National Dam Inspection Program. Thornes Dam (Inventory Number NY 00793). Housatonic River Basin. Town of Amenia. Dutchess County, New York. Phase I Inspection Report,
Abstract
Hydrologic and hydraulic analysis indicates that maximum spillway discharge capacity is only about 6% of the PMF peak outflow. The 1/2 PMF would overtop the stone masonry dam. Structural stability analysis, as well as visual observation, indicates that overtopping due to 1/2 PMF would probably cause failure of the dam. Therefore, in accordance with Corps of Engineers' screening criteria for review of spillway adequacy, the spillway is considered 'seriously inadequate' and the dam is assessed as 'unsafe, non-emergency'. The classification of 'unsafe' applied to a dam because of a seriously inadequate spillway is not meant to connote the same degree of emergency as would be associated with an 'unsafe' classification applied for a structural deficiency. It does mean that there appears to be a serious deficiency in spillway capacity and if a severe storm were to occur, overtopping and failure of the dam could take place, significantly increasing the hazard to loss of life downstream of the dam. Therefore, it is recommended that within 3 months after receipt of this report by the Owner, a detailed hydrologic and hydraulic analysis be started to better assess spillway capacity. Within 18 months after receipt of this report by the Owner, any appropriate remedical work should be completed. In the meantime, the Owner should immediately institute a program to visually inspect the dam and its appurtenances at least once a month. Also, within 3 months after receipt of this report the Owner should complete development of a surveillance program for use during periods of heavy runoff and of an emergency action plan out-lining action to be taken to minimize the downstream effects of an emergency, together with an effective warning system.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1981
- Accession Number
- ADA105963
Entities
People
- Kenneth J. Male
- W. M. Smith Jr