Naval Support Activity (NSA) Mechanicsburg is located in Hampden Township and the Borough of Mechanicsburg, Cumberland County, Pennsylvania. The activity occupies nearly 824 acres of land, of which the largest portion is designated as grounds for storage. The United States Environmental Protection Agency placed NSA Mechanicsburg on the National Priorities List in May 1994. The Installation Restoration Program began in 1984 and a total of 66 IRP sites were identified. Ongoing Land Use Controls are part of the remedies at Sites 1, 3, 8 and 9; groundwater monitoring is ongoing at Site 3, and periodic soil/sediment monitoring is part of the remedy for Site 9. The remediation of Site 3 groundwater is an ongoing remedial action.