New York Environmental Protection Bureau of Engineering Design & Construction

Gilboa, New York

The $142 million Schoharie Reservoir Project in Gilboa, New York – which is expected to be complete in the year 2020 – includes the construction of an intake structure at the bottom of Schoharie Reservoir, more than 2,000 feet of subsurface tunnels, and a valve chamber along Schoharie Creek. Once completed, the tunnel and valves will provide New York City’s Department of Environmental Protection with the capability to release water from the reservoir into Schoharie Creek to facilitate dam maintenance, respond to potential emergencies, mitigate flood risk for downstream communities, and enhance downstream habitats for fish and wildlife.

Stiver Engineering was retained by the contractor to provide construction engineering through the following consulting services for the Gilboa Dam Project;  access shaft design (40 ft. diameter x 185 ft. deep, ring beam and liner plate/rock bolt, wire mesh and shotcrete shoring system), cofferdam that extended into the Schoharie River for the construction of the valve chamber downstream of the Gilboa Dam, steel tunnel design from the gate shaft to the bottom of the lake (wet) and from the gate shaft to the valve chamber (dry), pipe brake design, pipe bulkhead design for tunnel exit from the gate shaft and within the tunnel itself, bulkhead and bridge design for walking a crane onto a barge, liner plate shaft design for a shaft that will be lowered from the barge to the lake bottom 150 ft. below and the liner plate shaft leveling system that will be used to level the shaft once it reaches the lake bottom.