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For Sheffield Wind, how you measure could be as important as what you measure

The Public Service Board is about to set rules for monitoring sound levels emitted from turbines at Sheffield Wind Farm, standards that could set a precedent for other projects to come.

“Our docket is sort of a laboratory to critically examine through a contested hearing what sort of protocols need to be applied, that’s why the hearing is so important,” said Paul Brouha, who lives near the project.

Brouha filed a noise complaint with the PSB in 2011 and has been battling to prove his case ever since. In 2012 Vermont Wind, which owns the facility, persuaded the board that the company was compliant with the sound standards set in its certificate of public good (CPG).

In the years that followed, Brouha hired Les Blomberg of Noise Pollution Clearing House in Montpelier to challenge that assessment. By 2015, they had convinced the PSB to require new noise monitoring be done at Brouha’s property.

But instead of using the methodology already in place from the existing noise monitoring plan, the board has asked both parties for input on new protocols for measuring the noise.

“That is the struggle we are in right now,” said Blomberg. “We are trying to figure out how to measure the noise and how you measure can have huge implications as to whether or not you find a violation.”

All about the decibels

One point of contention is how the existing background noise should be measured.

Blomberg explained that he has to take measurements with the turbines off to get all the background noise recorded, then subtract that from the total noise level with the turbines turned on.

Vermont Wind proposes leaving some of the turbines on during the background measurements, essentially closing the gap between the on and off measurements.

Blomberg said that makes proving a violation more difficult.

“This methodology effectively changes the CPG, which is what was issued by the board,” said Blomberg.

Brouha said that measuring background noise with some turbines left on effectively raises the sound limits from the CPG by several decibels.

Annette Smith, director of Vermonters for a Clean Environment, said the extra round of sound monitoring is obscuring the fact that Vermont Wind has already been caught in violation of interior sound limits.

The CPG rules bar more than 30 dBA of sound inside a home at night. When the board first cleared Vermont Wind of any violation in 2012, Blomberg said the PSB did so with the assumption that sound traveling from outside to inside the house attenuated about 15 dBA. But measurements by Blomberg and other experts found that the reduction is only a few decibels. They also determined that the project was in violation of its certificate of public good about 10-to-15 percent of the time.

At that point, Smith said, Vermont Wind should have been cited for a violation.

Instead, she said, “Paul is having to spend tens of thousands of dollars to work on a new protocol for monitoring when there was a monitoring protocol that was agreed upon.”

The Public Service Board will not comment on ongoing cases.

Blomberg said he expects a decision on the protocols within a couple of weeks. The actual monitoring would likely start a few weeks after that.