The facility, which operated from 1931 until its closure in 1973, extracted radioactive thorium and other radioactive and non- radioactive elements from monazite and other ores, and manufactured gaslight mantles, mesothorium, and hydrofluoric acid. The site became contaminated when the waste materials from these operations, known as thorium mill tailings, were used as fill in and around the park or disposed in an area previously operated as an open city dump between 1939 and 1974. Approximately 15,000 people live within 3 miles of the site. This site is being addressed through Federal and potentially responsible parties' actions. Threats and Contaminants Elevated concentrations of radioactive wastes have been detected in air samples.
Soil contains heavy metals and radioactive wastes.
People who come into direct contact with or accidentally ingest contaminated soil or inhale contaminated air may be at risk. Based upon review of the data, U.S. EPA determined that significant risks existed at the site resulting from the presence of radioactive contaminated waste at the surface and decided to implement a time-critical removal action to expedite the cleanup. Kerr-McGee began excavation work at the site in April, 1997. Based upon a negotiated agreement with the City of West Chicago, Kerr-McGee has excavated contaminated materials below the water table and verified based upon required elevations. As of November 2000, Kerr-McGee has completed the excavation of contaminated materials at the site.