EPHRATA — Grant County PUD commissioners voted to approve $1.64 million in changes to the contracts for upgrading the turbines at Priest Rapids Dam. Commissioners approved the change order at the regular commission meeting Tuesday.

Construction on the 10-year project is scheduled to begin in August, with work on one turbine-generator unit per year. In February commissioners awarded an $88.7 million contract to Voith Hydro as the construction lead.

Utility district engineers working on the project hoped to refurbish some of the parts, said engineer Molly Hill, but in some cases that might not be possible. As part of the project Voith Hydro officials conducted an analysis of the turbines, and in some cases they recommended replacing parts.

The parts were expensive enough that the PUD asked for a second opinion, and in the case of the outer head covers, the second analysis also recommended replacement, Hill said. The outer head covers, as their name implies, cover the turbines.

In answer to a question from commissioner Larry Schaapman, engineer Brad Strickland said replacing one part of the head cover means replacing it all. Because of engineering and design specifications, the first one will be more expensive, Strickland said. In addition, the first one must be completed by December to keep the project on schedule, he went on, which makes it more expensive. The cost is estimated at $1.1 million. It might be necessary to replace the head covers on all 10 generators, Hill said; the remaining nine would cost about $8 million. But whether or not replacements for the other nine will be necessary is still to be determined, she added.

If new head covers are needed on the other generators, Hill said, the engineering staff is suggesting a separate contract for the entire project.

Commissioners also approved spending $287,000 to buy parts for the moveable plates that allow water to flow through the turbines, called wicket gates. The plan is to reuse those pieces, but they have to be removed and that could damage them, Hill said, so some spare parts are necessary in the opinion of the engineers.

Other spare parts were included in the request at a cost of $405,000. The parts go into a section of the turbine called the packing box and PUD employees said keeping spare parts would make maintenance more efficient.