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Vancouver finishes boring Burrard Inlet tunnel

Built with the first slurry tunnel boring machine in Canada, tunnel is 1.1 kilometres long.

October 5, 2021   Rob Blackstien
Infrastructure

The north shaft at the Second Narrows Water Supply Tunnel project

Toronto isn’t the only major Canadian city boasting a tunnel boring project.

Vancouver just wrapped up the excavation at the Second Narrows Water Supply Tunnel, a 1.1-km long infrastructure project designed to make the area’s drinking water system more earthquake resilient and meet increasing demands for safe, high-quality drinking water.

“The tunnel underneath the Burrard Inlet was excavated with the first slurry tunnel boring machine to be used in Canada, and the work was being done up to 100 metres underground,” said Sav Dhaliwal, Chair of Metro Vancouver’s Board of Directors.

This project will help bring clean drinking water from the North Shore to the rest of the region, he added.

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To finish the tunnel, a 50-metre-deep vertical entry shaft was excavated on the north side of the inlet and a vertical exit shaft over 100 metres deep was dug up on the south side. The 135-metre long tunnel boring machine (nicknamed Lynn Marie) began work from the north side in August 2020. The contract was originally awarded to Aecon and the Traylor Bros in late 2018.

The next step in this project will consist of installing three steel water mains (one 1.5 metres in diameter and the other two each 2.4 metres) and connecting them to the existing water system with new valve chambers.

“The new tunnel and water mains will replace three existing shallow buried water mains that went into service between the 1940s and 1970s, which are vulnerable to damage during an earthquake and are nearing the end of their service lives,” said Malcolm Brodie, Chair of Metro Vancouver’s Water Committee.

Ultimately, this $445 million project should be finished in 2025. Take a closer look at the work in the video below.