The Effect of Geology on the Dinkey Creek Project

by Arthur B. Arnold, Bechtel Civil Inc, San Francisco, CA, USA,
John P. Sollo, Bechtel Civil Inc, San Francisco, CA, USA,

Document Type: Proceeding Paper

Part of: Water Power '87


The proposed Dinkey Creek Project is located about 40 miles northeast of Fresno, California. The project consists of a 360-foot high rockfill dam, two powerhouses, 41,600 feet of power tunnels, and four vertical shafts, and a 23,500 foot long diversion tunnel. The bedrock throughout the area consists of igneous and metamorphic types overlain by a relatively thin layer of residual soil, talus, and channel alluvium. The tunnels and associated shafts are anticipated to be excavated by tunnel boring machine and raise borers in hard, massive, granitic rock, which ranges in composition from grandiorite to quartz diorite. Some very hard, moderately fractured metamorphic rock, either quartzite, marble, or schist, may also be encountered. Exploration for the tunnels, included approximately 7000 feet of core drilling. To determine the variation of minimum total stress with location and depth, 40 hydrofracturing and 73 hydrojacking tests were performed that resulted in some relocation of the tunnels and redesign of the penstock linings.

Subject Headings: Geology | Rivers and streams | Shafts | Hydro power | Power plants | Bedrock | Layered soils | Tunneling | California | United States

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