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Groundwater Plume

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1. Is Edina’s drinking water safe?

YES! Edina’s drinking water is safe and meets or exceeds all federal and state standards. Part of the reason for that is Edina treats its water supply to remove contamination. Treatment can be costly but is vital to ensure the safety and quality of drinking water.

2. Who sets the standard for Edina’s drinking water?

Drinking water standards are set by the U.S. Environmental Protection Agency and regulated through the Safe Drinking Water Act. Here, standards are enforced by the Minnesota Department of Health (MDH) and Minnesota Pollution Control Agency.

The City of Edina works with the MDH to test drinking water for more than 100 contaminants. It is not unusual to detect contaminants in small amounts. No water supply is ever completely free of contaminants. Drinking water standards protect people from substances that may be harmful to their health.

3. How often is Edina’s water tested?

The Minnesota Department of Health tests for volatile organic compounds at Water Treatment Plant 6 and Wells 2, 4, 7, 13 and 15 wells quarterly. Testing for other things such as fluoride and chlorine is done by the Public Works staff daily.

4. What’s the history of groundwater contamination in Edina?

In the early 2000s, Well 7, a well in Sherwood Park drawing from the Prairie du Chien/Jordan Aquifer, tested above the Maximum Contaminant Level set by the U.S. Environmental Protection Agency for vinyl chloride, a colorless organic gas with a sweet odor. At that time, Well No. 7 was a seasonal well and was operated only in the summer.

Well 7 was shut down in early October 2003 and was not turned on again until after a high-capacity treatment plant was built at the Danen’s Building at 5120 Brookside Ave. in 2012. The plant is equipped with an aeration system specially designed to filter out volatile organic compounds. The treatment plant is Water Treatment Facility No. 6. It treats four of the City’s 18 wells, including Well 7.

5. What is vinyl chloride?

Vinyl chloride is an organic colorless gas at normal temperatures and is a liquid at temperatures at or below 56 degrees Fahrenheit. It can be smelled at concentrations of 3,000 parts per million (ppm) in air and tasted at approximately 3.4 ppm in water. Vinyl chloride is a man-made substance, or the result of a breakdown of a man-made substance.

Vinyl chloride is used in the manufacture of numerous products in building and construction, automotive industry, electrical wire insulation and cables, piping, industrial and household equipment and medical supplies and is depended upon heavily by the rubber, paper and glass industries.

6. Where does vinyl chloride come from?

The typical source of vinyl chloride, according to the Environmental Protection Agency (EPA), is discharge from plastics factories. Vinyl chloride can also be a byproduct of degradation of other complex chlorinated compounds such as cleaning agents and solvents.

7. What are the health risks of exposure to vinyl chloride?

The effects of drinking high levels of vinyl chloride are unknown. Potential health risks are damage to the nervous system and liver.

No symptoms of sickness or disease have been reported to the City since the problem was discovered.

8. How much did it cost to build Water Treatment Plant 6?

Total cost of the Water Treatment Facility was more than $8 million. The Minnesota Pollution Control Agency paid for the design of the plant, which totaled more than $250,000.

The approximate cost to operate Water Treatment Facility No. 6 is about $440,000 annually.

9. Is water from private wells safe?

Water from private wells should be tested by their owners. Private wells used for irrigation are much shallower than the Jordan aquifer where the contamination exists.

10. What is the source of contamination?

The source of the contamination has not yet been determined.

Typically, Minnesota Pollution Control Agency (MPCA) staff try to find the sources of contaminants. MPCA staff collected and analyzed samples from monitoring wells, industrial wells, irrigation wells and other municipal wells located in the western Twin Cities metro area. The results showed a “volatile organic compound trail” that allowed the MPCA to trace the contamination back 2.3 miles, to a contamination site in St. Louis Park.

The MPCA has narrowed the list of contaminators to five properties. However, MPCA has exhausted funding in identifying the exact source of contamination.

11. Where is the plume?

The site is generally bounded by West 33^rd Street to the north, South France Avenue to the east, West 58^th street to the south and Blake Road to the west. Multiple land uses are present in the area, including residential, recreational, commercial, industrial and vacant properties. There is not a hard boundary; the plume shifts slightly in the Prairie du Chien/Jordan Aquifer.

12. Is the contamination just vinyl chloride?

No. The deep groundwater plume, dubbed the Highway 100 and County Road 3 Groundwater Plume Site, contamination consists of volatile organic compounds (VOCs), including tetrachloroethylene (PCE), trichloroethylene (TCE), cis dichloroethylene (DCE) and vinyl chloride (VC), collectively known as chlorinated VOCs. PCE is an industrial solvent used to degrease metals. Under the right conditions, PCE can break down in the environment to form TCE, DCE and VC.

13. What is TCE?

According to the U.S. Environmental Protection Agency (EPA), trichloroethylene (TCE), perchloroethylene (PCE) and trichloroethane (TCA) are the most frequently detected volatile organic chemicals (VOCs) in ground water in the United States. Due to its unique properties and solvent effects, TCE has been widely used as an ingredient in industrial cleaning solutions and as a “universal” degreasing agent.

14. What are the health concerns of TCE in drinking water?

In 2013, the Minnesota Department of Health (MDH) conducted a toxicological review of TCE in drinking water. MDH concluded that the main health concerns from exposure to TCE at the lowest exposures are immune system effects such as immunosuppression or autoimmune disease, including hypersensitivity; an increased chance of cancer from long-term exposure; and heart defects in the developing fetus if the pregnant mother is exposed in the first trimester. Other health effects related to TCE are observed only at higher exposures.

15. What amount of TCE in drinking water is safe?

In 2013, MDH developed a Health-Based Value, or guideline, of 0.4 micrograms of TCE per liter. This level of TCE is safe for all people exposed to TCE in drinking water at any time during their life, including pregnant women and their fetuses, infants, children and other sensitive people, including those with impaired immunity.

A level of 2 micrograms per liter of TCE in drinking water protects all people who are exposed for an entire lifetime from cancer. The increased risk for cancer is estimated to be 1 additional cancer case in 100,000 people, which is considered a negligible cancer risk. The level is also safe for healthy adults who are only exposed to TCE after age 18, and protects pregnant women and their developing fetuses from heart defects.

16. How big is the plume of contamination?

The plume is 324 to 545 feet below ground. About 1,940 properties in Edina are above the Highway 100 and County Road 3 Groundwater Plume. They have an estimated market value of $1.454 billion.

17. How was the size of the deep plume determined?

Existing wells that are open to the deep aquifer and used to define the plume include:

• monitoring wells installed as part of an investigation at Reilly Tar & Chemical Corp., a different contaminated site in St. Louis Park
• industrial production wells
• golf course irrigation wells
• municipal wells  
  

With sample data from these wells, the Minnesota Pollution Control Agency was able to determine the extent and magnitude of the plume in this drinking water aquifer. The plume is defined by wells where chlorinated volatile organic compound contamination was detected above the Minnesota Department of Health’s drinking water standards.

18. What’s the difference between the deep groundwater plume and the shallow groundwater plume?

The area in St. Louis Park closest to the suspected source of contamination has contamination above the bedrock, too. This perchloroethylene/trichloroethylene (PCE/TCE) soil vapor plume resulted in soil and vapor issues in certain properties. Those issues were mitigated by the Minnesota Pollution Control Agency (MPCA) in 2008. In 2015, the MPCA verified the soil vapor intrusion mitigation systems installed in those residential properties were still operating. No vapor intrusion problems were identified.

The shallow plume is only in St. Louis Park and is not migrating.

19. Is there any chance this contamination could extend into another of Edina’s wells?

The spread is unlikely. The strategy of pumping the northernmost wells (Wells 2, 7 and 15) is to create a hydraulic barrier to halt the spread of the plume has proven to be effective. No wells to the south have had any contamination. Based on the sampling data, both the shallow and deep groundwater plumes are not spreading.

20. Will my property be tested?

Local drinking water is certified safe. There are no soil or vapor issues in Edina. Local soil tests are not warranted.

21. Is it safe to garden or harvest my fruits and vegetables?

Water coming out of Water Treatment Plant No. 6 is safe. Yards and gardens irrigated from private wells are safe, too, as the irrigation process aerates the water. Also, water evaporates.

22. What’s next in dealing with the solvent plume?

The cities of Edina and St. Louis Park continue to treat drinking water to ensure it is safe.

The Minnesota Pollution Control Agency has applied to the U.S. Environmental Protection Agency (EPA) for the solvent plume site to be placed on the National Priorities List (NPL). Minnesota has requested and is pursuing the NPL listing with the EPA for a number of reasons.  This groundwater contamination plume is at least 324 feet deep and covers areas within both St. Louis Park and Edina. The State has dedicated a large amount of funding and staffing to define the area to date; however, there is still much work to be done to investigate and eventually clean up the area of contamination. 

The amount of funding required to identify the source area, pursue potentially responsible parties and implement a cleanup plan far surpasses the amount of funding the State’s Superfund program receives each year. Funding support from the federal government will assist with additional investigation activities and bring in additional technical expertise and specialized legal counsel to effectively address the complexities of the site. If a potentially responsible party or parties can be identified, cost recovery efforts can be pursued.

23. Are there other National Priorities List sites in Minnesota or across the nation that have groundwater plumes as the basis for listing?

Yes. Many of the more than 1,300 sites that have been listed on the National Priorities List include a groundwater contamination plume. Two examples in Minnesota are the New Brighton/Arden Hills Superfund Site (also known as the Twin Cities Army Ammunition Plant or TCAAP Site) and the Baytown Groundwater Contamination site.

The TCAAP Site plume extends under several cities, including New Brighton, Arden Hills, Columbia Heights, St. Anthony and Minneapolis.

The Baytown Groundwater Contamination plume is approximately five miles long, covers about seven square miles, and extends from the eastern portion of the City of Lake Elmo through Baytown Township, West Lakeland Township and the City of Bayport to the St. Croix River.

24. What effect does the Highway 100 and County Road 3 Groundwater Plume Site have on property values?

The National Priorities List (NPL) listing is for the deep groundwater plume. The deep groundwater plume is at a depth of 324-545 feet. Due to its depth, the deep contamination does not affect individual properties.

The major concern of the deep groundwater plume is its impact to the cities’ municipal wells. To mitigate this impact, both the cities of St. Louis Park and Edina have installed treatment systems to ensure their drinking water meets the requirements of the federal Safe Drinking Water Act and the State’s drinking water guidance values. Once the site is placed on the NPL, the U.S. Environmental Protection Agency (EPA) and the Minnesota Pollution Control Agency will continue working to identify sources of the deep groundwater contamination plume.

If you have additional questions regarding property value, the EPA suggests that concerned property owners consult a professional property appraiser who can give a more accurate response to property value questions and concerns.

25. What is the difference between the Reilly Tar & Chemical site and the Highway 100 and County Road 3 Groundwater Plume Site?

These are two different chemical releases that were caused by different sources.

The Reilly Tar & Chemical Corp. contamination is mainly creosote, which contains polycyclic aromatic hydrocarbons (PAHs) that were at one time used in wood-treating operations. The Reilly site has previously been listed on the federal National Priorities List, and the U.S. Environmental Protection Agency (EPA) and Minnesota Pollution Control Agency have been overseeing cleanup there since the late 1970s.

Contamination at the Reilly site is the result of:

• wastes discharged directly to a ditch that flowed into a wetland on the southern side of the property
• contaminated soil from leaky pipes and various processes that spilled during operations
• creosote and waste materials that likely seeped down several wells historically located on the property
  

For more information, visit the EPA’s Reilly Tar webpage.

26. Are you really sure my drinking water is safe?

YES! Under the Safe Drinking Water Act (SDWA), the U.S. Environmental Protection Agency (EPA) sets standards for drinking water quality and the Minnesota Department of Health (MDH) enforces these drinking water standards for public water supplies. The treatment systems for both cities are designed to treat for VOC contamination associated with the Highway 100 and County Road 3 Groundwater Plume Site.

In addition to the federal SDWA, MDH has Health Risk Limits (HRLs) and Health Based Values (HBVs) that are used as guidance values for public drinking water supplies. HRLs and HBVs may be more stringent than federal SDWA levels.

The Minnesota Pollution Control Agency has worked with both cities to design treatment plants to clean the drinking water to meet these more stringent values.

27. What’s next?

The U.S. Environmental Protection Agency in September 2020added the Highway 100 and County Road 3 Groundwater Plume to the Superfund National Priorities List. The listing ensures the cities of Edina and St. Louis Park have a permanent solution to groundwater contamination. 

The amount of funding required to help identify the source area, pursue potentially responsible parties and implement a cleanup plan far surpasses the amount of funding the State’s Superfund program receives each year. Funding support from the federal government will assist with additional investigation activities and bring in additional technical expertise and specialized legal counsel to effectively address the complexities of the site. If a potentially responsible party or parties can be identified, cost recovery efforts can be pursued.