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U.S. Environmental Protection Agency

Missouri Water Science Center

Expanded Site Inspection (ESI)

The following is a brief description of the Expanded Site Investigation (ESI), a printed copy of the report is available at the Riverfront Site Data Repository located at the New Haven Public Library.

An expanded site investigation (ESI) of what was then called the New Haven Public Water Supply Site was conducted by the the U.S. Environmental Protection Agency (EPA). The purpose of the ESI was to identify the source(s) of tetrachloroethene (PCE) contamination in the public drinking water supply wells, to collect analytical data and provide an estimate of the source waste quantity (amount of PCE waste) to be used in Hazard Ranking System (HRS) scoring for the site.

The ESI included a review and compilation of all existing data, a discussion of the hydrogeology of the New Haven area from published reports, and the collection of shallow [less than 10 ft (feet) deep] subsurface soil samples from the Riverfront site. Several locations where PCE potentially was used and disposed of were identified in the ESI.  These locations included the Riverfront site, the city dump, a former dry cleaner, and an industrial facility in the southern part of the city. The ESI concluded that the Riverfront site in downtown New Haven was the most likely source of the PCE contamination detected in city wells W1 and W2. The Riverfront site is less than 700 ft from city well W2 and subsurface soil samples contained PCE concentrations as large as 83,000 ug/kg (micrograms per kilogram). A site in the southern part of the city where PCE was known to have been disposed of on the land surface was not considered a likely source because it was thought to lie south of an inferred shallow ground-water divide. The contaminated city wells (W1 and W2) were thought to lie north of the inferred shallow ground-water divide. However, concentrations of PCE as large as 810,000 ug/kg had been detected in soil samples from the facility to the south. The city dump was not considered a likely source because it is nearly 1 mi (mile) from the contaminated city wells, and large PCE concentrations have not been detected in previous samples from the site.

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