National Program for Inspection of Non-Federal Dams. New Canaan Reservoir Dam (CT 00055), Southwestern Coastal Basin, New Canaan, Connecticut. Phase I Inspection Report

摘要

The dam at New Canaan Reservoir is an earth embankment approximately 445 feet long, 37 feet high and having a top width of 21 feet. Built originally about 1898 with subsequent modification from 1929 to 1942, this dam impounds water used by New Canaan, Connecticut. The New Canaan Water Company presently owns and operates the dam including its water works facilities. Based on the visual inspection and past operational performance, the dam is judged to be in fair condition. Seepage was noted on the downstream face. The emergency outlet works have not been operated in some time. The two service bridges were found to be in need of repair. Trees were recently cut on the downstream face and the slope is in an unvegetated state. This dam is classified as small in size and a high hazard potential structure in accordance with the recommended guidelines established by the Corps of Engineers. The test flood for this dam is the Probable Maximum Flood (PMF). The test flood has an outflow discharge equal to 1820 cfs and will overtop the dam by 1.1 feet in a stillwater condition. The maximum outflow capacity of the spillway under stillwater conditions is 240 cfs, which is approximately 13 percent of the test flood. It is recommended that the following items be studied further: The location, condition, and operability of various outlet works; downstream seepage; the composition and adequacy of the dam embankment; the stumps from recently cut trees on the downstream face of the dam; and the deteriorated condition of the service bridge to the gate house.