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The Brewster Well Field site is located in Brewster, New York. Volatile organic compounds (VOCs) were found in the village of Brewster’s well field water distribution system in 1978. VOCs are potentially harmful contaminants that easily evaporate in the air. Subsequent testing revealed a large plume of groundwater contamination. EPA traced the source of the contamination to a dry cleaner. Operators disposed of dry cleaning wastes in a dry well next to the business until 1983. Between 1978 and 1984, the Village of Brewster used several new well drilling, blending and pumping strategies to keep contaminant levels down. In 1984, the village partnered with EPA to put in a treatment system. The goal was to remove the VOCs and provide safe drinking water to about 2,000 area residents.

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What Has Been Done to Clean Up the Site?

Five-year reviews are conducted at sites to ensure that the implemented remedies protect public health and the environment and that they function as intended by the site decision documents. EPA’s first five-year review of the site’s cleanup in 2002 found that response actions at the site were protective of human health and the environment. EPA’s second five-year review in 2007 found that additional data was needed before a protectiveness determination could be made. Based on the data collected, EPA completed an addendum to the second five-year review in September 2009. The addendum concluded that the remedy was protective of human health and the environment. The results of soil gas samples collected beneath the slab of the former dry cleaner, which is now a Subaru dealership, showed elevated VOC concentrations. Because of concerns that vapors could be affecting indoor air at the dealership, a subslab mitigation system was installed. Further investigation at the dealership indicated that there was a small volume of contaminated soil under the building. The subslab mitigation system was enhanced so that it could target the contaminated soil. The results of soil sampling in July 2011 indicated that the soil under the building had met the soil cleanup objectives.

There are no impacted private water supply wells near the ground water plume.  Because new wells require a permit from the County’s health department, this effectively prevents their installation near the ground water plume. To prevent potential exposures to contaminated soils below the water table on the Subaru dealership property and to area groundwater, EPA notified the local planning board that EPA should be contacted prior to the approval of any construction on the dealership property and any planned development near the site. EPA also notified the dealership. Periodic reminders are issued to the planning board and the dealership. The County health department’s restrictions related to the installation of wells and the notifications to the planning board and the dealership were added to the implemented remedy. EPA documented these changes in an October 2009 ESD.

In April 2012, EPA issued a five-year review report that concluded that the remedy is protective of human health and the environment in the short-term, because the vapor mitigation system is preventing exposure to contaminated vapors and area-wide well drilling bans and use of a treated municipal water supply prevent exposure to contaminated groundwater. For the remedy to be protective in the long term, the extent of the VOC plume needs to be delineated and alternatives to address plume containment and restoration need to be evaluated.  This effort is underway and is expected to be completed in 2018.

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What Is the Current Site Status?

EPA added the site to the Superfund program’s National Priorities List in 1983. The site is being addressed in two long-term remedial phases focused on cleaning up groundwater and controlling the source of contamination.

Groundwater: The State began a remedial investigation and feasibility study (RI/FS) to determine the nature and extent of the groundwater contamination and to evaluate remedial alternatives in 1984.  On the basis of the State's study, EPA selected a remedy for the ground water in 1986 that included continuing to operate the existing air stripping system at the well field and designing and constructing a ground water management system that would contain the plume of contamination and restore ground water quality in the vicinity of the site by extracting the contaminated ground water from wells, treating the extracted ground water with an air stripper, and reinjecting the treated water into the ground.

In 1991, after the ground water management system became operational, the reinjection wells began to clog. EPA determined the most appropriate approach would be to discharge the treated ground water to the East Branch of the Croton River instead of reinjecting it. Construction of an underground discharge pipe and outfall system for the ground water management system finished in September 1996. The system was restarted in October 1996 and remains in operation. The modification to the selected remedy (i.e., changing the final disposition of the treated groundwater from reinjection to surface water discharge) was documented in a December 1996 Explanation of Significant Differences (ESD). After operating the ground water management system for 10 years as a long-term response action, in October 2007, the State assumed responsibility for its operation and maintenance. To date, it has treated about 357 million gallons of contaminated ground water. EPA estimates that the system will treat 10 million gallons of contaminated groundwater each year for 10 more years.

Source Control: In 1988, following the completion of a source control RI/FS, EPA selected a remedy for cleaning up the source of the ground-water contamination that included excavating about 100 cubic yards of sediments, sludge, and soil contaminated with VOCs from the dry well located outside of the dry cleaners; treating/disposing of these materials off-site; removing the dry well and decontaminating the excavated dry well and associated debris and disposing of them off-site at an EPA-approved hazardous waste facility.  EPA began these cleanup activities in 1989 and completed them in 1991.

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