The Maine Department of Environmental Protection (DEP) found that the wind turbines on Vinalhaven exceeded the nightly legal noise limit of 45 decibels in July and was likely to have exceeded the limit in May, according to Becky Blais of the Maine DEP.
A report filed by Warren Brown of Enrad, a consultant hired by the Maine DEP to conduct sound studies, states that the nighttime sound levels were as high as 48 decibels for seven- to ten-minute intervals at an abutting property and that the intervals of higher sound were repeated. Decibels are exponential measurements, so each additional decibel significantly increases the volume.
In his report to the Maine DEP, Brown stated there was sufficient evidence that the sound limits had also been exceeded on several nights in May.
Brown recommended that substantial changes be made for night-time operations of the three wind turbines so as to not exceed 45 decibels.
Brown further noted that the wind speed measurements taken by the consultant for Fox Island Wind in 2008 did not supply adequate data to determine an accurate wind speed correlated to sound levels. This data was taken from an intrument placed higher in elevation than the Maine DEP requires and was recorded in an area obstructed by a building and a tree, according to Brown’s report to the Maine DEP.
George Baker of Fox Island Wind (FIW) said that there will be a meeting with the Maine DEP later this week to talk about the difference in the studies done by the two consultants and to compare their methodologies.
Baker said the FIW consultant corrected the data for ambient noise in the trees, whereas he said it was likely that the data used by the Maine DEP was not corrected for ambient noise. Correcting data for interfering variables, like ambient noise, is a standard analytical approach in working with scientific data, but it is not the only accepted approach.
“We will be comparing methodology,” said Baker. “It’s very important how you establish sound levels and it’s particularly problematic in woodland sites.”
Trees, in other words, make their own noise.
Baker said the DEP had not asked FIW to take any action.
“We will absolutely comply with state laws,” said Baker. “If it comes to needing to turn the turbines down, we will do that. I hope that doesn’t happen. It will cost electric rate payers a lot of money if we do.”
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