To improve reliability after last year’s major rupture, planning officials with the City of Calgary are considering microtunnelling as a way to twin the pre-stressed concrete cylindrical pipe portions of the Bearspaw South Feeder Main.
In a presentation to the Infrastructure and Planning Committee on February 12, planning and engineering staff said that although repairs to the Bearspaw feeder main were undertaken in 2024, a growing number of pipe segments exhibit deterioration and will continue to worsen over the next 5 to 30 years.
“Microtunnelling is preferred as it best minimizes impact to adjacent citizens and businesses and service impacts to Calgarians,” states a report to the planning committee, which says five kilometres of the pipe could be twinned to bolster asset redundancy.
Microtunnelling is a trenchless construction method that uses a small tunnel boring machine to create underground utility tunnels. Calgary city staff has used the technique for several sanitary trunk projects.
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If confirmed, the new feeder main would move water to south Calgary from the Bearspaw Water Treatment Plant and could be completed by 2031.
The existing 50-year-old feeder main ruptured on June 5, 2024, launching a summer of intense water restrictions for residents and businesses.
“This feeder main is and will continue to be an important part of Calgary’s water infrastructure and as such will continue to be monitored and operated in a manner that reduces the risk of failure,” the planning report continued.
Design of the Bearspaw South Feeder Main Reliability project will begin in Q1 2025 and construction could begin by the end of the year.
Project cost estimates are not currently available.
