EPA Superfund Site

HILL AIR FORCE BASE

UT | EPA ID UT0571724350

About this site’s exposure pathways: As of September 2025, the Hill Air Force Base Superfund site is considered Current Human Exposure Not Under Control (HENC). This is due to Vapor Intrusion (VI) off Base which is being addressed under Operable Unit (OU) 15, and PFAS in groundwater at OU19.
The Remedial Action Objective of OU15 is to prevent human exposure by inhalation to indoor air concentrations that are present due to VI above the contaminants respective risk-based action levels. Action levels are based on a cancer risk of 1 in 100,000 or a Hazard Quotient of 1. The VI exposure pathway is considered unacceptable based on EPA risk-based criteria. Some of the major contaminants of concern are trichloroethylene, perchloroethylene, vinyl chloride, and 1,2-dichloroethane. OU15 is unique in that there is only one contaminated medium (indoor air) and one exposure pathway (inhalation). The vapor sources are being remediated as part of the other OUs for soil and/or groundwater contamination. Therefore, the remedy for OU15 focuses on preventing exposure and not treating the vapor sources.
Although data is preliminary, perfluoroalkyl and polyfluoroalkyl substances (PFAS) have been found on-Base and may also contribute to a human health exposure as it migrates off-Base in groundwater. Whether there are volatile components of PFAS which may contribute to vapor intrusion is currently unknown. Remedial investigation work has begun, but it will take time to address the various sources and migration pathways. The Air Force is working on access agreements for off-Base investigation. The EPA estimates that human exposure will be under control in March 2034.