Variety of factors caused feeder main pipe to fail: City of Calgary [Video]

The city released preliminary findings of an investigation into the failure of the Bearspaw South feeder main late Friday afternoon suggesting that there were a number of factors behind its failure.

The purpose of investigation, which was overseen by Associated Engineering and Pure Technologies, was to better understand what led to the deteroriation of the pipe until it failed on June 5, 2024.

Investigators isolated three possible factors in its Friday statement:

• Microcracking of the protective mortar outer layer of the pipe;
• High chloride levels in soil at various locations; and
• Wires which snapped due to corrosion and hydrogen embrittlement.

They concluded that there was no single factor that led to the failure of the feeder main in June.

“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,” said City of Calgary infrastructure services general manager Michael Thompson.

“Through our acoustic monitoring, we have recorded only two wire snaps on the feeder main between October …