National Dam Inspection Program. Lower Dam (NDS I.D. Number PA-697, DER I.D. Number 54-57) Delaware River Basin, Silfis run Schuylkill County, Orwigsburg Water Authority. Phase I Inspection Report

摘要

The assessment of Lower Dam is based upon visual observations made at the time of inspection, review of available records and data, hydraulic and hydrologic computations and past operational performance. Lower Dam is a high hazard-intermediate size dam. The spillway design flood (SDF) is the PMF (Probable Maximum Flood). The exisitng spillway and reservoir are capable of controlling approximately 15% of the PMF. Based on criteria established by the Corps of Engineers, the spillway is termed inadequate. If Lower Dam should fail due to overtopping, the hazard to loss of life and property downstream from the dam would not be significantly increased from that would exist just prior to overtopping. Extensive seepage is exiting through or beneath the dam. In addition, the embankment or foundation materials may be piping due to the excessive seepage. The dam appears to be in poor condition. As a result, the dam is considered an unsafe, nonemergency dam. (Author)