The Oconomowoc Electroplating Co., Inc. site sits in the unincorporated town of Ashippun, about 35 miles west of Milwaukee. The facility ran from 1957 to the early 1980s. During that time, untreated wastewater was discharged into nearby wetlands and Davy Creek, and two unlined lagoons holding electroplating sludge leaked and overflowed. Those releases contaminated groundwater with volatile organic compounds, or VOCs.
Cleanup was organized around five areas covering surface water, sludge, contaminated soils, groundwater, creek sediments, and facility demolition. A pump and treat system ran from 1996 to 2004 to address groundwater, but it was shut down after losing effectiveness. In 2011, the cleanup plan was updated to rely on natural attenuation, meaning natural processes in the ground break down contaminants over time. Then in 2013, a method called in situ soil mixing treated more than 2,200 cubic yards of contaminated material directly in the source areas without excavating it.
The Wisconsin Department of Natural Resources oversees ongoing site maintenance and groundwater monitoring. The U.S. Environmental Protection Agency, or EPA, monitors the natural attenuation process. An EPA five-year review completed in 2023 found that the current remedy protects human health and the environment. To maintain that protection over the long term, an Institutional Controls Implementation and Assurance Plan and formal institutional controls still need to be put in place.
Community members who want to stay informed can track site updates through the EPA's Superfund site records, which include five-year review reports and remedy decision documents. Reaching out to the EPA or the Wisconsin Department of Natural Resources directly is another way to get current information on monitoring results and next steps.
