Penstock Monitoring System in Active Landslide Areas

by Jeffrey E. Twitchell, STS HydroPower Ltd, Sacramento, United States,
Timothy K. Dahlstrand, STS HydroPower Ltd, Sacramento, United States,

Document Type: Proceeding Paper

Part of: Waterpower '91: A New View of Hydro Resources


During initial planning of a high-head, five megawatt hydroelectric plant in Northern California, it was identified that the entire three-mile length of a 40 inches welded steel penstock would pass through dormant and active landslide areas. Annual slope movements along the penstock alignment ranged from fractions of an inch to three feet. The penstock was designed for conventional cut and cover installation, except for a section which is in an area of extreme slope movement. The penstock is located above ground in the extreme slide area and is designed to allow the active slide to move under the penstock. In addition, an automated, remote penstock stress monitoring system was designed and installed to monitor penstock performance throughout the life of the project. This paper describes the unique penstock design and its geologic setting, including an overview of the unstable slope conditions. The data collection hardware and software are described, as are the results of the first year of monitoring.

Subject Headings: Conduits | Landslides | Sliding effects | Hydro power | Slope stability | Welding | Alignment | Automation | California | United States

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