Brandywine Superfund Site
The United States Army Corps of Engineers (USACE), Omaha District, on behalf of the United States Air Force (USAF), selected HydroGeoLogic Inc. (HGL) and TRS Group, Inc. (TRS) to perform the final groundwater remedy at the Brandywine Superfund Site located on USAF Joint Base Andrews offsite property in Brandywine, Maryland. The remedy was completed under a performance-based contract and consisted of Electrical Resistance Heating (ERH) remediation of the groundwater plume source.
Initially, the Site was used by the United States Navy as a storage area from 1943 through 1961 (URS, 2006). From 1961 to 1987, the Site was operated the USAF as a storage area for waste and excess government material (IT Corporation, 1999) generated by the United States Department of Defense (DoD) operations at various facilities including Andrews Air Force Base (AFB), Bolling AFB, the Washington Navy Yard, the Naval Ordnance Station-Indian Head, and White Oak Laboratory (Dames & Moore, 1992). According to USAF records, hazardous materials and wastes, including spent solvents, were stored at the Site within drums and several concrete bins (Dames & Moore, 1991). Detailed information on where solvent drums were stored and how the wastes were handled at the Site is not available.
The contaminants of concern are chlorinated volatile organic compounds, primarily trichloroethylene (TCE) and 1,4-dichlorobenzene (DCB). Following 4 ½ years of groundwater pump and treat and three injection rounds of enhanced reductive dechlorination (ERD), the groundwater plume was reduced from 20 to 1.5 acres, over a 90% reduction in area. High resolution site characterization (HRSC) using membrane interface probe and passive flux meters identified the low permeability unit as the continuing source of contamination and rebound. The results of the HRSC indicated a limited residual source mass estimated at 300 pounds. The ERH remedial objective was to reduce TCE groundwater concentrations to a maximum of 5 micrograms per liter (µg/l) and to reduce DCB groundwater concentrations to 75 µg/l per liter.