In 2006, the Toba Montrose General Partnership—a wholly owned subsidiary of the Plutonic Power Corporation—awarded Peter Kiewit Sons Co., a subsidiary of Kiewit Corporation, an EPC contract for the design, procurement, construction and commissioning of two run-of-river hydroelectric facilities.
Each facility is comprised of an intake structure, penstock, powerhouse as well as a tailrace channel. A 156-kilometer, 230-kilovolt transmission line connects the powerhouses to a substation at Saltery Bay. Since the project’s completion, it has generated energy at an estimated average of 745 gigawatt hours per year. At peak production there is enough hydroelectricity to power 75,000 homes.
The project scope included constructing and rehabilitating over 90 kilometers of access roads, including 65 kilometers of new road construction and the installation of 61 temporary and permanent bridge structures. The team was required to excavate 2.46 million cubic meters of embankment and rock to construct the two intake structures, two powerhouses and three switchyards, and place 30,000 cubic meters of concrete, supported by 3.050 million kilograms of rebar. A total of 9,600 lineal meters of 2.5-meter-diameter penstock were installed to convey water from the intake to the powerhouse facilities, and power four turbines and generators with a combined capacity of 196 megawatts. Site access was exclusively by air or sea, with the nearest community located about 80 kilometers from the project site.