Flood Mitigation Measures Take Shape in Bragg Creek

by Ann Sullivan

The Elbow River and its banks have undergone millennia of change, shaped and sculpted by geological forces and the water’s flow. More recently, the flood of 2013 dramatically changed the river’s path through Bragg Creek. Now the area is being reshaped once again, this time by flood mitigation measures that include berms and retaining walls along a four-kilometre stretch of the river in Bragg Creek.

While some local residents welcome the new structures and the added protection they may bring, not everyone is happy to see the current work being done. The term “ecological grief” describes how some people feel about the loss of their connection to the Elbow and the possible harm to local species, from trout to deer to trees. 

Sept2020 Flood mitigation Bragg CreekIn late 2015, the provincial government and Rocky View County held a joint open house to introduce a proposed project that would protect Bragg Creek from the effects of a 1:100-year flood, that is, a flood that has a 1 percent chance of occurring each year. Much of the Hamlet of Bragg Creek is situated inside the floodplain of the Elbow River and has flooded regularly over the years. During the most recent major event in 2013, water flow was estimated at more than 1,100 cubic metres per second (m3/s), well above the largest previously recorded flood peak of 377 m3/s in 1995.

The proposed mitigation design, initially created by Amec Foster Wheeler (now owned by Wood Environment and Infrastructure Solutions, or Wood), is made up of four segments that cover 3,922 metres of riverbank area in the hamlet. The east Bragg Creek barrier, currently under construction north and south of the Balsam Avenue bridge, is the longest at 2,422 m. The two west Bragg Creek barriers, to be built on Bracken Road and private lands north of the bridge, are 590 m and 330 m long respectively. The west barrier near Yoho Tinda is 580 m long. These barriers are made up of three primary designs: earthfill dikes on the riverbank, concrete retaining walls adjacent to the river and landscape dikes set back from the floodway.

Mark Kamachi, Rocky View Division 1 councillor and a resident of Bragg Creek, said that when locals first learned of the proposed project, many were opposed to the scale of it and the changes it would bring to the community. “Any change in our neck of the woods always seems to come with negativity,” Kamachi said in an email, “and this was no different at first.”

Sept2020 Flood mitigation Bragg Creek riprap

When construction started on the east Bragg Creek barrier in June 2020, some residents were appalled by what they saw. “It was expected (finally),” Kamachi said, “but still a shock to the eyes as it was such a contrast to what we’ve been used to looking at.” Houses were moved or torn down and trees were bulldozed and left in piles on the banks of the river. Two months later, yellow construction fencing stretches along the riverbank as the structures take shape, and heavy trucks hauling dirt and rock are a common sight. The berms are being built and barriers are going up from just north of Bragg Creek Provincial Park to the properties north of the bridge on Balsam Avenue. 

Kamachi says, based on comments he receives, that most people are “very favourable” to the flood mitigation work. “I don’t understand how one can see a downside when it’s to protect this part of the community,” he said, adding that flood protection will be a boon to local businesses and tourism. “Folks who are against this project, or against any change, seem to be the most vocal. That’s human nature.”

Dave Klepacki, a long-time resident of Bragg Creek, geophysicist and co-founder of Experience Journeys, is not in favour of the project. He describes the work as a “necessary evil” to protect the area, but he would have preferred flood mitigation in the form of an instream reservoir built at McLean Creek. The McLean Creek proposal, which the Government of Alberta dropped in favour of the Springbank Off-stream Reservoir (SR1), would have been a much better option for flood mitigation, Klepacki said, and in addition would have provided “drought mitigation, [a] wildfire suppression facility, and recreational focus for increasing public presence in Kananaskis.”

Klepacki has two main concerns about the construction in Bragg Creek: groundwater flooding and the negative psychological impact of the structures that are “removing the River as part of the identity of Bragg Creek.”

Berms are being constructed on the river-connected aquifer, which means that while they may contain overland flooding, Klepacki said, water could seep under them and cause groundwater flooding. This happened along the Elbow River in Redwood Meadows and parts of Calgary in 2013. “If the berms elevate the river height,” Klepacki said in an email, “it only contributes to the gravitational head for this siphon effect.” In other words, water buildup along the bermed banks could increase the pressure that pushes groundwater out into the floodplain, increasing the risk for groundwater to rise into basements.

“Ponding” on the land side of the berms could also be a problem if the Elbow River breaches the new berms. Klepacki noted that when ponding occurred in High River in 2013, it took about a month for the water to drain away. He said that it would likely take a 1:200-year flood event to breach the structures in Bragg Creek.

Rafeal Odie, Rocky View County’s project manager, noted in an email that groundwater movement in Bragg Creek will be the same as in pre-construction conditions. “The flood barrier structures are designed to manage overland flow,” Odie said, “and will not affect groundwater movement.” As for any concern about groundwater seepage, Odie said that the hamlet is located in a floodplain consisting mostly of river gravel, and that seepage will occur “as in pre construction conditions.”

In 2013, most flood damage occurred because of overland flow. Sept2020 Flood mitigation Bragg Creek aerial

As for stormwater collecting on the residential side of the berm, Odie said overland drainage from properties adjacent to flood barrier structures will flow to a swale at the toe of the structure and then to a controlled structure that releases water into the river. “Under flood conditions,” Odie said, “when water rises, the control structure closes and water will collect on the residential side. When the river recedes below the structure, the control structure opens and water releases to the river.”

Dick Koetsier has been a residential property owner in Bragg Creek since 2005. His six properties in the area have all been affected by flood mitigation. He first learned of the possible measures six years ago, when they were proposed by the then-Progressive Conservative government. Koetsier, like Klepacki, is strongly in favour of an instream reservoir on McLean Creek and would have preferred to see that option built. When construction began in Bragg Creek earlier this summer, he was disappointed. “I was sorry to see the area cleared especially because the berms would not have been necessary if McLean Creek would have been built rather than SR1,” Koetsier said in an email, adding that “something had to be done and berms and walls are better than nothing.”

Klepacki says the walls (with a minimum height of 1.2 metres on the landowner side and approximately 2.0 metres on the river side, according to Odie) will cut people off from the Elbow both emotionally and physically. An avid fly fisherman, he also worries about the fate of trout species, whose breeding beds, or redds, could be affected by extra siltation from the project.

Sept2020 Flood mitigation Bragg Creek floating barrierDamage to riparian areas (the zone along a body of water that transitions from wet to dry) is also a concern. Riparian areas help to stabilize riverbanks, filter pollution, and provide habitat for fish, wildlife and vegetation. Lesley Peterson, a biologist with Trout Unlimited Canada, suggests in a report for the ERWP that “softer” approaches to bank stabilization, such as bioengineering, have a less adverse effect on riparian areas than “hard armouring” with large rock, (riprap), gabion baskets and concrete.

In an email to Klepacki, Laura Phalen, a biologist with the Fisheries and Oceans Canada (DFO), said, “We are expecting there to be irreversible harm in the vicinity of the project, and that is why the project required an Authorization, and also requires offsetting.” Phalen added that the harm was expected to be limited in duration, within the project footprint, and within an authorized zone downstream of the project.

Odie said that offsetting measures for the Bragg Creek flood mitigation project are located on Three Point Creek in Foothills County. Because the project is being built to withstand a 1:100-year flood, bioengineering measures such as brush layering, willow staking and root wad installation will not be used. “Green infrastructure such as bio-engineering would most likely not withstand a major event,” Odie said in an email. “In addition, DFO did not accept any sites in the vicinity of the hamlet for implementation of offsetting measures (bio-engineering).” 

Peterson’s report does not directly comment on flood mitigation in Bragg Creek, but she recommends the use of bioengineering in bank stabilization as it can provide “not only engineering function but ecological function.” She adds that continuing to armour rivers with riprap impairs their natural processes and will be a loss to birds, fish and wildlife as well as to those who value and depend on natural riverscapes.

Kamachi and Koetsier said they believe most residents are now in favour of the structures, but Klepacki thinks otherwise. He mentions several landowners who are selling their homes to escape the construction, which is expected to continue for 18 months or more. The east barrier, now being built, will likely be completed by the end of 2020. The west barrier is tentatively scheduled for completion by the end of 2021, with final site clean-up by the end of August 2022.

Kamachi said the structures, when complete, will “absolutely” affect how he interacts with the river. “In fact, I will enjoy it more as there will be more parts of the river to enjoy and engage with,” he said in an email. “Plus it will connect the community even more, attracting visitors which will then help grow our Hamlet business district.” He looks forward to Bragg Creek becoming more of a tourist destination.

For his part, Klepacki says that residents of Bragg Creek, Redwood Meadows and West Springbank are losing their river so that those farther downstream, in Calgary, can have theirs.
“Flood mitigation didn’t have to happen this way,” he said.

Download this PDF document for more information on the project.  pdf Rocky View County - update on Bragg Creek Flood Mitigation (421 KB)  

Click the link to download a PDF copy of this article.  pdf Newsletter article September 2020 (1.47 MB)

 

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