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The Minnesota Pollution Control Agency is recommending that a portion of an Andover neighborhood where contaminated well water was discovered last year be connected to the city's municipal water system.

The recommendation outlined in a virtual meeting Thursday comes after the agency found high levels of the cancer-causing chemical 1,4-dioxane in private wells in the Red Oaks neighborhood.

Original sampling last summer showed about 40 wells primarily in an area east of NW. Quinn Street and north of 138th Avenue with concentrations of dioxane that exceed the Minnesota Department of Health's values for safe drinking water, including one well testing at 2,200 times the value. Anything above 1 microgram per liter creates health concerns, according to a fact sheet produced by the Health Department.

A recently completed resampling of the wells showed no changes to the original results, the MPCA said.

The chemical 1,4-dioxane was used as a stabilizer for the chlorinated solvent that was often used for industrial purposes. Groundwater contaminated with the chemical is largely caused by the historical use and disposal of chlorinated solvents, the MPCA said.

Long-term exposure can present serious potential health risks. The primary way people are exposed is by drinking contaminated drinking water, the agency said.

"Connecting impacted residents to Andover's municipal drinking water system will eliminate the pathway to exposure and ensure a suitable long-term drinking water source," the agency said.

Gov. Tim Walz has asked that $12 million be included in a bonding bill to bring city water to homes in the affected area and seal impacted wells. There would be no cost to homeowners to hook into the city water system under the plan.

"We are working with the MPCA to bring water to the area," said Andover City Administrator Jim Dickinson. "We are trying to get this thing solved."

The neighborhood is on the city sewer system, but is not on the water system because homes were built before it was available in the area, Dickinson said.

Homes to the west of Quinn Street and north of 139th Avenue did not have chemical levels that exceeded Health Department guidelines. Wells at those properties will be tested once or twice this year. Homes in what is defined as the "Monitoring Area" will not be hooked up to city water.

The MPCA is continuing to try to identify the source of the contamination, spokesman Matt Croaston said.

Red Oaks is near the Waste Disposal Engineering Landfill. In 2019, Gov. Tim Walz declared the defunct landfill, now managed by the MPCA, one of the most toxic sites in the state. More than 6,600 barrels of hazardous waste were disposed of there in the 1970s. The 2019 bonding bill included $10 million to begin cleaning it up.

The MPCA said it will continue to monitor wells at the closed landfill as part of the ongoing groundwater investigation and try to determine if the landfill is contributing to the contamination. The agency is also studying other possible sources given that higher levels of contamination were found at properties farther away from the landfill than those that border it, which is unusual.

"Therefore, additional investigation is needed to establish the source of the Red Oaks' contamination as well as the nature and extent of the contamination," the agency wrote in a January report.