Maine's Experiment With Gasoline Policy to Manage MtBE in Groundwater
John M. Peckenham, University of Maine, Orono, ME 
Jonathan Rubin, University of Maine, Orono, ME
Cecilia Clavet, University of Maine, Orono, ME

Assessment, Control and Remediation of a Diving and Rapidly Moving MTBE/Benzene Plume to Prevent Impacts to Down-Gradient Public Water Supply Wells in the Town of Palmer Massachusetts
Michael Scherer, Massachusetts Department of Environmental, Springfield, MA

Electrical Resistance Heating Technology Coupled with Air Sparging and Soil Vapor Extraction for Remediation of MTBE and BTEX in Soils and Groundwater in Ronan, Montana
Jeffrey Kuhn, Montana DEQ, Butte, MT
Kenneth Manchester, MSE Technology Applications, Butte, MT 

Ozone Sparging for In-Situ Oxidation of MTBE
David H. Hull, LFR Levine·Fricke, Granite Bay, CA 
J. Scott Seyfried, LFR Levine·Fricke, Granite Bay, CA 
Steven J. Osborn, Kinder Morgan Energy Partners, Rocklin, CA
Cindy G. Schreier, PRIMA Environmental, Sacramento, CA 

Enhanced In Situ Groundwater Bioremediation of Petroleum Hydrocarbons and Oxygenates – Field Applications and Data Evaluation
Kostas Dovantzis, Handex Group, Inc., Naperville, IL 
Thomas J. Marr, Handex Group, Inc., Mooresville, NC
Tim Foster, Handex Group, Inc., Bethel, CT 
Ray Kassab, Handex Group, Inc., Indianapolis, IN

Methyl tert-Butyl Ether (MTBE) in Public and Private Wells in Southeast New Hampshire

Joseph D. Ayotte, U.S. Geological Survey, 361 Commerce Way, Pembroke, NH 03275, Tel: 603-226-7810, Fax: 603-226-7894, Email: jayotte@usgs.gov
Denise M. Argue, U.S. Geological Survey, 361 Commerce Way, Pembroke, NH 03275, Tel: 603-226-7833, Fax: 603-226-7894, Email: dmargue@usgs.gov
Frederick J. McGarry, New Hampshire Dept. of Environmental Services, Waste Mgmt. Division, 6 Hazen Drive, Concord, NH 03301,             Tel: 603-271-4978, Fax: 603-271-2456, Email: fmcgarry@des.state.nh.us

The occurrence the gasoline oxygenate MTBE (above 0.5 micrograms per liter) in public water supply wells in New Hampshire has increased steadily over the past several years. Occurrence rates increased from 12.7 percent of wells tested in 2000 to 15.1 percent in 2002.  In Rockingham County, where reformulated gasoline (RFG) usage is mandated, the percentage of public wells with MTBE above 0.5 micrograms per liter (mg/L) increased from 20.3 percent in 2000 to 23.1 percent in 2002 based on data from the State of New Hampshire. New data collected from randomly selected wells in Rockingham County indicate that in 2003, 26.2 percent of the public wells had MTBE concentrations that exceeded 0.5 mg/L.  Overall, 40 percent of water samples from public wells and 21 percent from private wells in the County had measurable concentrations of MTBE, based on a low laboratory reporting level of 0.2 mg/L.  Further, MTBE occurrence varied for public wells by type of establishment served; 67 percent of public wells serving residential properties have MTBE concentrations above 0.2 mg/L, whereas lower rates were found for wells serving commercial entities (41%), schools (23%), and large communities (27%).  MTBE concentrations correlated significantly with urban factors, including population density and distance to gasoline underground storage tanks; however, the most significant correlation was with well depth for public supply wells.  Water from deep bedrock public supply wells, had higher MTBE concentrations than shallower bedrock wells. This relation is contrary to the conventional thought that deep bedrock wells are less vulnerable to contamination than shallow wells.  In Rockingham County, where water availability is a major concern, wells are being drilled deeper in search of increased supply.

Maine's Experiment With Gasoline Policy to Manage MtBE in Groundwater

John M. Peckenham, Senator George J. Mitchell Center for Environmental and Watershed Research, University of Maine, 102 Norman Smith Hall, Orono, ME  04469, Tel: 207-581-3254
Jonathan Rubin, Senator Margaret Chase Smith Center for Public Policy, University of Maine, Orono, ME
Cecilia Clavet, Department of Resource Economics and Policy, University of Maine, Orono, ME

The gasoline additive MtBE has become one of the most commonly detected contaminants in groundwater nationwide and has caused much concern in the state of Maine.  In 1998 the Maine Department of Human Services conducted a statewide survey of groundwater wells and MtBE was detected in 16% of private and public wells tested.  These findings resulted in the state regulatory agencies deciding to opt out of the reformulated gasoline (RFG) program in 1999.  Subsequently, the average concentration of MtBE in gasoline dropped from ~15% to 2% by volume to protect water resources.  This major policy change provided a microcosm to study the economic and environmental effects of this gasoline additive. In order to test the effect of this policy on water quality, groundwater samples were analyzed over a period of six years (1998-2003) from 19 wells distributed across a sand and gravel aquifer in Windham, Maine. MtBE continues to occur in detectable concentrations in 30 to 40% of the study wells despite Maine’s decision to opt out of the RFG program in 1999.  Although recent detected concentrations are lower than in previous years, this study confirms MtBE’s temporal and spatial persistence in the environment. Reducing MtBE concentrations in gasoline may not be sufficient to eliminate its occurrence in groundwater.  The economic perspective is that MtBE increases the cost of groundwater remediation, as compared to MtBE-free gasoline. Economic data for spills are being analyzed to assess if reducing MtBE concentration in gasoline has affected remediation cost. Preliminary results suggest that MtBE increases costs, even when present in low concentrations in gasoline. 

Assessment, Control and Remediation of a Diving and Rapidly Moving MTBE/Benzene Plume to Prevent Impacts to Down-Gradient Public Water Supply Wells in the Town of Palmer Massachusetts

Michael Scherer, M.S., Massachusetts Department of Environmental, Western Regional Office, 436 Dwight Street, Springfield, MA  01103, Tel:  413-755-2278, Email:  michael.scherer@state.ma.us

The catastrophic failure of a gasoline tank results in the sudden injection of approximately 12,000 gallons of premium gasoline to the groundwater within the Zone 2 of a public water supply well.  Immediate actions to address the release were not taken by the MADEP due to a substantial delay in notification by the owner.

Initial assessment reports completed for the property owner indicated that the LNAPL area was stable and that the gasoline plume was contained on site.  However, MADEP required that additional monitoring wells be installed at depth and that existing down gradient monitoring wells installed as part of another site investigation involving solvents were also to be sampled for MTBE.   Samples from several of these down gradient monitoring wells installed as part of the MADEP investigation and other pre-existing monitoring wells identified that an MTBE plume had migrated at depth far beyond the original release site.  Monitoring at depth down gradient within the aquifer indicated that MTBE and later Benzene were migrating at a rapid rate deep within the aquifer towards the Town Water District’s active drinking water supply wells, located approximately 500 feet from the leading edge of the plume. 

Initial shallow recovery wells that were installed to recover gasoline in the release area were ineffective in containing the MTBE plume.  Additional recovery wells installed at depth further down gradient proved effective in containing the plume and preventing impacts to the public water supply wells.   After containment of the plume was effected, intensive remedial efforts were undertaken to address the remaining source area by several injections of potassium permanganate solution.  Initial injections of permanganate solution were completed in December 2003.

Electrical Resistance Heating Technology Coupled with Air Sparging and Soil Vapor Extraction for Remediation of MTBE and BTEX in Soils and Groundwater in Ronan, Montana

Jeffrey Kuhn, Montana DEQ, Butte, MT
Kenneth Manchester, MSE Technology Applications, 200 Technology Way, Butte, Montana 59701, Tel: 406-494-7397, Fax: 406-494-7230, E-mail:  kmanch@mse-ta.com

Gasoline from a leaking underground storage tank located in Ronan, Montana contaminated the soil and groundwater with methyl tertiary butyl ether (MTBE), benzene, toluene, ethylbenzene, xylenes (BTEX), and other gasoline compounds. Complete clean-up of the site was made difficult because the contaminant plume extended  beneath Highway 93, a primary highway in the area.  Common remedial technologies such as soil vapor extraction (SVE) and air sparging have been used historically at the site and have been moderately effective in reducing contaminant levels.  To more aggressively remediate the site, specifically a defined volume of soil and groundwater beneath Highway 93, MSE combined traditional air sparging and soil vapor extraction technologies with an innovative electrical resistance heating (ERH) technology.  Twelve air sparging electrodes, six SVE wells, and eight auxiliary air sparge points were placed under the highway. Temperatures in the treatment volume exceeded 100ºC and input power to the electrodes varied between 12 kW and 17 kW for 142 days. Soil and groundwater samples collected from the treatment volume before the demonstration had a significant amount of MTBE and BTEX contamination.  Post groundwater and soil samples had undetectable concentrations of MTBE and BTEX. 

Ozone Sparging for In-Situ Oxidation of MTBE

David H. Hull, RG, LFR Levine·Fricke, 4190 Douglas Boulevard, Suite 200, Granite Bay, CA  95746, Tel:  916-786-5210/0320, Fax: 916-786-0366, Email:  david.hull@lfr.com
J. Scott Seyfried, RG, CHG, LFR Levine·Fricke, 4190 Douglas Boulevard, Suite 200, Granite Bay, CA  95746, Tel:  916-786-0342/0320, Fax: 916-786-0366, Email: scott.seyfried@lfr.com
Steven J. Osborn, Kinder Morgan Energy Partners, L.P., SFPP Rocklin Station, P.O. Box 1318,  Rocklin, CA 95677, Tel: 916-624-2110, Fax: 714-560-6612, Email: osborns@kindermorgan.com
Cindy G. Schreier, PhD, PRIMA Environmental, 10265 Old Placerville Road, Suite 15, Sacramento, CA  95827-3042, Tel: 916-363-8798, Fax: 916-363-8829, Email: Iron@PRIMAEnvironmental.com

Bench-scale and pilot-scale studies were conducted to evaluate the efficacy of ozone sparging for in-situ remediation of methyl tertiary butyl ether (MTBE) and associated petroleum hydrocarbons and fuel oxygenates in shallow groundwater at a petroleum terminal in northern California.

Bench-scale laboratory tests conducted on groundwater and soil from the subject site indicated that MTBE was completely destroyed by oxidation, rather than volatilized, during these tests.  Residual breakdown products of MTBE were limited to transient accumulations of tertiary butyl alcohol (TBA) and acetone, which were subsequently oxidized. These tests required between 20- to 100-times theoretical stoichiometric amounts of ozone in groundwater and groundwater-plus-soil slurry samples, respectively, to completely oxidize MTBE.  The increased ozone demand was attributed to gas-to-liquid phase mass transfer limitations of ozone and to non-target compound oxidant demand.  Application of ozone to slurries of groundwater and soil resulted in oxidation of ferrous iron (Fe⁺²), and increases in total suspended solids related to precipitation and flocculation of dissolved metals, with a mean particle size of approximately 50 microns. 

Based on the successful results of the bench-scale tests, a pilot-scale test was designed and implemented at the subject site.  The pilot test included the injection of an air:ozone mixture into a single sparging well, and completion of monitoring of five surrounding wells for organic and inorganic constituents.  Monitoring was conducted to assess potential effects of iron precipitation on aquifer hydraulic conductivity, and potential formation of target compound breakdown products (i.e., TBA, acetone), bromate, hexavalent chromium, and other redox sensitive metals.  During the one-month pilot test, monitoring wells within 40 feet of the sparge well exhibited MTBE concentration decreases between 76 to 99 percent from pre-test and background conditions, with comparable decreases in other petroleum hydrocarbons and fuel oxygenates.  Only transient increases in TBA were observed, and no other breakdown products were detected.  In addition, bromate was not detected despite the presence of bromide in groundwater, and hexavalent chromium was not detected despite the presence of chromium in groundwater.  While the bench-scale tests indicated that 180 to 900 grams of ozone were required to oxidize one gram of MTBE, pilot test results indicated that only approximately 20 grams of ozone were required to destroy one gram of MTBE.  The lower ozone demand observed during the field test, relative to the bench-scale tests, may be due to excessive ozone demand during intensive mixing of the soil-groundwater slurry sample and ozone loss through the sample column, as well as the potential occurrence of biodegradation resulting from increases in dissolved oxygen in groundwater and the longer duration of the field test.  Finally, no significant changes in aquifer hydraulic conductivity were noted despite the reduction in dissolved ferrous iron and increase in total iron in groundwater.

Enhanced In Situ Groundwater Bioremediation of Petroleum Hydrocarbons and Oxygenates – Field Applications and Data Evaluation

Kostas Dovantzis, Ph.D., P.E., DEE, Corporate Engineering Manager, Handex Group, Inc., 1701 West Quincy Avenue, Suite 10, Naperville, IL  60540, Tel: 630-527-1666, ext. 114, Fax: 630-527-8174, Email: kdovantzis@handexmail.com
Thomas J. Marr, P.G., Vice President Technical Resources, Handex Group, Inc., 113 Charter Place, Mooresville, NC 28117, Tel: 704-799-8731, Fax: 704-799-0643, Email: tmarr@handexmail.com
Tim Foster, Senior Project Manager, Handex Group, Inc., 11 Berkshire Boulevard, Bethel, CT  06801, Tel: 203-798-6100, Fax: 203-798-6240. Email: tfoster@handexmail.com
Ray Kassab, Associate Project Manager, Handex Group, Inc., 6990 Corporate Drive, Indianapolis, IN 46278, Tel: 317-347-1111, Fax: 317-347-9326, Email: rkassab@handexmail.com

Oxygen enrichment in gasoline-impacted groundwater has been shown to enhance intrinsic biodegradation of MTBE and BTEX and accelerate site cleanup.  Oxygen enrichment takes place using a variety of technologies that add air or oxygen directly in groundwater and indirectly using in situ chemical oxidation (ISCO).  Direct addition of oxygen results in higher dissolved oxygen (DO) concentrations than air or ISCO. 

This work presents field experiences from several retail gasoline service stations where direct oxygen addition and ISCO were implemented.  Data are evaluated from sites in New Jersey, Connecticut, New York, and Indiana.  Subsurface soils ranged from silty clays to fine/medium sands.  Oxygen was added directly using diffusive probes or indirectly by injecting a proprietary chemical oxidant blend.  Diffusive probes were installed in 2-inch diameter monitoring wells or were buried directly in the boreholes.  The chemical oxidant was injected using a Geoprobe™.

Prior to system startup or chemical injection, baseline groundwater samples were collected for MTBE, BTEX, BOD, COD, TOC, nitrogen, phosphorus, and ferrous iron analysis.  Baseline DO levels were also measured.  After oxygen addition or chemical injection, groundwater samples were collected periodically for analysis of the above parameters.  Monitoring wells were located and screened so as to provide data necessary for remedial action performance evaluation.  

Shortly after oxygen addition or chemical injection, DO levels increased to 50 to 60 mg/L at sites where diffusive probes were used and 10 to 15 mg/L where chemical oxidation took place.  DO influence downgradient and sidegradient from oxygen infusion wells occurred within two months from startup.  BTEX reductions over 99 percent and MTBE reductions over 98 percent were documented in several wells within one quarter following oxygen addition.  Chemical injection temporarily mobilized residual soil hydrocarbons with subsequent temporary increase in product thickness and dissolved phase BTEX concentrations.  Product thickness and dissolved concentrations declined over time.    

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