New Sunnyside Stormwater Lift Stations provide Calgarians with greater flood resiliency

Extreme weather events are increasing, creating significant risk to our communities. The 2013 floods in Calgary had a substantial impact on the City, its residents and businesses, and their property. Many property owners in the community of Sunnyside, located north of the Bow River and downtown Calgary, experienced flooding and basement damage.

Following the disaster, the City implemented a number of flood resiliency projects. To provide greater flood protection to the Sunnyside community, the City retained Associated Engineering to upgrade its existing Sunnyside Stormwater Lift Station and add a second stormwater lift station further to the east. Led by Project Manager, Shane Thompson, Associated Engineering provided community engagement, triple-bottom-line options analysis, and design and construction services. The project increases the combined stormwater pumping capacity and improves the overall flood resilience of the community.

The existing lift station had a nominal capacity of 900 litres per second; however, under flood conditions, capacity was as low as 500 litres per second. The new lift stations are designed to a nominal capacity of 2,000 litres per second and 1,000 litres per second, respectively. The lift stations’ capacities can be maintained even under a high river water event, unless the water elevation exceeds the river bank.

During the 2013 floods, safe access was not possible to the existing lift station’s pumps, generator, and heating, ventilation and air conditioning system. In the new lift stations, the motor control centre and a 750 kilowatt standby generator are all critical equipment that have been located above the 1:100 year flood level to allow access to the equipment during flood conditions.

Shane tells us, “It was a challenge to upgrade the existing lift station on a small parcel of land next to an apartment complex, while keeping the existing lift station operational to help ensure the community was still protected during high rainfall events.”

In the limited area, the team had to accommodate the required outdoor air intake for the standby generator to operate optimally. We designed a third story for the lift station to house large, air intake louvres, which were fitted with acoustic insulation to dampen noise. Frequent community communications were important and minimized disruptions to the surrounding residents.

The new stormwater lift station was also carefully planned. We used a triple-bottom-line analysis to evaluate several proposed locations for the new lift station with respect to social, environmental, and economic risks and opportunities. The optimal location selected considered the natural and built environments and significant public use of the surrounding area. The design included a public exercise area, drinking fountain, and regrading of bike and pedestrian pathways to improve public amenities. A rooftop solar photovoltaic system was also installed to provide power to the building’s lighting and building mechanical systems.

Process Engineer, Greg Cooper, tells us, “We used an existing 1,050 millimetre diameter concrete forcemain to hold the new forcemain, an epoxy-coated, steel pipe. We milled and epoxy-lined the inside of the concrete pipe to slide the new pipe inside the existing pipe.” We also upgraded the stormwater Outfall B47 to dissipate the increased stormwater velocity and volume.

“Associated has been crucial in providing us the multi-disciplinary expertise required in constructing the Sunnyside Lift Stations.” - Susha Prakash, P.Eng., City of Calgary Project Engineer, Project Engineering - Underground

The upgraded Sunnyside Stormwater Lift Station was successfully commissioned in two stages, Stage 1 in 2019 and Stage 2 in 2020. The new lift station was commissioned in late-2020. Commissioning during the COVID-19 pandemic required additional planning and precautions to protect the safety of the commissioning team.

Key Associated team members included Shane Thompson, Greg Cooper, Gabriel Jean, Mohamed Aly, Joe White, Mark Ingalls, and Ryan Jalowica. The City of Calgary was represented by Susha Prakash, P.Eng. and Karen Matharu, P.Eng. with whom Shane and Greg worked in close collaboration to successfully deliver this important flood resilience infrastructure for the community.