Lehillier/Mankato Site

Overview

This 1,000-acre site in Blue Earth County, Minnesota, was used for uncontrolled dumping until 1972. That dumping left volatile organic compounds (VOCs), specifically tetrachloroethene and trichloroethene, in the groundwater. Testing in the early 1980s confirmed that contamination had reached residential wells and one municipal well serving Mankato, a city of 30,000 people. A new municipal well was built about one-quarter mile north of the contamination area.

The U.S. Environmental Protection Agency (EPA) added the site to the National Priorities List (NPL) in 1983. The NPL is the federal list of contaminated sites that qualify for Superfund cleanup funding. EPA signed a cleanup plan in 1985. That plan called for pumping and treating contaminated groundwater using extraction wells, extending the LeHillier community water system to affected residents and businesses, and properly abandoning individual drinking water wells. An alternative water supply for LeHillier was completed by the end of 1984, and a sanitary sewer system was installed in 1987. Remedial construction ran from March 1988 through April 1992. An Explanation of Significant Differences, issued in August 2008, updated the remedy to focus on extraction wells and institutional controls.

EPA has determined that human exposure across the entire site is currently under control, meaning there are no unacceptable exposure pathways at this time. Contaminated groundwater migration is stabilized, and there is no unacceptable discharge to surface water. The site achieved sitewide ready for anticipated reuse status in August 2010, meaning all cleanup goals for current and expected future land uses have been met. Today, 12 on-site businesses employ 243 people and generate an estimated $49 million in annual sales, and the site includes a park.

The Minnesota Pollution Control Agency has conducted regular five-year reviews since 1996. The most recent review, completed in September 2021, found the remedy continues to protect human health and the environment. The next five-year review is expected to be completed between May and July 2026. The site has not yet been deleted from the NPL, and operation and maintenance activities continue.

Community members can take part in the ongoing five-year review process. EPA encourages residents to share any observations about site conditions or concerns directly with agency contacts. Ruth Muhtsun serves as the Community Involvement Coordinator, and Andrew Kleist is the Remedial Project Manager. Both can be reached by email or phone.