vvEPA
United States
Environmental Protection
Agency
Office of Emergency and
Remedial Response
Washington, DC 20460
Superfund
EPA/540/S-92/008
Engineering Bulletin
Slurry Walls
Office of
Research and Development
Cincinnati, OH 45268
October 1992
Purpose
Section 121 (b) of the Comprehensive Environmental Re-
sponse, Compensation, and Liability Act (CERCLA) mandates
the Environmental Protection Agency (EPA) to select remedies
that "utilize permanent solutions and alternative treatment
technologies or resource recovery technologies to the maxi-
mum extent practicable" and to prefer remedial actions in
which treatment "permanently and significantly reduces the
volume, toxicity, or mobility of hazardous substances, pollut-
ants, and contaminants as a principal element." The Engineer-
ing Bulletins are a series of documents that summarize the latest
information available on selected treatment and site remediation
technologies and related issues. They provide summaries of
and references for the latest information to help remedial project
managers, on-scene coordinators, contractors, and other site
cleanup managers understand the type of data and site
characteristics needed to evaluate a technology for potential
applicability to their Superfund or other hazardous waste site.
Those documents that describe individual treatment technolo-
gies focus on remedial investigation scoping needs. Addenda
will be issued periodically to update the original bulletins.
Abstract
Slurry walls are used at Superfund sites to contain the
waste or contamination and to reduce the potential of future
migration of waste constituents. In many cases slurry walls are
used in conjunction with other waste treatment technologies,
such as covers and ground water pump-and-treat systems.
The use of this well-established technology is a site-specific
determination. Geophysical investigations and other engineer-
ing studies need to be performed to identify the appropriate
measure or combination of measures (e.g., landfill cover and
slurry wall) to be implemented and the necessary materials of
construction based on the site conditions and constituents of
concern at the site. Site-specific compatibility studies may be
necessary to document the applicability and performance of
the slurry wall technology. The EPA contact whose name is
listed at the end of this bulletin can assist in the location of
other contacts and sources of information necessary for such
studies.
This bulletin discusses various aspects of slurry walls includ-
ing their applicability, limitations on their use, a description of
the technology including innovative techniques, and materials
of construction including new alternative barrier materials, site
requirements, performance data, the status of these methods,
and sources of further information.
Technology Applicability
Slurry walls are applicable at Superfund sites where re-
sidual contamination or wastes must be isolated at the source
in order to reduce possible harm to the public and environment
by minimizing the migration of waste constituents present.
These subusurface barriers are designed to serve a number of
functions, including isolating wastes from the environment
thereby containing the leachate and contaminated ground
water, and possibly returning the site to future land use.
Slurry walls are often used where a waste mass is too large
for practical treatment, where residuals from the treatment are
landfilled, and where soluble and mobile constituents pose an
imminent threat to a source of drinking water. Slurry walls can
generally be implemented quickly, and the construction re-
quirements and practices associated with their installation are
well understood.
The design of slurry walls is site specific and depends on
the intended function(s) of the system. A variety of natural,
synthetic, and composite materials and construction techniques
are available for consideration when they are selected for use at
a Superfund site.
Slurry walls can be used in a number of ways to contain
wastes or contamination in the subsurface environment, thereby
minimizing the potential for further contamination. Typical
slurry wall construction involves soil-bentonite (SB) or cement-
bentonite (CB) mixtures. These structures are often used in
conjunction with covers and treatment technologies such as in
situ treatment and ground water collection and treatment
systems. Source containment can be achieved through a num-
ber of mechanisms including diverting ground water flow,
capturing contaminated ground water, or creating an upward
ground water gradient within the area of confinement (e.g., in
conjunction with a ground water pump-and-treat system).
Containment may also be achieved by lowering the groundwa-
ter level inside the containment area. This will help to reduce
hydraulically driven transport (known as "advective transport")
from the containment area. However, even if the hydraulic
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gradient is directed towards the containment area, transport of
the contaminants (although thought to be minimal) is still
possible. In many cases slurry walls are expected to be in
contact with contaminants, therefore, chemical compatibility
of the barrier materials and the contaminants may be an issue
[1, p. 373-374].
The effectiveness of slurry walls and high density polyethyl-
ene (HOPE) geomembranes on soils and ground water con-
taminated with general contaminant groups is shown in Table
1. Examples of constituents within contaminant groups are
provided in the "Technology Screening Guide for Treatment of
CERCLA Soils and Sludges" [2]. This table is based on current
available information or on professional judgment where no
information was available. The proven effectiveness of the
technology for a particular site or waste does not ensure that it
will be effective at all sites or that the containment efficiencies
achieved will be acceptable at other sites. For ratings used in
this table, demonstrated effectiveness means that, at some
scale, compatibility tests showed that the technology was effec-
tive or compatible with that particular contaminant and matrix.
Table 1
Effectiveness of HOPE Geomembranes and Slurry Walls
on General Contaminant Groups for Soil and
Groundwater
Contaminant Croups
Effectiveness
HOPE Slurry Wall:
Geomembranes SB CB
Halogenated volatiles
Halogenated semivolatiles
Nonhalogenated volatiles
Nonhalogenated semivolatiles
PCBs
Pesticides (halogenated)
Dioxins/Furans
Organic cyanides
Organic corrosives
V V
T T
T T
T T
T T
T V
T T
T T
o n
Volatile metals
Nonvolatile metals
Asbestos
Radioactive materials
Inorganic corrosives
Inorganic cyanides
T
T
Oxidizers
Reducers
o
V
a
O
• Demonstrated Effectiveness: Short-term effectiveness demonstrated
at some scale.
V Potential Effectiveness: Expert opinion that technology will work.
Q No Expected Effectiveness: Expert opinion that technology will
not work.
The ratings of potential effectiveness and no expected effective-
ness are both based on expert judgment. Where potential
effectiveness is indicated, the technology is believed capable of
successfully containing the contaminant groups in a particular
matrix. When the technology is not applicable or will probably
not work for a particular combination of contaminant group
and matrix, a no-expected-effectiveness rating is given.
Limitations
In the construction of most slurry walls it is important that
the barrier is extended and properly sealed into a confining
layer (aquitard) so that seepage under the wall does not occur.
For a light, non-aqueous phase liquid a hanging slurry may be
used. Similarly, irregularities in the wall itself (e.g., soil slumps)
may also cause increased hydraulic conductivity.
Slurry walls also are susceptible to chemical attack if the
proper backfill mixture is not used. Compatibility of slurry wall
materials and contaminants should be assessed in the project
design phase.
Slurry walls also may be affected greatly by wet/dry cycles
which may occur. The cycles could cause excessive desiccation
which can significantly increase the porosity of the wall.
Once the slurry walls are completed, it is often difficult to
assess their actual performance. Therefore, long-term ground
water monitoring programs are needed at these sites to ensure
that migration of waste constituents does not occur.
Technology Description
Low-permeability slurry walls serve several purposes includ-
ing redirecting ground water flow, containing contaminated
materials and contaminated ground water, and providing in-
creased subsurface structural integrity. The use of vertical barri-
ers in the construction business for dewatering excavations and
building foundations is well established.
The construction of slurry walls involves the excavation of a
vertical trench using a bentonite-water slurry to hydraulically
shore up the trench during construction and seal the pores in
the trench walls via formation of a "filter cake" [3, p. 2-17].
Slurry walls are generally 20 to 80 feet deep with widths 2 to 3
feet. These dimensions may vary from site to site. There are
specially designed "long stick" backhoes that dig to 90 foot
depths. Generally, there will be a substantial cost increase for
walls deeper than 90 feet. Clam shell excavators can reach
depths of more than 150 feet. Slurry walls constructed at water
dam projects have extended to 400 feet using specialized mill-
ing cutters. Depending on the site conditions and contami-
nants, the trench can be either excavated to a level below the
water table to capture chemical "floaters" (this is termed a
"hanging wall") or extended ("keyed") into a lower confining
layer (aquitard) [3, p. 3-1]. Similarly, on the horizontal plane
the slurry wall can be constructed around the entire perimeter
of the waste material/site or portions thereof (e.g., upgradient,
* [reference number, page number]
Engineering Bulletin: Slurry Walls
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Figure 1
Aerial and Cross-section View Showing Implementation of Slurry Walls (4)
Groundwater Flow
Slurry Wall
• Groundwater Monitoring Well
O Groundwater Extraction Well
LANDFILL COVER
WASTE MATERIAL
SLURRY WALL
BEDROCK OR AQUITARD
downgradient). Figure 1 diagrams a waste area encircled by a
slurry wall with extraction and monitoring wells inside and
outside of the waste area, respectively along with a cross-
section view of a slurry wall being used with the landfill cover
technology [4, p. 1].
The principal distinctions among slurry walls are differ-
ences in the low-permeability materials used to fill the trenches.
The ultimate permeability of the wall is controlled by water
content and ratios of bentonite/soil or bentonite/cement. In
the case of a SB wall, the excavated soil is mixed with bentonite
outside of the trench and used to backfill the trench. During the
construction of a CB slurry wall, the CB mixture serves as both
the initial slurry and the trench backfill. When this backfill gels
(SB) or sets (CB), the result is a continuous barrier with lower
permeability than the surrounding soils. A landfill cover, if
Engineering Bulletin: Slurry Walls
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Figure 2
Schematic Diagram of Typical Slurry Wall and Bio-polymer Slurry Trench
(9)'
* Drawing not to scale
Y
///
•j
^
V
SLURRY
* WALL
•*—*// v\ /// ^
BEDROCK OR
AQUITARD
KEY
employed, must extend over the finished slurry wall to com-
plete the containment and to avoid desiccation.
Soil-bentonite slurry walls are the most popular since they
have a lower permeability than CB walls, and are less costly [3,
p. 1-6] [5, p. 2]. Attapulgite may also be used in situations
where the bentonite is not compatible with the waste [5, p.16].
A newer development is the use of fly ash as a high carbon
additive not only to lower the permeability of the SB but also to
increase the adsorption capacity of the SB with respect to the
transport of organic chemicals [6, p. 1][7, p. 444]. Permeabilities
of SB walls as low as 5.0 x 10'9 cm/sec have been reported
although permeabilities around 1 x 10'7 cm/sec are more typi-
cal [3, p. 2-28]. The primary advantage of the CB wall is its
greater shear strength and lower compressibility. CB walls are
often used on unstable slopes and steep terrain or where soils of
low permeability are not accessible [3, p. 2-40]. The lowest
permeabilities of CB walls are typically 1 x 1Q-6 cm/sec or
greater [3, p. 2-42] [5, p. 14]. It should be noted that organic
and inorganic contaminants in ground water/leachate can have
a detrimental effect on bentonite and the trench backfill mate-
rial in both SB and CB walls. Therefore, it is imperative that a
compatibility testing program be conducted in order to deter-
mine the appropriate backfill mixture.
Composite slurry walls incorporate an additional barrier,
such as a geomembrane, within the trench to improve imper-
meability and chemical resistance. The geomembranes often
are plastic screens that are comprised of HOPE pile plank sec-
tions which lock together. The locking mechanism is designed
to minimize the leakage of the contaminated ground water.
Table 2 shows one vendor's experience in using HOPE as a
geomembrane [8]. The membrane: is easy to install; has a long
life; and is resistant to animal and vegetation intrusion, microor-
ganisms, and decay. Combining the membrane with a bento-
nite slurry wall may be the most effective combination. It is
usually effective to construct the bentonite-cement slurry wall
and then install the membrane in the middle of the wall. The
toe of the membrane sheet is stabilized in the backfill material,
cement, or in a special grout [5, p.4]. The installation is
reported to be effective in most every type of soil, is watertight
and may be constructed to greater depths.
A relatively new development in the construction of slurry
walls is the use of mixed-in-place walls (also referred to as soil-
mixed walls). The process was originally developed in japan. A
drill rig with multi-shaft augers and mixing paddles is used to
drill into the soil. During the drilling operation a fluid slurry or
grout is injected and mixed with the soil to form a column. In
constructing a mixed-in-place wall the columns are overlapped
to form a continuous barrier. This method of vertical barrier
construction is recommended for sites where contaminated
soils will be encountered, soils are soft, traditional trenches
might fail due to hydraulic forces, or space availability for
construction equipment is limited. Both this method and a
modified method termed "dry jet mixing" are usually more
expensive than traditional slurry walls [5, p. 7] [9].
Another application of traditional slurry wall construction
techniques is the construction of permeable trenches called
bio-polymer slurry drainage trenches [10] [11]. Figure 2 dia-
grams a slurry wall and a bio-polymer slurry drainage trench
constructed around a waste source; this will typically involve
the use of a landfill cover in conjunction with the wall. Rather
than restricting ground water flow, these trenches are con-
structed as interceptor drains or extraction trenches for collect-
ing or removing leachate, ground water, and ground water-
borne contaminants. These trenches also can be used as
recharge systems. The construction sequence is the same as
the traditional method described above. However, a biode-
gradable material (i.e., bio-polymer) with a high gel strength is
used in the place of bentonite in the slurry, and the trench is
backfilled with permeable materials such as sand or gravel.
Once the trench is completed, the bio-polymer either degrades
Engineering Bulletin: Slurry Walls
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or is broken with a breaker solution that is applied to the
trench. Once the bio-polymer filter cake is broken the sur-
rounding soil formation returns to its original hydraulic con-
ductivity. Groundwater collected in the trench can be re-
moved by use of an extraction well or other collection system
installed in the trench [10]. A bio-polymer trench can be used
in conjunction with an SB or CB slurry wall to collect leachate or
a contaminated plume within the wall (similar to the function
of a well-point collection system). A geomembrane also can be
installed with the bio-polymer wall to restrict ground water
flow beyond the bio-polymer wall.
Grouting, including jet grouting, employs high pressure
injection of a low-permeability substance into fractured or
unconsolidated geologic material. This technology can be
used to seal fractures in otherwise impermeable layers or con-
struct vertical barriers in soil through the injection of grout into
holes drilled at closely spaced intervals (i.e., grout curtain) [5,
p.8] [12, p. 5-97]. A number of substances can be used as
grout including cement, alkali silicates, and organic polymers
[12, p. 5-97 - 5-101 ]. However, concerns surround the use of
grouting for the construction of vertical barriers in soils because
it is difficult to achieve and verify complete permeation of the
soil by the grout. Therefore, the desired low permeabilities
may not be achieved as expected [5, p.8] [1 3, p. 7].
Site Requirements
Treatment of contaminated soils or other waste materials
requires that a site safety plan be developed to provide for
personnel protection and special handling measures.
The construction of slurry walls requires a variety of con-
struction equipment for excavation, earth moving, mixing, and
pumping. Knowledge of the site, local soil, and hydrogeologic
conditions is necessary. The identification of underground
utilities is especially important during the construction phase [8].
In slurry wall construction, large backhoes, clamshell exca-
vators, or multi-shaft drill rigs are used to excavate the trenches.
Dozers or graders are used for mixing and placement of back-
fill. Preparation of the slurry requires batch mixers, hydration
ponds, pumps, and hoses. An adequate supply of water and
storage tanks is needed as well as electricity for the operation of
mixers, pumps, and lighting. Areas adjacent to the trench
need to be available for the storage of trench spoils (which
could potentially be contaminated) and the mixing of backfill.
If excavated soils will not be acceptable for use in the slurry wall
backfill suitable backfill material must be imported from off the
site. In the case of CB walls, plans must be made for the
disposal of the spoils since they are not backfilled. In marked
contrast, deep soil mixing techniques require less surface storage
area, use less heavy equipment, and may produce a smaller volume
of trench spoils.
Performance Data
Performance data presented in this bulletin should not be
considered directly applicable to all sites. A number of variables
such as geographic region, topography, and material availabil-
ity can affect the walls performance. A thorough characteriza-
tion of the site and a compatability study is highly recom-
mended.
At the Hill Air Force Base in northern Utah the installation
of a slurry wall, landfill covers, groundwater extraction and
treatment, and monitoring was implemented to respond to
ground water and soil contamination at the site. The slurry
wall was installed along the upgradient boundary on three
sides of Operable Unit No. 1 to intercept and divert ground
water away from the disposal site. Operable Unit No. 1 consists
of Landfill No. 3, Landfill No. 4, Chem Pits No. 1 and 2, and Fire
Training Area No. 1. Shallow perched groundwater and soils
present were contaminated with halogenated organics and
heavy metals. The performance of the slurry wall had been
questioned because it was not successfully keyed into the
underlying clay layer. This oversight was attributed to both the
inadequate number and depth of soil borings. The combina-
tion of landfill caps, slurry wall, and ground water extraction
and treatment has resulted in a significant reduction in the
concentrations of organics and inorganics detected seeping at
the toe of Landfill No. 4. Organics were reduced to levels below
5 percent of their pre-remedial action levels and iron was
reduced to 20 percent of its original observed concentration.
Three seperate QA/QC projects were implemented to assess the in
situ effectiveness of the slurry wall. The determination of ground
water levels in monitoring wells on the inside and outside of the
wall provided the most the useful data [14].
Table 2
Relative Chemical Resistivity of an HOPE
Geomembrane (8)a
Aromatic Compounds
Benzene +
Ethylene Benzene ++
Toluene +
Xylene ++
Phenol ++
Polycydk Hydrocarbons
Naphthalene ++
Anthracene ++
Phenanthrene ++
Pyrene ++
Benzopyrene ++
Inorganic Contamination
Fluorine
CN
Sulphides
PO.
++
++
++
++
Chlorinated Hydrocarbons
Chlorobenzenes +
Chlorophenols ++
PCBs ++
Other Sources of Contamination
Tetrahydrofurane +
Pyrides ++
Tetrahydrothiophene ++
Cyclohexanone ++
Styrene ++
Petrol ++
Mineral Oil ++
Pesticides
Organic Chlorine
Compounds ++
Pesticides ++
Key: ++ Good Resistance
+ Average Resistance
Adapted from vendor's marketing brochure
Engineering Bulletin: Slurry Walls
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At the Lipari Landfill Superfund Site in New Jersey, a SB
slurry wall was installed to encircle the landfill. A landfill cover
incorporating a 40 mil HOPE geomembrane, also was installed
at the site. Heavy rains and snowmelt prior to the complete cap
installation resulted in the need to perform an emergency
removal (i.e., dewatering). Several years after completion of
the slurry wall and landfill cover their effectiveness was evalu-
ated during a subsequent feasibility study. The study con-
cluded that the goal of an effective permeability of 1 x 1 (>7 cm/
sec had been achieved in the slurry wall. Monitoring wells will
be located at least 5 feet from the slurry wall on the upgradient
side and 7 feet on the down gradient side [15]. The combina-
tion of technologies being used along with the slurry wall
appears to be effectively containing the waste and its constitu-
ents.
A SB slurry wall, up to 70 feet deep, was installed at a
municipal landfill Superfund site in Cratiot County, Michigan
The slurry wall was needed to prevent leachate from migrating
into the local ground water. Approximately 250,000 ft.2 of SB
slurry wall was installed at the site. The confirmation of achiev-
ing a goal of a laboratory permeability of less than 1 x 10'7 cm/
sec for the soil-bentonite backfill was reported by an indepen-
dent laboratory [16].
A SB slurry wall, extending through three aquifers, was
installed at the Raytheon NPL site in Mountain View, California.
Soil and ground water at the site were contaminated with
industrial solvents. Permeability tests performed on the back-
filled material achieved the goal of 1 x 10'7 cm/sec or less
Associated activities at the site included the rerouting of under-
ground utilities, construction of 3-foot-high earthen berms
around all work areas, construction of two bentonite slurry
storage ponds ,and construction of three lined ponds capable
of storing 300,000 gallons of storm water. A ground water
extraction and stripping/filtration system is also in place at the
site. The slurry wall, purposely, was not keyed into an aquitard
so that the ground water extraction program would create an
upward gradient, thus serving to further contain the contami-
nants. The system appears to be functioning properly with the
implementation of the combination of the technologies [17]
[18]. However, this is the exception rather than the rule.
Technology Status
The construction and installation of slurry walls is consid-
ered a well-established technology. Several firms have experi-
ence in constructing this technology. Similarly, there are several
vendors of geosynthetic materials, bentonitic materials, and
proprietary additives for use in these barriers.
In EPA's FY 1989 ROD Annual Report [19] 26 RODs speci-
fied slurry walls as part of the remedial action. Of the RODs
specifying slurry walls, 22 also indicated that covers would be
used. Table 3 presents the status of selected superfund sites
employing slurry walls.
While site-specific geophysical and engineering studies (e g
compatibility testing of ground water and backfill materials) are
needed to determine the appropriate materials and construc-
tion specifications, this technology can effectively isolate wastes
and contain migration of hazardous constituents. Slurry walls
also may be implemented rather quickly in conjunction with
other remedial actions. Long-term monitoring is needed to
evaluate the effectiveness of the slurry wall.
EPA Contact
Technology-specific questions regarding slurry walls may
be directed to: y
Mr. Eugene Harris
U.S. Environmental Protection Agency
Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Cincinnati, Ohio 45268
(513)569-7862
Acknowledgements
This bulletin was prepared for the U.S. Environmental Pro-
tection Agency, Office of Research and Development (ORD),
Risk Reduction Engineering Laboratory (RREL), Cincinnati, Ohio'
by Science Applications International Corporation (SAIC) under
contract No. 68-C8-0062. Mr. Eugene Harris served as the EPA
Technical Project Monitor. Mr. Gary Baker was SAIC's Work
Assignment Manager. This bulletin was written by Mr. Cecil
Cross of SAIC. The author is especially grateful to Mr. Eric Saylor
of SAIC who contributed significantly during the development
of the document.
The following contractor personnel have contributed
their time and comments by participating in the expert review
meetings and/or peer reviewing the document:
Dr. David Daniel
Dr. Charles Shackelford
Ms. Mary Boyer
University of Texas
Colorado State University
SAIC
Engineering Bulletin: Slurry Walls
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Table 3
Selected Superfund Sites Employing Slurry Walls (19)
SITE
Ninth Avenue Dump
Outboard Marine
Liquid Disposal
Industrial Waste Control
E.H. Shilling Landfill
Allied/lronton Coke
Florence Landfill
South Brunswick
Sylvester
Waste Disposal Engineering
Diamond Alkali
Hooker - 1 02nd St.
Scientific Chemical Processing
Location (Region)
Gary, IN (5)
Waukegan, IL (5)
Utica, Ml (5)
Fort Smith, AR (6)
Ironton, OH (5)
Ironton, OH (5)
Florence Township, NJ (2)
New Brunswick, Nj (2)
Nashua, NH (1)
Andover, MN (5)
Neward, NJ (2)
Niagra Falls, NY (2)
Carlstadt, Nj (2)
Status
In design phase
In operation
In design phase
In operation since 3/91
In design phase
In pre-design phase
Design completed; remedial action
beginning soon
In operation since 1 985
In operation since 1983
In design phase
In pre-design phase
In remedial design phase
Completed 1992
REFERENCES
1. Gray, Donald H. and Weber, Walter J. Diffusional
Transport of Hazardous Waste Leachate Across Clay
Barriers. Seventh Annual Madison Waste Conference,
Sept. 11-12, 1984.
2. Technology Screening Guide for Treatment of CERCLA
Soils and Sludges. EPA/540/2-88/004. U.S. Environmen-
tal Protection Agency. 1988.
3. Slurry Trench Construction for Pollution Migration
Control. EPA-540/2-84-001. U.S. Environmental
Protection Agency. February 1984.
4. Waste Containment: Soil-Bentonite Slurry Walls. NEESA
Document No. 20.2-051.1, November 1991.
5. Ryan, C.R. Vertical Barriers in Soil for Pollution Contain-
ment. Presented at the ASCE-GT Specialty Conference-
Geotechnical Practice for Waste Disposal. Ann Arbor,
Michigan. June 15-17, 1987.
6. Bergstrom, Wayne R., Gray, Donald H. Fly Ash Utilization
in Soil-Bentonite Slurry Trench Sutoff Walls. Presented at
the Twelfth Annual Madison Waste Conference, Sept. 20-
21,1989.
7. Gray, D.H., Bergstrom, W.R., Mott, H.V., and Weber, W.j.
Fly Ash Utilization in Cuttoff Wall Backfill Mixes. Proceed-
ings from the Ninth Annual Symposium, Orlando, FL,
January 1991.
8. Gundle Lining Systems, Inc. Geolock Vertical Watertight
Plastic Screen for Isolating Ground Contamination.
Marketing Brochure. 1991.
9. Geo-Con, Inc. Deep Soil Mixing, Case Study No. 1.
Marketing Brochure. 1989.
10. Geo-Con, Inc. Deep Draining Trench By the Bio-Polymer
Slurry Trench Method, Technical Brief. Marketing
Brochure. 1991.
11. Hanford, R.W. and S.W. Day. Installation of a Deep
Drainage Trench by the Bio-Polymer Slurry Drain
Technique. Presented at the NWWA Outdoor Action
Conference, Las Vegas, Nevada. May 1988.
12. Handbook - Remedial Action at Waste Disposal Sites
(Revised). EPA-625/6-85/066. U.S. Environmental
Protection Agency. 1985.
Engineering Bu/fefin: Slurry Walls
*U.S. Government Printing Office: 1992 — 6*8-080/60082
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13. Technological Approaches to the Cleanup of Radiologi-
cally Contaminated Superfund Sites. EPA/540/2-88/002.
U.S. Environmental Protection Agency. August 1988.
14. Dalpais, E.A., E. Heyse, and W.R. James. Overview of
Contaminated Sites at Hill Air Force Base, Utah, and Case
History of Actions Taken at Landfills No. 3 and 4, Chem.
Pits 1 and 2. Utah Geol. Assoc. Publication 1 7. 1989.
15. U.S. Environmental Protection Agency. On-site FS for
Lipari Landfill, Final Draft Report. Prepared for U.S. EPA by
CDM, Inc. et al. August 1985.
16. Ceo-Con, Inc. Slurry Walls, Case Study No. 3, Marketing
Brochure. 1990.
17. GKN Hayward Baker, Inc. Case Study Slurry Trench Cut-
off wall, Raytheon Company, Mountain View, CA.
Marketing Brochure. 1988.
18. Burke, G.K. and F.N. Achhomer, Construction and Quality
Assessment of the In Situ Containment of Contaminated
Grounelwater. In Proceedings of the 5th National
Conference on Hazardous Wastes and Hazardous
Materials. April 1988.
19. ROD Annual Report: FY 90. EPA/540/8-91/067. U.S.
Environmental Protection Agency. July 1991.
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
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