Connecticut Coastal Basin, Darien - Norwalk, Connecticut. Chasmars Pond Dam (CT 00059). Phase I Inspection Report. National Dam Inspection Program.
CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV
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The Chasmars Pond Dam, completed in 1900, is a 92-foot-long, 11-foot-high masonry overflow structure. The dam impounds the Fivemile River on the Norwalk-Darien, Connecticut, border approximately 35 feet upstream from a 25.8-foot-high and 18.6-foot-wide horseshoe-shaped masonry railroad culvert. Based on the visual inspection and past performance, the dam is judged to be in fair condition. No evidence of instability or bulging were observed, but there were signs of seepage at the base of the dam and wing wall near the right abutment. Much of the mortar between the stone blocks on the exposed downstream face was missing however, these joints did not appear to be the source of any seepage. The test flood outflow is approximately 5,040 cfs and the capacity of the spillway, with the water surface at the top of the dam, is 470 cfs or 9 percent of the routed test flood outflow. At discharges in excess of 1,600 cfs control passes from the dam to the railroad culvert. As a result, during the test flood the spillway dam becomes a submerged weir due to the headwater effects created by the culvert and the dam will be overtopped by approximately 10.5 feet.
- Hydrology, Limnology and Potamology
- Civil Engineering