Chelan County Public Utility District’s Board of Commissioners has authorized staff to move forward with updated plans for modernizing Units B1-B4 at its 624-MW Rock Island Dam hydro facility.
Andritz Hydro was the lowest bidder to complete the work and offered an alternate option that would take three units down at one time, at a lower cost and would end up begin completed six months earlier than previous estimates, Chelan PUD says.
“By acting today, we can take advantage of a $1.24 million discount and the four Rock Island operating units … could be returned to service six months earlier than we thought if all safety concerns related to acceleration can be met,” said Chelan PUD General Manager Steve Wright.
This early completion would mean the units are available prior to the PUD’s “check in” for its Habitat Conservation Plan, Chelan PUD says. Under the proposed schedule, Chelan PUD gets greater flexibility to address any future unplanned outages at Rock Island as well.
Rock Island Dam was the first dam on the Columbia River and is about 12 miles downstream from Wenatchee, Wash. It impounds water for two powerhouses, one that was completed in 1933 with 11 turbine-generator units and the second completed in 1979 with eight turbine-generator units.
Chelan PUD announced in June that it would invest about $60 million to modernize these four units, concluding the project “meets the strategic objective of investing in long term assets that provide value to customer-owners.” All four of these units are currently out of service after cracks were discovered in the turbine blades and all attempts to repair them were unsuccessful.
This work is expected to provide reliable operation of the units for another 50 years and provide an expected 12% rate of return.
Chelan PUD owns three hydroelectric projects, including 1,300-MW Rocky Reach and 59-MW Lake Chelan.