Experts: change town noise standard
LAFARGEVILLE — Two local noise experts advised the Orleans wind committee to change the basic noise standard used in the town law that governs wind power development.
Clifford P. Schneider, retired fisheries biologist with the state Department of Environmental Conservation, was invited to present a paper he wrote on stable atmospheric conditions and noise at two international conferences.
He told committee members the town's current law uses an odd measurement for its noise standard. The ordinance allows for up to 50 decibels 10 percent of the time, which measures what experts call "impulsive" noise.
Instead, Mr. Schneider said, sound standards are usually based on noise that's present 90 percent of the time.
He cited a study by George F. Hessler, who has conducted many sound studies for wind developers in the state, which recommended perception-based methods of noise standards as opposed to a single emissions level.
The current law with a flat 50-decibel standard is an example of a single emissions level. Cape Vincent's standard of no more than 6 decibels above ambient is an example of perception-based standards.
Other experts in the field agree perception-based noise standards are best. Those experts include Cavanaugh Tocci Associates, the Sudbury, Mass., acoustic engineering firm that drafted noise standards for Cape Vincent, and George W. Kamperman and Richard R. James, two sound control engineers who authored a wind turbine siting guide.
In this area, Mr. Schneider said, the worst-case scenario for noise creation would happen regularly, called atmospheric stability. That is, in the evening and at night as the ground cools, there is little wind near the ground surface, but lots of wind a few hundred feet up.
"This is when wind turbines will operate at their loudest," he said.
Based on measurements he's taken, stable atmospheric conditions occur during 67 percent of the nights from June to October.
In its draft environmental impact statement, Horse Creek developer PPM Energy, a subsidiary of Iberdrola, estimated the turbines would create 45 to 50 decibels of noise. The measurement for night-time noise was 26 decibels.
"This means the noise could frequently exceed 20 decibels above ambient, which according to DEC guidelines is very objectionable or intolerable," Mr. Schneider said. "And this frequently-occurring condition is permitted under the current town of Orleans law."
Following Mr. Schneider, Paul E. Carr, engineering professor at Cornell University, Ithaca, and one of the founders of Bernier, Carr & Associates, Watertown, talked about a variety of setback concerns. He mentioned an operations handbook from Vestas, the Danish wind turbine manufacturer, which told staff to stay at least 1,300 feet away from operating turbines.
"From my public safety standpoint, 1,300 feet would be the starting point for setbacks,""Mr. Carr said.
He showed maps of the array layout of the St. Lawrence and Cape Vincent wind farms and the layout of the Horse Creek Wind Farm.
In an array layout the turbines are distributed evenly to limit interfering and to allow the turbines to produce energy from wind from any direction. Mr. Carr said 1,250 feet between turbines eliminates the interference.
Many New York towns have adopted ordinances that call for setbacks of 1,250 feet from residences and ceilings of 50 decibels of noise. Mr. Carr said these towns and the New York State Energy Research and Development Agency, which uses many examples of those setbacks in making suggestions in towns, have created a policy that benefits the developers.
"It allows them to get build the maximum number of turbines they can cram in one area," he said.
The Horse Creek Wind Farm, with its lines of turbines, was designed to take advantage of prevailing west-to-southwest winds.
"It does have strategic open areas for roads," Mr. Carr said.
But, he said, the data PPM Energy submitted shows the wind farm will have noise far exceeding DEC recommendations.
"To get noise to decrease just enough takes quite a bit of distance," he said.
By a PPM map, it would take about 3,300 feet from a turbine to have noise levels go to about 35 decibels.
Both Mr. Schneider and Mr. Carr recommended the town have an ambient noise study done by an independent firm. They also suggested studies should include low-frequency noise and compliance isssues.
"It is so important to do an ambient noise survey because there are so many unique characteristics in different communities," Mr. Carr said.
