Acoustic testing of the Hoosac Wind turbines in Monroe and Florida show that noise levels have exceeded the maximum decibel range permissible for the 19-turbine New England Wind facility.
Wind turbines in Massachusetts are not allowed to exceed the ambient noise-level of their surroundings by more than 10 decibels. But in four measurement samples taken in January and February, acoustic engineers found higher-than-acceptable noise levels in both Monroe and Florida. The “loudest” of these tests occurred on Feb. 20, when the average turbine noise in Monroe and Florida was about 17 decibels above the general noise of surroundings, when no turbines were running. The unusual sound-level was attributed to ice on the turbine blades.
The parent company, Iberdrola Renewables, has promised to take corrective measures by year’s end. In a letter sent to the Western Massachusetts Department of Environmental Protection office on April 28, the company says it will:
∎ Install trailing edge serrations (saw-like edges) on the blades to reduce the overall turbine sound.
∎ Develop an operational protocol to address potential turbine noise for when the blades are coated with ice.
∎ Hire an independent engineering service to “study the tonality in more detail.” According to Western Mass. DEP spokeswoman Catherine Skiba, a tonality study is a detailed analysis of where on the turbine the sounds are coming from.
The letter goes on to say that “New England Wind will review these results with DEP once the study is completed.
The testing first took place in 2013, after DEP had received numerous noise complaints from residents in Clarksburg and Florida, said Skiba. She said the DEP requested additional sites to be tested, on Tilda Hill in Monroe and on Moores Road, which were performed this year, on Jan. 9 and Feb. 20.
Since the letter was written, Iberdrola Renewables has invited 60 neighbors to an information session, to hear landowners’ concerns, give them copies of the sound test results and discuss the planned modifications.
Skiba said the DEP has received 58 complaints since the 28.5-megawatt wind farm started up, in December 2012.
Nine of the 340-foot-tall wind turbines are located in Monroe and 10 are situated in Florida.
The sound analysis was done by RSG Inc, an independent Vermont-based company that specializes in acoustic analysis.
According to GE, the manufacturer of these turbines, the average wind-turbine sound is about 43 decibels, which is slightly louder than a refrigerator (40 dBs) but softer than an air-conditioner (50 dBs).
The ambient noise-level in Florida and Monroe without running turbines, about 27 dBs, is almost at the bottom of the noise scale; so a 10-decibel increase is a noticeable increase in loudness.
Opponents of the windmills have repeatedly cited noise pollution as a concern.
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