Perfluoroalkyl Substances (PFAS) Sites in Minnesota
Perfluoroalkyl Substances (PFAS) are also referred to as Perfluorochemicals (PFCs)
The Minnesota Department of Health (MDH) and Minnesota Pollution Control Agency (MPCA) have investigated a number sites across the state where PFAS were released to the environment.
The MPCA also monitors PFAS in the general environment of Minnesota. This type of monitoring is referred to as ambient monitoring and you can learn more about it on the MPCA's website.
East Metro Sites
In the eastern Twin Cities metropolitan region ("East Metro"), these sites include the 3M Cottage Grove manufacturing facility and large waste disposal facilities where PFAS-bearing wastes were disposed.
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 PFAS 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 PFAS concentrations in their bodies decreased. More information about the biomonitoring studies can be found at PFC Biomonitoring: East Metro.
The 3M Company produced Perfluoroalkyl Substances (PFAS) at its Cottage Grove facility from the late 1940's until 2002. Perfluorooctanoic acid (PFOA) was the main type of PFAS made at this site. PFOA is used in the making of products that resist heat, oil, stains, grease and water. Common uses include nonstick cookware, stain-resistant carpets and fabrics, and other industrial applications.
For a time, wastes from the production process were disposed on site in a specially prepared pit; there may be other disposal sites as well. The water treatment plant on site that processed water from production activities did not remove PFAS, so PFAS were in the waste water that went into the Mississippi River. Some sludge left over from the water treatment process also contained PFAS and was disposed on site. On the west side of the site, firefighting foams containing PFAS were used in training exercises. PFAS may also have been released into the air.
PFAS at 3M-Cottage Grove
Environmental testing shows that the groundwater beneath the 3M Cottage Grove site is contaminated with PFOA, and other PFAS including perfluorooctane sulfonate (PFOS) and perfluorobutanoic acid (PFBA). In some areas, the levels of PFAS exceed the Minnesota Department of Health (MDH) drinking water criteria. Groundwater beneath the site flows south and discharges to the Mississippi River. Sampling of river sediments near the site and the water within those sediments detects PFAS at levels of concern for humans and wildlife, but concentrations in the river water are much lower due to dilution.
PFAS have been detected at concentrations below levels of health concern in the Cottage Grove municipal wells and private drinking water wells near the 3M-Cottage Grove facility. However, groundwater in this area flows south toward the Mississippi River. The sources of the PFAS in the city and private wells are believed to be the 3M-Woodbury Disposal Site and possibly also the 3M-Oakdale Disposal Site and Washington County Landfill in Lake Elmo. MDH and MPCA continue to monitor city and private wells throughout south Washington County and provide treatment systems for wells that exceed MDH drinking water criteria.
What Was Done
Workers at the facility were exposed to PFAS in the course of their work and also through the facility's water supply. 3M now treats their drinking water with a GAC filter system. 3M has been monitoring PFAS in the workers' blood since the 1970's. Epidemiological studies of these workers show no impact of PFAS on worker mortality.
An extensive system of wells contains and collects much of the contaminated groundwater from under the site so that the wastewater treatment plant can process it. This system was expanded in 2010 and a large granular activated carbon (GAC) filter system was added to the plant to remove PFAS from the water before it goes into the river. Further upgrades to this groundwater pump-out system are planned to try to stop all PFAS from leaving the site.
In 2009-2011, 3M excavated the former waste disposal areas and the sediments in a cove next to the river through which PFAS-contaminated wastewater flowed in the past. The soil and sediments were disposed of off-site in lined containment facilities. More information about the site and 3M cleanup actions can be found on the MPCA webpage Perfluorochemical (PFCs).
The 3M Woodbury Site is located approximately six miles south of Interstate 94 along the border of Cottage Grove and Woodbury (between Co. Rd 19/Woodbury Drive and Lamar Ave just north of 67th Street). Since 1992, the site has been in the Voluntary Investigation and Cleanup (VIC) Program at the Minnesota Pollution Control Agency (MPCA).
The site consists of three disposal locations used for disposal of solid waste, industrial solvents and acids from 3M's Cottage Grove and Saint Paul manufacturing facilities during the 1960s. Woodbury and Cottage Grove residents also used the site for dumping municipal waste (such as household, automotive, construction, and commercial debris). In 1966 isopropyl ether, an industrial solvent, was discovered in a shallow well on a nearby property. This prompted further investigation of the site and more extensive well testing for area residential wells. A variety of hazardous substances, particularly volatile organic compounds (VOCs), were found at the site in both the soil and groundwater. However, no other drinking water wells were found to be contaminated.
PFAS at 3M Woodbury
In spring 2005, low levels of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) were detected in the groundwater pump-out system at the 3M Woodbury site, prompting an investigation of nearby residential wells by MDH and MPCA to determine if PFAS were migrating from the dump in groundwater. PFOS and PFOA were not detected in any of the private wells.
However, in spring 2006, the MDH Public Health Laboratory expanded its PFAS analytical method to include five additional PFAS. Of the five, perfluorobutanoic acid (PFBA) was found to be widespread in the groundwater south of two other 3M waste disposal sites, the former Washington Co. Landfill in Lake Elmo and the Oakdale Dump, and extending south into the city of Woodbury. In late 2006 to early 2007, additional sampling of monitoring wells at the 3M-Woodbury Disposal site and private drinking water wells near the site also detected PFBA.
What Was Done
MDH and MPCA worked together to sample over 1,100 private wells in south Washington County to determine the extent of the groundwater contamination and identify any wells that exceed MDH drinking water criteria. Over 26 drinking water advisories have been issued to private well owners in Cottage Grove (primarily in the area south of Highway 10 and west of the 3M-Cottage Grove plant).
MDH and MPCA continue to monitor approximately 300 wells in this area annually to track the PFAS plume. In general, PFAS concentrations have remained quite stable over time. How often a well is sampled is based on the concentration of PFAS detected in that well and nearby wells. In some areas with very low PFAS levels, two or three wells are used as "sentries" to track water quality, rather than sampling all of the wells in that area. All homes where PFAS 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 PFAS plume are also sampled to monitor any changes in the size and concentration of the plume.
In 2009-2011, 3M completed additional cleanup actions at the 3M-Woodbury Disposal Site. This included excavation of contaminated soils and off-site disposal in lined containment facilities, improvements to the pump-out system to ensure contaminated groundwater is contained on-site, and installation of additional wells to monitor the groundwater at the site. More information about these actions can be found on the MPCA webpage Perfluorochemical (PFC) waste sites.
Currently, the site groundwater pump-out system is extracting over 4 million gallons of groundwater per day. As the population of south Washington County increases, so does the demand for water. 3M is working with MPCA, MDH, and the cities of Cottage Grove and Woodbury to evaluate whether the amount of water being pumped at the site can be reduced while still keeping PFAS from moving away from the site.
BackgroundIn 2004, the Minnesota Department of Health (MDH) and the Minnesota Pollution Control Agency (MPCA) learned that Perfluoroalkyl Substances (PFAS) waste was disposed of in the former Washington County Landfill during the 1960s to 1970s.
PFCS at Lake Elmo Private Wells
The MDH Public Health Laboratory developed a method for detecting two PFAS, 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 PFAS was expanded to include five additional PFAS 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 PFAS in the groundwater of western Lake Elmo. PFAS were detected in over 300 private wells, some at levels above health concern.
Environmental sampling determined that PFAS in the groundwater in Lake Elmo come from both the former Washington County Landfill and the 3M-Oakdale Disposal Site. PFAS 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 PFAS travel in the creek, some infiltrate into the groundwater and combine with PFAS already in the groundwater from the former Washington County Landfill. Because of their ability to move between surface water and groundwater, PFAS are found in several of the area lakes (Eagle Point Lake, Lake Elmo, Sunfish Lake, and Horseshoe Lake). In 2007 and 2018, MDH issued fish consumption advisories for Lake Elmo due to PFOS. 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 PFAS contamination or have shown only trace (low part per trillion) amounts of perfluorobutanoic acid (PFBA).
What Was 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 PFAS.
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 PFAS detected in that well and nearby wells. All homes where PFAS 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 PFAS plume are also sampled to monitor any changes in the size and concentration of the plume.
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 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.
Lake Elmo's Water Supply - March 2018
The municipal water in Lake Elmo is safe to drink and use for all household purposes. The Minnesota Department of Health (MDH) has been monitoring city water for many years and found low levels of PFOA in one well, slightly above MDH's Health Based Value (HBV). This well has been shut down and PFOA is no longer in the city water at any concentration.
PFOA first appeared at low levels (0.048 ppb) in one city well (well #1) in 2013. Concentrations increased slightly in 2014 to 0.086 ppb and have been on a decreasing trend ever since; decreasing to 0.023 ppb by 2016. In May 2017, the concentration in well #1 had fluctuated up slightly to 0.052 ppb. This is typical of groundwater contaminants – even if concentrations are trending downward, there is usually a bit of fluctuation. Although the PFOA concentrations are continuing to decrease, the average over the period from April 2017 – Feb 2018 was slightly above 0.035 ppb, so MDH issued an advisory to the city and the city shut off well #1. The concentrations of PFOA have not been high enough or present long enough to pose a potential health risk. Well #1 was shut off to eliminate PFOA from the city water.
According to the city, well #1 supplied water only to those residents on municipal services south of the railroad tracks and along Lake Elmo Ave. south to 5th St. Other areas of the city are served by the other wells that were not affected.
- City of Lake Elmo
- Public Health Assessment: Perfluorochemical Contamination in Lake Elmo and Oakdale, Washington County, Minnesota- 2008 (PDF)
- Water Treatment Using Carbon Filters: GAC Filter Information
- Special Well and Boring Construction Areas
- Review of Private Well Data: Former Washington County Sanitary Landfill - July 2009 (PDF)
The 3M - Oakdale Disposal Site (sometimes called the Oakdale or Granada Dump) is located along Old Hwy 5/County Road 14 in Oakdale, just west of Interstate 694, and is listed as a Superfund site on EPA's National Priority List. It consists of three old chemical waste dump sites (Abresch, Brockman, and Eberle sites) that were used during the late 1940s-1950s for waste burial, drum reclamation, and open burning of combustible materials. 3M has indicated that PFAS waste was disposed at this site. Ground and surface water near the area is contaminated with a wide variety of organic chemicals. Soil contamination also occurred at the site.
The Minnesota Pollution Control Agency (MPCA) first investigated the 3M - Oakdale Disposal Site in 1980. A variety of hazardous substances, particularly volatile organic compounds (VOCs), were found at the site. Some nearby shallow residential wells had VOCs at concentrations above levels of health concern in the past, but these homes are now on city water.
3M completed several remedial actions in the 1980's to address soil and groundwater VOC contamination: a large volume of waste material and contaminated soil was removed from the site; the site was covered with clean soil; monitoring wells were put in to sample the groundwater on a regular basis; and a groundwater pump-out system was constructed at the site in 1984-85 to intercept the pollutants in portions of the shallow aquifer. The pump-out system is still in operation today.
PFAS at the 3M-Oakdale Disposal Site
More recently, Perfluoroalkyl Substances (PFAS) have also been detected in the monitoring wells at the 3M - Oakdale Disposal Site. PFAS-containing wastes, disposed of in the 3M-Oakdale Disposal Site and the former Washington County Landfill, seeped into the groundwater. PFAS from both sites also entered Raleigh Creek, which flows from the Oakdale Disposal Site eastward into the city of Lake Elmo, where it discharges to Eagle Point Lake in the Lake Elmo Park Reserve. PFAS from both sites have created large groundwater plumes extending to the south-southwest of the disposal areas, while PFAS traveling in Raleigh Creek have also infiltrated to the groundwater, so that in Lake Elmo, the groundwater and some lakes are contaminated by PFAS from both sites.
PFAS have been detected in one private well in Oakdale (now sealed) and approximately 300 private wells in the southwest part of Lake Elmo. Low levels of PFAS from the Washington County Landfill have been detected in one of Lake Elmo’s municipal wells, but are below MDH drinking water criteria. PFAS primarily from the 3M-Oakdale Disposal Site have been detected in most of the Oakdale municipal wells, some of which exceed MDH drinking water criteria.
What Was Done
All homes where drinking water wells exceed MDH drinking water criteria are provided with granular activated carbon (GAC) filter systems, which the MPCA monitors and maintains, or were connected to city water. In 2006, 3M funded the construction of a GAC treatment plant to treat water from Oakdale's primary municipal water wells and also funded the installation of a new city well outside the area of PFAS contamination. More information about Oakdale city water can be found at: Oakdale Public Water Supply and Perfluorochemicals. 3M also funded the extension of city water to approximately 200 homes in Lake Elmo.
In 2008-2011, 3M completed additional cleanup actions at the site to further reduce both VOC and PFAS contamination. This included soil vapor extraction to reduce VOC concentrations prior to additional soil excavation. Contaminated soils were disposed of off-site at lined containment facilities. The groundwater pump-out system was expanded to increase the area of capture and a large GAC filter system was added to remove PFAS from the water before it is discharged to the sanitary sewer. More information about the cleanup actions can be found on the MPCA site.
- 3M Report - Locations of the 3 Dump Sites that Constitute the "Oakdale Dump", 2005 (PDF)
- MDH webpage - City of Oakdale Public Water Supply and Perfluorochemicals
- Public Health Assessment: Perfluorochemical Contamination in Lake Elmo and Oakdale, Washington County, Minnesota, August 2009 (PDF)
- Environmental Protection Agency:
EPA Superfund Program: Oakdale Dump, Oakdale, MN
- Oakdale Public Water Supply
Maps are developed based on sampling data available according to the date on the map.
MPCA has an interactive map which you can use to locate your address and determine if you are within an area of concern.
Maps Updated March 2018
- PFBA in the East Metro - 2018-2011 (PDF)
- PFOA in the East Metro - 2018-2016 (PDF)
- PFOA North of I-94 - 2018-2016 (PDF)
- PFOA South of I-94 - 2018-2016 (PDF)
- PFOS in East Metro -2018-2016 (PDF)
- PFOS North of I-94 - 2018-2016 (PDF)
- PFOS South of I-94 - 2018-2016 (PDF)
- Private Well Sampling Areas in the East Metro - 2018 (PDF)
- Priavte Well Advisory Locations - 2018 (PDF)
Aqueous Film Forming Foams (AFFF)
Statewide, MDH and MPCA have evaluated other places where PFAS may have been released to the environment, including: fire training facilities where special PFAS-bearing fire-fighting foams (also called AFFF) were reportedly used, chrome plating plants, waste water treatment plants, and landfills. Although PFAS have been detected at many of these locations, most do not pose a risk to public health.
Aqueous Film Forming Foams (AFFFs) are used by fire fighters to help extinguish fires that are difficult to fight, particularly fires that involve petroleum or other flammable liquids (also known as Class B fires). Not all firefighting foams are classified as AFFF. Some AFFF formulations contain a class of chemicals known as Perfluoroalkyl Substances (PFAS).
This is more likely to occur near places where PFAS-containing AFFF has been used repeatedly, such as a fire training areas, airports, refineries, and chemical plants. It is less likely to occur from the one-time use of AFFF to fight a fire, unless large volumes of AFFF are used. Although some portable fire extinguishers may use PFAS-containing AFFF, one time use of such a small amount would be unlikely to pose a hazard to groundwater.
In 2008, the MPCA conducted a survey of fire departments, airports, refineries, and other potential AFFF users around the state to identify locations where PFAS-containing AFFF has been repeatedly used for training or firefighting purposes. MDH and MPCA staff reviewed this information and identified a number of locations where nearby water supply wells were potentially at risk.
In 2009, MDH sampled municipal wells in 17 communities and 16 noncommunity public wells (those that serve businesses, schools, churches, etc.) near the identified AFFF sites.
Low levels of some PFAS were detected in 7 municipal systems. No PFAS were detected in the other municipal wells or in any of the noncommunity public wells tested. View the summary of the Class B Firefighting Foam- Municipal Well Investigative Sampling Results (PDF).
In 2008-2011, MPCA tested the soil, surface water, groundwater, and sediments at and near 13 AFFF sites around the state. They detected high levels of PFAS at some of the sites, but in most cases the contamination did not affect a large area or pose a risk to humans or the environment. For more information on these investigations view the survey and sampling activity report: PFC Containing Firefighting foams and their Use in Minnesota (PDF). Three sites – Duluth Air National Guard Base, Bemidji Airport, and Western Area Fire Training Academy (WAFTA) - were identified where PFAS had spread far enough that MDH and MPCA decided to test nearby residential wells. The MPCA is continuing to investigate these sites and evaluating what additional actions may be needed.
- Duluth Air National Guard
- Western Area Fire Training Academy (WAFTA)
- Pine Island