The Port Mann Main Water Supply Tunnel involves a 1km long tunnel beneath the Fraser River from Surrey to Coquitlam, BC. At depths of up to 60m below ground, the earth pressure reached 6 bar. The tunnel is constructed using an EPB TBM and gasketed precast concrete segmental liner. The tunnel and two shafts were constructed in a variety of soil conditions ranging from soft to stiff clays and silts, to compact to very dense sands and gravels.
