Baytown Township Groundwater Contamination Site: Minnesota Dept. of Health

Baytown Township Groundwater Contamination Site

This page provides information about public health issues related to TCE contamination in the Baytown Township Groundwater site in Washington County, Minnesota. Trichloroethylene, also known as trichloroethene or TCE, is a chemical solvent often used for degreasing metal parts. It was first found in the groundwater in the area in 1987, and the site is listed as a state and federal Superfund site. TCE is a human carcinogen and has been linked to adverse immune system effects.

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Trichloroethylene (TCE) is one of a class of chemicals called Volatile Organic Compounds (VOCs). VOCs are a large class of chemicals that have been used throughout the United States since the 1940s by industry, commerce, households and the military. Because they were commonly used for residential and industrial purposes, and stay in the environment for a long time, VOCs are a threat to ground water quality.

For more information about TCE, see:

Trichloroethylene (TCE) and Your Health

TCE in Drinking Water (PDF)

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))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.).

For information about MPCA activities at the site including current maps, see MPCA's page Baytown Township Groundwater Contamination Site.


Site Activities

TCE was first found in the groundwater in the Baytown Township area in 1987. The Baytown Groundwater Contamination Site is listed as a state and federal Superfund site.

TCE has been detected in approximately 400 private wells, primarily in Baytown and West Lakeland townships, but also in Bayport. Since 2002, the MPCA has provided bottled water and/or whole-house granular activated carbon (GAC) filters to every residence where TCE concentrations were at or above the HRL of 5 µg/L.

The Minnesota Pollution Control Agency (MPCA) has been the lead agency, in cooperation with the U.S. Environmental Protection Agency, in investigating and cleaning up the source of the TCE. MPCA also oversees the sampling of private wells in the area and provides treatment systems for private wells that exceed the state’s health based guidance. For more information about MPCA activities, see Baytown Township Groundwater Contamination Site.

MDH is responsible for reviewing private well sample results and issuing drinking water advisories, as needed. MDH also samples public water supply wells in the area.

Timeline

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.

TCE first found in the groundwater in the Baytown Township area.

MDH activity at the site increased dramatically in February 2002 when the agency changed its health advice for TCE from 30 micrograms per liter (µg/L)to 5 µg/L, based on new information on its toxicity. It is known that exposures to TCE did occur as a result of the Baytown Ground Water Contamination Site.

In 2004, MDH completed a report on the site, known as a Public Health Assessment that describes activities at the site at that time and MDH's recommendations to protect public health. The MDH concluded that there was no apparent public health hazard because exposure to TCE above the HRL of 5 µg/L was being prevented by use of whole-house GAC filtration units on private wells, and because overall levels of TCE in the Bayport municipal system were below regulatory and health-based standards in place at that time. To view the 2004 public health assessment and recommendations please see the Public Health Assessment for the Baytown Groundwater Contamination Site 2004 (PDF).

In 2005, MDH’s Well Management program expanded the boundaries of the existing Special Well Construction Area (SWCA). New wells constructed within this area are subject to special restrictions regarding construction and sampling requirements. State law also requires that, during a property sale, the owner must disclose that their property is located within a SWCA. For more information about the SWCA, see the Baytown Special Well Construction Area Update (PDF).

Bayport municipal well #2 exceeded the federal Maximum Contaminant Level (MCL) of 5 µg/L in 2005. As a result, the MPCA constructed a water treatment system that removed TCE from the water pumped from this well. At this time, most of the drinking water for Bayport comes from Well #2.

In 2013, MDH re-evaluated the current Health Risk Limit (HRL) of 5 micrograms per liter (µg/L), which was based on the U.S. Environmental Protection agency’s Maximum Contaminant Level (MCL). This re-evaluation was conducted to ensure the MDH guidance was based on the most recent toxicological studies and scientific methods, and resulted in an updated Health Based Value (HBV) of 0.4 µg/L.

For more information about the updated Health Based Value, please see the Technical and Application Information for Trichloroethylene (TCE) page. For more on the health based value history and process, please visit the Guidance Values and Standards for Contaminants in Drinking Water page.

In 2013 and 2014, the MPCA sampled a large number of private wells to identify those that exceed the new HBV of 0.4 µg/L. MDH has reviewed the new data and issued well advisories, as needed. For more information about MPCA activities at the site, see MPCA's Baytown Township Groundwater Contamination Site page.

TCE concentrations in Bayport municipal wells #3 and #4 have been increasing over time, with the most recent concentrations being 4.3 and 2.9 µg/L respectively. In 2015, the Minnesota legislature approved bonding funds that enabled the city and MPCA to connect well #3 to the treatment plant. Wells #2 and #3 are now the primary water supply wells and the treated water from them contains no detectable TCE; well #4 is used as an emergency back-up well.

MDH will review all of the data and prepare a Site Review and Update report. MDH’s Well Management program will also review the data and determine whether the boundaries of the SWCA need to be expanded.

State and local government representatives will also consider what, if any, alternate, long-term solutions are available for providing a clean water supply to the Baytown-West Lakeland Township area. Bayport city officials are already working with MPCA and MDH to explore options for reducing TCE levels in their water supply.

*Properties that were platted after April 9, 2002 are not sampled by the MPCA and are not eligible for a state-provided GAC filter system. These properties are governed by specific township ordinances. For more information on these ordinances, residents should contact their township offices.

Well Water Testing

The MPCA samples all of the wells within the area of TCE contaminated groundwater (with the exception of wells on properties platted after April 9, 2002) and a select number of wells outside the area of contamination to track the edges of the plume. The sampling frequency of a well is based on the concentration of TCE in the water; wells with higher TCE levels are sampled more often than those with lower levels.

Residents who are not included in the MPCA’s groundwater sampling program, or who want their water tested sooner than MPCA is able to collect a sample, may contact Washington County and pay to have their water sampled. These samples will be analyzed by the Minnesota Public Health Laboratories and the results reviewed by MDH staff, who then send the results in a letter. For more information on how to request a sample, see Washington County's Water Tests page or download a Washington County VOC Sampling Request Form (PDF).

Updated Wednesday, 07-Aug-2019 13:27:36 CDT