Denver Water reports its new 7.598-MW Gross Reservoir hydroelectric project, on South Boulder Creek in Boulder County, Colo., is expected to generate 25,000 megawatt-hours each year.
Denver’s Board of Water Commissioners holds a Federal Energy Regulatory Commission license for the project (No. 2035). The project entered full operation in August 2007.
The new hydro plant uses water impounded by a 340-foot-tall, 1,050-foot-long concrete gravity arch dam built in 1954. The dam forms Gross Reservoir, which stores 41,000 acre-feet of water. The reservoir is a major component of Denver’s municipal water supply system.
Releases from the reservoir are made through low-level outlet works consisting of an intake slide gate, a tunnel, conduits, and a valve house. To supply water to the new powerhouse, which is about 400 feet downstream of the valve house, Denver Water installed a 66-inch-diameter penstock.
The powerhouse features two horizontal Francis turbines manufactured by Alstom Canada, designed for a rated output of 3.799 MW each, and synchronous generators manufactured by General Electric, rated at 4,500 kVa, and associated mechanical and electrical equipment.
Denver Water designed the project and managed construction. Construction costs totaled $14.1 million and included a $10.6 million contract to Western Summit Constructors Inc. of Denver, general contractor.