ISL was engaged by The City of Calgary to conduct the design and construction of stabilization and rehabilitation measures for multiple sites that were severely eroded by the June 2013 flood event. ISL managed five riverbank stabilization programs at the following locations: Deane House, Bowmont Rail Bridge, Alyth Yard Bridge, 85 Street NW Bridge and the 16 Avenue NW Outlet. ISL was also commissioned to conduct the Deane House Flood Mitigation project. The engineering design involved conducting an evaluation of the June 2013 flood impacts at each site as well as the previously proposed rehabilitation techniques. The bank slopes and floodwater levels were analyzed to determine the most effective methods to mitigate future flood effects and erosion.
The final bio-engineered solution was developed based on the steepness of the bank slopes, the predicted water velocities at higher return periods and the local growing conditions of each site. Various types of native vegetation were introduced at the specified locations to stabilize the earth-fill used to restore the bank slopes. Additionally, by planting specific types of vegetation at normal water levels, such as willows, we were able to provide natural shading zones for the desired fish habitats. Riprap protection was also incorporated into the design to complement the natural riverbed materials and to provide scour protection.
The restoration of pathways and adjacent fences was considered part of the site restoration activities, anderosion and sediment control measures were incorporated into the final design. To facilitate the replacement of a damaged pathway at the Deane House location, a gabion wall structure was proposed as a tie-in to the existing concrete retaining wall in the area.