The Port Mann main water supply tunnel project was initiated by Metro Vancouver as part of their critical infrastructure network upgrades to replace the existing pipeline constructed in the early 1970s.
The new, CAD$240 million tunnel ensures continued, reliable delivery of safe drinking water while more than doubling the capacity of the existing main.
The new tunnel is capable of withstanding a 1 in 10,000 year seismic event. The tunnel, 1 km long and 3.5 m in diameter, contains a 2.1 m diameter steel water main running between two 60+ m vertical shafts.
To accommodate 6 m of movement in surrounding liquefiable soils, the 50 m vertical pipe runs in the system are unrestrained except at the endpoints at the shaft base and valve chamber outlets.
This feature allows the pipe to bend and yield, while remaining functional in case of the design level earthquake.
The Ausenco-led design team provided detailed engineering and construction support. Subconsultants included McMillan Jacobs Associates (tunnel and slurry wall design); Golder Associates (geotechnical, environmental and permitting services); and others.
Considerations were given to environmental, social and archaeological impacts to assist in obtaining the required permits and approval from the Fraser River Estuary Management Program.
This project received the 2016 Canadian Innovation Project of the Year award from the Tunnelling Association of Canada and the 2017 ACEC-BC Award of Excellence in the Municipal & Civil Infrastructure category.