Sunnyside Flood Barrier

To protect Sunnyside from future flooding, the Flood Mitigation Measures Assessment​ (FMMA) report, approved by Council in spring of 2017, recommended that a combination of mitigation solutions that work together to create a flexible and adaptable flood risk management program. Each piece of the strategy provides great benefits independently, but together, they ensure the most effective flood protection strategy.

Below is a summary of this multi-measure approach to building flood resiliency that includes the construction of a new upstream reservoir, as well as changes to the TransAlta’s Ghost Reservoir and the construction of community-level flood barriers.

Learn more about Calgary's Flood Mitigation and Resiliency Plan.

After working with the community and completing a Triple Bottom Line evaluation to explore different options for a flood barrier in Sunnyside, Council approved the 1 in 100-year flood barrier height that will help protect people, homes and businesses in Sunnyside/Hillhurst from river flooding.

Benefits of the 1 in 100-year flood level barrier height

• Reduces the 2013-level flood risk, which will be further reduced by current and future upstream reservoirs on the Bow River.
• Less disruptive to the community look and feel
• Increases the ability to protect vulnerable populations
• Meets the provincial and federal flood standard (1 in 100-year)
• Provides the building blocks for future climate resiliency

Following direction from Council, the barrier will be built to withstand the 1:100-year flood event having a peak flow rate of 2090 m³/s at Sunnyside. This is greater than the recorded peak flow rate of the 2013 flood that was 1840 m³/s.  The 1:200-year event peak flow rate is 2710 m³/s.  To withstand the 1:200-year flood the barrier would need to expand in length by approximately 1 km and in height by 0.7 m along its entire length. 

Still, designers investigated modifying certain components of the flood barrier to simplify possible future expansion of the barrier within its footprint and within its approved budget.  Wider concrete footings, deeper pile depths and greater vegetation setbacks were considered but did not offer appreciable current benefit (i.e. not cost effective) for a possible future expansion.  Also, for a given length and height, there are numerous consequent design decisions that would need to be reconsidered if the level of service was to be increased. Such considerations are better addressed at the time of expansion. 

The City is exploring how to regulate land use in river valleys through the Calgary River Valleys Project This work follows, the Government of Alberta’s update of Flood Hazard Area maps for communities across the province.  This will ultimately lead to an update of the Land Use Bylaw. Flood Hazard maps are based on the 1:100-year flood and include ‘protected areas’ where flood protection is provided, such as Sunnyside and Hillhurst. Appropriate regulation for such areas is being explored. Land use regulation may change in Sunnyside or Hillhurst, but it is not affected by the barrier’s height above the 1:100-year flood.

The location of the flood wall is not yet finalized; the location will be refined as the design progresses. The general alignment of the flood barrier has been determined. We are currently in the detailed design stage, which takes a closer look at the constraints and refines the design  such as the exact location and type of flood barrier over the 1.9 km length.

The 1 in 100-year option is the recommended barrier height for Sunnyside because it’s reflective of the best balance between social, environmental and economic considerations. It’s an investment that enhances the safety of residents and our ability to protect those most vulnerable, while having a lesser impact to the community look and feel. The 1 in 100-year option meets the federal and provincial flood protection standards. When constructed, it will immediately reduce Sunnyside’s risk from a 2013-level flood. This option will be further enhanced by current and future upstream reservoirs on the Bow River, allowing it to manage even larger floods.

Feedback garnered through public engagement will be used to inform elements such as public amenities and open space adjacent to the flood barrier and will not inform any design decisions for the flood barrier. We do not anticipate that engagement for the Memorial Parkway project will delay the overall construction timelines for the Sunnyside Flood Barrier project.

As we advanced the flood barrier design, we recognized the significant impact this project would have on the area. During this time, it also uncovered some opportunities to integrate the flood barrier into other work that was happening in this area and a desire to capitalize on this moment to protect and enhance the area as much as possible while adding the flood protection. 

To help increase flood resiliency and create spaces that enhance the connection with the river, natural environment and commemorate our heritage, we’re combining this work through an integrated program. We recognized that by taking a more integrated approach we could achieve the best outcome for the area.

As part of The City’s emergency response plan, we are ready to respond, if needed, in areas that are still vulnerable to river flooding. We stockpile riverbank protection and temporary barrier materials and each spring our City teams review their plans, conduct site visits and train crews.  

In addition, every spring, infrastructure such as water main valves, stormwater outfall gates, lift stations and pump are prepared, tested or positioned for flood season to reduce potential damages during a flood.

PCL Construction Management Inc. (PCL) has been selected as the construction manager for delivery of the Sunnyside Flood Barrier project and public realm improvements.

We are using a construction management approach to allow the project team greater design flexibility and project control to address schedule and community impacts.

We know that there are several historical and socially significant sections of the Sunnyside Flood Barrier alignment, so using a construction management approach allows more time to work through the details of those while getting started on the more straightforward areas.