Early delivery

EPHRATA — A project to reinforce an embankment at Priest Rapids Dam should be completed by the end of this month, about a year ahead of schedule.

“We’re in the final push of that project,” said Dale Campbell, senior manager of power production for the Grant County PUD. “If you haven’t taken a tour, you don’t have much time left. It’s going to be done (by) the middle of August.”

Campbell updated GCPUD commissioners at the July 27 meeting.

The right embankment, the Yakima County side of the Columbia River, was reinforced with a concrete buttress to address an unlikely — but possible — problem. Prior to the reinforcement, the bank could have crumbled in the event of a big earthquake, magnitude 6 or greater on the Richter scale.

In the case of a big earthquake that ground could’ve gotten unstable, Campbell said in an earlier interview. If it did, the damaged embankment could’ve destabilized the Yakima County end of the dam.

The bank was excavated and the dirt was replaced with the new concrete dam.

“We’re drilling holes and we’re pouring concrete in that new concrete dam and the old embankment,” Campbell said.

“We’re really through all of the technical challenges, and we’re nearing the end of this project,” he added.

With the embankment work completed, PUD officials will be restarting work on a project to reinforce spillway pillars at Priest Rapids.

“This project actually was initiated after Wanapum (Dam) fractured,” Campbell said.

Wanapum Dam had a crack in one of its spillways and a damaged spillway support pillar, also known as a monolith. The damage was discovered in 2014, and repaired in 2014-15.

The solution was to reinforce the monolith with steel cables anchored in the bedrock of the riverbed. Holes were drilled in each spillway support, the cables anchored and stretched tight, and the holes filled with concrete.

In light of the repairs needed at Wanapum, PUD officials started evaluating Priest Rapids Dam, and test drilling in 2018 showed water leaking into some of the spillway monoliths. Other projects, including the bank reinforcement, took priority, Campbell said, but with its completion, the spillway reinforcement was restarted.

The reinforcements will be similar to Wanapum Dam, but Priest Rapids Dam needs fewer anchors than Wanapum, wrote PUD Public Affairs Officer Christine Pratt in a press release. The cost for the project is estimated at $38 to $45 million, she wrote.

Utility district officials will apply for a $5 million federal grant to help pay for the project. If the grant is awarded, the PUD would have three years to complete the project. Pratt wrote that it’s expected to take about 18 months once it starts.

Cheryl Schweizer may be reached via email at cschweizer@columbiabasinherald.com.