American Society of Civil Engineers

Construction of Grand Coulee Third Power Plant

by Donald J. Duck, M.ASCE, (Deputy Dir. of Design and Construction, Bureau of Reclamation, U.S. Dept. of the Interior, Denver, Colo.)

Journal of the Construction Division
, Vol. 101, No. 4, December 1975, pp. 869-881

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Document type: Journal Paper
Abstract: Construction of Grand Coulee Third Power Plant, begun in July, 1967, will add 3,900 mW to the existing 2,329-mW capacity of Grand Coulee. Major items of work for the total project include modifications to electrical facilities; over 22,000,000 cy yd (17,000,000 cu m) of excavation; removal of 260 ft (79 m) of existing concrete dam; construction of a 200-ft (61-m), 1,275-ft long (389-m) concrete gravity dam containing over 600,000 cu yd (460,000 cu m); construction of a 1,128-ft long (344-m) power plant; and a 500-kV switchyard. Six 40-ft diam (12-m) steel penstocks will deliver 30,000 cfs (840 m³/s) each to three 600-mW and three 700-mW turbine-generator units. For the first three 600-mW units, turbine capacity is 820,000 hp at 285-ft (86.9-m) head) and 72 rpm, and generator capacity is 615,385-kVA, 97.5% power factor; each rotor is 60 ft (18 m) in diameter and weighs 1,936 tons (1,756,000 kg). Upstream control of penstocks is provided by 29-ft by 43.5-ft (8.8-m by 13.3-m) wheel-mounted gates.

ASCE Subject Headings:
Concrete dams
Electric transmission lines
Gravity dams
Hydro power