The Federal Energy Regulatory Commission on April 9 gave notice of a February application from the Cascade Water Alliance for a preliminary permit to study the feasibility of the White River-Lake Tapps Reservoir Ancillary Hydroelectric Project, which would add 10 MW of capacity to an existing facility and revive a shut 27-MW generator at the site.
The project is to be located on the White River in Pierce County, Washington. The sole purpose of a preliminary permit, if issued, is to grant the permit holder priority to file a license application during the permit term.
The project would consist of new and existing facilities including: a 352-foot-long, 4-foot-high rock-filled, timber crib barrier structure with 7-foot-high flashboards; headworks consisting of two slide gates; a 7.75-mile-long flowline from the headworks to Lake Tapps which consists of a concrete flume, five settling basins, a concrete canal, an unlined earthen canal, and two concrete pipes; a valve house with a new 5-MW turbine/generating unit; a new transmission line from the valve house to a new substation near the valve house; Lake Tapps with a surface area of 2,740 acres and storage capacity of 46,700 acre-feet at elevation 542.5 feet above mean sea level; an intake structure on Lake Tapps; a 225-foot-long, 85-foot-wide, 55-foot-high concrete-framed powerhouse containing an existing 27-MW Francis generating unit and a new 5-MW unit with a total installed capacity of 32 MW; and a new 4,181-foot-long, 115-kV transmission line connecting to a nearby substation. The estimated annual generation of the project would be 50 gigawatt-hours.
The applicant contact is: Chuck Clark, Chief Executive Officer, Cascade Water Alliance, 520 112th Avenue NE, Suite 400, Bellevue, Washington 98004; phone: (425) 453-0930.
The deadline for filing comments, motions to intervene, competing applications (without notices of intent), or notices of intent to file competing applications is 60 days from the issuance of this April 9 notice.
The existing facilities were built in 1911 and operated for hydroelectric power generation until January 2004. After power generation ceased in 2004, the prior owner of the facilities continued water diversion for recreational purposes on Lake Tapps. In 2009, the Cascade Water Alliance, a municipal entity, purchased Lake Tapps and all facilities associated with the project as a source of municipal water supply. In 2010, it acquired three new water right permits in connection with the Lake Tapps Facilities for municipal water supply purposes and modified an existing water right for hydropower and other beneficial uses including recreational reservoir levels and fish and wildlife habitat protection and enhancement. The proposed hydropower project would be ancillary to the present and future use of the Lake Tapps Facilities for municipal water supply purposes.
In the Lower Conveyance, Cascade would utilize the powerhouse by returning the existing turbine, generator, and transmission facilities to service, providing the potential for up to 27 MW of generating capacity via one of the four existing penstocks. In a second penstock, an in-line turbine generator on the order of 5 MW would be installed capable of operating over a range of lower discharge volumes. This second generator could be operated in parallel with or in lieu of the existing generator. Discharges from Lake Tapps would be conveyed through these generators as a means of energy dissipation and power recovery.
Along the Upper Conveyance, Cascade would install an in-line turbine generator with a capacity of roughly 5 MW at an existing valve house located on one of two parallel tunnels. River diversions into Lake Tapps conveyed through this Upper Conveyance generator would discharge energy by recovering power.