The public will hear for the first time what investigators believe led to the rupture of a critical line in Calgary’s water system in June at a city council meeting later this month.
In a news release sent late Friday afternoon, the City of Calgary confirmed preliminary findings from an investigation into the Bearspaw feeder main pipe will be presented to city council on Nov. 26.
The investigation was overseen by Associated Engineering and Pure Technologies after sending an inspection device through the line, and was meant to “understand the factors that led to the deterioration of the feeder main and its failure on June 5, 2024,” the city said in release.
According to the city, the preliminary findings indicate that several factors may have contributed to the pipe failure including microcracking of the “protective mortar” outer layer of the pipe, chloride levels in the soil at various locations along the line, as well as wires snapping due to “corrosion and hydrogen embrittlement.”
The wires are tightly coiled around the pipe and encased in concrete, with the pre-stressed wires meant to help with structural reinforcement.
“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,” the city’s Infrastructure Services general manager Michael Thompson said in a statement.
“Through our acoustic monitoring, we have recorded only two wire snaps on the feeder main between October and November.”
There were 23 wire snaps throughout July and August, according to Thompson.
The rupture of the line on June 5 plunged the city into Stage 4 outdoor watering restrictions for months, as repairs were needed along several segments of the pipe following the initial break.
According to the city, preliminary review found the original design of the pipe was “consistent with the proper guidelines of the time and operations of the pipeline were well within the design parameters of the pipe.”
Repairs are still ongoing and expected to be complete later this month on two additional sites along the line that don’t require city-wide water restrictions because of where they’re located.
The first is along Parkdale Boulevard N.W. between 26 Street and 27 Street N.W., and the other is near the Memorial Drive westbound off-ramp connecting to Crowchild Trail.
“The city is currently reviewing options for long term rehabilitation of the feeder main and continues with contingency planning by developing an enhanced emergency response plan, equipping the feeder main with Acoustic Fibre Optic (AFO) monitoring and maintaining a critical parts inventory,” the city said in its release.
The finalized pipe investigation will be presented at the Infrastructure and Planning Committee on Dec. 11.
The City of Calgary is also conducting a forensic review into the feeder main break, while an independent third party is also set to launch a review of its own into the incident.
No more water restrictions in Calgary
