Bonnybrook Wastewater Treatment Plant – Various Projects

Bonnybrook is the City of Calgary’s largest wastewater treatment plant and serves over 600,000 citizens. Graham is the primary construction contractor for the upgrade and expansion program at this facility, the largest cold-weather BNR plant in the world.

Prior to the expansion and upgrades program the plant had an average capacity of 396 ML/day and a peak capacity of 1,096 ML/day.

The Bonnybrook Wastewater Treatment Plant (BBWWTP) is the largest of Calgary’s three wastewater treatment facilities, with an average treatment flow of 396 ML/day and a peak capacity of 1,096 ML/day (up to 1,390 ML/day during wet weather events). Originally constructed in the 1930s, Bonnybrook has undergone extensive upgrades and expansions over the decades to support the city’s growing population.

Graham began work at Bonnybrook in 2002 and has maintained a continuous presence on-site, delivering more than 55 distinct contracts. These projects have ranged in scope and value—from an $8,000 temporary heating installation to the current $483-million Construction Management contract for the Plant D Expansion.

Historical and Ongoing Projects

Scheduled for completion in July 2028, the Plant D Expansion will increase the plant’s treatment capacity from serving 950,000 to 1.37 million people, supporting population growth through the mid-2030s. Below is a summary of some key Graham-led projects at Bonnybrook:

• 2012: Awarded a $67-million contract to construct the new Headworks Building, one of the most advanced facilities of its kind in North America, designed to meet the demands of a growing population.
• 2014: Began the $100-million Plants B and C Upgrades while concurrently performing pre-construction services for the Plant D Expansion.
• 2016: Construction began on the $78-million Dewatering Building, developed to process increased volumes of biosolids. This facility removes water from anaerobically digested biosolids and conveys the solids to the City’s composting facility. It was constructed in parallel with the Plants B and C upgrades.
• 2016–ongoing: The Plant D Expansion spans pre-construction, construction, and post-construction phases across 16 work packages. Key elements include new primary clarifiers, bioreactors, secondary clarifiers, effluent conveyance systems, a filtration building, thermal hydrolysis processing, UV disinfection, and a new outfall. Upgrades also include improvements to existing sludge digesters, gas holding systems, and flood protection infrastructure.

Additional recent contracts at Bonnybrook include:

• A $23-million Electrical Upgrades & Expansion Program (2017)
• A $65-million Co-generation Expansion (2019)
• A $5.4-million, five-year Safety Repairs Program (2022)
• A $3.6-million Digester Gas Coating Repair initiative (2022)

Read more about this project in the Summer 2024 issue of DDC Journal (pgs. 98-101)