EPA Superfund Site

OLD WILMINGTON ROAD GW CONTAMINATION

PA | EPA ID PAD981938939

About this site’s exposure pathways: As of April 2026, the Old Wilmington Road Groundwater Contamination Superfund Site is considered “Insufficient Data to make a Human Exposure evaluation” (HEID) because of a newly identified exposure pathway and/or contaminant(s). The groundwater is contaminated with interconnected plumes of volatile organic compounds, specifically tetrachloroethene (PCE), trichloroethene (TCE), and 1,4-dioxane. Various inorganic contaminants are also present in the groundwater. Recently perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) were added to the list of Site-related contaminants of concern (COCs) in residential drinking water. The human exposure pathway for PFOA/PFOS is defined by the contaminated groundwater used as drinking water. Prior to the discovery of PFOA/PFOS, the site was previously categorized as "Human Exposure Under Control" (HEUC) because those properties impacted by the contaminated groundwater had filtration systems installed on their properties to treat their drinking water for VOCs. The prior HEUC determination was based on filtration systems designed to address VOCs. EPA has evaluated whether these systems effectively remove PFOA and PFOS and whether the existing remedy remains protective; however, additional homes must be sampled to determine the extent of the PFOA/PFOS contamination, which causes the prior HEUC determination to be under evaluation.

EPA uses this Human Exposure status when there is a lack of evidence to suggest that actual or reasonably anticipated human exposures are occurring and that those exposures are above acceptable risk-based levels. The planned activities to collect sufficient information to evaluate these new contaminants are sampling for PFOA/PFOS in groundwater from existing and new monitoring wells, as well as sampling residential drinking water wells for PFOA/PFOS as part of Operable Unit 1 (OU-1). EPA currently anticipates that there will be sufficient data to make a Human Exposure evaluation by October 2027 because EPA plans to complete residential sampling by Q2 2026, receive validated laboratory results by Q3 2026, and complete data evaluation and risk assessment by mid‑2027.

In addition, the sampling being conducted by EPA will inform whether the selected remedy for OU-1, which includes a new public waterline currently in the design phase, needs to be farther expanded to ensure protection of human health and the environment. Filtration systems previously installed to treat drinking water at impacted properties continue to operate as intended and some impacted properties continue to receive bottled water provided by the State.