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News Safety & Reliability April 27, 2022

A historic event at our Jackson Project

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A historic event at our Jackson Project

The largest shutdown in the history of the Henry M. Jackson Hydroelectric Project officially ended the early morning of Friday, April 1, 2022. Throughout the 20-day shutdown, crews worked long hours to perform necessary maintenance and address an unanticipated fiber-optic cable failure in the tunnel.

The Jackson Hydro Project can generate up to 111.8 megawatts of power. Jackson, along with the PUD’s other hydro projects (Woods Creek, Youngs Creek, Calligan Creek and Hancock Creek), provides about 8 percent of our power needs.

“It was a monumental achievement by the crews,” said Scott Spahr, PUD Manager Generations Operations and Engineering. “Shutting down generation at Jackson for this extensive period obviously has a cost. Our crews worked early mornings, late nights and rotating night shifts throughout the shutdown to get this very important work done. Our engineers implemented innovative solutions that kept the project on track. I couldn’t be more grateful for the work that these employees performed.”

A shutdown was needed to perform required scheduled maintenance at the Jackson powerhouse that had been delayed due to the COVID-19 pandemic. To perform the maintenance, the tunnel and pipeline connecting the intake at Spada Lake Reservoir to the powerhouse had to be dewatered, but water still had to be able to flow to the Sultan River.

The valves at the powerhouse must be rebuilt on a regular schedule due to their design. Inside the valve is a brass ring and a rotating stainless-steel ring. The softer brass ring wears out due to friction with the stainless steel. If both rings were made of a hard material, then both would wear out and it would require double the maintenance.

While rebuilding the valves, the crews faced an additional challenge: the company that manufactured the brass rings was no longer in business, and original plans for the rings were no longer accessible. To solve the problem, PUD engineers had to work with a new manufacturer to reverse engineer the rings.

Jackson Hydro Project maintenance March 2022
A shiny new brass ring rests in one of the Jackson Hydro Project valves

“The work that was completed has never been done since the plant was constructed,” said Scott. “Not only was this the longest shutdown that has occurred, our crews also rebuilt more valves (five) than had ever been attempted before during a shutdown. It’s unbelievable the amount of work that was completed in such a short time. It’s a testament to how hard-working and skilled our folks are.”

Timing of the shutdown was chosen because spring runoff had not started in earnest and inflows into the lake are low this time of year. This reduces the risk of water flowing into the spillway, as well as reducing the opportunity cost of shutting down generation.

In addition to rebuilding valves, crews also had to complete unexpected work to remove a communications cable that had come loose from the tunnel wall. Going into the shutdown, crews were aware the cable would need to be repaired but did not anticipate having to remove the four-mile cable from the tunnel.

“When the fiber cable was originally installed, the thought was that by securing it every six feet, it would hold for the length of the tunnel,” said Scott. “What we found is that due to rocks and vibrations caused by the force of the water inside the tunnel, portions of the cable were being rubbed away. If pieces of the fiber cable were to come loose and get caught in the turbines, the negative impact would be tremendous.”

When Scott’s team realized the problem, they reached out to the Telecom team and PUD Operations Superintendent Paul Kiss. In true Team PUD spirit, Paul immediately offered to lend Scott a “small army” to help get the work done without having to extend the Jackson shutdown.

In just two days, two Line Crews and the Generation Crews were able to remove four miles of fiber cable from the tunnel.

“I just can’t express enough appreciation for everyone who worked on this project,” said Scott. “In a short time, we were able to complete critical maintenance work to the valves in the Powerhouse, remove a potentially dangerous hazard from the tunnel, and complete maintenance at the powerhouse substation. Special thanks to our Generation Crews, Major Yard, Substation and our Line Crews who assisted in this historic effort.”

Jackson Hydro Project Turbine March 2022
One of the turbines at the Jackson Hydro Project.
Jackson Hydro Shutdown Project March 2022
PUD CEO/General Manager John Haarlow (right) talks with maintenance crew.