The Eau Claire Municipal Well Field supplies drinking water to tens of thousands of residents and commercial users in Eau Claire, Wisconsin through 14 groundwater wells split across two well fields. The site was added to the National Priorities List in 1984 after routine state sampling found volatile organic compounds in the municipal water supply. EPA traced the contamination to the nearby National Presto Industries Superfund site.
The contaminants found in groundwater include trichloroethene, tetrachloroethene (also called perchloroethylene), 1,1,1-trichloroethane, dichloroethane, dichloroethene, chloroform, and mixtures of dichloroethene isomers. These volatile organic compounds posed unacceptable risks through ingestion, inhalation, and skin contact with affected water. The nearby Chippewa River was not affected, because pumping the municipal wells prevented contaminated groundwater from reaching the river.
EPA installed an air stripper in 1987 to remove contaminants from the groundwater. Other actions included connecting private wells to the municipal system, installing extraction wells, and temporarily replacing water supplies for affected residents. The first cleanup decision came in June 1985 and called for air stripping with discharge to the local wastewater treatment facility. A second decision in March 1988 added surface water discharge under a National Pollutant Discharge Elimination System permit, recovery wells, and water supply monitoring. Two follow-up documents issued in 2008 and 2009 added extra treatment methods and updated cleanup standards to match Wisconsin's state enforcement rules under Administrative Code NR 140.
Testing confirmed that groundwater entering the well field met cleanup standards for more than five consecutive years. The air stripper was shut down in November 2011, and confirmation sampling showed the drinking water continued to meet cleanup goals without it running. EPA deleted the site from the National Priorities List on May 27, 2014. Five-year reviews were completed in 1997, 2002, 2007, and 2012. The most recent review confirmed that cleanup actions continue to protect public health and the environment. Human exposure is considered under control and groundwater migration is stabilized. The site has not yet achieved sitewide ready-for-anticipated-reuse status, meaning some cleanup goals or controls still need to be met for current and future land uses.
Community members with questions can contact the EPA's Community Involvement Coordinator or Remedial Project Manager directly. Public records about the site are available at the L.E. Phillips Memorial Public Library at 400 Eau Claire Street in Eau Claire. EPA also maintains an administrative record of 175 documents covering the site's full history and cleanup actions.
