Housatonic River Basin, Derby, Connecticut. Lower Ansonia Reservoir Dam (CT 00027). Phase I Inspection Report. National Dam Inspection Program

摘要

The Lower Ansonia Reservoir Dam was built around 1887 and presently impounds a water supply reservoir. It is an earth and masonry embankment with a total length of approximately 423 feet, including a centrally located 20.3 foot long broad-crested masonry spillway and a brick gatehouse. The top of the embankment, at elevation 279.2, is approximately 25 feet wide, 2.2 feet above the spillway crest and 17.8 feet above the streambed at the downstream toe of the dam. With the reservoir level to the top of the dam the dam impounds approximately 94 acre-feet of water. The spillway capacity with the reservoir level to the top of the dam is 210 cfs, which is equivalent to 19% of the routed test flood outflow. Based upon the visual inspection at the site and past performance, the project is judged to be in fair condition. No evidence of instability of the project was observed. However, there are items which require attention, such as sparse riprap in the spillway discharge channel, debris in the channel, maintenance of the downstream slope and top of dam, and possible seepage through the spillway section.