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

U.S. Environmental Protection Agency
U.S. EPA Technology Innovation and Field Services Division


Anaerobic Bioremediation (Direct)


Case Study Histories from the FRTR Cost and Performance Database
This is a selection of sites that used in situ anaerobic bioremediation to address chlorinated volatile and some metal contamination.

Adobe PDF LogoBiodegradation of Dense Non-Aqueous Phase Liquids (DNAPLs) through Bioaugmentation of Source Areas - Dover National Test Site, Dover, Delaware: ESTCP Cost and Performance Report
Environmental Security Technology Certification Program (ESTCP), Project ER-0008, 59 pp, Aug 2008

This demonstration was conducted to determine if bioaugmentation can stimulate complete dechlorination of a DNAPL to nontoxic end products, as well as increase the mass flux from a source zone when biological dehalorespiration activity is enhanced through nutrient addition and/or bioaugmentation. The demonstration was able to prove that biological systems can be applied to promote enhanced dissolution of a PCE DNAPL source zone. Conservatively, the study appears to demonstrate an average increase in mass discharge ranging from 2.2 to 4.5 during the bioaugmentation phase relative to baseline (groundwater extraction only) conditions. If the increase in degradation rates is insufficient to enhance DNAPL removal significantly, rapid biodegradation of the high VOC concentrations typically encountered in DNAPL source zones will provide biological containment of the groundwater plume, thereby reducing cleanup times and/or reducing the O&M cost of conventional containment using pump and treat.

Bioremediation of Source Zone and Migrated Plumes
Blomgren , N., P.K. Juriasingani, and J.R. Woertz.
Third International Symposium on Bioremediation and Sustainable Remediation Technologies, 18-21 May 2015, Miami, Florida. Poster abstract, 2015

The former Unocal distribution facility in Wichita, Kansas, blended and packaged bulk chemicals for industrial customers. During historical operations, PCE was released to the site groundwater. Remedial technologies implemented at the site since 1989 to treat chlorinated VOCs in the groundwater include SVE, P&T, excavation, bioremediation, and phytoremediation. Despite these measures, contaminated groundwater has migrated a quarter mile from the primary source area to adjacent properties. During annual groundwater monitoring conducted in 2013, PCE and its daughter products were present at concentrations over 10,000 µg/L. A phased treatment approach is being implemented at the site. EHC® and EHC® Liquid were selected to stimulate both biodegradation and chemical reduction. Baseline monitoring was conducted in June 2014, and the first round of injections began in July 2014. A total of ~29,500 lb EHC (as 30% slurry) and 1,850 gal EHC Liquid (diluted to make a 5% solution) were injected among six barriers and one injection grid through 165 injection points over a one-month period. Performance monitoring results (Nov 2014 and Mar 2015) indicate the amendments are conditioning the aquifer to promote reductive dechlorination. Additional information: Interim Measure Injection Completion Report, Former Unocal Chemical Distribution Facility (2015)Adobe PDF Logo and Interim Measure Performance Monitoring Report, March 2015 EventAdobe PDF Logo

Adobe PDF LogoCase Study: In Situ Accelerated Anaerobic Bioremediation
Bloom, B. Lyon, and L. Stenberg.
E2S2 2010: Environment, Energy Security, and Sustainability Symposium and Exhibition, 14-17 June 2010, Denver, Colorado. National Defense Industrial Association (NDIA), Abstract 9778, 34 slides, 2010

Accelerated anaerobic bioremediation (AAB) was applied at Dover AFB to a large, multi-source plume of chlorinated ethenes and some ethanes. The Area 6 plume is ~1 mile in length and over 1,000 feet wide and originates from at least 5 separate source areas that commingle in the subsurface. Remediation involved targeted direct AAB injection of a substrate mixture of sodium lactate, EVO, and nutrients in source areas. After 3 years of treatment, plume-wide degradation is being observed. PCE and TCE concentrations within the AAB treatment areas have declined by over 80% in many wells, and the presence of ethene is increasing in areal extent over time. See longer abstract; More InformationAdobe PDF Logo

Adobe PDF LogoChallenges in Planning for Groundwater Remedy Transition at a Complex Site
O'Steen, W.N. and R.O. Howard, Jr. U.S. EPA Region 4, 12 pp, 2014

Complex groundwater contamination sites require comprehensive, structured groundwater monitoring in planning for transition to a new groundwater remedy. This paper provides as an example the Medley Farm Superfund site, a former waste solvent dump located in South Carolina. PCE, TCE, and their degradation products in the groundwater were addressed with pump and treat from 1995 to 2004. Between October 2004 and April 2012, injection of a lactate solution to promote enhanced reductive dechlorination (ERD) was conducted on multiple occasions, with positive responses in hydrogeochemistry and groundwater quality. In 2012, EPA issued an amended ROD, changing the groundwater remedy to ERD. MNA was selected as a contingency remedy in anticipation that as cleanup progresses, ERD may transition to MNA. Restructuring the site's monitoring and data evaluation program will enable EPA to discern treatment effects more clearly and facilitate MNA evaluation.

Adobe PDF LogoCombining Low-Energy Electrical Resistance Heating With Biotic and Abiotic Reactions for Treatment of Chlorinated Solvent DNAPL Source Areas
Macbeth, T., M.J. Truex, T. Powell, and M. Michalsen.
ESTCP Project ER-200719, 383 pp, 2012

Low-temperature subsurface heating was combined with either ZVI or in situ bioremediation to enhance DNAPL remediation performance through both increased degradation reaction rates and contaminant dissolution. Moderate heating and minor operational costs enhanced efficiency and effectiveness of in situ treatment of TCE. Capture and treatment of contaminated vapor—a major cost element of standard thermal treatment—was not needed as the heating infrastructure was limited to subsurface electrodes and a power control unit. See also the 2015 ESTCP Cost & Performance ReportAdobe PDF Logo

Adobe PDF LogoComparative Demonstration of Active and Semi-Passive In Situ Bioremediation Approaches for Perchlorate Impacted Groundwater: Active In Situ Bioremediation Demonstration (Aerojet Facility)
Cox, E. and T. Krug.
ESTCP Project ER-200219, 848 pp, 2012

During the demonstration of active enhanced in situ bioremediation at the inactive Rancho Cordova test site in California, groundwater containing perchlorate and TCE was extracted from the shallow aquifer, amended with ethanol, and recharged to the shallow aquifer. The active biobarrier provided treatment and containment of a 600-ft wide section of the plume in the shallow aquifer using two groundwater extraction wells and a single groundwater recharge well. Indigenous bacteria were able to biodegrade perchlorate concentrations as high as 4,300 µg/L to less than 4 µg/L within 50 ft of the recharge well. TCE dechlorination followed bioaugmentation of the shallow aquifer with KB-1 to introduce dehalorespiring bacteria.

Degradation of Carbon Tetrachloride in the Presence of Zero-Valent Iron
Alvarado, J.S., C. Rose, and L. LaFreniere. Journal of Environmental Monitoring, Vol. 12, No. 8, p. 1524-1530, 2010

Efforts to achieve the decomposition of carbon tetrachloride through anaerobic and aerobic bioremediation and chemical transformation have met with limited success because of the conditions required and the formation of hazardous intermediates. After using particles of zero-valent iron (ZVI) with limited success for in situ remediation of carbon tetrachloride, the authors investigated the application of a modified microparticulate product that combines controlled-release carbon with ZVI for stimulation of in situ chemical reduction of persistent organic compounds in groundwater. With this product, physical, chemical, and microbiological processes were combined to create very strongly reducing conditions that stimulate rapid, complete dechlorination of organic solvents. In principle, the organic component of ZVI microparticles is nutrient rich and hydrophilic and has high surface area capable of supporting the growth of bacteria in the groundwater environment. The investigators found that as the bacteria grew, oxygen was consumed, and the redox potential decreased to values reaching -600 mV. The small modified ZVI particles provide substantial reactive surface area that, in the conditions of the study, directly stimulates chemical dechlorination and cleanup of the contaminated area without accumulation of undesirable breakdown products. The objective of this work was to evaluate the effectiveness of ZVI microparticles in reducing carbon tetrachloride under laboratory and field conditions. Changes in concentrations and in chemical and physical parameters were monitored to determine the role of the organic products in the reductive dechlorination reaction. Results of laboratory and field studies are presented.

Adobe PDF LogoDesigning, Assessing, and Demonstrating Sustainable Bioaugmentation for Treatment of DNAPL Sources in Fractured Bedrock: ESTCP Cost and Performance Report
ESTCP Project ER-201210, 100 pp, 2017

A small portion of a (presumably) much larger PCE source area was targeted at Edwards AFB, Calif., and the DNAPL mass and distribution were quantified in two separate depth intervals with discrete fractures. Geophysical testing showed that the well capacities within the source area were sufficient to distribute the amendments in conductive fractures and that there was hydraulic connectivity in both zones in the two wells used for the field test. During biological treatment (SDC-9 culture), enhanced dissolution of the DNAPL sources was observed in both the shallow and deep fractures intervals. In the shallow fracture zone, the measured DNAPL mass removal was ~100%, but only 45% over the same period in the deep zone. This difference in mass removal was attributed to the DNAPL architecture, as the flow field in the deep zone was more complex, and more DNAPL was present in mass transfer controlled zones. Rebound testing showed no increase in the sum of chlorinated ethenes and ethane in the shallow zone 10 months after active treatment, but concentrations did rebound significantly in the deep zone, likely owing to residual DNAPL mass.

Adobe PDF LogoDirect-Push Injection and Circulation Biobarrier to Remediate a TCE Groundwater Plume
Kovacich, M., D. Beck, and P. Rich (GeoTrans, Inc.); M. Zack and M. Cannert (Visteon Corporation). Proceedings of the 5th International Conference on Remediation of Chlorinated and Recalcitrant Compounds, Monterey, California, May 2006, Battelle Press, Columbus, OH.

A study was conducted to determine if direct-push drilling methods combined with a ground-water circulation system could be used to establish a passive biobarrier in a very transmissive aquifer contaminated with trichloroethene (TCE) at a site located in central Indiana. The site has a plume consisting primarily of dissolved-phase TCE that is approximately 1,100 feet wide, 6,300 feet long, and up to 50 feet deep. The horizontal groundwater flow velocity is estimated to be 2.0 to 5.0 feet/day. Site geochemical and volatile organic compound (VOC) data showed no evidence of the natural attenuation of TCE. After a bench-scale test indicated that bioaugmentation could be applied successfully at the site, emulsified vegetable oil with 5% lactate was applied via direct-push injection at 14 drive points in the upgradient portion of a circulation cell. Positive results were evident within weeks, suggesting that the combination of direct injection and circulation accelerated the establishment of the biobarrier. Halorespiring bacteria have been quantified in the circulation area using real-time polymerase chain reaction techniques. Recent VOC, geochemical, and microbial data indicate that the biobarrier has persisted in the circulation zone more than six months after system shut-down. These results led the Indiana Department of Environmental Management to approve a work plan for full-scale implementation of biobarriers at the site.

Adobe PDF LogoEdible Oil Barriers for Treatment of Chlorinated Solvent Contaminated Groundwater
Lieberman, M.T. 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 g/kg TCE in soil and >20,000 g/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 M to 17 M, a decline of 91%. See also the ESTCP Cost and Performance ReportAdobe PDF Logo.

Adobe PDF LogoEnhanced Amendment Delivery to Low Permeability Zones for Chlorinated Solvent Source Area Bioremediation
Adamson, D., C. Newell, M. Truex, and L. Zhong.
ESTCP Project ER-200913, 202 pp, 2014

A demonstration of the use of shear-thinning fluid based technology to improve treatment within low-permeability (low-k) zones of heterogeneous subsurface environments was conducted in a test cell within the Area D TCE plume at Joint Base Lewis-McChord. Low-k zones, which can serve as a long-term secondary source of contamination when transport is diffusion-controlled, are difficult to target using standard injection-based treatment approaches. A shear-thinning fluid can be used to distribute a bioremediation amendment (e.g., lactate) around an injection well such that the solution achieves better penetration and delivers the amendments to zones of both high and low permeability. When injected at a relatively high velocity compared to natural groundwater flow velocities, the shear-thinning nature of the solution allows it to flow more readily, promoting cross-flow from high- to low-permeability zones. During the demonstration, the shear-thinning fluid improved amendment distribution by ~41% with enhanced persistence and treatment effectiveness within the lower-k zones of the heterogeneous aquifer. Permeability contrasts of 1-2 orders of magnitude may be amenable to this technology (e.g., improving distribution to silt layers within a sand matrix, but not clay layers). Field work began in August 2013, and performance monitoring events were completed in February and May 2014. Additional Information: ESTCP Cost and Performance ReportAdobe PDF Logo

Adobe PDF LogoEnhanced Attenuation of Unsaturated Chlorinated Solvent Source Zones Using Direct Hydrogen Delivery
Newell, C.J., A. Seyedabbasi, D.T. Adamson, T.M. McGuire, B. Looney, P.J. Evans, J.B. Hughes, M.A. Simon, and C.G. Coyle.
ESTCP Project ER-201027, 532 pp, 2013

Over a 6-month test period, a total of 830,000 standard cubic feet of gas—10% hydrogen, 79% nitrogen, 10% propane, and 1% carbon dioxide—was injected into a fine-grained vadose zone at a former missile silo site in Nebraska . The hydrogen gas was designed to stimulate biodegradation of TCE and its breakdown products that persisted after three years of SVE. Although the system was successful at converting TCE, a "cis-DCE stall" condition occurred. ESTCP Cost & Performance ReportAdobe PDF Logo

Enhancing Reductive Dechlorination with Nutrient Addition
Fowler, T. and K. Reinauer.
Remediation Journal 23(1):25-35(2013)

This paper presents three case studies where the addition of a balanced macro- and micro-nutrient source (e.g., BounTA) substantially accelerated the biodegradation of chlorinated ethenes (TCE, PCE), independent of the electron-donor substrate (i.e., sodium lactate, EHC®, ethyl lactate) applied. [This paper is Open Access via the "Get PDF" link.]

Adobe PDF LogoFinal Report for the Enhanced Anaerobic Bioremediation Pilot Test, Bountiful/Woods Cross Superfund Site, Bountiful, Utah
Bureau of Reclamation, Denver, CO. 66 pp, 2006

This biostimulation/bioaugmentation pilot study to address TCE contamination involved a side-by-side comparison in 3 test cells of 3 different bioremediation substrates: sodium lactate, chitin, and emulsified soybean oil. Following the first round of substrate injection and sampling, all 3 test cells were inoculated with a commercially available dechlorinating culture containing Dehalococcoides ethenogenes. Based on the results of the pilot test, full-scale enhanced anaerobic bioremediation was selected for the site's 2006 Record of Decision. Emulsified oil is recommended as the electron donor.

Fracture-Emplacement and 3-D Mapping of a Microiron/Carbon Amendment in TCE-Impacted Sedimentary Bedrock (Abstract)
Bures, G., J.A Skog, D. Swift, J. Rothermel, R. Starr, and J. Moreno
Seventh International Conference on Remediation of Chlorinated and Recalcitrant Compounds (Monterey, CA; May 2010)

An in situ pilot remediation project was carried out on behalf of the U.S. Army Corps of Engineers (Omaha District) at the F.E. Warren Air Force Base Former Atlas E Missile Site No. 12 in Colorado. Between 6,000 and 32,000 lbs of microiron/carbon amendment was emplaced at each borehole by mixing it as a biodegradable, linear protein gel slurry to carry the amendment in a uniform suspension. Hydraulic fracturing was conducted in 9 pre-drilled boreholes to deliver the amendment slurry at 5-ft increments between depths of 35 to 63 ft in bedrock. Hydraulic fracturing was successful in emplacing greater than 98% of the total design mass of 205,550 lb. of EHC-G zero valent micro-iron/carbon within TCE-impacted bedrock sediments across an area of approximately 64,000 ft2. The implications of this work are that massive quantities of micro-iron (or other) amendments can be cost-effectively emplaced in challenging geologic environments (e.g., deep bedrock) to treat large plume areas using few injection borings.

Adobe PDF LogoGeophysical Imaging for Investigating the Delivery and Distribution of Amendments in the Heterogeneous Subsurface of the F.E. Warren AFB
Kelley, B., S. Hubbard, J. Ajo-Franklin, J. Peterson, Y. Wu, E. Gasperikova, B. Butler-Veytia, V. Shannon, and R. Coringrato.
ESTCP Project ER-200834, 80 pp, 2012

In 2009, a remedial action involving hydraulic fracturing and in situ bioremediation was conducted at Spill Site 7, the location of a TCE plume at F.E. Warren AFB. The June 2010 field demonstration involved an evaluation of the progress of in situ bioremediation (HRC[r]) via hydraulic fracturing and the use of geophysical imaging (time-lapse electrical resistivity tomography and seismic datasets) to monitor fracture emplacement and amendment distribution at the site. Additional information: ESTCP Cost & Performance ReportAdobe PDF Logo

Adobe PDF LogoGroundwater Remediation Startup Report, Site Monitoring & Performance Evaluation Report, Revision 1.0: Chemical Injections & Attenuation Monitoring, 2nd & Kirby Site, Hutchinson, Kansas
Kansas Department of Health & Environment (KDHE), Topeka. 235 pp, 2015

Dissolved-phase TCE and related contaminants have been found in the site groundwater at this truck transportation facility. The site contractor used direct-push injections to introduce emulsified vegetable oil (EVO) to provide the electron donor needed to produce the reducing and anaerobic conditions that stimulate contaminant biodegradation. A total of ~9,000 gal of EVO-water solution (900 gal EVO product, specifically SRS®-FRL) was injected throughout the course of the project. The presence of cDCE as a degradation product of TCE indicates some degree of ongoing reductive dechlorination. This report details the specific measures applied to accelerate the chemical and biological degradation of TCE in the site groundwater.

Adobe PDF LogoA Hydrogen Recirculation System for the Treatment of TCE-Impacted Groundwater
Aziz, C. E., S.K. Farhat, E.A. Higgins, C.J. Newell, and J. Hansen. Proceedings of the Seventh International In Situ and On-Site Bioremediation Symposium (Orlando, FL; June 2003), 6 pp, 2003

To speed the rate of reductive dechlorination of trichloroethylene (TCE)-impacted groundwater at the Old Jet Engine Test Site, Offutt AFB, Nebraska, an in situ pilot-scale dissolved hydrogen addition system was installed. The test area consisted of an injection well, a recovery well, and five monitoring wells within an 8.5 mx 4.3 m (28 ft x 14 ft) test plot. Groundwater was pumped from the recovery well at a flow rate of 1.5 L/min (0.4 gpm), amended with hydrogen at 20 mL/min, and injected into the injection well, thereby creating a recirculation system. The results of the first 6months of operation are presented in this paper. After 6 months of operation, the oxidation-reduction potential and dissolved oxygen of the groundwater decreased. Despite background sulfate levels of 280 mg/L, the mean TCE concentration declined 63% from 2.9 µmol/L to 1.07 µmol/L. Significant production of cis-1,2-dichloroethene (cDCE) was observed within the test area (i.e., 0.7to 3.0 µmol/L), indicating that the hydrogen was promoting reductive dechlorination. The cDCE:TCE ratio increased more than tenfold from 0.25 to 2.8, despite decreasing groundwater temperatures. In summary, the dissolved hydrogen recirculation system was effective in removing TCE from groundwater without significant vinyl chloride production.

Adobe PDF LogoImproving Effectiveness of Bioremediation at DNAPL Source Zone Sites by Applying Partitioning Electron Donors (PEDS)
Lebron, C.A ., D. Major, M. McMaster, and C. Repta.
ESTCP Project ER-200716, CR-NAVFAC-EXWC-EV-1402, 3,859 pp, 2014

Partitioning electron donors (PEDs) are water-soluble electron donors that partition directly into a target DNAPL to effect enhanced in situ bioremediation. A PED technology field demonstration was conducted at a TCE source zone at NASA Launch Complex 34 using n-butyl acetate (nBA), a colorless liquid that volatilizes to form dense vapors that have the potential to form an explosive mixture with air. Introduced to the source area using direct-push injection equipment, nBA was able to promote biodegradation and achieved sustained production of dechlorination products, even in the presence of co-contaminant 1,1,2-trichloro-1,2,2-trifluoroethane (CFC113). This project showed that nBA can (1) achieve high rates of biologically enhanced DNAPL dissolution; (2) be easily and effectively delivered; and (3) sustain donor supply at an effective concentration at the DNAPL:water interface to promote the growth and activity of the dechlorinating biomass. [Note: See the first 112 pages of the PDF file for the main report; the subsequent appendices contain lab forms, boring logs, and other field data.] Additional information: ESTCP Cost and Performance ReportAdobe PDF Logo.

Adobe PDF LogoIn Situ Bioremediation of Chlorinated Ethene DNAPL Source Zones: Case Studies
Interstate Technology & Regulatory Council (ITRC) Bioremediation of DNAPLs Team.
BioDNAPL-2, 173 pp, 2007

Contains the following case studies: (1) cleanup of a TCE residual source area and a dissolved-phase plume at the Test Area North site of Idaho National Engineering and Environmental Laboratory; (2) a pilot-scale demonstration to evaluate the effects of biological activity on enhancing dissolution of an emplaced PCE DNAPL source at Dover National Test Site; (3) a TCE cleanup field study at Cape Canaveral's Launch Complex 34, Kennedy Space Center; (4) a PCE demonstration project undertaken by ARCADIS at a private-sector U.S. site; (5) a cleanup of PCE groundwater impacts at an active dry cleaner located in a strip mall in Portland, OR; and (6) use of Emulsified Oil Substrate (EOS®) to remediate a TCE source area at the Tarheel Army Missile Plant, Burlington, NC.

Adobe PDF LogoIn-Situ Substrate Addition to Create Reactive Zones for Treatment of Chlorinated Aliphatic Hydrocarbons: Hanscom Air Force Base
Lutes, C.C., V. D'Amato, A. Frizzell, M. Hansen, G. Gordon, P. Palmer, and S. Suthersan.
Environmental Security Technology Certification Program (ESTCP), 431 pp, 2003.

The general purpose of this demonstration project was to evaluate the efficacy of the In-Situ Reactive Zone/Enhanced Reductive Dechlorination (IRZ/ERD) technology to remove TCE from impacted groundwater in a range of geologic conditions and TCE concentrations. The active treatment phase of the demonstration took place from October 2000 to October 2002, during which time 47 injections conducted in a single injection well delivered 1,250 gallons of raw blackstrap molasses, 11,250 gallons of dilution water, 7,575 gallons of push water, and 4,732 grams of potassium bromide. During the two-year demonstration project, complete TCE removal was observed in a source area that had a long history of fairly stable TCE concentrations before treatment.

Adobe PDF LogoIn-Situ Substrate Addition to Create Reactive Zones for Treatment of Chlorinated Aliphatic Hydrocarbons: Vandenberg Air Force Base
Lutes, C.C., A. Frizzell, B. Molnaa, and P. Palmer.
Environmental Security Technology Certification Program (ESTCP). 335 pp, 2004.

This report documents an evaluation of the efficacy of the In-Situ Reactive Zone/Enhanced Reductive Dechlorination (IRZ/ERD) technology in removing TCE from impacted ground water in a range of geologic conditions and TCE concentrations. The active treatment phase of the demonstration took place between February 2001 and April 2003. A total of 683 gallons of raw molasses, 6,830 gallons of dilution water, 1,500 gallons of push water, 7,718 grams of potassium bromide tracer and 669 pounds of NaHCO3 buffer were injected into three injection wells. Thirty one injections were completed. During the active treatment period and up to 10 months after the last injection, the treatment system demonstrated slow but effective TCE removal via bioremediation. The dissolved phase plume showed very limited TCE degradation before treatment.

Limited-Access Bioremediation in a Factory Setting
Farnsworth, D.R., W.A. Murray, and D.L. Bronson.
Proceedings of the Annual International Conference on Soils, Sediments, Water and Energy, Vol 15 Article 2, 7 pp, 2010

At a factory in New Hampshire, TCE released through a storm-water outfall pipe contaminated the groundwater. Tight soils, shallow water table, access limitations, and a pending property sale complicated the cleanup. Due to the low permeability of the soil, effective introduction of the Hydrogen Release Compound (HRC) required many injection points and applications. After the start of HRC application, VOC levels at the outfall dropped to below the state regulatory standard. The treatment has not interfered with site activities or the sale of the property, and site closure is expected to be completed in a reasonable timeframe.

Adobe PDF LogoLow Cost Bioremediation Using Dextrose and Recirculation to Treat PCE-Contaminated Groundwater at Drycleaners
Hanson, D. Oregon Department of Environmental Quality SCRD Fall Meeting, Austin, Texas, 2006

This presentation discusses enhanced anaerobic bioremediation using dextrose at two dry cleaning sites in Oregon. The NuWay II Cleaners pilot project involved delivery of dextrose into a recirculation system continuously (about 480 mg/L dextrose solution). Reductive dechlorination was observed. After five months, PCE and TCE concentrations declined from over 100 to less than 10 µg/L; DCE and VC concentrations increased from less than 10 to greater than 10 µg/L; and ethene/ethane concentrations increased from less than 1 µg/L to below10 µg/L. The pilot system has continued to treat chlorinated solvents 11 months after recirculation ceased. The Plaza Cleaners Removal full-scale project involved excavation of source soil to the water table. About 4,800 lbs of dextrose were injected into a groundwater recirculation system in weekly batches (with nutrients). After 58 days of treatment PCE concentrations fell from 2,700 ppb at baseline to 170 ppb, with no buildup of TCE. A rapid conversion to DCE was observed. At both sites, greater success was observed with recirculation (extraction, amendment, and then re-injection) over gravity feed/slug injections.

Adobe PDF LogoPost-Remediation Evaluation of EVO Treatment: How Can We Improve Performance?
Borden, R.C.
ESTCP Project ER-201581, 151 pp, 2017

Field, lab, and design evaluations of emulsified vegetable oil (EVO) use for enhanced reductive dechlorination (ERD) of TCE contamination at two sites at the former Naval Training Center Orlando are presented. Although the remediation systems at both sites initially achieved substantial reductions in TCE concentrations, concentrations of cDCE and VC increased in some wells due to TCE degradation and remain elevated. Results from the project evaluations were used to identify the reasons for the ERD systems' failure to meet cleanup goals and to develop new approaches and procedures to improve performance.

Adobe PDF LogoRemedial Action Completion Report (CDRL A001B) and Preliminary Closeout Report, Former Air Force Plant PJKS, Waterton Canyon, Colorado
Air Force Center for Engineering and the Environment, 44 pp, 2013

A pilot study conducted at PJKS in 2004-2005 to evaluate the effectiveness of in situ anaerobic reductive dechlorination (ARD) of TCE and NDMA in bedrock source areas showed a decline in TCE contamination, which in 2006 led to the expansion of an interim corrective measure to stimulate ARD in the D-1 area groundwater plume. Horizontal and vertical injection wells delivered sodium lactate, emulsified edible oil (EEO), nutrients, and Dehalococcoides (dhc) to the Fountain Formation aquifer. In 2008, two full-scale biobarriers were constructed via injection of EEO, sodium lactate, and dhc into direct-push boreholes to target the alluvial transition groundwater areas, provide a barrier to plume migration, and further deplete TCE contamination in the downgradient plume. A technical impracticability waiver is recorded in the ROD for NDMA in the crystalline bedrock due to geological and technological limitations, although the VOCs in the bedrock are expected to meet MCLs. Additional information: PJKS EE/CA (2005)Adobe PDF Logo; Focused Feasibility Study (2010)Adobe PDF Logo; Case Study Slides (2012)Adobe PDF Logo

Adobe PDF LogoSolar-Powered Remediation and pH Control: ESTCP Cost and Performance Report
ESTCP Project ER-201033, 73 pp, 2017

The primary project goal was to demonstrate a solar-powered technology—Proton Reduction Technology (PRT)—to generate hydrogen in situ and reduce aquifer acidity to promote reductive dechlorination. During operation, PRT uses a low voltage potential applied across electrodes installed within an aquifer to impress a direct current in the subsurface. PRT was tested on a plume of dissolved-phase TCE and cis-DCE in a low-pH aquifer at Joint Base McGuire-Dix-Lakehurst, New Jersey. The demonstration used electrodes inserted into PVC wells within the contaminated low-pH aquifer for 507 days of operation coupled with aquifer bioaugmentation to ensure the presence of dechlorinating bacteria to support biodegradation. Solar panels and deep-cycle 12-volt batteries provided electricity to operate the system. PRT resulted in partial reductive dechlorination of CVOCs in the low-pH aquifer, but TCE dechlorination was incomplete under the demonstration conditions, which was attributed to the borderline pH and reducing conditions achieved.

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