The June flood event along mountain creeks in Canmore has resulted in questions concerning several future development areas located in alluvial fans.
While there are still no answers from the province about how already built homes along Cougar Creek will be addressed after significant erosion of yards last month, Town of Canmore officials say future development potential along Stoneworks, Stewart, Three Sisters and Pigeon creeks will have to be revisited.
Gary Buxton, general manager of municipal infrastructure, said the long-term implications of flooding in alluvial fans that are fed by those creeks are not yet known, but it would be incredibly naďve not to look at those lands differently now.
“Stoneworks, Stewart, Pigeon and Three Sisters all have development potential of some sort along their courses. Previously, we have never understood that those creeks could behave like that; now that we understand that they can behave quite dangerously, I think it is incumbent to look at that in the planning realm,” Buxton said. “The Municipal Development Plan has to look at known hazards in the community and I think when we revisit the MDP that section might be considerably more developed than it has been previously.”
In the past, only the Bow River was recognized as a serious flood risk in the community. But with the one in 100 storm event that saw Cougar Creek in particular cause extensive erosion to its banks all the way up to the foundations of some homes and seriously affect the railway tracks and Trans-Canada and 1A highways, the community’s flood risk has changed.
At the first meeting of council’s flood recovery committee last Thursday (July 11), Mayor John Borrowman and Councillors Sean Krausert and Hans Helder were briefed on how the municipality will move forward to understand that new risk and put together a plan to mitigate for it.
Administration has put a call out for consultants to establish an expert review panel in order to look at the 2013 flood event and then prepare a hazard and risk assessment. In particular, the experts are hoping to provide a better understanding about flood risks from mountain-based creeks and the alluvial fans into which they drain.
“The initial group of people will look at what happened and what sort of likely event and flows and volumes and materials are we likely going to have to deal with and that then gives you the parameters you have to design around,” Buxton said. “The design has to be a separate phase of the plan – it is knowing what you are dealing with first in terms of hazard and risk assessment and then you move towards thinking about a design.”
Meanwhile, the Town of Canmore has backfilled Cougar Creek as a temporary measure and is working on re-establishing Benchlands Trail to Eagle Terrace, which is estimated to take 10 days to two weeks. Homes that still have a backyard and that allow municipal access are being stabilized with material as a temporary measure.
What happens to those homes affected and who is in charge is still undetermined and will involve the provincial disaster recovery task force.
MLA Ron Casey said the Province understands people feel an urgency for details at this point for rebuilding, “but right now, there may not be all the answers everyone needs to make the right choices.”
He said the task force intends to work with individual communities to find the right solutions. Canmore and Lac Des Arcs, for example, experienced major erosion events along the waterways, which is different from communities like Bragg Creek and High River, so recovery plans for each will be different.
“The one thing they are making very clear is that this is a community by community program, so in other words it isn’t one size fits all. So what occurs in Canmore may not be the same solution as High River or Bragg Creek or somewhere else,” Casey said, adding the information coming out of Canmore’s expert panel will likely be included in that process. “So as a mitigation plan comes forward to re-establish those channels and work with those channels, we can incorporate some of the recommendations from this expert panel, which hopefully will give them some hints to lessen the impact of these events.”
The former mayor of Canmore noted that even with mitigation measures, the risk cannot be completely erased, especially when dealing with an event of the magnitude that June’s flood was.
However, he did point to Canmore’s dike system along the Bow River, which was put in after a flood in 1974 and has prevented overland flooding in the downtown core and South Canmore ever since.
“The truth is, if it is done right and with the right amount of information then they do work and that makes those areas safe to live in because of that,” Casey said. “That doesn’t mean there isn’t a chance or eliminate all risk, but it makes the likelihood of an occurance that much less.”
Manager of engineering Andy Esarte said he estimates up to $2 million has been spent on the emergency response and repair work, all of which he expects to be recovered through the disaster recovery program.
Looking forward, Esarte said while it is still to be determined whose jurisdiction the creek is for building mitigations and who pays, the Town wants to be the driving force in understanding what happened and “not the province taking care of this for us.”
“At this point, I do not anticipate we are going to have (permanent) mitigation on these creeks for 2014, but we want to have it all started by next June and we are likely looking at temporary mitigations.”
He said administration would like to get working on hazard and risk assessment as soon as possible to have a better understanding of what temporary mitigations can be established before next June.
