City knows where its feeder main failed—and how it might prevent a repeat

Flaws in feeder main's outer layer caused failure The city says the major failure of Calgary's largest water feeder main was due to corrosion and cracks in the pipe's outer layer.

The major failure of Calgary's largest water feeder main in the summer was due to corrosion and cracks in the pipe's outer layer.

But officials say the issue is now fixed and they have a plan to protect the water system moving forward.

Nearly 30 repairs were completed along the water line.

The break, which happened in June, impacted all of Calgary for weeks.

A combination of microcracking on the outer layer, broken wires due to corrosion and high chloride levels impacting the concrete are all factors.

The city found 23 wire snaps in the months after the initial break.

But since repairs and upgrades, just two wire snaps have been found in the fall along a seven-kilometre stretch.

Officials also say most of the water pipes in the city are not made with the same materials as the one that broke.

The city is also compiling more data to be better prepared in the future.

"The team that would normally compile the information was busy with the response," said Francois Bouchart, the city's director of capital priorities.

"So, it took a little bit longer to simply compile the information that we had."

Some of the data predicts more repairs may be needed in the next five years.

The city is now looking at two options for how to prevent this in the future, including lining existing pipes on the inside or tunneling to install a new parallel pipe.