Annacis Water Supply Tunnel

Location

Vancouver, BC

Owner

Greater Vancouver Water District (Metro Vancouver)

Value

$288 million

The Traylor-Aecon General Partnership, a collaboration between Traylor Infrastructure Canada, ULC, and Aecon Infrastructure Inc., is constructing the Annacis Water Supply Tunnel for Metro Vancouver. This 1.4-mile-long tunnel is one of five new water supply tunnel crossings designed to withstand major earthquakes and expand the region’s water supply capacity.

The project features a 12.7-foot-diameter tunnel with two deep vertical shafts, valve chambers, and the installation of water main pipe and surface piping. Early in the project, the team overcame significant technical challenges posed by artesian groundwater conditions. At the south shaft in Surrey, BC, the team raised the site elevation to counter groundwater pressure and prevent flooding. At the north shaft in New Westminster, where elevation changes were not feasible, depressurization wells successfully lowered the water table, allowing for slurry wall construction.

After arrival and preparation of the custom-built Herrenknecht Earth Pressure balance (EPB) tunnel boring machine (TBM), the TBM launched in early 2024 from the south shaft and is tunneling north under the Fraser River toward the north shaft.

Traylor’s sister company, Ballard Marine Construction, has completed three out of four planned interventions on the TBM and is preparing for the final intervention. The TBM is anticipated to hole through in early 2025. Once the TBM is removed, the team will install and weld an 8.5-foot-diameter steel pipeline with a one-inch-thick wall, ensuring exceptional durability. After installation, the tunnel will be backfilled with cellular concrete.

First Nations cultural layers dating back 7,000 to 10,000 years were discovered at the site. The site’s classification as an archaeological site requires the team to operate concurrently with archaeologists to minimize delays while navigating the limited space around the shaft.