The Matthiessen and Hegeler Zinc Company ran a zinc smelter and rolling mill in La Salle, Illinois from 1858 until operations ended in the area around 2001. The U.S. Environmental Protection Agency (EPA) placed the site on the National Priorities List (NPL), a roster of the country's most contaminated sites, in September 2003. The site covers roughly 160 acres and includes a slag pile along the Little Vermilion River and a contaminated residential area in neighboring Peru, Illinois.
Contaminants found in soil include metals such as lead, cadmium, arsenic, chromium, copper, nickel, and zinc, along with polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), asbestos, cyanide, and trichloroethene. Groundwater contains metals, semi-volatile organic compounds, and volatile organic compounds. River sediment also shows elevated levels of cadmium, copper, chromium, lead, nickel, and zinc. In 1999, the Agency for Toxic Substances and Disease Registry (ATSDR) and the Illinois Department of Public Health declared the site a public health hazard because of cadmium and lead in soil in the adjacent residential area. Human exposure is not currently under control at the site. Groundwater migration, however, is under control, with contaminated groundwater stabilized and no unacceptable discharge to surface water.
EPA selected a cleanup plan in April 2017. It calls for placing soil covers over contaminated industrial areas and the slag pile, excavating and replacing contaminated residential soil, and managing surface water runoff. EPA updated the plan in August 2019 to set separate cleanup levels for garden areas and non-garden residential areas. A further amendment in September 2023 added engineered caps and modified remedy elements across two operable units (OUs), which are distinct cleanup areas. EPA also conducted emergency removal actions in 2003 to 2004 and 2008 to address cyanide, asbestos, and other hazardous materials, and began removing lead-contaminated soil from residential properties in 2018. Potentially responsible parties removed contaminated waste piles, asbestos, and storage tanks, and EPA demolished a contaminated building in 2009. The Carus Chemical Company continues manufacturing on part of the site and is conducting additional studies on its portion. EPA is also updating the residential lead cleanup level to comply with a federal directive from October 2025, with a formal document expected in Fall 2026.
Physical construction is not yet complete across the entire site, and the site has not been removed from the NPL. The most recent five-year review was completed in September 2024. Institutional controls, including zoning restrictions and groundwater access prohibitions, are in place to limit exposure in the meantime.
Community members can attend an EPA open house on Wednesday, May 20th at 4 pm at the LaSalle Public Library Meeting Room, 305 Marquette Street, La Salle, Illinois 61301. The library also serves as a public information repository where site records can be reviewed. EPA offers two citizen guides on cleanup methods used at the site: A Citizen's Guide to Capping and A Citizen's Guide to Excavation of Contaminated Soil. Questions can be directed to the EPA staff assigned to the site.
