Wire brushes in hand, a Bonneville Power Administration crew used handcarts attached to power lines to whisk up and down the lines in Maltby over the weekend, scrubbing off moss and other debris that have built up over the years.
The high-wire cleaning act was designed to squelch the noise given off by the power lines, which nearby residents say has become unbearably noisy since the amount of power the lines carry was doubled to 500 kilovolts in September.
The crew tested its low-tech cleaning technique on a section between two of the noisiest towers, or about a fifth of a mile. The entire line is about 13 miles long.
Did it work?
"I don’t know yet," said Dennis Sjoquist, BPA’s regional manager for the Puget Sound area. "It appears there has been some reduction, yet I just can’t say definitively whether it corrected the problem."
Decibel levels will have to be tested in all kinds of weather, including when the lines are dry, when they should be quiet if they are working properly.
If tests show the cleaning works, BPA will have to decide if it’s feasible to clean the entire line, and also if it can find a more efficient, less labor-intensive way to do it.
The president of a grass-roots group trying to force BPA to do something about the noise worries that the cost will be too high.
"We’re thrilled by what they’re doing," said Dulane Crist, president of SoundDown, a 140-family neighborhood group that formed after the power lines started buzzing.
"I’m just petrified that they’re going to reach a limit and say, ‘I’m sorry, we can’t do any more,’ " she added. "We definitely feel like we’re at their mercy, and that’s not a comfortable place to be."
Sjoquist said BPA will send a letter to residents at the end of the month explaining how well the cleaning worked and what the regional energy wholesaler plans to do about the problem. The agency also will hold a public meeting in January.
BPA doubled the voltage flowing through the line as part of a general upgrade of its power transmission network in the Pacific Northwest. The line was built to carry 500 kilovolts, but had carried about half of that since the 1970s.
All 500-kilovolt lines make noise, but not as much as the Maltby lines, Sjoquist said.
The noise is so bad that residents have talked about suing BPA over not being able to sell their property and over how the piece and quiet of Maltby has been destroyed.
Crist said the noise levels vary from day to day, apparently linked to how much moisture is in the air. The noise has become such a focus for her that she has identified four levels.
"We get the buzz," she said of the first, quietest category. "That’s tolerable."
"We get the rattle. We can live with that.
"Then there’s something I call the clatter, and it’s continuous," she said.
Lastly, there’s "whiz clatter, and it’s bad," she said. "It’s like a shrill whistle. It gets to this high-pitch twang. It’s auditory torture."
Reporter Lukas Velush: 425-339-3449 or lvelush@heraldnet.com.
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