Metro Vancouver has opened a new $240-million tunnel built under the Fraser River to ensure drinking water keeps flowing to Surrey and South-of-Fraser residents in the event of an earthquake.
The critical phase of the project saw the Port Mann Water Supply Tunnel gradually burrowed out by a massive tunnel boring machine dubbed ’Squirrel’ during 2014-15.
The new one-kilometre-long tunnel is 3.5 metres in diameter and located more than 30 meters below the riverbed.
It more than doubles the capacity of the old water main and is built to withstand both an earthquake and river erosion forces, which knocked the old main offline in 1997 and forced temporary water restrictions in Surrey.
The nearly six-year project posed major challenges due to difficult soil conditions and high groundwater pressures. At one point engineers had to inject liquid nitrogen to harden the soil in front of the tunnel boring machine so it could be repaired.
View inside the Port Mann Water Supply Tunnel during construction.