A contaminated site in Edina and St. Louis Park has been placed on a priorities list by the Environmental Protection Agency, a move that will provide financing to investigate the pollution's source and permanently clean it up through the federal Superfund program.

"We're very supportive," said St. Louis Park Mayor Jake Spano. "This is something we've been tracking for a long time."

The Minnesota Pollution Control Agency (MPCA) in August 2019 asked the EPA to place the site of a groundwater plume on the National Priorities List because it is contaminated by several volatile organic compounds known to cause cancer.

The boundaries of the area, which is referred to as the Hwy. 100 and County Road 3 Groundwater Plume site, are W. 33rd Street to the north, S. France Avenue to the east, W. 58th Street to the south and Blake Road to the west.

Placement on the priorities list means a remedial investigation will be conducted to determine the nature and extent of the pollution, said Stephanie Ross, the site's remedial project manager with the EPA.

To do that, EPA officials will analyze previously collected data and complete additional field work, which could include steps like drilling boreholes to examine the soil or installing wells to test groundwater. Through that process, the EPA and MPCA will determine the best type of cleanup.

"I'm excited to start working with the MPCA on it," Ross said. "I think it's a really interesting puzzle."

Cleanup methods for groundwater vary depending on the type of contaminant, how concentrated it is and whether it's moving, Ross said. Possible strategies include pumping water out to treat it, building a barrier underground to keep it from moving or injecting materials to break down contaminants where they are.

The contamination's source might also be excavated and removed, said Patrick Hamblin, who oversees the EPA's priorities list in the region.

The MPCA already has done a lot of work on the site, Hamblin said.

In 2004, the MPCA began to look for the source of vinyl chloride contamination that was detected in several Edina wells. Over several years, the source was linked to an area near Walker and Lake streets in St. Louis Park. In 2007, MPCA samples showed high levels of chlorinated solvents in the groundwater, which could cause vapor intrusion, meaning the chemicals could move into the air.

Both Edina and St. Louis Park have also worked with the MPCA and EPA to address health concerns related to drinking water and vapor intrusion.

Those efforts include shutting down water treatment plant no. 4 in late 2016 to complete a "massive upgrade," Spano said. The improvements allow the plant to treat all of the identified contaminants and keep them within allowable levels.

There have been 48 Minnesota sites placed on the National Priorities List, an EPA spokesman said. There are 26 sites listed and 22 have been deleted after cleanup goals have been achieved.

The last Minnesota site listed on the National Priorities List was in Spring Park in 2018.

Erin Adler • 612-673-1781