The Waste Disposal Engineering site is a former landfill in Andover, Minnesota that operated from 1968 to 1983. It accepted 2.4 million cubic yards of municipal, commercial, and industrial waste across 76 acres. From 1972 to 1974, waste with higher concentrations of hazardous materials was buried in a pit within the landfill. That pit contaminated the groundwater beneath the site. Area residents rely on groundwater for drinking water, though the landfill did not affect municipal water supply wells.
EPA identified ten contaminants of concern in groundwater and landfill gas. These include volatile organic compounds such as benzene, xylene, dichloromethane, and trichloroethane. Other contaminants are 1,1,2,2-tetrachloroethane, 1,2-dichloroethene, 1,3-dichloropropene, 2-butanone (also called methyl ethyl ketone), and tetrahydrofuran. All posed unacceptable risks to human health or the environment.
EPA added the site to the National Priorities List in September 1983. The final cleanup plan was selected in December 1987 and construction began in December 1992. Workers installed a groundwater pump-and-treat system, a clay barrier around the hazardous waste pit, landfill gas collection, and an improved cap. Construction was completed in August 1995, and EPA removed the site from the list in June 1996. The Minnesota Pollution Control Agency (MPCA) later removed the hazardous waste pit and contaminated soils in 2019 and continues operating the cap, gas collection, and groundwater treatment systems under its Closed Landfill Program. EPA's 2023 five-year review found the remedy is working as intended and protecting public health in the short term. The next five-year review is estimated for April through June 2028.
In 2021, private wells south of the landfill were found to contain 1,4-dioxane and PFAS (per- and polyfluoroalkyl substances). MPCA provided bottled water to residents in the Red Oaks and Eastbrook Terrace neighborhoods where 1,4-dioxane exceeded Minnesota's Health Risk Level of 1 microgram per liter. The source of this contamination has not been determined. Potential sources include the WDE landfill and the nearby South Andover Superfund site. Investigations are ongoing. Human exposure is currently under control at the site, though groundwater migration status remains uncertain due to insufficient data, and EPA will continue monitoring.
Community members with questions can contact the EPA's Community Involvement Coordinator, Ruth Muhtsun, by email or phone. The Remedial Project Manager, Leslie Patterson, handles technical cleanup matters. For questions about the closed landfill under state oversight, John Hunter at the MPCA is the Land Manager. Site records are available for public review at the MPCA office at 520 Lafayette Road N, St. Paul, Minnesota 55155.
