Early results indicate there was no single factor that led to last June’s Bearspaw water feeder main rupture, according to a preliminary review.

The City of Calgary said late Friday that they would be presenting a public update of the preliminary report, overseen by Associated Engineering and Pure Technologies, on Nov. 26.

In June, a massive breach of the Bearspaw water feeder main sent Calgary into a series of water restrictions as they dealt with the initial break and then the subsequent repairs. At that time, the City of Calgary said they would conduct their own forensic review of the incident, along with having an independent third-party also do a review.

Calgary Mayor Jyoti Gondek was recently critical of administration for not having any new updates to provide to the public during a recent city council meeting. At that time, Michael Thompson, General Manager of Infrastructure Services said they’d do a better job of providing updated information in real time.  

The early findings show that there were possibly several factors, including microcracking of the protective mortar outer layer of pipe, high chloride levels in the soil and wire that snapped due to corrosion and hydrogen embrittlement, the City of Calgary said.

“The Bearspaw South Feeder Main is a critical piece of infrastructure, and it is responding well to the rehabilitation work that was completed between June and November, and is now stabilized,” said Thompson, in a Friday afternoon news release.

 “Through our acoustic monitoring, we have recorded only two wire snaps on the feeder main between October and November. Throughout July and August, there were 23 wire snaps.”

Deeper dive into the pipe health needed, says Ward 1 councillor

Ward 1 Coun. Sonya Sharp, who, along with fellow area Coun. Terry Wong (Ward 7) presented a notice of motion looking for a full review of infrastructure in the Bowness and Montgomery area, said this information was a good start, but a deeper look is still needed.

“We’re getting a little bit closer, yes, I think that they’re being pressured to deliver answers, because we are getting a lot of questions, especially Councillor Wong and I in representing Montgomery and Bowness,” she said.

“What I’ll say about what the findings are, is clearly what we had in the ground was not built last.”

Sharp said the City of Calgary had indicated that there was an inspection of the line roughly a decade ago.

“Don’t tell me 10 years ago you didn’t find any level of chloride to think that you might have needed to inspect it,” she said.

“There’s a lot of corrosion that happens in 10 years for a pipe of that size to go through catastrophic failure.”

According to information provided by the City of Calgary, the preliminary review of the design and operation of the feeder main showed that both were consistent with the guidelines of the time and operated well within the design parameters of the pipeline.

The City said the final pipeline investigation report would be presented to the Infrastructure and Planning Committee on Dec. 11.

Meanwhile, construction work is ongoing for two additional segments for the Bearspaw water feeder main. There are two sites, one at Parkdale Blvd NW between 26 and 27 Street and another at the Memorial Drive westbound off-ramp to northbound Crowchild Trail NW.

Both projects are nearing completion, the City of Calgary said.