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National Program for Inspection of Non-Federal Dams. Highland Lake Dam (CT 00106), Connecticut River Basin, Winchester, Connecticut. Phase I Inspection Report.

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The dam is approximately 450 feet long on the paved roadway running along the axis of the dam which serves as a town street and is approximately 40 feet wide. With a maximum height of approximately 14 feet, the dam is composed of a downstream dry-laid stone masonry wall with an upstream earth fill. The upstream slopes are inclined gently into the lake and are protected by dumped riprap. The two spillways are actually lowered portions of the roadway. The spillways, each 75 feet long, discharge over the downstream masonry wall and onto a dumped riprap splash apron. The low level outlet is a culvert through the dam from 2 low level sluice gates located at the upstream face of the dam. From this outlet, water is routed either to a small generator in the Union Pin Company factory immediately downstream of the dam, or to a discharge channel alongside the factory and back into the stream. Based on the visual inspection at the site and past performance, the dam is judged to be in fair condition overall. No evidence of instability was observed in the dam or its appurtenances, and the condition of the earth dikes was good. Based upon the size Intermediate and hazard classification High of the dam in accordance with Corps of Engineers Guidelines, the test flood will be equivalent to the Probable Maximum Flood PMF. Peak inflow to the lake is 9,500 cubic feet per second cfs peak outflow is 6,000 cfs with a freeboard of 1.0 feet to the top of the project. Based on our hydraulics calculations, the spillway capacity is 8,600 cfs, which is equivalent to 143 of the routed test flood outflow.

Subject Categories:

  • Hydrology, Limnology and Potamology
  • Civil Engineering

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