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National Dam Safety Program. Lake Mahopac Dam (Inventory Number NY 1329) Lower Hudson River Basin, Putnam County, New york. Phase I Inspection Report,

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The examination of documents and the visual inspection of Lake Mahopac Dam and its appurtenant structures did not reveal conditions which constitute an immediate hazard to human life and property. Using Corps of Engineers screening criteria, it has been determined that the dam would be overtopped for all storms exceeding approximately 56 percent of Probable Maximum Flood PMF. The maximum spillway discharge capacity is 7.9 percent of the PMF peak outflow. The spillway is, therefore, adjudged as inadequate. The following remedial measures should be performed within 12 months from notification 1 Missing portions of the upstream stone masonry wall should be repaired. 2 Brush and shrubbery should be removed from the embankment, spillway-reservoir drain structure and downstream channel. Provide a program of periodic cutting and or mowing of the dam surfaces, spillway-reservoir drain structure and the downstream channel. 3 The collected debris at the spillway-reservoir drain structure and in the downstream channel should be removed and hauled away from the dam. 4 A program of periodic inspections and maintenance of the dam and appurtenances should be provided, including yearly operation and lubrication of the reservoir drain and its control facilities. This information should be documented for future reference. 5 An emergency action plan for the project should be developed.

Subject Categories:

  • Hydrology, Limnology and Potamology
  • Civil Engineering

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