The New Castle Spill site covers 6 acres in New Castle County, Delaware, where Witco Chemical Company once processed materials for plastic foam production. Chemical spills from drum storage areas contaminated shallow groundwater with tris(3-chloropropyl)phosphate (a flame retardant), volatile organic compounds, polychlorinated biphenyls, creosote, and phthalates. The contamination was serious enough that the local water utility took its shallow aquifer out of service in 1978. About 5,500 people live within three miles of the site in a mixed industrial and residential area.
EPA placed the site on the National Priorities List in September 1983. Witco, as the potentially responsible party, carried out groundwater controls and monitoring while the City of New Castle provided residents with an alternate water supply. EPA and state regulators determined that natural processes could safely reduce contaminant levels over time, since no one in the area was using the shallow aquifer for drinking water. The site was divided into two operable units, with the key cleanup decision covering groundwater monitoring through monitored natural attenuation and institutional controls. Remedial action wrapped up in January 1996, and construction was completed in July 1992.
By 1996, contaminant levels had reached safe levels, and EPA deleted the site from the National Priorities List in June 1996. All four major cleanup milestones have been achieved: human exposure is under control, groundwater migration has stabilized with no unacceptable discharge to surface water, physical construction is complete, and the site is ready for anticipated use. Institutional controls prevent new well installation within a half-mile of the site. EPA continues monitoring to confirm contaminated groundwater stays within the original contamination area.
After cleanup, Witco donated the property and its historic trolley barn to the City of New Castle. The city invested over $700,000 to renovate the barn into office space for its Public Works Department. As of December 2024, three businesses operate on-site, providing 60 jobs. The site is available for unrestricted use and achieved sitewide ready for anticipated reuse status in June 2008.
Community members with questions can contact EPA's Community Involvement Coordinator or Remedial Project Manager directly. Public documents related to the site are available online or in person at the U.S. EPA Region 3 office at 1600 John F. Kennedy Boulevard, Philadelphia, Pennsylvania 19103. Appointments can be scheduled by calling (215) 814-2396.
