A year ago, dozens of St. Louis Park residents woke up to sludge spewing from basement drains and toilets as over a million gallons of water, dirt and sewage rushed into more than 50 homes, flooding basements with more than two feet of muck. Two weeks later, another water main break nearby flooded some of the same homes again.
The basements are dry and mostly repaired, but officials in St. Louis Park and other suburban cities are growing more concerned about their water mains and sewers coming of age all at once — and what it will cost to keep up with repairs. In Excelsior, residents are paying higher property taxes after a series of water main breaks in 2020. In Bloomington, they're seeing water and sewer rate hikes so the city can keep up with repairs.
"We may be the canary in the coal mine for first-tier suburban communities," St. Louis Park Mayor Jake Spano said.
The Twin Cities' inner-ring suburbs boomed in the years just after World War II, with many cities built in a single spurt of development. More than 60% of St. Louis Park's houses were built between the late 1940s and early 1950s, and nearly all the water and sewer infrastructure was in the ground by 1960.
The infrastructure worked well for decades. But as those water mains and sewer lines get older, cities are going to have to do more to monitor and maintain them — which will mean spending more.
"For a long time in newer communities, suburbs, the infrastructure was essentially brand new," said Scott Anderson, utilities superintendent in Bloomington. "A lot of that infrastructure is tending to age out all at once, or in big pieces."
Older, larger cities aren't immune. Duluth, which saw most of its water and sewer infrastructure installed in the 1930s and early 1940s as part of the Works Progress Administration, has been dealing with water main trouble in recent years.
The May 21, 2022, water main break in St. Louis Park was the result of soil around the cast-iron pipes corroding a series of holes in the main, which was installed under Minnetonka Boulevard in 1956. An investigation by an outside firm found water from the holes broke into a nearby sewer line, pushing 1.1 million gallons of muck into homes. Replacing the broken section of pipe put pressure on a nearby section of water main, which cracked in early June and sent more water rushing into basements.