Hill Air Force Base officials update Layton City on PFAS groundwater investigation

Jared Case, project manager for the Hill Air Force Base cleanup program, told the Layton City Council on May 15 that the Air Force is expanding its investigation into per- and polyfluoroalkyl substances (PFAS) found in shallow groundwater near the base.

Case said the Air Force has identified multiple areas of firefighting-foam use and other potential sources and is in the remedial-investigation phase to determine “the nature and extent” of contamination. He noted the EPA finalized a drinking-water rule in April 2024 that sets maximum contaminant levels for several PFAS chemicals and that the Defense Department is using those levels to guide sampling and response work.

The presentation outlined the scope of sampling and mapping completed to date, and the distinction between “legacy” contaminants such as chlorinated solvents and the PFAS detections. Case said the Air Force has installed extraction wells and interim treatment where warranted and that no residents in the city are currently relying on the affected shallow groundwater as a public drinking source. “There are no people drinking water with PFOA or PFOS from the Air Force, Hill or Hickam Hill,” Case said.

Why this matters: PFAS are persistent in the environment and often appear at very low concentrations measured in parts per trillion. Case told the council the recently adopted EPA rule establishes MCL-style benchmarks for a handful of PFAS chemicals; the Air Force and other water suppliers will have up to five years to implement treatment where required under the Safe Drinking Water Act framework. Because PFAS can move differently in groundwater than other contaminants, the investigation is adding monitoring wells and refining plume boundaries.

Details from the briefing: Case described the Air Force’s phased CERCLA (Comprehensive Environmental Response, Compensation, and Liability Act) process: preliminary assessment, site inspection and the ongoing remedial investigation to map the plume and identify risks. He said the team is also assessing background PFAS levels from other sources (for example, airports, landfills and consumer products) to distinguish base-related releases. Case said the Air Force prioritizes “interim actions” when sampling shows an immediate risk — for example, providing point-of-entry treatment or alternate water supplies to affected private wells — rather than waiting for the final remedy decision.

Council members asked about plume extent, monitoring and treatment. Case pointed to a detailed map he offered to share with city staff and the local Restoration Advisory Board and said the current dashed boundary reflects ongoing work to define the plume. He described steps already in place to limit migration, including extraction wells and base-boundary controls.

What happens next: Case said the Air Force will continue sampling and expanding monitoring wells to refine the extent of contamination, complete a baseline risk assessment, and follow the CERCLA process toward a record of decision while using interim measures where risk is identified. The Air Force will provide annual mapping data and continue coordination with U.S. EPA, the state and local stakeholders.

Ending: City staff thanked the Air Force team for the update and for sharing map files and the Restoration Advisory Board meeting schedule. Residents with technical questions or who want the map data were directed to the Air Force public-affairs contacts Case provided.