Case Study: Waterbury Hydroelectric Facililty

Waterbury Hydroelectric Facility New Bypass Pipe, Waterbury, VT

Green Mountain Power (Waterbury, VT)


On February 19, 2016 the Federal Energy Regulatory Commission (FERC) issued Green Mountain Power (GMP) a new License to continue operating and maintaining the Waterbury Hydroelectric Project No. 2090. The Order Issuing the new License includes the Vermont Department of Environmental Conservation’s (VDEC) 401 Water Quality Certification (WQC) Conditions, which required GMP to implement a new operation plan that included upgrades to the Project, specifically the design and installation of a new turbine runner and bypass pipe with automated valves. GMP retained the services of Gomez and Sullivan Engineers, D.P.C (GSE) to design and detail the new minimum flow bypass pipe and associated valves and support structures at the Waterbury Hydroelectric Plant. The runner replacement is being done by Norcan Hydraulic Turbine, Inc.

The WQC requires GMP to implement a new operations plan over three stages. In accordance with the WQC, during Stage II operations, GMP shall operate the Project in run-of-river mode within the operating range provided by the automated valve and the new runner (hydraulic capacity 49-391 cfs). The hydraulic capacity of the new automated bypass will be 0 – 250 cfs, per the requirement of VDEC. GSE performed a study that analyzed several pipe sizes and determined that a 60-inch diameter steel pipe would meet the flow and material requirements.

To accommodate the operation requirements set by the new WQC and License, GMP will tee into the existing 79-inch-diameter penstock (exposed portion within the powerhouse basement) with a new 60-inch-diameter bypass pipe and associated valves, joints, and supports. The proposed construction activities for the Bypass Pipe Project include: the removal of a segment of the existing 79-inch penstock; removal of a portion of the main floor, east basement exterior powerhouse wall, and west first floor exterior powerhouse wall, installation of 78-inch and 60-inch butterfly valves, installation of 14-inch and 24-inch fixed cone valves, three reinforced concrete thrusts blocks, and steel access platforms to the fixed cone valves and existing State owned 48-inch bypass pipe.

Construction of the Project began in September 2017 and is scheduled to be completed by April 2018. PC Construction of South Burlington, VT is the Construction Manager for the Project.