Green Mountain Power will be required to constantly monitor sound coming from wind turbines, which could provide the most detailed assessment yet of a noise issue concerning some residents living near wind farms.
The Vermont Public Service Board fined the utility $1,000 last week for exceeding sound limits it placed on the Kingdom Community Wind farm, which was approved in 2011.
In place of a larger civil penalty, regulators asked the utility to implement a continuous sound-monitoring program for one year. Regulators said it will cost the utility approximately $109,000 to implement the department’s proposal. The board said GMP cannot recover these costs from ratepayers.
The utility is required under its certificate of public good to keep the noise level at 63-megawatt wind project on Lowell Mountain below 45 decibels on average over one hour outside nearby homes. Regulators determined the company violated the sound limits in winter of late 2012 and early 2013. GMP says the sound violations were caused by snow buildup on the turbine blades.
The company has since installed cameras and weather-monitoring equipment to detect snow accumulation on the blades. Since GMP installed this equipment, no other violations have been reported.
The Department of Public Service this spring drafted a continuous sound-monitoring proposal, which Green Mountain Power supports and has agreed to implement. Regulators determined it would be “more constructive” to require the utility to implement this plan rather than pay a larger monetary penalty.
Vermonters for a Clean Environment, a group opposing the wind project, told the board the methodology of the sound monitoring proposal is flawed and the experts hired to assist its implementation have developed projects that have caused complaints from neighbors about noise.
Public Service Commissioner Chris Recchia said the details of the proposal are still being worked out, but it would be “scientifically based and rigorous.” He said the department does not know when the plan will be implemented.
The department is still evaluating the order and has the option to ask the board to reconsider it, he said.
GMP spokesperson Dotty Schnure said the company has collected 10,934 total hours of sound monitoring data, and has exceeded the regulatory limit for four hours. She said GMP is committed to operating the wind project within its permit requirements.
She said GMP shuts down the wind turbines when weather causes ice or snow accumulation. She said this has always been part of the company’s operating procedure.
The utility again announced on Tuesday it had met noise standards for the latest reporting period from August 20 to Sept. 9. The utility hired the research firm
(RSG) to conduct the report, and critics say the studies are not scientific because they discard data when wind speeds are high near recording microphones and during certain precipitation events.
The department’s proposal requires noise sensitive receptors, or microphones, to be placed around residents homes with direct exposure to the turbine noise. A second microphone would be shielded from the turbines to measure background noise, which is used to control for other noises in the area.
The data will be collected continuously and downloaded for review, according to the proposal. The data would then be summarized for monthly reports. The acoustical consulting firm hired by the department, Acentech Inc., drafted the proposal.
Outgoing board member John Burke said in his dissent he would have preferred a substantial fine be imposed on GMP and would not have ordered the continuous monitoring.
“While the only winner then would have been the State’s general fund, all the parties would begin to realize that working on noise issues is important and that more is gained by working together than by the “my way or the highway” attitude that appears to have prevailed here,” he said.
Burke said no matter what data results from this monitoring, it will likely be criticized and its ultimate value will be diminished, in his opinion.
Annette Smith, executive director of Vermonters for a Clean Environment, does not support the methodology outlined in the department’s sound monitoring proposal. She also said the firms hired by the department have a history in designing wind projects that have caused harmful noise.
Wind proponents say studies show wind turbine noise does not cause harm, but some residents in Vermont say turbines interfere with sleep and cause nausea.
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