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

Revised CharacterizationPlan AcceleratesPetroleum BrownfieldCleanup andRedevelopment page 1

ERI Survey HelpsDelineate TCE Plumeand Guide FieldTesting of InnovativeISCO CandleTechnology page 3

3D-CSIA Forensicsat the FAMU LawSchool Site RevealsMultiple ContaminantSources page 4

NEWS TRENDSMarch 2011Issue 52

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Contents

CLU-IN Resources

Extensive information aboutcontaminated site character-ization and monitoring isavailable on the U.S. Environ-mental Protection Agency’s(EPA’s) CLU-IN web host.Topics currently include typicaluses, components, operationalmodes, performance specifica-tions, and verification reportson 20 analytical, direct-push,and geophysical tools. Learnmore at: www.cluin.org/characterization/.

Revised Characterization Plan Accelerates PetroleumBrownfield Cleanup and Redevelopment

This issue of Technology News and Trends highlights techniques to enhance site investigationsthrough advanced data integration and high resolution technology such as membrane interfaceprobes, electrical resistivity imagery, and compound specific isotope analysis. In addition toimproving the conceptual site model, use of these field and laboratory tools can aid in theselection of innovative design, construction, and monitoring approaches facilitating increaseduse of in situ cleanup remedies.

Efforts to better delineate contaminationand accelerate remediation of the formerFannon Petroleum Services site inAlexandria, VA, were initiated in the early2000s as part of a plan to redevelop the sitefor residential use. Strategically locatednear the Potomac River in “Old Town”Alexandria, the site had been used as a fueldepot since the 1880s. Discovery of up to40 inches of petroleum product inmonitoring wells near the site in the early1980s prompted a preliminary siteinvestigation and recovery of oil. Continuedhigh concentrations of dissolvedcontaminants, slow rates of oil recovery, andthe property’s high potential forredevelopment collectively prompted aneffort to better define the nature and extent ofcontamination, identify all areas needingremediation, and characterize the riskassociated with remaining contamination.Project success is attributed to combinedefforts of the property owner, the VirginiaDepartment of Environmental Quality (VADEQ), and the City to address the site’senvironmental and economic issues.

Historical records suggest that 50,000 gallonsof fuel could have been released since 1962due to poor procedures for handling andstoring materials such as gasoline, diesel,kerosene, ethanol, and methanol. When thepetroleum product was discovered by utilitymaintenance crews working at neighboring

properties in 1982, the high volume of fuelsuggested that the utility work had rupturedan underground fuel line. After several yearsof oil recovery by the site owner, groundwatermonitoring in the early 1990s identified a free-phase plume extending from the undergroundstorage tank (UST) and loading rack area. Bythe late 1990s, monitoring indicated that thecontaminant plume had migrated to offsiteproperties as far as 300 feet from thesuspected source area. An onsitegroundwater pump-and-treat (P&T) systemand soil vapor extraction system beganoperating in 2001 to treat subsurface areastargeted through investigations relying onconventional sampling techniques.Groundwater was extracted for treatment at arate of approximately 6 gal/hr.

As part of the plan for improved sitecharacterization and accelerated cleanup, theVA DEQ initiated the Triad approach. Projectplanning included development of aconceptual site model and consensus onspecific investigative methods and tools, witha focus on using: (1) a membrane interfaceprobe (MIP) to characterize distribution ofvolatile organic compounds (VOCs) indiscrete hydrologic units and soilstratigraphy at offsite locations; (2) direct-sensing geophysical tools rather thangroundwater and soil sampling for initialscreening; and (3) a dynamic work strategy to

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allow real-time decision making that couldidentify specific locations for direct-sensinglocations as work proceeded. Onsite areasof contaminated material were delineated forexcavation and offsite disposal during theanticipated residential construction.

In early 2006, MIP data mapping beganon the properties and streets adjacent toand downgradient of the fuel depot. Theuse of MIP technology at Fannoninvolved a portable controller and a direct-push rig to advance a probe into thesubsurface for the purpose of heating thesoil, water, and vapor matrix. The heatedVOCs were drawn across a permeablemembrane near the tip of the probe andcarried by an inert purge gas throughsmall-diameter tubing connected to asensor detection system at groundsurface. The detection system consistedof three direct-sensing tools: aphotoionization detector (PID), a flameionization detector (FID), and an electroncapture detector. Along with a portablegas chromatograph for periodicconfirmatory analysis, these detectorshelped delineate subsurface zones ofpetroleum product and specific types ofVOCs. All detection, analytical, andcontrol equipment was transported in astandard utility vehicle traveling a few feetin front of the direct-push rig (Figure 1).

An average of five probes were advanceddaily, each resulting in a continuous,vertical 30- to 40-foot profile of thesubsurface with more than 20 data pointsper foot. Chemical and geological datafrom each profile included VOCconcentrations identified through PID andFID, soil conductivity, and temperaturemeasurements. Electronic displays of theprofiles and associated three-dimensional(3-D) maps were viewed in the field by theVA DEQ, the site owner’s environmentalconsultant, City staff, and otherstakeholders for better-informed andfaster decisions. MIP data were collectedthrough a total of 44 probes during a

single mobilization spanning two weeks. Thesurvey was terminated once the VA DEQ andenvironmental consultant agreed on theextent and severity of the offsite plume.

The MIP results generally correlated withthe plume defined by earlier, conventionalmethods but identified a previouslyunknown offsite lobe of contamination.Conceptual model refinement indicated a 60-by 120-foot plume at a depth of 15 feet belowground surface (bgs). High resolutionmapping of the lobe suggested that the free-phase plume intersected and then migratedalong the municipal sanitary/storm sewersystem. This area of contamination, whichyears of conventional investigation hadfailed to identify, accounted for thesignificant offsite contamination discoveredduring the 1982 utility work. Overall resultsindicated that removal of the source areaduring residential construction shouldprevent further plume migration. MIPmapping also led to identification of analternate location for the remedial system ona downgradient adjacent property.

Twenty-eight USTs, underground piping,the terminal loading rack, andapproximately 35,000 tons of petroleum-contaminated soil subsequently wereexcavated and removed from the sourcearea. The remedial system was concurrentlytransferred to its new location, and severalnew extraction wells were installed tosupplement existing offsite recovery wells.

Costs for MIP deployment and onsitedetection and analysis equipment forseveral weeks of field work totaledapproximately $55,000. In contrast, earliersite characterizations through conventionalmethods in conjunction with many soil andgroundwater sample analyses had costhundreds of thousands of dollars andnumerous mobilizations over multiple years.

Conventional sample analysis nowindicates that the P&T system ishydraulically controlling the contaminantplume and reducing the remaining free-phase fuel oil and dissolved-phasegroundwater contaminants. The systemwill continue operating until the VADEQ-approved risk-based cleanupgoals are met.

To date, the P&T systems have treatedover 6 million gallons of petroleum-contaminated groundwater and removedover 4,200 pounds of total petroleumhydrocarbons, 350 pounds of benzene,toluene, ethene, and xylenes (BTEX), 78pounds of methyl-tertiary-butyl ether(MTBE), and 15 pounds of naphthalene.An estimated 5,000 gallons of fuel oil havebeen recovered, and nearly 7,000 poundsof subsurface petroleum vapors havebeen removed.

Remedial actions specified in theredevelopment plans (per the city’scontaminated land program) included avapor intrusion abatement systemcomprising an upgraded vapor barrier,active sub-slab ventilation, and a treatmentunit for groundwater drainage to eliminateany potential risks of exposure from thedevelopment. Use of MIP also enabledstakeholders to revise the site’sconstruction plan to include a depth

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Figure 1. MIP deployment for plumedelineation near the former FannonPetroleum Services site could be completedat each location in less than one hour, withlittle disruption to ongoing activities.

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ERI Survey Helps Delineate TCE Plume and Guide Field Testing of Innovative ISCO Candle Technology

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EPA partnered with the New York City Office of Environmental Remediation to compilethe report, Streamlining Site Cleanup in New York City (EPA 542-R-10-005). Thereport presents a plan for using the Triad approach and associated best practives tocharacterize sites and optimize remediation of low to moderately contaminated landwhile addressing a municipal need to sustainably develop commercial, residential, andrecreational properties. Use of Triad in the New York metropolitan area has shown significantadvantages for brownfields redevelopment programs, including those involving old fillareas and waterfront property. Access the report from EPA’s Brownfields and LandRevitalization Technology Support Center at: www.brownfieldstsc.org/.

More About Accelerating Urban Brownfield Cleanuprestriction for anticipated structures.Residential construction began in 2008and was completed in 2010.

Contributed by Randy Chapman, VADEQ (randy.chapman@deq.virginia.govor 703-583-3816) and Daniel Imig, Cityof Alexandria Office of EnvironmentalQuality (daniel.imig@alexandriava.govor 703-746-4070)

A 1989 investigation by the NebraskaDepartment of Environmental Quality(NDEQ) found a high concentration (37,000μg/L) of trichloroethene (TCE) and otherVOCs in shallow groundwater near a closedcell of a former municipal landfill in Cozad,NE. Using funds from an NDEQ landfillclosure grant, the City conducted numeroussite investigations and installed severalremedial measures. By 2008, however, annualgroundwater monitoring indicated that theaverage TCE concentration in groundwaterremained elevated at 688 ug/L. With NDEQ’sand the City’s concurrence, the Universityof Nebraska-Lincoln (UNL) began an effortin 2009 to investigate new tools forsubsurface characterization and field test analternative remedial technology. Projectfunding was provided to UNL by the U.S.Congress and administered by EPA througha cooperative agreement.

The City of Cozad had owned and operatedthe landfill until 1987, when the facility wasclosed due to noncompliance with the State’snew regulations on small municipal landfills.The site’s unlined 400- by 40-foot waste cellextends 20 feet bgs and is capped with a thinlayer of clay soil. Approximately 5 feet ofsilty clay separates the bottom of the cellfrom 35 feet of alluvial sand, which overliesthe Ogallala member of the High PlainsAquifer. The City’s early site investigationincluded installing 19 groundwatermonitoring wells to depths of 8-170 feet bgs.As of 2008, groundwater modeling estimateda VOC plume about 600 feet long, 125 feetwide, and 20 feet deep. Limited success of

the remedial attempts, which included a dual-phase extraction well system, poplar trees toinduce phytoremediation, and severalvolatilization ponds, was attributed to lowpermeability of the aquifer and insufficientcharacterization of the contaminant plume.

The subsequent UNL investigation usedelectrical resistivity imaging (ERI) tocharacterize the closed cell area. Grid andboundary lines of the survey were based onhistorical TCE groundwater concentrations,proximity of the highest TCE concentrationsto a targeted (east) portion of the cell, existingpoplars and evaporation ponds, and propertylines representing legal points of compliance.Over three days in September 2009, images atmore than 7,100 data points were collectedalong 22 survey lines.

ERI results identified three distinctconductivity layers in the substrata, whichcorresponded to differences in lithology andhydraulic conductivities. The ERI maps wereused to guide groundwater sampling via directpush technology. Soil and groundwatersamples were collected from depths of 5-69feet bgs at 64 locations. Results of this focusedsampling effort indicated that the vast majorityof contamination was contained in a layer oflow-permeability loess near the water table,within 20 feet of the ground surface. Not all ofthe loess was found to be contaminated, butessentially all of the contamination was locatedin this low permeability layer.

With technical assistance from UNL, the ERIsurvey was performed in part by Oklahoma

State University faculty at a discountedresearch-based cost of $9,000. Costs forgroundwater sample collection and analysis(completed primarily by UNL graduatestudents) totaled approximately $17,000.When compared to commercial projects,NDEQ estimates a significant savings in fieldand analytical labor expenses attributable tothe project’s academic partners.

Improved understanding of the site’sremedial progress and current extent ofcontamination enabled project partners toexplore lower-cost remedial technologies,particularly in situ chemical oxidation (ISCO).Conventional ISCO by injecting liquidoxidants into groundwater was anticipatedto be unsuccessful, due to the low aquiferconductivity within the target area. Instead,slow-release potassium permanganatecandles (SRPCs) were selected for use on apilot-scale basis. SRPCs consist of granularpotassium permanganate (KMnO4)embedded in a paraffin wax matrix. Earlierlaboratory SRPC studies by Ohio StateUniversity demonstrated that the KMnO4

slowly dissolves and diffuses through thewax matrix upon contact with water. TheMnO4

- can then react with chlorinatedsolvents such as TCE and reduce them toCO2 and Cl-.

UNL researchers developed an in-houseSRPC production process, conductedbench-scale tests to quantify the SRPCdissolution rates, and designed an SRPCsystem to be applied at the landfill.

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groundwater sampling shows no evidenceof impacts on the deeper Ogallala Aquifer.

Pilot study costs for the SRPC installationtotal approximately $18,000 to date; thisincludes $4,000 for chemicals and $14,000for installing the monitoring wells and SRPCwells and renting direct push equipment.Pending SRPC efficacy in meeting the State’sgroundwater protection standard for TCE(below 5 μg/L), NDEQ anticipates the Citywill oversee the SRPC system after UNLwork is complete. Future evaluation ofwhether changes can be made to the existingremediation systems also is anticipated, toreduce operation and maintenance costswhile still meeting the cleanup goals within20 years.

Contributed by Steve Comfort and MarkChristenson, UNL (scomfort@unl.edu or402-472-1502), Laurie Brunner, NDEQ(laurie.brunner@nebraska.gov or 402-471-2214), and Kenneth Rapplean, EPARegion 7 (rapplean.kenneth@epa.govor 913-551-7769)

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3D-CSIA Forensics at the FAMU Law School Site Reveals Multiple Contaminant Sources

The Florida Department of EnvironmentalProtection (FL DEP) recently conducteda 3-D compound-specific isotopeanalysis (3D-CSIA) investigation at theFlorida Agricultural and MechanicalUniversity (FAMU) Law School site indowntown Orlando. This 3D-CSIA wasundertaken as part of a multiple lines ofevidence approach to determine potentialsources of groundwater contamination.Previous FAMU-sponsored groundwaterinvestigations identified widespreadchlorinated hydrocarbons at concentrationsexceeding Florida Primary Drinking WaterStandards (FPDWS). To better understandpotential sources of these contaminants,the FL DEP examined isotope ratios of the

three elements (13C/12C, 37Cl/35Cl, and 2H/1H)in the primary contaminants of concern,tetrachloroethene (PCE), TCE, and cis-1,2-dichloroethene (cDCE).

Since the isotopic ratios of PCE and TCE varydepending on the manufacturer, 3D-CSIA canbe used to help differentiate sources of thechlorinated solvents and determine thesequence of multiple releases based on a site’spast PCE, TCE, and cDCE usage. Thetechnique also can help identify, characterize,and quantify biotic and abiotic transformationreactions because both biotic and abioticdegradation processes are associated withsignificant isotopic fractionation. Results ofisotope analyses are generally reported as δ

values, e.g., δ13C for carbon, δ37Cl for chlorine,and δ2H for hydrogen. The δ symbolrepresents a comparison between the ratiosof the different stable isotopes of anelement, such as 13C to 12C, 37Cl to 35Cl, and2H to 1H, and is expressed in parts perthousand (‰) of an internationallyaccepted standard reference concentration.A δ13C of -30‰, for example, indicates thatthe ratio of 13C to 12C in the sample is 3%lower than the standard. A more negative δvalue indicates that a chemical is depletedin the heavier isotope (13C, 37Cl, or 2H).Biodegradation agents preferentially breakdown the lighter isotopes of differentelements, inducing a shift of the residual

Treatability study results (using core samplescollected from the site) indicated KMnO4

breakthrough across 1.74 cm of soil occurredwithin 24 hours for most samples. Laboratoryperformance of miniature SRPCs predicted alifespan of 7.5 and 16.5 years, respectively,for two- and three-inch-diameter SRPCs,based on a predicted MNO4

release rate of 3grams/day in each treatment well. Additionaltrials at UNL included testing the potentialexplosion hazard of a full-scale 3-inch candle.Failure to explode during cap blastingsupported earlier laboratory findings that thepresence of paraffin wax avoids the explosionrisk posed by dry permanganate.

With technical oversight from NDEQ, a totalof 50 three-inch and 105 two-inch SRPCs wereinstalled in July 2010; each SRPC was threefeet long. The three-inch SRPCs were insertedinto tailored containers and placed inside 4-inch-diameter wells installed using directpush technology on 4-foot centers to a depthof 22 feet (Figure 2). The two-inch SRPCswere placed directly into the aquifer at 5-footincrements through use of hollow direct-pushrods (on 2-foot centers) reaching 22 feet bgs.Collectively, the candles containedapproximately 1,400 pounds of KMnO4 and300 pounds of paraffin. Upon oxidantdiffusion, the emplaced materials would

essentially create a 20-foot-wide permeablereactive barrier intersecting the plume portionwith highest TCE concentrations.

Groundwater sampling conducted 85 daysafter SRPC installation indicated an 80-85%reduction of total VOC concentrations intreatment zone monitoring wells. Samplingresults from one shallow well within thetreatment zone, for example, exhibited a TCEconcentration approaching 400 μg/L prior toSRPC installation and a post-treatment TCEconcentration of approximately 75 μg/L.Detection of MnO4

- in a deeper well indicateddiffusion of the slow-releasing oxidant hadstarted to occur, which supported predictionthat uniform KMnO4 distribution throughoutthe target subsurface area could occur in 6-12months after installation. Currently, the TCEconcentration in the downgradient point ofcompliance well is slightly below the 5 μg/Lfederal maximum contaminant level (MCL), and

Figure 2. As part of ISCO implementationat the former Cozad landfill, five 3-footKMnO4/paraffin candles were verticallystacked in a slotted holder and loweredinto each of ten groundwater wells.

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compound to a less negative δ 13C value. Amore negative δ13C value would suggest acloser source and more recent release of achemical into the environment.

The target investigation area at theFAMU Law School encompassesapproximately eight city blocks thatinclude various businesses andresidential complexes. The site isunderlain by about 50 feet of fine- tomedium-grain sand with increasing siltand clay with depth. The average depthto the water table is 11 feet bgs. Nearly alldeep groundwater samples collected atthe site were found to contain detectablelevels of chlorinated hydrocarbons, with

many exceeding FPDWS. The highest PCE,TCE, and cDCE concentrations (Table 1)were detected in three monitoring wellslocated near a former uniform rental servicein the northwestern corner of the study area(Figure 3). Based on past and currentproperty uses, other potential sources ofPCE, TCE, and cDCE in the target areainclude former dry cleaners, print shops,and automobile repair shops.

During the winter of 2009, groundwatersamples from seven wells at the FAMU sitewere analyzed for both the presence ofchlorinated VOCs and their isotope ratios.A gas chromatograph coupled with anisotope-ratio mass spectrometer was usedto determine the isotope ratios for chlorinated

VOCs detected at concentrations greaterthan 10 parts per billion (ppb).

Techniques for collecting and preservinggroundwater samples for 3D-CSIA areidentical to those for VOC analysis usingEPA Method 8620B. In this investigation,all samples were collected usingstandardized techniques and then shippedto an offsite laboratory. The average costfor each set of 3D isotopic signatures ofcDCE, TCE, and PCE was $900.

The highest concentrations of PCE(1,700-24,000 ppb) were detected in thethree wells near the former uniformrental service (Table 1). The PCE in thewells have similar δ13C and δ37Cl ratios,indicating a major release of PCE from asingle source. The δ13C measured in TCEat MW-1A is indicative of amanufactured TCE; the significantlydifferent δ37Cl and the very high δ2H alsosupport a manufactured source of TCEin this well . However, the ratiosmeasured for TCE in MW-1D indicatesome biodegradation of PCE isoccurring. The lighter δ13C, similar δ37Cl,and low δ2H suggest biodegradation.

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Figure 3. Seven wells near multiplepotential chlorinated solvent sourceswere sampled for 3D-CSIA at the FAMULaw School site.

Table 1. The isotopic ratios of PCE, TCE, and cDCE detected in the wells at the FAMU site suggest multiple releases ofPCE and TCE that are both a result of direct release as well as degradation of PCE.

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NEWS TRENDS

TechnologyTechnologyTechnologyTechnologyTechnologyand

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EPA’s Office of Solid Waste andEmergency Response recentlyissued Best Management Prac-tices: Use of Systematic ProjectPlanning Under a Triad Approachfor Site Assessment and Cleanup(EPA 542-F-10-010). Topics includeuse of a conceptual site model andsamples of successful systematicproject planning. Access thebulletin at: www.brownfieldstsc.org/.

New Technical Bulletin

The cDCE in both wells appears to havea manufactured origin.

Wells IS-50' and DEP-9D are located evenfurther downgradient of the former drycleaner, but have higher concentrations ofTCE than PCE. The δ13C and δ37Cl ratios forPCE in these wells are heavier than for TCE,suggesting TCE is primarily a product biotictransformation. However, the 128‰ δ2Hin IS-50' indicates the manufactured TCEmay be commingled with a small amountof TCE that has degraded from PCE.

Wells DEP-19D and DEP-14D, locateddowngradient of a former dry cleaner at thesouth edge of the site, had similar δ13C ratiosfor PCE but slightly different δ37Cl ratios.Both matched ratios for manufactured PCE,potentially indicating the potential useand release of different PCE formulationsat the former dry cleaner (Table 1).

Costs for 3D-CSIA planning, laboratoryanalysis, and data interpretation at the

FAMU site totaled approximately $9,500.Using this approach, the FL DEP was ableto confirm two hydrocarbon releasesources, as indicated by earlier groundwatersampling, at the FAMU site. Overall 3D-CSIA results indicate that the former drycleaner and former uniform rental servicewere the main contributors to groundwatercontamination. Isotopic data from wells IS-50' and DEP-9D, however, suggest otheras of yet unidentified sources ofchlorinated hydrocarbons. The FL DEP isplanning remediation of the site as effortsto delineate other contaminant sourcescontinues, and anticipates using results ofthis study as background information forfuture FL DEP investigations.

Contributed by Jeff Newton, FloridaDEP (Jeff.Newton@dep.state.fl.us or850-245-8955), Amber Igoe, TetraTech(Amber.Igoe@tetratech.com or850-385-9866), and Yi Wang, Ph.D.,DPRA-ZymaX Forensics IsotopeLaboratory (Yi.Wang@zymaxusa.com or760-781-3338 ext. 43)