Healing from Groundwater Contamination in Washington County

In the next few weeks, select residents in Oakdale, Lake Elmo and Cottage Grove will receive letters in the mail from the Minnesota Department of Health asking them to participate in an important study tracking the impacts of groundwater contamination in Washington County. Titled PFC3 (East Metro PFC3 Biomonitoring Project), the study is part of a larger Department of Health effort with the unsettling name Minnesota Biomonitoring: Chemicals in People.

During the 1940’s and 1950’s, 3M disposed of chemical waste at three different locations in Oakdale along Hwy 5, just west of I 694. After the Minnesota Pollution Control Agency found a variety of hazardous substances in the soil and groundwater near these sites in the early 1980’s, 3M removed contaminated soil, installed groundwater monitoring wells, and constructed a pump-out system to remove pollutants from portions of the shallow groundwater aquifer. During this time, several homes with private wells were also connected to Oakdale’s municipal water supply in order to provide residents with safe drinking water.

Unfortunately, however, these measures did not completely resolve the problem. In the early 2000’s, 3M and the Department of Health detected perfluorochemicals (PFCs) in the groundwater collected from the monitoring wells and determined that these PFCs had contaminated private wells in western Lake Elmo as well as a few of Oakdale’s municipal wells. In response, the city installed a large carbon filtration system at its water plant in 2006 and 290 Lake Elmo homes with private wells were connected to the city water supply. Some homeowners in Lake Elmo with private wells also installed carbon filtration systems in their homes. Tests shows that the filtration systems are effectively removing PFCs and that the water is now safe to drink. 

Meanwhile, 3M continued to produce PFCs for non-stick cookware and stain resistant fabrics from the 1940’s until 2002. During this time, they disposed of waste containing PFCs on 3M properties in Cottage Grove and Woodbury, as well as at the old Washington County Landfill in Lake Elmo, which was in operation from 1969-1975. As in Oakdale, PFCs and other contaminants have since been found in the groundwater near these sites and some homes with private wells have had to connect to municipal water supplies or install filters in order to access clean water.

In 2008, the MN Department of Health initiated a study to determine if long-term residents of Oakdale, Lake Elmo and Cottage Grove were impacted by drinking the PFC contaminated groundwater before carbon filters were installed in 2006. They collected blood samples from approximately 200 adults and found that all had detectable levels of PFCs in their blood and that most had PFC levels higher than those found in the general U.S. population. A follow-up study conducted in 2010 with 164 of the original study participants found that PFC levels in most people’s blood had gone down, by 26% for PFOS, 21% for PFOA, and 13% for PFHxS.

This year, the Department of Health will follow up with the original study participants to determine if PFC levels in their bodies have continued to decline over the years. At the same time, they hope to recruit up to 200 new residents who have moved to Oakdale since 2006 to determine if PFC levels in their bodies are comparable with the general U.S. population, as would be expected now that Oakdale’s municipal water supply is treated and safe to drink. Next week, the Department of Health will send letters with questionnaires to some Oakdale homes and will use the responses to randomly select new study participants. Volunteers will be asked to give a small blood sample at the HealthEast Clinic in Oakdale and will be compensated for their time.

Because PFCs are relatively new, researchers do not know how much of a risk they pose for human health. To be safe, however, the Department of Health has set health risk limits for PFCs in drinking water and the Minnesota Pollution Control Agency will continue to work with Washington County, as well as local businesses and communities, to monitor groundwater quality and protect people in areas with contaminated water supplies. The project coordinators hope that many Oakdale residents will participate and return their household surveys so that they will be able to determine if PFCs are still affecting people in the community.

For more information about the PFC3 biomonitoring project and other biomonitoring projects in Minnesota, go to http://www.health.state.mn.us/biomonitoring.