Minneapolis | General Mills/Henkel Corp. contamination

The pollutant of concern in the groundwater contamination at General Mills/Henkel Corp. Superfund Site in Minneapolis is trichloroethylene (TCE).

Health and environmental concerns

TCE is a common industrial solvent and degreaser. In the past, chemicals were placed in an absorption pit located in the southeast corner of the property. Although, this was common practice at the time, the TCE disposal at the site created an area of groundwater contamination (known as a “plume”) that extends about 1/2 mile southwest. Even though the groundwater was treated and was never a health risk, the contamination has led to vapors traveling upward through the soil, where it can enter houses and buildings.

Location

Below is the building mitigation status map. The purpose of the map is to show which buildings are in the mitigation area, where additional investigation is needed and where long-term monitors will be installed.

Project information

General Mills, under the oversight of the MPCA, pumped and treated groundwater for 25 years at the Hennepin Avenue site to remove the TCE from it. Based on extensive groundwater testing over many years, data demonstrated that TCE concentrations in the groundwater declined and the groundwater plume has stabilized. With approval from the MPCA, the treatment systems were shut down in September 2010 and monitoring was increased to determine whether the system can remain shut down. Drinking water in the area was never a health issue because this area is served by city water and there were no wells that drew from the contaminated plume.

Soil vapor testing was required as part of this process. In October 2013, data showing TCE in soil gas samples taken on public rights of way in the area prompted the alert to property owners and residents. Vapor intrusion work is ongoing.

Next steps and timeline

In June 2021, we published the sixth five-year review report for the General Mills/Henkel Corp. Site. The purpose of the report is to assess the site cleanup activities and ensure that human health and the environment remain protected.

Site history

From 1947 to 1962, TCE and other wastes were disposed of at the site. Chemicals were placed in an “absorption pit” located in the southeast corner of the property. This was common practice at the time.

Contact

Timothy Grape
Project manager
651-757-2893