Design of the Tunnel System for the Terror Lake Hydroelectric Project

by Michael Morris, M-K Engineers, San Francisco, CA, USA,

Document Type: Proceeding Paper

Part of: Waterpower '85


The Terror Lake Hydroelectric Project, Kodiak, Alaska, contains a 5-mile-long (8. 1 Km) power tunnel with supplementary stream diversions entering it by two shafts along its alignment. High flows down the diversion shafts can introduce considerable quantities of entrained air, and unless proper provision is made to control the air it can accumulate within the tunnel system, and finally release itself with explosive force and damage structures. Controlling design requirements have been developed at the Norwegian Hydrodynamic Laboratories, Trondheim. Their application led to a solution where air can enter the system at one diversion shaft, but is removed either through the other diversion shaft or at a specially designed air release duct at the gate shaft. The diversion shafts also function as surge shafts, and surge chambers were designed to meet the adopted shutdown and startup criteria for the powerhouse.

Subject Headings: Tunnels | Hydro power | Shafts | Lakes | Project management | Power plants | Construction management | Rivers and streams | Alaska | United States

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