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Expect the Extraordinary.


Cabin Creek Hydroelectric Generating Facility



APTIM was selected by Public Service Company of Colorado (now Xcel Energy) to investigate and assess several potential pumped storage sites in Colorado and select one site for development. Following these efforts, APTIM was given the tasks to engineer, design, manage construction, and start up this 300 MW project, which is located high in the Rocky Mountains, above Georgetown, Colorado (near Silverthorne).  Because of the “total service” commitment, essentially all engineering and support service disciplines were involved: from geotechnical to procurement, to startup and commissioning.   

  • Engineering and design 
  • Environmental studies 
  • Construction management 
  • Startup 

Scope and Deliverables: Our scope of responsibility was to engineer, design, manage construction, and deliver an operational project. Extensive geotechnical and structural engineering was required for the main project facilities, consisting of: a semi-outdoor, reinforced-concrete powerhouse containing two reversible-type pump/turbines and generator/motors; an upper reservoir, formed by a 210-foot-high rockfill dam with a concrete face slab; a lower reservoir formed by an earthfill dam 95 feet high; and a 4,300-foot-long concrete- and steel-lined power tunnel.   The remote site required the development of an access road system over rough and environmentally sensitive terrain. The lower reservoir surface is approximately 10,000 feet, and the upper reservoir is approximately 11,200 feet above sea level. The high altitude and cold climate required extensive studies for ice formation at both reservoirs.  Each reservoir has more than 1,500 acre-foot usable storage, which is sufficient to provide about five hours of continuous operation at a 300,000 kW load. The maximum static head is 1,226 feet, which is the highest of any pumped storage plant now operating in North America. The maximum pumping load (both units) is about 357,000 HP at 1,097 feet. The generator/motors are each rated 166,667 kVA at 0.9 PF, 60°C rise, 13.8 kV, operating at a normal speed of 360 RPM. The rotating parts are designed for a maximum overspeed of 540 RPM. Starting motors rated 14,000 HP each at 360 RPM are used to bring the units up to speed in the pumping phase. 

 The Public Service Company of Colorado received the Edison Award for "an outstanding and successful undertaking, involving courageous and ingenious concept, engineering and construction under severe conditions of altitude, climate and terrain."