A trichloroethene (TCE) groundwater plume stretches across roughly ten square miles in Baytown Township, Washington County, Minnesota, reaching into West Lakeland Township, the City of Bayport, and the City of Lake Elmo. The plume sits in three aquifers: the Prairie du Chien, the Jordan Sandstone, and in some areas the Tunnel City. A former metalworking facility that operated in Lake Elmo from 1940 to 1968 is the primary source of contamination. The site was added to the federal National Priorities List (NPL) in 1994, which is the EPA's roster of contaminated sites that warrant formal cleanup.
Two contaminants are the focus of cleanup: TCE in groundwater across multiple areas, and carbon tetrachloride in groundwater and private wells. Both were identified because EPA determined they pose an unacceptable risk to human health or the environment. Over 900 residential water supply wells in the area are monitored, and drinking water treatment has been in operation since 2008. This includes granular activated carbon (GAC) filters on private wells and treatment systems for the City of Bayport's municipal wells. EPA has determined that human exposure is currently under control, meaning there are no unacceptable exposure pathways across the site at this time.
The site is divided into three operable units (OUs), each targeting a different area. OU 1 covers groundwater and private wells, using monitoring, carbon adsorption, and pump-and-treat methods. OU 2 addresses the Bayport municipal wells through air stripping and vertical well extraction. OU 3 focuses on the source area, using a combination of air stripping, in-situ treatment, hydraulic containment, and infiltration basins. Physical construction is not complete, and contaminated groundwater is still migrating, meaning long-term protection has not yet been achieved. A new remedial investigation of the source area began in June 2023 to collect additional data on hydrology, groundwater, and subsurface soils.
EPA and the Minnesota Pollution Control Agency (MPCA) conduct a review of the remedy every five years. The most recent review, completed in March 2022, found the remedy protective of human health in the short term. The next review is estimated between March and May 2027. The MPCA continues to monitor private wells and install GAC filters as needed. Land above the plume includes farmland, rural homes, a commercial area, Lake Elmo Airport, and developed parts of Bayport, and a convenience store and gas station currently operate at the source area property.
Community members can review site records at the MPCA's public information repository at 520 Lafayette Road North, Saint Paul, MN 55155, or by calling 651-757-2645. EPA staff are also available directly for questions about the site.
