The Willow Grove Naval Air and Air Reserve Station sits on roughly 1,100 acres in Montgomery County, Pennsylvania. It includes a roughly 900-acre former Navy facility that closed in 2011 and an adjacent roughly 200-acre Air National Guard base that remains active. The site was added to the EPA's National Priorities List in 1995 after aircraft operations and maintenance left behind contamination in soil, sediment, and groundwater.
Contaminants include per- and polyfluoroalkyl substances (PFAS), chlorinated solvents such as trichloroethene and tetrachloroethene, metals including lead, chromium, and arsenic, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), pesticides, and dioxin compounds. Groundwater contamination is concentrated near the Fire Training Area and Privet Road. Soil and sediment contamination is found primarily at the Ninth Street Landfill and South Landfill.
Cleanup is governed by a 2005 Federal Facilities Agreement among the EPA, Pennsylvania Department of Environmental Protection, and the Navy. The site is divided into 13 operable units. The EPA has signed cleanup decisions for eight of them. Several units are complete, including the Fire Training Area Groundwater site, which finished in 2014, and both the Antenna Field Landfill and Ninth Street Landfill, which finished in September 2023. Four units require no action or no further action. The PFAS operable unit for the Navy side (OU 12) is still active, with a cleanup decision and design estimated between September and November 2028. The Air National Guard PFAS unit (OU 22) began its combined investigation and feasibility study in June 2023, with completion estimated between June and August 2027. Human exposure at the site is currently under control, but contaminated groundwater migration has not yet been stabilized and physical construction is not complete across all units. The most recent five-year review was completed in September 2023, with the next review scheduled for 2028.
Community members can stay involved through the Restoration Advisory Board, which holds public meetings roughly three times a year in a hybrid format. The EPA's Technical Assistance Services for Communities Program held a community meeting on March 26, 2026, to review a Technical Assistance Needs Assessment. For updates on meetings, cleanup documents, and progress reports, community members can subscribe to the Navy's website. Documents can also be reviewed at the Horsham Township Public Library at 435 Babylon Road in Horsham, Pennsylvania, or at the EPA Region III office in Philadelphia, with an appointment recommended before visiting.
