National Dam Inspection Program. Alder Marsh Dam (NDI ID Number PA-00153, DER ID Number 64-150), Delaware River Basin, Alder Marsh Brook, Wayne County, Pennsylvania. Phase I Inspection Report.
GANNETT FLEMING CORDDRY AND CARPENTER INC HARRISBURG PA
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Alder Marsh Dam is a zoned-earthfill structure approximately 250 feet long including both spillways and 10 feet high. The impervious core of the dam has a base width equal to one-third of the total base width of the embankment and extends to the top of the embankment where it has a width of four feet. The principal spillway consists of a rectangular channel, with concrete side walls and a grouted stone floor, constructed through the left end of the dam. A double row of stoplogs near the center of the channel are used to control the reservoir pool elevation. Based on available records, visual inspection, calculations, and past operational performance, Alder Marsh Dam is judged to be in good condition. Considering the size and hazard classification of the dam, the recommended Spillway Design Flood SDF varies between the 100-year flood and the 12 Probable Maximum Flood PMF. The 12 PMF was, in this case, selected as the SDF. The existing spillway will pass approximately 44 percent of the PMF before overtopping of the dam occurs and is, accordingly, rated as inadequate. If the emergency spillway channel were widened to its design width and the crest lowered to its design elevation, the spillway would pass about 70 percent of the PMF. The spillway would then be rated as adequate.
- Hydrology, Limnology and Potamology
- Civil Engineering