Stimulating Polychlorinated Biphenyl (PCB) Dechlorination by Controlling the Availability of Electron Donor
Tao Yan, University of Minnesota, Minneapolis, MN 
Paige J. Novak, PhD, University of Minnesota, Minneapolis, MN

Bioremediation of Bedrock Groundwater contaminated with Tetrachloroethene, Trichloroethene, Trichloroethane, Toluene and Hexane
Jonathan Aisner, LSP
William E. Baird, Web Engineering Associates, Inc.

Substrate Release Composition (SRC): An Innovative Tool for the Anaerobic  Bioremediation of Chlorinated Organics
Eric C. Hince, Geovation Technologies, Inc.

In-situ Bioremediation of a Chlorinated Solvent Residual Source in Unconsolidated Sediments and Bedrock Using Bioaugmentation
Stephen Finn and Allen Kane, Golder Associates
John Vidumsky, E.I. DuPont de Nemours and Company
David W. Major, GeoSyntec Consultants
Nicholas Bauer, Saltire Industrial, Inc.  

Mulch Biowall for Enhanced Bioremediation of Chlorinated Solvents
Allison Love, Parsons,  Inc.
Bruce M. Henry, Parsons,  Inc.
Ted Hartfelder, Parsons, Inc.
James R. Gonzales, Air Force Center for Environmental Excellence 
Patrick E. Haas, Mitretek Systems

Ex Situ Bioremediation of Low Concentrations of Perchlorate and Explosives in Groundwater
Katherine R. Weeks, AMEC Earth & Environmental, Inc.
David L. Hill, National Guard Bureau
Scott C. Veenstra, AMEC Earth & Environmental, Inc.

Bioremediation of a Railroad Diesel Fuel Spill in Palmer, Massachusetts
Todd D. Kirton and Paul G. Beaulieu, Tighe & Bond 

Stimulating Polychlorinated Biphenyl (PCB) Dechlorination by Controlling the Availability of Electron Donor

Tao Yan, PhD candidate, Department of Civil Engineering, University of Minnesota, 122 Civil Engineering Building, 500 Pillsbury Drive, Minneapolis, MN 55455, Tel: 612-626-9536
Paige J. Novak, PhD, Department of Civil Engineering, University of Minnesota, 122 Civil Engineering Building, 500 Pillsbury Drive, Minneapolis MN 55455, Tel: 612-626-9846

Anaerobic dechlorination of PCBs removes chlorines from highly chlorinated congeners, and thus reduces their toxicity and increases their aerobic biodegradability. Most of the dechlorination observed in the environment and laboratory occurs under methanogenic conditions, where other microorganisms, including methanogens, may compete with the PCB dechlorinators in a sediment community.  For microorganisms catalyzing redox processes, the availability of electron acceptors, electron donors, and carbon sources will determine the energy available for microorganism growth. Work in our laboratory has shown that some PCB dechlorinators and methanogens share the same electron donor, hydrogen.  It is hypothesized that PCB dechlorinators and methanogens will have different hydrogen affinities and thresholds and will respond differently to environmental stimuli.  Therefore, by controlling and limiting the availability of hydrogen the growth of PCB dechlorinators will be favored against methanogens. Research in our laboratory has found that the acclimation phase of PCB dechlorination was shortened by two months in reactors amended with 0.1% H₂ (equivalent to 780 nM), compared to unamended reactors or reactors amended with 1% hydrogen. It is our hypothesis that the PCB dechlorinators in sediment of other source will behave similarly, and there is an optimal (and low) hydrogen concentration that enhances PCB dechlorination in general while restricting the growth of methanogens.  Experiments are currently in progress to verify this hypothesis and determine the hydrogen affinity of PCB dechlorinators and the population dynamics of sediment cultures in the presence of varying electron donors.

Bioremediation of Bedrock Groundwater contaminated with Tetrachloroethene, Trichloroethene, Trichloroethane, Toluene and Hexane

Jonathan Aisner, LSP, and William E. Baird, PE, LSP, Web Engineering Associates, Inc., 106 Longwater Dr., Norwell, MA 02061, Tel. 781-878-7766

Located in Eastern Massachusetts, the geology of the site is approximately 10 feet of glacial till over granite.  The bedrock is competent at ± 40 feet.  The groundwater elevation is 8 to 10 feet below grade surface.  The aerial extent of the site is approximately 1 acre.  Numerous releases occurred at the site from leaking underground piping, tank overfills and leaking drums.  The highest concentrations of contaminants detected at the site are as follows: Trichloroethane-940ppm, Trichloroethene-67ppm, Tetrachloroethene-17ppm, Toluene-14ppm, Hexane-LNAPL.  The groundwater has a high concentration of iron. 

In June 2001, a pump and treat bioreactor system was installed.  The system consists of pumping from two perimeter down-gradient recovery wells into a 500 gallon plastic tank aerated by a small compressor followed by another 500 gallon plastic settling tank, two parallel bag filters and a 1,000 lb. carbon canister.  The effluent flows by gravity into an up-gradient leaching field.

The average daily flow rate treated is 5,700 gallons.  Since startup, 4.85 million gallons of groundwater have been treated.  The capacity of the leaching field limits the systems flow rate.  In the summer, with water temperatures approaching 68^oF, the bioreactor system removed more than 95% of the contaminants.  In the winter, with water temperatures at 43^oF, the system efficiency declined to ±50%.  The average daily influent of contaminants is 559mg.  The average daily effluent is 118mg.  The average daily influent of chlorine is 353mg.  The average daily effluent of chlorine is 76mg. 

The system did not work until microbes and nutrients were added to the first bioreactor.    The microbes added to the first bioreactor are a consortium of aerobic hydrocarbon degraders and aerobic chlorinated compound degraders. 

The capital cost of the system is less than $5,000.00.  Utility costs are approximately 160 kw/month.  The monthly cost of microbes is $1,300.00.

Substrate Release Composition (SRC): An Innovative Tool for the Anaerobic  Bioremediation of Chlorinated Organics

Eric C. Hince, P.G., Geovation Technologies, Inc., 468 Route 17A, Florida, NY, 10921, Tel: 845-651-4141, Fax: 845-651-0040, Email: echince@geovation.com

SRC is a new anaerobic bioremediation product that consists of a complex blend of substrates in granular form.  SRC has been demonstrated to promote the anaerobic catabolism of chloro-organic contaminants ranging from toxaphene to TCA, PCE, TCE, cDCE and mixtures thereof in several different hydrogeologic settings. Applications have included targeted treatment of NAPLs and source-area aquifer media.  As opposed to other substrates that require significant preparation, pumping and injection, SRC has been applied by the comparatively simple method of pouring the SRC granules or briquettes directly into conventional PVC wells by gravity.  Treatment methods have generally consisted of the direct application of SRC into 2-in. and 4-in. diameter PVC wells located and screened so as to be within or immediately upgradient of source areas and suspected NAPL zones.  Subsequent operation and maintenance of the treatment wells has been minimal.  Post-treatment ground-water data from several ongoing pilot studies has consistently shown demonstrable reductions in the concentrations of parent chloro-organic compounds in ground-water including toxaphene, TCA and PCE.  Interesting observations have included that whereas the relative proportions of cDCE to parent compounds have increased in response to SRC treatment, cDCE does not appear to be accumulating and no increases in vinyl chloride have been observed.  Microscopy analyses and DNA assays have demonstrated that SRC promotes a robust and diverse anaerobic consortia of bacteria, archea and fungi.  A composite interpretation of chloro-organic, biogeochemical, trace gas and microbial ecology data from several sites suggests that SRC has stimulated the anaerobic mineralization of chloro-organics in a manner not explained by simple reductive dechlorination alone.  Candidate processes being investigated by the author include a novel chloro-organic catabolic process linked to anaerobic methane oxidation in conjunction with reductive dechlorination.  Data on site conditions, SRC treatment methods and monitoring results from several ongoing pilot programs will be presented.

In-situ Bioremediation of a Chlorinated Solvent Residual Source in Unconsolidated Sediments and Bedrock Using Bioaugmentation

Stephen Finn and Allen Kane, Golder Associates, 1951 Old Cuthbert Rd, Ste 301, Cherry Hill, NJ 08034, Tel: 856-616-8166, Fax: 856-616-1874, Email: akane@golder.com
John Vidumsky, E.I. DuPont de Nemours and Company, Barley Mill Plaza 27/2267, P.O.Box 80027, Wilmington, DE, USA  19880-0027, Tel: 302-892-1378, Fax: 302-892-7641 , Email:  john.e.vidumsky@usa.dupont.com
David W. Major, GeoSyntec Consultants, 160 Research Lane, Suite 206, Guelph, Ontario, Canada N1G 5B2, Tel: 519-822-2230, Email: dmajor@geosyntec.com
Nicholas Bauer, Saltire Industrial, Inc., 12030 Sunrise Valley Drive, Suite 300, Reston, VA 20190, Tel: 703-391-7702, Fax: 703-391-7703, Email: nbauer@erols.com

The Caldwell Trucking Superfund Site is located in Essex County, NJ, and covers approximately 15 acres.  Groundwater occurs in both the glacial deposits and the fractured bedrock, which are hydraulically connected.  Contamination consists of chlorinated ethenes and ethanes, principally trichloroethene (TCE), extending approximately 4,000 ft downgradient of the site.  TCE concentrations in the source area were as high as 700,000 mg/L (about 60% of TCE solubility).  Natural biodegradation is present over much of the site; however some areas, particularly in the source area, appeared to be substrate limited.  Therefore, the Potentially Responsible Parties proposed and implemented a comprehensive groundwater remedy that included bioremediation of the source area. Microcosm studies demonstrated that complete degradation of the contaminants could be achieved.  A field pilot test of in-situ enhanced bioremediation in the source area was initiated in 2001.  The layout included six nutrient injection wells and seven downgradient monitoring wells (wells screened in glacial deposits and fractured bedrock).  Injection wells were bioaugmented with a culture of naturally occurring microorganisms (KB-1 Culture of dehalococcoides ethenogenes) in March 2001. In over sixteen months of operation, the system was optimized by adjustment of the amendment composition and the injection frequency.  The initial equimolar mixture of methanol, acetate, and lactate was modified in February 2002 to eliminate acetate and increase the lactate concentration.  The injection frequency was also increased from monthly to weekly to daily in order to achieve more consistent biodegradation activity throughout the treatment zone.  Gene probe techniques were used to verify initial and continued survival and propagation of the KB-1 Culture organisms.  The pilot test demonstrated the complete degradation of TCE to ethene and 1,1,1-trichloroethane to ethane in areas that had previously shown little if any natural biodegradation.  Approximately 50% reduction of 1,1,1-TCA and 70% - 100% reduction of TCE was achieved.

Mulch Biowall for Enhanced Bioremediation of Chlorinated Solvents

Allison Love, Parsons,  Inc., 1700 Broadway Blvd., Suite 900, Denver, CO 80290, Tel: 303-764-8824 Fax: 303-831-8208, Email: allison.love@parsons.com
Bruce M. Henry, Parsons,  Inc., 1700 Broadway Blvd., Suite 900, Denver, CO 80290 , Tel: 303-764-1986, Fax: 303-831-8208, Email: bruce.henry@parsons.com
Ted Hartfelder, Parsons, Inc., 1700 Broadway Blvd., Suite 900, Denver, CO 80290, Tel: 303-764-1918 Fax: 303-831-8208, Email: ted.hartfelder@parsons.com
James R. Gonzales, Air Force Center for Environmental Excellence, Technology Transfer Division, 3207 Sidney Brooks Road, San Antonio, TX  78235, Tel: 210-536-4324, Fax: 210-536-4330, Email: james.gonzales@hqafcee.brooks.af.mil
Patrick E. Haas, Mitretek Systems, 13526 George Road, Suite 200, San Antonio, TX  78230, Tel: 210-479-0481, Fax: 210-479-0482, Email: patrick.haas@mitretek.org

A permeable mulch biowall was installed at Altus Air Force Base (AFB), Oklahoma in June 2002 to stimulate reductive dechlorination of chlorinated solvents in groundwater at Landfill 3.  The remedial objective of the biowall is to attenuate and contain a shallow groundwater plume contaminated with trichloroethene (TCE) and cis-1,2-dichloroethene (cDCE).  Mulch and compost are byproducts of the landscaping and agricultural industries, and can often be obtained for the cost of handling alone.  These substrates are intended to be used as solid-phase, long-term carbon sources to stimulate reductive dechlorination of chlorinated compounds over periods several years.

The biowall was installed in 4 days using a continuous trencher, measuring 455 feet long by 24 feet deep by 1.5 feet wide.  The biowall is composed of approximately 300 cubic yards of bark mulch, 60 cubic yards of cotton gin compost, and 265 cubic yards of sand (to maintain permeability).  Depth to water varies from 6 to 8 feet, and the trench is intended to intercept over 80 percent of the groundwater plume contaminant flux.  Performance monitoring was conducted in July and September 2002.

Preliminary data indicate that organic carbon within the biowall has been sufficient to induce sulfate reduction and methanogenesis, oxidation-reduction conditions that are conducive to reductive dechlorination.  Elevated levels of metabolic acids (primarily propionic and butyric acids) indicate a high level of biological activity.  Fermentation of metabolic acids is known to produce molecular hydrogen and to stimulate reductive dechlorination.  Concentrations of TCE within and downgradient of the biowall have been reduced within 3 months by an average of 98 percent and 60 percent, respectively.  Concentrations of cDCE have increased in most locations, with no accumulation of vinyl chloride.  Monitoring will continue to determine the long-term ability of the biowall to degrade TCE to innocuous end products.

Ex Situ Bioremediation of Low Concentrations of Perchlorate and Explosives in Groundwater

Katherine R. Weeks, AMEC Earth & Environmental, Inc., 239 Littleton Road, Suite 1B,  Westford, MA  USA 01886, Tel: 978-692-9090, Email: katherine.weeks@amec.com
David L. Hill, National Guard Bureau, Groundwater Program at Camp Edwards, P.B. 565, 567 West Outer Road, Camp Edwards, MA, 02542, Tel: 508-968-5621, Email: David.Hill@MA.ngb.army.mil
Scott C. Veenstra, AMEC Earth & Environmental, Inc., 215 Mistletoe Drive Greensboro, NC USA 27403, Tel: 336-323-1468, Email: scott.veenstra@amec.com

Potential remediation processes for explosives and perchlorate impacted soil and groundwater are being evaluated on a fast track schedule at the Camp Edwards Training Area on the Massachusetts Military Reservation (MMR). Soil and in situ groundwater remediation laboratory treatability studies have been performed since 2000. The most recent round of studies focuses on ex situ remediation of both perchlorate and explosives in groundwater using fluidized bed reactor (FBR), with other processes to be evaluated in the coming year.  Historically, range training operations at Camp Edwards resulted in the deposition onto soil of propellants, explosives, and pyrotechnic (PEP) compounds, some of which have been detected in groundwater.  Perchlorate is present at concentrations ranging from less than 1 to 300 mg/L.  Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is most the commonly detected explosive in groundwater and is present at concentrations ranging from less than 1 to 200 micrograms per liter (mg/L).  The FBR process has been used to degrade relatively high influent perchlorate concentrations at other sites, in the range of milligram per liter in groundwater.  However, Camp Edwards presents different challenges for treatment.  In some operable units at the site, both perchlorate and RDX are present in concentrations of approximately 100 to 200 μg/L.  In other operable units, only perchlorate is present in groundwater, at concentrations below what until recently have been considered as a cleanup standard for many sites of 4 μg/L.  The challenges for the FBR treatability studies were to remediate groundwater in each of these operable units to project goals of less than 1.5 μg/L for perchlorate and to show significant degradation of RDX if it is present.  The challenges have been achieved in two studies.  These laboratory-scale studies are robust enough to provide information to design and implement field-scale applications in the coming year.

Bioremediation of a Railroad Diesel Fuel Spill in Palmer, Massachusetts 

Todd D. Kirton, B.S., Hydrogeologist and Paul G. Beaulieu, M.S., LSP, Tighe & Bond  Consulting Engineers, 53 Southampton Road, Westfield, MA 01085, Tel: 413-562-1600, Fax: 413-562-5317

The nature of the railroad industry nearly ensures the release of petroeum hydrocarbons (in the form of diesel fuel, motor oil, lubricating oils, etc.) to the soils and subsoils along the thousands of miles of rail tracks throughout the United States.  The operation of a locomotive, for obvious reasons, is dependant upon the use of these forms of petroleum hydrocarbons, and leaks, spills and accidents are unavoidable in many cases.  Nevertheless, these releases may be regulated by state environmental agencies.  In Massachusetts, for example, the regulations governing the cleanup of releases of oil and hazardous materials -- the so-called Massachusetts Contingency Plan, 310 CMR 40.000 -- do not exempt the railroad industry from remediating spills in excess of the 10-gallon 'Reportable Quantity'.  Cleanup of spills along active rail lines, however, can be quite challenging.  Rail traffic presents significant dangers to remediation personnel.  Moreover, although excavation of contaminated soils is often the most expediant method for remediating a spill, this option is not always available at sites along active lines, particularly those with no alternative routes, as interruption of rail traffic is not economically acceptable for the rail company or its clientel.  At the 2001 International Conference on Contaminated Soils, Sediments and Water, the authors presented the preliminary results of  a bioremediation program that was implemented at the Palmer Railroad Yard to address the release of 700 gallons of diesel fuel along 1,000 linear feet of railroad tracks.  The initial results of the project were inconclusive, however, in the intervening period additional innoculation, fertilization and wetting of the affected soils has produced a reduction of soil petroleum hydrocarbon concentrations to levels that are less than the regulatory cleanup standards, thereby allowing site closure.  In this paper we will present the details of the additional remediation activities undertaken at the site since 2001 and report on the final analytical results to make the case for using this remediation approach successfully at other active railroad sites.

Top