Series of mishaps leads to expensive overage costs for Canmore’s wastewater repairs

The Canmore wastewater treatment plant's aeration system was comprised at the bottom of the filters as the result of a design flaw. This led to the plant losing between 30-50% of the aeration system.

A process disruption, emergency repairs and replacements, as well as scheduled rehab work, led the Alberta town of Canmore’s public works department to request an additional $1.36 million from its Town Council last month.

The events at the town’s wastewater treatment facility date back to 2016 and primarily hinge on a design flaw from the 1996 construction of not only Canmore’s facility, but other similar facilities built across North America and Europe at the time. The treatment facility uses 10 filters that remove ammonia before the wastewater is returned back to the Bow river. Bacteria within the filters remove the ammonia.

“That bacteria was severely diminished sometime in late December. At the time we didn’t know why. But it was to the point that the plant’s ability to remove ammonia was diminished, and we did not meet our approval limit,” EPCOR site manager Dennis Letourneau told Canmore Town Council at its May 1 meeting.

The high ammonia levels resulted in seven violations of the Town of Canmore’s approvals with Alberta Environment to run the wastewater treatment plant.

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The aeration system at the bottom of the filters had become compromised as the result of a design flaw, leading to the plant losing between 30-50% of the aeration system that supplies oxygen to the bacteria so that it can live. To fix the problem, technicians needed to remove about 1,000 m3 of a rock-like substance called biolyte.

“There’s about a million dollars of biolyte in that plant right now. It’s pricey stuff,” said Letourneau. “It’s fragile. You can’t just simply grab it with a front-end loader and swing it out. You’ve got to put it into a slurry and use a special induction system that we manufactured based on a similar system in Châteauguay, Quebec, and carefully, gently remove all of that biolyte out of the filter and store it” he added.

Getting to the bottom of the ammonia issue took investigators about 10 months and $1.1 million.

Public works also replaced the plant’s flow transmitter, added level transmitters and ammonia analyzers.

“We instrumented the plant enough so that we could know what was going on,” said Letourneau.

Typically, Canmore has about three distribution main breaks during a winter season, but a particularly severe winter over 2016-17 led to seven main breaks for Canmore.

“It was the worst ground frost event that anyone can remember,” said Letourneau, noting that the main breaks ended up costing the Town about $400,000.

Emergency repairs involving concrete issues with specific wastewater plant channels led to other expenses for the Town over the winter season, added Letourneau. Parts of the concrete actually broke off, he said.

Another wastewater plant repair involved a local citizen losing control of their truck and striking a plant beam. The beam warped, leading to a $20,000 repair job, Letourneau told council.


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