The Underground Powerhouse And Tunnels For The Bad Creek Pumped Storage Project - A Case History

The underground portion of Duke Power Company's Bad Creek Pumped Storage Project in northwestern South Carolina consists of a powerhouse cavern (132 m. long, 23 m. wide, 50 m. high), 407 meters of shafts and approximately 3615 meters of tunnel, both lined and unlined, with diameters varying from 4.2 meters to 9.0 meters. A case history is presented, including the early pilot tunnel exploratory work and how this affected design, the design of the project, and the excavation, rock support and tunnel lining work. Problems and experiences encountered during the construction are given. The effects of high horizontal insitu stresses in the granitic gneiss are discussed along with solution taken.