MINNEAPOLIS, Minn. - Testing has been completed in more than 90 percent of the homes and buildings in the Minneapolis Como neighborhood study area where the possible presence of soil vapor is being assessed by General Mills.
Of 182 properties participating in the study area, 166 homes and buildings have now been sampled. One-third (55) of those properties have been found to have trichloroethylene (TCE ) levels below the very protective screening threshold set by the Minnesota Pollution Control Agency (MPCA).
Approximately two-thirds (111) of the properties sampled have been offered vapor ventilation systems. In the study, if TCE is present in the soil vapor at levels above the MPCA screening threshold, property owners are offered a vapor ventilation system at General Mills’ expense. Such systems are a proven solution to the issue of vapor intrusion, according to the Minnesota Department of Health (MDH).
Of the 111 properties offered ventilation systems, nearly two-thirds (69) already have their systems installed, with additional installations being completed weekly.
The study, announced Nov. 7, is assessing whether TCE is present in the soil vapor beneath the basement floor or slab of homes and buildings in the study area. TCE may be present as a result of historic waste disposal activities from the 1940s until the early 1960s at a site formerly owned by General Mills. TCE, a common industrial solvent and degreaser, may also be found in household products such as wood finishes, adhesives, paint removers, lubricants, and cleaners.
Soil in the area of the former disposal site was excavated and removed as part of extensive cleanup activities in the early 1980s. Extraction and treatment of shallow-level groundwater (non-drinking water) continued thereafter for 25 years. Drinking water supplies were not impacted.
In 2012, at the request of the MPCA, General Mills began investigating the potential for TCE vapors from the shallow groundwater to accumulate in the soil gas. Soil vapor testing was conducted, and in September 2013, TCE was found to be present in several soil gas samples taken on public rights-of-way in the area, prompting the study. Testing and mitigation is conducted by General Mills, under the oversight of the MPCA.
Additional homes have been added, as anticipated, as the study has progressed based on the data collected. Access agreements have been sought for an additional 128 properties, and 98 agreements have been received to date. Seventy-six of those properties have already been sampled, with 17 testing above the MPCA screening threshold. Those 17 were offered vapor ventilation systems. Fifty-eight properties tested below the screening threshold set by MPCA, with one result still pending.
Representatives from the MPCA, MDH and General Mills have continued to hold informational meetings for area residents. Another “open house” type meeting is scheduled for March 25, enabling residents to come at any time during the time listed.
The next scheduled “open house” will be held:
Van Cleve Recreation Center (901 15th Ave SE, Minneapolis)