Volatile Organic Compounds in the Nation’s Ground Water and Drinking-Water Supply Wells
Mike Moran, USGS, Rapid City, SD

Time Trend Analysis of MtBE Detections in Public Water Systems in Connecticut
Maureen C. Leahy, Environmental Resources Management, East Hartford, CT

Control and Closure of a Rapidly Moving and Diving MTBE/Benzene Plume in a Public Water Supply Area
Michael L. Scherer, Massachusetts Department of Environmental Protection, Bureau of Waste Site Cleanup, Springfield, MA

PM-1 and Beyond:  Assessment of Microbial Degradation of MTBE to Support Re-Injection into Drinking Water Aquifer
Sue Boyle, Haley & Aldrich, Rochester, NY  

Volatile Organic Compounds in the Nation’s Ground Water and Drinking-Water Supply Wells

Mike Moran, Supervisory Hydrologist, U.S. Geological Survey, 1608 Mountain View Road, Rapid City, SD 57702, Tel: (605) 394-3214, Fax: (605) 355-4523, Email: mjmoran@usgs.gov

Personnel from the National Water-Quality Assessment (NAWQA) Program of the United States Geological Survey (USGS) completed a national assessment of the occurrence of 55 volatile organic compounds (VOCs) in 98 aquifers across the United States used as important supplies of drinking water.  The occurrence of VOCs in samples of ground water collected prior to treatment or blending from domestic and public wells also was included.  VOCs were detected in aquifers across the Nation indicating the importance of monitoring the occurrence and trends of VOCs in ground-water resources.  Monitoring of VOCs was performed at low analytical levels in order to fully characterize VOC occurrence.  Twenty-four VOCs warrant further monitoring in ground water resources because they were detected relatively frequently or because they had concentrations greater than, or approaching, Maximum Contaminant Levels (MCLs).  In-depth studies on VOC occurrence in aquifers ultimately could focus on these compounds.  Thirteen VOCs were not detected in any aquifer samples and may not warrant further monitoring in ground water resources.  The detection frequencies of most VOCs were higher in public well samples than domestic well samples.  Less than two percent of samples from domestic or public wells had a VOC concentration of potential human-health concern.  Further studies should investigate the source and transport of VOCs to wells that have VOC concentrations exceeding, or close to, concentrations of potential human-health concern.  Chloroform was the most frequently detected VOC in aquifers and chlorination of drinking water may be an important source of chloroform in ground water.  Methyl tert-butyl ether (MTBE), a gasoline additive, also was one of the most frequently detected VOCs despite its relatively short and recent period of use.  Solvents like PCE and TCE also were frequently detected in ground water and were among the VOCs that most frequently had concentrations greater than MCLs.  Some factors important to the occurrence of VOCs in aquifers included urban land use, septic systems, wet and dry climates, and dissolved oxygen.  The natural and anthropogenic factors that explain the occurrence of a specific VOC in a particular aquifer need to be understood to effectively manage and protect aquifers.

Time Trend Analysis of MtBE Detections in Public Water Systems in Connecticut

Maureen C. Leahy, Environmental Resources Management, 77 Hartland Street, Suite 300, East Hartford, CT, 06108, Tel: 860-466-8500, Fax: 860-466-8501, Email: Maureen.Leahy@erm.com

Methyl-tert-butyl ether (MtBE) was first reported detected in groundwater in Connecticut in 1987.  By February 2000, Connecticut Department of Environmental Protection reported that MtBE had been detected in 4 public water supply wells at concentrations exceeding the State Advisory Level of 70 micrograms per liter (ug/L) and at trace levels in 51 other Public Water Systems (PWS).  In response to the issue of MtBE in groundwater, Connecticut passed legislation in July 2000 to ban the sale and use of MtBE in gasoline.  The ban became effective on 1 January 2004.  Time trend analyses were conducted on monitoring data published by CTDEP to assess the overall effect of the ban on the detection of MtBE in PWS.  Prior to the MtBE ban between 2000 and 2003, 208 PWS in Connecticut had reported the detection of MtBE at least once.  Most of these PWS only reported the detection of MtBE in one reporting year with 60 to 114 PWS reporting MtBE detections annually.  The majority of these detections were less than 3 ug/L and less than 20 of the PWS had reported the detection of MtBE above the State Action Limit.  In the first reporting year after the MtBE ban in 2004,104 PWS reported MtBE detections.  One year later, however, in 2005, the number of PWS reporting MtBE detections dropped to 54.  Of the PWS that reported MtBE for the first time after the ban, only 5 PWS in 2004 and 1 PWS in 2005 reported the detection of MtBE at a concentration greater than the State Advisory Level.  These data indicate a significant decrease in the frequency and magnitude of MtBE detections in Connecticut’s groundwater within two years after the ban.

PM-1 and Beyond:  Assessment of MTBE Biodegradation to Support Re-Injection into Drinking Water Aquifer

Susan L. Boyle, Haley & Aldrich, Inc., 200 Town Center Drive, Rochester, NY 14623, Tel: 589-321-4222, Fax: 585-359-4650, Email: SBoyle@HaleyAldrich.com
Jeffrey M. Baker, Tesoro Petroleum Companies, Inc., 3450 South 344^th Way, Ste 201, Auburn, Washington, 98001-5931, Tel: 253-896-8708, Fax: 253-896-8863, Email: JBaker@tsocorp.com
Kristin Hicks, UC-Davis, 1 Shields Ave, Davis, CA, 95616, Tel: 530-752-0146, Fax: 530-752-1552, Email: Hicks.Kristin@gmail.com
Kate Scow, UC-Davis – Department of Land, Air and Water Resource, 3236 Plant Environmental Science Building, 1 Shields Ave, Davis, CA, 95616, Tel: 530-752-4632, Fax: 530-752-1552, Email: KMScow@ucdavis.edu

This presentation will discuss the regulatory acceptance of a precedent-setting MTBE cleanup program involving re-injection of biologically treated groundwater into an important drinking water aquifer.  The Former Fast Fuel Facility project in North Hollywood, California will be presented as a case study.  Significant microbial analysis of the degradation potential of the aquifer have been performed by the University of California at Davis to support this project.  These microbial evaluations and the role they played in gaining the regulatory acceptance for the overall remediation program will be highlighted. 

The Former Fast Fuel Facility project exhibits successful treatment of a MTBE groundwater plume with a combination of ex-situ biological treatment and re-injection of treated groundwater back into the aquifer.   This site presented significant challenges including: >10 mg/L MTBE in groundwater at over 200 feet below ground surface, high permeability aquifer with dynamic flow conditions, a disconnected plume located beneath a densely populated/developed residential neighborhood, over 70 water supply wells within a 1-1/2 mile radius of the site, and a plume traveling toward the closest municipal supply wells (less than 1,000 feet away) at a rate of approximately 100 feet per year.

The specifics of the ex-situ biological system will be discussed, focusing on the self-seeding of the treatment beds by the bacterial population naturally present in site groundwater.  UC-Davis provided significant support to the project team by assessing the MTBE-degrading characteristics of the indigenous microbial population both in-situ and within the ex-situ treatment beds.  Significant scientific advances were attained during the study that evaluated the adaptations of the microbes to the ex-situ environment and the improvement of the MTBE-degrading kinetics.

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