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The New Cassel/Hicksville Ground Water Contamination site (Site) is an area of widespread groundwater contamination in the Town of North Hempstead, Hempstead and Oyster Bay in Nassau County, New York. In 2010, EPA sampling found contaminants in the pre-treated water from four Town of Hempstead wells, six Hamlet of Hicksville wells and one Village of Westbury well. The primary contaminants observed in groundwater at the Site are tetrachloroethylene (PCE), trichloroethylene (TCE) and other volatile organic compounds (VOCs). VOCs are contaminants that evaporate easily into the air and dissolve in water. VOCs are often used as ingredients in paints, solvents, aerosol sprays, cleaners, disinfectants, automotive products and dry cleaning fluids. Past industrial and commercial activities in the area may have contributed to the groundwater contamination at the site. Consistent with the Safe Drinking Water Act that protects public drinking water supplies throughout the nation, the public water suppliers in the area of the Site monitor water quality regularly and have previously installed treatment systems to remove VOCs from groundwater.

From 1988 to 2010, the New York State Department of Environmental Conservation (NYSDEC) identified a number of sources of the contamination and further investigated the contaminated groundwater pursuant to New York State authorities.  In 2010, NYSDEC requested that EPA list the Site on the Superfund Program’s National Priorities List (NPL).  The Site was listed on the NPL in September 2011. EPA is addressing the Site in discrete phases or components known as operable units or OUs. After the Site’s NPL listing, site investigations to determine the nature and extent of contamination and to identify and evaluate remedial alternatives were conducted.

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What Has Been Done to Clean Up the Site?

The Site is a widespread area of groundwater contamination in Hempstead, Hicksville and Westbury. Residents of this area receive drinking water from public water supplies that have installed treatment systems to meet drinking water standards and thus supply water that meets these standards.

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What Is the Current Site Status?

Operable Unit 1: EPA finalized selection of the remedy to cleanup contaminated groundwater in a September 2013 Record of Decision (ROD). As a next step, the selected remedy in the OU1 ROD, will be designed. It is anticipated that as part of the remedial design, additional data to support design of the remedy will be collected. After completion of the remedial design, the remedial action (the cleanup) will be implemented. EPA expects that the parties responsible for the contamination, also known as potentially responsible parties (PRPs) will conduct or pay for the design and ultimately implementation of the remedy.

Operable Unit 2: The RI is ongoing. After completion of the RI/FS, a proposed cleanup plan will be released for public comment.

Operable Unit 3: EPA is currently conducting a RI for OU3. Field activities began in spring of 2017 in the Salisbury area, north of the Eisenhower Park Gold Course. The primary objective of the OU3 investigation is to horizontally and vertically delineate the nature and extent of groundwater contamination in the underlying aquifers. Based on the limited existing groundwater data within the area, a phased approach is being used to improve the understanding of groundwater contamination in OU3. Under this approach, three vertical profile borings, which are investigative borings drilled for collection of samples at various depths, were drilled to a maximum depth of approximately 600 feet below grade surface as part of Phase 1. The purpose of the borings was to document hydrogeological conditions and collect groundwater samples from discrete aquifer intervals to assess the vertical extent of volatile organic compound (VOC) contamination. Information from the borings was used to target the installation of one or two (shallow or deep) permanent monitoring wells at each location. Based on the findings from this initial phase, three additional borings were targeted for installation as part of Phase 2. Following the permanent groundwater well installation, groundwater samples were collected from the newly installed monitoring wells for VOCs, semi-volatile organic compounds, pesticides and metals analysis. Results of the analyses will assist in the characterization (i.e., nature and extent) of the impacted groundwater and will be used for planning the next steps of the investigation. Additional sampling is needed at these newly installed wells, as well as other existing wells in the vicinity of OU3 in order to fully characterize groundwater conditions in the area. This work is ongoing.

Following the OU3 investigation, a RI report will be prepared to document the investigation activities and results. A separate FS report will also be prepared to present cleanup alternatives that may be implemented to address the impacted groundwater. Upon completion of the RI/FS, EPA will issue a plan for public comment which selects our preferred method of cleanup.

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