The Kerr-McGee Sewage Treatment Plant site covers about 25 acres in West Chicago, Illinois, plus roughly 1.2 miles of the West Branch of the DuPage River. Radioactive waste from a nearby Rare Earths Facility, which operated from 1932 to 1973, was hauled to the treatment plant starting in the 1960s. That facility produced rare earth elements and radioactive materials, including thorium, radium, and uranium, for private customers and federal atomic energy programs. EPA added the site to the National Priorities List in 1990 after a voluntary cleanup in 1986 and 1987 revealed additional contamination.
The main contaminants are radioactive: Radium-226, Radium-228, Thorium-232, Uranium-235, and Uranium-238. All were found in both upland soil and river sediment. EPA determined they posed an unacceptable risk to human health and the environment based on the types and amounts present.
Cleanup happened in stages. Workers removed 6,557 cubic yards of contaminated soil from the 25-acre upland area in a time-critical removal action completed in December 2004, with final restoration finished in 2006. Contaminated soils and sediments along the river were removed in 2004 and 2005, and river restoration wrapped up in 2008. Federal actions and potentially responsible party actions both contributed to the cleanup. A Trust created from Tronox's 2009 bankruptcy settlement, Tronox being the successor to Kerr-McGee, completed remaining cleanup and monitoring requirements. The Forest Preserve District of DuPage County, which owns most of the river land, partnered with EPA on restoration goals and helped fund the work.
The site has been cleaned to an unrestricted use standard for thorium. Human exposure is under control, and groundwater migration is stabilized with no unacceptable discharge to surface water. Institutional controls, including zoning restrictions, remain in place to prevent residential development and other uses that would not match the cleanup level. As of December 2024, one on-site business employed 3 people, and the river is used primarily for recreation. EPA deleted the site from the National Priorities List in April 2013 after confirming all maintenance and monitoring requirements had been met.
Community members with questions can contact the EPA's Community Involvement Coordinator or Remedial Project Manager.
