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Noise

When the volunteer members of the Wind Subcommittee were researching the topic in order to write an ordinance to regulate industrial wind turbines in our town, they concurrently prepared a document of their findings, aptly named Findings and Rationale. What follows is the summation of what they discovered about the sound and vibrations generated by industrial wind turbines and their effect on the surrounding population.   They discovered that the sound issue is not well understood, and that current sound measurements and models were not adequate for this technology.  They also discovered that the ambient sounds are different for different locations, for example, in an urban setting versus a rural setting, and that sound guidelines have not acknowledged this difference. 

Note the abbreviation WTG = Wind Turbine Generators

Part II – Sound Limitations

  • Improper and inadequate sound measurements have consistently favored the needs of the industry over the needs of the residential, quiet rural communities where they are sited. This has resulted in turbines placed too close to where people live, with real, negative impacts on people, their health, well-being, peace of mind, financial status. In far too many cases, these adverse effects have been severe, and borne not by the greater community, but by those individual families who, through no fault of their own, find themselves in an unliveable situation caused by improperly sited WTGs. The scientific, medical literature and the news outlets, including the Internet, document these at great length and detail, in print and in video, in the USA and abroad.

  • Unlike other urban or suburban sounds, or loud industrial noise, or traffic noise, those living near these WTGs report being unable to get used to the noise. Rather, reports describe that affected populations become increasingly sensitized to it. Employees in loud factories, or people exposed to traffic noises, or other noises can usually get away from them at home. Because WTGs generated noise occurs at home, 24 hours a day, 7 days a week, individuals cannot escape it. The only cure, is proper sound measurements, resulting in protective setback distances.

  • The noise generated by the WTGs is turbulent broadband noise often described as a jet engine perpetually revving for take-off as the blades move through the air, and a sonically unique and repetitive “wooshing” “thumping”, “clapping”, pulsing noise as the blades pass in front of the turbine mast. This noise is more pronounced at nighttime when the air at ground level is still, but the winds high up at the hub of the turbine are forceful enough to turn the turbine at capacity.  Further, the pulsating noise generated by two or more turbines can combine to create louder and more complex noise that carries for longer distances.

  • The most susceptible populations to harmful effects of WTGs noise are young children, individuals with long-term medical conditions, and the elderly.

  • Further, even though many of these WTGs are placed in rural/wilderness areas, such as the Town of Montville, which are very quiet communities, government agencies charged with the protection of the citizenry, consistently espouse noise limitations more appropriate to urban residential or urban mixed areas whose background noise levels are much higher than urban/wilderness areas such as the Town of Montville. The disruption level of these misguided and permissive noise limitations are the cause of much of the sleeplessness and other real health issues suffered by residents near these WTGs.

  • The World Health Organization (WHO) in its reports “Guidelines for Community Noise” and “Report of the Third Meeting on Night Noise Guidelines” recommends that evening and nighttime sound levels should be less than 30 dBA to protect children’s health. Below are some references made in its “Community Noise” (Berglund et al, 2000):

    • “It should be noted that low frequency noise...can disturb rest and sleep even at low sound levels
    • For noise with a large proportion of low frequency sounds a still lower guideline (than 30 dBA) is recommended
    • When prominent low-frequency components are present, noise measures based on A weighing are inappropriate.
    • Since A-weighing underestimates the sound pressure level of noise with low frequency components, a better assessment of health effects would be to use C-weighing.
    • It should be noted that a large proportion of low frequency components in a noise may increase considerably the adverse effects on health”
    • The WHO also states: “The evidence on low frequency noise is sufficiently strong to warrant immediate concern”
    •  For sounds that contain a strong low frequency component, which are typical of the sound emitted by wind turbines, the WHO says that limits may need to be even lower than 30 dBA to avoid harmful health impacts. The WHO further recommends that the criteria be based on dBC frequency weighing.

  • The low-frequency vibrations, known as dBC, is not usually measured by wind developers, and yet, this is the component that more than the other is the cause of severe health impacts. A reading of the dBC noise level, in addition to the dBA readings, is far more predictive of loudness.

  • Although the siting of WTGs in the United States consistently favors the needs of the wind developers over the needs for quietude of families living near the WTGs, history shows that they are capable of meeting far stricter sound limitations which have evolved over the 20 plus years of experience in other continents with these industrial facilities. Below is a listing of the sound limitations in place overseas, as compared to those used in the United States:

• Australia: higher of 35 dBA or L90 + 5 dBA
• Denmark: 40 dBA
• France: L90 + 3 dBA (night) and L90 + 5 dBA (day)
• Germany: 40 dBA
• Holland: 40 dBA
• United Kingdom: 40 dBA (day) and 43 dBA or L90+5 dBA (night)

In the USA:
  • Illinois: Octave frequency band limits of about 50 dBA (day) and about 46 dBA (night)
  • Wisconsin: 50 dBA
  • Michigan: 55 dBA

  • Further, the International Standards Organization (ISO), an independent organization in ISO 1996-1971 recommends a maximum noise limit of 25 dBA for night time in rural communities. (See table below).

ISO 1996-1971
Recommendations for Community Noise Limits (dBA)


 
 
 
Daytime  Limit
 Evening Limit
7 pm - 11 pm
 Night Limit
11 pm - 7 am
   
Rural
   
 
35 dB
 
30 dB
 
25 dB
  Suburban  40 dB 35 dB 30 dB
  Urban residential  45 dB 40 dB 35 dB
  Urban mixed  50 dB 45 dB 40 dB

 

  • From the State of Maine’s Technical Assistance Bulletin #4 – Noise. May 2000:

Prolonged noise exposure is a serious threat to human health; it can result in high stress levels and, at high sound levels, impaired hearing. Common environmental noise sources can cause or contribute to stress-related illnesses such as cardiac and circulatory diseases. Noise can also negatively impact concentration, communication, and sleep creating annoying and sometimes even hazardous conditions. These factors are important in setting noise standards for the community. [.....] It is also important to protect neighborhoods so that residents can communicate and enjoy their property. Residential areas should also be protected from noise so that residents are able to obtain uninterrupted sleep. Interrupted sleep can result in serious health impacts and also affect personal safety at home and at work. Another consideration for municipal officials is property values. Neighborhoods subject to noise disturbance will generally have lower values.

Nighttime noise is more annoying than daytime noise and may cause more noticeable health impacts through the disruption of sleep. — Pages 2 and 3

  • Finally, the same document (Page 2) identifies the Sound Pressure Level (dBA) for a “quiet house interior or rural nighttime” as 20 dBA even lower than the ISO’s 25 dBA.

Conclusion:

The Town of Montville is a rural environment, and as such, sound limitations should reflect the quiet nature of its surroundings. Many of its residents have come to Montville from noisier urban environments attracted by its rural character, peaceful, quiet surroundings and community values. Given the abundant documentation readily available from independent professionals and researchers, it is unconscionable that any governing entity, at the local, state or higher level, charged with protecting the health, safety and well being of its citizens, would inflict avoidable hardship on them through either ignorance, carelessness, indolence or undue influences by powerful interested parties with conflicts of interest and their lobbyists.


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