Sound the main issue at Public Service Board hearings on Lowell wind farm

Kenneth Kaliski of Resource Systems Group argued that the board's standard is more conservative than noise guidelines from the World Health Organization, the US EPA, and other organizations. Photo by Carl Etnier.

The Public Service Board began its third week of hearings on the Kingdom Community Wind project in Lowell with a bang. Or at least with the argument by a noise expert that wind turbines sound similar enough to banging noises like explosions, guns firing, and sonic booms that the Public Service Board ought to require the developers to ensure that their sound is quieter than it otherwise would need to be.

Leslie Blomberg, executive director of the Noise Pollution Clearinghouse in Montpelier, testified on behalf of the Lowell Mountains Group, which opposes the 63 MW, 20- or 21-turbine project that Green Mountain Power has proposed in Lowell. He argued that the Public Service Board has applied a too-lax standard to other utility-scale wind projects permitted in Vermont, and he wants a tougher standard for the Lowell project.

The Public Service Board has required that other wind projects keep the sound under 45 decibels, as measured at the exterior of a dwelling and averaged over an hour. Sound experts have testified that this would give a 30 decibel sound level inside the house. Green Mountain Power has proposed a sound monitoring and response plan for the Lowell project that they say would ensure that this standard is met.

The Lowell Mountains Group is arguing for a lower standard, applied outdoors at the property line, arguing that neighbors to the wind farm may wish to set up a chair and enjoy the outdoors closer to the property line than their house. Or they may wish to build another house or a cottage closer to the wind turbines, where the sounds may be louder, and they would then be prevented from enjoying their new house or cottage.

Dotty Schnure with Green Mountain Power reiterated GMP’s position that they will comply with whatever noise standard the Board applies to the Kingdom Community Wind project. However, the company has not ruled out appealing the Board’s order on the basis of the noise standard used.

Blomberg suggested an outdoor standard of 35 decibels, half as loud as 45 decibels, applied at the property line. He arrived at that number by starting with an EPA document discussing how loud intruding aircraft noise can get before it provokes community reactions. The document notes that sounds of 55 decibels do not provoke a reaction in urban areas, but that the threshold in rural areas is 10 decibels quieter. The threshold is reduced a further 5 decibels when there’s been no previous experience in the community with intruding noise, and another 5 decibels when the noise has “impulsive characteristics,” which Blomberg asserted wind turbine noise has.

Green Mountain Power attorney Peter Zamore asked Blomberg to read the EPA’s definition of impulsive noise and its examples, which include explosions, firearm discharges, sonic booms from aircraft, and industrial processes. Zamore questioned whether wind turbines actually sound like that. (Various parties in previous Board hearings on this project have characterized the noise as “swish-swish.”) Blomberg argued that the examples are not all-encompassing, and that wind turbine noise meets the EPA definition.

Board member John Burke acknowledged that Board “struggles” with questions of noise standards and how to apply them. But he expressed some skepticism that sounds exceeding 35 decibels at the property line would wake someone up, a consequence Blomberg had called “shocking and offensive.” Burke noted, “An average library has a db [decibel] rating of somewhere between 35 and 40. But you really don’t consider a library to be shocking and offensive, do you?” Blomberg said no. Burke also noted, to laughter in the hearing room, that he had had no difficulty sleeping in libraries in college.

Under questioning by Lowell Mountains Group attorney Brice Simon, Kaliski admitted that the wind turbine noise might interfere with other activities, like listening to songbirds, at lower decibels levels.”

Board staff attorney Thomas Knauer questioned Blomberg about another application of the EPA document, putting the threshold for community reaction 5 decibels lower when the community has no prior experience with intruding noise. Knauer pointed out that the loud activities of snowmobiling and logging already happen around the area of the proposed wind farm. Blomberg argued that noise from wind turbines is different. “Logging sounds would tend to not occur at night. That’s what’s really unique about this. Not only at night, but it could happen 24 hours a day, any day of the week. It’s not within your control… I don’t think there’s a source like that in that community right now.”

Before Blomberg took the stand, Kenneth Kaliski, of the Resource Systems Group in White River Junction, testified about sound for Green Mountain Power. Kaliski had conducted a noise impact study for the project, both monitoring background noise and using two different models to predict what levels of noise would be experienced at different places when the turbines were operating.

Kaliski defended the Board’s 45 decibel standard applied immediately outside the home, saying the standard is designed to protect residents from sleep disturbance, and it does so at 45 decibels. He argued that the board’s standard is more conservative than noise guidelines from the World Health Organization, the US EPA, and other organizations. Many other jurisdictions regulate wind farm noise with mandatory setback distances from the turbines, rather than monitored or modeled noise thresholds. Kaliski said that the project would pass muster with setback guidelines from the Congressional Research Service, the National Academy of Sciences, and the Bureau of Land Management, as no year-round residence is closer than 3,200 feet to a turbine.

He acknowledged that areas where people are frequently outdoors might have a standard to make sure they can make themselves heard in a normal conversation. Kaliski said that it takes a 55 decibel sound to interfere with conversation, and that wind turbine noise diminishes to less than that “within a few hundred feet of the turbine.” Consequently, Kaliski discounted a need for a different outdoor standard for these “remote” turbines.

Under questioning by Lowell Mountains Group attorney Brice Simon, Kaliski admitted that the wind turbine noise might interfere with other activities, like listening to songbirds, at lower decibels levels. And he declined to speculate on how the standard affects a property owner who wants to build a new cottage closer to the property line, where noise levels may exceed the 45 decibels outside an existing home on the property.

The noise impact study used two modeling methods, which Kaliski repeatedly characterized as “very conservative.” Yet Jared Margolis, attorney for the towns of Albany and Craftsbury, spent hours questioning him, much of the time about how much the model might underestimate noise as experienced in the real world. The conversation focused on the minutiae of statistical analysis and confidence intervals, as well as study design.

Margolis also pointed out passages in Kaliski’s 2006 testimony before the Board, about wind turbines proposed for Sheffield and Sutton, that seemed to contradict some aspects of his current testimony. In 2006, Kaliski was hired by the Town of Sutton to critique a noise study prepared for the wind developer. However, the issues in the 2006 testimony were quite different; they were about whether the turbines would be audible at all in certain locations. In the current case, the questions are about how loud the sound will be, not whether it will be audible.

While GMP has said it will comply with any noise standard the Public Service Board applies to the project, Margolis questioned whether they would have the tools to do so if real-world noise levels turn out to be higher than expected from the modeling. Turbines can be switched to a “noise-reduced operation” (NRO) mode, but the current project design already calls for NRO mode to be used, perhaps for thousands of hours a year, to comply with the 45 decibel standard. That already expected use of NRO mode erodes the ability to achieve further reductions by using NRO, Margolis argued. That would leave turning the turbines off entirely during certain weather conditions as the only alternative to what Kaliski characterized as the “expensive” alternative of moving the turbines, whose towers alone are around 250 feet high.

Kaliski repeated that the modeling was conservative, and he said that there was no danger that turbines using NRO would exceed a 45 decibel exterior standard.

While the hearing was just to take evidence, Public Service Board Chair James Volz clearly dismissed the need for one part of Kaliski’s future monitoring plan: a five-year limit for noise complaints. Kaliski had proposed that GMP would do new monitoring to respond to noise complaints for the first five years of the project, but after that, they would stop. The exception is when the noise is related to maintenance needs, for example, the turbine blades had become pitted. Board members were skeptical that residents would know why the turbines had become louder; they’d just experience more noise.

Kaliski said that the point was to guard against nuisance complaints — the same person calling in, over and over. “We can deal with that,” Volz assured him.

The hearings continue through Friday.