Hanscom Field and Hanscom Air Force Base sit across about 1,120 acres in Bedford, Concord, Lexington, and Lincoln in eastern Massachusetts. The Air Force owns roughly 396 of those acres and operates the Electronic Systems Center there. The site was added to the National Priorities List in 1994 after the Air Force identified 22 possible contamination sources, including fire training areas, waste disposal sites, landfills, petroleum releases, and spill sites. The Massachusetts Port Authority now operates the civilian airport portion known as L.G. Hanscom Field.
Contaminants in groundwater and soil include chlorinated solvents such as trichloroethene, tetrachloroethene, 1,1,1-trichloroethane, and 1,2-dichloroethane, along with benzene, toluene, acetone, and vinyl chloride. Other areas contain polycyclic aromatic hydrocarbons, pesticides including DDT compounds, metals such as arsenic, lead, cadmium, and mercury, and petroleum-related compounds. Per- and polyfluoroalkyl substances, known as PFAS, and 1,4-dioxane are also under active investigation. Contamination affects groundwater, soil, sediment, and surface water. Potable water for the base comes from municipal suppliers in Lexington and Concord, so the contaminated groundwater is not used for drinking.
The Air Force is the lead agency for cleanup, with the EPA overseeing compliance under CERCLA, the Comprehensive Environmental Response, Compensation, and Liability Act. The Air Force and EPA signed a Federal Facility Agreement in 2009. Cleanup actions have included removing drums and contaminated soil, installing boundary interceptor wells, capping a former municipal landfill, and running groundwater extraction and treatment systems. Major construction was completed by September 2007, and the site was declared ready for anticipated reuse in 2008. Most areas are now in the operation and maintenance phase, with long-term groundwater and surface water monitoring ongoing. The dynamic groundwater remediation system was suspended after PFAS was detected in discharge to the Shawsheen River, and a plume stability study is underway. A combined remedial investigation and feasibility study for the Base Landfill area has been ongoing since January 2023, with a projected conclusion between late 2027 and early 2028.
EPA completed a five-year review in September 2022 and found that cleanup actions are protective of human health. The agency determined that human exposure is under control and that contaminated groundwater is stabilized. Institutional controls restrict land use to recreation, prohibit residential use, and prevent drinking water use from the site. These controls remain in place as long as contamination or cleanup components are present.
Community members can contact the EPA's Community Involvement Coordinator. Public information repositories were established at local town libraries, and the EPA Remedial Project Manager can direct residents to additional records.
