National Dam Inspection Program. Upper Ansonia Reservoir Dam (CT 00029). Housatonic River Basin, Derby, Connecticut. Phase I Inspection Report

摘要

The Main Dam is a masonry gravity structure with a total length of approximately 345 feet, including a 20.5 foot long spillway and a masonry intake structure. The top of the masonry dam, at elevation 309.7 (NGVD), is 2.7 feet above the spillway crest, 20.8 feet above the streambed at the downstream toe of the dam, and varies in width from 3 to 4.5 feet. A bedrock outcrop separates a 200 foot long masonry and earth dike from the left end of the Main Dam. The dike has a top elevation of 309.5 and is approximately 7 feet high. Approximately 700 feet left of the Main Dam and separated from the dike by a small knoll is the East Dam, which consists of a masonry gravity upstream wall and a downstream embankment. The East Dam has a total length of approximately 423 feet, consisting of two sections separated by a low bedrock outcrop which rises to within 5 feet of the top of the dam. The left section is 227 feet in length and 16.2 feet in height and the right section is 196 feet in length and 11 feet in height. The East Dam has a top elevation of 310.0, a top width of 4 to 4.8 feet and does not have a spillway. With the reservoir level to the top of the project, the reservoir impounds approximately 310 acre-feet of water. The spillway capacity with the reservoir level to the lowest point along the top of the dike is 240 cfs, which is equivalent to 28% of the routed test flood outflow.