Skip to main content
skip to content Français Search
Start of main content
Bonnybrook Wastewater Treatment Plant Expansion Program

Expanding the world’s largest cold-weather BNR plant

Calgary, Alberta

The Bonnybrook Wastewater Treatment Plant is one of the largest biological nutrient removal (BNR) plants in Canada and the largest cold-weather BNR plant in the world. Influent temperatures reach a minimum of 10 C with air temperatures as low as -40 C in the winter.

Population growth and increasingly stringent treatment standards have been the primary drivers for numerous plant expansions since it was constructed in 1932. Currently, the plant provides treatment up to an average capacity of 396 ML/d and peak capacity of 1,069 ML/d to serve 946,000 Equivalent Population (EP), but it is nearing its installed capacity.

Upgrade projects for Secondary Plants B and C are under development as interim measures to provide additional capacity. Parallel to these upgrades, the design of a full treatment plant expansion (Plant D) is currently underway to increase the installed capacity by 325,000 EP (135 ML/d). Peak flow capacity will be increased to 1,390 ML/d.

The project includes upgrades to primary influent conveyance, primary treatment, primary effluent conveyance, BNR process, secondary clarification, effluent filtration, UV disinfection, plant outfall, chemical and process utility systems, secondary sludge thickening, secondary sludge dewatering, thermal hydrolysis of dewatered waste activated sludge, sludge digestion, and biogas management.

The need for additional treatment in the City of Calgary, including the requirement for future transfer of flows from south catchments to the plant, makes the completion of the Plant D expansion project a priority.

View A Project Near You

Find Stantec projects near you
End of main content To top