The city of Cottage Grove broke ground late last month on a new $39 million water treatment plant billed as a long-term solution to PFAS-contaminated groundwater.

The granular-activated-carbon plant will draw water through a new well to replace two existing wells contaminated with the toxic manufacturing chemicals. The city will pay for the plant with some of the $91 million it received from the $850 million settlement the state of Minnesota reached with 3M in 2018.

The company pioneered the use of per- and polyfluoroalkyl substances, a group of chemicals known as PFAS, in the 1950s. They were used in a wide variety of products from firefighting foam to nonstick pans. The so-called "forever chemicals" do not break down in the environment and have leached into waters around the world. Maplewood-based 3M still faces numerous lawsuits and earlier this year announced a $10 billion-plus national settlement of PFAS suits involving drinking water.

The new Cottage Grove plant, at Ideal Avenue S. and 110th Street S., will treat all water needed for homes south of Hwy. 61. It should be functional by 2025, according to Cottage Grove Public Works Director Ryan Burfeind. A second, larger plant will eventually be built behind the Central Fire Station on 80th Street to supply water for homes north of the highway.

The city has built five temporary plants since May of 2017 — including two this year — to treat its water for PFAS contamination. All five of those plants will eventually be closed as the new plants come online. In the past six years, the city has also added new water mains and connected 183 homes to city water.