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Permeable Reactive Barriers, Permeable Treatment Zones, and Application of Zero-Valent Iron

Application

Application of Zero-Valent Iron

Cost and Performance Report: Nanoscale Zero-Valent Iron Technologies for Source Remediation
A. Gavaskar, L. Tatar, and W. Condit
Environmental Security Technology Certification Program, CR-05-007-ENV, 54 pp, 2005.

USA Defense Depot Memphis
U.S. EPA Region 4 Web site.

The most consistently detected VOC group of chemicals at concentrations above comparison criteria in the site media are CVOCs, such as TCE, PCE, 1,1,2,2-PCA, carbon tetrachloride, and chloroform. The final ROD (2004) for Dunn Field calls for excavation and off-site disposal of the contents of pits and burial trenches, SVE of principal-threat waste in the unsaturated subsurface soils, treatment of the groundwater CVOCs via injection of ZVI, and installation of a ZVI PRB to address high groundwater concentrations downgradient of Dunn Field. SVE operation began in the VOC-contaminated sand and gravel layer beneath source areas in July 2007. In situ thermal desorption (ISTD) began in the VOC-contaminated silty clay zone (top 30 ft) in May 2008. VOC removals for all remedies to date (soil and groundwater) totals ~9,000 pounds. A revised proposed plan and ROD amendment are planned for 2009 to document changes undertaken to achieve the remedial action objectives of the original ROD.

Permeable Reactive Barriers

Cost and Performance Case Studies from the Federal Remediation Technologies Roundtable

An Assessment of Zero Valence Iron Permeable Reactive Barrier Projects in California
J. Muegge, California Department of Toxic Substances Control, Document 1219, 154 pp, 2008

A review of the performance of 10 PRBs installed primarily to address chlorinated contaminants indicates that a ZVI PRB should not be expected to provide near-term improvement of water quality very far below its installation. The same levels observed downgradient of a PRB before its installation can persist for extended periods (often decades) despite the presence of a PRB. The PRBs were installed at Alameda Naval Air Station, BP-Hitco, DuPont Oakley, Fairchild/Applied Materials, Intersil, Moffett Field, Mohawk Laboratory, Sierra Army Depot (2 separate PRBs), and Travis Air Force Base. Additional information: This report is summarized by J.P. Muegge and P.W. Hadley in a paper in Remediation Journal 20(1):41-57(2009).

Capstone Report on the Application, Monitoring, and Performance of Permeable Reactive Barriers for Ground-Water Remediation, Volume 1: Performance Evaluations at Two Sites
2003. R.T. Wilkin and R.W. Puls, U.S. EPA, National Risk Management Research Lab., Ada, OK. EPA 600-R-03-045a, 156 pp.

Capstone Report on the Application, Monitoring, and Performance of Permeable Reactive Barriers for Ground-Water Remediation, Volume 2: Long-Term Monitoring of PRBs � Soil and Ground Water Sampling
2003. C.J. Paul; M.S. McNeil; F.P. Beck, Jr.; P.J. Clark; R.T. Wilkin; R.W. Puls. EPA 600-R-03-045b, 145 pp.

DNAPL Remediation: Selected Projects Where Regulatory Closure Goals Have Been Achieved
EPA 542-R-09-008, 2009

The purpose of this paper is to highlight sites where dense nonaqueous phase liquid (DNAPL) source reduction has been demonstrated as an aid in meeting regulatory cleanup goals. The presence of DNAPL in the subsurface can serve as a long-term source of dissolved contaminant plumes in groundwater, making it more difficult to reach regulatory closure. However, once the DNAPL source is addressed, residual groundwater plumes may be more amenable to treatment, including less aggressive techniques such as monitored natural attenuation (MNA) or bioremediation. This paper updates the document, DNAPL Remediation: Selected Projects Approaching Regulatory Closure, prepared in 2004 by providing more recent information on technologies and on five additional selected sites at which DNAPL source reduction technologies were applied.

Demonstration of a Multifunctional Permeable Reactive Barrier for the Treatment of Landfill Leachate Contamination
T. Van Nooten, H. Sterckx, W. Boenne, L. Bastiaens, D. Dirickx, and P. Verkaeren.
In Situ and On-Site Bioremediation 2009: Proceedings of the 10th International In Situ and On-Site Bioremediation Symposium, 5-8 May, Baltimore, Maryland. Battelle Press, ISBN: 9780981973012, 2009

A pilot-scale multifunctional PRB (multibarrier) was designed and demonstrated at the Belgian landfill site Hooge Maey for semipassive treatment of landfill leachate containing ammonium and adsorbable organic halogens (AOX). The pilot-scale implementation employed a steel container 9 m in length containing different treatment compartments. AOX and COD were removed efficiently in a compartment filled with active carbon. Nitrification compartments equipped with diffusive oxygen emitters were present to effect microbial conversion of ammonium to nitrite, which in turn was converted to N2 in a downgradient denitrification compartment supplied with an external carbon source. Despite an efficient diffusive oxygen supply, ammonium removal in the nitrification compartments was low due to exceptionally cold winter temperatures that inhibited microbial activity. Nitrification and denitrification processes are expected to improve with increasing temperatures in spring. Remaining ammonium concentrations were removed mainly by ion exchange in a compartment filled with clinoptilolite until the material reached saturation. Potential in situ bioregeneration of the saturated clinoptilolite is being investigated. The multibarrier project has its own Web site with a project bibliography.

Design, Construction and Monitoring of a Permeable Reactive Barrier Technology for Use at Rocky Flats Environmental Technology Site (RFETS)
2000. Dwyer, Brian P., Sandia National Labs., Albuquerque, NM, Report No: SAND2000-2702. NTIS: DE00767720. 65 pp.

Design, Construction, and Monitoring of the Permeable Reactive Barrier in Area 5 at Dover Air Force Base
2000. Gavaskar, Arun; Neeraj Gupta; Bruce Sass; Woong-Sang Yoon; Robert Janosy, Battelle, Columbus, OH. Report No: AFRL-ML-WP-TR-2000-4546. NTIS: ADA380005. 399 pp.

Enhancements to Natural Attenuation: Selected Case Studies
T.O. Early (ed.).
WSRC-STI-2007-00250, 132 pp, 2007

Presents case studies of engineered covers; biostimulation and bioaugmentation to address trichloroethene (TCE) contamination at Cape Canaveral, FL; a ZVI PRB for TCE and chromate at the U.S. Coast Guard Support Center, Elizabeth City, NC; a full-scale mulch biowall for TCE at Offutt Air Force Base, NE; and a wetland enhancement/reactive mat for TCE, carbon tetrachloride, chloroform, and 1,1,2,2-tetrachloroethane at Aberdeen Proving Ground.

Evaluation of Permeable Reactive Barrier Performance
EPA 542-R-04-004, 2004

This report on the performance of permeable reactive barriers (PRB) for groundwater remediation was prepared under the auspices of the Federal Remediation Technologies Roundtable, a collaborative effort among federal agencies involved in hazardous waste site cleanup. Three United States (U.S.) government agencies, the Department of Defense (DoD), Department of Energy (DOE), and United States Environmental Protection Agency (EPA), as well as the Interstate Technologies and Regulatory Council (ITRC) contributed to the report, which is a concise summary of the conclusions and recommendations of the three agencies' individual studies at different sites.

Field Applications of In Situ Remediation Technologies: Permeable Reactive Barriers
2002

This document summarizes technical data and lessons learned from profiles of more than 40 installations of permeable reactive barriers (PRBs) for ground-water remediation in the United States, Canada, and selected locations abroad. Included are data from ongoing and completed pilot- and full-scale PRB demonstrations and full-scale cleanups. More in-depth information about each of the sites included in this summary document is available on the RTDF web site.

Fry Canyon, UT, USGS Project Home Page

Three different PRBs were installed at the demonstration site in 1997, respectively containing Cercona Bone Char Phosphate, Cercona foamed ZVI pellets, and amorphous ferric oxide. The project will utilize geochemical and hydrologic approaches to assess the performance of the PRBs toward the long-term remediation of the Fry Canyon upgrade tailings site.

Field Demonstration of Permeable Reactive Barriers to Remove Dissolved Uranium from Groundwater, Fry Canyon, Utah, September 1997 through September 1998: Interim Report
Selected Hydrologic Data for the Field Demonstration of Three Permeable Reactive Barriers near Fry Canyon, Utah, 1996-2000

Handbook of Groundwater Remediation Using Permeable Reactive Barriers: Applications to Radionuclides, Trace Metals, and Nutrients
2002. David Naftz, et al. (eds.). Academic Press, San Diego, CA. ISBN: 0125135637, 550 pp.

This handbook offers numerous case studies to introduce the reader to current applications, innovations, and methods for using PRBs in the removal of inorganic contaminants from ground water.

In Situ Chemical Reduction (ISCR) Technologies: Significance of Low eH Reactions
J. Dolfing, M. Van Eekert, A. Seech, J. Vogan, and J. Muellers.
Soil & Sediment Contamination, Vol 17 No 1, p 63-74, Jan 2008

In March 2005, 22,000 kg of ISCR reagent was injected to form an 82-m PRB across a plume of dissolved-phase carbon tetrachloride (CT) about 150 m downgradient of the suspected source area. The ISCR reagent slurry was injected at 126 injection points advanced via direct push. By August 2006, CT concentrations had decreased from > 1,600 ppb to < 5 ppb, achieving > 99% removal.

An In Situ Permeable Reactive Barrier for the Treatment of Hexavalent Chromium and Trichloroethylene in Ground Water
D.W. Blowes, et al.
EPA 600-R-99-095a, EPA 600-R-99-095b, and EPA 600-R-99-095c, 1999.

In Situ Remediation Technology Status Report: Research and Application of Permeable Barriers
1998

This document is an attempt to compile worldwide research efforts and applications in the field of permeable reactive barriers (PRB). Research projects are organized by the type of contamination treated (organics or inorganics) and by the type of reaction process (sorption, precipitation, substitution, or degradation), and then by the specific material. Field projects are organized by state, province, or country.

In Situ Remediation Technology Status Report: Treatment Walls
EPA 542-K-94-004, 1994

Describes field demonstrations or full-scale applications of in situ abiotic technologies for nonaqueous phase liquids and ground water treatment.

Innovative Technology Evaluation Report: EnviroMetal Technologies, Inc., Metal-Enhanced Dechlorination of Volatile Organic Compounds Using an In-Situ Reactive Iron Wall
EPA 540-R-98-501, 1998. 110 pp.

Long-Term Groundwater Monitoring Optimization, Clare Water Supply Superfund Site, Permeable Reactive Barrier and Soil Remedy Areas, Clare, Michigan
EPA 542-R-07-010, 2007

This report contains a review of the long-term groundwater monitoring network for the Permeable Reactive Barrier (PRB) and Soil Remedy Areas at the Clare Water Supply Superfund Site in Clare, Michigan. The current monitoring network in each area was evaluated using a formal qualitative approach and statistical tools found in the Monitoring and Remediation Optimization System software (MAROS). The report also contains recommendations for the groundwater monitoring networks based the results of these qualitative and quantitative evaluations.

Long-Term Performance Assessment of a Permeable Reactive Barrier at Former Naval Air Station Moffett Field
A. Gavaskar, W.S. Yoon, J. Sminchak, B. Sass, N. Gupta, J. Hicks, and V. Lal.
Naval Facilities Engineering Service Center, Port Hueneme, CA. CR-05-006-ENV, 37 pp, 2005.

A pilot-scale PRB filled with zero-valent iron was installed at former Naval Air Station Moffett Field in April 1996 to address chlorinated organics in the ground water. It was monitored periodically for the next 8 years. This report describes the results of the last round of monitoring conducted in July 2004, the relationship of the recent results to those of previous rounds, and implications for the longevity and hydraulic performance of the PRB.

Long-Term Performance of Permeable Reactive Barriers Using Zero-Valent Iron: An Evaluation at Two Sites. Environmental Research Brief
2002. R.T. Wilkin, R.W. Puls, G.W. Sewell, U.S. EPA, Ada, OK. EPA 600-S-02-001, 19 pp.

Mine Waste Technology Program: Permeable Treatment Wall Effectiveness Monitoring Project, Nevada Stewart Mine
A.L. McCloskey.
EPA 600-R-06-153, 100 pp (plus appendices A-F, 282 pp), 2007

This project demonstrates the effectiveness of Apatite II™ (cleaned fishbone) to remove metals (zinc, iron, manganese, lead, and cadmium) from water flowing from a mining site.

Passive Reactive Barrier. Innovative Technology Summary Report
2002. U.S. DOE, Office of Environmental Management. DOE/EM-0623, 37 pp.

This report describes the performance of two PRBs installed at DOE's Oak Ridge Reservation in Tennessee.

Performance Assessment and Recommendations for Rejuvenation of a Permeable Reactive Barrier: Cotter Corporation's Canyon City, Colorado, Uranium Mill
DOE-LM/GJ816-2005, ESL-RPT-2005-02, 130 pp, 2005

A ZVI PRB was installed in 2000 to treat molybdenum and uranium at the currently operating Cotter Corporation mill site. Though the barrier eventually failed for Mo, U concentrations remained at less than 0.006 mg/L. The ZVI became clogged by mineral precipitants, and modifications (e.g., a pretreatment zone composed of coarse gravel and ZVI) were suggested. Given the conditions experienced at the PRB in 2003, Cotter evaluated the system at years' end and subsequently initiated pumping of upgradient groundwater to the site's primary impoundment.

Permeable Reactive Barrier Facility at the Bodo Canyon Disposal Cell, Durango, Colorado
U.S. DOE, Office of Legacy Management, Grand Junction, CO.

A PRB facility was constructed at the Durango, Colorado, Disposal Site in 1995 to test PRB designs for passive remediation of uranium-contaminated groundwater via treatment of contaminated tailings water (leachate) issuing from a seep into a subsurface engineered collection gallery and drained by gravity to a lined retention basin for treatment at the site's downgradient boundary. Several PRBs (ZVI, copper wool, and steel wool) were used to treat As, Mo, Se, U, V, and Zn. The ZVI barrier operated from August 1999 until June 2004, when flow ceased from the seep and remediation was no longer needed. It maintained effluent uranium concentrations of less than 0.01 mg/L, and was highly effective in treating contaminants.

Permeable Reactive Barrier at the Monticello Mill Tailings Site, Monticello, Utah
U.S. DOE, Office of Legacy Management, Grand Junction, CO.

In 1999, DOE installed a ZVI-containing PRB downgradient of the former uranium milling site at Monticello, UT. The PRB has been effective in reducing concentrations of As, Se, U, and V to nondetectable levels on the PRB's downgradient side, and Mo and nitrate to near nondetect. Soil-bentonite slurry walls direct groundwater to the PRB, but some contaminated groundwater is flowing around the south slurry wall. Methods that might be used to mend the gap on the south end of the slurry wall were investigated. There has been some evidence of barrier clogging, and chemical flushing of the barrier to remedy the clogging was investigated. In 2005, a supplemental treatment cell containing a mixture of ZVI and gravel was installed at the site. The project has generated the following reports:

Permeable Reactive Barriers Projects Page

Permeable Reactive Barriers for Inorganic and Radionuclide Contamination
2005

This document was prepared by Kate Bronstein, a National Network of Environmental Management studies grantee, under a fellowship from the U.S. Environmental Protection Agency. This paper is meant to be an updated reference for project managers, engineers, students, and others interested in a review of case studies of the instances where permeable reactive barriers have been used to remediate sites contaminated with inorganics and radionuclides. This paper mainly focuses on case studies, but a brief overview is given on topics such as: treatment media types, reactive processes, site characterization, configuration, and the nature of contamination.

Permeable Reactive Wall Remediation of Chlorinated Hydrocarbons in Groundwater: ESTCP Cost and Performance Report (CU-9604)
1999, ESTCP

Remediation of TNT and RDX in Groundwater Using Zero-Valent Iron Permeable Reactive Barriers: Cost and Performance Report
ESTCP, Project ER-0223, 66 pp, 2008

A mixed iron/sand PRB was installed to remove TNT and RDX contamination from groundwater at the Cornhusker Army Ammunition Plant near Grand Island, Nebraska. Performance was evaluated over a 20-month period. Installation costs for the pilot-scale barrier (50 ft long by 15 ft deep by 3 ft thick) were $138,000, ~$180 per square ft.

Report for Full-Scale Mulch Wall Treatment of Chlorinated Hydrocarbon-Impacted Groundwater
2004. Groundwater Services, Inc., Houston, TX. DTIC: ADA422621, 97 pp.

Treatment of RDX & HMX Plumes Using Mulch Biowalls
C. Newell. ESTCP Project ER-0426, 77 pp, 2008

The field demonstration conducted at the Pueblo Chemical Depot in Colorado represents the first ever application of mulch PRBs for the treatment of explosives contamination in groundwater. The state-mandated, site-specific cleanup criteria of 0.55 ppb RDX and 602 ppb HMX was used as the project goal. A pilot-scale organic mulch/pea gravel biowall 100 ft long and 2 ft thick was installed using one-pass trenching. The PRB was in place by November 16, 2005, and all performance objectives were met by June 2006, when the system appeared to have reached a pseudo steady state. See also the ESTCP Cost and Performance Report

The Trench and Gate Groundwater Remediation System
1997. Marc W. Bowles, Master's thesis, University of Calgary, 250 pp.

The trench-and-gate PRB is a modified funnel-and-gate system suitable for installation in tills. Modifications include the addition of high hydraulic conductivity trenches along the upgradient side of the funnel walls and a reinfiltration gallery down-gradient of the treatment gate. Preferential groundwater flow through the added high permeability infrastructure prevents mounding and induces a capture zone both horizontally, and vertically larger than the cross-sectional funnel area. Coupled with bioremediation catalyzed by biosparging, or other remediation technologies, the system constitutes an economical, long-term, in situ method for contaminant plume capture and treatment, suitable for low to moderate permeability sediments. A prototype trench and gate was successfully installed at the East Garrington Gas Plant, Alberta, Canada.

Permeable Treatment Zones

Cost and Performance Case Studies from the Federal Remediation Technologies Roundtable

The Ashumet Pond Reactive Barrier
Massachusetts Military Reservation, Cape Cod.

A geochemical barrier was applied in the groundwater discharge zone of a kettle-hole pond to address the well-defined discharge of a dissolved phosphorus plume. In August 2004, ZVI was mixed into near-shore pond-bottom sediment (3% by weight) to a depth of about 0.6 m, extending 12.2 m offshore along 91.4 m of shoreline in the area of highest observed pond-bottom phosphorus. The sediment mixture was created by excavating the pond-bottom material while the pond was locally dewatered using a cofferdam and large pumps. An excavator mixing bucket blended the pond-bottom sediment and iron filings prior to placement of the mixture on the pond bottom. The ZVI barrier is ~300 ft long, 40 ft wide, and 3 ft thick. Excavation of the dewatered pond bottom provided a unique opportunity to install instrumentation for barrier performance monitoring. Monitoring the performance of a remediation system at this interface required adapting sampling strategies similar to those used in groundwater/surface-water interaction studies. Additional information: McCobb et al. 2009a, McCobb et al. 2009b

Attenuated Anaerobic Dechlorination of Groundwater Using HRC�. Mactec - Harding ESE: Demonstration Bulletin
U.S. EPA, Risk Management Research Laboratory, Cincinnati, OH.
EPA 540-R-08-003, 2 pp, 2008

An in situ PRB was designed that utilizes Hydrogen Release Compound (HRC�) to treat ground water contaminated with chlorinated compounds. A demonstration of this technology was conducted in 2000 near the Fisherville Mill brownfields site in South Grafton, MA, to determine its effectiveness in eliminating TCE and daughter products from the ground water. The cleanup criteria were not achieved at the downgradient monitoring wells over a period of 2 years despite extensive conversion of TCE to DCE.

Demonstration of In Situ Dehalogenation of DNAPL Through Injection of Emulsified Zero-Valent Iron at Launch Complex 34 in Cape Canaveral Air Force Station, Florida: Innovative Technology Evaluation Report
A. Gavaskar, W.-S. Yoon, M. Gaberell, E. Drescher, L. Cumming, J. Sminchak, J. Hicks, B. Buxton, M. Morara, T. Wilk, and L. Bahn.
EPA 540-R-07-006, 223 pp, 2004

The field demonstration of emulsified zero-valent iron (EZVI) technology for treatment of a TCE DNAPL source zone began at Launch Complex 34 in June 2002 and ended in January 2003. Long-term ground-water monitoring results collected in December 2003 and March 2004 indicate that the EZVI treatment had a long-lasting effect on the chlorinated contaminants in the subsurface. TCE, cis-1,2-DCE, and (eventually) VC levels declined sharply in the one year following EZVI injection, and ethene levels increased substantially.

Demonstration/Validation of Electrolytic Reactive Barriers for Treatment of Energetic Compounds in Groundwater at the Pueblo Chemical Depot (ESTCP ER-0519)
D Gilbert, T. Sale, and M. Petersen.
SERDP/ESTCP Partners in Environmental Technology Technical Symposium & Workshop, 2008

An e-barrier was installed at the Pueblo Chemical Depot (Pueblo, CO) to intercept groundwater affected by explosives constituents. The demonstration e-barrier consists of 15 individual panels of expanded titanium/mixed metal oxide mesh electrodes mounted to vinyl sheet pile. Power is supplied to the electrodes by a 2 kW solar power supply. Contaminated groundwater flowing through the e-barrier is subjected to two sequences of electrolytic oxidation/reduction for degrading the dissolved explosives and intermediates. At the current voltage setting (6.2 V), the system uses ~500 W total power. Performance monitoring will continue through fall 2008. July 2009 Update

Development of Permeable Reactive Barriers (PRB) Using Edible Oils
R.C. Borden.
SERDP Project ER-1205, 159 pp, 2008

A detailed field pilot test was conducted to evaluate the use of an emulsified oil biobarrier to enhance the in situ anaerobic biodegradation of perchlorate and chlorinated solvents in groundwater. The biobarrier was installed by injecting 380 L of commercially available soybean oil-in-water emulsion through 10 direct-push injection wells over a 2-day period. Field monitoring results over a 2.5 year period following emulsion injection indicates the oil injection generated strongly reducing conditions in the oil-treated zone with depletion of dissolved oxygen, nitrate, and sulfate, and increases in dissolved iron, manganese, and methane. Perchlorate at 3,100 to 20,000 µg/L was degraded to below detection (<4 µg/L) in the injection and nearby monitor wells within 5 days of injection. Two years after the single emulsion injection, perchlorate was less than 6 µg/L in every downgradient well compared to an average upgradient concentration of 13,100 µg/L. Emulsion injection stimulated reductive dechlorination of 1,1,1-TCA, PCE, and TCE during groundwater migration through the biobarrier but did not reduce them to target treatment levels.

Edible Oil Barriers for Treatment of Chlorinated Solvent Contaminated Groundwater
M.T. Lieberman and R.C. Borden.
ESTCP Project ER-0221, 228 pp, 2009

A pilot test was conducted between 2003 and 2007 at Charleston Naval Weapons Station, SC, to evaluate the effectiveness of EOS®, a commercially available emulsified oil substrate, for enhancing the biodegradation of dissolved-phase chlorinated VOCs in groundwater and aquifer material in a treatment cell. The cell contained 4,000 cubic ft of contaminated aquifer material with up to 16,000 µg/kg TCE in soil and >20,000 µg/L TCE in groundwater. Phase I involved site characterization, baseline sampling, EOS injection, and monitoring for 28 months. Phase II involved a bench-scale treatability study, development and injection of a newly formulated pH-buffered substrate to overcome a pH problem, and an additional 11 months of monitoring to measure the effect of the second substrate. The buffered EOS raised the pH and alkalinity of the aquifer, which allowed the native dehalorespiring populations to re-initiate their metabolism of TCE and DCE and biodegrade TCE throughout the test cell. Over the entire 41-month monitoring period in Phases I and II, the total chlorinated VOC concentration decreased from 198 µM to 17 µM, a decline of 91%.

Edible Oil Barriers for Treatment of Perchlorate Contaminated Groundwater
2005

This final technical report documents the demonstration of emulsified edible oil barriers for groundwater remediation at a confidential perchlorate site in Maryland. The general purpose of the demonstration was to evaluate the efficacy of emulsified oils for treating perchlorate contaminated groundwater. A second demonstration was performed as part of this project to evaluate the use of emulsified oils for remediation of chlorinated solvent impacted groundwater at the Charleston Naval Weapons Station (NWS) in South Carolina. The work at the Charleston NWS is still ongoing and will be reported separately. In addition, a technical protocol document is being written under this demonstration project which describes in detail the use of emulsified oils for enhanced anaerobic bioremediation of perchlorate and chlorinated solvents. See also the Technical Report Addendum (2008)

Electrically Induced Redox Barriers for Treatment of Groundwater
T. Sale, M. Petersen, and D. Gilbert.
Environmental Security Technology Certification Program (ESTCP), CU-0112, NTIS: ADA438421, 187 pp, 2005

Closely spaced permeable electrodes can be installed through a ground-water contaminant plume in the format of a permeable reactive barrier, called an e-barrier. An e-barrier was installed at F.E. Warren Air Force Base in August 2002 in the path of a shallow alluvial TCE plume. This report documents results from a three-year collaboration between ESTCP and Colorado State University on the development and testing of this innovative electrolytic approach for managing redox-sensitive contaminants in ground water. According to the Final Report Addendum (2008), the initial project was completed in March 2005, and two additional studies were conducted: screening of titanium-mixed metal oxide electrodes for e-barriers (2003-2005) and extended operation of the e-barrier field demonstration for TCE remediation at F.E. Warren AFB (2004-2006).

FY2003 Annual Summary Report for the In Situ Redox Manipulation Operations
R.F. Raidl and G.G. Kelty.
DOE/RL-2004-06, OSTI: DE00825446, 85 pp, May 2004

This progress and performance report discusses the in situ redox manipulation (ISRM) interim remedial action at the Hanford 100-HR-3 Operable Unit to address the hexavalent chromium plume in the southwest portion of the 100-D Area. Implementation of the ISRM technology involves creating a permeable subsurface treatment zone by injecting sodium dithionite into the aquifer, which creates a chemically reduced environment. Hexavalent chromium passing through the treatment zone is reduced to less toxic and less mobile trivalent chromium.

Field Application of a Permeable Reactive Barrier for Treatment of Arsenic in Ground Water
R.T. Wilkin, S.D. Acree, D.G. Beak, R.R. Ross, T.R. Lee, and C.J. Paul.
EPA 600-R-08-093, 81 pp, 2008

In June 2005, a pilot-scale PRB containing granular iron was installed at a former metal smelting facility near Helena, MT, to treat ground water contaminated with concentrations (>25 mg/L) of arsenite and arsenate. The barrier is 9.1 m long, 14 m deep, and 1.8 to 2.4 m wide (in the direction of ground-water flow). Within the PRB, As concentrations are 2 to <0.01 mg/L. After 2 years of operation, significant decreases in As concentrations are evident. This report covers site characterization, remedial design and implementation, and monitoring results for this pilot-scale PRB.

In Situ Bioremediation of MTBE in Groundwater
P. Johnson, C. Bruce, and K. Miller.
TR-2222-ENV, 118 pp, 2003

A biologically reactive ground-water flow-through barrier (a 'biobarrier') was established at the Naval Base Ventura County, Port Hueneme, CA, to prevent further contamination of ground water by MTBE leaching from gasoline-contaminated soils. The biobarrier was installed downgradient of a gasoline-spill source zone. Ground water containing dissolved MTBE flowed to and through the biobarrier, and the microorganisms in the treatment zone converted MTBE to carbon dioxide and water. Gas injection wells were installed to introduce oxygen into the treatment zone.

In Situ Chemical Reduction of Cr(VI) in Groundwater Using a Combination of Ferrous Sulfate and Sodium Dithionite: A Field Investigation
R.D. Ludwig, C. Su, T.R. Lee, R.T. Wilkin, S.D. Acree, R.R. Ross, and A. Keeley.
Environmental Science & Technology, Vol 41 No 15, p 5299-5305, 2007

A field study was conducted to evaluate the performance of an in situ redox zone for the treatment of a dissolved-phase hexavalent chromium (Cr[VI]) plume at a former industrial site. The in situ redox zone was created by injecting a blend of 0.2M ferrous sulfate and 0.2M sodium dithionite into the path of the plume within a shallow, unconfined aquifer formation of medium-to-fine sand. Monitoring data collected over a period of 1,020 days after more than 100 m of linear ground-water flow through the treatment zone indicated sustained treatment of dissolved-phase Cr(VI) from initial concentrations between 4 and 8 mg/L to less than 0.015 mg/L.

In Situ Reactive Zones (IRZ) Data Sheet
U.S. Navy, Naval Facilities Engineering Command, Environmental Restoration Technology Transfer, Multimedia Training Tools website, 16 pp, 2005.

In Situ Redox Manipulation Permeable Reactive Barrier Emplacement: Final Report, Frontier Hard Chrome Superfund Site, Vancouver, WA
V.R. Vermeul, M.L. Rockhold, B.N. Bjornstad, J.E. Szecsody, C.J. Murray, M.D. Williams, D.R. Newcomer, and Y. Xie.
PNWD-3361, 107 pp + separate appendices, 2004

This report documents results from the emplacement of an in situ redox manipulation (ISRM) treatment zone for the remediation of chromate-contaminated ground water. Additional information: Groundwater Monitoring Network Optimization (2007); 5-Year Review (2008).

Nease Chemical Site, Columbiana County, Ohio - Technology Update #2: Nanotechnology
U.S. EPA Region 5, 2 pp, June 2007

A field study was conducted at the site in November 2006 to confirm the effectiveness of injecting nanoscale zero-valent iron (NZVI) to treat highly contaminated ground water in fractured sedimentary bedrock and to support the design of the full-scale treatment approach. One hundred kg of NZVI in 2,665 gallons of clean water were injected into a highly contaminated portion of the aquifer. The iron was injected in batches containing powdered soy as an organic dispersant, and most batches contained a small amount of palladium. Substantial reductions of PCE (38 to 88% of initial concentrations) and TCE (30 to 70%) were noted in all wells.

Remediation of Explosives in Groundwater Using Zero-Valent Iron In Situ Treatment Wells
R. Johnson and P. Tratnyek.
ESTCP, Project ER-0223, 48 pp, 2008

This report describes the advantages and limitations of a treatment approach for explosives contamination in groundwater tested at Cornhusker Army Ammunition Plant. Granular iron was placed outside of the screens in a pair of dual-screened wells and groundwater circulation was promoted between the wells. Water circulated between the two treatment wells relatively quickly, and explosives concentrations decreased. The cost of each of the two wells was approximately $40,000.

Additional Information Bibliography

McCobb, T.D., D.R. LeBlanc, and A.J. Massey. 2009a. Monitoring the removal of phosphate from ground water discharging through a pond-bottom permeable reactive barrier. Ground Water Monitoring and Remediation 29(2):43-55.

McCobb, T.D., D.R. LeBlanc, L.A. Parsons, and J.G. Blount. 2009b. Distribution of Treated-Wastewater Constituents in Pore Water at a Pond-Bottom Reactive Barrier, Cape Cod, Massachusetts. USGS Scientific Investigations Map 3078, 1 sheet.

U.S. EPA Contaminated Site Cleanup Information (CLU-IN)

Permeable Reactive Barriers, Permeable Treatment Zones, and Application of Zero-Valent Iron

Application