Novel Subsurface Biobarriers to Contain and Remediate Contaminated Ground Water
Robert Sharp, Manhattan College, Bronx, NY
Al Cunningham, Montana State University, Bozeman, MT
John Komlos, Jr., Princeton University, Princeton, NJ

Degradation of Carbon Tetrachloride in a Reducing Groundwater Environment: Implications for Natural Attenuation
Andy Davis, Geomega, Boulder, CO
C. Peck, Chevron Environmental Management Co., San Ramon

Treatment of Contaminated Groundwater Using NanoFe^TM Technology
Harch Gill, PARS Environmental, Inc., Robbinsville, NJ
Kaiti Liao, PARS Environmental, Inc., Robbinsville, NJ

Optimization of an Extraction Well Using Three-Dimensional Capture Zones 
Mary O’Reilly, CH2M HILL, Otis ANG Base, MA
John Glass, CH2M HILL, Herndon, VA
Scott DeHainaut, CH2M HILL, Otis ANG Base, MA 
Rose Forbes, Air Force Center for Environmental Excellence, Otis ANG Base, MA

Remediation of Petroleum-Containing Soil and Groundwater at a Former Rail Yard Locomotive Fueling Area
Scott R. Compston, Malcolm Pirnie, Inc., Latham, NY
Bruce R. Nelson, Malcolm Pirnie, Inc., Latham, NY
Scott A. Underhill, Malcolm Pirnie, Inc., Latham, NY
LeeAnn Thomas, Canadian Pacific Railway, Minneapolis, MN

MRC™ Treatment of a VOC and Metals Impacted Unconsolidated Aquifer
Jonathan K. Child, Fuss & O’Neill, Inc., West Springfield, MA
Timothy J. St. Germain, Fuss & O’Neill, Inc., West Springfield, MA   

Remediation Optimization Achieved by Bundling Complementary Treatment Technologies

Richard T. Cartwright, P.E., CHMM, Vice President, MEC^X, LLC, 8096 Clarherst Drive, East Amherst, NY 14051, Tel: 713-412-9697, Fax: 713-585-7049, Email: richard.cartwright@mecx.net
R. Thomas Numbers, P.E., Vice President, MEC^X, LLC, 3005 Margaret Jones Lane, Williamsburg, VA 23185, Tel: 757-220-6666, Fax: 757-220-3396, Email: thomas.numbers@mecx.net

An innovative sequence of four bundled complementary in-situ soil and groundwater treatment technologies has been developed to reduce total contaminant mass encountered at difficult to treat remediation sites. The first step is to pre-condition low permeability soils using either chemical and/or mechanical means.

The second step is to apply an optimized enhancement of the Traditional Fenton’s Reagent chemical oxidation process. Unlike previous applications of Traditional Fenton’s Reagent, the new emphasis is on optimization of the “Total Contaminant Mass Desorption Process”.

High temperature (greater than 180^oF) applications in the saturated zone have resulted in runaway reactions when the lower explosion limits (LEL) were exceeded. Low temperature (less than 100^oF) applications have resulted in problems with dissolved phase contaminant concentration rebound. The new optimized approach, whereby the saturated zone temperature is maintained consistently between 140^oF and 170^oF, effectively desorbs both adsorbed and absorbed contaminants from the soil matrix.   

The desorption extraction step facilitates the third and fourth steps, which are biotreatment polishing steps used to reduce total contaminant mass transferred from the soil matrix into the dissolved phase in the saturated zone. The third step is an aerobic treatment process, which optimally produces stable concentrations of dissolved oxygen to biodegrade hydrocarbons in the contaminated groundwater. A patented process of water electrolysis used with a submersible pump and packer system recirculates oxygen enriched groundwater into the aquifer. It moves water only in recirculation. No water is withdrawn from the aquifer and no handling of water or permitting is required.

If chlorinated contaminants are also present, a fourth anaerobic treatment process is employed. Emulsified food-grade soybean oil is then injected into the aquifer, which slowly dissolves over several years providing a carbon and energy source to accelerate biodegradation. This innovative sequence of four complementary treatment technologies optimizes the reduction of total contaminant mass.

Novel Subsurface Biobarriers to Contain and Remediate Contaminated Ground Water

Robert Sharp, Manhattan College Dept. of Environmental Engineering, 3825 Corlear Avenue, Rm 314, Bronx, NY 10463, Tel: 718-862-7169, Fax: 718-862-8018, Email: Robert.sharp@manhattan.edu
Al Cunningham, Montana State University, Center for Biofilm Engineering, 312 EPS Building, Bozeman, MT, Tel: 406-994-6109, Email: Al_C@erc.montana.edu
John Komlos, Jr., Department of Civil and Environmental Engineering, Princeton University, E-125 Engineering Quad, Princeton, NJ 08544, Tel: 609-258-5805, Email:  jkomlos@princeton.edu

This paper describes over a decade of work including laboratory studies, pilot studies and a field demonstrations to develop effective multi-purpose subsurface biobarriers that can be used to significantly decrease the hydraulic conductivity of an aquifer, while simultaneously mineralizing toxic groundwater contaminants.  These novel biobarriers rely on starved cell technology to properly place and construct subsurface barriers using environmental isolates obtained at the contaminated sites.

The types of starved cell biobarriers that have been developed include single specie static biobarriers for plume containment and saltwater intrusion abatement, reactive biobarriers for containment and degradation of BTEX and nitrate, and dual-species reactive biobarriers for containment and degradation of chlorinated compounds.  One example includes a field demonstration of a reactive subsurface biological barrier that has been in operation for 4 years.  Results indicate that the biobarrier can reduce permeability by more than three orders of magnitude over an extended period of time without significant maintenance.  Simultaneously, this biobarrier can degrade high concentrations of nitrate (> 100 mg/l) to meet drinking water standards (< 10 mg/l).  Other single specie reactive barriers that have been developed include one capable of degrading BTEX and TCE.   Bench-scale studies were used to develop a dual-species reactive biobarrier aimed at mineralizing TCE.  This reactive biobarrier combines a well characterized TCE degrading environmental isolate with the facultative biofilm producer used in the field study to produce a dual species biofilm capable of partially plugging porous media (90% reduction in K) while completely mineralizing TCE.  In addition, the results demonstrate that varying nutrient feed can be used to control both TCE degradation rates and hydraulic conductivity reduction.  Additional field installations of this novel technology are planned, including barriers to remediate TCE, gasoline and MTBE plumes.  Currently, work is being carried out to develop starved-cell biobarriers that can remediate heavy metals and radionuclides.

Degradation of Carbon Tetrachloride in a Reducing Groundwater Environment: Implications for Natural Attenuation

Andy Davis, Geomega, 2995 Baseline Road, Suite 202, Boulder, CO 80303, Tel: 303-938-8115, Email: andy@geomega.com
C. Peck, Chevron Environmental Management Co., 6001 Bollinger Canyon Road, San Ramon 94583

Several laboratory experiments have demonstrated degradation of carbon tetrachloride (CT) in groundwater, but there appear to have been no corroborating long-term field studies. Investigations conducted in 1989 and 1999 at an industrial site constructed on an infilled estuarine environment in France provide data over a decade for which CT degradation could be evaluated. A Dense Non-Aqueous Phase Liquid (DNAPL) containing oil and >90% CT that was present in 1989 was absent in the extremely reducing site groundwater in both 1999 and 2000 (average Eh = -170 mV at pH 7, sulfide up to 21 mg L^-1, and Fe⁺² up to 3.2 mg L^-1). These conditions facilitated dechlorination of CT to chloroform (CF) present at up to 46 mg L^-1, and methylene chloride (up to 75 mg L^-1). Carbon disulfide (CS₂), a terminal degradation product in reducing environments in laboratory experiments, was present at a mass ratio averaging 2.4:1 CF:CS₂, indicative of abiotic degradation. The lack of detection of the separate phase CT, the ratio of CF:CS₂, the presence of low molecular weight organic acids (i.e., acetate ~900 mg L^-1; citrate 360 mg L^-1; and propionate, up to 111 mg L^-1) and pyrite in conjunction with excess inorganic Cl in groundwater are all indicators of ongoing degradation of the chlorinated compounds. However, while natural attenuation of chloromethanes may be a viable adjunct to strategies designed to remediate CT in reducing groundwater, its efficacy is hard to quantify in complex field environments where upgradient sources are still present.

Treatment of Contaminated Groundwater Using NanoFe^TM Technology

Harch Gill, Ph. D., PARS Environmental, Inc., 6A South Gold Drive, Robbinsville, NJ 08691, Tel: 609-890-7277, Fax: 609-890-9116, Email: hgill@parsenviro.com
Kaiti Liao, PARS Environmental, Inc., 6A South Gold Drive, Robbinsville, NJ 08691, Tel: 609-890-7277, Fax: 609-890-9116, Email: kliao@parsenviro.com

NanoFe^TM Technology is an innovative remediation technology for treating a wide range of recalcitrant contaminants.  NanoFe consists of supported submicron (<10^-6 meter), bacteria-sized particles of zero valent iron (Fe⁰) and trace amounts of a noble metal catalyst.  NanoFe is an extremely versatile remediation tool given its high reactivity and extremely small particle size (typical particle sizes are on the order of 10-100 nanometers).  NanoFe can effect the rapid destruction of a wide range of recalcitrant contaminants on either an in-situ or ex-situ basis.  In the in-situ application, a slurry mixture of NanoFe and water is injected under pressure or by gravity into the contaminant plume.  These particles have good flow characteristics and remain in suspension over extended periods of time to flow with the groundwater, while offering high reactivity that can dechlorinate chlorinated hydrocarbon contaminants. 

NanoFe^TM Technology has been applied at several sites to treat groundwater contaminated with a variety of chlorinated hydrocarbons.  The injected NanoFe significantly reduces the concentrations of chlorinated contaminants within approximately three days.  Additionally, the injected NanoFe produced reducing conditions that fostered continuing natural attenuation of contaminants.  This paper presents the results from several field applications and evaluates the distribution and effectiveness of the NanoFe. 

Optimization of an Extraction Well Using Three-Dimensional Capture Zones 

Mary O’Reilly, CH2M HILL, 318 East Inner Road, Otis ANG Base, MA 02542, Tel: 508-968-4670 ext 5629, Fax: 508-968-4490, Email: moreilly@ch2m.com
John Glass, CH2M HILL, 13921 Park Center Road, Suite 600, Herndon, VA 20171-5416, Tel: 703-471-1441 ext 4341, Fax: 703-471-1508, Email: jglass@ch2m.com
Scott DeHainaut, CH2M HILL, 318 East Inner Road, Otis ANG Base, MA 02542, Tel: 508-968-4670 ext 5629, Fax: 508-968-4490, Email: sdehaina@ch2m.com
Rose Forbes, Air Force Center for Environmental Excellence, 318 East Inner Road, Otis ANG Base, MA 02542, Tel: 508-968-4670 ext 5613, Fax: 508-968-4490, Email: rose.forbes@brooks.af.mil

Aquifer remediation at several groundwater contamination sites on the Massachusetts Military Reservation (MMR) is being expedited by periodic optimization of the extraction, treatment, and reinjection systems.  Optimization activities may involve adjustment of pumping and reinjection rates, addition or removal of wells, or packing off sections of well screens to focus remediation efforts on the most critical depth intervals.  Because groundwater flow is fully three-dimensional, system modifications are guided by a combination of groundwater monitoring and three-dimensional modeling.  An example is a single-well hydraulic containment system that was installed to intercept a long, narrow trichloroethene (TCE) plume that passes beneath a 1000 foot land mass between two ponds before the plume discharges into the downgradient pond.  Based on monitoring results from 1999, the TCE plume was delineated with a width of 50 to 75 feet, a thickness of less than 50 feet, and concentrations ranging up to 2200 micrograms per liter (µg/L).  Since startup of the extraction well in January 2000, the plume trajectory has shifted, and TCE has not been detected at concentrations exceeding the maximum contaminant level of 5 µg/L in the upgradient monitoring network.  However, influent concentrations at the extraction well remain consistent with the original plume delineation, with concentrations ranging up to 90 µg/L at a pumping rate of 150 gallons per minute (gpm).  To optimize the performance of the well and locate the shifted plume, a field investigation program was designed, based on the results of three-dimensional hydraulic capture-zone delineation using the groundwater flow model.  Investigation results and additional modeling of optimization scenarios were used to focus the extraction stress on the most contaminated portion of the aquifer while maintaining hydraulic containment of the plume.

Remediation of Petroleum-Containing Soil and Groundwater at a Former Rail Yard Locomotive Fueling Area

Scott R. Compston, Malcolm Pirnie, Inc., 15 Cornell Road, Latham, NY 12110, Tel: 518-786-7349, Fax: 518-786-8645, Email: scompston@pirnie.com
Bruce R. Nelson, Malcolm Pirnie, Inc., 15 Cornell Road, Latham, NY 12110, Tel: 518-786-7349, Fax: 518-786-8645m Email: bnelson@pirnie.com
Scott A. Underhill, Malcolm Pirnie, Inc., 15 Cornell Road, Latham, NY 12110, Tel: 518-786-7349, Fax: 518-786-8645, Email: sunderhill@pirnie.com
LeeAnn Thomas, Canadian Pacific Railway, 501 Marquette Avenue, Suite 804, Minneapolis, MN 55402, Tel: 612-904-6130, Fax: 612-904-6147, Email: leeann_thomas@cpr.ca

Malcolm Pirnie, Inc. implemented a multi-faceted remedial program at a former locomotive fueling area (FLFA) at a rail yard in upstate New York to address diesel-affected soil and groundwater.  Mainline tracks running through the FLFA prohibited removal of affected soil and, consequently, an in-situ remedy was developed.  The remedy combines air sparging to provide oxygen to intrinsic diesel-degrading microorganisms and to volatilize petroleum compounds, and soil vapor extraction to actively remove volatilized diesel compounds from the subsurface.  System components include vapor extraction and air sparging wells within the FLFA and low flow biosparging wells between the FLFA and down gradient properties.  The biosparging wells create an oxygen barrier to migrating diesel compounds.  Based on vapor extraction flow rates and the concentration of volatile organic compounds (VOCs) in extracted air, an estimated 1,000 pounds of petroleum mass have been removed by the vapor extraction system to date.  Mass removal and biological activity is strongly correlated with seasonal fluctuations in subsurface temperature, which varies by more than eight degrees Celsius in the treatment zone over the course of a year.  Analyses of microbial biomass in the treatment area indicate that diesel-degrading organisms increased by four orders of magnitude in unsaturated soil and by three orders of magnitude in saturated soil within five months of system start up.  Regulated VOC concentrations in soil have decreased between 83 and 98 percent, while regulated semi-volatile organic compound (SVOC) concentrations in soil have decreased by as much as 90 percent in the treatment area in approximately 18 months.  Concentrations of petroleum compounds in groundwater have been reduced to less than standards over the majority of the site.  This integrated in-situ approach to the treatment of diesel-impacted soil and groundwater has greatly reduced cleanup costs and cleanup time for the site.

MRC™ Treatment of a VOC and Metals Impacted Unconsolidated Aquifer

Jonathan K. Child, Fuss & O’Neill, Inc., 78 Interstate Drive, West Springfield, MA  01089, Tel: 413-452-0445 x4414, Email:  jchild@fando.com
Timothy J. St. Germain, Fuss & O’Neill, Inc., 78 Interstate Drive, West Springfield, MA  01089, Tel: 413-452-0445 x4412, Email: tgermain@fando.com

In-situ metals and chlorinated solvents remediation with Metals Remediation Compound (MRC™) is being evaluated as a method for remediating a mixed chlorinated volatile organic compound (VOC) and dissolved metals plume at a former plating facility in Massachusetts.  MRC™ is a new, injectable remedial additive developed by Regenesis, San Clemente, CA for the in-situ treatment of co-mingled metal and solvent plumes.  The MRC™ product is designed to release a polylactate polymer and a benign organosulfur compound to groundwater and facilitate enhanced reductive dechlorination of chlorinated VOCs and the formation of insoluble metal-sulfide solids to immobilize dissolved metals.

The primary constituents of concern at the site are chlorintated VOCs (primarily 1,1,1-trichlorethane and tetrachloroethene) and dissolved nickel.  The source of the release is a former plating facility and associated drywell.  Removal of the drywell and approximately 320 tons of soil was conducted in July 2000.  Post-excavation assessment and monitoring activities indicate that residual impacts remain in the vicinity of the former drywell source area.  Additional remedial measures are required to achieve further source reduction and prevent off-site contaminant migration.  

The MRC™ Pilot Test was initiated in December 2003 with the injection of 540 pounds of MRC™ by GeoprobeÒ within an approximate 250 square foot area.  MRC™ was injected over an approximate 15-foot vertical interval between a depth of approximately 5 and 20 feet at nine locations.  A baseline groundwater monitoring event was conducted one day prior to MRC™ injections.  Geochemical effects of the MRC™ injection are being monitored through three post-injection groundwater monitoring events conducted over a six month period.  Each monitoring event includes the measurement of field parameters and a comprehensive suite of laboratory analyses including contaminants of concern, dissolved gases, metabolic acids, and a variety of inorganic parameters.

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