Electrolytic Aeration of Anoxic Groundwater- A Lab Scale Study and Modeling of the Process 
Ramesh K. Goel, University of South Carolina, Columbia, SC
Lubo Liu, University of South Carolina, Columbia, SC
Joseph R.V. Flora, University of South Carolina, Columbia, SC
Dr. Michael E. Meadows, University of South Carolina, Columbia, SC  

Evaluation of Aerobic Degradation of Pentachlorophenol in Groundwater Using ORC^TM
Paul A. Landin, CH2M HILL, Virginia Beach, VA
Scott J. MacEwen, CH2M HILL, Herndon, VA
Dawn M. Hayes, Commander, LANTNAVFACENGCOM, Norfolk, VA

Eleven Years of Permeable Reactive Barrier (PRB) Technology for the Remediation of VOC Contaminated Groundwater
Stephanie O'Hannesin, EnviroMetal Technologies, Inc., Waterloo, ON, Canada

Containing the Blob: Treatment of Groundwater Contaminated with Coal Tar, Naphthalene, Methyl Naphthalene, Benzene and other Associated Contaminants
Brian Butters, Purifics Environmental Technologies, Inc., London, ON, Canada
Tony Powell, Purifics Environmental Technologies, Inc., London, ON, Canada  

Remediation of Perchlorate-Contaminated Groundwater and Soil at Naval Weapons Industrial Reserve Plant (NWIRP) McGregor, Texas
Ronnie Britto, EnSafe Inc., Memphis, TN
Dan Cowan, EnSafe Inc., Memphis, TN
Mark Craig, Southern Division, Naval Facilities Engineering Command, North Charleston, SC
Alan Jacobs, EnSafe Inc., Memphis, TN
Michael Perlmutter, EnSafe Inc., Memphis, TN

Optimization of Air Sparge Treatment System - Proven Practical Measures
Mary B. Hayes, ENSR International, Westford, MA
Dennis Rentschler, ENSR International, Westford, MA
Kevin Whitney, ENSR International, Westford, MA

Evaluating the Success of Groundwater and Soil Cleanup at Sites Impacted by Fuel Oxygenates
Maryline C. Laugier, Malcolm Pirnie, Inc., Emeryville, CA
Rula A. Deeb, Ph.D., Malcolm Pirnie, Inc., Emeryville, CA
Michael C. Kavanaugh, Ph.D., P.E., Malcolm Pirnie, Inc., Emeryville, CA

Electrolytic Aeration of Anoxic Groundwater- A Lab Scale Study and Modeling of the Process

Ramesh K. Goel, Graduate Student, University of South Carolina, Dept of Civil & Environmental Eng, 300 Main Street, Columbia, SC 29208, Tel: 803-777-7404, Fax: 803-777-0670, Email: goel@engr.sc.edu
Lubo Liu, Graduate Student, University of South Carolina, Dept of Civil & Environmental Eng, 300 Main Street, Columbia, SC 29208, Tel: 803-777-0662, Fax: 803-777-0670, Email: liul@engr.sc.edu
Dr. Joseph Flora, Associate Professor, University of South Carolina, Dept of Civil & Environmental Eng, 300 Main Street, Columbia, SC 29208, Tel: 803-777-8954, Fax: 803-777-0670, Email: flora@engr.sc.edu
Dr. Michael E. Meadows, Associate Professor, University of South Carolina, Dept of Civil & Environmental Eng, 300 Main Street, Columbia, SC 29208, Tel: 803-777-3826, Fax: 803-777-0670, Email: meadows@engr.sc.edu

Bioremediation is at the foremost of a larger group of innovative remediation technologies being applied at hazardous waste sites worldwide.  During its application, this process may require the addition of nutrients and/or electron acceptors to stimulate appropriate biological activity.  For aerobic degradation, oxygen must be available for indigenous microorganisms as a terminal electron acceptor.  The most common means of increasing the dissolved oxygen content of groundwater used in situ bioremediation are injection of air, liquid air and hydrogen peroxide.  The research investigated the electrolytic method of aerating anoxic groundwater to enhance in situ bioremediation by indigenous microbes. Experiments were performed in 7.25 ft x 2.75 ft wide x 1.75 ft deep horse feeding troughs.  The soil used in this study was collected from one onf the South Carolina Electric and Gas Company's gas filling stations, which was reported to be contaminate with PAHs  and had high amounts of ferrous iron.  In lab experiments, tap water was used and sodium sulfite was used to deoxygenate water to create anoxic environment in the tanks.  Doses of sodium sulfite used were in excess to those obtained by stochiometry required to react with dissolved oxygen.  Experiments were also performed with oxygen releasing compounds (ORC), a commercially available technology for aerating anoxic groundwater.   This was done to compare results with electrolytic aeration technique and to check the viability of electrolytic aeration.  The results obtained so far show that electrolytic aeration of the groundwater with 100 mA electric current is possible and the method is very much competitive with ORC technology.  Dissolced oxygen level as high as 2-3 mg/l were obtained in the well located 2-3 feet downstream of oxygen producing well.  In on going study, we are in the porcess of developing a numerical, which will predict oxygen transport under the conditions used during actual lab scale experiments.  Based on the experimental setup, a two-dimensional mathmatical model will be developed to simulate and evaluate oxygen generation in the tanks.  The physical parameters required for the model were measured in situ.  The first-order rate constants describing the consumption of sodium sulfite and oxygen generation were obtained by fitting the model to the tank data.  With these parameters, the model will be subsequently used to predict the performance of the electrolytic cell in contributing to DO levels downstream of electrolytic probe well.

Evaluation of Aerobic Degradation of Pentachlorophenol in Groundwater Using ORC^TM

Paul A. Landin, CH2M HILL, 5700 Thurston Avenue, Suite 120, Virginia Beach, VA 23455, Tel: 757-460-3734, x12, Fax: 757-460-4592
Scott J. MacEwen, CH2M HILL, 13921 Park Center Road, Suite 600, Herndon, VA 20171, Tel: 703-471-1441, x 4332, Fax: 703-471-1508
Dawn M. Hayes, Commander, LANTNAVFACENGCOM, Code: EV-22DMH, 1510 Gilbert Street, Norfolk, VA 23511, Tel: 757-322-4792, Fax: 757-322-4805

A pilot study using Oxygen Releasing Compound (ORC^TM ) has been recently completed to evaluate its effects on pentachlorophenol (PCP) in groundwater at a CERCLA facility in Virginia Beach, Virginia. The site is a former PCP wood treatment dip tank at a military installation where past operations resulted in releases of PCP and diesel fuel to the surrounding soil and water table aquifer. The study was conducted over a period of seventeen months, which included the installation of groundwater monitoring wells, collection of baseline groundwater samples, injection of ORC^TM slurry into the surficial aquifer, and post-injection groundwater monitoring.

Approximately 1,400 pounds of ORC^TM were injected into the groundwater over the 750 square foot area where the dip tank was formerly located. The injection was completed using direct-push (GeoprobeÒ ) methods and included the entire 17 foot interval (6 to 23 feet bgs) within the surficial aquifer. The contaminated soil above the water table had been excavated prior to the pilot test. Groundwater monitoring was performed at up-gradient, injection area, and down-gradient monitoring wells at six periodic intervals for fifteen months after the injection. Monitoring parameters included semivolatile organic compounds, metals, ferrous iron, chloride, carbon dioxide, and alkalinity, in addition to standard field parameters. Results of groundwater monitoring show an average PCP degradation of 92% in the four monitoring wells that  demonstrated the highest initial concentrations.  Remaining maximum concentrations of PCP are approximately 100 mg/L and minimum concentrations are at or below the laboratory detection limit of approximately 20 mg/L. PCP concentrations in these wells continue to decline with each round, and dissolved oxygen concentrations in these same monitoring wells remain elevated over baseline conditions by an average of 216%, after 15 months of monitoring. Therefore, the ORC^TM appears to be further degrading PCP at the completion of the pilot study.

Eleven Years of Permeable Reactive Barrier (PRB) Technology for the Remediation of VOC Contaminated Groundwater

Stephanie O’Hannesin, EnviroMetal Technologies Inc., 745 Bridge Street West, Suite 7, Waterloo, Ontario, Canada  N2V 2G6 Tel:  519-746-2204, Fax:  519-746-2209, Email:  sohannesin@eti.ca

In the eleven years since the initial research-scale granular iron permeable reactive barrier (PRB) was installed to remediate volatile organic compounds (VOCs) in groundwater, the technology has been applied around the globe, with installations in North America, Europe, Australia and Japan.  In varying geologies and geochemical conditions, the technology has proven to be very robust.  To date, no site has required rehabilitation, confirming that PRB technologies represent a predictable, long term-treatment solution in most hydrogeologic environments.

The initial capital costs to install VOC PRB systems are typically equivalent to those costs associated with installing a pump-and-treat (P&T) system, and  PRB technology offers significant cost savings due to the very low, long-term operating and maintenance costs.  When comparing costs using a net present value analysis for the life cycle of these systems, the cost savings for these PRB systems far surpass those of P&T.  Another benefit is that granular iron PRB system completely destroy VOCs, as opposed to P&T where the contaminants are simply transferred to the another medium, such as the atmosphere, or to granular activated carbon which requires further disposal or regeneration.

Over the past decade, the cost to install these PRB systems have decreased dramatically, as the costs of granular iron have been reduced by over 50% and as contractors have become more familiar with PRB installations and have developed cost effective installation methods.  The influence of key design parameters such as groundwater velocity variation have been incorporated into the PRB design improving the effectiveness of the technology.  PRB systems are remediating sites and bringing closure for many site owners.

Containing the Blob: Treatment of Groundwater Contaminated with Coal Tar, Naphthalene, Methyl Naphthalene, Benzene and other Associated Contaminants

Brian Butters, Purifics Environmental Technologies Inc., 1941 Mallard Road, London, Ontario, N6H 5M1, Canada, Tel: 519-473-5788, Fax: 519-473-0934, Email: brian.butters@purifics.com
Tony Powell , Purifics Environmental Technologies Inc., 1941 Mallard Road, London, Ontario, N6H 5M1, Canada, Tel: 519-473-5788, Fax: 519-473-0934, Email: tony.powell@purifics.com

On a bank of the Thames River in London, Ontario, Canada, an 18^th century coal gas generating station disposed of its coal tar in onsite pits.  About a decade ago, area residents noted an oily slick (quickly dubbed “The Blob”) flowing downstream of the site.  It was determined that groundwater was carrying the coal tar into the river.  Remedial action consisting of a clay barrier and collection trench succeeded in containing the contamination.  The PRP investigated a conventional pump and treat treatment train, involving flocculation, filtration, organo-clay and carbon to capture and remove the contaminants pumped out with the groundwater.  Upon further analysis, Purifics^â’ Photo-Cat^â system, based on titanium dioxide photocatalytic technology, was chosen as the most effective and lower cost alternative.  This paper will review the decision-making process involved in selecting the Photo-Cat^â system, the operating and maintenance costs of the first operational year, the science behind the photocatalytic process and the Photo-Cat^â’s success in destroying the contaminants.

Remediation of Perchlorate-Contaminated Groundwater and Soil at Naval Weapons Industrial Reserve Plant (NWIRP) McGregor, Texas

Ronnie Britto, EnSafe Inc., 5724 Summer Trees Drive, Memphis, TN 38134, Tel: 901-372-7962, Fax: 901-372-2454
Dan Cowan, EnSafe Inc., 5724 Summer Trees Drive, Memphis, TN 38134, Tel: 901-372-7962, Fax: 901-372-2454
Mark Craig, Southern Division, Naval Facilities Engineering Command, 2155 Eagle Drive, North Charleston, SC 29418, Tel: 843-820-5517, Fax: 843-820-5563
Alan Jacobs, EnSafe Inc., 5724 Summer Trees Drive, Memphis, TN 38134, Tel: 901-372-7962, Fax: 901-372-2454
Michael Perlmutter, EnSafe Inc., 5724 Summer Trees Drive, Memphis, TN 38134, Tel: 901-372-7962, Fax: 901-372-2454

Beginning in 1999, interim stabilization measures were implemented to abate offsite migration of perchlorate ¾ a chemical that was just surfacing as an environmental pollutant with significant health implications ¾ from NWIRP McGregor.  The Navy targeted perchlorate-contaminated groundwater that was exfiltrating to surface water before migrating offsite, source area groundwater, and impacted surface soils.  In three years, the Navy mitigated offsite perchlorate migration by rapidly and effectively developing perchlorate treatment technologies from conception through bench and pilot scale testing to full-scale implementation. 

The Navy installed trenches to cutoff and intercept groundwater before it surfaced via springs and seeps.  The trenches also effectively served as PRBs that fostered anaerobic zones using in place natural organic media and supplemental soluble carbon sources.  Perchlorate concentrations in groundwater were biologically reduced from 20 to <0.004 mg/L using in situ techniques.

Ex situ treatment systems, including static- and fluidized-bed bioreactors as well as an ion exchange unit, have also been used effectively to address contaminated water pumped from the collection trenches.  Effluent concentrations have routinely been below detection limits. 

The Navy developed engineered and in situ anaerobic soil treatment systems, which biologically reduced perchlorate concentrations from 1,800 mg/kg to below detection limits.  The in situ soil units also allow amendment-rich water to infiltrate to address source area groundwater and provide polishing for ex situ treatment systems. 

Because of site hydrogeology and seep concerns, the Navy also installed 200 amendment-filled bioborings to passively address offsite groundwater contamination in situ.  Perchlorate concentrations have been reduced by an order of magnitude in the study area.

Next generation PRBs were installed in July 2002 to treat perchlorate- and VOC-contaminated groundwater.  The PRBs included a variety of organic media as well as a multi-purpose piping system to inject/infiltrate additional soluble amendments over time.

The precedent-setting remediation effort at NWIRP McGregor has received regional and national recognition for its environmental achievement.

Optimization of Air Sparge/Soil Vapor Extraction Treatment System  - Proven Practical Measures

Mary B. Hayes, Dennis Rentschler and Kevin Whitney, ENSR International, ENSR International, 2 Technology Park Drive, Westford, MA 01886, Tel: 978-589-3000, Fax: 978-589-3100

This paper describes the optimization measures that ENSR implemented at an air sparging/soil vapor extraction (AS/SVE) system.  In 1998,  ENSR designed, installed and operated an AS/SVE system at a former industrial site in Massachusetts to remediate dissolved toluene in groundwater.  The original system consisted of 100 driven sparge points and 40 SVE wells over 1.5 acres.  Significant mass removal of toluene (> 6,000 lbs.) was achieved within the first year of operation, and a large portion of the site was remediated to below the groundwater standard.  However, groundwater in one area of the site was not  being remediated,  some critical AS points were not working effectively, and field staff experienced difficulties in collecting O&M measurements.  ENSR evaluated the original system design, and implemented the following practical measures to optimize system operation:

• Replacement of driven sparge points with augered wells with a sand pack,

• Replacement of the sparge screen placement in the zone of contamination (not below it), establishing horizontal air flow through more permeable layers,

• Refinement of instruments and sampling ports to allow easier, more consistent measurement of system operation by field staff, and

• Down-sizing and reconfiguring the treatment system to target the area still needing remediation.

System improvements were implemented in 2000 and 2001.  A significant increase in mass removal was observed following each phase of optimization.  Remediation after optimization was achieved with reduced O&M and lower operating costs.  Only one well at the site remains above the groundwater standard.  The demonstrated improvements that ENSR implemented at this site are now used at other AS/SVE treatment systems.

Evaluating the Success of Groundwater and Soil Cleanup at Sites Impacted by Fuel Oxygenates

Maryline Laugier, Malcolm Pirnie, Inc., 2000 Powell Street, Suite 1180, Emeryville, CA 94608, Tel: 510-735-3034, Fax: 510-596-8855, Email: mlaugier@pirnie.com
Rula A. Deeb, Ph.D., Malcolm Pirnie, Inc., 2000 Powell Street, Suite 1180, Emeryville, CA 94608, Tel: 510-735-3005, Fax: 510-596-8855, Email: rdeeb@pirnie.com
Michael C. Kavanaugh, Ph.D., P.E., Malcolm Pirnie, Inc., 2000 Powell Street, Suite 1180, Emeryville, CA 94608, Tel: 510-735-3010, Fax: 510-596-8855, Email: mkavanaough@pirnie.com

Fuel oxygenates are added to gasoline to increase combustion efficiency and to reduce air pollution in order to meet the requirements of the 1990 Clean Air Act Amendments. The most commonly used oxygenate is methyl tert-butyl ether (MTBE). In the United States, the use of MTBE as a gasoline additive started in the late 1970s. Over the past decades, MTBE use has increased significantly. As a result of its widespread usage, reports of environmental contamination by MTBE in the vicinity of Leaking Underground Storage Tanks (LUST) and dispensing equipment have increased as well. Because of its specific physical and chemical properties, MTBE is highly soluble in water, does not strongly sorb to soil particles and strongly partitions into the aqueous phase. As a consequence, MTBE tends to be highly mobile in subsurface environments relative to other gasoline constituents and can potentially migrate at groundwater velocities. Recent reports of MTBE detection in drinking water wells have led environmental managers and regulators to reassess cleanup strategies at MTBE-impacted sites. Concerns have mostly focused on the feasibility of removing MTBE from contaminated groundwater in a cost-effective manner. This work will include a review of the fate and transport of MTBE following accidental releases of MTBE-blended gasoline with an emphasis on the relevance of these fate and transport characteristics on the appropriate strategy to select for cleanup. State of the art information regarding groundwater and soil cleanup at MTBE-impacted sites will be evaluated using recent successful case studies. A short description of the technology used at the site, discussions of the effects of contaminant and site characteristics, evaluation of the technology success and limitations will be presented for each case study. Finally, general cleanup cost estimates will be discussed in an effort to illustrate how the presence of MTBE impacts the costs of remediating gasoline-impacted sites.

Top