Surprising reason why Portland’s water mains break

Portland Water Bureau replaces up to 12 miles of pipe each year

Workers repair a broken water main pipe at NW 23rd Place, which closed the road between Burnside and Everett, Oct. 20, 2014 (KOIN 6 News)
Workers repair a broken water main pipe at NW 23rd Place, which closed the road between Burnside and Everett, Oct. 20, 2014 (KOIN 6 News)

PORTLAND, Ore. (KOIN) — Nothing can stop an old pipe from breaking when conditions come together. But the Portland Water Bureau has an ongoing effort to try and replace the most vulnerable pipes before they break.

A water main break happened at SE 69th Avenue and Duke Street Sunday, January 22, 2017. (Portland Water Bureau)
A water main break happened at SE 69th Avenue and Duke Street Sunday, January 22, 2017. (Portland Water Bureau)

The latest casualty of Portland’s unusually cold winter: a 16-inch cast iron water main, laid in the ground near SE 69th and Duke in 1930. It’s the 82nd water main break in Portland in a little over 3 weeks.

“To get 82 in less than one month is a phenomenal rate of breakage and it’s really correlated to the cold weather temperatures that we’ve had here in the last month or so,” said the bureau’s Ty Kovatch.

A water main broke on SW 2nd Avenue, December 16 2016. (KOIN)
A water main broke on SW 2nd Avenue, December 16 2016. (KOIN)

It’s not that pipes are freezing. It’s the cold water entering the city’s water supply network from Bull Run Reservoir.

Kovatch, who is the bureau’s Maintenance & Construction director, said as the water from Bull Run drops to 39 degrees pipes start breaking.

To try and keep ahead of the problem, the city monitors and tracks breakage rates and uses that information to proactively replace bigger sections of water main if they’ve had frequent isolated breaks on them in the past.

“In theory,” Kovatch said, “we’re eliminating problems that we might have with those that we believe are most likely to fail.”

There is more than 2200 miles of pipe in the Portland Water Bureau’s system. On average, between 5 and 12 miles of water main are replace a year.

Portland’s is a relatively young system compared with older cities in colder climates. But as the city learned the first 3 weeks of one of the coldest months in recent memory, cold weather causes water mains to break.

Replacement pipes for underground water delivery in Portland, January 23, 2017 (KOIN)
Replacement pipes for underground water delivery in Portland, January 23, 2017 (KOIN)