MIDCO II

Overview

MIDCO II is a 7-acre Superfund site in Gary, Lake County, Indiana. It operated as a chemical storage and disposal facility from January through August 1977, when a major fire destroyed or damaged an estimated 50,000 to 60,000 drums on site. The property is on the National Priorities List and has not yet been deleted from it. The Gary-Chicago International Airport has plans to reuse the property, and the site cover may be designed to support airport expansion.

Contamination affects both soil and groundwater. More than one hundred chemicals have been identified, including volatile organic compounds (VOCs) such as benzene, trichloroethene, tetrachloroethene, and vinyl chloride. Heavy metals including arsenic, lead, and chromium are present, along with pesticides like DDT, aldrin, and dieldrin, as well as polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs). A newer contaminant, 1,4-dioxane, was recently detected using improved lab methods, reaching 880 micrograms per liter in on-site groundwater and 630 micrograms per liter in off-site groundwater as of 2010. Contaminated sediments pose a risk to wildlife and plants in nearby wetlands, though those sediments are not currently moving off site.

Cleanup has gone through several phases. EPA fenced the site in 1981 and removed wastes and contaminated soil from 1984 to 1989. A groundwater extraction and treatment system ran from 1992 to 1996. A soil vapor extraction system operated from 2006 to 2013 and cut VOC levels by over 97%. In-place chemical treatment followed in 2014, and a final soil and sediment cap was completed in 2016. In 2022, the groundwater remedy shifted from pump-and-treat to monitored natural attenuation (MNA), which relies on natural processes like dilution and microbial breakdown to reduce contamination. Cleanup construction was completed on September 4, 2020, and the site reached sitewide ready for anticipated reuse status on September 30, 2020.

The most recent five-year review, completed January 8, 2025, found the site to be short-term protective of human health and the environment. Human exposure is considered under control through fencing, on-site staff, deed notices, and restrictions on groundwater and residential use. However, data on groundwater migration remains insufficient to confirm whether contamination movement is stabilized. Actions still needed for long-term protection include sampling for PFAS compounds, a field investigation into the full extent of 1,4-dioxane contamination, and a climate vulnerability assessment.

Community members with questions can contact the EPA's Community Involvement Coordinator or Remedial Project Manager. EPA is working alongside the Indiana Department of Environmental Management (IDEM) on ongoing oversight of the site.