Costs going up at Priest Rapid Dam

WANAPUM DAM - Upgrading the turbines at Priest Rapids Dam will cost an additional $22,698,254. The new contract price for the entire turbine project will be $87,062,072.

Grant County PUD commissioners received an update on the project during their regular meeting on July 18 at Wanapum Dam. The commissioners awarded the initial contract for the project to Voith Hydro in July 2014.

When the contract was being prepared and awarded, PUD engineers said they hoped to refurbish and reuse some of the parts. But some of those parts will have to be replaced, said project engineer Molly Weisbeck.

The original plan was to reuse the pieces - wicket gates - that control water flow into the turbines. But Weisbeck said the PUD tested the wicket gates and discovered the material in them didn't meet the engineering standards for durability in cold weather conditions.

As a result, the contractor ran some computer models and projected the wicket gates were worn out and could break, Weisbeck said. Commissioner Larry Schaapman asked what the consequences would be if the wicket gate broke, although he was already pretty sure he knew the answer, he said.

Weisbeck said a broken wicket gate probably would damage the turbine, at a minimum. Brad Strickler, another engineer on the project, said a broken wicket gate on a Susquehanna River dam led to the damage to multiple turbines. In the worst case a broken wicket gate could contribute to flooding in the powerhouse, Strickler said.

In any scenario, it would take months to fix the broken gate and turbine, said PUD assistant manager Chuck Berrie. Depending on the damage, it could take a year or more to repair, Strickler said.

Pre-construction analysis also revealed modifications will be required to the turbine shafts, Weisbeck said. Utility district engineers also recommended modifications to the opening and closing mechanisms on the wicket gates, and installing a lighter access hatch at the bottom of the turbine shaft.

New wicket gates for all 10 turbines were projected to cost $16,725,749. The turbine shaft modifications were estimated at $5,717,189. The modifications to the wicket gate mechanisms was estimated at $158,010, and the new access hatch would cost an estimated $97,306.

Commissioner Bob Bernd said he would vote for the additional money, because the problem had to be fixed. He asked why new wicket gates weren't included in the original contract, and if the PUD's own engineers could've found the problem earlier.

Strickler said the PUD employees who wrote the project specifications were trying to reuse and refurbish as many existing parts as possible. At the time PUD employees said the costs might change after further analysis, said PUD general manager Tony Webb.

Voith Hydro had the equipment to do the computer modeling when the PUD didn't, Strickler said. The results of Voith's analysis were reviewed by outside engineers, said Stuart Hammond, part of the PUD engineering team.

Bernd asked if PUD staff had considered resubmitting the project for new bids. Strickler said they had, but adding the change to the existing contract was the most cost-effective way.

Commissioner Dale Walker asked if the new setup would increase production efficiency, but Weisbeck said it won't make any difference either way.

Weisbeck said more changes may be coming. The contractor has recommended reinforcement to some parts, making maintenance easier on others, and replacing others. She estimated the additional cost would be less than $1 million per turbine.

The turbine project is scheduled to begin in August 2016.