Annacis water supply tunnel engineering services
Enhancing water capacity and seismic resilience beneath the Fraser River
Metro Vancouver
|
Vancouver, Canada
|
2017–2028
2.3-km tunnel to be constructed under the Fraser River.
US$425 million in project costs.
Provided full-scope engineering services for tunnel excavation and construction.
Challenges
- To meet growing potable water demand south of the Fraser River, Metro Vancouver proposed construction of the Annacis Water Supply Tunnel (AWST) as part of the Greater Vancouver Water District (GVWD)’s water distribution system.
- The tunnel would accommodate a steel carrier pipe approximately 2.6 m in diameter and be designed for long-term scour protection and structural resiliency to withstand a major earthquake event.
- Metro Vancouver needed an engineering partner to support excavation deep underneath the Fraser River between the city of Surrey (to the south) and the city of New Westminster (to the north).
Solutions
- Retained by Metro Vancouver to perform full-scope engineering from preliminary and detailed design to construction engineering for the 2.3-km-long tunnel running under the Fraser River, along a generally north-to-south axis.
- The tunnel excavation requires the use of a pressurized face tunnel-boring machine (TBM) with the immediate installation of supporting consisting of segmental pre-cast concrete tunnel lining (PCTL).
- Following PCTL construction, a final 2.6-m-diameter steel carrier pipe will be installed within the shafts and tunnel, and will be grouted in place. Shafts will also be constructed on both sides of the river to facilitate tunnel excavation.
Highlights
- Provided critical infrastructure for Metro Vancouver’s future water needs, improving the water distribution system’s resilience and emergency preparedness.
- Deep tunnel design allowed for minimal surface disruption during tunnel excavation and construction.
"We always want to work with the best in the industry. We chose a partner that would be together with us from feasibility studies into construction to prove the process design. The importance of this was to have a consistent partner that we can rely on. Thats why we chose a tier 1 partner like Hatch."