Metro Vancouver’s Annacis Island Wastewater Treatment Plant Outfall Project has been named the 2025 Canadian Project of the Year by the Tunnelling Association of Canada, a prestigious recognition of engineering excellence in underground construction.
The award recognizes projects that demonstrate exceptional engineering skill, innovation, and a deep understanding of underground construction in Canada. Metro Vancouver shares this award with the project team: Hatch, CDM Smith Canada and Pomerleau Bessac General Partnership.
“This is an excellent example of Metro Vancouver’s commitment to building infrastructure that will serve our growing population and withstand challenges like natural disasters and climate change,” said Mike Hurley, chair of the Metro Vancouver boards of directors. “Congratulations to our outstanding team on another excellent engineering achievement delivered on budget.”
The Annacis Island plant treats wastewater from a million residents across 14 municipalities. Its original 1970s-era outfall pipe needed to be replaced as it was too small, in poor condition, and not up to modern seismic standards. The new tunnel, completed in August 2025, provides increased capacity, enhanced durability, and seismic resilience while improving effluent dilution in the Fraser River.
The project team took an innovative approach to outfall construction, using advanced tunnelling technology to install two 4.2-metre-diameter tunnels beneath areas most vulnerable to soil liquefaction. The outfall tunnel connects to a 2.5-meter-diameter diffuser manifold pipe system installed in the riverbed which is designed to optimally disperse treated wastewater to minimize environmental impact.
The new outfall system addresses future sea level rise and significantly improves the wastewater treatment plant’s resilience, ensuring reliable operation after a seismic event and adaptability to future environmental changes.
Earlier this year, the project also earned an Award of Merit from the Association of Consulting Engineering Companies of British Columbia, in the Municipal & Civil Infrastructure category. The overall budget for the new outfall system is approximately $356 million.
