July 16th, 2024

Freeze-thaw cycles contribute to frequency of water main breaks

By Alejandra Pulido-Guzman - Lethbridge Herald on January 22, 2022.

Herald photo by Al Beeber A ruptured watermain sprays under a section of broken asphalt that created a sinkhole under 6 Ave. South last week that cost two commuters damage to their vehicles.

LETHBRIDGE HERALDapulido@lethbridgeherald.com

Did you know that southern Alberta has the most freeze-thaw cycles in Canada?
The temperature fluctuations that we have been experiencing in the last couple of weeks, thanks in part to chinook winds and climate change can make those cycles somewhat unpredictable.
These freeze-thaw cycles can cause damage to infrastructure that is buried under the roads across the city, especially outdated cast iron pipes.
“What happens when you get these alternating freeze-thaw cycles is the frost goes deeper and deeper into the ground. And then you’re in a real situation or in a pickle, when it gets down to the depth of the water main,” said Doug May, Civil Engineering Technology instructor for Lethbridge College.
May said that the extremely cold temperatures we experienced in the last couple of weeks are an anomaly, and that is why some of the freeze went so much deeper than before.
He said that once it gets to the water main depth, which is approximately six feet or 2.2 metres deep, it can freeze the water within the main or it can affect the joints and other things around it.
“In Alberta the further you go north, the deeper it (water main) has to go. In Fort McMurray their water mains are buried deeper than ours,” said May.
In Lethbridge they are buried at a depth that is not significantly affected by frost this early in the year, according to Jeff Koshuta, water and wastewater operations manager for the City of Lethbridge.
He told the media on a video conference on Friday, that one of the main reasons for waterman breaks is the fact that some of the older parts of the city have cast iron pipes under the roads.
“I can generally say a lot of cast iron was installed in the ’40s, ’50s and ’60s, and in the ’70s that’s when pipes switched over to different materials, and then of course in the later ’80s primarily PVC has been use,” said Koshuta.
He said in 2021 the city experienced 36 water main breaks and that was very close to what was experienced in 2020, as the city had 34 water main brakes.
He added that this month the city had four water main breaks already, but the 10 year average for January water main breaks is five.
“We are very confident that once our program continues to target the unpredictable cast iron pipe, we will continue to trend downwards in water main breaks,” said Koshuta.

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