Bonnybrook Wastewater Treatment Plant is the largest of three wastewater treatment plants serving Calgary and area. Originally built in the 1930’s, Bonnybrook is undergoing its most substantial upgrade to date. With an investment of more than $1-billon dollars over the span of 10 years, it is expected that Bonnybrook will see its total treatment capacity increase to nearly 1.4 million citizens when completed in 2026. In 2021, the project made significant progress. At Plant D, the greatest number of projects were completed and commissioned including the installation of two new primary clarifiers and six additional secondary clarifiers. This project also entailed the construction of three secondary treatment bioreactors and retrofits and upgrades to existing solids handling digesters, and the UV disinfection facility. Lastly, as part of this Plant D upgrade, a new bio-gas handling storage facility was completed and commissioned. In Spring of 2021, a new outfall was commissioned and put into service. This new larger outfall was built 900 m further downstream to provide additional flood resiliency and an improved diffusion system to enhance environmental performance.