The federal government moved closer to making a groundwater plume of contamination in St. Louis Park and Edina a national priority for the Superfund program.
After a request from the Minnesota Pollution Control Agency, the U.S. Environmental Protection Agency announced that it would publish a rule in the Federal Register Nov. 7 that would propose to add the Minnesota site to its National Priorities List.
The program considers in-depth information about each proposed site that is scored using the federal hazard ranking system. The system is a screening system that uses information from initial, limited investigations “to assess the relative potential of sites to pose a threat to human health or the environment,” according to the agency.
The proposed site relates to a groundwater plume along Highway 100 and County Road 3, also known as Excelsior Boulevard, according to federal documents. The groundwater plume is contaminated with volatile organic compounds, a group of chemicals used in solvents, paints and dry-cleaning fluids that can cause an increase in health risks, according to the EPA.
“The extent of the groundwater plume has not been determined but appears to have contaminated municipal and monitoring wells in the cities of St. Louis Park and Edina,” the document states.
Environmental investigative work began when a specific chemical, vinyl chloride, was found in an Edina municipal well, according to the document. The MPCA conducted several investigations between 2004 and 2013. The investigations “found a large chlorinated VOC plume contaminating multiple aquifers,” the document states. Along with vinyl chloride, the volatile organic chemicals found at the site include trichloroethene (TCE), tetrachloroethene and cis-dicholoroethylene (cis-DCE).
Of potential impacts, the document says, “The drinking water of the approximately 48,000 people served by the St. Louis Park municipal well field and the 50,000 people served by the Edina well field may be threatened by the contamination. Prior to treatment, several of the drinking water wells were found to contain VOC concentrations exceeding federal and/or state regulatory standards. However, all water is treated prior to distribution to customers.”
The MPCA helped improve water treatment for the cities. In Edina, the state agency helped the city construct “a centralized water-treatment facility that processes all the water produced from contaminated Edina wells,” according to the EPA. In St. Louis Park, the state agency helped design the construction of an upgraded water treatment system at Water Treatment Plant No. 4, which the city had shut down due to contaminants in the water.
“As a result, drinking water provided by both the cities of Edina and St. Louis Park currently are in compliance with all (Maximum Contaminant Levels) as established in the Safe Drinking Water Act,” the EPA document says.
It also notes that the EPA’s Emergency Response program installed vapor mitigation systems at about 40 residential and commercial properties found to be at-risk for vapor intrusion in 2008 and 2009.
Despite the past responses, the federal document says, “The state of Minnesota referred the site to the EPA due to the potential impacts, size, scope and complexity of the site and the need for further investigation and clean-up. Other federal and state cleanup programs were evaluated but are not viable at this time.”
Another document used for the federal government’s complex scoring system shows a map of potential sources of groundwater contamination at the site. Most of the locations are near Highway 7, such as a dry cleaner business, a former print shop, and a former metal fabricator in the Historic Walker Lake district. Across the highway, the map of potential sources shows a computer components facility, heat transfer facility, dry cleaning fluid distributor and other businesses in the industrial area west of the former Sam’s Club. One dry cleaning business in Edina is also listed.
“Several potential sources exist, but MPCA has been unable to identify a source(s) to which the VOC contamination in the deeper aquifers could be definitively attributed,” the EPA summary states.
If the EPA ultimately adds the groundwater plume site to the list, the Superfund program could fund further investigation and cleanup activities.
In an Oct. 30 statement, St. Louis Park officials said they are pleased with the federal process thus far. The city notified residents in September of the state’s request for the EPA to add the site to the list.
“The city is in full support of this action to ensure the ongoing health and safety of residents and that those who caused the contamination are held responsible,” the statement reads.
The city council conducted a closed executive session in July to “discuss potential litigation and legal strategy” relating to the plume of contaminants,” according to the agenda for the meeting.
Jacque Smith, communications and marketing manager for the city, said at the time that a target of such a lawsuit was not known.
Although the EPA’s map lists potential sources of contamination from a relatively wide area, the Oct. 30 city statement pinpointed the source to “an area near Walker and Lake streets in St. Louis Park.”
The city statement says, “While an exact source hasn’t been identified, it’s important to note that the businesses associated with the chemical release no longer operate in these areas. Contamination in the groundwater is from previous uses.”
After the EPA lists the site in the Federal Register, a 60-day public comment period will begin. The site will be added to the National Priorities List “if it continues to meet the listing requirements after the public comment period closes and the agency has responded to any comments,” according to the city statement.
For more details, visit epa.gov/superfund/current-npl-updates-new-proposed-npl-sites-and-new-npl-sites and stlouispark.org/groundwater-plume.