted such that no rutting is caused by installation
equipment or vehicles. Subgrade or fill material should be free of angular or sharp rocks
larger than 1 inch in diameter. Organics or other deleterious materials should be removed.
Prior to the placement of Bentomat®, the surface should be graded to fill all major voids and
cracks.
Bentomat® is placed, beginning with the side slopes, by anchoring the panels in anchor
trenches and then unrolling the material down the slope. Panels may ?!so be pulled up from the
bottom of the slope to the anchor trench. Seams at the base of the slope should be a minimum of
5 ft (1.5 m) away from the toe of the slope. Seams along the side slopes should be
perpendicular to the toe of the slope. Panels on flat surfaces do not require any particular
orientation.
Seams are formed by overlapping one panel on another. Seam overlaps should be a
minimum of 6 in. (150 mm) wide with contacting surfaces that are flat and clear of any large
rocks, dirt, or debris. The panels are printed with 6-in. and 9-in. (150 and 230 mm)
guidelines along both edges to aid in assuring that the minimum overlap width is achieved.
American Colloid Company recommends sprinkling granular bentonite at a rate of
approximately 0.25 pounds per liner foot (35 g/m) over a 3-in. (76 mm) wide swath in the
overlap zone. Fasteners, anchor pins, or adhesives may be used on seams to keep panels in place
during backfilling operations.
For pipe penetrations, a small notch should be cut in the subbase around the
circumference of the pipe. Bentonite should then be packed around the pipe in the area of the
notch to form a thick bentonite seal. The Bentomat® panel should be slit with an "X" in the
center, placed over the penetration, and sealed with bentonite to produce a seal. A second piece
1 6
-------
of Bentomat® should then be cut and fit around the pipe with bentonite applied between the
overlap and to any gaps that may exist.
A 12-in. (300 mm) thick layer of protective soil should be placed over the Bentomat®
liner, taking care to keep 12 in. (300 mm) of material between the liner and any machinery or
equipment at all times. Sharp turns and quick stops or starts should be avoided to prevent
pinching or moving the liner. When placing riprap on slopes, a layer of heavier geotextile
should be incorporated into the liner for added puncture resistance (American Colloid Company,
1990).
3.3 Properties
3.3.1 Shear Strength
3.3.1.1 Direct Shear Tests
Direct shear tests were performed on soil/Bentomat® interfaces by J&L Testing
Company (1990a). The frictional resistance between Bentomat® and sand and between
Bentomat® and clay was measured in a direct shear device for both dry and hydrated samples.
The tests were apparently designed to cause failure along the sand/Bentomat® or
clay/Bentomat® interface and not to produce failure within the bentonite.
Samples of Bentomat® measuring 100 mm by 100 mm (3.9 in. by 3.9 in.) were placed
against soil in a direct shear box and subjected to a constant rate of displacement of 0.009
in/min (0.24 mm/min). Normal stresses of 150, 300, and 450 psf (7.2, 14.4, and 21.5
kPa) were applied to each of the specimens. No standard method of testing these types of
materials exists; apparatus of the type normally used for soils was apparently utilized. Failure
occurred in most incidences at a horizontal displacement of approximately 0.2 in. (5 mm). The
time to failure is calculated by the authors of this report to be about 20 minutes. It is doubtful
that the rate of shear was slow enough to allow full dissipation of water pressures generated
within hydrated clay or bentonite during shear. For this reason, the test results probably do
not reflect the long-term performance of the materials or interfaces.
Results of direct shear tests are presented in Figs. 3.2 through 3.5 and are summarized
in Table 3.1. The failure envelopes shown in Figs. 3.2 through 3.5 were calculated by linear
regression. The calculated friction angles are between 28° and 41°.
For both the sand/Bentomat® and clay/Bentomat® tests, the friction angles were 7 to
10° higher when the bentonite was hydrated compared to dry bentonite. The authors of this
report would have expected lower friction angles with hydrated bentonite, but the results of the
tests were the opposite of this expectation. No explanation as to the cause for higher friction for
hydrated versus dry bentonite is apparent, except that the tests may more nearly reflect short-
17
-------
CO
co
CD
CO
CO
0)
-C
CO
400
300
200
100
c = 85 psf, Phi = 28 degrees
100 200 300 400
Normal Stress (psf)
500
Figure 3.2. Results of Direct Shear Tests with Interfacial Shear Occurring between Dry
Bentomat® and Sand (J & L Testing Company, 1990a).
CO
CO
CO
CO
CO
Q)
_c
CO
Figure 3.3.
400
300
200
100
c = 10 psf, Phi = 35 degrees
100 200 300 400
Normal Stress (psf)
500
Results of Direct Shear Tests with Interfacial Shear Occurring between Hydrated
Bentomat® and Sand (J & L Testing Company, 1990a).
18
-------
CO
Q.
CO
CO
CD
CO
l_
05
CO
400
300
200
100
1 00
c = 105 psf, Phi = 31 degrees
200
300
400
Normal Stress (psf)
500
Figure 3.4. Results of Direct Shear Tests with Interfacial Shear Occurring between Dry
Bentomat® and Clay (J & L Testing Company, 1990a).
CO
Q.
CO
CO
CO
1_
CO
0)
_c
CO
500
400 -
300 -
200 -
100 -
c = 77 psf, Phi = 41 degrees
100 200 300 400
Normal Stress (psf)
500
Figure 3.5. Results of Direct Shear Tests with Interfacial Shear Occurring between Hydrated
Bentomat® and Clay (J & L Testing Company, 1990a).
19
-------
term, undrained conditions rather than long-term, fully-drained conditions. These data are
specific to the sand and clay soils tested. American Colloid Company recommends against
extrapolating results to other soils; instead, site-specific testing is recommended.
Table 3.1 Summary of Results of Direct Shear Tests on Bentomat®
(J &L Testing Company, 1990a)
Cohesion Friction Angle
Sample (psf) (degrees)
Dry Bentomat® with Sand 85 28
Hydrated Bentomat® with Sand 10 35
Dry Bentomat® with Clay 105 31
Hydrated Bentomat® with Clay 77 41
(Note: 100 psf = 4.8 kPa)
3.3.1.2 Tilt Table Tests
Tilt table tests were performed by J & L Testing Company (1990a). A multi-layered
system composed of sand, high density polyethylene (HOPE) sheet, hydrated Bentomat®' and
geonet was placed on a tilt table (Fig. 3.6) to measure the friction angle along the weakest
interface (between smooth HOPE and hydrated Bentomat®). Normal stresses of 130 and 385
psf (6.2 and 18.4 kPa) were applied to the HDPE/Bentomat® interface, the table was inclined
slowly, and the inclination at which sliding was first observed was recorded. No information on
the time to failure was provided. Results of the tests are presented in Fig. 3.7. The friction
angle between the smooth HOPE sheet and Bentomat® was 13.5°.
3.3.2 Hydraulic Properties
J & L Testing Company (1990b) conducted flexible-wall permeability tests on 6-in.
(150-mm) diameter samples of Bentomat® containing either untreated granular bentonite
20
-------
Weights
Sand
Sliding
Surface
Geonet
HOPE
Hydrated
Bentomat®
Fastener
HOPE
Base
Figure 3.6. Schematic Diagram of Tilt Table Tests (J & L Testing Company, 1990a).
100
co
Q.
CO
CO
CD
CO
0)
.c
co
1 00
200
300
400
Normal Stress (psf)
Figure 3.7. Results of Tilt Table Tests on Bentomat® (J & L Testing Company, 1990a).
21
-------
("CS" grade) and high-contaminant-resistant bentonite ("SS" grade). Test conditions and
results are summarized in Table 3.2. The duration of the tests was not reported. Figure 3.8
presents the relationship between hydraulic conductivity and maximum effective stress.
Hydraulic conductivities ranged from 6 x 10~10 cm/s to 6 x 10~9 cm/s.
3.3.3 Seams
There have been no test results reported on the performance of Bentomat® seams.
Bench-scale hydraulic conductivity tests on seam overlaps are in progress at the University of
Texas at Austin, but no results were available at the time of this writing.
3.3.4 Mechanical Properties
Tests measuring grab strength, elongation, Mullen burst strength, wide width tensile
strength and other mechanical properties of Bentomat® were conducted by J & L Testing
Company, Inc. Tests were conducted according to ASTM standards, where available, on dry and
hydrated Bentomat® as well as on the individual woven and nonwoven geotextile components of
the liner material. Results of the test are summarized in Tables 3.3 through 3.6. Some
slippage of the mat occurred on wide-width tensile testing. Tests will be repeated with modified
grips.
3.4 Examples of Use
Bentomat® has been used in landfills, industrial and decorative lagoons, and as
secondary containment liners in tank farms. However, because of its recent release in January,
1990, the applications of Bentomat® have been limited.
The largest Bentomat® installation to date in the U.S. was a lake liner for a residential
development. A 9-acre (3.6 ha) lake was designed to be built in the midst of homes in the Cove
on Herring Creek development in Delaware. Due to the existence of poor quality native soils,
standing water, steep slopes and rough subgrade, the developer selected Bentomat® to line the
lake. The liner was placed through water and over soft subgrade by placing each panel and then
immediately following with a backhoe to place a foot of protective soil over the installed liner.
The lake was filled in June, 1990.
A contaminant-resistant grade of Bentomat® ("PL" bentonite, which contains a
polymer) was installed as a secondary containment barrier for petroleum tanks at a site in
Oklahoma. Approximately 8400 ft2 (780 m2) of liner material was installed. Lysimeters
were placed prior to all installations and the impoundments were flooded prior to their use to
22
-------
Table 3.2 Summary of Results of Hydraulic Conductivity (K) Tests on Bentomat®
(J&L Testing Company, 1990b)
Grade of Bentonite
High-Contaminant-
Resistant ("SS")
Untreated Granular
Bentonite ("CS")
-V)
E
^
>>
-*—»
'>
-*—»
o
13
o
O
o
"5
co
10
-8
10
-9
10
-10
Stress
(DSH
Maximum
Cell Headwater Tailwater Effective
50 42.2 41.8 8.2
50 44.6
50 47.2
50 42.2
50 44.6
50 47.2
• " 1 "
• Bentomat CS
• Bentomat SS
Hydraulic
Conductivity
(cm/s}
2.1 x 10-9
39.4 10.6 7.5 x 10'10
36.8 13.2 5.8 x 10'10
41.8 8.2 5.6 x 10-9
39.4 10.6 1.1 x ID'9
36.8 13.2
W;
iiii
9.8 x 10-10
1 2
1 6
Max. Effective Confining Stress (psi)
Figure 3.8. Results of Flexible-Wall Hydraulic Conductivity Tests on Bentomat® (J&L
Testing Company, 1990b).
23
-------
both activate the bentonite and check for defects. No leaks were apparent through the
Bentomat® during this test.
Bentomat® has been installed in only one municipal landfill to date. A berm that was
built across the center of a large landfill cell was lined with 20,000 ft2 (1900 m2) of
Bentomat®. To insure the liner material would seal against an HOPE liner, granular bentonite
was used at the HDPE/Bentomat® interface. The "PL" contaminant-resistant grade of
Bentomat® was used on this project.
24
-------
Table 3.3 Physical Property Test Results: Dry Bentomat® Containing High-Contaminant-Resistant Bentonite
(J&L Testing Company, 1990a)
ro
en
TEST
GRAB STRENGTH
MD-lnitial Peak
MD-Secondary Peak
GRAB ELONG.
MD-lnitial Peak
MD-Secondary Peak
MULLEN BURST
TRAPEZOIDAL TEAR
PUNCTURE
WIDE WIDTH
TENSILE
INTERGEOTEXTILE
SHEAR
INTERGEOTEXTILE
PEEL
ASTM
D-4632
D-4632
D-3786
D-4533
D-4833
D-4595
D-3083(1)
0-413(1)
UNITS
Ibs
%
psl
MD/lbs
CD/lbs
Ibs
MD/lbs
Ibs/in
Ibs/in
REPLICATE NO.
1
96.9
125.1
9.3
102.7
270
64.9
62.4
71.7
316.5
17.2
6.6
Sep.(2)
2
79.4
N/A
12.0
N/A
300
44.3
61.5
90.9
317.3
; /.e
5.7
Sep.(2)
3
90.3
96.7
11.7
125.7
324
51.5
48.0
78.1
339.8
22.1
4.4
Sep.(2)
4
92.6
134.9
15.0
141.7
333
50.7
75.9
126.4
293.1
26.0
2.4
Sep.(2)
5
99.0
100.9
14.7
110.0
395
63.5
77.9
131.3
345.5
27.9
7.4
Sep.(2)
AVERAGE
91.64
114.40
12.54
120.03
324.4
54.98
65.13
99.68
322.44
22.16
5.30
STD DEV
6. 846
16.049
2.108
15.022
41.505
7.943
10.901
24.655
18.739
4.315
1.760
NOTES: (l)lniergootextile shear and peel performed using 4 inch wide specimens.
(2)Scam separated completely during lest.
-------
Table 3.4 Physical Property Test Results: Hydrated Bentomat® Containing High-Contaminant-Resistant Bentonite
(J&L Testing Company, 1990a)
ro
01
TEST
GRAB STRENGTH
GRAB ELONG.
MULLEN BURST
TRAPEZOIDAL TEAR
PUNCTURE
WIDE WIDTH
TENSILE
INTERGEOTEXTILE
SHEAR
INTERGEOTEXTILE
PEEL
ASTM
0-4632
D-4632
D-3786
D-4533
D-4833
D-4595
D-3083(1)
D-413(1)
UNITS
Ibs
%
psl
MD/lbs
Ibs
MD/lbs
IbsJin
Ibs/in
REPLICATE NO,
1
88.6
26.7
130
44.6
35.9
276.8
42.0
13.4
Sep.(2)
2
82.5
25.0
120
59.6
39.6
238.1
49.1
Sep.(2)
14.0
Sep.(2)
3
84.7
23.3
75
51.5
38.0
288.2
67.0
20.6
Sep.(2)
4
87.1
21.7
135
51.0
39.9
295.7
49.1
Sep(2)
11.9
Sop.(2)
5
103.0
30.0
145
73.5
32.4
264.2
46.0
Sop.(2)
8.9
Sep.(2)
AVERAGE
90.86
25.43
121.0
56.02
37.15
272.58
50.63
13.74
Sep.(2)
STD DEV
7.147
3.200
24.372
9.932
2.785
20.260
8.584
3.835
NOTES: (l)lnlergeolextile shear and peel performed using 4 Inch wide specimens.
(2)Seam separated completely during test.
-------
Table 3.5 Physical Property Test Results for NonWoven Geotextile Component of Bentomat® (J&L Testing Company, 1990a)
l\5
TEST
GRAB STRENGTH
GRAB ELONGATION
MULLEN BURST
TRAPEZOIDAL TEAR
PUNCTURE
WIDE WIDTH
TENSILE
ASTM
D-4632
D-4632
D-3786
D-4533
D-4833
D-4595
UNITS
MD/lbs
MD/%
psl
MD/lbs
Ibs
MD/lbs
REPLICATE NO.
1
75.2
188.4
162
34.6
54.0
297.9
2
56.2
120.0
173
45.1
49.2
256.8
3
104.6
126.6
218
39.2
25.0
129.1
4
69.5
116.6
178
31.2
42.4
134.6
5
75.2
175.0
192
13.2
36.9
121.0
AVERAGE
76.14
145.32
184.6
32.66
41.49
187.88
STD DEV
15.833
30.177
19.283
10.790
10.085
74.325
-------
Table 3.6 Physical Property Test Results for Woven Geotextile Component of Bentomat® (J&L Testing Company, 1990a)
ro
CD
TEST
GRAB STRENGTH
GRAB ELONGATION
MULLEN BURST
TRAPEZOIDAL TEAR
PUNCTURE
WIDE WIDTH
TENSILE
ASTM
D-4632
D-4632
D-3786
D-4533
D-4833
D-4595
UNITS
MDflbS
MD/%
psi
MD/lbs
Ibs
MD/lbs
REPLICATE NO.
1
151.4
20.0
175
69.6
9.2
524.1
2
152.4
23.3
326
62.2
12.4
576.9
3
145.9
23.8
352
62.4
13.3
555.3
4
147.8
22.5
340
67.7
16.0
588.4
5
166. 6
21.7
343
72.4
11.0
657.8
AVERAGE
152.82
22.26
307.2
66.86
12.38
580.50
STD DEV
7282
1.337
66.626
4.013
2.279
44.422
-------
Section 4
Claymax®
4.1 Description
Claymax® is manufactured by the James Clem Corporation, 444 North Michigan, Suite
1610, Chicago, Illinois 60611 (telephone 312-321-6255). The material is a flexible mat
consisting of granular sodium bentonite sandwiched between two geotextiles (Fig. 4.1). The
primary backing, or top geotextile, is a slit-film, woven, polypropylene geotextile. The
polypropylene geotextile typically weighs 3 oz. to 6 oz. per square yard (102 to 204 g/m2),
depending on the application, and provides durability and puncture resistance to protect and
support the system during installation. The secondary backing, or bottom layer, is usually a
spun-lace, open-weave polyester that weighs 3/4 oz. per square yard (25 g/m2), although
other materials can be substituted depending on specific requirements. The primary function of
the secondary backing is to hold the bentonite in place during installation. In addition, the open
weave of the backing allows the bentonite to expand when it hydrates and to ooze out between the
openings so that a seal is formed. Information about the geotextiles is given in Table 4.1.
Woven Polypropylene
Geotextile
Sodium
with an Adhesive ##
•••• s • sV%V% . •. . s . s • v •
• «» "• « • • «
r
. •. . \ . s • «. . «, • % • •. . s* s • v
• • "• "• • •
1 ' ' ' I ' ' ' ' ' I
Secondary
Backing
Figure 4.1 Schematic Diagram of Claymax'5
29
-------
Table 4.1 Material Specifications (Supplied by Manufacturer)
(A) Primary Polypropylene
Substrate
Tensile Strength (ASTM D4632)
Burst Strength (ASTM D378G)
Puncture Strength (ASTM D3787 mod.)
Elongation (ASTM D4632)
Non-Biodegradable, Non-Toxic, Porous, Woven,
Slit-Film, Polypropylene Geotextile
78 Ibs. per inch (1,390 kg/m) minimum
250 psi (1720 kPa)
70 Ibs (32 kg)
15%
(B) Secondary Backing
Description
Highly porous, non-structural, non-woven fabric
that protects and contains the granular bentonite
during installation
(C) Bentonite
Material
Gradation of Bentonite
Amount of Bentonite
Final Moisture Content
Minimum Volumetric Increase
(ASTM E946-83)
Minimum Swell Index
(USP NF XVII, "Bentonite Swelling
Power")
Gradation of Raw Bentonite
Natural Sodium Bentonite Containing a minimum of
90% Montmorillonite
Two gradations: 6 Mesh and 16 Mesh Granules
Minimum of 1 Ib/ft2 (4.9 kg/m2) Measured at
Final Moisture Content
15 to 18% (Typical)
900%
25 ml
30
-------
Sandwiched between the two geotextiles is 1 Ib per square foot (4.9 kg/m2) of sodium
benton'rte adhered to the geotextiles with a water soluble, non-toxic, organic adhesive. The
sodium bentonite consists of a minimum of 90% montmorillonite and is specially graded to have
fine grained and coarse grained granules. Claymax® is manufactured in sheets that measure
approximately 1/4 in. (6 mm) in thickness, 13.5 ft (4.1 m) in width, and 100 ft (30.5 m) in length. The
sheets are placed on rolls, each of which weighs approximately 1400 Ibs (635 kg).
4.2 Installation
The following discussion details the installation procedures recommended by the
manufacturer. Before installation, the surface should be prepared by removing all angular
rocks, roots, grass, vegetation, and foreign materials or protrusions. All cracks and voids
should be filled. The surficial soils should be compacted to at least 90% of modified Proctor
density (ASTM D1557). The prepared surface should be free from loose earth, fully-exposed
rocks larger than 3/4 in. (19 mm) in diameter, rubble, and other foreign matter.
Claymax® is rolled out with the polypropylene side facing upward and with adjoining
rolls overlapping at least 6 in. (150 mm). No soil should be between the rolls in the
overlapped area. In hot, arid conditions, shrinkage may occur soon after placement; to account
for shrinkage, the longitudinal seam overlap should be increased to 9 in. (230 mm) and the
transverse overlaps increased to 4% of the run length plus 6 in. (150 mm). Seams should run
up and down a slope and never horizontally on slopes. Claymax® should not be installed in rain
or standing water; the material must be dry when installed and when covered. The liner should
be installed in a relaxed condition and should be free of tensile stress upon completion of the
installation. The liner may be pulled tight to smooth out creases or irregularities but should
not be stretched to force the liner to fit.
In windy areas, installation should commence at the upwind side of the project area. The
leading edge of the liner should be secured with sandbags or other means to hold the material in
position during installation. Only material that can be anchored and covered in the same day
should be unpackaged and placed in position. A trench should be used at the top of all slopes to
lock the liner in place by placing the end of the roll of Claymax® in the trench and backfilling
it. Irregular shapes or areas to be patched should be covered with sufficient material to provide
a 6-in. (150 mm) overlap in all directions. Patch repairs should not be allowed on slopes
steeper than 10%.
Claymax® must be protected from ultraviolet light and unrestrained hydration by
covering the material with a geomembrane and/or by placing 6 to 12 in. (150 to 300 mm) of
backfill or aggregate on top of Claymax®. If backfill is used, it should be compacted with
31
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wheeled rollers. Sheepsfoot compactors should not be used since the feel on the roller might
damage the Claymax®.
4.3 Properties
4.3.1 Shear Strength
Geoservices Consulting Engineers (1989a) performed three sets of direct shear tests on
selected Claymax® interfaces for the James Clem Corporation. The purpose of the tests was to
evaluate internal shearing and frictional characteristics of fully-hydrated Claymax® placed
against a silty sand and a smooth polyvinyl chloride (PVC) geomembrane. The tests were
performed in 12-in. by 12-in. (300 mm by 300 mm) direct shear boxes which consisted of,
from top to bottom: (1) a layer of silty sand soil, dense sand, or, dense sand and 40 mil (1.0
mm) PVC geomembrane, depending on the specific test being conducted; (2) Claymax® that had
been fully hydrated for 24 hours under 500 psf (24 kPa) normal stress; and (3) a layer of
dense sand. Vertical stresses ranging from 100 to 575 psf (5 to 24 kPa) were used, and
shearing took place at a rate of 0.02 in/min (0.5 mm/min) with the upper half of the shear box
in motion and the lower half fixed. Failure was forced through the bentonite layer for one series
of tests; for the other series, failure was forced through the contact between the Claymax® and
the overlying material (PVC geomembrane or silty sand). It appears that the rate of shearing
may have been too rapid for long-term, fully-drained conditions to have been ensured.
Mohr-Coulomb diagrams are shown in Figs. 4.2, 4.3, and 4.4 for Claymax®,
Claymax®/PVC, and Claymax®/sand, respectively. Results of the tests are summarized in
Table 4.2. The friction angles were 12° for Claymax® alone, 15° for Claymax®/PVC, and 17°
for Claymax®/sand.
Chen-Northern (1988) performed direct shear tests on the bentonite layer of samples
of saturated Claymax® for a uranium mill tailings remedial action project (UMTRA) in
Durango, Colorado. Two consolidated-undrained tests and two consolidated-drained tests were
performed by applying strain rates of 0.047 and 0.00013 in/min (1.1 and .003 mm/min),
respectively, under normal stresses of 3, 6, and 12 psi (20.7, 31.3, and 82.7 kPa). The test
specimens were allowed to hydrate for 2 to 3 days prior to shearing. Results are plotted in Figs.
4.5 and 4.6 for undrained and drained tests, respectively. One data point for the consolidated-
undrained tests was left off of Fig. 4.5 because the point was inconsistent with the overall trend
of data (beyond the ordinary limits of variability of test data). The cohesion and friction angles
computed by least-squares regression are summarized in Table 4.3. With undrained conditions,
Claymax® had an average angle of internal friction of 16°. When sheared under drained
conditions, Claymax® samples had an angle of internal friction of 14° and negligible cohesion.
32
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CO
Q.
CO
CO
£
-*—*
CD
CO
0)
_c
CO
0.5
0.4
0.3
0.2
0.1
0.0
c = 0.03 psi, Phi = 12 degrees
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8
Normal Stress (psi)
Figure 4.2. Mohr-Coulomb Failure Envelope for Direct Shear Tests Performed on Hydrated
Bentonite with Shear Plane Passing through the Bentonite within Claymax®
(Geoservices, 1989a).
CO
Q.
to
CO
CO
TO
CO
c = 3.4 psi, Phi = 15 degrees
01234567
Normal Stress (psi)
Figure 4.3. Mohr-Coulomb Failure Envelope for Direct Shear Tests Performed on Hydrated
Bentonite with Shear Plane Passing through the Interface between Polypropylene
Geotextile on Claymax® and a 40-mil PVC Geomembrane (Geoservices, 1989a).
33
-------
CO
Q.
CO
CO
CD
CO
v_
CO
CD
x:
CO
c = 3.9 psi, Phi = 17 degrees
2345
Normal Stress (psi)
Figure 4.4. Mohr-Coulomb Failure Envelope for Direct Shear Tests Performed on Hydrated
Bentonite with Shear Plane Passing through the Interface between Polypropylene
Geotextile on Claymax® and a Silty Sand (Geoservices, 1989a).
Table 4.2 Summary of Results of Direct Shear Tests on Claymax® (Geoservices, 1989a)
Sample
Cohesion
(DSfl
Friction Angle
(degrees)
Hydrated Claymax® Alone
1 2
Hydrated Claymax® Against PVC
Hydrated Claymax® Against Silty Sand
490
560
1 5
1 7
34
-------
in
CD
^.
^—»
co
CO
CD
-C
CO
10
8
6
!c = 1.8 psi, Phi = 16 degrees
8 10 12 14
Normal Stress (psi)
Figure 4.5. Results of Consolidated-Drained Direct Shear Tests on Claymax® (Chen
Northern, 1988).
in
a.
in
cp
-*—•
CO
CO
0>
_c
CO
c = 0.28 psi, Phi = 14 degrees
0 2 4 6 8 101214
Normal Stress (psi)
Figure 4.6. Results of Consolidated-Drained Direct Shear Tests on Claymax® (Chen
Northern, 1988).
35
-------
Table 4.3 Results of Direct Shear Tests on Claymax® (Chen-Northern, 1988)
Cohesion Friction Angle
Drainage Conditions (psf) (degrees)
Consolidated-Undrained Conditions 260 16
Consolidated-Drained Conditions 40 14
Direct shear tests were also conducted by Shan (1990). Consolidated-drained tests
were conducted on 2.5-in. (64-mm) diameter samples of both dry and fully saturated
Claymax® with constant strain rates of 0.63 and 0.0008 in. per hour (16 and 0.02 mm/hr),
respectively The soaking period was typically 2 to 3 weeks and the time to failure was
approximately 3 to 5 days for the saturated Claymax®. The rate of shearing used by Shan
(1990) appears to have been slow enough to ensure fully-drained failure. Normal stresses
ranged from 575 to 2880 psf (28 and 138 kPa). Results are summarized in Table 4.4. The
Mohr-Coulomb diagrams are shown in Figs. 4.7 and 4.8 for dry and hydrated bentonite,
respectively. The internal angle of friction was found to be 28° for the dry Claymax®, and 9°
for the hydrated Claymax®.
Table 4.4 Results of Direct Shear Tests on Claymax® (Shan, 1990)
Cohesion Friction Angle
Hvdration Condition (psf) (degrees)
Dry Bentonite 550 28
Hydrated Bentonite 90 9
36
-------
20
¥ 16
Q.
03
CO
CD
L-
••—'
CO
1_
CO
CD
jr
CO
12
8
4
c = 3.8 psi Phi = 28 degrees
10 15 20
Normal Stress (psi)
25
Figure 4.7. Results of Direct Shear Tests on Dry Samples of Claymax® (Shan, 1990).
0. 3
CO
CO
CD
CO
v_
03
0)
-C
CO
c = 0.6 ps Phi = 9 degrees
1 0 20
Normal Stress (psi)
30
Figure 4.8. Results of Direct Shear Tests on Hydrated Samples of Claymax® (Shan, 1990).
37
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4.3.2 Hydraulic Properties
4.3.2.1 Tests with Water
Literature published by the James Clem Corporation lists 2 x 10~10 cm/s as the
hydraulic conductivity of Claymax® permeated with deaired water. A summary of published
measurements of the hydraulic conductivity of Claymax® to water is given in Table 4.5.
Results are plotted in Fig. 4.9 in terms of hydraulic conductivity versus effective confining
stress. The results show that the hydraulic conductivity to water varies from just under about
1 x 10~8 cm/s at low effective stress to just above 1 x 1(T10 cm/s at high effective stress.
Estornell (unpublished) permeated an 8 ft by 4 ft (2.4 m by 1.2 m) piece of Claymax®
in a large tank, which is described more fully in Section 4.3.3. This data point is also shown in
Fig. 4.9 and is similar, though slightly larger than, the trend of the other data.
10
-8
o
^
XJ
c
O
O
o
10
-9
10
-1 0
Q Chen-Northern (1988)
• Geoservices (1988a)
• Geoservices (1889d)
x Shan (1990)
<• Shan (Unpub.)
n Estornell (Unpub.)
1 0
1 00
Effective Confining Stress (psi)
Figure 4.9 Results of Hydraulic Conductivity Tests on Claymax® Permeated with Water.
38
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Table 4.5 Results of Hydraulic Conductivity Tests on Claymax® Permeated with Water
CO
to
Source of Information
Clem Corp. Literature
Chen-Northern (1988)
Geoservices (1988a)
Geoservices (1989d)
Geoservices (1989d)
Geoservices (1989d)
Geoservices (1989d)
Shan (1990)
Shan (1990)
Shan (1990)
Shan (1990)
Shan (1990)
Shan (1990)
Shan (Unpub.)
Permeameter
Flex.
Flex.
Flex.
Flex.
Flex.
Flex.
Flex.
Flex.
Flex.
Flex.
Flex.
Flex.
Flex.
Wall
Wall
Wall
Wall
Wall
Wall
Wall
Wall
Wall
Wall
Wall
Wall
Wall
Backpressure Diameter of
Saturation? Permeant Water Sample (in.)
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
No
Yes
Deaired Water
- -
Deaired Tap Water
Deaired Tap Water
Deaired Tap Water
Deaired Tap Water
Deaired Tap Water
Distilled Water
Tap Water
Distilled Water
Tap Water
Distilled Water
Distilled Water
Tap Water
2
2
2
2
2
2
4
4
4
4
4
4
1
.5
.8
.8
.8
.8
.8
.0
.0
.0
.0
.0
.0
2
Effective
Stress (psi)
3.5
2
3
3
3
3
2
2
5
5
1
2
2
9
0
0
0
0
0
0
Hydraulic
Conductivity
(cm/s)
2
2
4
8
8
3
7
2
2
1
8
6
3
2
X
X
X
X
X
X
X
X
X
X
X
X
X
X
10-
10
10-
10-
10-
10-
10"
10
10
10
10-
10"
10-
10
-9
10
10
10
10
10
-9
-9
-9
10
10
10
10-9
-------
•... . i ....UUlJ.KalHi
4.3.2.2 Various Liquid and Chemical Leachates
The information available concerning hydraulic conductivity of Claymax® permeated
with liquids other than water is summarized in Table 4.6. All of the test specimens that were
hydrated with water and then permeated with chemicals maintained a hydraulic conductivity < 1
x 10"8 cm/s, even for compounds such as diesel fuel and heptane that would normally be very
aggressive to soil liner materials. Brown, Thomas, and Green (1984), for example, found that
the hydraulic conductivity of a compacted, micaceous soil was 1 to 4 orders of magnitude higher
to kerosene, diesel fuel, and gasoline than it was to water. The inconsistency of results reported
in Table 4.6 to the research conducted by Brown and his co-workers may be related to either a
small cumulative pore volumes of flow in the tests on Claymax® or application of a high
compressive stress to the test specimens. The cumulative pore volumes of flow of permeant
liquid was not reported in many of the test referenced in Table 4.6; in many cases, there was
probably an insufficient quantity of flow to determine the full effects of the permeant liquids.
In some tests, a large effective confining stress was used. Broderick and Daniel (1990) found
that one compacted clay was vulnerable to significant alterations in hydraulic conductivity when
compressive stresses were < 5 - 10 psi (34 - 69 kPa) but did not undergo an increase in
hydraulic conductivity when the specimens were permeated with comoressive stresses larger
than 5 to 10 psi (34 to 69 kPa). Brown and his co-workers appliec no compressive stress to
their test specimens.
Tests on specimens of Claymax® that were hydrated with the same liquid as the eventual
permeant liquid (rather than water) showed mixed results. For leachates, a paper pulp sludge,
and simulated seawater, the hydraulic conductivity was found to be < 1 x 10~9 cm/s. However,
the significance of these results is questionable because the duration of the tests was short, the
cumulative pore volumes of flow was not reported, and the applied compressive stress was not
reported. In as-yet unpublished tests by Shan, markedly different results were obtained when
Claymax® was not prehydrated with water. Shan found that when dry Claymax® was permeated
directly with a 50% mixture of water and methanol, with pure methanol, or with heptane, the
bentonite did not hydrate even after several pore volumes of flow, and the hydraulic
conductivity did not drop below 1 x 10'6 cm/s. Shan used a compressive stress of 5 psi (34
kPa). Thus, with concentrated organic liquids, the conditions of hydration appear to play an
important role in determining the ability of the bentonitic blanket to resist the deleterious
action of organic chemicals. The bentonite appears to be more chemically resistant if hydrated
with fresh water before exposure to concentrated organic chemicals.
40
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Table 4.6 Hydraulic Conductivity of Claymax® Permeated with Various Liquids
Source of Information
STS Consultants (1988b)
STS Consultants (1988c)
Geoservices (1988b)
STS Consultants (1989a)
STS Consultants (1989b)
Geoservices (1989d)
Geoservices (1989d)
Geoservices (1989d)
Geoservices (1989d)
Shan (1990)
Shan (1990)
Shan (1990)
Shan (1990)
Shan (1990)
Shan (Unpublished)
Shan (Unpublished)
Shan (Unpublished)
Permeant Liquid
Sewage Leachate
Paper Pulp Sludge
Simulated Seawaler
Landfill Leachate
Ash-Fill Leachate
Diesel Fuel
Jet Fuel
Unleaded Gasoline
Gasahol
50% (Vol) Methanol
Heptane
Sulfiric Acid
0.01 N CaSO4
0.5 N CaCl2
50% (Vol) Methanol
Methanol
Heptane
Hydration Liquid
Sewage Leachate
Paper Pulp Sludge
Simulated Seawater
Landfill Leachate
Ash-Fill Leachate
Water
Water
Water
Water
Water
Water
Water
Water
Water
50% Methanol
Methanol
Heptane
Pore Volumes
of Flow
- -
- -
- -
- -
1.5
2.5
1.6
0.5
2.2
0.2
3.1
2.2
24
4
5.4
4.3
Effective
Confining Stress
(psi)
- -
30
- -
- -
30
30
30
30
5
5
5
5
5
5
5
5
Hydraulic
Conductivity
(cm/sec)
8 x 10'10
2 x 10-10
2 x 10'10
4 x 10'10
1 x 10'10
9 x 10'10
9 x 10-10
3 x ID'10
3 x ID'10
9 x 10'10
1 x 10'10
6 x 10'11
1 x 10'9
8 x 1C-9
5 x 10'6
3 X 10-5
5 x 10-5
-------
4.3.2.3 Effects of Desiccation
The effects of desiccation were investigated by Geoservices (1989e). Three hydrated
samples of Claymax® were placed in a temperature- and humidity-controlled chamber. The
chambers operated on a timed cycle to simulate day and night conditions. The temperature and
humidity during the day cycle were 95°F and 30%, respectively, while the temperature and
humidity during the night cycle were 70°F and 50%, respectively. Samples of Claymax® were
buried below 8 in. (200 mm) and 18 in. (450 mm) of sand, while a third sample was not
buried beneath any sand. Water content samples were obtained from the Claymax® regularly
throughout the 3-month test period.
Results of the Geoservices tests are summarized in Table 4.7. The Claymax® sample left
exposed with no sand overburden underwent severe drying. In comparison, little or no
desiccation appeared to have occurred during the testing period when Claymax® was buried
beneath sand. The sand appeared to provide an adequate buffer to the extremes of temperature
and humidity to protect the Claymax® from desiccation.
Table 4.7 Results of Desiccation Studies on Sand Overlying Claymax® (Geoservices, 1989e)
Depth Below Water Content (%}
Top of Sand (in.) Elapsed Time (Days): 0 4 21 25 47 90
0 1300 690 15 - 6 1
8.5 260 - - - - 280 - - 260
18.5 300 - - - - 265 - - 248
Shan (1990) studied the effects of desiccation on the hydraulic properties of Claymax®
in a different way. Shan measured the hydraulic conductivity of 4-in (100-mm) diameter
samples .of Claymax® that had been subjected to several wet-dry cycles. His experiment
42
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involved permeating Claymax® specimens in a flexible-wall permeameter using an effective
stress of 2 psi (14 kPa) and a hydraulic gradient of about 50. The specimens were then
removed from the permeameter and allowed to air dry. At first the specimens were dried on a
laboratory table top with no overburden, but the specimens shrank to much smaller-diameter
circular discs and did not undergo significant cracking. To force desiccation cracks to develop, a
vertical stress of about 0.2 psi (1 kPa) was applied to the specimens while they dried. The
stress was applied by placing a steel cylinder on top of the sample to be desiccated. Numerous
large (2-mm-wide) desiccation cracks were seen in the dried specimens that had the small
overburden stress. The desiccated specimens containing cracks were set up again in a flexible-
wall permeameter and were permeated under the same conditions. After permeation, the
specimens were removed and desiccated/permeated again. It was found that after 3 wet-dry
cycles, the hydraulic conductivity of Claymax® did not change; it remained approximately 2 x
10'9 cm/s. Shan reported that at the beginning of repermeation after drying, the hydraulic
conductivity was on the order of 10~4 cm/s as water flowed through the cracks very easily.
But the cracks closed within a few hours and the flow stopped as bentonite hydrated and took in
water from both influent and effluent ends. It was not until bentonite was fully hydrated that
flow started again.
Chen-Northern (1988) conducted hydraulic conductivity tests in flexible-wall
permeameters on samples of Claymax® that had undergone 0, 3, and 10 cycles of wetting and
drying. The hydraulic conductivity increased approximately 2.6 times after three cycles of
wetting/drying but underwent no further increase with additional wet/dry cycles. Hydraulic
conductivities were 1 x 10'9 cm/s, 2.6 x 10'9 cm/s, and 2.3 x 10'9 cm/s, respectively, for
samples subjected to 0, 3, and 10 cycles of wetting and drying.
4.3.2.4 Hydraulic Properties of Damaged Claymax®
Hydraulic conductivity of Claymax® was measured by STS Consultants (1988a) on a
specimen of Claymax® that had been subjected to 15% elongation. The purpose of the
experiment was to study the hydraulic integrity of Claymax® after a specimen had undergone
deformation. The Claymax® specimen (evidently in a dry condition) was first stretched to 15%
elongation. A 2.5-in. (64 mm) diameter piece of the stretched Claymax® was trimmed from
the larger piece that had been stretched and was then placed above approximately 5-1/2 in.
(140 mm) of silica sand in a flexible-wall permeameter. The test specimen was hydrated,
saturated, and permeated with de-aired water. The effective consolidation stress was 0.15
kg/cm2 (125 kPa) and the backpressure was 4.0 kg/cm2 (392 kPa). The test was allowed to
continue until steady state was reached. The hydraulic conductivity of the material that had been
43
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subjected to a 15% elongation was determined to be 4 x 1CT10 cm/s. Elongation appeared to
have a negligible effect upon the hydraulic characteristics of the material.
The effects of punctures on the hydraulic conductivity of Claymax® was investigated by
Shan (1990). Punctures were simulated by cutting three holes, each 0.5, 1.0, or 3.0 in. (13,
25, or 75 mm) in diameter, in dry Claymax® specimens. The specimens were permeated with
tap water in a flexible-wall permeameter under an effective stress of 2 psi (14 kPa) and a
hydraulic gradient of about 50. The test specimens that had been punctured with holes 0.5 and
1.0 in. (13 and 25 mm) in diameter had hydraulic conductivities of 3 x 10'9 and 5 x 10"9
cm/s, respectively, which is only slightly larger than the value of 2 x 10~9 cm/s measured on
an intact specimen. With the specimen containing 3 holes each 3-in. (75 mm) in diameter, 2
of the 3 holes did not seal themselves and were left with openings of about 0.5 in. (13 mm) in
diameter. These tests, in conjunction with the tests on desiccated specimens, demonstrate that
the swelling nature of bentonite gives this material the capability of self-healing small defects
or punctures when the material is hydrated with water.
4.3.2.5 Composite Action
Shubert (1987) described various tests on composites of Claymax® placed adjacent to
defective HOPE geomembrane liners. In the first series of tests, Claymax® was placed between
two defective HOPE sheets in a configuration that simulated the usage of the material at a landfill
in the Chicago area. The four separate tests, the upper and lower HOPE sheet were slit over a
length of 1 in. (25 mm) with razor blade or punctured with a large nail, but the Claymax® was
left intact. The composites were tested in a flexible-wall permeameter with a maximum
effective confining stress of 30 psi (207 kPa). Leachate from a hazardous waste landfill was
used as the permeant liquid and was pressurized with 10 psi (69 kPa) to induce permeation
into the Claymax®. No inflow or outflow was recorded after initial pressurization of the system
over the 3-day test duration.
A second series of tests is described by Shubert (1987). Three samples were tested:
Sample 1: Top HOPE: punctured with 0.84-in. (21 mm) diameter hole
Bottom HOPE: punctured with 16-penny nail
Sample 2: Top HOPE: punctured with 0.84-in. (21 mm) diameter hole
Bottom HOPE: Slit with razor blade for 1 in. (25 mm) length
Sample 3: Top HOPE: punctured with 0.84-in. (21 mm) diameter hole
Bottom HOPE: punctured with 0.84-in. (21 mm) diameter hole.
44
-------
Test conditions were the same as in the first series of tests. After 5 days of permeation, the
quantity of inflow was 1.6, 0.8, and 0.8 ml for Samples 1, 2, and 3, respectively. Visual
observations after the tests revealed that the bentonite was significantly wetted near the
proximity of each membrane defect. The wetting of the bentonite, in turn, is reported to have
caused significant swelling of the bentonite, which caused plugging of the defect.
A third series of experiments was conducted on two samples that had holes of 0.84 in.
(21 mm) diameter drilled into the top and bottom HOPE sheets. Hazardous waste landfill
leachate was introduced under the same testing conditions described earlier. The "apparent"
hydraulic conductivities of the samples were approximately 1 x 10'9 cm/s after more than
100 pore volumes of flow. A control test on Claymax® alone was not performed.
Shan (1990) conducted a test using a flexible-wall permeameter in order to measure
the in-plane hydraulic conductivity of Claymax® in contact with two sheets of high density
polyethylene (HOPE). The test set-up is shown in Fig. 4.10. The effective confining stress was
2 psi and a head of water of 1 ft was applied to one end of Claymax®. No outflow occurred for
about 2 months. When steady flow was finally reached, the computed hydraulic conductivity was
2 x 10'6 cm/s. At least some seal was obtained between the Claymax® and the HOPE because
there was no outflow for two months. However, in view of the high in-plane conductivity, the
seal was evidently imperfect.
Shan (unpublished) permeated 3 samples of 12-in. (300-mm) diameter Claymax® in
flexible-wall permeameters using an effective stress of 2 psi (14 kPa) and backpressure
saturation. Two of the three Claymax® samples were overlain by a sheet of defective HOPE
sheet (the sheet was placed against the polypropylene geotextile, which would normally be the
upper geotextile in the field); the third sample was a control with no HOPE. One of the two
HOPE sheets was punctured with 3 holes, each 1 in. (25 mm) in diameter, and the second was
slit with a 1-mm-wide slit having a length of 6 in. (150 mm). The hydraulic conductivities
were as follows:
Control (No HOPE): Hydraulic Conductivity = 2 x 10~9 cm/s
Composite (3 Holes in HOPE): Hydraulic Conductivity = 4 x 10~9 cm/s
Composite (Slit in HOPE): Hydraulic Conductivity = 4 x 10'9 cm/s
It is not known why the hydraulic conductivities of the composites were slightly greater than
those of the control -- the conductivities of the composites should have been less or equal to that
of the control. Nevertheless, the data do not indicate that a particularly good seal developed
between the HOPE and the bentonite. Liquid evidently spread laterally through the geotextile and
45
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(A) Control Test for Determining Baseline
Flowrate
HOPE
Claymax ®
(B) Test on Composite Action between
Claymax® and HOPE
Figure 4.10. Schematic Diagram of Test to Evaluate In-Plane Flow (from Shan, 1990).
46
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permeated a large percentage of the area of the Claymax®. Better contact might have been
achieved if the other side of the Claymax® (the side with the light-weight, spun-lace
polyester) was placed against the HOPE. This possibility is being evaluated by the authors.
4.3.3 Seams
STS Consultants Ltd. (1984) performed a hydraulic conductivity test on a 2-in. (50
mm) wide overlapped seam of Claymax®. The test arrangement is depicted in Fig. 4.11. The
specimens were placed above a 6-in. (150-mm) thick layer of silica sand in a flexible-wall
permeameter and were backpressure-saturated prior to permeation with deaired water. The
overlapped materials were hydrated and permeated from bottom to top (with flow from the
underlying sand to the Claymax®. No details on the effective compressive stress, hydraulic
gradient, magnitude of backpressure, or duration of test were given. The hydraulic conductivity
of the test materials with the overlapped seam was 7 x 10'10 cm/s using a weighted average
specimen thickness of 0.4 in. (10 mm).
Bench-scale hydraulic conductivity tests on seam overlaps are currently being
conducted at the University of Texas at Austin. The experiments are being performed in three
rectangular steel tanks, shown schematically in Fig. 4.12, that measure 8 ft (2.4 m) in length,
4 ft (1.2 m) in width, and 3 ft (0.9 m) in height. A 1/2-in. (13 mm) diameter drain hole has
been drilled at the center of the base. To conduct a test, a geotextile/geonet/geotextile composite
drainage layer is placed over the bottom of the tank (except that a 3-in. or 75 mm wide gap is
left between the drainage material and edge of the tank to accommodate a bentonite seal that seals
the material being tested to the bottom of the tank). Next, dry bentonite is placed in the 3-in.
(75 mm) wide gap left between the drainage material and the walls of the tank. The bentonitic
blanket being tested is placed over the drainage material and bentonite edge seal, with the edges
of the material going to the edges of the steel tank. Next, a 1-ft (0.3 m) or 2-ft (0.6 m) thick
layer of gravel is placed over the bentonitic blanket. The tank is slowly filled with a depth of
water above the bentonitic blanket of 1 to 2 ft (0.3 to 0.6 m). Effluent water passing through
the drain hole is collected and weighed to determine the flux of water through the material being
tested. The thickness of the material is estimated based on laboratory measurements. Hydraulic
conductivity is calculated from the measured flux and known head and known area and thickness
of the bentonitic blanket.
Tests have recently been completed on three samples of Claymax®. The tests involve:
(1) a 6-in. (150-mm) wide overlap (in accordance with the manufacturer's recommended
minimum overlap width); (2) a 3-in (75-mm) wide overlap (intended to evaluate whether the
recommended 6-in. or 150-mm wide overlap includes a generous factor of safety); and (3) a
47
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TOD View:
4 in. (100 mm)
Diameter
Side View:
2 in. (50 mm)
Sand
\
Claymax®
Figure 4.11. Schematic Diagram of Laboratory Test Designed to Evaluate the Hydraulic
Conductivity of Overlapped Seam (from STS Consultants, 1984).
48
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Steel Tank
1/2" Diameter Drain
Orthogonal View
Water
Gravel
Bentonitic Blanket
Drainage Hole
IT
Geonet/Geotextile
Drainage Layer
Bentonite Seal
Collection
Container
Cross Sectional View
Figure 4.12. Schematic Diagram of Tanks Being Used to Measure Hydraulic Conductivity of
Bentonitic Blankets Containing Overlapped Seams.
49
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control with no overlap. In the first tests, the gravel layer was 1-ft (0.3 m) thick, and the
depth of water above the Claymax® was 2 ft (0.6 m). These conditions were estimated to
produce an effective vertical stress of approximately 75 psf (3.6 kPa) at the top of the
Claymax® and 200 psf (9.6 kPa) at the bottom of the Claymax®. Steady state flow was
achieved after approximately 1.5 months, and the hydraulic conductivities were 9 x 10~9
cm/s, 2 x 10"8 cm/s, and 6 x 10~8 cm/s for the control, 6-in. (150 mm) wide seam, and 3-
in. (75 mm) wide seam, respectively. Hydraulic conductivity was calculated assuming a
thickness of 0.5 in. (13 mm) for the material based on data published by Shan (1990).
Effective overburden stress was later increased to approximately 220 psf (10.5 kPa) at the top
of the Claymax® but steady state conditions have not been reached as of this writing.
4.3.4 Swelling Characteristics
Shan (1990) measured the swelling characteristics of Claymax® as follows. A 2.5-in.
(64-mm) diameter specimen was trimmed, placed in a consolidation ring, compressed with a
controlled vertical stress, and then hydrated with water. The percentage change in height was
monitored until the sample ceased to swell or compress. The test was repeated for several
different levels of stress. Results are plotted in Fig. 4.13. The stress at which no compression
or swelling occurred was found to be approximately 3,000 psf (144 kPa).
D)
0)
IE
15
c
_
O
o
I
0)
05
d
m
-C
O
-1
1 00
1000
10000
100000
Effective Vertical Stress (psf)
Figure 4.13. Results of Swelling Tests on Samples of Claymax® (from Shan, 1990).
so
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4.4 Examples of Use
Lutz (1990) describes examples of the use of Claymax® based on information supplied
by the James Clem Corporation. The following was taken from Lutz's discussion.
The Broward County Landfill in Fort Lauderdale, Florida, is a 20 acre (8 ha)
incinerator ash monofill. County officials wanted an alternative to importing clay to construct a
liner for the landfill so they decided to use Claymax®. The components, from bottom to top, are
as follows: 6 in. (150 mm) of bedding sand; a 60 mil (1.5 mm) HOPE liner; 12 in. (300 mm)
of drainage sand; Claymax®; an 80 mil (2 mm) HOPE liner; and 24 in. (600 mm) of drainage
sand.
A 3 acre (1.2 ha) commercial hazardous waste landfill in Calumet City, Illinois,
contains a double composite liner system with a secondary leachate collection and removal
system. The components, from bottom to top, are as follows: 3 ft (0.9 m) of compacted clay; a
60 mil (1.5 mm) HOPE liner; a secondary leachate collection and removal system; Claymax®;
and a 100 mi (2.5 mm) HOPE liner. This landfill was completed in March of 1986, and there
has been no accumulation of leachate in the secondary leachate collection system.
St. Paul Island is in the Bering Sea and acts as a refueling site for fishing vessels. The
fuel storage tank farm needed to be enlarged and relocated. Since the island is a primary
breeding ground for the northern fur seal and has a large seabird population, the environmental
sensitivity of the island was a major concern. The cold, wet, and windy climate of St. Paul
Island makes construction difficult. Claymax® was used because of its ability to form a barrier
to fuel oils as well as its ease of installation. The liner was installed in sections between periods
of inclement weather. Pipe penetrations were sealed by wrapping Claymax® around the pipe at
the penetration. For tank farm applications, the Claymax® must be saturated with water after
it has been covered with the bedding material, otherwise the Claymax® will neither hydrate
properly nor impede the flow of a hydrocarbon spill.
During the open discussion session of the Alternative Barriers Workshop, Steve Walker
of Polyfelt, Inc., and John Boschuk of J & L Testing Company, Inc., described two other cases in
which Claymax® was used as a liquid barrier. A 60-acre (24 ha) ravine in the Hudson Valley
area was proposed as a site to contain PCB's. The existing subbase was a weak material
(standard penetration test N-value of 2) with organic deposits that generated gas. The
requirements for the liner were that it be impervious, collect gas, and act as reinforcement.
Instead of using compacted clay that would have been difficult to impossible to compact on the
existing subbase and would have required 22,000 truck loads of clay, a custom-made Claymax®
product was used which required only 90 tractor trailers at two-thirds the cost. The custom
made Claymax® liner was made using a 10 ounce per square yard (340 g/m2) geotextile cover
51
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fabric instead of the typical 1 ounce per square yard (34 g/m2) in order to meet the
requirements of collecting gas and providing reinforcement.
The second case involved a 5 acre (2 ha) pond at a campground. Two feet (600 mm)
below existing mudline was a layer of decomposed rock which was causing water to drain out of
the pond. Campground owners decided to line the pond with Claymax®. An anchor trench was
deemed unnecessary because the maximum side slope at the site was 12:1. A friction anchor was
used instead, consisting of 1 foot (300 mm) of soil placed above the Claymax® liner at the top
of the slope. Some time shortly after construction, a slope failure occurred. On the 16:1 (4°)
slopes, the Claymax® liner slid only a few inches; on the 12:1 (5°) slopes, the liner slid all the
way down the embankment. The sliding surface was between the geotextile and the ground
surface. It is hypothesized that movement of the slightly viscous bentonite in the Claymax®
caused slippage. It is evident from this failure that anchor trenches are important and that
more information is needed concerning the frictional characteristics of Claymax®.
In addition to the examples listed above, Claymax® liners have been used to waterproof
building foundations and to line waste lagoons and irrigation canals. Claymax® has also been
used as an alternative to cutoff walls and slurry walls and has been used as part of the core
material in a dam. This type of information is available in a series of publications supplied by
the manufacturer.
52
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Section 5.0
Gundseal
5.1 Description
Gundseal will be manufactured by the team of Gundle Lining Systems, Inc. (18100
Gundle Road, Houston, Texas 77073, telephone 713-443-8564), and Paramount Technical
Products, Inc. (2600 Paramount Drive, Spearfish, South Dakota 57783, telephone 605-642-
4787). The manufacturing facility will be located in Spearfish, South Dakota. Gundseal will be
similar to an existing product, Paraseal, which is manufactured by Paramount Technical
Products, Inc. Paraseal consists of one pound per square foot (4.5 kg/m2) of sodium bentonite
glued to a 20 mil (0.5 mm) HOPE geomembrane (Fig. 5.1), although the liner can be
manufactured with other thicknesses of HOPE. Paraseal can be supplied with or without a
light-weight fabric backing, which helps to prevent spalling of small granules of bentonite.
Paraseal is manufactured in 24-ft (7.3 m) long by 4-ft (1.2 m) wide rolls. Paraseal can be
installed with the HOPE facing upward or downward. The material is available with different
grades of bentonite, depending upon whether the bentonite is to retain fresh water or saline
water. Paraseal is seamed in the field with simple overlaps; although no mechanical seam is
necessary, mechanical seaming of HOPE to HOPE is possible. To date, Paraseal has been used
primarily for waterproofing basement walls, basement slabs, water-retention structures, and
small reservoirs and ponds.
Light-Weight Fabric Backing
^'UUUUJ^.%JsUJ.%UUJ.^^%UUUUUUJ.'JflsJ%w%UJ^y|
-•gQpi^nJtg'gggggg^^
Adhesive
High-Density Polyethylene Sheet
Figure 5.1. Schematic Diagram of Paraseal and Gundseal.
53
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, . ,JULtl,
Gundseal will be composed of the same materials as Paraseal but will be produced in
rolls that are approximately 17.5-ft (5.3 m) wide and approximately 200-ft (60 m) long.
Each roll will weigh just under 4,000 Ibs (1800 kg) and will have a diameter of
approximately 3 ft (1 m). The thickness of HOPE sheet in Gundseal will initially be 20 mil
(0.5 mm), but greater thicknesses are also expected to be available. Whereas Paraseal is
intended for use primarily in structural waterproofing, Gundseal is designed for applications
involving landfill liners and covers, liquid containment ponds, waste water lagoons, tank farms,
etc. Gundle Lining Systems, Inc., anticipates utilizing Gundseal as a back-up liner for
conventional HOPE geomembrane liners. For such an application, Gundseal would be installed
with the bentonite facing upward, as shown in Fig. 5.1. A conventional geomembrane liner
would then be placed directly on the bentonite. If there are any defects in the geomembrane
liner, such as a pinhole or defective seam, the leakage through the geomembrane would be
minimized by the bentonite layer within the Gundseal.
There are no technical'data currently available on Gundseal because the product has not
yet been produced. The following section presents information about the established Parasea!
liner, which is similar to Gundseal.
5.2 Installation
The following discussion summarizes the manufacturer's fcjommended installation
procedures. The area to be covered by Gundseal or Paraseai must be graded level. All rocks,
sticks, other sharp objects and loose soil should be removed. The product can be installed with
the HOPE side facing either up or down. If used by itself as a composite liner, the HOPE would
normally face up. If the material is used to backup a geomembrane liner that is placed on top of
the Paraseal, the product is installed with the bentonite facing up.
Paraseal is unrolled and placed on the area to be covered, with adjacent rolls overlapping
at least 1.5 to 3 in. (38 to 75 mm). The material is said to be self-seaming; when the
bentonite is hydrated and swells, the bentonite/HDPE contact is hydraulically sealed. Thus, no
mechanical joining of the seams is necessary (Fig. 5.2a), although the overlapped sheets of
HOPE can be mechanically joined with a double-sided tape called Para JT® (Fig. 5.2b). Para
JT® is a proprietary adhesive joint tape compounded "om a family of partially cross-linked
polymeric elastomers. Para JT® is placed on the HOPE along a strip where the bentonite has
been removed from the edge of the roll. This configuration results in a double seal: one seal is
made by the Para JT® between two pieces of HOPE and the second between the bentonite and the
HOPE. Other methods for joining the HOPE sheets, e.g., fillet extrusion welding, could probably
54
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Overlap
(A) Overlap of Paraseal
Overlap
ParaJT^
Adhesive Joint Tape
(B) Overlap of Paraseal with Adhesive Joint Tape
Figure 5.2. Overlap of Paraseal.
55
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be employed. Paraseal should be anchored in trenches around the perimeter of the site. Upon
completion of the liner, the Paraseal must be covered with soil or other protective material.
5.3 Properties
5.3.1 Physical Properties
The physical properties of Paraseal reported by the manufacturer are summarized as
follows. The HOPE membrane has a tensile strength (ASTM D412) of 4,000 psi (27 MPa).
Elongation at failure (ASTM D638) is reported to be 700%. Puncture resistance (Federal Test
Method Standard No. 101B) is 95 IDS (43 kg). Permeance is reported to be 2.7 x 10'13
cm3/cm2 when the membrane is applied to a porous stone and placed in a permeameter with a
pressure head equivalent to 150 ft (45 m) of water.
5.3.2 Shear Strength
No information is available on the shear strength of Paraseal.
5.3.3 Hydraulic Properties
Pittsburgh Testing Laboratory (1985) conducted a hydraulic conductivity test on a 2.5-
in. (64-mm) diameter sample of Paraseal. A 15-ft (4.6-m) head of water was applied to the
sample, which was soaked for 5 days prior to permeation. A single, falling-head test was
performed, which yielded a hydraulic conductivity reported to be 4 x 10~10 cm/s. Further
details of the test procedures are not available. However, because the direction of flow was
apparently through the HOPE membrane, the test may have provided a measure of sidewall
leakage rather than flow through the material.
5.3.4 Seams
Twin City Testing Corporation (1986) measured the hydraulic conductivity of the
bentonite in overlapped pieces of Paraseal with flow taking place parallel to the HOPE sheets. A
schematic diagram of the test arrangement is shown in Fig. 5.3. Two 1 in. by 4 in. (25 by 100
mm) pieces of Paraseal were placed against one another and clamped between two half-cylinders
of lucite. The assembly was placed in a flexible-wall permeameter. The overlapped pieces of
Paraseal were compressed with a stress of 24 psi (165 kPa), hydrated under a 6-in. (150-
mm) head of water for 17 days, and permeated with a head of 40 ft (12 m) for 12 days. The
hydraulic conductivity for in-plane flow with this arrangement was 2 x 10'10 cm/s.
Bench-scale hydraulic conductivity tests on seam overlaps are currently being
conducted at The University of Texas at Austin. A description of the apparatus was given in
56
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section 4.3.3 and a diagram of the test apparatus is provided in Fig. 4.12. The three tests
currently underway on Paraseal liner are: (1) a 3-in. (75-mm) wide overlap; (2) a 1.5-in.
(38-mm) wide overlap; and (3) a control with no seam overlap. One foot (300 mm) of gravel
was placed over the Paraseal sheets, and 2 ft (0.6 m) of water was ponded on top of the sheets.
There was no outflow from any of the three test specimens over the entire 5-month testing
period.
BENTONITE BACKING SEAL
POROUS STONE
24 PSI EFFECTIVE
CONFINING PRESSURE
MEMBRANE
Figure 5.3. Schematic Diagram of Hydraulic Conductivity Test on Overlapped Seam of
Paraseal (from Twin City Testing Corporation, 1986).
57
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5.4 Examples of Use
Paraseal has been used primarily as a waterproofing material for building basements
and, to a lesser extent, to line water-retention ponds.
58
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Section 6.0
Bentofix
6.1 Description
Bentofix is manufactured by Naue-Fasertechnik Co. in Lubbecke, Germany. Information
on the material was obtained from Scheu et al. (1990) and from personal communication with
Robert M. Koerner.
Bentofix is a fiber-reinforced, bentonitic mat composed of a needlepunched, nonwoven
geotextile as a cover, bentonite as a sealing element, and a needlepunched, nonwoven geotextile
as a base layer (Fig. 6.1). The bentonite used for the manufacture of Bentofix is an activated
sodium bentonite (a calcium-bentonite modified to a sodium bentonite) containing 70%
montmorillonite. The geotextile layers are needlepunched together through the bentonite layer
with a large amount of single stitches per square inch to form the Bentofix mat (Fig. 6.1).
Granular Bentonite
Needlepunched Fibers
x ssstssss
$#&
•*•••'• ft '£***
XXXV.XXXNXXXXXX
xxxxxxxxxxxxxx
XXXXXXXXXXXXXX
'XXXXXXXXXXXXXX
Non-Woven Geotextile
Figure 6.1. Schematic Diagram of Bentofix (from Scheu et al., 1990).
6.2 Installation
Bentofix may be placed on irregular surfaces, like slightly eroded embankments and
channel beds. Larger pot holes must be filled with concrete and exposed buckles must be
removed. Joints are made by overlapping the material. An overlap width of at least 12 in.
(300 mm) is recommended. Wet granular bentonite is placed along the edge of the overlap
sheet using a "U" shaped device that applies bentonite to the overlapped section in order to
59
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increase the integrity of the seam. A ballast layer of underwater concrete or crushed stones
must be placed over the Bentofix mats in order to protect the material and keep the mats in
place. The system can be applied throughout the year without any seasonal restrictions.
Underwater installations are possible, as well.
6.3 Properties
6.3.1 Shear Strength
Direct shear tests were conducted by the Franzius Institute for Hydraulic Research and
Coastal Engineering, University of Hannover, to determine the frictional behavior of Bentofix
(Scheu et al., 1990). Bentofix specimens were placed between two sand layers in a direct shear
box. The specimens were then saturated for three days under normal stresses of 50, 100, and
200 kPa and sheared until a total displacement of approximately 30 mm had been achieved. The
time to failure was not reported by Scheu et al. Sliding took place within the bentonite layer,
which caused the needle-punched threads to align themselves according to the direction of
displacement. The Mohr-Coulomb diagram is shown in Figure 6.2. The cohesion was found to be
8 kPa (1.2 psi), and the angle of internal friction was 30°.
6.3.2 Hydraulic Properties
Hydraulic conductivity tests were carried out at the Institute for Foundation
Engineering, Soil and Rock Mechanics of the Technical University, Munich (Scheu et al., 1990).
Bentofix specimens were placed in triaxial cells, back-pressure saturated, and permeated with
de-aired water. The hydraulic conductivity of water through the Bentofix sample was
determined to be 1 x 10"^ cm/s under an unspecified effective confining stress.
6.3.3 Seams
The Franzius Institute (Scheu et al. 1990) conducted hydraulic conductivity tests on
overlapped seams and overlaps with an intermediate bentonite layer. A large box with a drain at
the bottom was used to contain the overlapped Bentofix samples. Water from an upper overflow
reservoir was fed into the box where it then permeated through the overlapped samples and
collected in a measuring glass located beneath the drain. A set of piezometer tubes were used to
measure the change in head through the sample. From these experiments, the hydraulic
conductivity of water through the Bentofix seams was determined to be 1 x 10"8 cm/s for
overlapped sections of Bentofix containing bentonite between the sheets of Bentofix. The
compressive stress applied to the overlapped area was not specified.
60
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to
Q.
CO
CO
O
-*—•
CD
CO
0
.E
CO
30
25
20
15
10
5
0
c = 1.2 psi, Phi = 30 degrees
5 10 15
Normal Stress (psi)
20
Figure 6.2 Results of Direct Shear Tests on Bentofix (from Scheu et al., 1990)
6.3.4. Mechanical Properties
Data on the mechanical properties of Bentofix could not be located.
6.4. Examples of Use
Bentofix can be used for many lining applications such as water reservoirs, channels,
artificial lakes, dams, and landfills. The installation examples cited by Scheu et al. (1990)
include a dam rehabilitation project and a chemical containment project.
The Lechkanal is a diversion canal built in the 1920's. The canal runs parallel to the
river Lech, in Germany. The weirs and locks integrated in the diversion canal are used to
generate electricity. Some portions of the 70-year-old canal are lined with man-made levees.
Surface erosion and minor piping channels have developed along sections of the levees over a
long period of time. Instability was solved using a double lining system that consisted of 140
mm of asphalt with a filter fabric drainage layer as the primary liner and Bentofix as the
secondary liner.
61
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imUBili"- " _.
A purification network was recently constructed at the Munich II Airport in Germany in
order to collect and purify the runoff from runways. Deicing of airplanes with a mixture of
glycol and hot water creates a hazardous runoff that has a potential to contaminate the
underlying groundwater. The purification network at the Munich Airport consists of
underground granular filters that support bacteria used to biologically purify the glycol and
water mixture. The sealing element between the purification system and the groundwater is
Bentofix.
62
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Section 7.0
Other Alternative Barrier Materials
Some additional barrier materials that were identified during the workshop include:
1. Flyash-bentonite-soil mixtures;
2. Super-absorbant geotextiles (e.g., Fibersorb®);
3. Sprayed-on geomembranes (intended to form a composite with a compacted soil
layer or bentonitic blanket);
4. Custom-made bentonite composites with geomembranes or geotextiles.
Fly-ash was not discussed because it did not appear to fit within the theme of thin, manufactured
materials, which was the main focus of attention at the Workshop. Few details were presented
concerning spayed-on products or custom-made bentonite composites, other than to indicate
that sprayed-on products are promising and that all of the bentonitic blankets can be custom-
designed and fabricated to meet particular needs, e.g., by using a thicker geotextile as a gas
venting medium.
Information concerning Fibersorb® was supplied via a manufacturer's brochure and a
technical report (STS Consultants, 1990). Fibersorb® is a lightweight geotextile containing
thin, nonwoven, superabsorbent fibers and is manufactured by ARCO Chemical Company (3901
West Chester Pike, Newton Square, Pennsylvania 19073, telephone 215-359-5616). When
water contacts the fibers, the resultant swelling fills voids and impedes water flow.
Fibersorb® has been used primarily in protective clothing, in packaging, filters, or humidity
control systems to seal out water or moisture, as industrial wipes, and has even been used as an
emergency heat barrier in the case of a fire due to it's heat absorption capabilities.
STS Consultants (1990) conducted constant-head hydraulic conductivity tests on 4-in.
(100-mm) diameter samples of Fibrosorb®. Four samples were tested:
Sample 1: Fibersorb® alone.
Sample 2: Fibersorb® overlying a 40 mil (1 mm) HOPE membrane that had a 1/8
in. (3 mm) diameter hole punched in it.
63
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Samples: No Fibersorb®; a 40 mil (1 mm) HOPE membrane with a 1/8'in. (3
mm) diameter hole (the membrane placed between two porous discs and
tested in the permeameter).
Sample 4: A 2-in. (50-mm) wide strip of Fibersorb® was placed between two
sheets of 40 mil (1 mm) HOPE sheets to simulate use as a field seaming
material.
The samples were back-pressure saturated and permeated at an effective confining stress of
0.15 kg/cm2 (15 kPa) with a head difference of 50 mm of water. Results are summarized in
Table 7.1.
Table 7.1. Summary of Results of Hydraulic Conductivity Tests on Fibersorb® (from STS
Consultants, 1990).
Sample Test Conditions Hydraulic Conductivity (cm/s)
1 Fibersorb® 3 x 10'8
2 Fibersorb® with Defective HOPE 6 x 10'10
3 Defective HOPE 1 x ID'6
4 Fibersorb® between HOPE Overlap 5 x 10'9
64
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Section 8.0
Equivalency
The main function of low-permeability, compacted soil is either to restrict infiltration
of water into buried waste (in cover systems) or to limit seepage of leachate from the waste (in
liner systems). Other objectives may include enhancement of the efficiency of an overlying
drainage layer, development of composite action with a flexible membrane liner (FML),
adsorption and attenuation of leachate, restriction or gas migration, and others. In the case of a
cover system, compacted soil must also have the ability to withstand subsidence and must be
repairable if damaged by freezing, desiccation, or burrowing animals. For liner systems, the
ability of the liner to withstand chemical degradation from the liquids to be contained. In
addition, low-permeability compacted soil must have adequate shear strength to support itself
on slopes and to support the weight of overlying materials or equipment.
An alternative barrier material, in order to be fully equivalent to a compacted soil
layer, must serve the same functions as compacted soil. Due to inherent differences in the
composition and construction of compacted soil and alternative barriers, the two categories of
materials can never be "equivalent" in all possible respects. For example, compacted soil is
usually from 2 to 5 ft (0.6 to 1.5 m) thick whereas the alternative barriers discussed in this
report are typically no thicker than approximately 1/2 in. (13 mm). Due to differences in
thickness, the alternative barrier material is bound to be more vulnerable to puncture than the
much thicker layer of compacted soil.
Fundamental differences between compacted, low-permeability soil and the alternative
barriers discussed in this report create inevitable differences in hydraulic properties,
attenuation capacity, time of travel of chemicals, strength, desiccation resistance, freeze/thaw
resistance, reaction to settlement, ease of repair, and useful life. Table 8.1 presents a
qualitative list addressing the differences between compacted soil and alternative barrier
materials.
When the potential use of an alternative barrier is evaluated for a particular project,
the critical functions of the barrier should be identified. "Equivalency" should be evaluated on
the basis of the critical parameters and not necessarily upon all potential areas of comparison.
Further, it should be kept in mind that all liner materials have inherent advantages and
disadvantages — no one type of liner (including low-permeability, compacted soil) is a
panacea. Some of the potential advantages of alternative barriers over low-permeability,
compacted soil are as follows:
65
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Table 8.1 Comparison of Differences in Alternative Barrier Materials
Compacted Soil
Thick (2 ft - 5 ft, or 0.6 - 1.5 m)
Field Constructed
Hard to Build Correctly
Impossible to Puncture
Constructed with Heavy Equipment
Often Requires Test Pad at Each Site
Site-Specific Data on Soils Needed
Large Leacnate-Attenuation Capacity
Relatively Long Containment Time
Large Thickness Takes Up Space
Cost Is Highly Variable
Soil Has Low Tensile Strength
Can Desiccate and Crack
Difficult to Repair
Vulnerable to Freeze/Thaw
Damage
Performance Is Highly Dependent
Upon Quality of Construction
Slow Construction
Alternative Barrier Materials
Thin (< 10 mm)
Manufactured
Easy to Build (Unroll & Place)
Possible to Damage and Puncture
Light Construction Equip. Can Be Used
Repeated Field Testing Not Needed
Manufactured Product; Data Available
Small Leachate-Attenuation Capacity
Shorter Containment Time
Little Space Is Taken
More Predictable Cost
Higher Tensile Qtrength
Can't Crack Unin Wetted
(after Construction)
Not Difficult to Repair
Probably Less Vulnerable to
Freeze/Thaw Damage
Hydraulic Properties Are Less
Sensitive to Construction Variabilities
Much Faster Construction
66
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The installation of alternative barriers proceeds rapidly and relatively simply
(construction of low-permeability, compacted soil is slower and requires a
much higher level sophistication in construction technique);
Because of the higher level of sophistication required for proper construction
and protection of low-permeability, compacted soil liners, the alternative
barriers may provide a more predictable end-product for situations in which
the quality of construction of a compacted soil liner cannot be assured;
Alternative barriers, which cost approximately $0.50 to $1.00 per square
foot ($5.50 to $11 per square meter) installed, are often less expensive than
compacted soil and can be installed at a more predictable cost than compacted
soil liners;
Alternative barriers occupy much less volume than compacted soil, which has
three ramifications: (1) more space is available in landfills for waste with the
thin, alternative barrier; (2) fewer truckloads of delivered material are
needed for the alternative barrier compared to compacted soil liners, which can
have important implications for transportation impacts when soil must be
obtained from off-site; and (3) because the alternative barrier weighs less
than the thicker compacted soil, less settlement of underlying waste (for cover
applications) would result with alternative barriers;
Alternative barriers can be installed with light-weight equipment, which is
particularly advantageous for placing liners on top of geosynthetic components,
e.g., a primary liner placed on top of a secondary leachate collection and
removal system;
Once an alternative barrier material is thoroughly characterized and field
tested, there should be no need to retest it unless the materials or installation
procedures change;
Some alternative barrier materials possess unique self-healing characteristics
derived from the expansive nature of bentonite.
The alternative barriers are not without caveats. Some of the potential disadvantages of
alternative barriers include the following:
67
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There is a general lack of data and independent research on the alternative
barrier materials;
Field experience is very limited for most of the alternative barrier materials,
and field performance data is virtually nonexistent;
Because the alternative barriers are thin, they are vulnerable to damage from
puncture, e.g., from traffic or construction equipment such as bulldozers, over
unprotected or improperly protected sections or during placement of cover
materials;
Sodium bentonite is more vulnerable to adverse chemical reactions from
leachate than the clay minerals found in most compacted soil liners;
The effects of settlement of underlying waste upon the hydraulic integrity of the
materials 'has not been evaluated;
The effects of cyclic wetting and drying of the materials upon bulk shrinkage
has not been adequately investigated;
Characterization of performance of overlapped seams under actual field
conditions is incomplete;
The low shear strength of bentonite raises questions about the stability of
alternative barrier materials containing bentonite when such materials are
placed on slopes.
One of the areas of application that was relatively uncontroversial was the use of
alternative barrier materials as a back-up to a flexible membrane liner in the primarily liner
of a double liner system. The EPA does not require a clay liner in the uppermost liner for
doubly-lined, hazardous waste landfills; an alternative barrier used in this situation involves
placing an extra component beyond the minimum requirements.
68
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Section 9.0
Concerns
During a concluding open discussion session of the Workshop, attendees voiced their
concerns regarding the behavior of alternative barriers and discussed informational needs that
would provide a better understanding of the characteristics of these manufactured materials.
The major concerns, expressed in question form, were as follows:
• Concerning stability -- Should alternative barriers be used in landfill caps
having slopes equal to or greater that 10°? And if so, would reinforcing the
cover soil, e.g., with a geogrid, and construction of an anchor eliminate the
instability problem? Do engineers have sufficient experience with and
knowledge of these materials to allow building on slopes with a high level of
confidence?
• Concerning temporary versus permanent use in a cap — Alternative materials
should be seriously considered as a temporary cap for some RCRA or CERCLA
sites for which settlement that would damage a final cover is anticipated. How
would the alternative barrier material react to significant settlement? Although
the alternative barrier would appear to be easy to repair, are there practical
problems in repairing the materials that have not been anticipated?
• Concerning application in dry climates — Compacted soils have limited self-
healing .capability, especially at low stress, and are vulnerable to damage from
desiccation after they are constructed. Alternative barrier materials are less
vulnerable to damage from desiccation after they are installed because they are
installed dry. Should alternative barriers be given stronger consideration for
applications in arid regions? If so, are there other problems with use of
alternative barriers in arid regions, such as bulk shrinkage upon drying, that
might prove to be significant?
• Concerning installation -- What happens when it rains during construction?
What happens to hydraulic conductivity if the material is wetted before
overburden is placed? How much overburden is needed to form an adequate
seam? What if the alternative barrier is placed on a small pebble; will the
bentonite be pushed aside and cause and increase in permeability? A great deal of
69
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[,tmj , , ; iH.,:;;.[..,. , i. :.;.;,..:; , . . ., ,J,i..*....~,lUUl(IIIU
care would appear to be necessary to install the alternative barrier material
correctly -- is it reasonable to assume that the necessary degree of care will be
exercised in the installation of the alternative barrier material?
Concerning application in the field -- The following concerns were expressed.
There is a strong need to see real performance; laboratory data alone are not
enough. Possibly a slow approach to the use of alternative barrier materials
would be wise. The least controversial applications of alternative barrier
materials appear to be landfill covers on reasonably flat surfaces, primary
lining systems for which there is a conventional FML/compacted clay secondary
liner located beneath the primary liner, and liner or cover systems in arid
regions. In these situations, there is less doubt about performance, less risk
involved, and the performance may be easier to assess.
Concerning field performance -- Routine methods to monitor actual performance
of field installations is badly needed. Installation of large (e.g., 2 m) diameter
collection lysimeters underneath these barrier materials is feasible and is
encouraged to provide a credible base of data on field performance.
70
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Section 10.0
Informational Needs
The workshop was concluded by compiling a list of issues for which more information is
needed. The "needs" were established with the goal of generating the data that design engineers,
owner/operators, and regulatory personnel require to have a high level of confidence that
alternative barrier materials will provide the required environmental protection functions in
waste management applications. The following is a condensed version of this list.
1. Shear Strength
a. Interfacial friction with other liner/cover components
b. Long term performance
c. Water diffusion effects; point wetting
d. Standardized testing procedures
e. Laboratory versus field scale
2. Hydraulic Properties
a. Hydraulic conductivity
b. Attenuation capacity
c. Hydration with water versus leachate
d. Composite action; does a composite seal form?
e. Migration of bentonite
f. Laboratory versus field scale
3. Environmental Effects
a. Freeze/thaw resistance
b. Desiccation resistance
c. Effects of settlement
d. Self healing capabilities
e. Effects of rock beneath alternative barrier
f. Laboratory versus field scale
4. Seams
a. Hydraulic properties
b. Strength
c. Effects of settlement
71
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d. Wrinkled seam (wrinkle of liner above or below and of alternative barrier
itself)
e. Laboratory versus field scale
5. Quality Assurance/Quality Control
a. Manufacture
b. Transportation
c. Installation
6. Applications
a. Caps versus liners
b. Humid versus arid regions
c. Compressible and incompressible waste
7. Thermal Effects
a. Differential expansion of alternative barrier with other liner materials,
especially with HDPE/bentonite composite, that could cause wrinkles or
delamination of materials
b. Shrinkage of materials upon drying, causing a reduction in overlap width
8. Mechanical Properties
9. Comparison with Compacted Soil
10. Useful Life; Aging.
The list was prioritized in the following order:
1. Shear strength
2. Hydraulic properties
3. Seams
4. Useful life.
More information about these research needs, plus other issues not listed above, is
expected to become available over the next few months and years. Individuals with information
are encouraged to pass that information along to David E. Daniel, University of Texas,
Department of Civil Engineering, Austin, TX 78712, or to Walter E. Grube, Jr., U. S.
Environmental Protection Agency, Risk Reduction Engineering Laboratory, Cincinnati, OH
45268. Of particular interest are unpublished data, for example, developed for a particular
project such as a DOE cover project, that might otherwise not be widely disseminated.
72
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Many individuals attending the Workshop expressed a desire to hold a similar Workshop
in 1 to 2 years to present and to discuss new information. If a significant base of new data is
developed, the new information would likely be the focal point of discussions in the next
Workshop.
73
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Section 11.0
List of References
Benson, C. B., and Daniel, D. E. (1990), "Influence of Clods on Hydraulic Conductivity of
Compacted Clay," Journal of Geotechnical Engineering. Vol 116, No. 8, pp. 1231-1248.
Broderick, G. P., and Daniel, D. E. (1990), "Stabilizing Compacted Clay Against Chemical
Attack," Journal of Geotechnical Engineering. Vol. 116, No. 10, pp. 1549-1567.
Brown, K. W.f Thomas, J. C., and Green, J. W. (1984), "Permeability of Compacted Soils to
Solvents Mixtures and Petroleum Products," Proceedings. Tenth Annual Research
Symposium on Land Disposal of Hazardous Waste, U. S. EPA, Cincinnati, Ohio, EPA-600/9-
84-007, pp. 124-137.
Chen-Northern , Inc. (1988), Untitled Letter Report with Results of Laboratory Tests on
Claymax®, Denver, Colorado, December 31.
Daniel, D. E. (1987), "Earthen Liners for Land Disposal Facilities," in Geotechnical Practice
for Waste Disposal '87. R. D. Woods (ed.), American Society of Civil Engineers, New York,
pp. 21-39.
Daniel, D. E. (1989), "In Situ Hydraulic Conductivity Tests for Compacted Clay," Journal of
Geotechnical Engineering. Vol. 115, No. 9, pp. 1205-1226.
Daniel, D. E. (1990), "Summary Review of Construction Quality Control for Compacted Soil
Liners," Proceedings. Symposium on Regulation, Performance, Construction, Operation of
Waste Containment Systems, San Francisco, November 6-7, American Society of Civil
Engineers, New York (in press).
Geoservices, Inc. (1988a), "Interim Test Results - Claymax Liner, Freeze-Thaw Hydraulic
Conductivity Tests," Report to James Clem Corporation, November 11, 3 p.
74
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Geoservices, Inc. (1988b), "Results of Saline Solution Hydraulic Conductivity Test, Claymax
CR Liner," Report to James Clem Corporation, Norcross Georgia, November 29, 2 p.
Geoservices, Inc. (1989a), "Report on Direct Shear Testing of Selected Claymax CL Interfaces,"
Report to James Clem Corporation, Norcross, Georgia, March 10, 6 p.
Geoservices, Inc. (1989b) "Hydraulic Conductivity of Claymax CR in a Marine Environment,"
Report to James Clem Corporation, Technical Note No. 2, Norcross, Georgia, March, 10 p.
Geoservices, Inc. (1989c), "Freeze-Thaw Effects on Claymax Liner Systems," Report to James
Clem Corporation, Technical Note No. 3, Norcross, Georgia, March, 9 p.
Geoservices, Inc. (1989d), "Final Report, Claymax/Fuel Compatibility Tests," Report to James
Clem Corporation, Norcross, Georgia, July 7, 14 p.
Geoservices, Inc. (1989e), "Report of Moisture Retention Tests, Claymax CR," Report to James
Clem Corp., Norcross, Georgia, July 14, 14 p.
Goldman, L. G., et al. (1988), "Design, Construction, and Evaluation of Clay Liners for Waste
Management Facilities," U. S. EPA, Washington, DC, EPA/530/SW-86-007F.
Gordon, M. E., Huebner, P. M., and T. J. Miazga (1989), "Hydraulic Conductivity of Three
Landfill Clay Liners," Journal of Geotechnical Engineering. Vol. 115, No. 8, pp. 1148-
1162.
Herrmann, J. G., and Elsbury, B. R. (1987), "Influential Factors in Soil Liner Construction for
Waste Disposal Facilities," in Geotechnical Practice for Waste Disposal '87. R. D. Woods
(ed.), American Society of Civil Engineers, New York, pp. 522-536.
J & L Testing Company, Inc. (1990a), "Physical Properties Test Results, Bentonite NW/SS/W
Composite," Report to American Colloid Company, Canonsburg, Pennsylvania, May 30, 17p.
J & L Testing Company, Inc. (1990b), "Hydraulic Conductivity Tests, Bentomat NW/Cs/W,
Bentomat NW/SS/W," Report to American Colloid Company, Canonsburg, Pennsylania, July
5.
75
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Lutz, D.P. (1990), Barrier Equivalency of Liner and Cap Materials, M. S. Thesis, The
University of Texas, Austin, Texas, 90 p.
Mitchell, J. K., Hooper, D. R., and Campanella, R. G. (1965), "Permeability of Compacted
Clay," Journal of the Soil Mechanics and Foundations Division. ASCE, Vol. 91, No. SM4, pp.
41-65.
Pittsburgh Testing Laboratory (1985), "Permeability Test of Paraseal Water Proofing
Membrane," Report to Paramount Technical Products, Inc., Salt Lake City, November 27, 2
P-
STS Consultants Ltd. (1984), "Permeability Testing on Enviromat Material Seam
Applications," Letter Report to Ciem Environmental Corporation, Northbrook, Illinois, July
16, 3p.
STS Consultants Ltd. (1988a), "Hydraulic Conductivity Testing of Claymax Liner Material after
Subjecting the Specimen to 15% Elongation," Letter Report to Clem Environmental
Corporation, Northbrook, Illinois, April 25, 4 p.
STS Consultants Ltd. (1988b), "Hydraulic Conductivity Determination of Claymax Utilizing
Sewage Leachate as a Permeant and Hydration Medium," Report to Clem Environmental
Corporation, Northbrook, Illinois, 4 p.
STS Consultants Ltd. (1988c), "Hydraulic Conductivity Determination of Claymax Material
Utilizing Paper Sludge at the Permeant," Report to Clem Environmental Corporation,
Northbrook, Illinois, July 7, 4 p.
STS Consultants Ltd. (1989a), "Hydraulic Conductivity and Compatibility Testing of Claymax,
Baltimore County Landfill Project, Townson, Maryland," Report to Clem Environmental
Corporation, May 11, 6 p.
STS Consultants Ltd. (1989b), "Hydraulic Conductivity Testing, RCRA Shelton Ash Mono Cell
Landfill," Report to Clem Environmental Corporation, May 11, 6 p.
76
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STS Consultant Ltd. (1990), "Hydraulic Conductivity Testing of Arco Fibersorb SA-7000,"
Report to ARCE Chemical Company, Northbrook, Illinois, April 18, 3p.
Scheu, C., Johannben, and Saathoff, F. (1990), "Non-Woven Bentonite Fabrics - A New Fiber
Reinforced Mineral Liner System," Geotextiles. Geomembranes and Related Products. Den
Hoet (ed), Balkema, Rollerdam, pp. 467-472..
Schubert, W.R. (1987), "Bentonite Matting in Composite Lining Systems," in Geotechnical
Practice for Waste Disposal '87. R. D. Woods (ed.), American Society of Civil Engineers
Conference , New York, pp. 784-796..
Shan, H.Y. (1990), "Laboratory Tests on Bentonitic Blanket/ M. S. Thesis, University of
Texas, Austin, Texas, 84 p.
Twin City Testing Corporation (1986), "Laboratory Permeability Testing of Membrane with
Bentonite Backing Seal," Report to Paramount Technical Products, St. Paul, Minnesota, May
30, 6 p.
U. S. Environmental Protection Agency (1985), "Draft Minimum Technology Guidance on
Double Liner Systems for Landfills and Surface Impoundments ~ Design, Construction, and
Operation," Office of Solid Waste and Emergency Response, Washington, DC, EPA/530-SW-
014, 70 p.
U. S. Environmental Protection Agency (1986), "Technical Guidance Document: Construction
Quality Assurance for Hazardous Waste Land Disposal Facilities," Office of Solid Waste and
Emergency Response, Washington, DC, EPA/530-SW-86-031, 88 p.
U. S. Environmental Protection Agency (1989), "Technical Guidance Document: Final Covers on
Hazardous Waste Landfills and Surface Impoundments," Office of Solid Waste and Emergency
Response, Washington, DC, EPA/530-SW-89-047.39 p.
Zimmie, T.F. and Plante, C.L (1990), "The Effect of Freeze/Thaw Cycles on the Permeability of
a Fine Grained Soil," Proceedings. Mid-Atlantic Industrial Waste Conference, Philadelphia,
July (in press).
77
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APPENDIX
LIST OF PARTICIPANTS
78
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Registrants -- EPA Workshop
June 6-7, 1990 Cincinnati, Ohio
Rodney Aldrich
NY State DEC
50 Wolf Rd.
Albany, NY 12233
Richard Andersen
Texas Water Commission
P.O. Box 13087
Austin, TX 78711
Mary F. Beck
U.S. EPA Region III
841 Chestnut St.
Pnilsdelphia, PA 19107
Craig H. Benson
Dept. of Civil & Env. Engr.
2214 Engineering Bldg.
University of Wisconsin
Madison, Wl 53706
Jane Bolton
Army Corps of Engineers
CEMRO-ED-GF
215 No. 17th St.
Omaha, NE 68134
John Boschuk, Jr.
J&L Testing Co.
938 S. Central Ave.
Canonsburg, PA 15317
John Bove
Westinghouse Corp.
11785 Highway Dr. #100
Cincinnati, OH 45241
John Bowders
Dept. of Civil Engineering
653D Engr. Sciences Bldg.
West Virginia University
Morgantown, WV 26506-
6101
Karen Brady
Tennessee Valley Authority
NFE-1AF 112-G
Muscle Shoals, AL 35660
Ed Brdicka
Ohio EPA
1800 Watermark Dr.
P.O. Box 1049
Columbus, OH 43266-1049
Mark Cadwallader
Gundle Lining Co.
19103 Gundle Rd.
Houston, TX 77073
David Carson
U.S. EPA
26 West ML King Dr.
Cincinnati, OH 45268
Eric Chiado
Almes & Associates
RD #1, Box 520
Pleasant Valley Rd.
Trafford, PA 15085
Yoon-Jean Choi
U.S. EPA, Region 1
Waste Mgmt. Division
JFK Federal Bldg.
Boston, MA 02203
Glenn N. Coffman
Law Environmental Inc.
112 Town Park Dr.
Kennesaw, GA 30144
Jack Conner
Meredith Brothers
6013 Tulip Hill Rd.
Columbus, OH 43235
Larry C. Cox
Automated Sciences Group
800 Oak Ridge Turnpike
#C102
Oak Ridge, TN 37830
David E. Daniel
Dept. of Civil Engineering
ECJ 9.102E
The University of Texas
Austin, TX 78712
Dennis L Datin
OK State Dept. of Health
1000 N.E. Tenth St.
Oklahoma City, OK 73152
Annette DeHavilland
Ohio EPA
P.O. Box 2198
Columbus, OH 43266-0149
Gary S. Deutshman
Ohio EPA
1035 Deulac Grove Dr.
Bowling Green, OH 43402
Michael Dewsbury
ARCO Chemical Co.
3801 West Chester Pike
Newtown Square, PA 19073
Ed Doyle
Waste Mgmt. of N. America
3003 Butterfield Rd.
Oak Brook, IL 60521
R. Jeffrey Dunn
Kleinfelder, Inc.
2121 N. California Blvd.
#570
Walnut Creek, CA 94596
Ron Ebelhar
Westinghouse Environmental
and Geotechnical Services
11785 Highway Dr. #100
Cincinnati, OH 45241
David Eberly
U.S. EPA-OSW (OS-343)
401 M St., S.W.
Washington, D.C. 20460
Marcia Ellis
NY State DEC
50 Wolf Rd. #230
Albany, NY 12233
79
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EPA Registrants - Continued
Page 2
Allan Erickson
CH2M Hill
310 W. Wisconsin Ave. #700
Milwaukee, Wl 53201
Paula Estornell
Dept. of Civil Engineering
ECJ 9.102E
The University of Texas
Austin, TX 78712
Douglas N. Excell
American Colloid
1500 W. Shure Dr.
Arlington Heights, IL 60004
Heidi Facklam
U.S. Army Corps of Engineers
Missouri River Division
P.O. Box103DTS
Omaha, NE 68101-0103
A. A. Freitag
Bechtel Savannah River Inc.
802 E. Martintown Rd.
N. Augusta, SC 29841
John Gardner
Almes & Associates, Inc.
RD #1, Box 520
Pleasant Valley Rd.
Trafford, PA 15085
Sal Gazioglu
Dames & Moore
4141 Blue Lake, Suite 190
Dallas, TX 75244
George F. Gilbert
Division of Waste Management
18 Reilly Rd.
Frankfort, KY 40601
George Gtos
Bechtel Savannah River
Project
802 E. Martintown Rd.
BTC416
N. Augusta, SC 29841
G. Hossein Golshir
Westinghouse Corp.
802 E. Martintown Rd.
North Augusta, SC 29841
Walter E. Grube, Jr.
U.S. EPA Hazardous Waste
Engineering Laboratory
26 West ML King Dr.
Cincinnati, OH 45268
J. Scott Heisey
American Electric Power SC
1 Riverside Plaza
Cincinnati, OH 43215
Ron Hill
U.S. EPA
26 West ML King Dr.
Cincinnati, OH 45268
Michael Kostanian
Bechtel Environmental
50 Beale St.
San Francisco, CA 94119-
3965
Andrew Leung
TAMS Consultants Inc.
300 Broodacres Dr.
Bloomfield, NJ 07003
James D. Liner
Milwhite, Inc.
P.O. Box 15038
Houston, TX 77220-5038
J.T. Massey-Norton
American Electric Power SC
1 Riverside Plaza
Columbus, OH 43215
John D. Holm Tony Maxson
Army Corps of Engineers Chemical Waste Mgmt.
601 E. 12th St. 3001 Butterfield Rd.
Kansas City, MO 64106-2896 Oak Brook, IL 60521
Janet M. Houthoofd
U.S. EPA
26 West ML King Dr.
Cincinnati, OH 45268
Jon Hutchings
Minnesota Pollution Control
520 Lafayette Rd.
St. Paul, MN 55155
Jim Klang
Minnesota Pollution Control
520 Lafayette Rd.
St. Paul, MN 55155
Robert M. Koerner
Drexel University
Geosynthetic Research
Institute
West Wing- Rush Bldg.
Philadelphia, PA 19104
John M. McBee
R.F. Weston, Inc.
5301 Central Ave., N.E. #100
Albuquerque, NM 87108
Patrick McGroarty
Paramount Technical Products
2600 Paramount Dr.
Spearfish, SD 57783
John E. Moylan
Army Corps of Engineers
601 E. 12th St.
Kansas City, MO 64106-2896
Durge S. Nagda
Division of Waste Management
18 Reilly Rd.
Frankfort, KY 40601
80
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EPA Registrants - Continued
Page 3
Jeff W. Newell
Charles T. Main, Inc.
4701 Hedgemore Dr.
Charlotte, NC 28209
Gary Oberholtzer
Bechtel Corp.
P.O. Box 3965
San Francisco, CA 94119
Jim Olsta
American Colloid
1500 W. Shure Dr.
Arlington Heights, IL 60004
Mary Osika
Ohio EPA
P.O. Box 1049
1800 Watermark Dr.
Columbus, OH 43266-0149
Donald Perander
ARMCO, Inc.
P.O. Box 600
Middletown, OH 45043
Mark Phifer
Westinghouse Corp.
802 E. Martintown Rd.
North Augusta, SC 29841
Bob Randolph
Soil Stablization Products
P.O. Box 2779
Merced, CA 95344
Gregory Richardson
Westinghouse Corp.
P.O. Box 58069
Raleigh, NC 27658
Charles Rivette
Browning-Ferris Industries
757 N. Eldridge Rd.
Houston, TX 77079
Nancy Roberts
ERCE
P.O. Box 22879
Knoxville, TN 37993
Mary Rogers
Chambers Development Co.
10700 Frandstown Rd.
Pittsburgh, PA 15235
L.H. Schroeder
Bechtel Savannah River Inc.
802 E. Martintown Rd.
N. Augusta, SC 29841
Dana Sheets
American Electric Power
1 Riverside Plaza
Columbus, OH 43216
Martin Simpson
James Clem Corp.
444 N. Michigan, #1610
Chicago, IL 60611
William Simpson
James Clem Corp.
444 N. Michigan, #1610
Chicago, IL 60611
Kenneth Skahn
U.S. EPA (OS-220)
401 M St., S.W.
Washington, D.C. 20460
Thomas Stam
American Colloid
1500 W. Shure Dr.
Arlington Heights, IL 60004
Lindsay Taliaferro III
Ohio EPA
1800 Watermark Dr.
P.O. Box 1049
Columbus, OH 43266-0149
Steve Walker
Polyfelt, Inc.
1000 Abernathy Rd.
Atlanta, GA 30338
Bryan Wilson
American Electric Power SC
1 Riverside Plaza
Cincinnati, OH 43215
Thomas Zimmie
Rensselaer Polytechnic Inst.
Dept. of Civil Engineering
Troy, NY 12180
81
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