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Concrete mats going into Cougar Creek

Cougar Creek is getting a complete makeover. The mountain stream, which flooded to unprecedented levels in June, is slated for flood mitigation work that will change the way the channel looks permanently.

Cougar Creek is getting a complete makeover.

The mountain stream, which flooded to unprecedented levels in June, is slated for flood mitigation work that will change the way the channel looks permanently.

While in the past large rock, or rip rap, has been used to armour the channel, plans for the future are to install articulated concrete mats.

“Within the channel itself, we had large rip rap armouring and that was undermined and outflanked by the (June) event, so we are looking at different approaches to use,” said Andy Esarte, manager of engineering for the Town of Canmore last week. “We looked at gabion baskets and we also looked at articulated concrete mats.

“The concrete mats themselves have some mass and they have some strength to resist the impact of boulders and then they are tied together with cables so there is a continuous blanket of concrete.”

The mats are made of concrete blocks which are 70 pounds per square foot, and are tied together by cables into mats. In total, 48,000 square feet of mats are needed to line the channel, which are being fabricated locally.

“It isn’t beautiful,” Esarte said of how the mats will look, “but they can be covered with grass over time, so they can get back to a more natural state.”

The mats will begin upstream of the furthest house along Cougar Creek and reach the Trans-Canada Highway. The channel of the creek will also be widened, which is the work currently underway, and the bottom of it lined with large rock. Rock will also be used to protect culverts under Elk Run Blvd. and Highway 1A.

The pedestrian bridge over the creek will also be removed for the channel to be widened and Esarte said as part of the long-term solution for the creek, the Town will look at re-instating that bridge.

The concrete mats are meant to withstand the force of debris in the stream, but there are also efforts to stop debris upstream of the community as well.

“Debris was obviously a big problem plugging the culverts, debris also changes the properties of the flow so it makes it more capable of eroding the banks and it destroys the armouring,” Esarte said. “We want to capture a certain amount of that sediment and we are doing that upstream at a bedrock-confined section of the channel that is 40 metres wide.”

The plan, he said, it to install a debris net, which is a short-term solution. It is expected the net will contain 20,000 cubic metres of debris in a storm event. This past June, Cougar Creek saw 90,000 cubic metres of debris come down the channel.

The net will let water and small debris through, and is expected to be designed so both wildlife and hikers can get through.

“Downstream, the channel is actually quite small so once you get the sediment out and it starts behaving like a hydraulic creek again that has taken care of the majority of your problems,” Esarte said.

The work Canmore is doing in its creek is in partnership with the provincial government, which is funding part of the $14 million project.

Associate Minister of Recovery and Reconstruction Kyle Fawcett was on hand Friday (Nov. 15) for an update to the work. He said the province is assessing recovery work on a project-by-project basis for each community.

“What you are going to see over the next month are some specific announcements on some of these types of projects moving forward and that we are committed to those and will be supporting municipalities in that way,” he said.

Fawcett said the government is impressed with the work Canmore has undertaken during and after the flood.

“I said this right from the beginning, we have been very impressed with the leadership shown by the Town of Canmore,” he said. “The situation that happened here during the flood was unfortunate and frankly unique compared to some of the other areas.

“The Town has really embraced that uniqueness and dealing with the very unique problems along Cougar Creek and we are willing to work with them as a partner with that.”


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