NEW CASSEL/HICKSVILLE GROUND WATER CONTAMINATION

As of May 2026, the New Cassel/Hicksville Ground Water Contamination Superfund site is considered “Insufficient Data to make a Human Exposure evaluation” (HEID). This status does not necessarily mean that unacceptable exposures are occurring. The site consists of contaminated groundwater near industrial areas in Hicksville, New Cassel, Westbury, Hempstead, and Salisbury, New York. EPA confirmed elevated volatile organic compounds (VOCs)—including tetrachloroethylene (PCE), trichloroethylene (TCE), cis‑1,2‑dichloroethene (cis‑1,2‑DCE), and vinyl chloride—in 11 public water supply wells (six in Hicksville, four in Hempstead, and one in Westbury). New York State is addressing the source areas, while EPA is addressing the large area‑wide groundwater plumes from those sources. The public water supply is treated, so no one is currently drinking contaminated water. However, because investigations and risk assessments for several portions of the groundwater plumes are still underway, there is not yet enough information to determine whether actual or reasonably anticipated human exposures are occurring above acceptable risk‑based levels across all areas and pathways.

Planned activities to collect sufficient information include completing ongoing Remedial Investigation/Feasibility Study (RI/FS) work for the remaining plume areas; installing and sampling additional monitoring wells to delineate plume extent and migration; continuing coordinated sampling with public water suppliers; and preparing Human Health Risk Assessments (HHRAs) for all plume areas to evaluate potential exposure pathways (for example, use of public or private wells, and, where buildings overlie the plume, possible vapor intrusion). EPA will use the RI/FS and HHRA results to support the Human Exposure determination and to inform any additional cleanup decisions. While EPA has already selected a remedy for two areas of groundwater contamination, investigations and risk assessments for other portions remain in progress.

EPA currently anticipates there will be sufficient data to make a Human Exposure determination by March 2028 because groundwater plume delineation and the remaining HHRAs are expected to be completed by that time, providing the information needed to evaluate exposure across all areas.

If you live or work near the site, you can reduce your exposure by continuing to use public water, following any notices from your water supplier, and allowing access for sampling if requested. If you use a private well, test your water before use and follow local health guidance. For more information, contact the EPA Community Involvement Coordinator Joel Waddell via the site webpage or at (212) 637-3590 or [email protected]. EPA will continue to meet with residents and stakeholders, issue public notices and updated fact sheets, and keep the site profile on EPA’s website up to date.