State offers options to keep St. Paul suburban water free of 3M chemicals

A long-awaited solution for east Twin Cities metro residents whose drinking water was contaminated with 3M-made chemicals is a step closer to reality.

On Thursday, the Minnesota Pollution Control Agency and the Department of Natural Resources released three options, which all continue to rely on groundwater as the main source of drinking water for the region — and also aim to make sure that water is safe and plentiful in the future.

The two agencies are recommending a plan that would build new city wells or treatment plants for some of the 14 affected cities; connect some homes with private wells to municipal water systems, and provide others with in-home filters to remove the chemicals from their water.

The $700 million cost — the same for all three options — will be covered by the settlement from Minnesota’s landmark 2018 legal settlement with 3M over the impacts of the chemicals, known as PFAS. 

PFAS, or per- and poly-fluoroalkyl substances, are human-made chemicals known for their ability to repel water and tendency not to break down. They have been used in a variety of consumer products, including Teflon cookware, Scotchgard stain repellent and food wrappers.

Beginning in the 1940s, 3M produced two PFAS compounds at its Cottage Grove plant. It disposed of waste containing the chemicals at sites in the east metro, where they contaminated the groundwater over about 150 square miles, affecting the drinking water of about 174,000 people.

3M phased out production of the two PFAS by 2002. But cities such as Cottage Grove, Woodbury, Lake Elmo and Oakdale have been dealing with the impacts on their drinking water supplies.

Some cities have had to stop using wells or install costly new treatment systems because of PFAS levels that exceed state health guidance values.

Studies have linked long-term exposure to certain levels of PFAS in drinking water to health problems, including liver and thyroid disease, developmental issues and certain types of cancer. 

All three options proposed by the two Minnesota state agencies would use a lower threshold of PFAS in residents’ drinking water than what’s currently used to decide who qualifies for treatment.

The lower levels will allow communities to better handle changes in the future — such as new research on the health effects of PFAS that results in lower health limits, said Kirk Koudelka, an assistant MPCA commissioner.

“We know there are uncertain conditions in the future,” he said. “We’ve seen it in the past. PFAS is the most studied contaminant right now, and we will continue to learn more.”

Koudelka said the agencies’ top option also sets aside the largest amount of money — $38 million — for future uncertainties, such as the contamination plume moving to new areas.

The 3M settlement will cover construction costs under all three scenarios, but it is a finite amount, Koudelka said. How long the settlement money will continue to pay for ongoing costs to operate and maintain the treatment systems varies with each option, he said.

The agencies’ preferred plan would cover the operation and maintenance costs for about 40 years for public water systems, and about 100 years for private wells.

One of the other options would treat drinking water with a lower level of PFAS, but it would cover maintenance costs for a shorter period — about 35 years.

The third option would connect the cities of Oakdale and Lake Elmo to St. Paul’s regional water system and would cover about 21 years of operating costs.

Koudelka said all three options also target money toward making sure drinking water is protected and available in the future. The preferred option includes about $70 million for drinking water protection and $60 million for sustainability efforts to reuse or conserve water.

“If we’re going to rely on groundwater in this area for a growing area, we want to make sure there’s enough there into the future,” he said.

One proposal that was debated earlier was to switch some cities’ drinking water from groundwater to surface water sources, such as the Mississippi or St. Croix rivers. Koudelka said that option was ruled out due to higher costs and because the cities didn’t support it.

A public comment period on the three options is open through Oct. 26. Two virtual meetings are planned for Sept. 22 and 23 to get public input. A final decision will be made early next year.