May 02, 2014
Minneapolis soil vapor testing nearing completion
MINNEAPOLIS, Minn. - Testing is nearing completion in the Minneapolis Como neighborhood study area where the possible presence of trichloroethylene (TCE ) in soil vapor is being assessed.
Of 185 properties participating in the initial study area, 181 homes and buildings have now been sampled. Fifty-eight (58) properties have been found to have TCE levels below the very protective screening threshold set by the Minnesota Pollution Control Agency (MPCA). One hundred twenty-three (123) properties had levels above the screening threshold, and have been offered vapor ventilation systems. Ventilation systems have been installed in 105 properties to date, with additional installations being completed weekly. Such systems are a proven solution to the issue of vapor intrusion, according to the Minnesota Department of Health (MDH).
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 area. Testing and mitigation is conducted at General Mills’ expense, under the oversight of the MPCA.
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. Extraction and treatment of shallow-level groundwater (non-drinking water) in the area began in the early 1980s and continued for 25 years. Drinking water supplies were not impacted. A common industrial solvent and degreaser, TCE may also be found in household products such as wood finishes, adhesives, paint removers, lubricants, and cleaners.
As anticipated, additional homes have been added to the study area as data is collected. As a result, access agreements have also been received for an additional 128 properties, with 116 of those properties having already been sampled. Thirty-four (34) of these additional properties tested above the MPCA screening threshold, and were offered vapor ventilation systems. Eighty (80) properties tested below the screening threshold set by MPCA, with two results still pending.