Analysis of Fish Screen Failure and Court Testimony on Causes of Failure

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. The screens on the tunnel intakes failed soon after project commissioning, and as a result, the plant’s designers were sued by the project owner.

WRE’s Principal Engineer was retained by the defense counsel for his detailed knowledge of the project, having participated in its design. As a witness for the defense, he was able to demonstrate that changes introduced by the project owner and not the original design were responsible for the screen failure. The original design called for the cleaning of the screens with automated mechanical rakes. The owner decided not to install the rakes and instead installed an air cleaning system, which caused the screens to fail the first day it was placed in operation (the units had been operating successfully for several months without the rack cleaners).

The court found in favor of the defendants.