The A.I.W. Frank/Mid-County Mustang site covers 16 acres in Exton, Pennsylvania. It includes a former Styrofoam and refrigeration manufacturing property and a long-running auto repair operation. Improper disposal of solvents and degreasers contaminated soil and groundwater at both locations. EPA added the site to the National Priorities List in 1989. Cleanup has been organized into four operable units covering groundwater, a waterline, and soil.
Sixteen contaminants of concern have been identified in soil and groundwater. These include trichloroethylene, tetrachloroethene, various dichloroethanes, vinyl chloride, toluene, and 1,4-dioxane. All are located within the pump and treat operable unit and pose an unacceptable risk to human health or the environment.
Early cleanup steps included sealing floor drains, excavating contaminated soil, and connecting nearby homes to public water supply around 2000. A pump and treat groundwater system ran from roughly 1999 to 2008. A 2017 cleanup plan amendment added 1,4-dioxane as a contaminant of concern and shifted to in situ chemical oxidation (ISCO) and in situ bioremediation (ISBR), which inject chemicals and bacteria directly into the groundwater to break down contaminants. EPA completed an initial round of ISCO injections in August 2019, and testing through 2021 confirmed reduced 1,4-dioxane levels. In October 2025, EPA signed an Explanation of Significant Differences, confirming the ISCO and ISBR systems remain in place while the older groundwater extraction and treatment system has been removed. The Pennsylvania Department of Environmental Protection now handles operation and maintenance. The most recent five-year review, completed in 2026, found the cleanup protective of human health in the short term. EPA recommends continued PFAS groundwater monitoring to maintain long-term protection. The next five-year review is scheduled for 2031.
New homes in the Lochiel Farm development, built on the former A.I.W. Frank property, include vapor-mitigation systems to prevent resident exposure. Institutional controls prohibit new residential wells in the contaminated plume area and restrict groundwater use on nearby properties. An auto garage continues to operate on the Mid-County Mustang property.
Residents can stay involved through EPA's Community Involvement Program. In February 2026, EPA held a public availability session for nearby communities at their request. Site documents are available online through EPA's Administrative Record or in person at the West Whiteland Township Building at 222 North Pottstown Pike in Exton, or at EPA Region 3 in Philadelphia by appointment.
