The City of Calgary is designing a project to twin a section of the Bearspaw feeder main after its rupture forced the city into months of water restrictions last summer.
Although details were limited during a presentation from city administration to councillors Wednesday, construction could begin later this year.
The proposal would see twinning of up to five kilometres of the Bearspaw feeder main, along sections made of pre-stressed concrete cylindrical pipe (PCCP), the same that caused concerns around the pipe’s integrity following its critical rupture last June.
That situation forced the city into water restrictions that lasted months, as more than 20 repairs were completed on the pipe, which carries around 60 per cent of the city’s drinking water.
Steve Wyton, the city’s manager for asset management said there remain sections of the feeder main that will need to be replaced or repaired over the coming years, and a twinned line would help with redundancy.
“The twinning option would alleviate that concern over the long-term and allow us to operate the pipe safely,” Wyton told reporters.
“We still do have to decide over the longer term what would be the use of the existing feeder main and time will tell as we go through the detailed design process.”
Further details around costs, timelines and project delivery are expected to go to city council later this year with an implementation plan.
The city is considering microtunnelling to twin the line in an effort to minimize service disruptions and reduce impacts to residents and businesses in the Bowness and Montgomery neighbourhoods.
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“We don’t have to close roads, we don’t have to disturb private property except for a shaft where you drop the tunnel boring machine,” Ward 7 Coun. Terry Wong told reporters.
Prior to choosing microtunnelling, the City of Calgary was looking into installing a liner inside the existing feeder main to help reinforce the pipe, but Wyton said it would’ve required longer period of service disruptions and more significant construction impacts over a number of years.
Less disruptions would be welcomed for Shawn Kearns, who operates Greenbriar Market + Refillery in Montgomery, which saw business take a hit during the lengthy repairs on the feeder main last summer.
“We saw a slowdown of traffic and customers coming through the door and our customers were telling us they weren’t coming because of the craziness over here,” Kearns told Global News.
Ward 1 Coun. Sonya Sharp, who represents areas that were impacted by the feeder main rupture, said she hopes to have communication with the public on a plan.
“They went through a lot last summer,” Sharp said. “Now that we have some time to work with them and be proactive, maybe it’ll alleviate some stress that they will feel.”
According to city officials’ presentation to committee, the move would help create more redundancy as part of a series of projects aimed at increasing capacity in the overall water system.
Those projects include upgrades to the Glenmore Water Treatment Plant, an expansion of the Bearspaw Water Treatment Plant, as well as new feeder mains servicing new communities in north and south Calgary.
Sharp believes city administration will use more than $1 billion in approved borrowing included in the 2025 budget to help pay for these projects in the coming years.
“Everything is catching up to us. For the last decade it’s been deferred, deferred, deferred, and not been a top priority,” Sharp said. “Council and future council’s need to pay attention to what infrastructure means to our city.”
According to a nearly 600-page report into the feeder main break, overseen by Associated Engineering, there were several factors which are believed to have led to the incident.
Those factors include microcracking, or previous damage to the outer layer of the pipe, which allowed soil contact with the pipe’s prestress wires, causing stress corrosion cracking and hydrogen embrittlement.
The report noted soil conditions near several sections of the feeder main contained high levels of chlorides, likely from salt used in de-icing materials on city streets.
While officials note their timeline of starting construction at the end of this year is “aggressive,” some councillors believe it will come with challenges.
“When you realize all the projects they’ve got going, even if you run them concurrently, project management is a significant task,” Wong said. “If they can get it done, great.”
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