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PFAS in Groundwater

Updated Dec. 11, 2020

Note: The water the city delivers to customers continues to meet all state and federal standards and guidelines for PFAS.

On Sept. 10, the Minnesota Pollution Control agency (MPCA) and the Department of Natural Resources (DNR) announced a $700 million long-term drinking water protection plan for per- and poly-fluoroalkyl substances (PFAS) in the Twin Cities East Metropolitan Area, including Woodbury. The agencies revealed three conceptual drinking water supply plan (CDWSP) options that would provide safe and sustainable drinking water. 

The city provided feedback to the state on several items in the draft CDWSP options. While this input is technical in nature, there are two items the city is requesting be addressed that are critical and may be of particular interest to residents:

  1. Treating the water to the lowest feasible PFAS health index threshold possible should be a priority; and
  2. Settlement funds should be properly directed and prioritized first to capital and long-term operations and maintenance for drinking water treatment and to keep local water bills affordable for residents and businesses.

The public can learn more about the options on the 3M Settlement website. Private well owners can use the MPCA interactive map to see the draft long-term drinking water options for individual private wells.

Thank you to all residents who took the time to submit feedback during the comment period. The MPCA and DNR expect to finalize the East Metro drinking water plan in 2021. The city will continue to provide updates as more information becomes available.

Temporary water treatment plant 
The City of Woodbury’s new temporary water treatment plant began operating in June 2020. The facility, located near the intersection of Valley Creek Road and Tower Drive, is treating water from four wells to meet water quality standards and guidelines for per- and polyfluoroalkyl substances (PFAS) using granular activated carbon. 

Activated carbon is commonly used to adsorb natural organic compounds, taste and odor compounds, and synthetic organic chemicals in drinking water treatment systems. Adsorption is both the physical and chemical process of accumulating a substance, such as PFAS, at the interface between liquid and solids phases. Activated carbon is an effective adsorbent because it is a highly porous material and provides a large surface area to which contaminants may adsorb. Activated carbon is made from organic materials with high carbon contents such as wood, lignite, and coal; and is often used in granular form called granular activated carbon (GAC).

GAC has been shown to effectively remove PFAS from drinking water when it is used in a flow through filter mode after particulates have already been removed. GAC can be 100 percent effective for a period of time, depending on the type of carbon used, the depth of the bed of carbon, flow rate of the water, the specific PFAS you need to remove, temperature, and the degree and type of organic matter as well as other contaminants, or constituents, in the water. 

The temporary water treatment facility is expected to be in operation until a long-term water treatment solution can be implemented in the next five to seven years. Funds for the long-term solution are expected to be available from the $720 million settlement the state received from 3M in 2018. 

Seven of the city’s 19 wells were removed from service since 2017 due to PFAS levels that were above federal and state water quality standards and guidelines. Bringing four of the seven wells back into service allows the city to meet the increased demand for water during the summer months. The remaining three wells will remain out of service at this time.

Temporary Treatment Facility June 2020The temporary water treatment plant, which typically takes about 18 months to two years to construct, was completed in about five months. In order to meet peak summer demand, it was critical the temporary treatment facility was operational as quickly as possible. The city would not be operating the facility today without the work and cooperation of the State of Minnesota, 3M, the City Council, numerous city staff, our engineering consultant teams, and the construction expertise of the project contractor.

About PFAS
The 3M Company made PFAS at its Cottage Grove facility from the late 1940s until 2002. PFAS wastes were disposed of at multiple sites in Washington County. The source of the PFAS in Woodbury’s groundwater has been identified as these disposal sites.

Funding for the Woodbury temporary water treatment plant is provided through the 2018 settlement agreement between the State of Minnesota and 3M. This arrangement includes a $40 million provision for temporary facilities meeting the requirements of the 2007 settlement agreement between the same two parties.

If you have questions about the city’s water system and the impact of PFAS, contact Public Works at 651-714-3720 or

PFAS Resources

Learn more about PFAS in groundwater

PFAS Monitoring Results in Woodbury's municipal wells

MDH Well Health Risk Advisory Map

Remediation Activities
In 2011, the Minnesota Pollution Control Agency (MPCA) completed remediation activities at these sites to reduce the amount of pollutants released from these sites in the future.

3M, under direction from the MPCA, continues active site remediation. For the Woodbury site, remaining contamination is captured by pumping approximately 1.25 billion gallons of water annually to a treatment plant and discharging it to the Mississippi River.

Visit the MPCA website for more information about the remediation activities.

Private Water Supply Wells
As a result of the EPA’s new guidance and MDH updated HBV for PFOA and PFOS, MDH is sampling private wells within Washington County and will issue additional drinking water advisories as needed. Until their private wells are tested, residents who have concerns about their health can take steps to reduce their potential exposure to PFAS. Information on point-of-use filters and other steps people can take in their homes can be found on the MDH website.

Private water well owners or residents interested in treating the water after it reaches their home can learn about home treatment options at

Residents who have questions about their private water supply well and whether it is impacted by this change should contact MDH.

June 12 Update: Temporary treatment facility nears completion

April 13 Update: Increased water restrictions likely until temporary treatment facility is complete

March 4: MPCA and DNR listening and information sessions presentation

Feb. 21 Update: Seventh Woodbury well has PFAS levels above water quality limits

Jan. 8, 2020 Update: City begins work on temporary water treatment facility

Oct. 24 Update: Public Meeting held at Woodbury High School

Oct. 18, 2019 Update: Sixth Woodbury Well has PFAS levels above health risk limit

Aug. 28, 2019 Update: Expedited project awarded to and accepted by Woodbury

April 3, 2019 Update: Minnesota Department of Health issues new Health-Based Guidance Values

March 2, 2018 Update: $850 million settlement provides funding for cleaning up drinking water