Section 2.1 (Site Layout Review) and Table 1 (Summary of Effects and Significance Prediction Comparison of Site Layouts) – The revised layout adopted by the proponent appears to yield sound levels that should normally be below Health Canada’s acceptable threshold value of 45 dBA for sleep disturbance at the exterior of the building of the nearest sensitive receptor (WHO, 1999). However, if a 5 dBA to 8 dBA increase in sound due to the proximity of the ocean were assumed and an additional +/− 3dBA were included to account for model uncertainties, noise levels may exceed 45 dBA. Thus, predicted sound levels, even under assumed worst-case conditions, may underestimate measured levels by 5 dBA or greater. For example, at another wind farm in Nova Scotia, maximum sound levels were estimated to be 49 dBA using ISO9613-2, however, measured values were as high as 54 dBA when wind speeds were 5 m/s blowing on-shore from the ocean (Howe, Gastmeier, Chapnik Limited, 2006).
- Health Canada advises that noise monitoring be undertaken under varying climatic conditions in order to ensure that noise levels do not exceed the acceptable level, and if exceedences are identified, that appropriate mitigation be implemented to reduce the noise level to an acceptable level.
Section 3.2.2 (Effect of Water on Noise Levels) – The report states that “it has generally been considered that the increased background wind noise will cause some masking of the sound levels from the turbines” and “if there is an enhanced stability, the wind that causes background sound may not increase as much as that which causes sounds from the turbines”. These statements can be misleading as turbine noise is likely to be audible to the nearest receptors in the form of continuous low-level or intermittent swooshing, as well as low frequencies at approximately 50 Hertz. As such, Health Canada advises the following:
- Please omit statements about noise masking as they can be misleading; and
- Please ensure that nearby residents are informed that turbine noises may be audible in terms of a low-level continuous or intermittent swooshing, as well as at low frequencies around 50 Hertz.
Section 3.2.3 (Noise Mitigation) – The report states that “noise monitoring [will be conducted] on a routine basis or complaint basis”. In addition to the plan for monitoring and complaint resolution, which is intended to help mitigate any adverse community reaction, it is advisable to also implement a communication strategy. Accurate information with respect to potential acoustical effects related to the operation of the turbines is an essential part of any effective communication strategy.
- Please ensure that any communication effort presents factual information with respect to expected noise levels, including information pertaining to the audibility of operational noises (low-level continuous, intermittent swooshing or low frequency noise), and also includes the potential effects of specific noise levels on human health (see the following comment below).
Appendix B (Addressing Concerns with Wind Turbines and Human Health) – The final sentence in Appendix B states that “there is no peer-reviewed scientific evidence indicating that wind turbines have an adverse impact on human health”. In fact, there are peer-reviewed scientific articles indicating that wind turbines may have an adverse impact on human health. For example, Keith et. al. (2008), identified annoyance as an adverse impact on human health that can be related to high levels of wind turbine noise. In addition, there are several articles by Pedersen (and others) related to wind turbine annoyance (as referenced below). The relationship between noise annoyance and adverse effects on human health is also further investigated in the manuscript by Michaud et. al (2008).
- Health Canada advises that this statement be revised to indicate that there are peer-reviewed scientific articles indicating that wind turbines may have an adverse impact on human health.
Howe Gastmeier Chapnik Limited (HCG Engineering). 2006. Environmental Noise Assessment Pubnico Point Wind Farm, Nova Scotia. Natural Resources Canada Contract NRCAN-06-00046.
Keith, S. E., D. S. Michaud, and S. H. P. Bly. 2008. A proposal for evaluating the potential health effects of wind turbine noise for projects under the Canadian Environmental Assessment Act. Journal of Low Frequency Noise, Vibration and Active Control, 27 (4): 253-265.
Michaud, D., S. H. P. Bly, and S. E. Keith. 2008. Using a change in percentage highly annoyed with noise as a potential health effect measure for projects under the Canadian Environmental Assessment Act. Canadian Acoustics, 36(2): 13-28.
Pedersen, E., and Halmstad, H. I. 2003. Noise annoyance from wind turbines – a review. Swedish Environmental Protection Agency, Report 5308. Pedersen, E. and Persson Waye, K. 2008. Wind turbines – low level noise sources interfering with restoration? Environmental Research Letters, 3: 1-5.
Pedersen, E., and Persson Waye, K. 2007. Wind turbine noise, annoyance and selfreported health and wellbeing in different living environments. Occup. Environ. Med. 64: 480-486.
Pedersen E. and Persson Waye, K. 2004. Perception and annoyance due to wind turbine noise – a dose-response relationship. J. Accoust. Soc. Am. 116: 3460-3470.
World Health Organization (WHO). 1999. Guidelines for Community Noise. Eds. B. Berglund, T. Lindvall, D. H. Schwela. WHO: Geneva.
Van den Berg, F., Pedersen E., Bouma, J., and R. Bakker. 2008. Project WINDFARMperception. Visual and acoustic impact of wind turbine farms on residents. FP6-2005-Science-and-Society-20 Project no. 044628: 1-99.
Download original document: “Health Canada’s response to the Digby Wind Power Project Addendum, Digby, Nova Scotia”
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