General Mills: Detailed site and planning information

TCE was used as an industrial solvent at a former General Mills Inc., research facility at 2010 E. Hennepin Ave. in Minneapolis in the 1940s until the early 1960s. During that time, waste TCE was disposed of in a pit on the property. The contaminated site has been known about for more than 30 years.

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.

Vapor Intrusion Pathway Investigation Report, East Hennepin Avenue Site, Minneapolis, Minnesota, July 2015