National Program for Inspection of Non-Federal Dams. Indian Orchard (MA 00722), Connecticut River Basin, Springfield/Ludlow, Massachusetts. Phase 1 Inspection Report

摘要

The dam is generally comprised of a 401-foot long, 10 to 28 foot high main spillway, a head gate building, an overflow canal spillway and a canal leading to two 8 foot diameter penstocks used in electrical power generation. There are two inoperable gates located in the main dam. The dam is normally operated with two feet of flashboards above the spillway crest. The visual inspection did not disclose any findings that indicate an immediate unsafe condition. The 1 /2 PMF test flood used will produce an inflow/outflow of 70,830 cfs. The dam is a run-of-the-river type and the spillway crest would be overtopped by about 14 feet. The spillway has a capacity of 29,500 cfs (42 percent of 1/2 PMF outlfow) at elevation 166.6, top of non-overflow section. The non-overflow section is overtopped by about six feet. This flow would not overtop the upstream training walls which are at elevation 174.0. The overall condition of the dam is considered fair due to the lack of adequate draw down capacity. Remedial measures consist of removing vegetation from the downstream face of the dam, further observation of seepage at the right abutment, repair the wooden crest cover, and develop a formal warning system to warn downstream areas in case of an emergency.