“Understanding Sound Associated with Industrial Wind Developments”, was the theme of the presentation by Rick Bolton, Engineer & Sound Specialist, and sponsored by Citizens for a Healthy Rural Neighborhood (CHRN), on Wednesday, January 30, at Perry’s Masonic Temple.
Though Wednesday’s inclement weather prohibited attendance by many from outlying areas, citizens and Town Board members from Perry, Gainesville, Leicester, and Orangeville were there. Mr. Bolton’s presentation was designed to convey a basic understanding of the complexities of sound, effects on humans, and flaws in current analysis standards being employed by wind developers in the U.S.
Mr. Bolton began by explaining that sound associated with wind turbines is an extremely complex issue, and one that needs thorough analysis. “Sounds are waves – just like light and water,” he said. These sound waves are measured in deci-Bels (dB, or dBA – A-weighted deci-Bels – most closely imitate the human ear).
“Human audibility is extremely sensitive,” he said. “In fact, far more sensitive than anything we can use to record sound electronically. While the human ear can detect to 0 dBA, the lowest range even the most expensive noise meters can measure is 14 dBA.”
Elaborating on the factors that can amplify sound, Bolton pointed out:
1.) Sound can propagate for over a mile, and even further over water;
2.) Sound gets worse in water (i.e. – ice, fog);
3.) Low frequencies can double sound by refraction off hard surfaces (hillsides, snow-pack);
4.) ‘Wave Coherence’, created by a number of turbines together, amplifies sound;
5.) When the wind is blowing, it can refract noise from the elevated source-point downward;
6.) Sounds below 30 Hz, termed ‘infrasound’, create serious health problems (turbines have been indicated as being a strong source of ‘infrasound’)
7.) Ice-loading on the front edge of turbine blade tips disturbs air flow around the blade, creating turbulence, and increasing sound.
8.) Modulation occurs when the blade compresses air as passing the mast of the turbine, and is worsened by large groups of turbines’ blades not operating in sync. (Bolton has never seen modulation addressed in any wind developer provided studies.)
Bolton explained the many ways wind developers methodology is flawed. Field measurements are not done correctly (i.e. – improper microphone placement, no justification for sampling sites, etc.); accurate samplings need to be done for a full year to account for seasonal variations, but aren’t; and computer prediction models wind developers rely on are inadequate because they don’t account for modulation, coherence, refraction, and icing.
Facts contained in Perry’s DEIS from the sound study done by Horizon for Perry were brought up that highlighted Bolton’s point that sound studies being done are totally inadequate: “5 monitoring locations; Survey was carried out over roughly a 3-week period; Unfortunately, 3 primary & 2 backup instruments were destroyed by water infiltration, so octave band data could not be collected for ALL positions for the entire 3-week survey; There were a number of periods of either inclement weather or low wind speeds – conditions that are not generally useful; General conditions of temperature, barometric pressure, & wind for the survey period are shown in plots below as observed at DANSVILLE, NY – some 20 miles southeast of the site.”
Illustrating and explaining his points with numerous charts and graphs that were part of his presentation, he also included examples and measurements from homes that had been abandoned by their owners due to the resulting life-altering health effects of living too close to turbines. Not surprisingly, these health problems have been linked to sleep disturbances.
The World Health Organization (WHO) guidelines recommend that sound level should not exceed 30 dBA for a good night’s sleep. WHO also unanimously agrees that noise levels greater than 42 dBA create sleep disturbances, and that disturbed sleep has serious health effects.
Bolton explained that rural country settings currently enjoy extremely quiet night-time noise levels of 20 – 30 dBA. However, wind developers typically propose 50 dBA as acceptable noise levels at property lines of neighboring homes to their industrial wind installations. They do so despite the fact that the NYS DEC recommends no more than a 6 dBA increase over existing night-time ambient noise levels.
“Every 6 dBA is a perceived doubling of sound, or loudness,” Bolton said. When you understand this, you can begin to understand the problems that are occurring from siting these facilities far too close to people’s homes in rural areas. Bolton’s research suggests that 3,000′ – 5,000′ setbacks from the nearest property line should be the rule of thumb.
Neither citizens, nor the town officials being rushed through zoning, siting, and approval processes by wind developers truly understand the vast difference between 30 and 50 dBA until it is too late. Bolton stressed the importance of “getting it right” before allowing industrial wind facilities to be built, since mitigation after the fact is not available. He has yet to see wind developers do any follow-up studies for those now experiencing problems. They simply ignore them.
Bolton also explained that NY Townships are perpetuating flawed methods by accepting, and placing in their ordinances, the 50 dBA sound levels being submitted by wind developers, without demanding justifications – despite the fact that this is contrary to SEQR rules. NYS DEC’s Environmental Conservation Rules for SEQR state that the noise pollution potential must be evaluated at each affected “receptor”.
NYS DEC’s Program Policy, “Assessing & Mitigating Noise Impacts”, states: “When a sound level evaluation indicates that receptors may experience sound levels or characteristics that produce significant noise impacts, or impairment of property use, the Department is to require the permittee or applicant to employ necessary measures to either eliminate, or mitigate, adverse noise effects.”
If our townships fail to hold developers accountable to required standards, “we will lose the privilege, and precious asset, of having the peace and quiet of the country,” he said.
Mr. Bolton then took questions from the crowd. In response to questions asking what he thought of being “surrounded” by up to 23 turbines within 1.5 miles of their homes, he answered, “I would be VERY concerned if I were you.”
When asked if he has conducted any studies in the Perry area, Bolton replied that he had. Those who attended Perry’s Public Hearing October 16, 2006, will remember Mr. Bolton adding his comments, and handing in the study he did for Perry to the Board that evening. (Mr. Bolton’s comments on the Noise Issue can be found in the Comments to Perry’s DEIS under H-1, pages 1-24.)
By Mary Kay Barton
Batavia Daily News
6 February 2008