Review finds no evidence of 'unprofessional conduct' in Calgary water main break
City's professional standards not a factor in 2024 rupture, says independent engineering report
As the one-year anniversary of last June's catastrophic water main break approaches, an independent review of the incident suggests that there was no wrongdoing by the City of Calgary's engineering or geoscience services.
The findings of a new report by the Association of Professional Engineers and Geoscientists of Alberta (APEGA) suggest that the pre-stressed concrete cylinder pipe (PCCP) failure experienced by the Bearspaw south feeder main is consistent with incidents across North America.
"PCCP manufacturing standards were relaxed from the late 1960s to the early 1970s by the American Water Works Association, resulting in a high rate of premature failures, and standards have since been strengthened," reads a release by APEGA.
The report found "no indications of unskilled practice or unprofessional conduct."
Had such evidence been found, APEGA would have launched a formal investigation.
Calgary Mayor Jyoti Gondek told CBC News that she's pleased with the findings of the independent review.
"I think that's the kind of reassurance that Calgarians are seeking, that this incident was managed in a professional manner," she said.
The Bearspaw south feeder main, Calgary's largest water feeder main and the pipe that transfers the majority of the city's treated water, ruptured on June 5, 2024, flooding a street with clean water.
Calgarians were asked to severely limit their water use as repairs got underway.
The city found numerous sections of pipe needed repairs, extending water restrictions into late September. At the time, Calgarians were prohibited from watering their gardens or lawns and were asked to keep limiting their indoor water use.
Since then, the water main has undergone significant repairs, while the incident prompted the City of Calgary to add water distribution infrastructure failure to its list of high-risk emergency scenarios.
The independent report's findings are consistent with the results of a review commissioned by the city in 2024.
Last year's forensic investigation, led by Associated Engineering, cited microcracking along the protective mortar outer layer of the pipe, high chloride levels in the soil at various locations, and snapped wires following corrosion and hydrogen embrittlement as factors that contributed to the failure of the feeder main, though no singular factor could be identified as the primary cause of the rupture.
Rupture was 'hard to predict'
Kerry Black, a civil engineering professor at the University of Calgary, said it's important for people to understand that the factors behind the rupture "are hard to predict," even by experts.
"They really did have a robust maintenance and prevention plan in place at the time of the rupture," she said. "Certainly we've seen other municipalities looking to the City of Calgary as a model, as an example of how you can do monitoring and prevention well, but that even when you do, things can go wrong."
The city is responsible for 16,000 kilometres of waste, storm and drinking water pipes, according to its own figures.
"There's a reality that monitoring and maintaining all of those kilometres of pipes is difficult," said Black.
While she believes Calgary has "a good plan in place," she said the city could do a better job of communicating its water infrastructure work, and the costs associated with that, to Calgarians.
"I know it's something that nobody really wants to hear about, but there's a reality: infrastructure costs money," she said.
"For me, [it's] that long-term planning of how are we getting everyday Calgarians to understand how costly it is to provide the infrastructure that we all rely on so much, and are we willing to help shepherd a path forward to acknowledging that?"
Gondek said that she and the city's infrastructure services general manager Michael Thompson will present "a detailed summary" next week, highlighting what's been done by the city since last year's incident.
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With files from Rick Donkers and The Canadian Press