Calgary officials say they’re still trying to determine the cause of a pipe failure that allowed wastewater to leak into the Bow River across from the Bonnybrook Wastewater Treatment Plant on March 28.
Officials said the material would have “diluted quickly” and had minimal impacts downstream, but the amount of wastewater released is unknown.
Doug Morgan, Calgary’s general manager of operational services, told a press conference that the wastewater flow at the leak site on the east bank would have been about 1.3% of the total flow in the river.
Calgary officials first noticed an issue more than a week before the leak was discovered. They couldn’t figure out why wastewater levels flowing to the Bonnybrook Wastewater Treatment Plant (WWTP) were lower than normal and dropping each day. When no issues were found within the plant, crews started to look for external factors in the 5,000-kilometre wastewater system that could have caused the issue.
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After test results on the Bow River water showed elevated E. coli levels near the Bonnybrook WWTP, crews had identified an issue with a pipe on the east bank of the river by 2:30 p.m. on March 28. They closed the valve to the pipe and rerouted the wastewater to the two other functioning pipes so that service could continue.
Calgary officials said that upon discovering the leak, they immediately reached out to Alberta Health Services, Alberta Environment and Protected Areas, and communities downstream. Monitoring indicates the leak has been contained, but staff continue to test water quality and assess the situation.
While a precise figure around the wastewater leak was not announced, Calgary Mayor Jyoti Gondek confirmed to reporters that the leak was “fully contained.”
“The truth is that this is a legacy issue that has spanned decades,” Gondek told a press conference. “Maintenance and infrastructure investments have often been deferred, written off as too expensive, or deprioritized in favour of short-term goals. But neglecting critical infrastructure has serious consequences.”
Crews were focused on pumping sewage out of the pipe before any repairs.
Morgan said it’s not the industry standard to inspect these types of pipes, and that this pipe in particular had not been inspected for 15 years.
“Until we know how it failed, we can’t say that an inspection would have prevented the issue,” Morgan said. “This incident highlights the importance of having built-in system redundancies. Within hours of getting the test results, we shut down the impacted pipe,” he added.
The city confirmed Calgary’s drinking water hasn’t been impacted and said the risk to the public is low. Officials are currently conducting a full assessment of the incident.
