Edwards Air Force Base sits across roughly 301,000 acres in Kern, Los Angeles, and San Bernardino Counties in California. It is an active military installation focused on aircraft research and development. The base was added to the National Priorities List (NPL), the federal Superfund program's roster of priority cleanup sites, in August 1990. Cleanup work is organized into 19 operable units, each targeting a specific area or type of contamination. Remedial action began in September 2006, and construction is not yet complete.
Decades of fuel and solvent spills and poor disposal practices released a wide range of contaminants. Chlorinated solvents such as trichloroethene (TCE) and tetrachloroethene (PCE) appear in groundwater and soil gas across multiple areas, and free-phase TCE exists at the South Base. Dense nonaqueous phase liquids (DNAPLs), which are heavy liquid contaminants that sink through soil and groundwater, are present in fractured bedrock at the Air Force Research Laboratory. Heavy metals including arsenic, lead, and chromium are found in soil. Per- and polyfluoroalkyl substances (PFAS) are being investigated basewide. Perchlorate, polycyclic aromatic hydrocarbons, and fuel-related compounds such as benzene and naphthalene round out the list of contaminants of concern.
The U.S. Air Force, as owner and operator, leads cleanup efforts. The EPA serves as the primary regulatory oversight agency under the federal Superfund law known as CERCLA (Comprehensive Environmental Response, Compensation, and Liability Act). The California Department of Toxic Substances Control and the Lahontan Regional Water Quality Control Board are also involved under a Federal Facilities Agreement signed in 1990. Cleanup actions completed to date include removing contaminated drums, tanks, and soils. Several units, including South AFRL Groundwater, NASA Dryden/Armstrong, AFRL Soil and Debris, and Chemical Weapons Materiel, have finished remedial construction and moved into long-term operation and maintenance. Active groundwater and soil vapor extraction systems operate at other units. Institutional controls limit certain areas to industrial use only.
As of the most recent five-year review completed in September 2022, human exposure is under control and groundwater migration is under control. Construction cleanup is not yet complete, and the site is not sitewide ready for anticipated use. Indoor air in some buildings is being investigated for vapor intrusion risk to base workers. Drinking water wells serving the roughly 14,000 base employees are not contaminated and are regularly tested. Nearby communities such as Lancaster and Boron are not affected by contamination.
Community members can participate through the Restoration Advisory Board (RAB), which meets twice a year at rotating locations near the base. The board brings together community representatives, regulators, and base officials for two-way discussion about cleanup progress. Meetings are open to the public. Documents are available through the Air Force's online Administrative Record and at local libraries in Rosamond and Lancaster. Questions can be directed to EPA staff, state agency contacts, or the base's own environmental representative.
