Expansion and upgrades to Bonnybrook Wastewater Treatment Plant turns waste gas into power and keeps Calgarians flushing for years to come

We often take for granted that when our toilets flush, the waste just disappears, never to be seen again. However, the level of technical and specialized knowledge, skills and equipment that's needed to operate and maintain a facility that takes care of our wastewater and protects the health of our rivers is immense, and exceptionally complex. That’s why The City is investing over $1 billion in a program of extensive upgrades and expansions to the Bonnybrook Wastewater Treatment Plant to protect the environment and accommodate our city’s future growth.

Bonnybrook is the largest of The City’s three wastewater treatment plants, which serves the north part of the city. Over its 90-year history, the plant has undergone numerous upgrades and expansions and was also inundated with water during the 2013 flood. The current expansion project will increase the plant’s treatment capacity by 30 per cent to meet the needs of a growing city and will also include the addition of flood protection measures to protect this critical infrastructure from future river flooding.

Part of the upgrades also includes the near completion of a co-generation energy project that will create substantial savings to the plant’s utility costs and reduce the plant's greenhouse gas emissions. The work will expand Bonnybrook's Power Generation and Heating facility by adding a new, 4.6-megawatt gas turbine and 0.6-megawatt steam turbine. This new system will use biogas, a byproduct of the wastewater treatment process, and a free and renewable source, for power generation and heating, thereby substantially reducing the plant’s utility costs by minimizing the need to rely on external sources of electricity and natural gas. After the work is complete, the plant's onsite power generation capacity will meet or exceed the plant's electrical demands, capable of achieving electrical energy self-sufficiency, with the capability of exporting excess power back to the grid.

This upgrade is also good for the environment. Orin MacIntyre, Leader of Wastewater Treatment Engineering with Utilities Delivery says, “The new system will reduce Bonnybrook's greenhouse gas emissions by about 17,500 tCO2e/year by reducing natural gas use and electricity import, minimizing biogas flaring, and improving plant energy efficiencies. This is roughly the equivalent of taking 5,600 cars off Calgary’s roads.”

The City is committed to mitigating the effects of climate change, and Bonnybook is leading by example in the production and use of green energy. With a total generation capacity of 10-megawatts, Bonnybrook is now listed on the Alberta Electric System Operator (AESO)’s website as one of 13 sites in Alberta which generates power from a biomass source.

The upgrades and expansion projects started in 2015 and all projects are expected to be completed by 2030. Learn more about these projects at

For more information about how we’re investing in services that matter to Calgarians, visit