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CALGARY, ALTA. — A public meeting on the preliminary findings of an investigation into the massive feeder main break that occurred in June, leading to months of water restrictions and other onerous measures, is set to be released Nov. 26.

City administration will be providing an update to the public at the regular council meeting.

The purpose of the pipe investigation, overseen by Associated Engineering and Pure Technologies, is to understand the factors that led to the deterioration of the feeder main and its failure on June 5, explains a release.

The preliminary findings indicate several different factors, including:

• microcracking of the protective mortar outer layer of the pipe;
• high chloride levels in soil at various locations; and
• wires that snapped due to corrosion and hydrogen embrittlement.

The report indicates there was not one specific factor that led to the failure of the feeder main.

“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,” says Michael Thompson, general manager of infrastructure services, in a statement. “Through our acoustic monitoring, we have recorded only two wire snaps on the feeder main between October and November. Throughout July and August, there were 23 wire snaps.”

The preliminary review also confirmed the original pipe design was consistent with the proper guidelines of the time and operations of the pipeline were well within the design parameters.

A final pipe investigation report will be released Dec. 11.

When it comes to the long-term rehabilitation of the feeder main, the city is reviewing options, with contingency planning by developing an enhanced emergency response plan, equipping the feeder main with acoustic fibre optic monitoring and maintaining a critical parts inventory.

Construction work on the two additional segments of the Bearspaw South Feeder Main, one along Parkdale Blvd N.W. between 26 St and 27 St N.W. and the other at Memorial Dr. westbound off-ramp that connects to Crowchild Tr. Northbound, are nearing completion, the release reads.