WC146 JanFeb 2026 - Magazine - Page 16
TOP 50 PROJECT
Plants are for
Growing
Population boom drives expansion of
Calgary’s Bonnybrook WWTP
BY SAUL CHERNOS
ITH WORK to install a bioreactor and two
new clarifiers at one of Calgary’s largest
wastewater treatment plants winding down, a
nine-year-long, $640 million expansion project to accommodate the city’s rapidly growing population is finally coming to a close.
Built in 1932 next to a CN Rail line on the west bank
of the Bow River, the Bonnybrook Wastewater Treatment
Plant serves the north, northwest, west and central portions of Calgary, as well as suburban communities such as
Airdrie, Cochrane, T’suu Tina and Elbow Valley through
service contracts.
Despite its age, Bonnybrook has performed with little
complaint, retaining some of its original infrastructure
while seeing the addition over time of multiple bioreactor
trains and other treatment systems and technologies.
Bonnybrook started out as a purely primary treatment
facility, with secondary systems incorporated in the
1960s as part of what’s become known as Plant A. Further secondary treatment capacity was added two decades
later with the construction of Plant B, and when Plant C
brought in even more secondary treatment and introduced ultraviolet disinfection in the 1990s Bonnybrook
had blossomed into one of the largest biological nutrient
removal (BNR) facilities in Canada and the largest
cold-weather BNR plant in the world.
Still, steady and at times sharp population growth
forced the City to face the prospect of Bonnybrook eventually exceeding capacity. Gabrielle Jablonski, senior project engineer with the city’s infrastructure services department, says the estimated population base within Bonnybrook’s service area was 1,041,000 in 2017, with the
facility designed to accommodate just 1,258,000 users.
While pressures from growth might not have been evident to the public, wastewater plants typically reach a
Saul Chernos is a freelance
writer for Water Canada.
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WATER C AN ADA • JANUARY/ FEBRUARY 2026
City of Calgary
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