National Dam Inspection Program. Lake Sheridan Dam (NDS-ID Number PA-744 DER-ID Number 66-45), Susquehanna River Basin, Lake Sheridan Outlet, Wyoming County, Phase I Inspection Report

摘要

Lake Sheridan Dam is a rubble masonary and concrete gravity dam. The dam is 89 feet long and 9 feet high. The intercore of the dam consists of the original rubble masonry construction. The concrete portion of the dam was added during the 1966 modifications. The dam consists of an overflow and a non-overflow section. The overflow section of the dam serves as the normal spillway for the reservoir. The crest length of the spillway is 40 feet. A reservoir drain valve is located on the upstream end of the right non-overflow section. In general, the dam appears to be in good condition. The spillway design flood for this dam is the 1/2 PMF to PMF. The spillway design flood was selected as the PMF (probable maximum flood) based on the downstream potential for loss of life and property damage. The spillway is capable of controlling only 2% of the PMF. Based on criteria established by the Corps of Engineers, the spillway is termed inadequate. Since Lake Sheridan Dam's non-overflow section consists of a concrete section over rubble masonry, the non-overflow section should be capable of safely controlling a partial overflow. However, the amount of overtopping that can be safely controlled is unknown. In this case the amount of overtopping is directly related to the structural stability of the dam. No visible seepage or other obvious deficiencies affecting the stability of the dam were noted during the inspection.