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).

-------
              -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).

-------
       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

-------
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

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"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

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                                      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

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           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

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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

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                 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

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("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

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      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

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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

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                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.

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             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

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         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

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                                      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

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               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

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       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

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      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

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                                                               •... . 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

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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

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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
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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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