Resource Documents: Oceania (1 items)
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Author: Hansen, Kristy; Nguyen, Phuc; Zajamšek, Branko; Catcheside, Peter; and Hansen, Colin
ABSTRACT – The presence of amplitude modulation (AM) in wind farm noise has been shown to result in increased annoyance. Therefore, it is important to determine how often this characteristic is present at residential locations near a wind farm. This study investigates the prevalence and characteristics of wind farm AM at 9 different residences located near a South Australian wind farm that has been the subject of complaints from local residents. It is shown that an audible indoor low-frequency tone was amplitude modulated at the blade-pass frequency for 20% of the time up to a distance of 2.4 km. The audible AM occurred for a similar percentage of time between wind farm percentage power capacities of 40 and 85%, indicating that it is important that AM analysis is not restricted to high power output conditions only. Although the number of AM events is shown to reduce with distance, audible indoor AM still occurred for 16% of the time at a distance of 3.5 km. At distances of 7.6 and 8.8 km, audible AM was only detected on one occasion. At night-time, audible AM occurred indoors at residences located as far as 3.5 km from the wind farm for up to 22% of the time.
Kristy L. Hansen, Phuc Nguyen, College of Science and Engineering, Flinders University, Tonsley, Australia
Branko Zajamšek, Peter Catcheside, College of Medicine, Flinders University, Bedford Park, Australia
Colin H. Hansen, School of Mechanical Engineering, University of Adelaide, Australia
Journal of Sound and Vibration 455 (2019) 136–149. doi: 10.1016/j.jsv.2019.05.008
Download original document: “Prevalence of wind farm amplitude modulation at long-range residential locations”
Author: Cooper, Steven
The issue of an updated noise guideline for wind farms in South Australia represents the third (public) attempt at the Environment Protection Authority (EPA) to address wind turbine noise and unfortunately still contains significant errors and omissions as to to fundamental requirements with respect to the protection of the amenity of residents in proximity to wind farms.
Despite complaints from residents and documentation in relation to such complaints, the EPA have not established appropriate criteria to protect the acoustic amenity of residents. …
The guidelines do not identify what level of noise, or what noise characteristics, will result in sleep disturbance. Assuming that most people will sleep indoors, then Section 2.3 identifies that sleep disturbance is likely to be considered inside as an unreasonable interference that in turn could create an adverse health impact. Section 2.3 is silent on what is a sufficient outdoor amenity to not create an adverse health impact. … There is no information to identify what wind turbine noise levels and characteristics create and adverse impact for hosts or non-hosts. … Without this material provided in the noise guidelines then there is absolutely no way that any environmental assessment can be undertaken for a wind farm and identify that there will be no adverse noise impact. … There is no material to support the limits specified in the guidelines, and in light of no dose-response data for wind turbines, the matter of not identifying the precautionary principal in creating a noise guideline in relation to wind turbines is not acceptable.
In relation to fulfilling the ethical and moral obligations of acousticians to rural communities in proximity to wind farms, research has been conducted by multiple researchers including Professor Colin Hansen, Associate Professor Con Doolan, & Dr Kristy Hansen at Adelaide University & Flinders University, Dr B Thorne, Mr L Huson and the author into what constitutes the acoustic signature of wind turbines and how it is impacting upon people. The Adelaide University researchers conducted almost all of their research at Waterloo Wind Farm in South Australia, and have published a text book as well as multiple peer reviewed published papers. There is no reference to any of that material in the bibliography to the draft guidelines … In addition to the failure of the SA EPA to establish the acoustical basis of the core objectives and how the nominated levels will protect the community for adverse noise or health impacts there a technical issues in the guidelines that question the technical capability of the SA EPA to fulfil their obligations to protect the rural community from adverse noise impacts from wind turbine installations.
There is general agreement in acoustic Standards that there is a distinct different degree of sensitivity to noise by residential receivers during the night to that in the day. There are many Acoustic Standards throughout the world in relation to industrial noise and transportation noise where there is a different weighting (for different acoustic descriptors) applied to noise events that occur in the night-time period when compared to the daytime period. …
The concept for wind turbines of using a generic criteria based upon 24-hour measurements would appear to be inconsistent with general environmental assessments, in that there is an expectation of lower background levels and therefore lower criteria for the night time periods. Background levels at night are typically lower than in the day. Yet the draft guideline does not acknowledge this fact by providing different criteria.
Generally for a wind farm application, with respect to wind data monitoring of the wind for a proposed wind farm is undertaken over a number of years. Therefore, the concept of utilising two weeks of noise data for establishing criteria for a wind farm would appear to be inadequate and not appropriately considered by the EPA.
The difference in prevailing wind for a site or receiver location for the different seasons of the year may be significant in terms of both the assessment of the background level and the predicted noise levels. Such differences are not appropriately reflected in a regression averaging technique based upon hub height wind speeds without any identification of wind direction or seasons.
In the determination of noise criteria for other noise sources such as industry for transportation, the use of dose response curves determines criteria based around 10% of the population seriously or highly affected.
One concept presented in New South Wales by the EPA and Department of Planning is to establish criteria to protect 90% of the population 90% of the time and in that regard ambient background level is expressed in terms of the lowest 10 percentile of the background levels.
It is upon that lowest 10 percentile background level upon which in NSW the background +5 dB(A) limit as a general criterion is based. …
Section 4.7 (Annoying characteristics) repeats the previous errors (in the current and original version of the guideline) in relation to infrasound and clearly an inadequate literature research that indicates that is not a problem.
The suggestion in Section 4.7 that amplitude modulation or low frequency noise is not expected to impact upon receivers during a substantial fraction of the year is incorrect. …
Amplitude modulation by definition is the variation in the level of a carrier frequency where the variation in the level of that carrier frequency (described as modulation) occurs due to a much lower frequency. …
For a wind turbine when one is utilising the correct terminology, amplitude modulation can be related to the output shaft speed of the gearbox (where that tone is the carrier, as a clear and distinct tone) that is modulated at the rate of the blade pass frequency. Depending upon the turbine model the carrier frequency may be at for example, 25.5 Hz, 26 Hz or 31.5 Hz. A narrowband frequency analysis of the signature reveals side bands (to the gearbox output shaft frequency) that clearly satisfy the definition of amplitude modulation [link].
However, the audible noise associated with the “swish” or “thumping” noise is not amplitude modulation (by definition) but is a “modulation of the sound” as identified in the New Zealand Standard as a special audible characteristic. One would have expected the SA EPA to have understood the difference between amplitude modulation and modulation of the sound.
The use of the dB(A) level cannot, by definition be considered as a single frequency because it is a result of multiple frequencies. The dB(A) level can be seen to be modulated at the rate of the blade pass frequency. Therefore, the modulation (variation) of the dB(A) level cannot be called amplitude modulation. The periodic variation on the amplitude of the dB(A) is a modulation of the dB(A) level, where the modulation occurs at an infrasound rate. …
Additionally, it must be noted that determining “compliance” by use of a L90 average level would not account for the modulation of the acoustic signal. The time signature of a wind turbine identifies a series of pulses which occur at the blade pass frequency. The blade pass frequency is in the order of 0.86 Hz for a three bladed turbine operating at 17 rpm.
Therefore, there are questions as to whether infrasound as a concept of sound itself is generated by wind turbines [link1; link2]. As such the concept of audibility or effects from infrasound as suggested in the guideline may not be appropriate. The threshold of audibility for a tone is different to that of a pulse, especially in the infrasound region [link]. Research work and investigations undertaken by the author (by testing conducted in a chamber that could produce infrasound pure tones down to 1 Hz) identified that there is a difference in terms of the perception of infrasound for pure infrasound tones on a constant basis versus pulsations. There is also a hysteresis effect in the thresholds (for both sensitivity and hearing) when increasing the level of infrasound versus decreasing the level [link]. Additional work undertaken by the author has identified the provision of signals recorded in houses in proximity to wind farms and specifically using filters to prohibit any sound below 40 Hz into the speakers, to find that digital frequency analysis of the signal will show the presence of a signature in the infrasound region by way of the incorrect analysis of the pulsations, when in fact there is no infrasound present [link]. …
The suggestion in Section 4.7 of the draft guideline that annoying characteristics are not fundamental to a typical well-maintained wind farm is incorrect. In the UK there have been efforts to define “excessive amplitude modulation” in light of the increase in annoyance that identifies the above SA EPA claim of annoying characteristics is incorrect. Often residents complain that they hear (generally inside the dwelling but also external to the dwelling) on a continuous basis a low frequency noise when the turbines are operating, with the description typically expressed as a plane that never lands.
The development of wind farms in South Australia has resulted in the creation of a new industrial noise source that gives rise to disturbance to rural residents.
With the benefit of hindsight, it is apparent that the guidelines introduced by the South Australian EPA were not based upon actual wind turbine noise but on criteria for other noise sources without identifying the differences between those established noise source sources and wind turbine noise. Over the ensuring period the size of wind turbines has increased and so has the impact. Therefore one questions the relevance of original work on wind turbine noise carried out in Europe on turbines with significantly lower capacity.
From the outset, the South Australian wind farm guidelines had failed to provide material that identifies how the objectives of the guidelines are satisfied, by not identifying what acoustic impacts occur or adverse health impacts that occur as a result of the operation of wind turbines.
On a statistical basis, the number of complaints from communities in proximity to wind turbines is well above the norm and as such cannot be ignored by any regulatory authority if acting to protect the amenity of residents.
The principal issue that the author has experienced in attending residential properties with respect to wind farms is that residents report sleep disturbance. There appears to be a deterioration over time for some people that are impacted. It is noted that not all people are impacted by wind turbines which is compatible with an analogy for seasickness. …
There is often an excuse provided that there are no studies to show that wind farms create health impacts, which can also be said in the reverse case that there are no studies to show there are no health impacts. Because there is a lack of studies.
Work undertaken by the author has identified that in a laboratory situation persons who have become sensitised to wind turbines can detect the presence of a wind turbine signal even though it is inaudible [link]. I am advised by persons who have been adversely affected by wind turbines to the point of having to relocate from their properties (permanently or regularly) and who have recently participated in testing undertaken by Flinders University that in terms of the sleep study they have experienced disturbed sleep.
Further work by the author in relation to the investigation of fluctuations (that is not just restricted to wind turbine noise) reveals that the presence of excessive modulation, which occurs on a regular basis from wind turbines, gives rise to a greater level of annoyance which should be added to the A-weighted levels with respect to wind turbine noise [link].
Download original document: “South Australia Wind Farm Guidelines Consultation”
Author: Asten, Heidi; Tarasenko, Ellen; and Ellicott, Thomas
Wind energy facility proponents should take note of recent developments in the regulation of noise impacts from wind energy facilities in Victoria, which signal increased scrutiny of noise impacts from operations. This includes:
- South Gippsland Shire Council’s finding of statutory nuisance under the Public Health and Wellbeing Act 2008 (Vic) (PHW Act) in relation to the Bald Hills Wind Farm;
- The impending introduction of the general environmental duty in relation to noise under the Environment Protection Act 2017 (Vic); and
- The Victorian Civil and Administrative Tribunal’s (VCAT) consideration of the application of the high amenity noise limit under the New Zealand Standard Acoustics – Wind farm noise NZS 6808:2010 (2010 NZS) to the Farming Zone in Naroghid Wind Farm Pty Ltd v Minister for Planning  VCAT 800 (3 June 2019) (Naroghid).
These developments highlight the significance of proactive and robust management of noise impacts for both existing and proposed wind energy facilities.
South Gippsland Shire Council’s investigation of Bald Hills Wind Farm under the PHW Act
In March 2019, the South Gippsland Shire Council (Council) determined that the Bald Hills Wind Farm had caused nuisance under the PHW Act as a result of noise from the operation of its wind turbines. The decision followed a Supreme Court of Victoria ruling requiring the Council to engage an independent health assessor to consider the complainants’ concerns.
In reaching its finding that a nuisance had been caused, the Council attributed weight to noise logs, and evidence of health impacts provided by the complainants. Significantly, the decision was made notwithstanding reported compliance with the noise conditions of the planning permit for Bald Hills Wind Farm. The lack of directly comparable data correlating timing, location and nature of noise emissions between the formal noise compliance monitoring and the noise complaints presented some challenges to all parties.
The decision is the first finding of nuisance under the PHW Act in relation to noise from the operation of wind turbines. The decision has not been appealed, and may set a precedent for other local government authorities in PHW Investigations. Our key observations in relation to the decision are:
- Compliance with planning permit conditions does not necessarily preclude a finding of nuisance under the PHW Act in relation to noise from wind energy facilities;
- Evidence of impacts on sleep, and corroboration by an independent expert of high levels of audible noise from wind turbines within dwellings was central to the finding of nuisance;
- Wind energy facility proponents may wish to consider whether their post-construction monitoring addresses consideration of any noise complaints they receive; and
- Wind energy facility operators will need to engage with complainants and councils if nuisance complaints are made under the PHW Act.
The new general environmental duty
The Environment Protection Act 2017 (Vic) will require wind energy facilities to comply with a new ‘general environmental duty’ (GED) when it comes into effect (along with a whole suite of other reforms), currently expected to be in mid-2020. The GED will operate separately from planning permit requirements, and from noise nuisance considerations, including under the PHW Act.
The GED will require that ‘a person who is engaging in an activity that may give rise to risks of harm to human health or the environment from pollution or waste must minimise those risks, so far as reasonably practicable’. Significantly, ‘human health’ is defined to include ‘psychological health’. The GED will require management of noise impacts from operations, given that the definition of ‘pollution’ includes noise pollution. A person commits an offence if they contravene the GED in the course of conducting a business undertaking.
The Environment Protection Authority (EPA) will have primary responsibility for regulating the GED. However, third parties may also bring actions for breach of the GED in some circumstances, and seek civil and compensation orders in respect of injury, loss or damage resulting from a contravention.
Wind energy facility operators should consider:
- What are the risks of harm to human health or the environment from operation of the wind farm, including in respect of noise?
- To what extent can the risk of harm be avoided, and has this been done so far as reasonably practicable?
- To what extent can the risk of harm be mitigated, and has this been done so far as reasonably practicable?
- To what extent are their procedures to engage with the local community effective in resolving issues or complaints that may arise during operation?
The EPA is yet to release detailed guidance as to how it intends to regulate the GED, including in the context of wind energy facilities. Once released, such guidance will be an important means of understanding the EPA’s likely approach. The EPA will also be releasing subordinate legislation under the new regime, including environmental reference standards which will regulate noise emissions and replace existing State environment protection policies.
The Naroghid decision
In Naroghid, VCAT considered a planning permit application for a 12 turbine wind energy facility in Corangamite, in the vicinity of Cobden.
VCAT refused to grant a permit for the wind energy facility on a number of grounds. However, of broader relevance to the industry, the decision provides a discussion of the application of the high amenity noise limit under the 2010 NZS to the Farming Zone. The high amenity noise limit under the 2010 NZS applies a limit of 35dB or background +5 dB, as opposed to 40dB or background +5 dB in other areas under the 2010 NZS.
While the Tribunal did not make a final ruling on the issue, it expressed the view that the high amenity noise limit should apply to non-stakeholder dwellings in the Farming Zone. The discussion on this point is contrary to the finding in another VCAT decision in Cherry Tree Wind Farm Pty Ltd v Mitchell SC & Ors (Includes Summary) (Red Dot)  VCAT 521 that the high amenity noise limit does not apply in the Farming Zone. While the Tribunal in Naroghid agreed that the planning scheme is the relevant ‘plan’ relevant to application of the NTS 2010 in this context, the Tribunal’s discussion went on to attach particular weight to EPA Publication 1411 Noise from Industry in Regional Victoria (October 2011). Based on the approach to noise amenity in NIRV (a reference document in the Planning Scheme which is currently being updated), the Tribunal suggested that a high amenity noise limit should be applied to the Farming Zone.
While the discussion in Naroghid is not authority for the application of the high amenity noise limit to the Farming Zone, wind energy facility proponents may wish to consider noise compliance risks at dwellings within the 35dB noise contour.
Herbert Smith Freehills LLP – Heidi Asten, Ellen Tarasenko and Thomas Ellicott
August 30 2019 lexology.com
Author: Thorne, Bob; and Noise Measurement Services
Bald Hills Noise Monitoring PTR Data: “The 40 dB(A) noise limit is exceeded on the days coloured ‘peach’/’transparent red’ (PTR)”
- May 2018 (11.31 MB) [alt. link]
- June 2018 (22.01 MB) [alt. link]
- July 2018 (10.88 MB) [alt. link]
- August 2018 (14.50 MB) [alt. link]
- September 2018 (12.87 MB) [alt. link]
- October 2018 (11.87 MB) [alt. link]
- November 2018 (10.88 MB) [alt. link]
- December 2018 (6.32 MB) [alt. link]
- January 2019 (5.35 MB) [alt. link]
- March 2019 (6.31 MB) [alt. link]
Sample noise event charts (colour dots represent noise complaints):