National Program for Inspection of Non-Federal Dams. Lower Ross Pond Dam (CT 00175), Thames River Basin, Killingly, Connecticut. Phase I Inspection Report

摘要

The dam at Lower Ross Pond is approximately 600 ft. long, 6 feet high, and is an earth embankment with a downstream stone masonry-concrete capped face. The earth fill section varies in width from 3 to 10 feet along the upstream face and has varying slopes into the pool. The downstream face of the dam is vertical. There are two uncontrolled overflow spillways about 128 feet apart through the dam. The easterly spillway is a masonry and concrete capped weir 12.5 feet long. Short masonry training walls lead into the reservoir pool and channel overflows to the weir section. The downstream channel is Half Hill Brook which meanders through wooded terrain. The westerly spillway weir is 13 feet wide and also has training walls leading into the pond. The easterly spillway crest is approximately 2 feet below the westerly spillway crest. There is no outlet works for the dam. The spillway capacity is hydraulically inadequate to pass the 'test flood' (100-year) and this flow would overtop the by approximately 0.40 feet assuming the overflow length of the dam was equal to 100 feet. The inflow and routed outflow discharge value for this test flood are 296 CFS and 250 CFS, respectively. The maximum outflow capacity of the spillway without overtopping the dam is 142 CFS which is 57 percent of the routed test flood outflow.