Letterkenny Army Depot SE Area sits on an active U.S. Army installation in Chambersburg, Pennsylvania. The Army used the site to overhaul vehicles, maintain military ordnance, and operate warehouses. Those operations left behind solvents, paints, petroleum products, and metals that contaminated soil, groundwater, surface water, sediment, and soil gas. The site was added to EPA's National Priorities List in 1987.
Contaminants of concern include chlorinated solvents such as trichloroethene, tetrachloroethene, and vinyl chloride, metals including lead, chromium, arsenic, and cadmium, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and explosives-related compounds like RDX and HMX. The Army is also investigating per- and polyfluoroalkyl substances, specifically PFOA and PFOS, linked to aqueous film forming foam used in firefighting. Trichloroethene appears in multiple locations across groundwater, soil gas, and surface water.
The U.S. Army leads cleanup under a 1989 Federal Facilities Agreement with EPA and Pennsylvania. The site is divided into 37 operable units. Cleanup methods include excavation, engineered caps, in-situ chemical oxidation, monitored natural attenuation, vapor intrusion mitigation, and institutional controls. Several units have completed remedial actions. Two remain active: OU 36, focused on the SE OU 17 SAFR area, with cleanup estimated for 2028, and OU 37, a sitewide PFAS investigation that began in April 2017. The most recent five-year review was completed in March 2022.
Human exposure is under control across the site. However, contaminated groundwater migration has not been stabilized. Physical construction of the cleanup is not complete, and the site is not yet ready for anticipated use sitewide. Land use controls, including deed restrictions, groundwater use prohibitions, vegetative caps, and fencing, are in place to limit exposure. Because the site is an active military installation, most operable units are not accessible to the public.
Community members can follow cleanup progress through announcements in the Chambersburg Public Opinion and Shippensburg News-Chronicle newspapers. The Letterkenny Army Depot Public Affairs Office can be reached at 717-267-5482 or usarmy.letterkenny.usamc.public-affairs-office@army.mil. The Community Involvement Plan, last updated in April 2020, supports resident participation in cleanup decisions. Documents are available for review at 1 Overcash Avenue in Chambersburg, or by contacting the Public Affairs Office.
