Annacis Water Supply Tunnel


Vancouver, BC


Greater Vancouver Water District (Metro Vancouver)


$288 million

Metro Vancouver selected the Traylor-Aecon General Partnership, a consortium of Traylor Infrastructure Canada, ULC and Aecon Infrastructure Inc., to construct the second of five new water supply tunnel crossings in the region built to withstand a major earthquake and expand the capacity of the existing system.

The project includes construction of a 1.4-mile-long TBM tunnel; two deep vertical shafts; construction of valve chambers; and installation of water main pipe and surface piping. Key project challenges include very high tunneling face pressures requiring mixed-gas ‘bounce-diving’ for interventions, very short-mode TBM Launch at high (~6 bar) pressure requiring the use of a ‘launch- can’ and a hydraulic mucking system (slurry circuit and slurry treatment plant) for start-up, artesian groundwater conditions requiring groundwater depressurization to facilitate shaft construction, highly compressible near-surface geology requiring surcharge pre-consolidation and reinforced engineered fills to improve site stability, and tunneling beneath critical infrastructure and sensitive property owners requiring robust geotechnical instrumentation and monitoring.