Hazardous Sites and Substances in Minnesota
Lake Elmo Private Wells
June 2008

Background
In 2004, the Minnesota Department of Health (MDH) Public Health Laboratory developed a method for detecting two PFCs, PFOA (perfluorooctanoic acid) and PFOS (perfluorooctane sulfonate), in drinking water and the MDH and the Minnesota Pollution Control Agency (MPCA) began testing drinking water from private wells in Lake Elmo that were near the former Washington County Landfill for these chemicals.

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. Other areas of Lake Elmo, including the city’s municipal wells and 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).

Homes in the Tablyn Park and Lake Elmo Heights neighborhoods, two areas where a majority of the private wells were impacted, have been connected to the Lake Elmo municipal water supply. 3M provided the city a grant for the water extension project, and will pay 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. Monitoring includes quarterly, semi-annual, or annual sampling based on the concentration of PFCs detected in each well. Wells located within and along the edges of the PFC plume are also sampled to monitor any changes in the size and concentration of the plume. So far, the plume appears to be stable and does not appear to be changing or spreading.

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Health-Based Exposure Limits for PFCs
The discovery of PFCs in the environment is recent, and federal EPA standards do not currently exist. Scientists around the world are studying the way PFCs act in the environment, and effects on laboratory animals and on workers who were exposed through manufacturing processes. As these studies become available, MDH scientists review them and evaluate the implications to ensure that the actions we take are protective of people’s health.

In May 2009, MDH issued Health Risk Limits (HRLs) for PFOA and PFOS of 0.3 micrograms per liter (ug/L). A Health Risk Limit is the amount of a chemical in drinking water that MDH scientists consider safe for people to drink daily for a lifetime. In February, 2008, MDH issued a Health-Based Value (HBV) for PFBA of 7 ug/L. A Health-Based Value is similar to a HRL, but has not been formally promulgated through the rule-making process.

To date, 56 private wells outside of the new city water service area have levels of PFCs alone or in combination that are above the MDH HRLs or HBV. Those homes have been provided with an activated carbon filter system by the MPCA to remove the PFCs from their well water, or are being provided with bottled water. The MDH and MPCA have tested the GAC systems and the test results show that the GAC filters are effective at removing the PFCs.

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. If you have questions, please feel free to contact any of the staff listed below. MDH will continue to provide updates as new information and developments.

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Additional Information

City of Lake Elmo

Public Health Assessment: Perfluorochemical Contamination in Lake Elmo and Oakdale, Washington County, Minnesota

Water Treatment Using Carbon Filters: GAC Filter Information

Special Well and Boring Construction Areas

Minnesota Pollution Control Agency: Perfluorochemicals

Environmental Protection Agency: Perfluorooctanoic Acid (PFOA) and Fluorinated Telomers

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For more information, please contact us.

Updated Thursday, 15-Dec-2011 08:42:20 CST