Pilot-scale evaluation using bioaugmentation to enhance PCE dissolution at dover AFB national test site

REMEDIATION Spring 2007

Pilot-Scale Evaluation UsingBioaugmentation to Enhance PCEDissolution at Dover AFB NationalTest Site

Carmen A. Lebron

Timothy McHale

Robroy Young

Dale Williams

Matthew G. Bogaart

David W. Major

Michaye L. McMaster

Ian Tasker

Naji Akladiss

An Interstate Technology and Regulatory Council (ITRC) forum was recently held that focused on six

case studies in which bioremediation of dense nonaqueous-phase liquids (DNAPLs) was performed;

the objective was to demonstrate that there is credible evidence for bioremediation as a viable envi-

ronmental remediation technology. The first two case studies from the forum have been previously

published; this third case study involves a pilot-scale demonstration that investigated the effects

of biological activity on enhancing dissolution of an emplaced tetrachloroethene (PCE) DNAPL

source. It used a controlled-release test cell with PCE as the primary DNAPL in a porous media

groundwater system. Both laboratory tests and a field-scale pilot test demonstrated that bioaug-

mentation can stimulate complete dechlorination to a nontoxic end product and that the mass

flux from a source zone increases when biological dehalorespiration activity is enhanced through

nutrient (electron donor) addition and bioaugmentation. All project goals were met. Important

achievements include demonstrating the ability to degrade a PCE DNAPL source to ethene and

obtaining significant information on the impacts to the microbial populations and corresponding

isotope enrichments during biodegradation of a source area. Oc 2007 Wiley Periodicals, Inc.

INTRODUCTION

This is the third in a series of articles on discussions held at an Interstate Technology andRegulatory Council (ITRC) forum that focused on case study projects in whichbioremediation of dense nonaqueous-phase liquids (DNAPLs) was performed. TheITRC’s Bioremediation of DNAPLs (BioDNAPL) Team hosted the forum in Long Beach,California, on March 28 and 29, 2006. The ITRC is a coalition of 46 states and the Districtof Columbia that works with federal agencies (primarily the U.S. Department of Energy[DOE], the U.S. Department of Defense [DOD], and the U.S. Environmental ProtectionAgency [US EPA]), industry, and other stakeholders to achieve regulatory acceptance ofenvironmental technologies. The BioDNAPL Team, one of 15 ITRC technical teams,aims to develop the technical and regulatory requirements for the bioremediation ofDNAPLs, with an emphasis on DNAPLs associated with chlorinated ethenes. The LongBeach Case Studies Forum is part of the BioDNAPL Team’s approach of using case studies

c© 2007 Wiley Periodicals, Inc.Published online in Wiley Interscience (www.interscience.wiley.com). DOI: 10.1002/rem.20121 5

Pilot-Scale Evaluation Using Bioaugmentation to Enhance PCE Dissolution at Dover AFB National Test Site

as a tool to clearly demonstrate the existence of well-established and credible evidence forbioremediation as a viable environmental remediation technology. The BioDNAPL Teamis currently working on a Long Beach Case Studies Forum proceedings document, atechnical and regulatory guidance document, and a Web-based resource guide onbioremediation of DNAPLs. For further details of the ITRC and the BioDNAPL Team,the reader is referred to the first and second articles in this series (Wymore et al., 2006;Payne et al., 2006).

This project was a pilot-scale demonstration completed to validate the effects ofbiological activity on enhancing dissolution of an emplaced PCE DNAPL source. The fielddemonstration was conducted at the Dover National Test Site (DNTS) in Dover,Delaware, which has five hydraulically contained sheet pile cells. In July 2001, a group ofresearchers from the University of Wyoming (UW) and Oregon State University (OSU)released 100 liters of PCE as a DNAPL into the vadose zone and the saturated zone (50liters to each area) of Test Cell #1 (Test Cell) at the DNTS. The UW and OSU researchfocused on noninvasive techniques to map DNAPL source zones but did not attempt toremove mass from the Test Cell. DOD, through the Environmental Security Technology

This project was a pilot-scale demonstration com-pleted to validate the ef-fects of biological activityon enhancing dissolution ofan emplaced PCE DNAPLsource.

Certification Program, funded the Naval Facilities Engineering Service Center (NFESC)and its contractor, GeoSyntec Consultants, to conduct a bioaugmentation demonstrationusing the PCE released in the Test Cell. During the demonstration, the Test Cell wasflushed at a constant groundwater velocity, and a number of test phases evaluated the rateof DNAPL removal and the extent of VOC treatment. Each phase was operated forsufficient duration to establish a near “steady-state” rate of DNAPL removal under each ofthe different operating conditions (i.e., under enhanced extraction conditions, underbiostimulation with sodium lactate and ethanol conditions, and under biostimulation plusbioaugmentation conditions).

The study approach consisted of laboratory tests and a field-scale pilot test todemonstrate that bioaugmentation can stimulate complete dechlorination to a nontoxicend product and that the mass flux from a source zone increases when biologicaldehalorespiration activity is enhanced through nutrient (electron donor) addition andbioaugmentation. The results of the laboratory experiments have been published andsummarized by others (Sleep et al., 2006). The focus of this case study is to present datafrom the field-scale pilot test.

SITE BACKGROUND

The study was conducted at the DNTS (formerly known as the Groundwater RemediationField Laboratory National Test Site, or GRFL NTS) in Dover, Delaware, in acontrolled-release Test Cell located at the DNTS. Dover Air Force Base (DAFB;Exhibit 1) is located three miles southeast of Dover, Delaware.

Site Conceptual Model

The DNTS is located within DAFB and was designed to support the needs of researchersdeveloping and demonstrating technologies for the cleanup of soil and groundwatercontaminated with fuels and solvents. The DNTS was located at DAFB because of thehydrogeologic environment combined with a history of innovative technologydemonstrations and a favorable regulatory climate. The DNTS covers approximately 3.5

6 Remediation DOI: 10.1002.rem c© 2007 Wiley Periodicals, Inc.

https://www.researchgate.net/publication/230166131_Enhanced_reductive_dechlorination_of_PCE_in_unconsolidated_soils?el=1_x_8&enrichId=rgreq-48615fe1-4281-4ab7-bfa1-302b8138558d&enrichSource=Y292ZXJQYWdlOzIzMDAyMDU0NjtBUzoyNDY3ODI0MTYzODgwOTdAMTQzNTg0ODkyMTE0NA==


Exhibit 1. Location of test cell at Dover National Test Site

acres in an unused, maintained open area in the northwest corner of the base. The St.Jones River and residential housing are located off-base to the west of the site. Directlyeast of the site is a soccer field and running track. To the north is the Dover AFBboundary, and to the south is an open field with an electrical transformer station. Since

c© 2007 Wiley Periodicals, Inc. Remediation DOI: 10.1002.rem 7


the primary focus of the DNTS is the demonstration of technologies to remediateDNAPLs, the DNTS maintains the capabilities (i.e., has a valid permit) to conductcontained releases of DNAPLs into the water table aquifer. A plan and cross-section viewof the Test Cell is presented in Exhibit 2.

DAFB is generally level with little topographic relief, with surface elevation rangingfrom 10 to 35 feet above mean sea level. The area has a continental type of climate that ismarked by well-defined seasons. January is the coldest month, with an average daily highof 42.5◦F and an average daily low of 25.3◦F. July is the warmest month, with an averagedaily high of 88.9◦F and an average daily low of 68.0◦F. Average annual rainfall is 44.37inches per year and is generally evenly distributed with May being the wettest month(5.16 inches) and October the driest (2.59 inches). DAFB is underlain by sediments ofCretaceous to present age, forming a wedge of sediments, which thickens to thesoutheast. The Pleistocene Columbia (1 million years ago, 1.0 Ma) and Lynch Heights(0.5 Ma) Formations form a water table aquifer in the area. Generally, these formationsare composed of medium to fine sands with gravely sand, silt, and clay lenses. The

The underlying Calvert For-mation is composed of ma-rine, estuarine, and deltaplain silty clays, and formsan aquitard to the uncon-fined Columbia Aquifer.

Columbia Formation is characterized by a fining-upward sequence of silty, poorly sortedsands. The Lynch Heights Formation overlies the Columbia Formation and is composed ofa coarsening upward sequence of silty sands. Discontinuous clay lenses are common in theLynch Heights Formation and occasional gravely sand lenses. Underlying the ColumbiaFormation is the upper unit of the Calvert Formation (Miocene). This unit generallyconsists of gray, firm, and dense marine clays with thin laminations of silt and fine sand.The thickness of this unit ranges from 20 to 28 feet beneath the base of the ColumbiaFormation. The Frederica Aquifer is a 22-foot-thick sand unit within the CalvertFormation. Beneath the upper sand unit is a middle silt and clay unit with a thickness ofgreater than 80 feet.

The primary water-bearing unit in the area of the DNTS is the Columbia Aquifer,which forms a water table aquifer overlying the Frederica, Cheswold, and Piney PointAquifers (confined aquifers). Analyses of water-level data collected during pumping testsconducted in the Columbia suggest that the hydraulic conductivity of the formation is inthe range of 3 × 10−3 to 1 × 10−2 cm/sec. Pumping tests conducted at DAFB suggest thatthe hydraulic conductivity of the unconfined Columbia Aquifer ranges from 2.8 × 10−3 to1.2 × 10−2 cm/sec. Groundwater from the Columbia Aquifer is generally soft, slightlyacidic, and characterized by low dissolved-solids content. High iron content and low pHare the only natural characteristics that commonly require treatment (Johnston, 1973).The underlying Calvert Formation is composed of marine, estuarine, and delta plain siltyclays, and forms an aquitard to the unconfined Columbia Aquifer. The aquitard thicknessranges between 18 and 28 feet (average of 22 feet). The estimated range of the verticalhydraulic conductivity of this unit is 2.7 × 10−8 to 1 × 10−7 cm/sec. Included in theCalvert Formation is the Frederica Aquifer, which is a thin, confined zone, composed offine sand that lays approximately 66 to 88 feet below ground surface (bgs). Regional watersupply aquifers in the DAFB area include the Piney Point, Cheswold, Frederica, andColumbia Aquifers. The top of the Cheswold Aquifer is approximately 175 feet bgs atDAFB and is separated from the Frederica Aquifer by approximately 87 feet of silty clay ofthe Calvert Formation. The top of the Piney Point Aquifer is approximately 334 feet bgsat DAFB and is separated from the Cheswold Aquifer by approximately 87 feet of siltyclay.


https://www.researchgate.net/publication/26992534_Hydrology_Of_The_Columbia_Pleistocene_Deposits_Of_Delaware_An_Appraisal_Of_A_Regional_Water-Table_Aquifer?el=1_x_8&enrichId=rgreq-48615fe1-4281-4ab7-bfa1-302b8138558d&enrichSource=Y292ZXJQYWdlOzIzMDAyMDU0NjtBUzoyNDY3ODI0MTYzODgwOTdAMTQzNTg0ODkyMTE0NA==


Exhibit 2. Plan and cross-section view of Test Cell 1



Exhibit 3. Summary of operating conditions and sample events

Remediation Goals

The primary objectives of the demonstration were:

� to enhance the dissolution rate (flux rate) of a DNAPL source via enhanced biologicalactivity (bioaugmentation);

� to demonstrate that enhanced biodegradation is an effective means of containing a highconcentration source zone by rapidly degrading the dissolved-phase plume emanatingfrom the source zone;

� to validate the performance of the technology at field scale; and� provide valuable operational data that may be used to guide future applications of this

technology.

As previously described, the test was operated in five phases. Exhibit 3 summarizesthe duration and composition of each phase. The details of each phase are discussed in theResults and Discussion section.

MATERIALS AND METHODS

Contaminant Distribution Within the Test Cell

Previous experiments at the Test Cell have included an in situ co-oxidation study ofchlorinated solvents during bioventing of petroleum hydrocarbons. The chemicals added



were JP-4 jet fuel (as light nonaqueous-phase liquid), toluene, xylene, PCE,trichloroethylene (TCE), and chlorobenzene (dissolved in the light nonaqueous-phaseliquid). This test was completed in 1996. It is estimated that 99 kg of total hydrocarbon,1.75 kg of total benzene, toluene, ethyl benzene and xylenes (BTEX), 40 g of TCE, lessthan 115 g of PCE, and 40 g of chlorobenzene remained after seven months of bioventing(the co-oxidation study concluded there had been 5.7 percent mass removal). No furtheractive remediation of the JP-4 was undertaken. The placement of the LNAPL within thevadose zone was unlikely to have a negative impact on the DNAPL PCE since JP-4 canserve as an electron donor for biodegradation. The impact of the existing chemicals in theTest Cell was assessed during Phase 1 of the demonstration, and the residual VOCs werenot considered detrimental to the goals of the proposed pilot work.

Preliminary Test Cell Investigation

A soil investigation was completed to assess the distribution and extent of contaminants

The impact of the existingchemicals in the Test Cellwas assessed during Phase1 of the demonstration, andthe residual VOCs were notconsidered detrimental tothe goals of the proposedpilot work.

present within the Test Cell prior to the controlled DNAPL release. Soil samples werecollected from eight boreholes located within the Test Cell in March, April, and May2001 for analysis of priority pollutants and xylenes by gas chromatography. These sampleswere also analyzed for JP-4 using a modified EPA Method 8015B. A total of six VOCswere detected in the soil samples collected from the Test Cell (PCE, TCE, ethyl benzene,toluene, o-xylenes, and m,p-xylenes). At three locations, TCE was present below thewater table at concentrations ranging from 75 to 220 micrograms per kilogram (µg/kg).All other VOCs were only detected in samples collected from the unsaturated zone. JP-4was detected at two locations within the unsaturated zone (9.5 and 11ft bgs). In general,the presence of JP-4 coincided with the detection of VOCs.

PCE DNAPL Release

The Bradford Group from University of Wyoming conducted the PCE DNAPL release inJuly 2001. A total of 100 liters of pure-phase PCE were released into two injection points,one installed in the vadose zone (screened from 4 to 5 feet bgs) and one in the saturatedzone (screened from 12 to 13 feet bgs). The saturated zone injection point is locateddirectly above a coarse-grained/fine-grained sand boundary, and it was expected that itwould form a zone of DNAPL accumulation with a high volumetric saturation above theboundary.

Site Improvements for ESTCP Enhanced Dissolution Experiment

Injection, extraction, and monitoring well installation were completed concurrently withthe soil borehole investigation. Three injection, three extraction, and four fully screenedmonitoring wells were installed between March and May 2001, and a series of soilsamples were collected for laboratory analysis. Thirteen multilevel piezometers (seeExhibit 2 for screen locations) were installed in October 2001. All fully screened wellsand multilevel piezometers were developed in February 2002 following the completion ofthe aboveground recirculation system described below.



Infrastructure and Operation of the Test Cell

The recirculation system consisted of five major elements: flow control, abovegroundtreatment, electron donor addition (as required by phase), groundwater reinjection, and aprogrammable logic controller (PLC) data acquisition and control. Control of theextraction and injection of groundwater within the Test Cell was necessary to simulate anatural aquifer system. Three 0.13-gallon bladder pumps with air pressure controlmanifolds and a 60-gallon air compressor were used to extract and discharge thegroundwater into a 1,000-gallon polyethylene settling tank. The bladder pumps wereexpected to deliver a combined flow of 1 gpm into the settling tank. A Grundfos RediFlow III variable speed transfer pump that allows for remote control of the injection flowrate transferred the groundwater within the settling tank through the abovegroundtreatment system and into the three injection wells. Through the use of the variable speedcontrol, an injection flow rate of approximately 1 gpm was projected.

Aboveground treatment of the extracted groundwater consisted of two granularactivated carbon (GAC) drums in series to prevent the injection of VOC-contaminatedwater into the Test Cell. This was later decreased to one GAC drum. The removal ofVOCs was intended to simulate a natural environment where uncontaminated“upgradient” groundwater would flow through a source area.

The removal of VOCs wasintended to simulate anatural environment whereuncontaminated “upgradi-ent” groundwater wouldflow through a source area.

A multichannel variable flow peristaltic pump with computer input terminal(chemical feed pump) allowed for the automated injection of electron donor to the TestCell during the biostimulation and bioaugmentation phases of the demonstration. Remotecontrol of the extraction, transfer, and chemical feed pumps were accessed through a dataacquisition and control system. The system consisted of an on-site laptop computer withmodem and DSL line, and CITEC software to control all of the inputs and outputs of theequipment. The data acquisition system was programmed to record system data on anhourly basis and saved to a data file at the end of each day. A second program averaged thehourly readings over the entire day and incorporated them in a summarydata file.

The initial testing of the recirculation system required a stepwise testing procedure toensure that all equipment was functioning as intended. The extraction pump air solenoidemergency shutoff, bladder control modules, flow elements, level alarms, and dischargepiping were the first set of units to be tested. Calibration and confirmatory testing of theextraction well flow meters and optimization of the bladder pump extraction rates weretime-consuming. The injection system flow meters were calibrated, and the remotecontrol settings for the biostimulation system were edited as required. For enhancedsafety, high-level alarms were wired to an auto dial-out system in all the abovegroundsecondary containment areas.

Sampling Plan

Exhibit 2 shows the Test Cell site plan with the locations of the multilevel monitoringwells, fully screened monitoring wells, injection wells, and extraction wells. Theevaluation of the effectiveness of biologically enhanced dissolution of the PCE DNAPLwas based on the results of groundwater sampling and analysis. The analytical results fromsamples collected from the extraction wells (EWs) on a weekly basis were used todevelop the schedule for the detailed snap-shot rounds for each phase of the



Exhibit 4. Summary sampling schedule

demonstration. Groundwater samples were collected on multiple occasions following thesystem installation; during the tracer tests; prior to electron donor addition; and before,during, and following bioaugmentation. These samples were analyzed in both the field andin the laboratory depending on the specific parameter being measured. Exhibit 4 lists theanalytical sampling schedule for each sampling location, the analyses performed, and theanalytes reported. Prior to sample collection, the groundwater parameters (pH, dissolvedoxygen, oxidation-reduction potential, and temperature) were measured with aflow-through cell and handheld meters.



RESULTS AND DISCUSSION

No previous remedial activities were completed to treat the PCE source. Water-levelvariations were recorded in the early stages of the study. When the water table fluctuated,there were substantial changes in the observed concentrations of PCE in the uppermultilevel monitoring points. This suggested that there was NAPL-phase PCE suspendedin the unsaturated zone. To remove the mass fluctuations, the water table was maintainedat a constant level through the addition of water to the Test Cell on an as-needed basis.This level was set on the average water table level for DAFB. Thus, the remaining PCE inthe unsaturated zone could still serve as a source to the saturated zone. A soil vaporextraction (SVE) system was operated to extract and calculate vadose zone PCE mass andto refine the potential total mass in the saturated zone. SVE operations removed about 16kg of PCE mass. However, based on PCE extraction, SVE removal was incomplete at theconclusion of the groundwater portion of the study. The following describes the differentgroundwater-based operating stages that were assessed over the operational period.

Phase 1, start-up and shake down, included tracer testing using chloride and bromideto determine flow paths and velocities within the test cell. Phase 2, baseline operation,was operated for 15 months to evaluate the effect of flushing the DNAPL source withgroundwater in the presence of the indigenous microorganisms of the test cell. This phaserequired a substantial amount of time due to the relatively young age of the DNAPLsource and the length of time required to reach a steady-state condition typical ofindustrial source zones. Mass discharge from the extraction wells decreased substantiallyover the months of August to October 2002. During this time, two of the three extractionwells were increasingly impacted by silt buildup within the bladder of the pump.Therefore, the groundwater samples collected over this time period represented thecontribution of only one of the extraction wells. With the pumps repaired in November2002 and groundwater recirculation continued, the mass discharge increased topre-August 2002 levels, and then decreased again to lower levels in February 2003.

The high mass discharge observed early in Phase 2 up to the post-extraction wellrepair was likely due to the high surface area of the mobile PCE stringers present withinthe test cell. The treatment rate established in the last two months of Phase 2 is likelyrepresentative of a more stable DNAPL mass. It is noteworthy to mention that regardlessof the operational status of the extraction wells, the ratio of each chlorinated ethene to thetotal ethenes in the groundwater remained constant, with PCE representing 99.8 percentof the total ethenes present (Exhibit 5). The very low concentrations of other chlorinated

The high mass dischargeobserved early in Phase 2up to the post-extractionwell repair was likely dueto the high surface area ofthe mobile PCE stringerspresent within the test cell.

ethenes detected in samples from the extraction wells and multilevel piezometerscollected during Phase 2 suggest that in the absence of a suitable electron donor, theindigenous microbial community was not capable of dechlorinating the PCE DNAPL. Thiswas corroborated by the results of the stable carbon isotopic analysis of samples collectedover this time period where PCE 13C/12C ratios from dissolved-phase PCE wereunchanged over Phase 2 (data not provided but to be published by others). This suggeststhat in the absence of a suitable electron donor, the indigenous microbial community wasnot capable of measurable PCE dechlorination.

In Phase 3, biostimulation, with the addition of a pair of electron donors (sodiumlactate and ethanol), was operated for a period of five months. On March 5, 2003, thetreated groundwater was amended once daily with a combination of ethanol and sodium



Exhibit 5. Proportion of ethenes in extracted groundwater

lactate. Nominally the time weighted average electron donor addition for ethanol was 63milligrams per liter (mg/L) for the biostimulation phase and 20 mg/L for thebioaugmentation phase, and for lactate 22 mg/L and 14 mg/L for both the biostimulationand bioaugmentation phases. The purpose of adding electron donor to the injection waterwas to increase the activity of the indigenous microorganisms and attempt to stimulatecomplete dechlorination of the PCE. The relatively short duration of this operationalphase was based on the comparison of analytical results reported in previous studies of theDover Aquifer and the results of the laboratory experiments completed at the Universityof Toronto (Sleep et al., 2006), which showed there was very little dechlorinating activityexhibited by the indigenous microorganisms. The mass discharge from the extractionwells remained relatively stable over the electron donor addition phase, confirming theresults of the laboratory tests. The dominant chlorinated ethene within the extractedgroundwater continued to be PCE (99 percent of total ethenes), with low estimatedconcentrations of TCE and cis-1,2-dichloroethylene (Exhibit 5).

On July 18, 2003, 60 liters of KB-1TM (SiREM Labs, Guelph, Ontario) were injectedinto five locations within the Test Cell (Exhibit 2). This was the only KB-1TM addition tothe Test Cell during the demonstration. Phase 4, bioaugmentation with KB-1TM andcontinued electron donor addition, was operated for a period of 20 months. As expected,the mass discharge of VOCs from the DNAPL increased with time and averaged a rate ofapproximately 100 mmol/day (Exhibit 5). The calculated mass discharge from theextraction wells decreased during August 2003 to December 2003, while the dominantchlorinated ethene detected in groundwater samples changed from PCE (86 percent inAugust 2003) to cis-DCE (55.8 percent in December 2003). Over the bioaugmentationphase, biofouling was observed and the extraction wells needed to be rehabilitatedfrequently.



Phase 5 (post-bioaugmentation) began in late February 2005 (electron donor additionwas terminated, but groundwater recirculation continued). During this phase, theproduction of ethene within the groundwater increased significantly and the percent ofcis-DCE decreased to 16 percent in May 2005. By May 2005, ethene represented 70percent of the total ethenes in the groundwater in the test cell. The lower-than-expectedmass discharge from the extraction wells might be a function of preferential partitioningof the dechlorination products back into the DNAPL source. The system was shut down(i.e., recirculation stopped) on May 23, 2005.

Given the longevity of the experiment and the observations in the Test Cell, a secondtracer test was completed to corroborate field evidence of biomass fouling in the TestCell. The results showed significant differences in flow velocities between the two tracertests and that much of the groundwater flow reaching the extraction wells was from a fewkey flow paths. Given the reductions in flow (biomass occlusion is suspected) during theelectron donor stages, additional data evaluation will be performed to determine if massflux estimates have been underestimated or overestimated. After this work is completed,additional results (mass flux over time and during each phase and snap-shot samplinground) will be generated and will be available for inclusion in this review.

SUMMARY AND CONCLUSIONS

The field component of the project was completed in May 2005. The overall goals of theproject demonstration were met. The estimated total mass removed was 77 kg of PCE. Itwas estimated at the completion of the test that about 47 percent of the PCE massremained in the Test Cell. Important achievements include demonstrating the ability todegrade a PCE DNAPL source to ethene and obtaining significant information on theimpacts to the microbial populations and corresponding isotope enrichments duringbiodegradation of a source area.

REFERENCES

Johnston, R. H. (1973). Hydrology of the Columbia (Pleistocene) Deposits of Delaware—An appraisal of a

regional water-table aquifer. Bulletin No. 14. Newark, DE: Delaware Geological Survey.

Payne, F. C., Suthersan, S. S., Nelson, D. K., Suarez, G., Tasker, I. R., & Akladiss, N. (2006). Enhanced

reductive dechlorination of PCE in unconsolidated soils. Remediation, 17(1), 5–21.

Sleep, B. E., Seepersad, D. J., Mo, K., Heidorn, C. M., Hrapovic, L., Morrill, P. L., et al. (2006) Biological

enhancement of tetrachloroethene dissolution and associated microbial community changes.

Environmental Science & Technology, 40, 3623–3633.

Wymore, R. A., Macbeth, T. W., Rothermel, J. S., Peterson, L. N., Nelson, L. O., Sorenson, K. S., et al. (2006).

Enhanced anaerobic bioremediation in a DNAPL residual source zone: Test Area North case study.

Remediation, 16(4), 5–22.

Carmen A. Lebron is a senior environmental engineer with the Naval Facilities Engineering Service Center.

Ms. Lebron’s expertise is in managing projects related to biodegradation of DNAPLs, remediation of DNAPL

source zone areas, and application of molecular biological tools.







Timothy McHale is the program manager for the Dover National Test Site in Dover, Delaware. His expertise

is in hydrology, contaminant migration, regulatory permitting, and implementation of innovative approaches to

site restoration.

Robroy Young is an environmental scientist at the Dover National Test Site in Dover, Delaware. Mr. Young’s

expertise is in field investigations and implementation of innovative remediation technologies.

Dale Williams is an analytical chemist at the Dover National Test Site in Dover, Delaware. Mr. Williams’s

expertise is in multifluid gas chromatograph analyses in support of innovative environmental remediation

technologies.

Matthew G. Bogaart is a practicing hydrogeologist at Geosyntec Consultants, Inc. Mr. Bogaart’s expertise

is in the development and application of in situ remediation technologies for recalcitrant organic compounds.

David W. Major is a managing principal of Geosyntec Consultants, Inc, an adjunct professor at the University

of Toronto, and associate editor of Ground Water Monitoring and Remediation. Dr. Major’s expertise is in the

development and application of in situ remediation technologies, particularly bioremediation of recalcitrant

organic compounds.

Michaye L. McMaster is a senior remediation scientist at Geosyntec Consultants, Inc. Mr. Caster obtained a

B.Sc. in biology and an M.Sc. in earth sciences from the University of Waterloo. His expertise is in the application

of in situ remedial technologies for treatment of chlorinated solvents and other compounds.

Ian Tasker, PhD, is chief scientist at EnDyna, where he provides management and technical expertise in

environmental technologies and nuclear waste, and serves as program advisor to the ITRC’s Bioremediation of

Dense Nonaqueous-Phase Liquids Team. He has 30 years of experience in the environmental field as a laboratory

scientist, program manager, and consultant.

Naji Akladiss , P.E., is a project manager with the Main Department of Environmental Protection, Bureau

of Remediation, and leader of the ITRC’s Bioremediation of Dense Nonaqueous-Phase Liquids Team. He is an

environmental engineer with 18 years’ experience in environmental technologies and Superfund remediation.


Documents

Pilot-scale evaluation using bioaugmentation to enhance PCE dissolution at dover AFB national test site