National Dam Inspection Program. Ponderosa Pines Dam (NDI ID Number PA- 00304, DER ID Number 64-204), Delaware River Basin, Tributary to West Branch Lackawaxen River, Wayne County, Pennsylvania. Phase I Inspection Report
GEO-TECHNICAL SERVICES INC HARRISBURG PA
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Based on visual inspection, field survey and calculations, Ponderosa Pines Dam is judged to be in poor condition. As the spillway cannot pass the 12 PMF without overtopping at less than 12 PMF would cause failure which would significantly increase hazard to loss of life downstream, the spillway capacity is seriously inadequate and the facility is rated unsafe, nonemergency. Although there is no visible evidence of structural instability, the erosion of the downstream slope below the outlet pipe and the leakage below the toe of the dam are of concern. Should the observed erosion and leakage remain unchecked, it could, in time, affect the structural integrity of the dam. The invert elevation of the outlet pipe is but 2.1 feet below the spillway crest. There are no means to lower the reservoir level below the present level of the pipe inlet in case of emergency. The maintenance of the dam is limited to mowing grass on the crest and a portion of the upstream slope of the embankment. The balance of the dam is poorly maintained.
- Hydrology, Limnology and Potamology
- Civil Engineering