About a year after Centralia City Light built the Cooks Hill Substation in 2008, a power line feeding Providence Centralia Hospital from the B Street Substation had failed. That cable remained stuck in conduit for days under Interstate 5, circumstances of which would have been disastrous to the hospital if it weren’t for the newly energized substation nearby.
Now, with over $24 million in capital improvement projects slated for the next four years, Centralia City Light is hoping it can avoid more unforeseen malfunctions while it replaces an aging electrical system.
“We’re worried about future bullets,” said Centralia City Light Director Ed Williams.
Many of those bullets can be dodged with a rebuild of the B Street Substation, City Light’s “Achilles’ heel” and one of its most expensive oncoming projects at $4.2 million. Currently, an on-site power failure there can knock out half of Centralia’s electricity.
Ideally, City Light would urbanize its electrical grid with a circulatory system that prevents power outages. But that would cost $40 million and the city balked at the utility’s proposal estimate.
“We didn’t want to raise our rates very much,” Centralia Mayor Harlan Thompson said.
Instead, the city approved capital improvement projects to the tune of about $24 million, which covers the utility’s most pressing needs. City Light customers can expect to reimburse those improvements with an additional 5.5 percent tacked on their utility bills through 2012, starting in late July.
The rate increase will also cover an additional 7.5 percent the Bonneville Power Administration began charging City Light and other utilities for electricity last October. Although City Light has a diversion dam and hydropower facility on the Nisqually River near Yelm, it relies on BPA for about 75 percent of its power.
Built in 1929, the Yelm facilities had supplied Centralia with all of its power through the 1950s.
“It’s almost like a museum, in some respects,” Williams said.
In fact, half of the power poles that carry transmission lines for 27 miles from the Yelm hydropower facility to B Street are the original knotty cedars that had been dug into place before the Great Depression. And they are in need of replacing. But a new transmission line will cost an estimated $6 million to $10 million, and that didn’t make it into capital improvements.
This summer City Light will shut down the hydropower plant for four to six weeks for upgrades to its switchyard and switching gear, which date back to 1965, for improving security around the perimeter, and buffering an earthen tailrace barrier with tree roots and boulders where erosion has claimed some river bank, to the tune of about $2 million.
The plant usually undergoes a temporary maintenance shutdown each September when the Nisqually River draws down to a low flow.
With three turbines, the plant is capable of producing 12 megawatts of electricity. Two of those turbines are part of the original design, while the third, which is capable of producing 6 megawatts, came online in 1955 and roughly doubled the powerhouse of the Yelm hydropower facility.
“It’s the best kept secret in all of City Light,” plant generation manager Orion Albro said.
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Adam Pearson: (360) 807-8208
