Middletown Air Field covers 200 acres in Dauphin County, Pennsylvania. The U.S. Air Force operated it from 1868 to 1966, and the Harrisburg International Airport took it over afterward. Aircraft maintenance and testing left the soil, groundwater, and surface water contaminated with hazardous chemicals. EPA added the site to the Superfund National Priorities List in June 1986. It was deleted from that list in July 1997 after cleanup goals were met.
The main contaminants are volatile organic compounds (VOCs), including trichloroethylene (TCE), tetrachloroethene, benzene, and several chlorinated hydrocarbons. Metals such as lead, chromium, cadmium, arsenic, barium, nickel, and zinc were also found. EPA identified 36 contaminants of concern across groundwater, soil, and surface water. In 2014, perfluorooctane sulfonic acid (PFOS) was detected in groundwater above EPA's health-based screening level, likely from Harrisburg International Airport operations, and is being handled through drinking water programs.
Cleanup was organized into three operable units. The public water supply unit ran remedial action from 1988 to 1990. The groundwater and surface water unit was active from 1994 to 1996. The supplemental soil study unit required no further action beyond monitoring and institutional controls. A groundwater treatment system has operated since 1987. In October 2023, EPA approved an upgrade from an air stripper to a Granular Activated Carbon (GAC) treatment system. This upgrade addresses both site-related contaminants and non-site-related contaminants to drinking water standards. The current site owner and operator is funding the upgrade. Institutional controls limit residential development, restrict groundwater use, and require soil sampling during any excavation work.
The most recent five-year review, completed in July 2022, confirmed the remedy is still protective of human health and the environment. Human exposure is under control, groundwater migration is stabilized, and physical construction is complete. The site is also confirmed ready for its anticipated future land uses. The next five-year review is scheduled for between July and September 2027. As of December 2024, 43 businesses operate on the site, employing 1,669 people and generating roughly $185 million in annual sales.
Community members can review site documents at the Middletown Public Library at 20 N. Catherine Street, Middletown, PA 17057, or at the U.S. EPA Region 3 Public Reading Room at 1600 John F. Kennedy Boulevard, Philadelphia, PA 19103 (by appointment). Questions can be directed to the site's Community Involvement Coordinator or Remedial Project Manager. The Agency for Toxic Substances and Disease Registry, the Pennsylvania Department of Environmental Protection, and the Pennsylvania Department of Health can also provide additional information.
