In late 2011 The Acoustic Group performed a desk-top review of the acoustic documents comprising the acoustic assessment for the Flyers Creek Wind Farm and conducted preliminary sound monitoring at an existing operational wind farm (the Capital Wind Farm) which was approved in New South Wales on the basis of similar analyses, guidelines and reports to that provided for the Flyers Creek Wind Farm. The assessment found deficiencies and inadequate information in the acoustic assessment of the Flyers Creek proposal such that the true acoustic impact of the proposed wind farm had not been presented to the community.
In the intervening period a set of Draft Wind Farm Guidelines have been issued by the NSW Department of Planning and Infrastructure (“the Department”) for public comment.
The Acoustic Group was requested by the Flyers Creek Wind Turbine Awareness Group to examine the Draft Wind Farm Guidelines with respect to acoustic issues. As there are no acoustic compliance reports for operational wind farms in NSW in the public domain, The Acoustic Group was also requested to conduct additional testing to assess the Draft Guidelines with respect to practical aspects of their application to operating wind farms.
The Draft Wind Farm Guidelines have identified that they closely follow the existing South Australian Guidelines in relation to the noise criteria. The problem for the broader community in comprehending the Guidelines is that from a noise perspective by definition, the Guidelines must be expressed in technical terms which are not readily understood by the community. The community therefore relies on the preparation by the Department of noise guidelines that set rigorous criteria and assessment procedures as well as a rigorous compliance regime. A reasonable person would expect that such Guidelines would be drawn from and based upon solid data and measurements. Despite the fact that the Department has had the opportunity to scrutinize data and undertake scientific investigations of operating wind farms for the purpose of the Draft Guidelines, it has not done so.
The Draft Wind Farm Guidelines set out measurement, assessment and compliance procedures which are likely to be unworkable in practice. This review highlights a number of outstanding issues in relation to noise impacts from wind farms that require the Draft Guidelines to be amended in order to safeguard the acoustic amenity of residents in areas where wind farms are proposed and where there has previously been no such noise source.
It is recommended that the proposed base criteria for wind farms be amended to 30 dB(A) when assessed under the worst case scenario. In particular, it is concluded:
- There is no material or reference in the Guidelines supporting the use of 40 dB(A) as an acceptable amenity level in rural NSW. Examination of the Department’s compliance review of the Capital Wind Farm confirms Leq levels when turbines are shut down which are significantly lower than 40dB(A) and which undermine this standard as an acceptable amenity.
- The Draft Wind Farm Guidelines ignore “Offensive Noise.” In so doing, the Guidelines set criteria which are inconsistent with the EPA’s Industrial Noise Policy. Examination of noise data from the Capital Wind Farm confirms that the current Draft Guidelines will permit noise significantly above background level i.e. offensive noise which is likely to interfere unreasonably with a person’s health, comfort or repose.
- The base limit for wind farms should be 30 dB(A) when assessed under the worst case scenario. Testing establishes that this limit would be consistent with EPA guidelines for the protection of acoustic amenity in rural areas.
- The Guidelines are vague and inconsistent in relation to the assessment of and measurement during temperature inversions. This undermines the efficacy of the noise criteria.
- The use of the A-weighting filter is not sufficient to account for the audibility and annoying characteristics of wind farm noise. This is demonstrated with data obtained from the Capital Wind Farm, Woodlawn Wind Farm and Cullerin Range wind Farm.
- The guidelines do not specifically require full spectrum noise monitoring inside residential properties. Data obtained demonstrates that such monitoring is essential to reflect noise impact and specific noise characteristics.
- The Guidelines require more detailed acoustic analysis at the proposal stage to identify the effects of different weather scenarios. These scenarios are typically required for industrial noise assessments and in their absence, proper compliance monitoring is impossible.
- The measurement procedure in relation to specific noise characteristics describes measurements conducted over a 10 minute period. This does not permit identification of these characteristics which are associated with swish, modulation, discrete tones and low frequency noise. This is demonstrated with analysis of data from operating wind farms. Criteria in relation to amplitude modulation are uncertain.
- Examination of data demonstrates that compliance monitoring can only be effective with the provision of permanent noise monitoring within the wind farm, recording noise levels, wind speed and direction at receiver locations and recording wind speed and direction at hub height. The Guidelines do not, but should, provide for such permanent noise monitoring supplemented with temporary remote monitoring in real time to deal with complaints.
- The provision of permanent noise monitoring data together with real time presentation of the wind speed and direction at the hub, the power output and operational status of individual turbines must be provided in the public domain to permit independent compliance testing. There is no provision for this in the Draft Guidelines.
- Compliance procedures are ineffective. The Guidelines do not provide a clear indication of what triggers non-compliance. The specified effects of non-compliance are vague. There are no provisions requiring a cessation of operations if the wind farm is not compliant.
Download original document: “Review of NSW Draft Wind Farm Guidelines”
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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