National Program for Inspection of Non-Federal Dams. Abbott Dam (CT 00582), Thames River Basin, Pomfret, Connecticut. Phase I Inspection Report

摘要

Abbott Dam consists of an earth embankment 440 feet long, 33.5 feet high, with a crest width of 14 feet. Both the upstream and downstream slopes are grass-covered but otherwise unprotected. The facility has two spillways. The normal spillway consists of a vertical drop inlet structure which connects with the outlet conduit through the dam embankment. The emergency spillway is a trapezoidal channel, 40 feet wide at the base, which excavated in natural ground. The facility has one gate valve for the purpose of lowering the pond level, however, this valve was inoperable at the time of the inspection. The assessment of the facility is based on the visual inspection, since only limited engineering, operational, and maintenance data are available. The dam is judged to be in FAIR condition with several maintenance items that require attention to insure the long term performance of the items that require attention to insure the long term performance of the structure. These items include: erosion of embankment due to wash and turbulence at the outlet, seepage from the abutment areas, vibration of the outlet conduit caused by the turbulent outflow from the conduit and the inoperable gate valve. The dam has sufficient outflow capacity to prevent overtopping of the embankment by the test flood. The combined discharge capacity of both the drop inlet spillway and the emergency spillway is 1192 CFS which represents 277 percent of the test flood outflow. The capacity of the emergency spillway represents approximately 95 percent of the total discharge capacity of the dam.