Woodstock Municipal Landfill covers 40 to 50 acres in Woodstock, McHenry County, Illinois. The site was an open dump prior to 1969, when the city started burying municipal/industrial wastes in trenches. The city estimates that approximately 7,200 cubic yards of nickel sludge generated by the Autolite Plant in Woodstock were disposed at the landfill during 1972-76. The landfill ceased accepting waste after 1976 and in 1980 was placed on the "closed and covered" list of the Illinois Environmental Protection Agency.

During a March 1985 inspection, EPA observed leachate seeping at the site. Soil near the seepage contained cadmium, chromium, copper, lead, arsenic, and nickel.  Off-site groundwater was contaminated with vinyl chloride, a volatile organic compound (VOC).  On-site leachate contained VOCs and semi-VOCs  that include benzene, chlorobenzene, toluene, and naphthalene.  Metals were also detected in the leachate, including cadmium, arsenic, mercury, and cobalt.  Leachate was migrating from the site and contaminating area groundwater, surface water, and the nearby wetlands. Approximately 30 acres of freshwater wetlands adjacent to the Site and 1000 feet of the Kishwaukee River downstream from the Site were impacted. Surface water was contaminated with heavy metals. The site was proposed to be placed on the National Priorities List in June 1988 and was placed on the list in October 1989.