Lenz Oil Service, Inc. is a 4-acre former oil and solvent recycling facility in Lemont, Illinois. It operated from 1961 to 1985, accepting waste oil and solvents from commercial and industrial businesses. The site was added to the National Priorities List (NPL) in 1989, which is the federal government's roster of contaminated sites that need investigation and cleanup.
The facility contaminated soil, groundwater, and a floating layer of oil sitting on top of the aquifer below the site. Contaminants of concern include volatile organic compounds (VOCs) such as benzene, trichloroethene, tetrachloroethene, and vinyl chloride. The site also contains polychlorinated biphenyls (PCBs, specifically Aroclor 1242 and 1260), carcinogenic polycyclic aromatic hydrocarbons (PAHs), heavy metals, chloroform, and pesticides. These contaminants were found in soil, groundwater, and free-phase non-aqueous phase liquid (NAPL), which refers to oily contaminants that do not readily dissolve in water.
The U.S. Environmental Protection Agency (EPA) selected a cleanup remedy in 1999 and updated it in 2007. The remedy uses a containment wall around the contaminated area, a system to collect and treat groundwater and contamination, vapor extraction, air injection, and ongoing monitoring. Some contaminated waste was incinerated offsite, and soil was treated in place. In 2007, the EPA shifted some focus to extraction through vertical wells and discharge to a publicly owned treatment works (POTW). Land use restrictions prohibit residential development and the use of contaminated groundwater. Construction of the cleanup system was completed in September 2009.
Human exposure is currently under control. Contaminated groundwater migration has been stabilized, and there is no unacceptable discharge to nearby surface water. The site achieved a status of "sitewide ready for anticipated reuse" in September 2014, meaning all cleanup goals for current and future land uses have been met and required controls are in place. The EPA completed five-year reviews in 2014, 2019, and most recently in April 2024 to confirm the cleanup continues to protect people and the environment. A formal update to the remedy decision is planned between September and November 2027. The site has not yet been removed from the NPL.
Community members who want to learn more or ask questions can contact the EPA's Community Involvement Coordinator or the site's Remedial Project Manager directly. Public records including 9 key documents and 181 administrative records are available through the EPA's Superfund records system.
