A unique hydrocombine provides multiple benefits at Wells Dam

Wells Hydroelectric - Generator Rebuild and Unit Refurbishment

The 840-MW Wells Hydroelectric Project is a unique hydroelectric project on the Columbia River in Washington State. How is it unique? Wells features a hydrocombine design—a facility that integrates a 10-unit powerhouse, spillways, and substation into a single structure. This design is particularly advantageous in narrow river valleys, which is the case for Wells Dam.

We provided comprehensive program management, engineering, and construction management services for the major dam overhaul. In the new hydrocombine, generating unit bays are straddled with alternating spillway bays, which requires generators to be in silos to make room for the spillway gates.

The supporting systems are set on a transverse gallery below the spillway sill and call for a compact structure. But, it also has two major advantages. Firstly, the design decreases the mortality rate of downstream passing fish, plus, the length of the hydrocombine is shorter than the traditional powerhouse and spillway. The new design effectively provides a lower mortality rate for juvenile fish than that of traditional projects and the length of the hydrocombine is some 60% of the aggregate length of traditional powerhouse and spillway.