A Tale of Two Turbines

A pair of behind-the-scenes powerhouses generate consistent, dependable power
By Rodger Nichols

A distant view of the turbine housing at McNary Dam.

Deep inside The Dalles Dam, a turbine— what might be thought of as a 25-ton top—spins at 200 rpm day and night, 24/7/365.

Except for periods of maintenance, it has spun for more than a quarter-century, generating a steady, dependable stream of renewable power for Northern Wasco County PUD.

One hundred miles upriver, an even larger unit inside McNary Dam operates jointly with Klickitat PUD.

The units are there as a result of fish ladders. To attract migrating fish onto a ladder, a channel of water—separate from the dam’s spillways—must provide an encouraging flow at the base of that ladder.

In the late 1980s, it was the vision of former NWCPUD Manager Harold Haake and the PUD board that this separate stream could pass through a turbine on its way to the fish ladder and provide a source of additional electricity. The turbine first spun in 1991.

The Army Corps of Engineers, which operates the dams, did not take advantage of the opportunity due to its small scale. The output of the PUD’s unit is rated at a maximum of 6.5 megawatts, compared to the maximum of 2,100 MW for the dam as a whole.

Derrick Mauritson, chief operator of The Dalles hydro project, says the facility generates a steady 5 MW.

Greg Hendricks, his counterpart at McNary, says the facility there came online in 1997. It’s a larger setup that delivers just more than 10 MW. Half of that goes to Klickitat PUD, which jointly finances the project with Northern Wasco County PUD.

Between the 5 MW generated at The Dalles and an equal amount from their share of the McNary output, the two sources account for about 10% of the energy distributed by NWPUD. Assistant General Manager Kurt Conger says that equals about 80,000 MW hours per year. “The key is they provide renewable energy around the clock, with little variation between winter and summer or day and night,” he says.

The shaft of the turbine at The Dalles Dam.

That base load is what provides stability when mixed with wind or solar. The wind does not always blow and the sun does not always shine, but the river always runs.

When the projects began, the output of power was contracted to other utilities, and the revenues were used to pay off the bonds. Since then, the power has been available locally. With a lower cost than the power bought from the Bonneville Power Association, it helps keep down the cost to local ratepayers.

The units each have 50-year licenses from the Federal Energy Regulatory Commission. The Dalles will be up for renewal in 2041 and McNary in 2047.

Nonelectrical systems are needed to keep the turbines turning. These systems include hydraulics, CO2 fire control, and a compressed nitrogen system that can shut down the system mechanically in the event of an electrical failure. Everything is backed up with multiple redundancies.

But the operation of the two sites is more than just equipment. A five-person crew works standard Monday through Friday hours at both locations. All are on-call around the clock if there are any interruptions or problems. Automatic systems generate text messages and phone calls for any out-of- normal operations.

The Dalles Dam crew, from left, are Nicholas Atchley, Bob McBain, Cherish Southard, Derrick Mauritson, and Nathaniel Brunoe.

There is dedication and camaraderie among the crews.

“This is the best work community I’ve ever had experience with, hands down,” says Cherish Southard, who began as a trainee at The Dalles operation and now works full time. She studied electro-mechanical technology at Columbia Gorge Community College.

That message is echoed by several workers at each site, praising management as supportive and caring while maintaining high standards.

Kurt returns the compliment.

“It’s a real comfort knowing that every day we have a solid, professional crew on the job,” he says.

Two nickels sit on the edge on top of the housing that holds the turbine at The Dalles. One was set there decades ago. A second was added recently after most of the original crew retired, and the new crew wanted a representation of its own.

The turbine is so well balanced that the nickels remain on edge. They are fitting symbols for the PUD itself: sturdy, dependable, and well-balanced.