Koppers Coke

Overview

The Koppers Coke site covers 38 acres in Saint Paul, Minnesota, where a foundry coke and by-products plant operated from 1917 to 1979. EPA added the site to the National Priorities List in September 1983 after an initial assessment found widespread contamination. The site is divided into two operable units, with the main cleanup unit addressing groundwater and soil across the property.

Coke production, storage practices, leaks, and spills left soil and groundwater contaminated with volatile organic compounds, semi-volatile organic compounds, polycyclic aromatic hydrocarbons (PAHs), metals, and cyanide. Groundwater testing found 33 contaminants of concern, including metals such as cadmium, lead, and mercury, organic chemicals like toluene and xylene, PAHs including naphthalene and pyrene, and cyanide.

The Minnesota Pollution Control Agency (MPCA) oversaw cleanup work carried out between 1981 and 1998. Workers demolished buildings, removed storage tanks, and excavated contaminated soil. The selected remedy for the deferral operable unit included air sparging and bioremediation to treat contamination in place, along with surface water discharge monitoring. A 2014 MPCA evaluation found that vapor intrusion from remaining groundwater contamination did not pose a risk. The most recent review confirmed that cleanup actions are working as intended.

Land cleanup is complete and human exposure is under control across the entire site. Groundwater remains lightly contaminated, and the MPCA continues to monitor natural improvement. Contaminated groundwater migration is stabilized with no unacceptable discharge to surface water. The site has not yet been deleted from the National Priorities List. Institutional controls, including zoning restrictions, remain in place to prevent incompatible uses such as residential development. The Saint Paul Port Authority redeveloped the broader area into Energy Park, a 218-acre industrial park that now includes office space, manufacturers, residential housing, and entertainment venues. As of December 2024, 12 on-site businesses employed 369 people and generated an estimated $264 million in annual sales revenue.

Community members who want to review site records can visit the Minnesota Pollution Control Agency at 520 Lafayette Road North, St. Paul, Minnesota. For questions, they can contact the EPA Remedial Project Manager or Community Involvement Coordinator. Questions can also be directed to the MPCA.