EPHRATA — A decades-long project to upgrade turbines and generator units for both dams owned and operated by the Grant County PUD is three-quarters complete. Upgrades to the fifth of 10 generator-turbine combinations at Priest Rapids Dam are done.

Dale Campbell, senior manager of power production, said crews finished more than 30 days ahead of schedule, and have moved on to the next one.

“That unit is now mostly disassembled and it’s good we chose that unit,” Campbell said. “It was in really rough shape.”

Some pieces of the turbine were showing signs of wear; one had cracks that showed it was in danger of failing, he said. 

“(Upgrade work) is on track,” he said. “We got a little behind in the first month or so, but we’ve been able to make up time and we’re back on track.”

Work on Priest Rapids turbines and generators began in 2016, with the entire project scheduled for completion in 2030. Each unit takes about 14 months to complete, according to earlier interviews with PUD officials.

The work at Priest Rapids began after a similar project at Wanapum Dam, which started in 2004. The goal was to take advantage of upgraded technology and improve efficiency, and power production as a result, at both dams.

When it’s done the project will cost more than $1 billion, according to earlier estimates. 

Utility district officials set targets for various functions of dam operation, one of which measures how often equipment is working and not under repair. The power supply division met its target for all but two months of the year. Ben Pearson, senior manager of hydro generation, said the disruption in October and December was a transformer part. The problem also prompted a further review of those parts throughout the transmission system. 

“We discovered it during maintenance, and we decided to extend that outage to replace the (part),” he said. 

The part, a bushing, wasn’t broken, but it could’ve broken, and after finding one that was failing, PUD employees went through the records and found another that was showing signs of breaking down. If they failed, there could’ve been serious consequences, Pearson said.

“We didn’t want to risk a catastrophic failure — any explosion, fire, potentially,” he said.

The two potential failures prompted further review, Pearson said, since the bushings are about 10 years old. The parts also will be subjected to more scrutiny during maintenance.

“We’re sending at least one of these bushings back to a third-party vendor to do some forensics diagnostics,” he said. “We’re trying to figure out if maybe this is a problem with this type of bushing, this manufacturer of bushing — these are not expected to fail in 10 years of use. We’ve had three or four of these fail since we put these in service. These are fairly new transformers.”

Cheryl Schweizer can be reached via email at [email protected].