Economical Solution for Flood Overtopping Potential at Senator Wash Dam

by Dorothy D. Frawley, U.S. Bureau of Reclamation, Boise, United States,
J. Lawrence Von Thun, U.S. Bureau of Reclamation, Boise, United States,

Document Type: Proceeding Paper

Part of: Geotechnical Practice in Dam Rehabilitation


A breach analysis of North Dike for overtopping with the crest modified to the lower elevation was required to ensure the breach discharge would be adequate to prevent overtopping of Senator Wash Dam and Squaw Lake Dike. The shape of the fully developed breach, and the time required to develop that breach, were estimated. Flood routings were performed for three cases: the most rapid estimated failure, a slower failure, and the best estimate of failure time. Additional flood routings were performed for the worst case of no failure at North Dike. The studies necessary to determine the design requirements and most critical design factors are described in this paper. Use of a breach initiation fuse plug to ensure acceptable breaching performance was found to be necessary based on these studies. An erodible section installed on the downstream side of North Dike, is designed to act as the fuse plug during overtopping, hastening the formation of a breach. Erosion will initiate in a funnel-shaped depression which simulates a pilot channel on the downstream half of the crest. This action will induce rapid erosion of the fuse plug material. A description of the design and construction considerations for the required features are included in the paper.

Subject Headings: Wave overtopping | Floods | Legislation | Failure analysis | Dams | Flood routing | Economic factors | Embankment dams

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