After many years of investigation, the Minnesota Pollution Control Agency (MPCA) and the US Environmental Protection Agency (EPA) support the delisting of the Fridley Commons Park Well Field Superfund Site from the National Priorities List (NPL). 

The Fridley Commons Park Well Field site is an active well field with 8 municipal wells and the City of Fridley’s water treatment plant. Water from the wells is blended and treated onsite before it is distributed to the community.

The main contaminant at the site is trichloroethylene (TCE), which has the following risk-based values:

• Maximum Contaminant Level (MCL) established in 1987 by the EPA: 5 micrograms per liter (μg/L) (equal to parts per billion)
  • MCLs are the highest level of a contaminant allowed for public water supplies
• Health Risk Limit (HRL) established in 1994 by the Minnesota Department of Health (MDH): 30 μg/L
  • HRLs are the concentrations of a groundwater contaminant that can be consumed with little to no risk to health
• Revised HRL in 2007: 5 μg/L
• Revised HRL om 2015: 0.4 μg/L

The City of Fridley began sampling its wells for volatile organic compounds (VOCs) in 1980, and TCE was detected in 2 wells in 1983. However, TCE was not detected in the blended water distributed from the water treatment plant at that time. Subsequent testing revealed that a total of 4 wells were impacted by low levels of TCE. The City of Fridley managed the risk of exposure to contaminated water via a variety of methods including shutting off the well with the highest concentrations from 1989 to 2004, reducing water production from affected wells when demand allowed, and mixing water from impacted wells with water from non-impacted wells. It was ensured that any TCE concentrations in the finished water were below the MCL and HRL and therefore human exposure to TCE from the city’s water system has been below risk-based standards or non-existent.

Despite additional investigations from 2002-2005, the source of the contamination was not identified. In regard to other contaminants, no PFASs (per- and polyfluoroalkyl substances) were detected in any of the wells or water treatment plant. 1,4-dioxane has been detected in 4 wells, however concentrations have been well below the HRL and many have been near detection limits.

Site history:

• February 1991 – site placed on Comprehensive Environmental Response Compensation and Liability Information System (CERCLIS) inventory of potential hazardous waste sites
• June 1992 – site added to Minnesota’s Permanent List of Priorities (PLP), which is also known as the state Superfund list
• February 1999 – site listed on National Priorities List (NPL), which is also known as the federal Superfund list
• December 2003 – Feasibility Study completed and evaluated several remedial alternatives for the site
• 2005 – No Action Record of Decision (ROD) was proposed in July and signed in September
  • Additional monitoring of the 4 impacted wells has continued to monitor for TCE, as required by the ROD. Concentrations have been either undetectable or below the MCL and HRL and no breakdown products of TCE were being detected
• April 2010 – site removed from state Superfund list by MPCA

Since contamination at the site is limited to TCE and 1,4-dioxane in the groundwater, exposure to contamination is limited, the water supply is regulated by MDH under the Safe Drinking Water Act (the City of Fridley provides enhanced monitoring and collects samples at least 2x/year), emerging contaminants are either not detected or are in concentrations substantially below the MCLs and HRLs, and TCE in the site wells has been below the MCL and HRL since 2004, the MPCA and the EPA support the delisting of the site from the National Priorities List (federal Superfund list).

This information was summarized from the MPCA document here. See the full document for more information.