Excavation to start soon on Burnaby Mountain Tunnel
29 April 2021Crews are preparing to start excavating a 2.6km tunnel through Burnaby Mountain, western Canada, as part of a major expansion that will allow the country to better convey its crude oil to market.
Seen as a milestone in the ‘Expansion Project’ of the Trans Mountain Pipeline (TMP), the Burnaby Mountain Tunnel will connect Burnaby Terminal – the TMP end-point and a major distribution hub for crude oil and refined products – to Westridge Marine Terminal, Vancouver.
Located at up to 130m below the surface, the tunnel will be excavated by a 4.43m-diameter TBM that will mine 24 hours a day, seven days a week. Geological investigations have revealed the alignment geology to comprise deep overburden material overlaying weak sandstone (9MPa) and conglomerate. The bore is expected to take 200 days to complete at a rate of around 15m per day. As it advances, the machine will install precast concrete segments – six to each ring. Around 40,000m3 of soil will be excavated and taken out of the tunnel in muck cars.
Owner TransMountain’s contractor Kiewit Ledcor TMEP Partnership (KLTP) has so far constructed reinforced concrete piled retaining walls up to 20m high and 70m long at both portals. Westridge Marine Terminal, where a 100-pile wall has been constructed, is where tunnel boring will start.
Upon completion of the tunnel, three 762mm (30in) pre-welded steel pipelines will be installed, one on top of the other, supported by steel racks. Following pipe installation and weld testing, the tunnel will be back-filled with low-density concrete. The tunnel’s entry and exit sites will then be back-filled and landscaped.
The Expansion Project is part of the Trans Mountain Pipeline which will convey crude and refined oil from Edmonton, Alberta to the coast of British Columbia. TransMountain is owned by the federal government of Canada.
