Lake DeForest Dam Bascule Gate Replacement, West Nyack, New York (2013)

United Water New York (UWNY) replaced the two 50 feet long by 5 feet high bascule gates at the Lake DeForest Dam. The existing gates were installed when the dam was built in 1956. Working together in a design-build team with UWNY, Jett Industries, Inc. (a Kiewit Company), Steel-Fab, Inc., Complete Hydraulic Works, Inc., and Hatch Engineering, BS&J provided consulting engineering services for UWNY during the planning, design, fabrication, installation, and testing of the new gates. Work was permitted on only one gate at a time with the other gate remaining in service. A cofferdam of structural panels was constructed in front of the concrete opening upstream of the first gate to be replaced and then reused on the second. Special provisions were made to lift, land, position, and install the gates in the spillway openings under the existing access bridge. Fabrication and installation tolerances for the new gates were tight. The project plan was reviewed and permitted by the New York Department of Environmental Conservation and the US Army Corps of Engineers.