A public meeting on Wednesday, Oct. 24, 2018, veered into highly scientific and technical territory at times on a new issue related to the ACO Products (Pittsfield Products) groundwater contamination from decades ago. The main contaminant from the groundwater plume, TCE (trichloroethylene), has been detected in soil gas wells in certain locations between ACO’s location on Hamburg Street and North Dexter Street to North Mill Street (see map). MDEQ has contacted homeowners in areas where these monitoring wells showed levels of TCE exceeding the established standards, in order to install “vapor pins” to conduct testing of indoor air quality.
Hosted by the Village of Pinckney, multiple representatives from MDEQ outlined the history of the ACO contamination, which resulted in the establishment of the village’s municipal water supply system in the early 1990s due to widespread contamination of household wells. ACO entered into a consent agreement in 1995 to clean up the site and has treated millions of gallons of groundwater since then, removing the TCE before releasing the treated water back into the ground.
However, TCE vaporizes from the groundwater into the soils and can rise through foundation slabs depending on conditions. High levels at the soil gas wells doesn’t necessarily mean all the homes in the area risk indoor air quality problems, but they are an indicator that additional testing is needed.
Nineteen homeowners (indicated in green on the map) have been contacted by MDEQ to request permission to enter their homes and install vapor pins — small, screw-like devices that are inserted into foundation slabs that allow for the collection of air samples. MDEQ representatives said four samples would be taken at various times since TCE levels can vary with weather and temperature. If readings come back above the allowable level, a portable carbon-based mitigation unit will be installed in the home to purify the air while a permanent system, similar to those used to remove radon, is installed. Costs will be covered by MDEQ.
Vapor pins, and a soil gas well, have already been installed at Light of the World Academy at Pearl and Hamburg Street. The school is in the middle of the groundwater plume, although thus far results have shown no contamination in the indoor air of the school. That soil gas well, and two additional new wells at Fireman’s Park (next to ACO) and on Hamburg Street between William and Magic Streets, will be tested again on Thursday, Oct. 25.