This 183-acre site in Fridley, Minnesota operated as a wood-treating facility from 1921 to 1961 under the name National Pole Treating Co. The operations left creosote, phenols, and related chemicals in soil, sediments, soil vapor, and groundwater. EPA added the site to the National Priorities List (NPL) in September 1984. The Onan Corporation and Medtronic, Inc. later acquired portions of the property for commercial and manufacturing use.
Cleanup addressed two main parcels. At the Onan property, workers excavated contaminated soil, contained it on-site, and ran a groundwater extraction and treatment system. At the Medtronic property, workers excavated and hauled contaminated soil off-site, treated groundwater, and disposed of about 5,000 gallons of oil. Construction finished in 1992, and EPA deleted the site from the NPL in February 1995. Additional contamination turned up during later redevelopment work. In 1999, drums and soil were removed. In 2009, more soil was removed, and a slab-on-grade building with a vapor barrier and venting system was constructed to protect occupants from vapor intrusion.
EPA has identified 26 contaminants of concern at the Medtronic portion of the site, all found in groundwater. These include polycyclic aromatic hydrocarbons (PAHs) such as naphthalene, benzo[a]pyrene, anthracene, pyrene, and fluoranthene, along with other organic compounds like quinoline, dibenzofuran, and carbazole. One PAH was also detected in surface water. Human exposure across the site is currently under control, meaning no unacceptable exposure pathways exist. Contaminated groundwater migration has been stabilized, and monitoring continues to confirm it stays contained.
The site is in active reuse today. Medtronic built an office building and parking lot on the western portion, and Cummins (formerly Onan Corporation) runs office and manufacturing facilities on the eastern side. As of December 2024, three on-site businesses employ 3,304 people and generate about $1.2 billion in annual sales. Institutional controls, including zoning restrictions, are in place to prevent residential development or other incompatible land uses. Physical cleanup construction is complete, but not all cleanup goals for anticipated future land uses have been fully achieved sitewide.
The Minnesota Pollution Control Agency (MPCA) conducts five-year reviews to confirm the remedy stays protective of human health and the environment. The most recent review, completed in September 2004, confirmed that response actions are working as intended. Long-term groundwater monitoring continues at both properties. Community members with questions can contact the EPA Remedial Project Manager.
