United States
Environmental Protection
^gency
Solid Waste and
Emergency Response
(5102W)
EPA542-K-94-004
April 1995
In Situ Remediation
Technology Status Report:
Treatment Walls
Surfactant
Biological agent
Reducing or oxidizing algerjt
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EPA542-K-94-004
April 1995
In Situ Remediation Technology Status Report:
Treatment Walls
U.S. Environmental Protection Agency
Office of Solid Waste and Emergency Response
Technology Innovation Office
Washington, DC 20460
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Acknowledgements
The authors would like to thank all the researchers and technology developers described in this report for
their assistance in its preparation. We especially would like to thank Steve McCutcheon at the U.S. EPA
Environmental Research Laboratory in Athens, Georgia; Robert Puls at the U.S. EPA Robert S. Kerr
Environmental Research Laboratory in Ada, Oklahoma; and Stephen Shoemaker at DuPont Engineering
for reviewing the draft document and making valuable suggestions for improvement.
For more information about this project, contact:
Rich Steimle
U.S. Environmental Protection Agency (5102W)
Technology Innovation Office
401M Street, SW
Washington, DC 20460
703-308-8846
Notice
This material has been funded by the United States Environmental Protection Agency under contract
number 68-W2-0004. Mention of trade names or commercial products does not constitute endorsement or
recommendation for use.
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Foreword
The purpose of this document is to describe recent field demonstrations, commercial applications, and
research on technologies that either treat soil and ground water in place or increase the solubility and
mobility of contaminants to improve their removal by pump-and-treat remediation. It is hoped that this
information will allow more regular consideration of new, less costly, and more effective technologies to
address the problems associated with hazardous waste sites and petroleum contamination.
This document is one in a series of reports on demonstrations and applications of in situ treatment
technologies. To order other documents in the series, contact the National Center for Environmental
Publications and Information at (513) 489-8190 or fax your request to NCEPI at (513) 489-8695. Refer to
the document numbers below when ordering.
EPA542-K-94-003 Surfactant Enhancements
EPA542-K-94-004 Treatment Walls
EPA542-K-94-005 Hydraulic/Pneumatic Fracturing
EPA542-K-94-006 Cosolvents
EPA542-K-94-007 Electrokinetics
EPA542-K-94-009 Thermal Enhancements
Walter W. Kovalick, Jr., Ph.D.
Director, Technology Innovation Office
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Contents
Introduction 1
Purpose and Process 1
Technology Needs 1
Technology Descriptions 1
Completed Demonstrations 2
Waterloo Centre for Groundwater Research 2
Waterloo Centre for Groundwater Research 3
Ongoing and Future Demonstrations 4
Waterloo Centre for Groundwater Research 4
EnviroMetal Technologies and Waterloo Groundwater Control
Technologies 5
EnviroMetal Technologies 6
Waterloo Centre for Groundwater Research 7
Battelle Pacific Northwest Laboratories 8
Barrier Membrane Corporation 8
U.S. EPA Environmental Research Laboratory 9
Waterloo Centre for Groundwater Research 10
GEOCHEM (A Division of Terra Vac) 11
Current Research 12
ManTech Environmental Research Services Corporation and U.S. EPA
Environmental Research Laboratory, Ada, OK 12
U.S. EPA, Environmental Research Laboratory, Athens, GA 13
U.S. EPA, Environmental Research Laboratory, Athens, GA 15
U.S. EPA, Environmental Research Laboratory, Athens, GA 16
Battelle Pacific Northwest Laboratories 16
Oregon Graduate Institute of Science and Technology 17
Rust Geotech, Inc 18
New Mexico Institute of Mining and Technology 19
Department of Civil Engineering, Stanford University 20
Martin Marietta Energy Systems and Oak Ridge National Laboratory 21
GE Corporate Research and Development 22
Waterloo Centre for Groundwater Research 23
Los Alamos National Laboratory 24
General References 26
in
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Abbreviations
BTEX = Benzene, Toluene, Ethylbenzene, Xylene
CERCLA = Comprehensive Environmental Response, Compensation, and Liability Act
DCE = Dichloroethene
DNAPL = Dense Non-Aqueous Phase Liquid
DOE = Department of Energy
PAH = Poly-Aromatic Hydrocarbon
PCE = Tetrachloroethylene
RCRA = Resource Conservation and Recovery Act
SITE = Superfund Innovative Technology Evaluation Program
SVE = Soil Vapor Extraction
SVOC = Semi-Volatile Organic Compound
TCA = 1,1,1-Trichloroethane
TCE = Trichloroethylene
TPH = Total Petroleum Hydrocarbon
VOC = Volatile Organic Compound
IV
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Introduction
Purpose and Process
The purpose of this document is to describe demonstrations, field applications, and research on treatment
walls for remediating contaminated ground water at waste disposal and spill sites.
Information for this report came from computerized databases such as the Dialog Information Services and
the Environmental Protection Agency's (EPA) Vendor Information System for Innovative Treatment
Technologies (VISITT) and Alternative Treatment Technologies Information Center (ATTIC). Additional
materials were obtained from publications such as the Hazardous Substance Research Center Annual
Reports, Superfund Innovative Technology Evaluation Technology Profiles and Department of Energy's
Office of Technology Development Program Summary as well as conference summaries, proceedings and
compendiums. Personal interviews and discussions with representatives of other federal agencies,
academic research centers, and hazardous waste remediation consulting firms provided supplementary
information.
Technology Needs
Numerous hazardous waste sites have significant concentrations of metals, halogenated organic
compounds, and radionuclides that contaminate ground water. Traditional technologies, such as pump and
treat, require an external energy source and their cost is high. Subsurface residuals frequently remain at
undesirable levels. Thus, subsurface permeable treatment walls are being considered as a cost-effective in
situ water treatment alternative.
Technology Descriptions
Water permeable treatment walls are installed as permanent, semi-permanent, or replaceable units across
the flow path of a contaminant plume, allowing the plume to move passively through while precipitating,
sorbing, or degrading the contaminants. These mechanically simple barriers may contain metal-based
catalysts for degrading volatile organics, chelators for immobilizing metals, nutrients and oxygen for
microorganisms to enhance bioremediation, or other agents. Degradation reactions break down the
contaminants in the plume into harmless byproducts. Precipitation barriers react with contaminants to form
insoluble products that are left in the barrier as water continues to flow through. Sorption barriers adsorb
or chelate contaminants to the barrier surface. The reactions that take place in barriers are dependent on
parameters such as pH, oxidation/reduction potential, concentrations, and kinetics. Thus, successful
application of the technology requires characterization of the contaminant, ground-water flux, and
subsurface geology. Although most barriers are designed to operate in situ for years with minimal
maintenance and without an external energy source, the stability of aging barriers has not been established.
The following pages contain descriptions of completed, ongoing, and future demonstrations and
commercial applications as well as current research and testing of passive treatment walls.
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Completed Demonstrations
Canadian Forces Base Borden, Ontario, Canada
Waterloo Centre for Groundwater Research, University of Waterloo
In Situ Permeable Reaction Wall
Description of Demonstration: Researchers installed a permeable reaction wall containing an iron-based
catalyst about 16.5 feet downgradient from the source of a contaminant plume to pilot test the capability of
the wall to degrade halogenated organic compounds. The plume was about 6.5 feet wide and 3.3 feet thick
with maximum concentrations along the axis of about 250,000 //g/L trichloroethene (TCE) and 43,000
//g/L tetrachloroethene (PCE). The source of the plume was located about 13 feet below ground surface
and 3.3 feet below the water table. (Investigators believe the wall can be installed to depths of 50 feet, but
no test results are available at this time to substantiate this.)
Using scalable joint sheet piling, a rectangular cell was constructed on the surface and driven to a depth of
32 feet, the cell was sealed and dewatered and the native sand was replaced by the reactive material
consisting of'22% by weight granular iron and 78% by weight course sand. The sand, which was coarser
than the native materials, ensured that the wall would be more permeable than the surrounding sand. After
installing the reactive material, the sheet piling was completely removed and natural flow conditions were
achieved. The wall dimensions were 18 feet long, 5.2 feet thick, and 7.2 feet deep and it was positioned
3.3 feet below the water table.
Wastes Treated: VOCs
Status: The pilot test was completed in 1993. The Waterloo Centre for Groundwater Research is part of
Ontario's Centres of Excellence program, a government sponsored partnership with academia and
industry.
Demonstration Results: Multilevel monitoring wells were located 1.6 feet upgradient of the wall, in the
wall at distances of 1.6 and 3.3 feet, and 1.6 feet downgradient of the wall for a total of 348 sampling
points. Concentration distributions through the wall were determined on 13 occasions over 474 days,
during which there was no decline in the effectiveness of the barrier. Most of the mass loss occurred
within the first 50 cm of the wall; at greater distances into the wall, performance was below that expected.
However, the reaction wall reduced the TCE concentration by 95% and the PCE concentration by 91%.
No vinyl chloride was detected in the samples. Increased chloride concentrations downstream of the wall
were consistent with the quantity of TCE and PCE that had been degraded. Only trace amounts of
dichloroethene (DCE) were detected downstream of the wall.
Contacts:
Stephanie F. O'Hannesin
Waterloo Centre for Groundwater Research
University of Waterloo
Waterloo, Ontario N2L 3G1 Canada
519-885-1211x3159
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References:
O'Hannesin, S.F. A Field Demonstration of a Permeable Reaction Wall for the In Situ Abiotic
Degradation ofHalogenated Aliphatic Organic Compounds. Master's Thesis, University of Waterloo,
Waterloo, Ontario, Canada. 1993.
O'Hannesin, S.F. and Gillham, R.W. "A Permeable Reaction Wall for In Situ Degradation of Halogenated
Organic Compounds." 45th Canadian Geotechnical Society Conference, Toronto, Ontario, October 25-28,
1992.
O'Hannesin, S.F. and Gillham, R.W. "In Situ Degradation of Halogenated Organics by Permeable
Reaction Wall." Ground Water Currents, March 1993, EPA/542/N-93/003.
Borden Aquifer, Ontario, Canada
Waterloo Centre for Groundwater Research, University of Waterloo
In Situ Permeable Reaction Wall
Description of Demonstration: Researchers field tested a proprietary solid peroxide formulation (an
oxygen-releasing compound) to determine whether it could provide dissolved oxygen in a controlled
steady manner to enhance biodegradation of BTEX-contaminated ground water. Benzene and toluene
were injected into ground water to represent BTEX compounds, and their fate was monitored over several
weeks along four lines of monitoring wells.
Wastes Treated: BTEX
Status: Completed.
Demonstration Results: The results indicate that the oxygen releasing compound can support
biodegradation of benzene and toluene at concentrations typical of those found at petroleum contaminated
sites.
Contacts:
Stephanie F. O'Hannesin
Waterloo Centre for Groundwater Research
University of Waterloo
Waterloo, Ontario N2L 3G1 Canada
519-885-1211
References:
Bianchi-Mosquera, G.C.; Allen-King, R.M.; and Mackay, D.M. "Enhanced Degradation of Dissolved
Benzene and Toluene Using a Solid Oxygen-Releasing Compound" Ground Water Monitoring and
Remediation, Winter 1994, p 120-128.
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Ongoing and Future Demonstrations
Canadian Forces Base Borden
Waterloo Centre for Groundwater Research, University of Waterloo
In Situ Permeable Reaction Wall
Description of Demonstration: Researchers are field testing an in situ semipassive permeable wall into
which nutrient solutions that enhance biodegradation of organics are introduced. The wall is installed
across the path of a contaminant plume in an unconsolidated aquifer.
Wastes Treated: TCE, carbon tetrachloride
Status: Ongoing
Demonstration Results: Results indicate that by adding substances in the wall, the mixing with ground
water is maximized to produce a stable microbial population that can be supported at some distance
downgradient from the wall. An anaerobic population supporting this led to complete carbon tetrachloride
removal from ground water, but did not transform TCE. Work is continuing to overcome this limitation.
Contact:
Stephanie F. O'Hannesin
Waterloo Centre for Groundwater Research
University of Waterloo
Waterloo, Ontario N2L 3G1 Canada
519-885-1211
Reference:
Devlin, J.F. and Barker, J.F. "A Semipassive Nutrient Injection Scheme for Enhanced In Situ
Bioremediation." Ground Water, 32 (3), 1994, p 374.
General Electric, Sunnyvale, California
EnviroMetal Technologies
Metal-Enhanced Abiotic In Situ Treatment of VOCs
Description of Demonstration: An above-ground field test reactor containing 50% iron was installed at
this semiconductor manufacturing facility to test the feasibility of installing an in situ permeable reactive
zone. Ground water was pumped through the reactor at a rate of 4 feet/day for 9 months. Initial
concentrations of contaminants were 50-200 ppb trichloroethene (TCE), 450-1000 ppb cis-1,2-
dichloroethene (cis-DCE), 100-500 ppb vinyl chloride (VC), and 20-60 ppb Freon-113. The time required
to degrade one-half of the contaminant mass in the above-ground field test was <1.7 hours for TCE, 1-4
hours for cis-DCE, 2-4 hours for VC, and < 1.6 hours for Freon-113. Mineral precipitation, hydrogen gas
production, and microbial effects also were evaluated.
Wastes Treated: TCE, DCE, vinyl chloride, Freon-113
Status: Based on the feasibility tests described above, a full-scale in situ permeable treatment wall was
approved by the state regulatory agency and was installed in December 1994. The permeable reactive
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zone, which will be 4 feet thick, 40 feet long, 10 feet high, and about 25-30 feet deep, will contain 100%
reactive iron. It will be installed using a trench box design. The estimated cost is projected to be $175,000-
$200,000. Patents governing the in situ application of the metal enhanced dehalogenation are held by the
University of Waterloo. EnviroMetal Technologies, Inc. holds an exclusive license with the University of
Waterloo for this treatment technology.
Demonstration Results: None yet
Contact:
John Vogan
EnviroMetal Technologies, Inc.
42 Arrow Road
Guelph, Ontario NIK 1S6 Canada
519-824-0432
Reference:
Gillham, R.W. and O'Hannesin, S.F. "Metal Catalyzed Abiotic Degradation of Halogenated Organic
Compounds." Ground Water, 29 (5), 1991, p 752.
Industrial Facility, New York State
EnviroMetal Technologies and Waterloo Groundwater Control Technologies
Metal-Enhanced Abiotic In Situ Treatment of VOCs
Using Funnel-and-Gate™ System
Description of Demonstration: VOCs will be degraded using the EnviroMetal process (metal-enhanced
reductive dehalogenation) in a pilot-scale Funnel-and-Gate™ in situ treatment system at a former plating
facility contaminated with chlorinated solvents. The reactive zone, containing 100% granular iron, will be
10 feet wide, 3 feet thick, and installed at a depth of 15 feet, which is below the water table and near the
source of the contaminant plume. Ground water will be directed towards the zone by 15 linear feet of
Waterloo Barrier sheetpiling on either side. There is a confining layer of clay at 15 feet.
Wastes Treated: VOCs and SVOCs, including TCE, PCE, DCE, and vinyl chloride
Status: A pilot-scale unit was installed in May 1995. After the system is operating, the demonstration is
expected to run for 6 months. The New York State Department of Environmental Conservation and U.S.
EPA's SITE program are overseeing the demonstration. EnviroMetal Technologies Inc. holds an exclusive
license with the University of Waterloo, the patent holder, for the commercial application of this treatment
technology. Waterloo Groundwater Control Technologies, Inc. is commercializing the Funnel-and-Gate™
system (patents pending) developed at the Waterloo Centre for Groundwater Research.
Demonstration Results: None yet
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Contacts:
John Vogan
EnviroMetal Technologies, Inc.
42 Arrow Road
Guelph, Ontario NIK 1S6 Canada
519-824-0432
Robin Jowett
Waterloo Groundwater Control Technologies, Inc.
P.O. Box 385
Rockwood, Ontario NOB 2KO Canada
519-856-1352
Reference:
Gillham, R.W. and O'Hannesin, S.F. "Metal Catalyzed Abiotic Degradation of Halogenated Organic
Compounds." Ground Water, 29 (5), 1991, p 752.
Semiconductor Manufacturing Facility, New Jersey
EnviroMetal Technologies
Metal-Enhanced Abiotic In Situ Treatment of VOCs
Description of Demonstration: Batch and column tests using 50% and 100% iron in the reactive media
and ground water flowing at 1.5 feet/day were conducted to establish reaction conditions for a pilot-scale
above-ground field trial (now underway). These tests are for the future installation of an in situ treatment
wall.
Wastes Treated: TCE, PCE, DCE, vinyl chloride
Status: An above-ground field trial began in November 1994 under the EPA SITE demonstration program
and is still operating. The field trial results should be published by the end of 1995.
Additional sites where feasibility studies have been completed or are underway include:
• Twin Cities Army Ammunition Plant in St. Paul, Minnesota (sponsored by the Minnesota Pollution
Control Agency) to treat TCE, PCE, and cis-l,2-dichloroethene
• Closed landfill in New Mexico
• Industrial facilities in Massachusetts, California, and New York
• Air Force facilities in Utah and Washington State (large-scale field tests scheduled to occur in 1995 at
Hill AFB, Utah, will involve the use of a funnel-and-gate system with the iron filings to treat TCE)
Demonstration Results: Results are not yet available. The column test results showed half-life
degradation rates of 0.7 hours for PCE (4000 to 12000 ppb initially) at 50% iron and 0.4 hours at 100%
iron; and for TCE (400 to 1000 ppb initially) 1.1 hours at 50% iron and 0.5 hours at 100% iron.
Contact:
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John Vogan
EnviroMetal Technologies, Inc.
42 Arrow Road
Guelph, Ontario NIK 1S6 Canada
519-824-0432
Reference:
Gillham, R.W. and O'Hannesin, S.F. "Metal Catalyzed Abiotic Degradation of Halogenated Organic
Compounds." Ground Water, 29 (5), 1991, p 752.
AFB/Massachusetts Military Reserve, Falmouth, Massachusetts
Waterloo Centre for Groundwater Research, University of Waterloo
Metal-Enhanced Abiotic Treatment of VOCs Using a Funnel-and-Gate™
Description of Demonstration: A pilot-scale test using granular iron in a Funnel-and-Gate™ system is
planned to treat a large and deep contaminant plume containing VOCs. The system will be installed near
the leading edge of the plume, which is 40 to 100 feet thick and 180 feet deep.
Wastes Treated: VOCs
Status: A preliminary test was conducted in the spring of 1995.
Demonstration Results: The test failed to reach the 180 foot depth. Consequently, the reaction zone and
Funnel-and-Gate™ system will not be pilot tested on that deep plume. Other options for the deep plume
are under consideration by the National Guard, who is sponsoring the demonstration. The reaction zone
and Funnel-and-Gate™ system may be tested on two other, more shallow, plumes at the site.
Contact:
Stephanie O'Hannesin
Waterloo Centre for Groundwater Research
University of Waterloo
Waterloo, Ontario N2L 3G1 Canada
519-885-1211x3159
Reference:
Gillham, R.W. and O'Hannesin, S.F. "Metal Catalyzed Abiotic Degradation of Halogenated Organic
Compounds." Ground Water, 29 (5), 1991, p 752.
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Hanford 100D Area, Washington
Battelle Pacific Northwest Laboratories
In Situ Redox Manipulation Project
Description of Demonstration: Field experiments are planned for the Arid Soils VOC Integrated
Demonstration to test the feasibility of in situ redox manipulations with chemical reagents using a forced
gradient, single well, reactive tracer test. Field experiments will involve injecting the reagent sodium
dithionite into the aquifer creating a 60 to 100 foot diameter geochemical barrier in advance of a
contaminant plume. After allowing 5 to 30 days for the reaction to occur, water containing the reaction
byproducts and any remaining reagent will be pumped out. The longevity of the system to maintain a
reducing environment also will be evaluated.
Wastes Treated: Chromium
Status: The demonstration is scheduled for summer 1995. The researchers have conducted an initial site
characterization using existing monitoring wells and have submitted a draft test plan to DOE, EPA, and
the State of Washington Department of Ecology. The Department of Energy is sponsoring the research.
Contact:
J.S. Fruchter
Battelle Pacific Northwest Laboratories
Battelle Boulevard
P.O. Box 999
Richland, WA 99352
509-376-3937
Reference:
Fruchter, J.S. In Situ Redox Manipulation: Enhancement of Contaminant Destruction and Immobilization.
Semi-Annual Office of Technology Development (OTD) Information Meeting (2nd), Houston, Texas,
January 26-28, 1993, NTIS Order Number DE93007877, 7p.
DOE Savannah River, South Carolina
Barrier Membrane Corporation
Treatment Wall
Description of Demonstration: Researchers are constructing a gravel trench 300 feet long by 30 feet deep
that will intersect the highest contaminant concentration of a contaminant plume. Pumping wells will be
constructed within this wall to remove contaminated ground water but the major focus is to study the
hydraulics. The studies are designed to investigate ground-water retention time in the wall and problems
associated with injecting a treatment medium in the gravel matrix. The contaminant plume is shallow and
the surrounding soils are interbedded clays and sands.
Wastes Treated: Chromium, nickel, lead and cadmium
Status: Under construction. Pump tests are scheduled for July and August 1995.
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Contact:
Mark Phifer
Westinghouse SRC/SRS
Building 773-42A
Aiken, SC 29808
803-725-5222
Fax: 803-725-7673
Coast Guard Air Station, Elizabeth City, North Carolina
U.S. EPA Environmental Research Laboratory, Ada, OK
Treatment Wall
Description of Demonstration: A series of large-diameter augered holes in a staggered 3-row array were
located within an aquifer to intercept a contaminant plume of chromate and chlorinated organics. A
mixture (by volume) of 50% iron filings (two types), 25% clean coarse sand, and 25% aquifer material
was poured down hollow-stem augers from 22 feet to 10 feet below ground surface. Each iron column was
approximately 8 inches in diameter and a total of twenty-one columns were installed in a 60 square foot
area. The mixed waste contaminant plume is between 14 and 20 feet below ground surface and the water
table ranges from 5 to 6 feet below ground surface. One iron type was shown to be an effective reductant
for chromate in a two-year laboratory study by RSKERL scientists, while the other iron has been shown to
be more effective in the reductive dechlorination of the organics. This field experiment is evaluating the
effectiveness of this method of treatment wall emplacement and is providing additional in situ field data
for full field-scale implementation.
Wastes Treated: TCE, DCE, vinyl chloride, and Cr+6
Status: The demonstration has been in operation since September 1994.
Preliminary Results: Preliminary results show complete reduction of Cr+6to below detection (<0.01 mg/
L) limits and greater than 75% reduction in initial TCE concentrations and reduction of vinyl chloride
concentrations to less than 1 //g/L. These results are very promising, especially for the chlorinated
organics, because the experiment was primarily designed to optimized chromate remediation, not the
chlorinated organics. Longer residence times are planned for the latter in the full field scale test to be
installed in August 1995.
Contact:
Bob Puls
U.S. EPA
Robert S. Kerr Environmental Research Laboratory
Box 1198
Ada, OK 74820
405-436-8543
References:
Puls, R.W.; Powell, R.M.; and Paul, C.J. "In Situ Remediation of Ground Water Contaminated with
Chromate and Chlorinated Solvents Using Zero-Valent Iron: A Field Study. "Proceedings of the 209th
American Chemical Society National Meeting, Anaheim, California, April 2-7, 1995. 35 (1), p 788-791.
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Several Sites in Canada and the United States
Waterloo Centre for Groundwater Research
In Situ Permeable Reaction Wall for Treatment of Inorganics
Description of Demonstration: Inorganic contaminants in ground water are treated using in situ porous
reactive walls. Wall materials are placed in the path of the plume and react with the contaminant via
reduction and precipitation. This technology is being developed for treating mine and industrial wastes,
and septic system and agricultural effluent.
Wastes Treated: Inorganics, especially metals, SO4and PO4 radionuclides
Status: Field trials are ongoing to remove dissolved Cr, Fe, SO4and PO4
Results: Preliminary results indicate contaminant concentrations are decreased by orders of magnitude and
to below drinking water levels.
Contacts:
D.W. Blowes
Waterloo Centre for Groundwater Research
University of Waterloo
Waterloo, Ontario, Canada
519-888-4878
Fax:519-746-5644
C.J. Ptacek
Waterloo Centre for Groundwater Research
University of Waterloo
Waterloo, Ontario, Canada
519-885-1211x2230
Fax:519-746-5644
References:
Blowes, D.W. and Ptacek, C.J. "Geochemical Remediation of Groundwater by Permeable Reactive Walls:
Removal of Chromate by Reaction with Iron-Bearing Solids. "Proceedings of the Subsurface Restoration
Conference, Third International Conference on Groundwater Quality Research, June 21-24, 1992, Dallas,
Texas, p 214-216.
Blowes, D.W. and Ptacek, C.J. System for Treating Contaminated Groundwater (Redox Curtain). United
States Patent 5,362,394. 1994.
Blowes, D.W.; Ptacek, C.J.; Bain, J.G.; Waybrant, K.R; and Robertson, W.D. "Treatment of Mine
Drainage Water Using In Situ Permeable Reactive Walls." Proceedings of the Sudbury 1995 Mining and
the Environment Conference, May 28-June 1, 1995, Sudbury, Ontario.
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Valley Wood Treating, Turlock, California
In Situ Remediation of Chromium in Ground Water
GEOCHEM (A Division of Terra Vac)
Description of Technology Use: The process removes chromium from contaminated ground water using
a variation of traditional pump-and-treat methods. Contaminated ground water is brought to the surface
and treated using conventional treatment systems such as ferrous iron. A reductant is added to the treated
water which is reinjected around the plume margin where it reacts and reduces residual levels of
chromium, forming a precipitate. Such reinjection creates a "barrier" of elevated water levels around the
plume, enhancing the gradient and associated hydraulic control. The reinjection also allows for in situ
reduction and subsequent fixation of residual chromium.
Wastes Treated: Cr+6
Status of Demonstration and Development: The technology was accepted into the SITE Program in the
summer of 1992. Arrangements are being made to demonstrate the technology in 1995.
Demonstration Results: None yet.
Contacts:
Douglas Grosse
U.S. EPA
National Risk Management Research Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
513-569-7844
Fax:513-569-7676
Jim Rouse
GEOCHEM (A division of Terra Vac)
12596 West Bayaud, Suite 205
Lakewood, CO 80228
303-988-8902
Fax: 303-988-0288
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Current Research
Reaction Mechanisms in Permeable Reactive Barriers
ManTech Environmental Research Services Corporation and U.S. EPA
Environmental Research Laboratory, Ada, OK
Description of Research: Research during the past three years has evaluated the impact of subsurface
geochemistry and mineralogy on chromate reduction by zero-valent metals in permeable reactive barriers.
When reduced from Cr(VI) to Cr(III) the chromium becomes less toxic and its mobility is reduced due to
precipitation and adsorption, effectively remediating the aquifer. This research had multiple objectives,
which were to determine:
1) whether corrosion processes, including cathodic reduction, are responsible for the removal of solution
CrO42" by elemental metals, primarily iron,
2) if removal would occur in systems incorporating aquifer materials,
3) the rates and mechanisms of the CrO42" removal,
4) the form and location of the removed chromium,
5) how iron type, geochemical, and mineralogical differences affect these reactions and,
6) whether this remediation approach is suitable for a CrO42"plume at the U.S. Coast Guard Air Support
Center, Elizabeth City, North Carolina.
Numerous stirred batch reactor and shaken batch bottle experiments to test chromate reduction have been
performed using two different aquifer sediments and a silica sand, seven types of iron, titanium,
magnesium, aluminum, various metal pretreatments and seven aluminosilicate minerals. Aluminosilicate
dissolution in these systems has also been evaluated. Chromate adsorption and desorption studies as well
as electron probe microscopic analyses of the reacted materials have been carried out.
The results have shown that CrO42" in solution can be reduced to Cr(III) by corrosion mechanisms in the
presence of elemental iron. The rate and completeness of chromate reduction are dependent on a complex
interaction between metal type, mass, surface area, pretreatment, and aquifer material mineralogy.
Exploratory data analysis was performed across several variables for one iron and aquifer material system
that reduced chromate rapidly. The resulting multiple regression model showed that 94% of the variation
in the chromate reduction half-life was explained by the iron mass and solid:solution ratio.
These corrosion reactions can only proceed when suitable e" acceptors, such as protons, are present to form
an appropriate couple and prevent the accumulation of electric charge. An electrical double-layer model
analogue for the metal filing surface has been proposed to explain the reactions that occur. Some types of
iron, particularly impure and partially corroded forms, are far more reactive than others for reducing CrO 42~
. Certain aquifer materials contribute more significantly to these reactions due to their mineralogy.
Aluminosilicates appear able to provide e" accepting protons through dissolution, maintaining the
corrosion process. A cycle can develop in which rust formation through corrosion promotes additional
aluminosilicate dissolution.
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Research is continuing on these topics for chromium, along with the potential for enhancing the
remediation of other metals using permeable reactive barriers.
Wastes Treated: Chromium
Contact:
Bob Puls, Ph.D.
U.S. Environmental Protection Agency
R.S. Kerr Environmental Research Laboratory
P.O. Box 1198
Ada, OK 74820
405-436-8543
References:
Powell, R.M. Geochemical Effects on Chromate Reduction and Remediation Utilizing the Thermodynamic
Instability of Zero-Valence-State Iron. Master's Thesis. University of Oklahoma, Norman, Oklahoma
1994.
Powell, R.M.; Puls, R.W.; Hightower, S.K.; Clark, D.A. "Corrosive and Geochemical Mechanisms
Influencing In Situ Chromate Reduction by Metallic Iron." American Chemical Society, Division of
Environmental Chemistry, Preprints of Papers Presented at the 209th ACS National Meeting, Anaheim,
California, April 2-7, 1995. 35 (1), p 784-787.
Powell, R.M.; Puls, R.W.; Hightower, S.K.; Sabatini, D.A. "Coupled Iron Corrosion and Chromate
Reduction: Mechanisms for Subsurface Remediation." In press for the August 1995 Environmental
Science and Technology.
Puls, R.W.; Powell, R.M.; Paul, C.J. "In Situ Remediation of Ground Water Contaminated with Chromate
and Chlorinated Solvents Using Zero-Valent Iron: A Field Study." American Chemical Society, Division
of Environmental Chemistry, Preprints of Papers Presented at the 209th ACS National Meeting, Anaheim,
California. April 2-7, 1995. 35 (1), p 788-791.
Powell, R.M.; Puls, R.W.; Paul, C.J. "Chromate Reduction and Remediation Utilizing the Thermodynamic
Instability of Zero-Valence-State Iron." Water Environment Federation Specialty Conference Series
Innovative Solutions for Contaminated Site Management. March 6-9, 1994, Miami, Florida.
Powell, R.M. and Puls, R.W. "Abiotic Reduction of Chromate from Zero-Valent Iron Dissolution:
Reaction Rates and the Effects of Aquifer Materials." Metal Speciation and Contamination of Aquatic
Sediments Workshop, Jekyll Island, Georgia, 1993.
In Situ Process Based on Zero-Valent Iron
U.S. EPA, Environmental Research Laboratory, Athens, GA
Description of Research: Stainless steel columns have been designed to address a number of unresolved
issues in applying reactive iron treatment walls. These columns provide a greater level of experimental
control than those typically being used in reactive iron pilot studies. The columns are designed to measure
pH and treatment efficiencies along the length of the column to understand why iron treatment walls lose
effectiveness after movement through 10 to 50 cm of media. Innovative iron mixtures are being tested to
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overcome pH problems and the inability to achieve drinking water standards and other MCLs. Long-term
stability testing is underway (3 to 6 months). Contaminated water from the DOE Savannah River Plant
TNX facility will be used for testing in concert with feasibility testing at the University of Waterloo. Data
from Waterloo/EnviroMetal pilot tests at Hill AFB have been reviewed, especially those tests where trace
amounts of vinyl chloride were observed. These data and results from column studies are being used to
develop preliminary guidance on the design and application of funnel-and-gate systems, and other reactive
wall configurations. Other efforts focus on the kinetics of the reaction.
Experiments are currently underway to identify and estimate the parameters that control the dechlorination
rate of trichloroethene and similar volatile organic compounds in flowing systems exposed to zero-valent
iron. These studies examine the effects of mass transfer on the observed conversion rates for various flow
velocities, pH, and contaminant concentrations. A rigorous description of the dependence of the
conversion rate on the system operating conditions facilitates the development and implementation of this
technology. Such detailed knowledge of the physical and chemical factors that control the degradation of
ground-water contaminants by granular iron will lead to improved designs of in situ treatment processes.
Potentiostatic and potentiodynamic electrochemical approaches are planned to investigate surface
coverage, sorbed species, effects of hydrogen formation, and the elementary rate determining step.
Wastes Treated: TCE, PCE, other chlorinated solvents
Contact:
Steven C. McCutcheon, Ph.D., P.E.
Ronald A. Holser, Ph.D.
U.S. EPA
Environmental Research Laboratory-Athens
960 College Station Road
Athens, GA 30605-2720
706-546-3160
Fax: 706-546-3340
Email: EPASM@Athens.ath.epa.gov orRholser@Athens.ath.epa.gov
References:
Holser, R.A.; McCutcheon, S.C.; Wolfe, N.L. "The Application of a Rate Expression for the Reductive
Dehalogenation of TCE-Contaminated Groundwater to the Design and Performance of a Funnel and Gate
System." Federal Environmental Restoration IVand Defense Cleanup Southeast, Atlanta, Georgia,
March 14-15, 1995.
Holser, R.A.; McCutcheon, S.C.; Wolfe, N.L. "Mass Transfer Effects on the Dehalogenation of
Trichloroethene by Iron/Pyrite Mixtures." Extended Abstract and Invited Presentation, Division of
Environmental Chemistry, American Chemical Society, Anaheim, California, April 2-7, 1995.
Reduction of Halogenated Hydrocarbons by Metallic Iron
U.S. EPA, Environmental Research Laboratory, Athens, GA
Description of Research: Kinetic studies have been conducted on the redox reactions of the common
ground-water contaminants, tetrachloroethene and trichloroethene in an effort to delineate the reaction
mechanism and to identify the degradation products. The dependence of the reaction rate on factors such
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as temperature, pH, iron surface area, oxygen concentration, and competing species has been investigated.
The focus of the work is to accurately predict the fate of these chlorinated pollutants and to investigate
new remediation methods. New reactive iron mixtures have been derived. This study was the first to
obtain a rigorous mass balance and pathway analysis of the reductive iron process. Firm hypotheses have
been obtained for the nature of the sorption reaction and dechlorination process. Some of the work has
been done in collaboration with David Burris of the Air Force Armstrong Laboratory located at Tyndall
Air Force Base, Florida.
Wastes Treated: PCE, TCE, other chlorinated solvents
Contact:
N.L. Wolfe, Ph.D.
U.S. EPA Environmental Research Laboratory
960 College Station Road
Athens, GA 30605-2720
706-546-3429
Fax: 706-546-3636
Email: Wolfe@Athens.ath.epa.gov
References:
Carreira, L. and Wolfe, N.L. "Abiotic Reductions: A Biochemical Approach." 23rd Annual Symposium
on Environmental-Analytical Chemistry, Jekyll Island, Georgia, June 14, 1993.
Cipollone, M.G.; Hassan, S.M.; Wolfe, N.L.; Burris, D.R.; Jeffers, P.M. in review. "Reduction of
Halogenated Hydrocarbons with Iron: I. Kinetic Observations."
Cipollone, M.G. and Wolfe, N.L. Extended Abstract and Invited Presentation, Division of Environmental
Chemistry, American Chemical Society, Anaheim, California, April 2-7, 1995.
Hatfield, K.; Burris, D.R.; Wolfe, N.L. "Heterogenous Reactions in Flow-Through Porous Media I.
Analytical Model." submitted to American Society of Civil Engineer's Journal of Environmental
Engineering.
Wolfe, N.L.; Carreira, L.; Burris, D. "Potential for In Situ Remediation of Dissolved Halogenated Solvents
Using Biochemical Redox Components." Second International Symposium on In Situ and On-Site
Bioremediation. San Diego, California, April 5-8, 1993.
Wolfe, N.L.; Peijnenburg, W.; d Hollander, H.; Verboom, H.; v d Meent, D. submitted for publication
"Structure Reactivity Relationships for Predicting Reductive Transformation Rate Constants of
Halogenated Hydrocarbons in Anoxic Sediment Systems." Environmental Toxicology and Chemistry,
1994.
Wolfe, N.L.; Peijnenburg, W.; d Hollander, H.; Verboom, H.; v d Meent, D. submitted for publication
"Kinetics of Reductive Transformations of Halogenated Hydrocarbons Under Anoxic Reaction
Conditions." Environmental Toxicology and Chemistry, 1994.
Dechlorination of Pesticides
U.S. EPA, Environmental Research Laboratory, Athens, GA
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Description of Research: The degradation of chlorinated pesticides by anaerobic bacteria and separately
by zero-valent metals is being studied. Sediment samples have been collected and compared to known
contaminated sediments to identify environmental factors that are responsible for anaerobic degradation.
These studies have focused on the combination of extraction and reaction to release the bound contaminate
from the soil matrix and degrade the solubilized compound. They are also designed to improve analytical
methods.
Wastes Treated: Toxaphene, chlordane, DDT and dieldrin
Contact:
N.L. Wolfe, Ph.D.
U.S. EPA
Environmental Research Laboratory-Athens
960 College Station Road
Athens, GA 30605-2720
706-546-3429
Fax: 706-546-3636
Email: Wolfe@Athens.ath.epa.gov
In Situ Redox Barriers
Battelle Pacific Northwest Laboratories
Description of Research: Researchers at Battelle Pacific Northwest Laboratories have been studying the
ability of different reagents and microbial nutrient systems to immobilize inorganics or destroy organics in
the ground water and solid materials of an unconfmed aquifer. The Department of Energy is sponsoring
the research.
In the laboratory studies, completed in 1994, microbes exhibited the ability to degrade carbon tetrachloride
and other chlorinated solvents when the redox potential was reduced to the point where nitrate or iron
instead of oxygen acts as an electron acceptor. Chromate could be immobilized by reduction to highly
insoluble chromium hydroxide or iron chromium hydroxide.
Bench-scale studies, completed in 1994, were intended to determine the nature of the reactions that occur
and the efficiency with which they are induced by reagents or nutrients. The potential of cultured iron-
reducing bacteria for remediating subsurface environments contaminated with carbon tetrachloride and
chromium has been tested, and sodium dithionite was found to reduce structural ferric iron in Hanford
soils, the planned area for a field demonstration. Further experiments indicate that the half-life of the
dithionite ion is about two or three days in the Hanford confined aquifer. This half-life is adequate for
reducing the contaminants in the plume, while ensuring that dithionite does not remain as a contaminant in
the ground water for an extended time.
Wastes Treated: Chromium, chlorinated solvents
Contact:
J.S. Fruchter
Battelle Pacific Northwest Laboratories
Battelle Boulevard
P.O. Box 999
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Richland, WA 99352
509-376-3937
Remediation with Zero-Valent Iron
Oregon Graduate Institute of Science and Technology
Description of Research: The primary purpose of the research is to explain how iron degrades
chlorinated solvents such as PCE, TCE, and carbon tetrachloride in ground water. Laboratory
experimental systems and columns have been used to study the reaction between chlorinated methanes and
their degradation by pure iron. The laboratory systems show that zero-valent iron participates in reductive
dechlorination predominantly by direct reduction at the iron surface, a process similar to metal corrosion.
Additional work has shown that iron reacts with nitro-aromatic groups, common in some types of
munitions like TNT. Researchers are investigating the many conditions and complicating factors that
affect remediation of chlorinated solvents and nitro-aromatic compounds using iron.
Wastes Treated: Chlorinated solvents, nitro-aromatic compounds
Contact:
Paul Tratnyek
Department of Environmental Science and Engineering
Oregon Graduate Institute of Science and Technology
P.O. Box 91000
Portland, OR 97291-1000
503-690-1023
References:
Agrawal, A. and Tratnyek, P.O. "Abiotic Remediation of Nitro-Aromatic Ground-Water Contaminants by
Zero-Valent Iron." Preprints of Papers Presented at the 207th ACS National Meeting in San Diego,
California, March 13-18, 1994. American Chemical Society, Division of Environmental Chemistry 34 (1),
1994, p 492-494.
Johnson, T.L. and Tratnyek, P.O. "A Column Study of Carbon Tetrachloride Dehalogenation by Iron
Metal." Proceedings of the 33rdHanford Symposium on Health & the Environment—In Situ Remediation:
Scientific Basis for Current and Future Technologies. Pasco, Washington, 1994, p 931-947.
Matheson, L.J. and Tratnyek, P.O. "Processes Affecting Reductive Dechlorination of Chlorinated Solvents
by Zero-Valent Iron." Preprint of Papers Presented at the 205th ACS National Meeting in Denver,
Colorado, March 28-April 2, 1993. American Chemical Society, Division of Environmental Chemistry,
33, p 3-4.
Matheson, L.J. and Tratnyek, P.G. "Reductive Dehalogenation of Chlorinated Methanes by Iron Metal."
Environmental Science and Technology, 28 (12), 1994, p 2045-2053.
Matheson, L.J. and Tratnyek, P.G. "Abiotic and Biotic Aspects of Reductive Dechlorination of
Chlorinated Solvents by Zero-Valent Iron." Preprints of Papers Presented at the 207th ACS National
Meeting in San Diego, California, March 13-18, 1994. American Chemical Society, Division of
Environmental Chemistry 34 (1) p 414-415.
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Permeable Chemical Reactive Barriers
Rust Geotech, Inc.
Description of Research: For about 5 years, researchers at Rust Geotech, Inc. have been conducting
laboratory batch and column studies of aquifer permeability, and two-dimensional tank and modeling
experiments on chemical reactive barriers that sorb such elements as uranium, molybdenum, copper, lead,
zinc, and radium. The primary purpose is to determine the applicability of chemical reaction barriers to in
situ remediation of uranium tailings, which threaten ground water at many DOE mill sites. Some
important areas under investigation are the sorption capacities for a variety of contaminants and the
relative immobility of the sorbing phase under aquifer flow conditions. Tests have been conducted on
barriers containing primarily low-cost materials such as hydrated lime, fly ash, barium chloride, calcium
phosphate, titanium oxide, peat, lignite, ferric oxyhydroxide, ferrous hydroxide, hydrophobic zeolite,
hydrated iron oxide, and ferrous sulfate. Extraction rates for uranium (initial concentration 30 mg/L) were
greater than 99% using hydrated lime, fly ash, barium chloride, calcium phosphate, titanium oxide, peat,
and lignite. More than 96% of the molybdenum (initial concentration 8.9 mg/L) was extracted by ferrous
sulfate, ferric oxyhydroxide, titanium oxide, peat, hematite, calcium chloride, and barium chloride. The
most extensive research effort has centered around the use of ferric oxyhydroxide to immobilize metals
and uranium. The studies have shown that ferric oxyhydroxide (1) is an inexpensive sorbent for uranium
and metals, (2) can be injected into ground water, (3) should remain immobile once emplaced, and (4)
once emplaced, should not reduce aquifer permeability. All of these issues are important to the successful
implementation of a subsurface reactive barrier.
Rust Geotech conducts its research at the Environmental Sciences Laboratory in Grand Junction,
Colorado. This lab is part of the Department of Energy's Grand Junction Project Office.
Wastes Treated: Uranium, molybdenum, arsenic, copper, lead, zinc, cadmium, chromium, and radium
Contact:
Stan J. Morrison
Rust Geotech, Inc.
Environmental Sciences Laboratory
Grand Junction Projects Office
P.O. Box 14000
Grand Junction, CO 81502
303-248-6373
References:
"Chemistry Can Contain Contamination." Groundwater Newsletter, 22, 1993.
"Industrial Materials Can Be Combined for a Barrier to Protect Groundwater at Uranium Tailings Sites."
Groundwater Newsletter. 21 (22), 1992.
Morrison, S.J. and Spangler, R.R. "Chemical Barriers for Controlling Groundwater Contamination."
Environmental Progress. 12(3), 1993, p 175.
Morrison, S.J. and Spangler, R.R. "Extraction of Uranium and Molybdenum from Aqueous Solutions: A
Survey of Industrial Materials for Use in Chemical Barriers for Uranium Mill Tailings Remediation."
Environmental Science and Technology. 26, 1992, p 1922-1931.
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Morrison, S.J.; Spongier, R.R.; Tripathi, V.S. in press. "Adsorption of Uranium (VI) on Amorphous Ferric
Oxyhydroxide at High Concentrations of Dissolved Carbon (IV) and Sulfur (VI)." Journal of
Contaminant Hydrology.
Morrison, S.J.; Tripathi, V.S.; Spangler, R.R. in press. "Coupled Reaction/Transport Modeling of a
Chemical Barrier for Controlling Uranium (VI) Contamination in Ground Water." Accepted for
publication in Journal of Contaminant Hydrology.
Zeolites as Permeable Barriers
New Mexico Institute of Mining and Technology
Description of Research: The Institute is developing a permeable barrier of altered zeolite that retains
some major classes of ground-water contaminants while allowing ground water to pass through. The
barrier is selective for major classes of soluble organics such as benzene and trichloroethylene, inorganic
cations such as lead and cadmium, and inorganic anions such as chromate and arsenate. Raw zeolite,
which has a high adsorptive capacity for positively charged contaminants, is treated with cationic
surfactants that increase its ability to adsorb organics and negatively charged inorganic contaminants. The
hydraulic properties of the surface-altered zeolite can be tailored for specific needs. Researchers are
characterizing the properties of the altered zeolite and its stability and adsorptive characteristics as a
function of environmental variables such as pH and temperature. Pilot scale tests in a permeable barrier
system, and a field demonstration are planned.
Wastes Treated: Soluble organics, inorganic cations and anions
Contact:
Robert S. Bowman
Department of Earth and Environmental Science
New Mexico Institute of Mining and Technology
Socorro,NM 87801
505-835-5992
References:
Bowman, R.S.; Flynn, M; Haggerty, G.M.; Huddleston, R.G.; Neel, D. "Organo-Zeolites for Sorption of
Nonpolar Organics, Inorganic Cations, and Inorganic Anions." Proceedings of the Joint CSCE-ASCE
National Conference on Environmental Engineering, July 12-14, 1993, Montreal, Quebec, Canada, p
1103-1109.
Bowman, R.S.; Haggerty, G.M.; Huddleston, R.G.; Neel, D.; Flynn, M. "Sorption of Nonpolar Organics,
Inorganic Cations, and Inorganic Anions by Surfactant-Modified Zeolites." In: Sabatini, D.A.; Knox,
R.C.; and Harwell, J.H. eds. Surfactant-Enhanced Remediation of Subsurface Contamination. ACS
Symposium Series 594, American Chemical Society, Washington, DC, 1995, p 54-64.
Haggerty, G.M. and Bowman, R.S. "Sorption of Inorganic Anions by Organo-Zeolites." Environmental
Science and Technology, 28, 1994, p 452-458.
Neel, D. and Bowman, R.S. "Sorption of Organics by Surface-Altered Zeolites." Proceedings 36th of the
Annual New Mexico Water Conference, November 7-8, 1991, Las Cruces, New Mexico, p 57-61.
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Sullivan, E.J.; Bowman, R.S.; Haggerty, G.M. "Sorption of Inorganic Oxyanions by Surfactant-Modified
Zeolites." Proceedings SPECTRUM '94, Nuclear and Hazardous Waste Topical Meeting, August 14-18,
1994, Atlanta, Georgia, p 940-945.
Teppen, B.J.; Hunter, D.B.; Bertsch, P.M.; Sullivan, E.J.; Bowman, R.S. "Modeling Organic Modification
of a Natural Zeolite Surface." Paper presented on August 20-24, 1995, American Chemical Society
Annual Meeting, Chicago, Illinois, 1995.
Hydrodehalogenation of Chlorinated Substances in Water
Department of Civil Engineering, Stanford University
Description of Research: Catalytic hydrodehalogenation using palladium and hydrogen is showing
promise in laboratory studies as a viable method for treating water contaminated with chlorinated
hydrocarbons even in the presence of oxygen, nitrite, sulfate, and chloride. In other laboratory scale
studies, the transformation of chlorinated organic compounds, such as tetrachloroethylene, by iron and
manganese powders in buffered water and in landfill leachate is being investigated.
Wastes Treated: TCE, PCE, other chlorinated solvents
Contact:
Martin Reinhard
Western Region Hazardous Substance Research Center
Department of Civil Engineering
Stanford University
Stanford, CA 94305-4020
415-723-0308
References:
Schreier, C.G. and Reinhard, M. "Catalytic Hydrodehalogenation of Chlorinated Ethylenes Using
Palladium and Hydrogen for the Treatment of Contaminated Water." accepted for publication in
Chemosphere, June 14, 1995.
Schreier, C.G. and Reinhard, M. "Transformation of Chlorinated Organic Compounds by Iron and
Manganese Powders in Buffered Water and in Landfill Leachate." Chemosphere, 29 (8), 1994, p 1743-
1753.
Remedial Applications of Zero-Valence Metals
Martin Marietta Energy Systems and Oak Ridge National Laboratory
Description of Research: Researchers have been conducting laboratory batch and column studies on
zero-valent iron during the past 2 years to establish the feasibility of using the metal for dechlorinating
organic solvents and removing radionuclides in situ at the Department of Energy's Paducah Gaseous
Diffusion Plant. Success in treating ground water contaminated with trichloroethene and technetium have
led to a plan to implement a year-long Superfund treatability study of ground water at the Plant.
Additional research by this group involves laboratory investigations of bimetallic processes that increase
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the dehalogenation reaction rate for TCE and improve the rate of dehalogenation of less-chlorinated
compounds, such as dichloromethane. These studies are showing success.
Wastes Treated: TCE, DCE, Vinyl Chloride, and Technetium
Contacts:
Jay L. Clausen
Martin Marietta Energy Systems
761 Veterans Avenue
Kevil, KY 42053
502-441-5090
Nic E. Korte
Environmental Sciences Division
Oak Ridge National Laboratory
Grand Junction Office, 2597 B 3/4 Rd
Grand Junction, CO 81503
303-248-6210
References:
Clausen, J.; Richards, W.L.; Korte, N.E.; Liang, L. "ORNL/MMES Research into Remedial Applications
of Zero-Valence Metals: 3) Removal of TCE, cis-l,2-DCE, Vinyl Chloride, and Technetium." Preprint
Extended Abstract. Presented before American Chemical Society, April 2-7, 1995, Anaheim, California.
Korte, N.; Muftikian, R.; Grittini, C; Fernando, Q; Clausen, J.; Liang, L. "ORNL/MMES Research into
Remedial Applications of Zero-Valence Metals: 2) Bimetallic Enhancements." Preprint Extended
Abstract. Presented before American Chemical Society, April 2-7, 1995, Anaheim, California.
Ground Water Restoration with Iron Metal
GE Corporate Research and Development
Description of Research: Researchers at GE Corporate Research and Development have been studying
the process by which iron metal and other iron-bearing minerals degrade chlorinated solvents, such as
TCE, DCE, and VC in water. This research was undertaken to gain a fundamental mechanistic
understanding of the chlorinated solvent/iron corrosion process and to determine the factors that affect
dechlorination rate and long-term performance in ground-water treatment.
Reduction of chlorinated solvents promoted by iron metal surfaces was studied in laboratory experiments
and columns with particular emphasis on reaction rates, product mass balances, ground-water treatability,
and characterization of iron metal surfaces. A we 11-instrumented pilot-scale column system was used to
predict chemical and hydraulic lifetime of commercial iron filings and to demonstrate that target effluent
concentrations could be attained. Aging effects, such as those caused by mineral precipitation and
potential biofouling, were accelerated by using flow velocities much higher than those typical of ground
waters. Researchers continue to investigate other factors that affect the design and operability of permeable
walls or columns composed of iron metal and iron minerals.
Wastes Treated: Chlorinated solvents
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Contact:
Joseph J. Salvo
GE Corporate Research & Development
1 River Road
P.O. Box 8, Bldg. Kl, 3C21
Schenectady, NY 12301-0008
518-387-6123
References:
Eykholt, G.R.; Baghel, S.S.; Sivavec, T.M.; Mackenzie, P.D.; Horney, D.P. "Conservative Flow Tracers
for Iron Column Studies." Preprint Extended Abstract. Presented at the 209th ACS National Meeting in
Anaheim, California, April 2-7, 1995. American Chemical Society, Division of Environmental Chemistry,
35(1), 1995, p 818-821.
Mackenzie, P.O.; Baghel, S.S.; Eykholt, G.R.; Horney, D.P.; Salvo, J.J.; Sivavec, T.M. "Pilot-Scale
Demonstration of Reductive Dechlorination of Chlorinated Ethenes by Iron Metal." Preprint Extended
Abstract. Presented at the 209th ACS National Meeting in Anaheim, California, April 2-7, 1995.
American Chemical Society, Division of Environmental Chemistry, 35 (1), 1995, p 796-799.
Sivavec, T.M. and Horney, D.P. "Reductive Dechlorination of Chlorinated Ethenes by Iron Metal."
Preprint Extended Abstract. Presented at the 209th ACS National Meeting in Anaheim, California, April
2-7, 1995. American Chemical Society, Division of Environmental Chemistry, 35 (1), 1995, p 695-698.
In Situ Permeable Reaction Wall
Waterloo Centre for Groundwater Research, University of Waterloo
Description of Research: Extensive bench-scale, batch and column studies over the past four years show
that zero-valent iron can enhance the degradation by abiotic reductive dechlorination of halogenated
organic compounds. The University has tested fourteen chlorinated methanes, ethanes, and ethenes using a
variety of metals. Substantial degradation rates were obtained using iron for all tested compounds except
dichloromethane. Many degradation rates were several orders of magnitude greater than those reported in
the literature for abiotic and biotic degradation. Bench-scale laboratory batch experiments and treatability
column experiments conducted with sand aquifer material confirmed halogen degradation in the presence
of iron. The success of these studies has led to the testing of above-ground and in situ applications of
permeable reaction walls for remediating contaminated ground-water and to patents.
Investigators at the University are continuing to develop various in situ barrier treatment designs for a
wide variety of common organic and inorganic ground-water contaminants including chlorinated solvents,
petroleum-derived contaminants such as BTEX, metals, nitrate, and phosphate. Several prototype systems
have been field tested, and designs for some full-scale systems have been developed.
It is expected that many of the new treatment barriers will be used with the Funnel-and-Gate™ system
developed initially at the Waterloo Centre for Groundwater Research and further developed and marketed
by Waterloo Groundwater Control Technologies, Inc. The various design options of the Funnel-and-
Gate™ are intended to direct contaminant plumes to the reactive media and direct clean water around the
plume.
Field demonstrations are planned on the following types of reactions for in situ treatment walls:
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• Promote denitrification of nitrate in a contaminant plume emanating from a septic tank by using an
organic carbon source;
• Promote biologically mediated, reductive dechlorination of selected solvents by periodic injection of a
carbon-amended solution;
• Remove iron, sulfate, and heavy metals in ground water from mine tailings using chemically active
organic carbon to promote sulfate reduction;
• Remove phosphate by precipitation using a permeable iron oxyhydroxide solid; and
• Remove electroactive metals, such as hexavalent chromium, using zero-valent iron.
The Waterloo Centre for Ground-water Research is part of Ontario's Centres of Excellence program, a
government sponsored partnership with academia and industry.
Wastes Treated: Numerous organic compounds such as carbon tetrachloride, chloroform, TCE, PCE, and
BTEX; as well as metals, nitrate, and phosphate
Contact:
Stephanie O'Hannesin
Waterloo Centre for Groundwater Research
University of Waterloo
Waterloo, Ontario N2L 3G1 Canada
519-885-1211
References:
Blowes, D.W. and Ptacek, C.J. "Geochemical Remediation of Ground Water by Permeable Reactive
Walls: Removal of Chromate by Reaction with Iron-Bearing Solids." Proceedings of the Subsurface
Restoration Conference, 3rd International Conference on Ground Water Quality Research, June 21-24,
1992, Dallas, Texas, p 214-216.
Devlin, J.F. and Barker, J.F. "A Semipassive Nutrient Injection Scheme for Enhanced In Situ
Bioremediation." Ground Water, 32 (3), 1994, p 374.
Gillham, R.W. and O'Hannesin, S.F. "Metal Catalyzed Abiotic Degradation of Halogenated Organic
Compounds." Ground Water 29 (5), 1991, p 752.
Gillham, R.W. and Burris, D.R. "In Situ Treatment Walls—Chemical Dehalogenation, Denitrification, and
Bioaugmentation." Proceedings from the Subsurface Restoration Conference, Dallas, Texas, June 21-24
1992. Houston: Rice University, Department of Environmental Science and Engineering, p 66-68.
Gillham, R.W.; O'Hannesin, S.F.; Orth, W. Scott. "Metal Enhanced Abiotic Degradation of Halogenated
Aliphatics: Laboratory Tests and Field Trials." Paper presented on March 9-11, 1993, HazMat Central
Conference, Chicago, Illinois, 1993.
Smyth, D.J.A.; Cherry, J.A.; Jowett, R.J. "Funnel-and-Gate for In Situ Groundwater Plume Containment."
Presented at Superfund XV, Washington, DC, November 28-December 1, 1994.
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Permeable Reactive Barriers
Los Alamos National Laboratory
Description of Research: Researchers have evaluated the applicability of gel materials in barriers to
enhance natural biologic communities and to test chemical tracers and remote monitoring of hydrologic
systems. Investigators have used zeolite, silica gel, sand, bentonite, aluminum crosslink polyacrylamide,
and peat in permeable barriers. Approaches to managing biologic communities on the margins of a site in
combination with other barrier systems are being evaluated. Barriers used as part of post-closure
monitoring systems serve to warn of impending contaminant migration.
Post-closure monitoring experiments will focus on the evaluation of water saturation and chemical
transport using tracers such as common anions, soluble organic acids, semivolatile organic acids,
fluorescein, chromium, EDTA, and toluene labeled with carbon-13 for the bio-barrier.
The first barrier and monitoring systems were installed in 1992. Field tracer tests were scheduled for
completion in early 1994, however, Department of Energy funding was discontinued after the first year.
The research was conducted in partnership with the Universities of Houston and New Mexico and the
DuPont and Pfizer Chemical Companies.
Contact:
Ken Bostick or Dave Janecky
Los Alamos National Laboratory
Mail Stop J495, Organization EES-15
Los Alamos, NM 87545
505-667-8483 (Bostick) or 505-665-0253 (Janecky)
References:
DOE-AL. Technology Information Profile (Rev.2), Technical Name: Barriers and Post-Closure
Monitoring. DOE ProTech Database, TTP Reference Number: AL-1211-25, February 26, 1993.
Hansen, W.; Bostick, K.; Janecky, D. Barriers and Post-Closure Monitoring. Briefing Chart, Los Alamos
National Laboratory, Los Alamos, NM. TTP Reference Number AL-1212-25, October 10 1992.
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General References
"Canada Pushes Innovative Remediation Technology: Permeable Reaction Wall Used for In Situ
Degradation of Halogenated Organic Compounds." Chemical Engineering Progress, June 1993, p 14.
Gillham, R.W.; Blowes, D.W.; Ptacek, C.J.; O'Hannesin, S.F. "Use of Zero-Valent Metals for In Situ
Remediation of Contaminated Ground Water." In: Proceedings of the 3 3rd Hanford Symposium on Health
and the Environment—In Situ Remediation: Scientific Basis for Current and Future Technologies. Pasco,
Washington. November 11, 1994. Columbus, Ohio: Battelle Press, 1994.
Gillham, R.W. and O'Hannesin, S.F. "Enhanced Degradation of Halogenated Aliphatics by Zero-Valent
Iron." Ground Water, 32 (6), 1994, p 958-967.
Henderson, T. "Geochemical Reduction of Hexavalent Chromium in the Trinity Sand Aquifer." Ground
Water, 32 (3), May-June 1994, p 477-486.
McCalady, Donald (ed). "Chemical Mediation of Pollutant Transport in Aqueous Systems." Journal of
Contaminant Hydrology, 9 (1-2), January 1992.
"Metal-Enhanced Reductive Dehalogenation (MERD), a Simple, Passive Technology for Reductive
Dehalogenation of Organics" Environmental Science and Technology, June 1994, p 254.
Starr, R.C. and Cherry, J.A. "Funnel-and-Gate System Directs Plumes to In Situ Treatment." Ground
Water Currents, EPA/542/N-93/006, June 1993.
Starr, R.C. and Cherry, J.A. "In Situ Remediation of Contaminated Groundwater: The Funnel-and-Gate
System." Ground Water, 32 (3), 1994, p 46.
Taylor, R.T.; Durham, W.B.; Duba, A.G.; Jackson, K.J.; Knapp, R.B.; Knezovich, J.P.; Wijesinghe, A.M.;
Bishop, D.J.; Hanna, M.L.; Jovanovich, M.C.; Shannard, D.R. "In Situ Microbial Filters."Proceedings of
In Situ Bioremediation Symposium '92, Niagara-on-the-Lake, Ontario, Canada, September 20-24, 1992.
Burlington, Ontario Canada: Wastewater Technology Centre, p 66-67.
Waterloo Center for Groundwater Research. Groundwater Notes. 7 (1), 1994, p 1-12. Published by
Waterloo Centre for Groundwater Research, University of Waterloo, Waterloo, Ontario N2L 3G1 Canada.
Zotter, K. and Licsko, I. "Removal of Chromium (VI) and Other Heavy Metals from Groundwaters in
Neutral and Alkaline Media." Water Science and Technology, 26 (1-2), 1992, p 207-216.
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