Thursday marks one year since the catastrophic rupture of Calgary’s Bearspaw South Feeder Main - an event that sparked a citywide state of emergency, weeks of water restrictions and a long-term rethinking of Calgary’s water infrastructure.
The six-and-a-half-foot concrete pipe, located under 16 Avenue N.W., burst suddenly on June 5, 2024.
Water gushed across the road, flooding nearby sports fields and prompting an immediate emergency response.
It was just the beginning of what city officials have described as one of the most significant infrastructure failures in recent memory.
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In the months following, the City of Calgary carried out 29 separate repairs along the feeder main, with the final repairs completed by November 2024.
The system has since stabilized and is operating within acceptable structural limits, according to city engineers.
An investigation into the failure found several contributing factors:
- microcracking in the pipe’s protective mortar layer, allowing soil to reach and corrode the prestress wires;
- corrosion and embrittlement of those wires, exacerbated by chloride penetration; and
- aggressive soil conditions with high chloride levels, made worse by road salting.
While the internal review by APEGA (Association of Professional Engineers and Geoscientists of Alberta) is complete, an additional independent review by a panel of industry professionals is still pending.
“There has been a review done by APEGA that verified we met all engineering standards and that our response was to the standard they expected,” said Mayor Jyoti Gondek.
“We have an independent review that is still to come that is a panel of professionals in industry, so we continue to investigate what happened there. We have also invested a greater budget into the monitoring the maintenance and the technology that is required to make sure our water system is in good shape.”
City hall is now focused on preventing similar situations from happening in the future.
A major initiative currently in the planning stages is the twinning of the concrete portion of the Bearspaw South Feeder Main.
“Creating those backup plans or that redundancy is something that administration has taken very seriously,” noted Gondek. “We are putting in more feeder mains to ensure that we can meet the needs of Calgarians and the people that are moving here. We are looking at twinning to make sure that redundancy exists, and we rely on administration to come to us with timely information.”
The city said the twinning project may use micro tunneling technology to minimize surface disruption. Construction could begin by the end of 2025, but the design and budget for the project have yet to be finalized.
