Utility workers in the Twin Cities are putting in a lot of cold hours fixing water lines frozen or cracked by the frigid weather that has gripped the area since early December.

More than 40 days of subzero lows have taken a toll on water systems, freezing pipes in Eagan, Bloomington, Richfield, New Hope, Plymouth and Anoka, among other cities. Public works crews have found frost piercing deep enough to freeze inch-thick service lines under streets and, in some cases, to plague much wider pipes 7 or 8 feet beneath road surfaces.

On a sunny but bitter day last week, lead worker Fawn Kinsman endured minus-8 windchills as her crew spent about three hours patching a broken 8-inch-wide iron water main under East River Road in Coon Rapids.

“It’s been a very unusual year” for frozen water lines, Kinsman said.

In St. Louis Park, Utility Superintendent Jay Hall said the city has seen more service line freeze-ups than in typical winters. Hall is a leader with the Suburban Utility Superintendents Association and says its website has been humming with members seeking and offering advice on how to handle frozen lines that connect to city water mains.

In Minneapolis, many homeowners have had frozen water pipes, but the city hasn’t experienced an unusual number of frozen municipal pipes. That may be because city mains are large and buried 8 feet deep, said city spokesman Casper Hill.

In other places, such as Bloomington, “This has been an extremely tough year,” said Utility Superintendent Bob Cockriel. He said last week that Bloomington crews had fixed 10 broken mains and dozens of frozen service lines and found frost reaching down 7 feet.

“That is really, really deep,” Cockriel said, especially when most water pipes are 7 or 8 feet underground. He noted that frozen pipes are often found beneath bare streets, not under snow-covered lawns, which insulate the ground.

“Traffic pounds the frost down to the pipes … and impacts water service lines,” Cockriel said. He said the cold also descends through catch basins and shallow stormwater pipes that carry frigid air below ground.

Cockriel said the last time Bloomington had such frequent problems was the winter of 1977-78, when about 160 service lines froze and some water mains froze solid.

Another problem

Many mains in New Hope and parts of neighboring Plymouth suffer another cold-weather hazard: clay in the soil. Last week a broken 12-inch main closed Armstrong High School in Plymouth.

Clay absorbs moisture and freezes solid around pipes. So when frost pushes a pipe against the clay, “it makes the pipe snap,” said Bernie Weber, New Hope utilities supervisor. He said clay is acidic, which corrodes and causes pipe bolts to fail.

Weber said more than 20 water mains, from 6 to 12 inches in diameter, have cracked and been repaired since Nov. 1, more than in most years.

Coon Rapids crews have handled more than 30 frozen, inch-thick copper service lines so far, after none in the past two winters, said utilities operation supervisor Rick Bednar. He noted the city has advised all homeowners, especially those whose lines have frozen, to consider letting one faucet “trickle” around the clock to avoid freeze-ups for the rest of winter.

Other cities, including Fridley and St. Louis Park, suggest that homeowners who have had frozen pipes take similar action. Fridley has warned residents that discolored tap water may be the first indicator of service line freeze-ups, which may be prevented by letting a faucet trickle, said Public Works Director Jim Kosluchar.

“It’s scary,” Bednar said. He said crews have worked almost nonstop in recent weeks. He noted he’s seen frozen ground 6 to 8 feet deep that has cracked about seven water mains so far, several more than in most winters.

“I expect more when the frost comes out [moving earth around pipes] after being down so deep,” he added. He said the city often learns about frozen lines from homeowners who call “when they wake up in the mornings and find out they don’t have water.”