National Dam Inspection Program. Unnamed Tributary to Harmon Creek, (NDI Number PA-01125). PennDER-Number 63-84. SCS Number PA-480. Ohio River Basin. Washington County, Pennsylvania. Phase I Inspection Report,
Abstract
PA 480 was designed by the U.S. Department of Agriculture, Soil Conservation Service (SCS) for floodwater detention. The total length of the dam is 555 feet, including the emergency spillway on the right abutement; the maximum height of the dam is 66 feet. The principal spillway is a drop-inlet structure consisting of a two-stage reinforced concrete riser connected to a 30 inch diameter reinforced concrete outlet pipe. The low-level inlet on the concrete riser is a 9 inch high by 15 inch wide orifice; this inlet maintains the normal pool level. There is 25.1 acre-feet of storage at normal pool level, all of which is reserved for a 50-year accumulation of sediment. Hydraulic/hydrologic evaluations, revealed that the spillway will pass the Probable Maximum Flood (PMF) without overtopping the dam. A spillway design flood (SDF) in the range of the 1/2 Probable Maximum Flood (1/2 PMF) to the PMF is required for PA 480. The 1/2 PMF was selected as the SDF. The spillway is therefore considered to be 'adequate'.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 10, 1980
- Accession Number
- ADA088779
Entities
People
- John A. Dziubek