MONTPELIER – The public and professionals argued appropriate sound limits for industrial wind turbines at a Public Service Board (PSB) workshop on Dec. 2 at the Capitol Plaza Hotel.
The split was visible from the start. Those who have opposed state officials’ approach to wind legislation sat on the left, wearing jeans and flannel or sweaters beneath yellow vests. Many had driven from Franklin County, like Swanton resident Christine Lang, Fairfield’s Sally Collopy and Penny Dubie and Franklin-4 House Representative Marianna Gamache. Meanwhile, state agency representatives and international sound professionals sat to the right in business suits.
Act 174 necessitated the workshop. The last legislative session produced the law, previously known as S.230 or S.260. The law promises “substantial deference” to municipalities with regional plans meeting a new set of regional energy planning standards, including sound limits for wind turbines.
Professionals argue that 45 decibels (dB) at the exterior of one’s house is a reasonable limit. That’s about the volume in a public library. Opponents among the public argue even that volume will produce adverse health effects.
Pre-approved parties were to present 10 minutes and then answer 20 minutes of questions at Friday’s workshop. But those parties were also able to cede time to each other. Representatives from Green Mountain Power, Resource Systems Group and the Vermont Agency of Natural Resources immediately ceded time to two Canadian scientists speaking on behalf of the Department of Public Service, Dr. Chris Ollson and Payam Ashtiani.
Ollson cited dozens of peer-reviewed studies concerning the health effects of multiple wind turbine sound volumes, in particular an unusually comprehensive two-year study by Health Canada completed in 2014. Researchers in that study examined subjects’ blood pressure, took hair cortisol samples to scientifically examine stress levels and performed sleep tests. Their conclusion: any turbine sound level below 40 dB is safe for public health.
Ollson recommended a 45 dB external limit, meaning the limit of audible sound at the edge of someone’s home. Opponents call for an internal sound limit as well, but Ollson said the complexities of monitoring and calculating an internal sound limit render the enforcement of such a rule “impossible.”
“We recognize there’s an annoyance factor,” Ollson told the board, but public complaints do not have a scientific health basis. With that in mind, he suggested state agencies resolve those complaints on a case-by-case basis, through tactics like buyouts and easements.
Fairfield resident Greg Pearce, a retired professional engineer, asked Ollson if he supported establishing a “setback distance” for wind projects, a set distance separating the project site from nearby properties. Ollson said he did not, that setback distances do not necessarily correlate to turbine sound levels. He reiterated that approximately 46 dB of sound is a safe limit.
A representative from Vermonters for a Clean Environment, who videorecorded the entire five-hour workshop, asked Ollson to disclose if he had worked for any industrial wind developer as a hired expert, and if he continued to do so in the future. Ollson said yes, that environmental siting is his specialty, leading him to steady work with both private developers and state agencies, and that he expected to continue working with both.
A Starksboro resident challenged Ollson to explain “vibroacoustic disease,” a reported illness ostensibly caused by longterm exposure to low frequency noise. Ollson said the initial studies announcing the illness were “really not credible,” and specifically cited subsequent studies discrediting the initial reports.
Another member of the public asked Ollson why the State of Vermont does not conduct its own relevant health studies. Ollson clarified that he was not best-qualified to answer that, not being a state official. But he pointed out that such studies are not commonly done by states, and that the “breadth” of studies on the health effects of turbine sound rendered additional studies unnecessary.
“If you need to do a heart surgery, you’re not going to say, ‘Well, let’s do our own study of this, in Vermont,’” Ollson said, to audible scoffs from the public, “because there’s already a wealth of information on heart surgeries out there.”
Ashtiani’s presentation proposed modeling parameters for turbine sound monitoring, including the ground factor, temperature and humidity and the sound power input used. He recommended measurements at one-minute intervals. His presentation was concise but complex. At its end, he concurred with Ollson: 45 dB is a safe limit.
St. Albans attorney Paula Kane asked Ashtiani if he had been tasked with identifying an appropriate sound level or clarifying if 45 dB was safe. Ashtiani initially said those were the same tasks, but did reticently agree that he had focused on proving 45 dB safe. Ollson attempted to alleviate concerns by noting that research suggests even 50 dB is a safe sound level, provoking heated whispers and more scoffs from the public audience.
Dubie asked Ashtiani if he recommended an average sound limit of 45 dB or a maximum sound limit of 45 dB. She noted that an average, calculated based on sound levels over a period of time such as an hour, can include many “peaks and valleys,” sound highs and lows. Ashtiani said those sound levels should be measured over a shorter time than an hour for greater precision, but said he supports an average sound limit.
State officials and corporate representatives asked as many questions as members of the public, though without the need to cross ideological lines, theirs required shorter answers.
Collopy has repeatedly questioned the effect of turbine sound from the proposed Swanton Wind project carrying over the water of Fairfield Pond. She asked if his studies included the effects of sound over water, and he said yes. It’s considered a reflective surface, he said. “Sound propogates more efficiently over water,” Ashtiani said. “Though the actual sound level won’t increase.”
Ashtiani also said he did not support a setback distance, for a different reason: that establishing a setback distance reduces the incentive for wind turbine manufacturers to develop increasingly quiet turbines.
Both Ollson and Ashtiani spoke in support of regular post-construction sound monitoring. “No one ever bought a dishwasher that got quieter over time,” Ashtiani said, to laughter from both sides.
However, a representative from the Department of Public Service said the agency currently plans only initial monitoring, followed by further monitoring after five years.
Collopy planned to speak at the event, but ceded her time to Stephen Ambrose, an “acoustic investigator” and former professional engineer who spoke on behalf of Vermonters for a Clean Environment. Ambrose’s presentation, a comical slideshow with images of a baby interspersed between charts and quotations, provoked his fellow professionals as much as their presentations irked the public in attendance.
Ollson and Ambrose shook hands prior to the presentation and privately caught up. When Ollson stood during Ambrose’s presentation, he made the prefatory statement that the two frequently encountered each other and respected each other, though they had “wildly different views.” And with that, Ollson poked holes in the re-organization of study data in Ambrose’s presentation and disputed the design of Ambrose’s cited studies, leading to the central statement of the workshop.
“We have devalued human hearing,” an irate Ambrose said.
Members of the PSB tried to clarify in closing remarks that the day was designed to be an “educational” workshop – that a chance for testimonials and a public hearing would follow once rules were even proposed. The PSB has not, as of yet, proposed a concrete sound rule.
Someone in the audience protested that “one side of the room got all the time.” PSB Chair James Volz fired back, “Because the people in the yellow vests asked so many questions.”
Future dates for the rulemaking process have not yet been issued.