Challenging Site Conditions Lead to Unusual and Innovative Powerhouse Design Features

by David W. Moller, Pacific Gas & Electric Co, United States,

Document Type: Proceeding Paper

Part of: Waterpower '89


Pacific Gas & Electric Company's recently completed Newcastle Powerhouse is located on the shore of Folsom Lake near Auburn, California. The $26 million facility uses a single vertical Francis turbine to generate 12.7 nw of power. Unusual and innovative design features include: siting the powerhouse completely below grade to maximize net head during 50 ft. seasonal tailwater fluctuations, accommodate steep topography, and minimize visibility; use of a unique shape for the powerhouse structure to minimize excavation support and facilitate multi-stage construction; use of a 266 ft. long, 47 ft. high, curved reinforced earth cofferdam loaded on one side during powerhouse construction then loaded on the opposite side as a retaining wall during project operation; use of a water-reactive chemical applied to the excavated rock surface, prior to concrete placement, to waterproof the exterior walls of the powerhouse; use of both steel and concrete pipe on the 7 ft. diameter by 5600 ft. long penstock. Additional design features are discussed in the paper.

Subject Headings: Power plants | Innovation | Hydro power | Electric power | Reinforced concrete | Concrete pipes | Excavation | Soil stabilization | California | United States

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