Site clearance and preparation work has begun for a 14.4km long water tunnel project in Canada, whilst prequalified contractors await the issue of tender documents in early May.
The Seymour-Capilano scheme will allow the treatment of water from two discrete watersheds at the Greater Vancouver Regional District’s (GVRD) single new treatment plant to the northeast of Vancouver.
Pacific Liaicon & Associates (PLA), a member of the SNC-Lavalin Group, has been employed by GVRD as project and contract manager for the scheme. Andrew Saltis, managing the tunnels part of the contract for PLA, told T&TI that eight contractor organisations had been prequalified: Bilfinger Berger AG; Frontier Kemper/Aecon joint venture; Guy F Atkinson LLC; Insituform Technologies Ltd.; JF Shea Construction Inc.; Kenny Construction Company; McNally/ Obayashi joint venture; and Kiewit/ Traylor joint venture. Saltis added that Hatch Mott MacDonald where the project design consultant and it was hoped that the construction contract could be awarded by late June. The construction is scheduled to be completed by 2008 and is entirely funded by GVRD.
The expected rock type will be grandiorites and whilst GVRD did not express a preference for a TBM manufacturer, it has said that final selection is at the discretion of the successful contractor, so long as it conforms to the specifications and information in the project geotechnical reports.
The twin 3.7m diameter tunnels run for 7.2km at depths varying between 160m and 640m below the surface as they pass under Grouse Mountain. At the Capilano end, they are accessed by a 270m deep shaft that will be raisebored, with spoil being collected from within the tunnel after excavated.
The 12m diameter Seymour shaft is 185m deep and will be used as the drive shaft for the TBMs. Currently the plan is for roughly the first 150m of tunnel from the shaft to be excavated by drill and blast.
The option is then open to the contractor to select rail or conveyor systems for the TBM spoil removal. At each end of the tunnels, there will be a steel lining grouted in place, the central sections of the tunnels will be unlined.
The tunnels will allow water from Capilano to be pumped to a new treatment plant, where water from Seymour will also be processed. Treated water can then be sent back along the parallel tunnel by gravity to Capilano for distribution. Both of the project shafts are situated in parkland, raising concerns about construction work and its possible impacts. The GVRD held public consultations and concluded that the tunnels were preferable to two separate plants.
