Construction of the new Ashlu Creek hydroelectric project in British Colombia, Canada is planned to start in early 2005.
Developed by Ledcor Power, the 49MW run-of-the-river scheme comprises a powerhouse at elevation 550m, a 4.2km long x 4.1m diameter power tunnel under a maximum 550m overburden and a 146m raisebore drop shaft to an intake structure at elevation 270m.
A fixed price, turnkey contract has been awarded to the Vancouver-based division of Peter Kiewit & Sons as prime contractor. Frontier Kemper Constructors Inc. under a fixed-price turnkey subcontract will excavate the power tunnel using an open Wirth TBM through granite of more than 200MPa.
The tunnel is designed by Hatch Mott MacDonald with surface structures designed by Knight Piesold in association with Amnis Engineering.
Geological mapping of the project area has identified at least six inferred regional tending fault/shear zones crossing the tunnel alignment. According to tunnel design manager Dean Brox, for Hatch Mott MacDonald, two of these zones are quite visible from surface expressions coincident with re-direction of Ashlu Creek from a northwest-southwest to a northeast-southwest orientation.
Excavation of the power tunnel, which will be supported with rockbolts and shotcrete, should start in early 2005 and require about 18 months to complete.
