National Dam Inspection Program. Upper Donohoe Dam (now Referred to as) Twin Lakes Number 2 Dam, NDS I.D. PA-00478, PennDER I.D. 65-55), Ohio River Basin, Little Cragtree Creek, Westmoreland County, Pennsylvania. Phase I Inspection Report.

摘要

The Upper Donohoe Dam is an earth embankment approximately 520 feet in length with a maximum height of 34 feet. According to PennDER records, the embankment was constructed with a puddle cutoff wall having a top and base width of 10 feet, a maximum height of approximately 18 feet and length of 500 feet. The depth of excavation for the cutoff wall is reportedly about 15 feet below the original ground surface. Both the upstream and downstream slopes were originally protected by 'stone covered with mortar.' Recently, however, a hard, siliceous limestone riprap was placed on the top 5 to 6 feet of the upstream slope and a brick deck was laid across the entire crest. The facility is served by a rectangular-shaped concrete channel spillway constructed in 1977 and located at the right abutment. The discharge channel is cut in natural ground and rock below the spillway. A 12-inch diameter cast iron pipe passes beneath the center of the embankment and serves as the outlet conduit. The outlet conduit is valved at a valve house located at the downstream toe of the embankment. Upper Donohoe Dam is located on the headwaters of Little Crabtree Creek in Hempfield and Unity Townships, Westmoreland County, Pennsylvania.