The Chopawamsic Formerly Used Defense Site (FUDS) consists of the former Chopawamsic Troop Training Site and is 11,011 acres. The FUDS is located west of US Interstate 95 in Prince William County, Virginia, approximately 35 miles south of Washington, DC. The FUDS is located mostly within Prince William Forest Park, and is bordered to the south by the US Marine Corps Reservation, Quantico, and to the north by State Route 234. The U.S. Army Corps of Engineers is performing a Remedial Investigation at the Chopawamsic FUDS to determine if hazardous conditions exist to human health or the environment as a result of previous site activities.

A Site Inspection (SI) report was completed in 2007 which identified specific areas of the FUDS that should be investigated as part of the future Remedial Investigation (RI). Three Munitions Response Sites (MRSs) were identified as requiring a Remedial Investigation. The three MRSs that are being investigated include a total of 5,191 acres. The majority of these MRSs, 4,775 acres, are located on the Prince William Forest Park. There are 277 acres of the MRSs that extend beyond the FUDS boundary and encroach on the adjacent Marine Corps Base (MCB) Quantico. These MRSs also encompass 139 acres of privately owned parcels, most of which are used as private residences. The RI field effort will include metal detection surveys in areas where there is potential past military munition activities, digging of select detected metallic objects to determine if they are military munitions, and soil sampling to determine if there were any past releases of contamination into the soil.