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A newsletter about soil, sediment, and groundwater characterization and remediation technologies

PRB Expanded toFull-Scale Operationfor AcceleratingTreatment ofMetals page 1

Four-YearMonitoring ShowsSource-Area VOCReductions AfterERH/SVE at NavalStation-Annapolis page 3

Nearly Five Yearsof SER ApproachesFull Treatment ofSource Areas atPort of Ridgefield page 4

Update on EPARemedialOptimizationStudies page 6

NEWS TRENDSJune 2010Issue 48

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Contents

CLU-IN Resources

The new Sedimentscontaminant focus area ofCLU-IN provides policy andguidance, describes con-ceptual site models, anddiscusses the uniqueaspects of characterizingand remediating contami-nated sediment. Learnmore at: www.clu-in.org/contaminantfocus.

This issue of Technology News and Trends provides selected updates on innova-tive technology applications described in past issues. Some applications movedtoward full-scale implementation at previous study sites while others drew sitesmuch nearer to cleanup closure.

PRB Expanded to Full-Scale Operation forAccelerating Treatment of Metals

A five-year evaluation of a pilot-scale,sulfate-reducing permeable reactivebarrier (SR-PRB) installed at theStoller Chemical Site in Jericho, SC, in2004 recently led to installation andimplementation of a full-scale SR-PRB. [See the February 2006 issueof TNT for details on the pilot-scaleproject.] After completing an updatedfeasibility study and record of decision,the South Carolina Department ofHealth and Environmental Control(SCDHEC) installed the barrier withina two-month period in early 2009 tocontinue treating groundwater metalsof concern.

The SR-PRB was installed immediatelydowngradient of an onsite contaminantsource area, in the vicinity of agroundwater pump and treat (P&T)system that had operated on an interimbasis since 2002. In 2009, when P&Toperations were terminated and thesystem was dissembled to create spacefor the barrier, concentrations forcontaminants of concern (COCs) insource-area groundwater were 22 μg/Larsenic, 160 μg/L chromium, 0.25 mg/Lcadmium, 3.7 mg/L copper, 0.66 mg/Lnickel, 19 mg/L manganese, 25 mg/L zinc,250 mg/L aluminum, and 69 mg/L iron.

Project designs called for a continuousV-shaped SR-PRB approximately 380feet long, 12 feet wide, and 13 feetdeep. The barrier was keyed into an

underlying confining unit at a depth of13-23 feet below ground surface (bgs).The groundwater flow rate in this areais estimated at 0.36 ft/day.

SR-PRB construction involvedsequential framing, excavation, andfilling of 12 individual cells approximately32 feet long. Due to the occurrence offlowing sands, each cell wasconstructed by installing rigid sheetpiling along the sides of the trench andattaching the piling to a rectangularframe of 12-inch steel to prevent inwardcollapse. A conventional backhoe wasused to remove approximately 185 yd3

of soil from each braced cell and fillthe trench with sulfate-reducingamendments. The steel bracing wasthen moved to the next cell, where theprocess was repeated. Trench spoilswere placed in other areas of the sitefor reuse.

Selection of amendment materials wasbased on their capability to enhancegrowth of sulfate-reducing bacteria thatconvert soluble metallic sulfates toinsoluble metallic sulfides, therebyremoving the dissolved metals fromgroundwater. The selected amendmentmixture for each cell contained 38%wood chips, 32% hay and alfalfa, 17%sawdust with trace amounts of cementkiln dust, 7% limestone screenings, and6% cow manure.

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Figure 1.Amendmentplacement andmixing in eachcell achieved abarrier heightof 2.5-3.0 feetbgs.

The amendments were mixed directlywithin each excavated cell in threeseparate lifts (Figure 1). Any seepagewater and a few gallons ofgroundwater were added to themixture to facilitate mixing of eachlift. After the third lift was emplaced,approximately 100 gallons ofadditional contaminated groundwaterfrom an adjacent well were pumpedinto the cell.

The entrenched materials wereallowed to incubate until the oxidation-reduction potential reached -100 mVor lower, which typically required twoweeks. Following incubation, the sheetpiling was removed (Figure 2) to allowflow of contaminated groundwaterthrough the filled cell and for reuse inconstruction of the next cell. A finalcover comprising an impermeableliner topped by a 24-inch layer of soilwas then installed in each cell andgraded to prevent excessiveinfiltration by rainfall.

The completed SR-PRB contained atotal of 672.83 tons of amendmentsconsisting of 225.28 tons (900 yd3) ofwood chips, 67.27 tons of hay andalfalfa (3,372 bales), 111.05 tons of

sawdust (397 yd3), 6.73 tons ofcement kiln dust (10 yd3), 195.17 tons(174 yd3) of limestone, and 67.33 tons(133 yd3) of manure. By sequencingand overlapping construct ioncomponents for individual cells,construction of all 12 cells wascompleted over 60 days, one monthahead of schedule.

Detailed water quality monitoring inMarch 2010 (approximately one yearafter groundwater began flowingthrough the entire SR-PRB) indicatedthat water in all three downgradient

performance monitoring wellscontained COC concentrations belowthe maximum contaminant levels of0.01 ppm arsenic, 0.005 ppmcadmium, 0.1 ppm chromium, 0.1ppm nickel, and 1.3 ppm copper.Site-specific remedial goals foraluminum (16.9 ppm), manganese (5ppm), and zinc (5 ppm) set forth inthe revised record of decision weremet at al l three downgradientmonitoring points. The site-specificgoal of 10 ppm for iron was met intwo of the three monitoring points;at the third, iron concentrationsdecreased to 27 ppm.

SCDHEC estimates that the cost ofinstalling the PRB was equivalent tothe cost of approximately three yearsof the former P&T operations. Thesystem’s lifespan is estimated at 15years, without any need forreplenishment or replacement of thereactive media.

Two additional SR-PRBs are plannedfor the offsite residential area acrossthe street from the Stoller propertyto intercept the downgradient toe ofthe contaminated groundwaterplume and prevent discharge ofcontamination to the area’s

Figure 2. Anexcavatorequipped with avibrator hammerwas used to installand remove thesteel sheets alonglengths of theStoller ChemicalSR-PRB.

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Three-phase ERH technology wasimplemented at Site 1 by way of steamstripping and in situ hydrolysis toconvert TeCA to the more volatileTCE and subsequently remove theTCE. Integrated ERH/SVE systemcomponents included 24 steelelectrodes, a steam condenser, oneblower, and a granular-activated carbonfiltration (GAC) system. The subsurfacesoil was heated to temperaturesaveraging 99°C (210°F) over 116 days,from February to May 2006.

As anticipated, TCE concentrations inthe treatment-area groundwatermonitoring wells significantly increasedimmediately after ERH/SVE treatment,which indicated hydrolysis hadoccurred. Concentrations then droppedto below pre-treatment levels overfollowing months. For example, onetreatment-area monitoring well with aTCE concentration of 2,800 μg/L priorto treatment exhibited a concentrationof 27,000 μg/L five months later,followed by a concentration below 2,000

Four-Year Monitoring Shows Source-Area VOC Reductions After ERH/SVE at Naval Station-Annapolis

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The U.S. Navy applied electricalresistance heating (ERH) and soilvapor extraction (SVE) in 2006 asan interim action to remove 1,1,2,2-tetrachloroethane (TeCA) andtrichloroethene (TCE) from sourceareas at Site 1 of the Naval SupportActivity installation in Annapolis, MD(former Naval Station-Annapolis)[see September 2007 TNT]. Analysisof soil samples collected uponcomplete cooling of the subsurfacein January 2009 indicated anaverage 99.6% reduction in TeCAconcentrations and 99.9% reductionin TCE concentrations. Samplingresults since then show concentrationsin soil remain below the correspondingU.S. EPA industrial standards of2,900 μg/kg and 14,000 μg/kg. Ingroundwater of wells adjacent to thetreatment area, TeCA and TCEconcentrations have decreased anaverage 98% and 74%, respectively,as a result of ERH/SVE applicationin the source areas.

μg/L in subsequent monitoring events(Figure 3). The most recent datacollected during biannual sampling ofwells adjacent to the treatment areashow that TeCA and TCEconcentrations have decreased to anaverage of 35 μg/L and 475 μg/L,respectively.

Monitoring downgradient of the sourceareas indicates that a plume of TCEwas released to groundwater duringheating of the source areas. Four wellslocated 250-800 feet downgradientexhibited a peak average increase of2,060% in volatile organic compound(VOC) concentrations approximatelytwo years after system shutdown. Allfour wells exhibited a decline of TeCAand TCE concentrations after thesecond-year sampling event, whichsuggested that VOC mobilization wastemporary. One well approximately 250feet downgradient, for example,showed a 1,200% and 1,100% increasein TeCA and TCE, respectively, followedby notably lower concentrations sevenmonths later (Figure 4).

The Navy continues to monitor VOCsat Site 1 to evaluate groundwaterconcentration trends associated withthis interim action. Groundwatermonitoring costs since the 2006

wetlands. Modeling estimates thatthe maximum concentration ofcadmium (the primary offsite COC)

likely present as a residual solid withinthe anticipated barrier would notexceed the 70 mg/kg residentialscreening level for soil.

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Figure 3. TCE concentrations in onemonitoring well at the downgradientperimeter of the Site 1 treatment areadecreased to 940 μg/L within fouryears of ERH/SVE implementation,after an initial spike caused by rapidbreakdown of TeCA to TCE.

Contributed by Judy Canova,SCDHEC (canovajl@dhec.sc.govor 803-896-4046)

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Nearly Five Years of SER Approaches Full Treatment of Source Areas at Port of RidgefieldThe Port of Ridgefield (POR), WA,recently began the last phase ofs team-enhanced remedia t ion(SER) at the POR’s Lake RiverIndustrial Site (LRIS). Pilot-scaleSER was conducted in 2004 to treatsoil and groundwater contaminatedby wood-treating waste and toprevent nonaqueous-phase liquid(NAPL) f rom migra t ing in toenvironmentally sensitive areas.The first phase of full-scale operationwas initiated on one acre in 2006 withplans to sequentially remediate threeadditional 1-acre subareas by 2013-2015 [see September 2007 TNT].As of December 2009, SERimplementation had removedapproximately 23,900 gallons ofNAPL and fully treated approximately110 million gallons of groundwater forsurface water discharge.Approximately 465 tons of sludgehad also been generated through theliquid treatment system and disposedat an offsite hazardous waste landfill.

Remediation of the LRIS isenvironmentally sensitive due to itsproximity to the Ridgefield NationalWildlife Refuge (including CartyLake) and the City of Ridgefield as

well as its position on the banks ofLake River, a tributary of the ColumbiaRiver. The SER system has focusedon removing mobile contaminants inshallow groundwater within the 4-acreNAPL plume, above an aquitardapproximately 50 feet bgs.

Comparison of contaminant concentrationsin system influent collected during thefirst three months of treatment withinfluent data gathered in late 2009indicates significant contaminantreductions: greater than 99.4% forbenzene (originally 50 μg/L), 97.7%for pentachlorophenol (PCP)(originally 7,500 μg/L), 99.8% fornaphthalene (originally 18,000 μg/L),90.6% for tetrachloroethene(originally 30 μg/L), and 49% forarsenic (originally 80 μg/L). Inaddition, dissolved concentrations ofPCP (Figure 5) and all other COCs thatwere historically detected in the upperwater-bearing zone beneath CartyLake were no longer detected andplume migration toward Carty Lakeand the Lake River had halted.

Groundwater monitoring shows thatthe areal extent of light NAPL hasdecreased 90% from the original

estimate of four acres, with noonsite indication of dense NAPL.Approximately 85% of this removalrate is achieved through the onsitevapor treatment system, whichincludes a heat exchanger, air/liquidseparators, air dryers, and twosteam-regenerated GAC units. Theremaining 15% of NAPL is removedthrough the liquid treatment systemconsist ing of another heatexchanger, oil/water separators,coagulation/flocculation units, aninclined clarifier, mixed-mediafiltration, and GAC filters.

POR personnel continue to monitorsubsurface temperatures and heatexpansion through use of real-timedata collection equipment such asdigital thermocouples. The rate ofsteam injection at each activeinjection well is modified as neededto maintain consistent heatingacross the entire treatment zone.Temperatures of treatment systeminfluent have averaged 135°F.During active treatment, whichaverages 180 days for each 1-acreSER phase, a minimum of two staff

shutdown have averaged less than$20,000/year.

Contributed by Ryan Mayer, U.S.Navy (ryan.mayer@navy.mil or202-685-3282) and StevenKawchak, Shaw Group(sgkawchak@shawgrp.com or609-588-6349)

Figure 4. With an an estimatedgroundwater flow rate below 1 ft/day,impacts from Site 1 source-areaERH/SVE implementation were observedat one well approximately 21 months later.

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Figure 5. Three-dimensional kriging models illustrate PCPconcentration reductions of approximately two orders of magnitudein groundwater at the Port of Ridgefield treatment area, primarilyin the shallow water-bearing zone above the aquitard.

members monitor the system 24hours per day, seven days per week.

SER implementation difficulties overthe four years of operation havestemmed primarily from the hightemperatures needed to operate thesystem and the corrosive nature ofthe heated chemicals. Electricalmeters, groundwater pumps, andrelease valves have been subject tofrequent maintenance andsometimes degraded in as little asseveral hours. In part icular,frequent breakdown of mechanicalpumps led to their replacement byfield-modified airlift pumps withfew moving parts.

Operational costs have averagedapproximately $400,000 per month.Of this, approximately 40% can be

attributed to natural gas that isconsumed at an average rate of 4,900therms per day. To control the energycosts, the POR established a goal ofheat energy input of 500 kWh foreach cubic meter of soil across thetreatment area.

Concentrations of total contaminantsin groundwater inf luent haveaveraged 7 .5 mg/L s ince 2004star tup . Based on th is ef f luentconcentration, the POR estimatesthat the amount of contaminantremoved through SER over fouryears was equivalent to the amountpotentially removed by exclusive useof a P&T system over 140 years.The POR plans to operate the SERsystem through June 2011, when allmobile NAPL is expected to beremoved f rom the source area .Potent ia l r i sk associa ted wi th

residual, non-mobile contaminationin the treatment zone is currentlyunder assessment.

Contributed by Brent Grening,Port of Ridgefield(bgrening@portridgefield.orgor 360-887-3873) and AlanHughes, Maul Foster & Alongi,Inc. (ahughes@maulfoster.com or360-433-0217)

6EPA is publishing this newsletter as a means of disseminating useful information regarding innovative and alternative characterization or treatmenttechniques and technologies. The Agency does not endorse specific technology vendors.

Presorted StandardPostage and Fees PaidEPAPermit No. G-35

Solid Waste and EPA 542-N-10-003Emergency Response June 2010(5203P) Issue No. 48

United StatesEnvironmental Protection AgencyNational Service Center for Environmental PublicationsP.O. Box 42419Cincinnati, OH 45242

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Technology News and Trendsis on the NET! View, download,subscribe, and unsubscribe at:

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Contributions may be submitted to:

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and Technology InnovationU.S. Environmental Protection Agency

Phone: 703-603-7198quander.john@epa.gov

Contact UsUpdate on EPA Remedial Optimization Studies

The National Ground WaterAssociation will hold a three-daycourse on Understanding Migration,Assessment, and Remediationof Non-Aqueous Phase Liquids, onAugust 2-4, 2010, in Boston, MA.For more information about thisshort course, visit the NGWA at:www.ngwa.org/development.

NGWA Offers NAPL Training

The U.S. EPA’s Office of Superfund Remediation and Technology Innovationcompleted three additional remediation system evaluations (RSEs) this yearas part of an ongoing initiative to optimize P&T and other remedial systemsfinanced and managed by Superfund authorities and participating states. Therecent RSEs were conducted at the:

10th Street Superfund Site, Operable Unit 2, in Columbus, NEAlaric, Inc. Superfund Site in Tampa, FL, andMillcreek Dump Superfund Site in Erie County, PA.

Each RSE report provides recommendations on P&T protectiveness, cost-effectiveness, and potential technical improvements, and outlines options forgaining site closure and improving sustainability of long-term applications.Recommendations often involve system modifications to accommodate siteconditions that have changed over time, such as:

Removing or adding equipment or processes to a treatment trainReducing sampling frequency or the numbers of samples collected for long-

term monitoring, andIdentifying the need for additional study of secondary issues such as vapor

intrusion into onsite or offsite buildings.

To view final reports on RSEs conducted at 45 Superfund sites to date, as well asadditional evaluations completed under regional pilot programs and at RCRA sites(including those addressing underground storage tanks), visit: www.clu-in.org/RSE.