Minneapolis environmental study announced
On Thursday, November 7, the Minnesota Pollution Control Agency (MPCA) and the Minnesota Department of Health (MDH) announced a study assessing the potential presence of soil vapors under homes and buildings near 2010 East Hennepin Avenue in Minneapolis – the site of a former General Mills research center.
The study will test for the possible presence of trichloroethylene (TCE) in the soil gas. In October, the decision was made to alert residents to the findings of TCE in soil gas on public rights-of-way in the Como neighborhood in Minneapolis. No drinking water sources are affected.
Further sampling will determine whether soil vapors may be present under homes and buildings. No testing has been done in area homes, but officials at the Minnesota Department of Health (MDH) and the Minnesota Pollution Control Agency (MPCA) expressed concern that TCE could be present and that sampling should be done.
The source of the potential vapor intrusion in the area is related to historic waste disposal activities at 2010 East Hennepin Avenue in Minneapolis, a site owned and operated by General Mills from approximately 1930 until 1977. Beginning in the 1940s, until the early 1960s, solvents were disposed of in a manner customary for the times in a soil absorption pit located in the southeast portion of the property. It wasn’t until decades later that people realized the problems with such practices.
Discovery of trichloroethylene (TCE), a commonly-used cleaning solvent and degreaser, in the former disposal area led to extensive clean-up activities at the site in 1981. Work was funded by General Mills, under MPCA oversight.
General Mills began treating shallow-level groundwater in the area in 1984. Based on extensive groundwater testing and treatment by General Mills over 25 years, data demonstrated that TCE concentrations significantly declined and the groundwater plume had stabilized. With approval from the MPCA, the shallow-level groundwater treatment systems were shut down in September 2010, moving the site toward closure.
Soil vapor testing was required as part of that process, and confirmation of the presence of TCE above MPCA screening levels in soil gas samples on public rights-of-way in the area prompted this announcement.
Letters were mailed to area homes and businesses by the MPCA on Nov. 6. Two community open houses will also be held in the neighborhood at Van Cleve Recreation Center, 901 15th Avenue SE, Minneapolis, on Tuesday, November 12, 2013, from 12:30 – 3 p.m., and again from 5:00 – 7:30 p.m.
At the open houses, homeowners will be informed of the testing locations and procedure, and be able to meet one-on-one with representatives of the MPCA and MDH. Agency representatives will also discuss the health risks of TCE, and allow residents to sign-up for sampling, which could begin as soon as the week of Nov. 18.
Project teams will visit homes and buildings in the study area seeking access to complete the soil gas testing. The potential study area encompasses approximately 200 area homes.
Vapor ventilation systems, which are the same as radon mitigation systems, will be offered and installed at the company’s expense, in any home found to have TCE levels above the level set by MPCA. Such systems are a proven solution to radon and vapor intrusion problems. Homes with existing radon mitigation systems are already mitigated for TCE.
Testing will be done at no cost to residents or property owners, and vapor intrusion mitigation systems will also be offered and installed at no cost in affected homes. A map of the study area and other additional resources are available on the MPCA website.
Minnesota Pollution Control Agency contacts
Fred Campbell, Site Remediation, 651-757-2260, email@example.com
Hans Neve, Site Remediation, 651-757-2608, firstname.lastname@example.org
Minnesota Department of Health contacts
Rita Messing, 651-201-4916 or Emily Hansen, 651-201-4602
Site Assessment and Consultation Unit, 651-201-4897 or 800-657-3908