National Dam Safety Program. Upper and Lower Dams (NDI Number PA 00389, PennDER Number 20-55, SCS Numbers PA 487A and B), Ohio River Basin, Crooked Creek, Crawford County, Pennsylvania. Phase I Inspection Report

摘要

Upper and Lower Dams consist of two dams in series designed by the U.S. Department of Agriculture, Soil Conservation Service (SCS) for floodwater detention and waterfowl habitat enhancement. Lower Dam is the primary structure upon which this report focuses because the majority of Upper Dam becomes inundated by backwater from Lower Dam before the emergency spillways at Lower Dam are activated. Hydraulic/hydrologic evaluations revealed that the spillways will pass the Probable Maximum Flood (PMF) without overtopping Lower Dam. A spillway design flood (SDF) equal to the PMF is required for Lower Dam. Therefore, the spillways are considered 'adequate.' The inspection revealed only one deficiency which should be corrected immediately, namely, the repair of the chipped concrete on the impact basin of Upper Dam.