National Program for Inspection of Non-Federal Dams. Crystal Lake Dam (CT00097), Lower Housatonic River Basin, Torrington, Connecticut. Phase I Inspection Report

摘要

Crystal Lake Dam is an earthen embankment structure with a maximum height of 36 feet and a length of 230 feet. The centrally located stone masonry spillway is 50 feet wide. The broad crested weir has a series of stone steps which compromise the downstream face. The outlet works consist of an 18 inch diameter conduit which passes through the dam to the left of the spillway structure. Crystal Lake is used for passive recreation. The lake has a maximum storage volume of 63 acre-feet and the size classification is thus small. A breath of the dam could effect several homes and commercial establishments, along with Connecticut Route 4 and 272 which are in the probable impact area. With the possibility of some loss of life and the probability of excessive economic losses, the dam has been classified as having a high hazard potential. The dam is judged to be in generally fair condition. The crest of the dam has a slight undulation and is subjected to vehicular traffic. Some erosion of the downstream slope has occurred. No embankment or downstream seepage was noted. Large trees are growing along the downstream slope of the dam. The stone masonry spillway is in good condition. The capacity of the spillway is inadequate to pass the one-half PMF test flow outflow (3790 CFS) without overtopping the dam. The test flood would overtop the dam by about 1.6 feet. The spillway can pass about 51 percent of the test flood outflow without overtopping the dam.