Sonus has relied solely upon the NZ Standard and has ignored the acoustic characteristics that residents will actually receive as a result of the Cherry Tree Farm. They have not addressed the actual acoustic impact of the wind farm on the community.
The Sonus acoustic assessment provides a set of predicted noise levels in terms of the A-weighted values set out in the Standard and concludes that there are no tonal or modulation characteristics requiring modification to the predicted noise levels.
In relation to background levels, the Sonus measurement results confirm (as expected) that ambient background levels outside rural properties are significantly lower than 30 dB(A). As such, the noise generated by the wind farm is likely to be significantly greater than background +5dB(A) and therefore to have an impact significantly greater than for an “annoyance.”
The issue of low frequency noise and infrasound has been raised and discussed above. Documentation from the world’s leading supplier of turbines has identified that computer models are inadequate for low-frequency noise propagation. As high frequencies are rapidly attenuated over distance (when compared to low frequencies) audible characteristics of the turbines may be reduced to a low frequency hum and can also include frequencies below the normal range of human hearing.
The NZ Standard ignores infrasound and low frequency noise.
The SA EPA Guidelines identify that infrasound is not generated on a well maintained wind farm yet the measurement results obtained for the purposes of this report prove otherwise. The measurement data appended to this review identifies that there are both low frequency and infrasound components generated by the turbines that are currently located in the region.
A proper assessment of community impact cannot ignore low frequency noise and “infrasound.” To the extent that it does, when these have been issues of specific complaint with other wind farms, the Sonus report falls short of its responsibility to the community as required by the Code of Ethics of the Australian Acoustical Society and the Code of Conduct of the AAAC.
The SA Guidelines identify that for host stakeholders, sleep disturbance is an adverse health effect. The NZ Standard seeks to avoid adverse noise effects but does not define what constitutes an adverse noise effect.
It is not unreasonable for Council and the community to assume that if sleep disturbance gives rise to an adverse health effect for persons in South Australia who are obtaining a financial gain from hosting turbines, then sleep disturbance that impacts upon the general community (i.e. non-host stakeholders) must also give rise to an adverse health effect. It is not unreasonable to expect people in Victoria to experience similar impacts as those in South Australia.
This peer-review has identified two eminent acousticians who, in 2002/2004, identified that there are issues with low frequency and infrasound and that the ear still continues to work and receive signals even when people are asleep. The mechanism causing sleep disturbance (for example, whether individuals are able to detect the infrasound components) is an issue outside my expertise.
But it is clear that use of the A-weighted value for assessment or compliance purposes does not address all of the noise impact issues associated with wind farms.
The current application has not satisfactorily addressed all of the matters to determine the current acoustic amenity, and has not actually assessed the noise or the impact of the subject development.
Inadequacies of the NZ Standard in meeting the fundamental intent has been raised.
As a result of the various matters raised and outlined above, there can be no confidence that the community will not be adversely impacted by the proposed Cherry Tree Wind Farm. It is recommended that Trawool Valley-Whiteheads Creek Landscape Guardians should request further particulars from the Applicant to address the individual matters raised above with a view to identifying the actual noise impact that will be generated by the proposed wind farm.
Download original document: “Peer Review of Cherry Tree Environmental Noise Assessment”
This article is the work of the author(s) indicated. Any opinions expressed in it are not necessarily those of National Wind Watch.
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