Naval Air Station, Whidbey Island (Ault Field)

Overview

Naval Air Station Whidbey Island (Ault Field) sits at the northern edge of Puget Sound on Whidbey Island, Washington. Air station operations dating back to the 1940s generated hazardous wastes that contaminated soil, sediment, and groundwater across the base. The EPA placed the site on the National Priorities List in 1990, and the Navy, as the lead federal agency, is responsible for cleanup. The site is divided into seven operable units, each targeting specific geographic areas and contamination problems.

Over 140 chemical contaminants have been identified at the site. Chlorinated solvents, including trichloroethene, 1,1,1-trichloroethane, and vinyl chloride, appear in soil and groundwater across multiple areas. Heavy metals such as lead, arsenic, cadmium, chromium, mercury, and zinc are found in soil, groundwater, sediment, and surface water. Polycyclic aromatic hydrocarbons, pesticides, petroleum hydrocarbons, and dioxins are also present. Groundwater is the most frequently affected medium, followed by soil, sediment, and surface water.

Construction of the initial cleanup finished in 1997 and covered landfill capping, soil and sediment excavation, groundwater extraction and treatment, bioventing, oil skimming, and land use controls. Later decision documents added monitored natural attenuation and chemical oxidation to the remedy for some areas. Despite completed construction, the site is not under control for human exposure, and groundwater migration has not been stabilized. Cleanup goals have not been fully met for current and expected future land uses, though redevelopment may still be possible on portions of the site.

Active work continues across several operable units. Removal work at Operable Unit 01 is estimated to finish between June and August 2026. Remedial investigation work at Operable Unit 02 is expected to conclude between December 2025 and February 2026. Operable Unit 05 has milestones running through early 2028. Operable Unit 06, covering OLF Coupeville, is undergoing a combined remedial investigation and feasibility study estimated to wrap up between September and November 2027. A sitewide study on per- and polyfluoroalkyl substances (PFAS) is planned, with a record of decision estimated for September through November 2028. PFOS (perfluorooctane sulfonic acid) and PFOA (perfluorooctanoic acid) have been detected in groundwater at several operable units. Off-site drinking water exposures have been addressed, and land use controls limit on-site groundwater exposure. The most recent five-year review, completed in September 2024, found that current actions are protective of human health and the environment in the short term.

Community members with questions can contact the EPA Remedial Project Manager and Community Involvement Coordinator. Site records are available at the Engineering Field Activity Northwest office in Poulsbo, Washington, and selected documents are held at the Oak Harbor Public Library.