Bonneville Second Powerhouse Columbia River Washington PDF Download

A second powerhouse at the existing Bonneville Dam project was constructed to take advantage of additional upriver storage provided through treaty agreements with Canada. Hydraulic model studies were accomplished to evaluate hydraulic performance with various powerhouse locations. A new navigation lock is proposed for the project. Although the lock was not studied in this investigation, a primary powerhouse design consideration was that the second powerhouse location must not conflict with the logical location of a new navigation lock. A 1:100-scale model was used to study flow conditions in the forebay and tail-race of the powerhouse and to evaluate the effect of the powerhouse on existing fishway and navigation facilities. Three powerhouse locations were studied in the model; however, the final design consisted of an eight-unit powerhouse located on the north (Washington) shore. Tests indicated that raising the tailrace invert to elevation -10 could not be justified due to excessive power loss which would occur with this condition.