It’s unclear whether findings from a $19,000 state study on noise levels for the Vermont Wind Project in Sheffield indicate if the 16 turbines have exceeded state decibel thresholds.
Chris Recchia, commissioner for the Vermont Public Service Department, said that while the noise testing may help his department better understand how to evaluate wind noise in the future, he cannot draw conclusions from it.
“The testing is not helpful in terms of determining wind noise,” he said. “It really is not particularly useful in making conclusions about the compliance of the turbines.”
Recchia said the department contracted the study out to KM Chng Environmental, Inc. in response to Steven and Luann Therrien’s complaints that noise from the turbines was affecting their family’s health. KM Chng took decibel measurements from Dec. 19 to Dec. 21 outside the Therrien residence.
On Dec. 19, when the winds were calm, the average decibel level was 30. On Dec. 21, when the winds were stronger, the average decibel level was 47, and on Dec. 22 the decibel level was 45.
According to the report, a shower is roughly 70 decibels, a refrigerator is 50, a brook is 40 and a whisper is 30.
The permit, or Certificate of Public Good, for the project
stipulates that noise from the project is not to exceed 30 decibels inside surrounding residences. Km Chng did not test inside the Therrien household as required for the permit.
“To do that we would have had to ask the Therriens to refrain from making any noise for three days or to leave the house,” he said. “We felt, and the consultants felt, like if they could distinguish the wind turbine noise from the background noise, they would be able to extrapolate from inside the house without having to disturb them significantly.”
But the consultants couldn’t distinguish between the wind and the sound of the turbines.
“The higher … noise levels on days 2 and 3 were due to the noise generated by the windy weather conditions, and not from the turbine facility,” the consultants wrote. “Any noise from the turbines was inaudible above the wind noise.”
Recchia said that in the future the Public Service Board might need to set different standards that are easily measurable.
“This was our first attempt at trying to do independent noise testing, but it brings up more issues than it probably answers,” he said. “One of them is having a standard inside someone’s house.”