$48M Canmore debris dam set to break ground in 2019
A $48-million debris dam in Canmore, meant to prevent the kind of damage seen in the devastating 2013 southern Alberta floods, is set to break ground next year.
The structure is set to be built along Cougar Creek, said Andy Esarte, manager of engineering with the Town of Canmore, adding that the structure is intended to prevent major debris floods in the future.
“It depends a little bit on how the permitting process goes, but we’ll be pushing hard to be in the ground by the middle of next year,” said Esarte.
The area where the 30-metretall structure is set to be built was once ravaged by the 2013 floods, as debris-ridden water rushed through the creek, ruining adjacent homes and shutting down the Trans-Canada Highway.
It caused extensive damage to the Cougar Creek area, decimating municipal infrastructure by washing out roads and damaging significant utilities, as well as flooding houses in the area.
It is anticipated the new structure will be able to stop as much as 650,000 cubic metres of water and sediment.
By comparison, there were roughly 90,000 cubic metres of debris in the 2013 flood, which led to the evacuation of 1,200 residents from 300 homes near the creek.
During heavy rainfalls, the new structure is designed to direct water along with large wood and rock debris into an inundation area.
The water will then be released in a controlled manner back to Cougar Creek downstream of the structure.
A detailed risk assessment “showed we had a high risk of loss of life. We had a significant economic risk,” Esarte said.
“That left us looking at different structural mitigation approaches in addition to updating emergency response plans and looking at how we develop.
Esarte said work had been done on the area in 2012 before the town experienced the onein-100-year flood.
“It had (caused) a bunch of bank erosion and we were worried at the time we might even lose a pedestrian bridge,” he said.
“After that event, we thought we had the big one because based on all the studies that had been done before, that was a flow we could expect once in a hundred years.”
Crews worked to strengthen the eroded banks after the 2013 flood.
“Within 24 hours, all the protection we put in place and all the understanding we thought we had disappeared,” said Esarte. The project to launch the new structure was born of the idea to understand how to mitigate future debris flows.
Last week, the town received approval from the Natural Resources Conservation Board, a critical step in continuing the process of building the structure.