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Guaranteed and Standard Fixed Price Remediation of DNAPL and LNAPL using Electrical Resistance Heating (ERH) at U.S. Military Bases

Guaranteed Fixed Price Remediation ofPCE DNAPL — U.S. Navy Base CharlestonCharleston, South Carolina

SummaryERH was conducted underneath and immediately adjacent to Building1189, the former Base dry cleaning operations, for remediation ofCVOCs, including PCE andTCE (Figure 1). The goalwas to reduce CVOCs ingroundwater by an aver-age of 95%.

DescriptionPCE migrated downward as DNAPL through fill and shallow subsurfaceand accumulated on top of and within the clay layer. Surface area oftreatment was approximately 18,000 ft2 with a subsurface vertical treat-ment interval from 2 to 11-ft bgs (one foot into the semi-confining claylayer).

ResultsFigure 2 represents baseline PCEconcentrations (>500 µg/L) ingroundwater at the Charleston site.The ERH system was shutdown inJuly 2002. Following ERH, CH2MHillconducted an enhanced reductivedechlorination (ERD) pilot test usinglactate. Based on the successfulpilot test, the ERD remediation wasperformed on a full-scale through-out the former ERH treatment region. Figure 3 shows the dramaticdecrease in PCE concentrations 22 months after ERH in March 2004.

Abstract: ERH is a remediation technology where soil andgroundwater is heated by the passage of current through satu-rated and unsaturated soil between the electrodes, not by theelectrodes themselves. It is the resistance to the flow of elec-trical current that results in increased subsurface tempera-tures, and this is typically applied to the boiling point of thecontaminant and water. Steam is created in situ and contami-nants are directly volatilized and/or recovered to the surfaceas free product.

This poster provides a series of case studies of a variety ofprojects that have involved the remediation of DNAPL andLNAPL using ERH at U.S. Military Bases in the past eight years.Site background and data collected will be presented. Severalof these projects were conducted using Guaranteed FixedPrice Remediation (GFPR) contracts.

SummaryThere were three LNAPL/DNAPL source areas at the Ft. Lewis, East GateDisposal Yard (EGDY) NPL site. Contaminants of concern in NAPL Areas 1,2 and 3 included chlorinated solvents, primarily trichloroethene (TCE),and POLs (petroleum products, oil and lubricants). Based upon pre- andpost-ERH sampling, all remedial objectives were met for each NAPL Areaand average TCE concentrations in groundwater were reduced by 99.9%,99.0% and 99.97%, respectively. This complex, multi-step ERH projectwas performed under a guaranteed fixed price remediation (GFPR) con-tract. Using a Triad management approach and applying lessons learnedheating each NAPL area; TRS realized significant project savings for theArmy. The Society of American Military Engineers presented the projectteam with their Silver Design Excellence Award.

DescriptionERH was applied sequentially in the three separate NAPL Areas (Figure1). Area 1 measured 25,400 ft2 and heating extended from 2 to 38 feetbelow ground surface (ft bgs). Area 2 was 22,390 ft2 with a treatmentinterval of 2 to 43-ft bgs. Area 3 covered 18,200 ft2 and treatmentextended from 2 to 30-ft bgs. The volumes treated in NAPL Areas 1, 2and 3 were 35,040, 36,000 and 20,200 yd3, respectively. Site lithologywas very unpredictable and groundwater flow in the highly transmissiveaquifer was as high as 10-20 feet per day in each NAPL Area. The aver-age depth to groundwater in all three areas was 7-ft bgs.

The project team used a Triad management approach that combined flex-ible designs and work plans, rapid data turnaround times, and a webbased data presentation system. This approach allowed the team toincorporate nationally recognized research programs on the in situ biolog-ical and abiotic destruction of TCE into the project. Throughout the proj-ect, system improvements were evaluated and implemented rapidly tokeep on schedule, maximize project performance, and save the Armymoney.

ResultsGroundwater TCE concentrations in NAPL Areas 1, 2, and 3 were reducedby 99.9% , 99.0%, and 99.97% respectively. Almost 2 years followingERH, TCE concentrations in groundwater continued to decline in all threeNAPL Areas. Figure 2 shows TCE concentrations in all three NAPL Areasand the averages before ERH, immediately after ERH, and twenty-twomonths after heating.

ESTCP Funded ResearchAdditional research presently underway is designed to study thebiodegradation and zero valent iron dechlorination pathways during andpost ERH heating. Two separate test sites at the EGDY have been identi-fied and electrodes will be installed in early December 2008. The studydesign calls for heating to 50—60ºC and ERH operations are scheduledto begin in Spring of 2009.

Partners include: Army Corps of Engineers, Northwind Environmental andTRS.

Standard Fixed Price Remediation of TCE DNAPL under an Operating Industrial Manufacturing Facility — Air Force Plant 4Fort Worth, Texas

SummaryTRS designed, installed and operated a full-scale ERH remediation system covering an area of about 1/2 acre inside Building 181 at Air Force Plant 4 inFort Worth, TX. This is the most complex application of ERH ever completed inside and underneath an operating, heavy industrial manufacturing facility. Thecleanup objectives for the full-scale remediation were to reduce average TCE concentrations in soil and groundwater to 11.5 mg/kg and 10 mg/l, respec-tively. The groundwater remediation goal was met following five months of ERH operations and the soil remediation goal was met in November 2002, with a90% reduction in contamination levels.

DescriptionThe ERH system was installed inside Building 181 (Figure 1). The design parameters were precise in the placement of electrodes and many were installedon as much as a 32° angle underneath manufacturing equipment, chemical bath tanks, and piping racks. The production of Air Force Fighter Jets insideBuilding 181 operates 24 hours a day/7 days a week and workers were allowed access directly over the ERH area during operations.

Figure 1 shows the pilot test area and full-scale remediation. The treatment interval extended from approximately 4 to 37-ft bgs into the top of the compe-tent limestone bedrock (Walnut Formation).

The air inside Building 181 was sampled and ana-lyzed using a gas chromatograph and photo acousticmulti gas analyzer (PMA) during operations. Mostmeasurements were collected on an automatic 5minute cycle, 24 hours per day throughout the dura-tion of the remediation. No TCE or other VOC detec-tions occurred in the indoor air at a detection limit of1 ppmv during the pilot or full-scale operations.

ResultsThe groundwater remediation goal was met followingfive months of ERH operations and the soil goal wasmet in November 2002, with a 90% reduction in con-tamination levels (Figures 2 and 3).

Guaranteed Fixed Price Remediation of PCE in Soil — Site 22 Naval Station Great LakesNorth Chicago, Illinois

SummaryTRS performed an ERH remediation of PCE-contaminated in tight silt-clay soil at the Site 22Naval Station in Great Lakes, IL . The guaranteed performance based remedial criteriarequired all PCE concentrations to be less than 20 mg/kg - a 95.5% reduction of PCE insoil to meet the Illinois EPA Tiered Approach to Corrective Action Objectives (TACO) industri-al/commercial criteria. The remedial goal was surpassed within four months of ERH opera-tions with an average of 4.09 mg/kg PCE measured in soil or a 99.6% average reduction ofPCE concentrations in soil.

DescriptionSite 22 consisted of an old dry cleaning facility that operated in former Building 105. The building was demolished and the surrounding lot is used forvehicle parking. The remediation area was located in the southeastern portion of the active parking lot and consisted of three regions. The total treat-ment area was approximately 2,400 ft2, the average depth interval was from 0.5 to 17-ft bgs, and the resulting total treatment volume was approxi-mately 1,400 yd3. To mitigate heat losses and enhance performance in the shallow contamination area, a Styrofoam cover was placed on the surfaceof the treatment region (see Figure 1).

ResultsThe estimated pre-ERH mass of CVOCs in the treatment vol-ume was 1,200 - 1,500 pounds. Vapor sampling indicatedthat 1,159 pounds of PCE was removed by ERH with no sam-ples exceeding an 8 lb/hr requirement.

Soil samples were collected at 15 sampling locations withinthe treatment area. Sampling indicated that the concentrationof PCE was reduced by an average of 99.08% in just over fourmonths of ERH operations. Figure 2 illustrates PCE concentra-tions in soil before and after the application of ERH.

Standard Fixed Price Remediation of TeCA in Sandstone Bedrock —US Naval Station Annapolis, Annapolis, Maryland

SummaryTRS performed an ERH source area remediation of 1,1,2,2-Tetrachloroethane (TeCA) andTrichloroethene (TCE) in soil, fractured rock and groundwater at an average depth of 29 to70-ft bgs. Cemented sandstone with a hard cemented iron layer was located between 40 to65-ft bgs. The remedial goal was an average 95% reduction in the TeCA and TCE mass insoil. The project was completed 20 days ahead of schedule and under budget.

DescriptionTeCA, at elevated temperatures, rapidly converts to TCE through a water substitution reaction called hydrolysis. During hydrolysis, TeCA reacts directlywith water or soil moisture, without regard to redox conditions, and no inorganic or biochemical catalysts are required. During ERH, the conversion ofTeCA to TCE proceeds very rapidly as the subsurface begins to heat, leaving the predominate mass removed as TCE, with TeCA forming only a small por-tion of the extracted VOCs. One pound of TeCA forms 0.78 pounds of TCE as determined by chemical stoichiometry.

ResultsThis remediation occurred in a busy alley and fire lane behind the baseCommissary which remained open to traffic throughout the ERH remedia-tion. After less than two months of heating, three interim soil sampleswere collected inside the treatment region to check the progress of theremediation and contained non-detect (ND) levels of chlorinated volatileorganic compounds (CVOCs). The Navy elected to continue to operate theERH system for another two months and collect confirmatory samplingone year later. Sampling results showed average total CVOC concentra-tions in soil had been reduced by 99.9% (Figure 2).

Standard Fixed Price Remediation ofChlorinated Solvents and BTEX — NavalWeapons Industrial Reserve PlantBedford, Massachusetts

SummaryThis project was conducted in two phases:a pilot test on Site 3 for CVOCs in ground-water, followed by a full-scale ERH reme-diation on Site 4 to treat BTEX compoundsin groundwater. Site 4 remediation goalswere to reduce Benzene concentrations ingroundwater to 50 µg/l.

ResultsWhile Site 4 was determined to be a BTEXgroundwater contamination source area,the only established reduction goal was forthe benzene constituent. Energy input viathe design electrode configuration resultedin achieving benzene boiling temperaturesin groundwater. Consequently, the Site 4ERH remediation system was successful inachieving the benzene cleanup goal (Figure2). It should be noted that there was signif-icant (i.e., greater than 10 percent) reduc-tion in all BTEX constituent concentrationlevels (Figure 3), as a result of the ERHremediation.

Standard Fixed Price DNAPL RemovalAction — Alameda Navy BaseAlameda, California

SummaryPlume 4-2 has been impacted by DNAPL consisting of vinyl chloride,DCA, DCE, TCA, TCE, and PCE as well as daughter products (SA’s). A SixPhase Heating (SPH) remediation was installed and operated to reducethe groundwater concentrations of SA’s to below 10,000 µg/l (Figure 1).

DescriptionThe region was locatedunder and adjacent toBuilding 350, support-ed by concrete piers(Figure 2) that suspendthe floor of the buildingabove grade. Electrodelocations were finalizedin the field to accommodate the pier spacing to achieve the optimumheating configuration. A five foot gap between the bottom of floor slaband grade provided additional challenges for drilling and electrode place-ment. Eighteen by eighteen inch squares were cut in the slab to accom-modate electrodes (Figure 3).

ResultsPrior to SPH, the average concentration of total SA’s in groundwater was55,934 µg/l. Following SPH, the final average total SA’s concentration was1,158 µg/l. The SPH remediation reduced average total concentrations by98%. All post heating sampling has shown the SA concentrations insidethe treatment area have remained below the 10,000 µg/l goal.

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Guaranteed Fixed Price Remediation of DNAPL and LNAPL using ERH — Fort Lewis Superfund SiteFort Lewis, Washington

TRS would like to acknowledge the following in the development in this poster: CH2M Hill, ShawEnvironmental, Tetra Tech, URS, U.S. Army Corps of Engineers, and U.S. EPA. Accelerating Value

Figure 2. Concrete Piers

Figure 2. Groundwater Results Figure 3. Soil Results

Figure 3. Slab cuts for electrodes

Figure 1. NAPL Areas 1, 2, 3

Figure 2. TCE in each NAPL area and averages pre- & post-ERH

Figure 1. Site Plan

Figure 1. Site Plan

Figure 1. Site View

Figure 2. PCE Concentrations pre- & post- ERH

Figure 1. PCE source area.

Figure 2 and 3. PCE concentrations

Figure 2 (top). Benzene concentrations in groundwater pre- & post- ERH

Figure 3 (bottom). Total BTEX concentrations in groundwater pre- & post- ERH

Figure 1. Site View

Figure 2. Average total CVOC concentrations (µg/kg) in soil with depth before andafter ERH

For more information please contact:David Fleming, Vice President of Marketing and Sales(425) 396-4266, dfleming@thermalrs.comwww.thermalrs.com

Figure 1. Site Plan