National Program for Inspection of Non-Federal Dams. Pataguanset Lake Dam (CT 00159), Connecticut Coastal Basin, East Lyme, Connecticut. Phase I Inspection Program

摘要

Pataguanset Lake Dam is a 210 foot long earthfill and stone masonry structure. The left half of the dam is an earth embankment with a 10 foot crest width and a crest elevation of 68.0 NGVD. The center section of the dam is an earthfill emergency spillway with sheet piling on the upstream face and a 20 foot wide concrete paved crest. The crest elevation of this section is 65.2 NGVD. The spillway is a broadcrested weir, 15 feet long, with a crest elevation 62.7 NGVD. The outlet consists of a 6 foot wide rectangular concrete channel with stop log controls and an invert of 60.2 NGVD. The maximum height of the dam is 11.6 feet. The dam has a maximum impoundment capacity of 950 acre-feet at the top of dam elevation of 68.0 NGVD and used for recreation. The test flood has a routed outflow discharge equal to 1,800 CFS and would overtop the dam by 0.3 feet. The maximum spillway outlet, and emergency spillway capacity is equal to 1,580 CFS which represents 88% of the test flood outflow. Based on a visual inspection at the site, the dam is considered to be in FAIR condition. It is recommended that the left training wall of the outlet channel be repaired or replaced immediately upon receipt of this report.