American Society of Civil Engineers

RCC: Rehab Results

by Francis G. McLean, M.ASCE, (Chief, Geotechnical Engrg. and Embankment Dams Branch, U.S. Bureau of Reclamation, Denver, CO) and Kenneth D. Hansen, F.ASCE, (Sr. Water Resources Engr., Portland Cement Association, Denver, CO)

Civil Engineering—ASCE
, Vol. 63, No. 8, August 1993, pp. 46-49

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Document type: Feature Article
Abstract: Thirty dams have been modified with roller compacted concrete in order to provide additional spillway capacity and for safe overtopping of embankment dams. In the national dam safety inspection performed by the U.S. Army Corps of Engineers from 1977 to 1981, hydraulic deficiencies lead the list of major problems—specifically, the inability of a dam to retain or safely pass the Probable Maximum Flood. Common solutions for solving a hydraulic deficiency include raising the dam to increase storage, increasing spillway capacity, providing for safe overtopping, breaching the dam, or some combination of the first three choices. Site conditions or high costs frequently make the first two methods infeasible, and functional needs usually make breaching unacceptable. Providing for overtopping protection may be the only reasonable solution. Use of roller-compacted concrete (RCC) for overtopping protection has proven to be an economical and effective way to increase the hydraulic safety of a dam. Of the 30 dams that have RCC overlays, 22 classified as small dams according to the International Committee on Large Dams’ definition of 50 ft or less in height.

ASCE Subject Headings:
Dam safety
Roller-compacted concrete
Wave overtopping