Hill Air Force Base

Hill Air Force Base sits in northern Utah, roughly 30 miles north of Salt Lake City between the cities of Ogden and Layton. The installation opened as Hill Field in November 1940, built around the Ogden Air Depot, and became a major aircraft maintenance and supply hub during World War II. Today it is home to the Air Force Materiel Command's Ogden Air Logistics Complex, which performs depot-level maintenance on aircraft, engines, missiles, software, and avionics.

Decades of aircraft repair and depot operations generated significant volumes of industrial waste. From the 1940s through the 1970s, solvents and other chemicals were disposed of in unlined chemical pits, landfills, and fire training areas on base. Contamination has since been identified in 19 operable units, and groundwater plumes originating on base have migrated into surrounding residential communities, raising concerns about potential exposure for service members, civilian workers, and nearby residents.

1. Trichloroethylene (TCE). TCE is a chlorinated solvent that was widely used at Hill as a degreaser for aircraft parts and was disposed of in unlined pits for decades. According to the EPA, TCE is common to each of the site's groundwater operable units, and two shallow plumes extend westward off base beneath the communities of Sunset, Clinton, and Roy, with contamination also documented beneath Layton, South Weber, Riverdale, and Clearfield. Long-term exposure to TCE has been associated with kidney cancer and other serious health conditions, and the Air Force has tested indoor air in homes above the plumes for vapor intrusion.
2. Industrial solvents and degreasers. Beyond TCE, EPA records document chlorinated and non-chlorinated solvents, fuels, hydrocarbons, acids, bases, and metals in soil and groundwater at the base's chemical pits, landfills, and fire training areas. Some of these substances have been linked in studies to potential health effects, depending on the level and duration of exposure.
3. PFAS. PFAS, often called forever chemicals because they resist breaking down in the environment, are under remedial investigation at Hill as part of the Department of Defense PFAS cleanup program. In 2019, multiple areas of the base were recommended for investigation, and groundwater sampling has found PFAS concentrations above the EPA's former lifetime health advisory levels. Certain PFAS compounds have been associated with several cancers and other health concerns in some studies.
4. AFFF. AFFF, a firefighting foam containing PFAS, was used at Hill for decades in fire training and emergency response involving fuel fires. Historical AFFF use is the primary source of the PFAS contamination now being investigated, and the Air Force is phasing the foam out of its firefighting operations.

Hill Air Force Base was placed on the EPA National Priorities List on July 22, 1987, and a 1991 Federal Facility Agreement coordinates cleanup among the Air Force, the EPA, and the Utah Department of Environmental Quality. Remedies in place include landfill caps, pump-and-treat systems, soil vapor extraction, and a permeable reactive barrier treating TCE in Roy. Cleanup plans have been finalized for 16 operable units, with newer units still in early investigation, and groundwater restoration is projected to take decades. The most recent five-year review, completed in 2023, found the work proceeding as planned, though some protectiveness determinations remain pending.

Veterans and civilian employees who served or worked at Hill Air Force Base, as well as longtime residents of the surrounding communities, may want to follow the ongoing investigations and cleanup updates. Anyone with health concerns possibly connected to time at the base may want to discuss their service history with a VA health care provider and to review eligibility for VA benefits and registries.