Hazardous Sites and Substances in Minnesota
Baytown Township Groundwater Contamination Site
The source of the TCE in the groundwater in the Baytown-West Lakeland Township area is believed to have been a former metal working facility in Lake Elmo that operated from 1940 to 1968 on the property where Hagberg’s Market is now located. TCE released at that site moved downward through the sand and gravel beneath the site, into the bedrock, and then east toward the St. Croix River, where groundwater in this part of Washington County discharges.
In most of the area of the TCE plume, the top layer of bedrock is the Prairie du Chien Group (a limestone-dolomite formation), which in turn is underlain by the Jordan Sandstone. These two water-bearing bedrock units are the main aquifers used by drinking water wells in the area, although some newer wells have been drilled even deeper into the Franconia Sandstone (which also known as the Tunnel City group). As the TCE moved away from the source area, it also moved progressively downward into each of these aquifers. For example, although TCE has not been detected in Franconia wells near the Lake Elmo Airport, it is detected in this aquifer closer to the river.
The area of groundwater contaminated by TCE covers approximately 7 square miles. (See TCE Distribution - Most Recent Samples Map (PDF: 2,082KB/1 page)) The highest TCE concentrations are in the shallow groundwater near the site and decrease with distance from the source area as the TCE spreads out into a V-shaped plume. This plume has changed very little in terms of shape, size, or concentration since the state began sampling groundwater in this area in the late 1980s. However, since the MPCA began cleanup activities at the source area, monitoring wells near the source and at the Lake Elmo Airport have begun to show decreasing TCE concentrations. By preventing more TCE from moving off-site from the source area, the cleanup system is essentially “starving” the plume, which over time should decrease in size and concentration, but this will likely take several decades.
In general, the TCE concentrations in most of the wells in the Baytown Groundwater Contamination Area appear to be stable or slightly decreasing. However, there are exceptions. Slightly increased concentrations have been observed in some Prairie du Chien wells near the center of the plume (between 30th and 40th Streets N. and west of Osgood Avenue) and many Jordan wells in the east and southeast portions of the plume (roughly between 21st and 34th Streets N. and east of Oakgreen Ave.).