Design of Low-Head Hydropower Plant on a Mountain Stream

Client: Albany Engineering, Albany, New York

WRE engineers model-tested the hydraulic design for the Twinfalls Hydroelectric Power Plant, a 24-megawatt facility on the Snoqualmie River in Washington state. This project is unusual because the facility is entirely underground, with its powerhouse located approximately 325 feet below the surface. Project facilities include:

  • A long, nearly horizontal fish screen along approach channels cut into the mountain rock
  • Transitions from open channels to vertical shafts
  • Horizontal Francis turbines direct-coupled to synchronous generators
WRE designed, built, and calibrated a three-dimensional physical model of the intake to the low-head power plant. WRE engineers used the model to test the intake's hydraulic performance under a variety of flow conditions, and refined the dimensions and configuration of the intake channel through the results of the model tests.