Highway 100 and County Road 3 Groundwater Plume

Overview

A large underground plume of chlorinated solvents spread across parts of Edina and St. Louis Park, a suburban Minneapolis area in Hennepin County, Minnesota. The contamination first came to light in 2004 when vinyl chloride turned up in an Edina municipal well. EPA added the site to its National Priorities List (NPL) in September 2020, making it an official Superfund site. The source of the contamination has not been identified.

The plume carries four main contaminants: tetrachloroethene (PCE), trichloroethene (TCE), cis-1,2-dichloroethylene (cis-DCE), and vinyl chloride. These are industrial solvents. Long-term exposure to them in drinking water poses health risks. Both Edina and St. Louis Park treat all municipal drinking water to remove these volatile organic compounds (VOCs), and the water currently meets EPA Maximum Contaminant Levels set by the Safe Drinking Water Act. Edina built a centralized water treatment facility for its affected wells. St. Louis Park completed a treatment system at one municipal supply well, which returned to service in 2018.

Vapor intrusion, where these chemicals move from groundwater up into indoor air, was also addressed. Since 2008, about 40 residential and commercial properties have had vapor mitigation systems installed. Despite these protective steps, EPA tracking shows insufficient data to confirm whether human exposure risks are fully controlled or whether contaminated groundwater movement has been stabilized. Physical cleanup construction is not complete, and the site is not yet ready for its anticipated future use.

EPA started a combined Remedial Investigation and Feasibility Study (RI/FS) on September 26, 2024. This study will map the full extent of contamination and evaluate cleanup options. EPA is also searching for potentially responsible parties, the companies or individuals who may have caused the contamination, and has issued information requests to determine who should fund or carry out cleanup work. A remedy has not yet been selected.

Community members in the affected area are forming a Community Advisory Group (CAG) to share concerns and stay informed. EPA held information sessions in May 2023 on how to set up the CAG. A Community Involvement Plan is available for review, and recordings from past meetings can be accessed online. The Minnesota Pollution Control Agency (MPCA) and the Minnesota Groundwater Contamination Atlas also offer resources about the site. Residents with questions can reach EPA's Community Involvement Coordinator Kirstin Safakas or Remedial Project Manager Andrew Kleist directly.