From 1917 to 1972, an 80-acre plant in St. Louis Park, Minnesota distilled coal tar and treated wood. Those operations left soil, groundwater, and a nearby peat bog contaminated with polycyclic aromatic hydrocarbons (PAHs), including benzo[a]pyrene, creosote, and pentachlorophenol. Wastewater discharge forced the closure of six drinking water wells in St. Louis Park and one in Hopkins. The site was added to the National Priorities List (NPL) on September 8, 1983, which designates it as a priority for federal cleanup under the Superfund program.
Cleanup is organized into six operable units, each targeting a specific contamination problem or aquifer. The peat bog was filled and covered with clean soil in 1986. Drinking water treatment plants came online in 1985 and 1992, and groundwater pumping wells began operating in 1987 to stop contamination from spreading. Construction of the main cleanup work was completed on June 30, 1997. Contaminated soil remains in place, covered by clean fill. About 47,000 people now drink treated groundwater from aquifers near the site, and that water meets all required health standards. A 2020 amended consent decree requires the City of St. Louis Park to finance and carry out remaining groundwater cleanup work.
EPA completed a vapor intrusion investigation in 2013 and found no unacceptable risk from that pathway. Human exposure is currently under control, and contaminated groundwater has been stabilized in its original area. The sixth five-year review, completed in June 2021, confirmed the remedy protects human health and the environment because affected drinking water is treated before use. However, not all cleanup goals for future land uses have been met, and the site has not yet been deleted from the NPL. It is estimated to be ready for anticipated reuse between June and August 2027.
Parts of the site are already in active reuse for commercial, residential, and recreational purposes. Townhomes and apartments were built on-site in the 1970s, and a park improvement project was completed in 2002. As of December 2024, eleven on-site businesses employed 96 people and generated about $11.3 million in annual sales. Institutional controls and zoning restrictions remain in place to limit land uses that are not consistent with the current level of cleanup.
The City of St. Louis Park monitors 75 groundwater wells across five aquifers. EPA, the Minnesota Pollution Control Agency (MPCA), and the Minnesota Department of Health (MDH) provide oversight. Community members can find additional resources through the City of St. Louis Park's site portal and can reach EPA or state agency contacts directly for questions about the cleanup.
