Millsboro TCE

Overview

The Millsboro TCE site sits in Millsboro, Delaware, and is proposed for the National Priorities List (NPL), the federal government's roster of contaminated sites requiring serious cleanup attention. Trichloroethylene (TCE), an industrial solvent, reached the town's groundwater from poultry vaccine manufacturing operations that ran at the corner of Wharton Street and S. DuPont Highway from 1952 through 1999. State officials first detected TCE above the national drinking water standard in October 2005. No contaminants have been found in private wells or in public water after treatment.

The cleanup has moved through several stages. In 2006, the Delaware Department of Natural Resources and Environmental Control removed about 209 tons of contaminated soil, tanks, and pipes from the source property. The U.S. Environmental Protection Agency (EPA) and three responsible parties signed agreements covering water testing and filter replacement. Public water supply wells were fitted with granulated activated carbon filters. A vapor intrusion assessment, which checks whether underground vapors enter buildings, found no risk, so no further action is needed on that front. In January 2017, EPA chose a remedy combining chemical oxidation of the source area, groundwater pump and treat systems, and long-term monitoring. Removal actions under EPA oversight have taken place across several phases, with one still ongoing as of the most recent reporting period.

Currently, human exposure is under control and contaminated groundwater has been stabilized in its original area. The Town of Millsboro continues filtering groundwater and running weekly drinking water tests, with no detectable TCE found in results. Physical construction of the cleanup is not yet complete, and additional actions remain necessary before the site is considered fully addressed. The potentially responsible party (PRP) carries out cleanup work under EPA oversight and is also evaluating whether vapor intrusion checks are needed for any new buildings near the site.

Community members can stay involved by reviewing fact sheets, public notices, and the Community Involvement Plan that EPA has prepared for this site. Administrative records are available at the Millsboro Public Library at 217 W. State Street (call 302-934-8743 to schedule a visit) and at the EPA Region 3 office at 1600 John F. Kennedy Boulevard in Philadelphia (call 215-814-2396 for an appointment).