Lake Elmo Private Wells: Minnesota Dept. of Health

Lake Elmo Private Wells
June 2016

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In 2004, the Minnesota Department of Health (MDH) and the Minnesota Pollution Control Agency (MPCA) learned that perfluorochemical (PFC) wastes were disposed of in the former Washington County Landfill during the 1960s to 1970s.  These wastes came from the 3M manufacturing plant in Cottage Grove.  PFCs are a class of chemicals that are used in a wide range of products that resist oil, water, stains, and heat; they move easily in the environment and do not break down. 

The MDH  Public Health Laboratory developed a method for detecting two PFCs, PFOA (perfluorooctanoic acid) and PFOS (perfluorooctane sulfonate), in drinking water and MDH and MPCA began testing for these chemicals in drinking water from private wells in Lake Elmo that were near the former landfill.  Initial sampling detected only low levels of PFOA were detected in several wells south of the landfill. However, in 2005 PFOS and PFOA were detected in most Oakdale city wells, including one near the border with Lake Elmo, which led to additional sampling that detected both PFOS and PFOA in many more wells in the Tablyn Park and Lake Elmo Heights neighborhoods.

In 2006, the list of PFCs was expanded to include five additional PFCs that were detected in the landfill.  Widespread detection of perfluorobutanoic acid (PFBA) resulted in a much larger well sampling effort throughout southwest Lake Elmo. To date, the MDH and MPCA have sampled over 400 private wells as part of this ongoing investigation of PFCs in the groundwater of western Lake Elmo. PFCs were detected in over 300 private wells, some at levels above health concern.

Environmental sampling determined that PFCs in the groundwater in Lake Elmo come from both the former Washington County Landfill and the 3M-Oakdale Disposal Site.  PFCs at the site in Oakdale enter Raleigh Creek, which flows east to the city of Lake Elmo and discharges into Eagle Point Lake in the Lake Elmo Park Reserve.  As the PFCs travel in the creek, some infiltrate into the groundwater and combine with PFCs already in the groundwater from the former Washington County Landfill.  Because of their ability to move between surface water and groundwater, PFCs are found in several of the area lakes (Eagle Point Lake, Lake Elmo, Sunfish Lake, and Horseshoe Lake).  In 2007, MDH issued a fish consumption advisory for Lake Elmo due to PFOS in some fish. See the MDH Site-specific Meal Advice for Tested Lakes and Rivers for more information.

Other areas of Lake Elmo, including the wells serving the Cimarron community and Oak-Land Junior High School have been tested by MDH and are either not affected by the PFC contamination or have shown only trace (low part per trillion) amounts of perfluorobutanoic acid (PFBA).

What is being done?

Homes in the Tablyn Park and Lake Elmo Heights neighborhoods, two areas where a majority of the private wells were impacted, were connected to the Lake Elmo municipal water supply in 2007. 3M provided the city a grant for the water extension project, and paid for two years of the residents’ water bills. The private wells that served these homes were sealed to prevent future exposure to the PFCs.

MDH and MPCA staff continue to monitor private wells in the Torre Pines, Parkview, Stonegate, Whistling Valley, and other nearby neighborhoods. How often a well is sampled is based on the concentration of PFCs detected in that well and nearby wells. All homes where PFCs exceed MDH drinking water criteria are provided with GAC filter systems that are monitored and maintained by MPCA.  Wells located along the edges of the PFC plume are also sampled to monitor any changes in the size and concentration of the plume.

In 2008, 2010, and 2014, MDH completed biomonitoring studies of selected residents in Cottage Grove, Lake Elmo, and Oakdale who were known to have been exposed to PFOA and/or PFOS in their drinking water. The average concentration of PFCs in the participants' samples were higher than the averages for the general U.S. population. The studies also showed that over time, as the participants drink treated water, the PFC concentrations in their bodies decreased. More information about the biomonitoring studies can be found at PFC Biomonitoring: East Metro.

In 2009-2011, MPCA completed cleanup actions at the former Washington County Landfill.  This consisted of excavating all of the waste at the site and placing it in triple-lined containment cells. Information about the landfill cleanup can be found on the MPCA Web page Washington County perfuorochemical(PFC) waste sites.

In general, the PFC plume in Lake Elmo appears to be stable and does not appear to be changing or spreading. However, wells nearest the former Washington County Landfill did experience a temporary increase in some PFC concentrations after the groundwater pump-out system at the landfill was shut off to allow for cleanup activities to occur. Since then, concentrations in those wells have started to decrease over time.

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Next steps

MDH and MPCA will continue testing of private wells to monitor levels PFCs. Alternate safe drinking water will be provided if the drinking water testing results exceed health guidelines. Health guidelines can be found on the MDH Perfluorochemicals and Health webpage.

MDH will continue to provide updates when there is new information or developments.

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Updated Friday, June 17, 2016 at 10:14AM