EPA Superfund Site

AIR FORCE PLANT #4 (GENERAL DYNAMICS)

TX | EPA ID TX7572024605

About this site’s exposure pathways: As of September 2025, the Air Force Plant 4 Superfund Site is considered “Insufficient Data to make a Human Exposure evaluation” (HEID) because of a newly identified exposure pathway and/or contaminant(s) known as per-fluor-alkyl substances (PFAS) and the ongoing implementation of a long-term monitored natural attenuation (MNA) remedial action at the site. The site was previously categorized as Human Exposure Under Control (HEUC). Limited data is available based on a preliminary site investigation and review of PFAS releases at the site that were completed in 2019 and 2023. The 2019 and 2023 investigations found PFAS in groundwater in several groundwater monitoring wells are above the current maximum concentration levels (MCLs) and that various soils and sediments are above the regional screening levels. The concentrations in soil, ground water, and surface water need to be delineated and assessed for potential exposure risks.

EPA uses this HEID 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 this new potential exposure are to conduct a remedial investigation (RI), which will include a Human Health Risk Assessment (HHRA) and information about the human interactions with potentially contaminated media. The PFAS contaminants may be co-mingled with legacy contaminants in groundwater associated with other contaminant releases and could impact the currently selected remedies. One or more new operable units (OUs) may be established to facilitate response actions. Direct soil exposure and ingestion of ground water pathways must be evaluated. EPA anticipates a human exposure evaluation by 2027.