Chelan County Public Utility District in Washington State will invest about $60 million to modernize four turbine-generator units at its 624-MW Rock Island hydro facility.
The board of commissioners made this decision June 20 after reviewing the results of intensive staff analysis, concluding the project “meets the strategic objective of investing in long term assets that provide value to customer-owners.”
Cracks in the turbine blades were discovered in 2015 on one unit that was placed in service in 1931. All attempts to repair the cracks were unsuccessful. Shortly after, cracks were discovered on the other three units. All four units are now out of service.
The benefits of this work are:
- Reliable operation of the units for another 50 years
- An expected 12% rate of return
- More flexibility in hydro operations
- Likely no change in electric rates (under currently forecasted conditions)
Staff recommendations include schedule changes for ongoing modernization of four other units in Powerhouse 1 at Rock Island, on the Columbia River, and hiring 10 people for the workload at Rock Island and 1,300-MW Rocky Reach over the next several years. Six of these positions will provide succession planning for projected retirements, according to a press release.
The board set up the $60 million capital project, put the hiring for the 10 positions in motion, and approved the schedule changes. Next steps are to advertise for bids in September and award the contract in January 2017.
This modernization work, on units B1 through B4, is expected to start in fall 2018 and finish in spring 2020. Similar work on the larger B5 and B8 units will be rescheduled for 2020 to 2022, Chelan County PUD says.
In total, the Rock Island facility contains 19 turbine-generator units, with 11 in the first powerhouse (completed in 1933) and eight in the second powerhouse (completed in 1979).
The PUD also owns the 59-MW Lake Chelan hydro project.