Sonus, NSW Planning Guidelines Review February 2012
Sonus Pty Ltd
17 Ruthven Avenue
ADELAIDE SA 5000
NSW GOVERNMENT DEPARTMENT OF
PLANNING & INFRASTRUCTURE
DRAFT NSW PLANNING GUIDELINES DECEMBER 2011
Graph 1 – Background noise data analysis based on 24 hours
Graph 2 – Background noise data analysis based on night time only
Table 1 – Environmental noise criteria based on Graph 1 and Graph 2
Specific Noise Characteristics
Comparison with other jurisdictions
A review of the noise related aspects of the Draft NSW Planning Guidelines December 2011 (NSW 2011), released for public comment by the NSW Government’s Department of Planning and Infrastructure has been conducted.
The review includes a comparison against the relevant parts of the current assessment regimes in NSW, South Australia and Victoria. For clarity, wind farm development in NSW is currently assessed predominantly under the South Australian EPA Wind Farm Noise Guidelines 2003 (SA 2003). In South Australia, wind farms are assessed under the South Australian EPA Wind Farm Noise Guidelines 2009 (SA 2009) and in Victoria, are assessed under the New Zealand Standard NZS 6808:2010 Acoustics – Wind farm noise (NZS2010).
NSW 2011 introduces a “Gateway” process which is required in circumstances where turbines are proposed to be located within 2 kilometres of a dwelling that has not entered into an agreement regarding such a location.
The “Gateway” process requires a satisfactory environmental noise assessment (likely to be the subject of an independent review) to be prepared prior to the issue of the Director General’s Requirements and the subsequent initiation of the planning approval procedure.
Noise is often the most important factor in determining the separation distance between wind turbines and sensitive receivers. The assessment of noise therefore plays a significant role in determining the viability of and the size of wind farms.
Regulatory and objective certainty provides the ability to conduct a clear objective assessment that can be confirmed both during the development and operational phases of a wind farm project.
NSW 2011 will introduce the most onerous noise criteria and methodology of any of the current jurisdictional assessment regimes. Whilst the objective criteria are equivalent to SA 2003, the requirement to achieve the criteria when only considering the night time background noise levels will result in more onerous requirements. It is likely that separation distances between the closest turbine and the nearest non-associated dwelling for a typical wind farm will need to be in the order of 2 kilometres to comply with the criteria.
NSW 2011 will introduce a compliance checking procedure that requires complex methodologies and equipment to measure for amplitude modulation, tonality and low frequency characteristics. These measurements are not required under SA 2003 and justification for their inclusion as part of the compliance checking procedure is not provided. Regardless of the existence of justification or otherwise, the test methodology for the presence of amplitude modulation has the potential to be unworkable.
The “Gateway” process and the introduction of “Independent Reviews” will require clear and concise direction within NSW 2011 relating to the required scope and appeal rights of such investigations. Without such direction, these processes have the potential to introduce significant uncertainty and ambiguity into the process.
NSW 2011 provides an opportunity to conduct testing and establish agreed inputs to a noise model, which in turn, could reduce the ambiguity and uncertainty in both the analysis and compliance checking procedures compared to all other approaches.
In general terms, noise from a wind farm increases with wind speed up until the “rated power” (electrical output capacity) of the particular turbine is achieved. At levels of rated power, noise outputs remain relatively constant and may even reduce at higher wind speeds. Increases in noise output generally occur in conjunction with an increase in the background noise level, ie. as wind speed increases, background noise levels also increase due to increased wind in foliage and other local structures.
The dual noise generation profiles provide a masking effect for wind farm noise such that at higher wind speeds it is generally unlikely that wind farm noise is audible at required separation distances.
The methodology that underpins wind farm noise standards and guidelines in Australia and New Zealand recognises the positive correlation between wind turbine and background noise and establishes a base noise limit that generally applies at lower wind speeds when the background noise is relatively low and will not mask the sound of an operating turbine. The base noise limit is then adjusted to account for increases in background (masking) noise as the wind speed increases.
The base noise limit is established to protect the amenity of the surrounding community, ie to ensure it is not adversely affected in low background noise environments. In higher wind speeds, as the masking effect of wind in the trees and over structures increases, the noise limit also increases.
The base noise level requirement varies between 35 and 40 dB(A) depending on the Standard or Guideline being used. The base noise level can also vary within the Standard or Guideline depending on certain circumstances, as is in the case of the NZS2010 and the 2009 South Australian EPA Wind Farm Guidelines.
NSW 2011 provides a base noise level of 35 dB(A), which represents a low (onerous) noise level in an environmental noise context. It is below the World Health Organisation’s recommended guideline value of 40 dB(A) for general sleep disturbance effects and below both of the contemporary approaches in South Australia and Victoria for comparable development in general farming areas.
The base noise level requirements also need to be considered in the context of the ambient environment. Wind farms are generally located in a rural environment, where the associated planning system envisages and promotes activity associated with primary industry. Wind farms are also inherently located in areas of high wind speed which coincide with high background noise levels.
NSW 2011 requires both the day and night time background noise levels to be considered when adjusting the base noise level limit to account for increases in background (masking) noise as the wind speed increases. This is a modification to SA 2003, which is based on a 24 hour background noise level. As the background noise levels at night are often lower than during the day, the effect will be to limit the adjustment made to the base line noise limit. This will result in more onerous objective criteria.
To assist in considering the above, a review of typical background noise level data has been made to generate the two graphs shown below. Graph 1 uses the current SA 2003 regime of using all data in a 24 hour period, and Graph 2 uses the proposed NSW 2011 regime of considering only the day or night period. The criteria for both regimes are then summarised in Table 1.
(See downloadable document at the base of this page for graphs and charts.)
The criteria under the NSW 2011 are more onerous for this example.
The effect of the more onerous criteria has been considered for an example wind farm layout. Compliance with the SA 2003 criteria as provided by Graph 1 could occur at a separation distance in the order of 1600m. Compliance with the NSW 2011 criteria as provided by Graph 2 could occur at a separation distance in the order of 2000m.
The required separation distances will be specific to a wind farm proposal. In some circumstances, such as where there is a consistent wind shear during the day and night, it is expected that the SA 2003 and NSW 2011 will deliver similar results.
The UK Department of Trade and Industry1 have prepared guidelines that separate the background noise data into day and night periods. The baseline noise level for the higher night time period is increased to 43 dB(A) to account for “sleep disturbance effects” rather than impacts on external amenity. A reason SA 2003 does not require the assessment procedure to be separated into day and night periods is the onerous nature of the approach relative to the potential onset of sleep disturbance effects.
Specific Noise Characteristics
The Guidelines have been developed with the fundamental characteristics of wind turbine noise taken into consideration, including swish (modulation), discrete tones and low frequency content.
The Guidelines provide procedures for assessing excessive levels of the above characteristics. The Guidelines appear to require these test procedures to be conducted as part of the compliance checking for each of these characteristics.
This testing is required for these characteristics without:
- evidence of the characteristics being a regular and concerning feature of wind farms;
- an established amplitude modulation test regime to accurately identify that particular characteristic; and
- identifying the levels at which the characteristics would become a concern.
The Guidelines do enable the tests to be conducted at an intermediate location for amplitude modulation and low frequency noise, which can assist to a degree from a technical perspective. However, the tests introduce significant additional constraints into an already complex compliance checking procedure, without evidence for their need.
In addition, it is likely that the test for amplitude modulation will not enable a definitive result when considering the background noise environment in the vicinity of a wind farm.
In addition to the main issues above, the following provides specific feedback on each identified element within NSW 2011:
- NSW 2011 recommends a condition of consent that enables an independent review be conducted at a neighbouring property, subject to the Director General being satisfied that such a review is warranted. The review is to be commissioned by the proponent. The factors relating to whether such a review is warranted should be contained within NSW 2011 to ensure a consistent, equitable and transparent approach to such reviews;
- NSW 2011 notes that sub-stations are to be considered separately under the NSW Industrial Noise Policy (INP). There is a conflict in the cumulative noise section of NSW 2011 where it states the turbines and sub-stations should be accounted for together, rather than under separate and unique regimes. The inconsistency should be clarified;
- The method of considering cumulative impacts results in a “first in best dressed” approach to development. That is, a second wind farm in a region would be subject to significantly more onerous noise requirements than the first approved in that region. This is consistent with NZS 2010 but conflicts with both versions of the SA Guidelines. SA 2003 and SA 2009 allow each wind farm to be designed to achieve the objective criteria without adjustment for the presence of other wind farms. This is to provide equity for development and is enabled because of the onerous nature of the approach.
- The measurement locations section of NSW 2011 requires further information on siting of noise loggers. The general principles of locating the logger are not explicit;
- The use of the term “extraneous noise” will cause ambiguity within NSW 2011 without specific and detailed definition, particularly given that the main measurement descriptor (being the LA90) inherently excludes short term and / or intermittent “extraneous” noise sources. The current definition which relates to the difference between the LA90 and LAeq of more than 5 dB(A) could result in typical events, such as wind in the trees, being excluded from the data set as an “extraneous” event;
- The term “undue wind turbulence” is used with respect to the wind mast monitoring location. Such a term will need to be clearly defined to ensure appropriate locations of wind masts result;
- Noise logging equipment may be Class 2 provided the noise floor of the equipment is at or less than 20 dB(A). This will ensure appropriate equipment is used for the background noise logging regime;
- Care needs to be taken with the use of the LAeq descriptor, given that the equivalent noise levels from wind in the trees can be substantially greater than the equivalent noise levels from the turbines. Whilst this is acknowledged in some areas, it is not explicit and consistent throughout the document;
- The method to convert the sound power level data for a turbine from 10m to hub height could be provided to ensure consistency;
- It should be clear that the tonality measurement procedure is conducted at the residence and inclusive of background and ambient noise;
- The trigger point for the application of the penalty for tonality for the scenario of its presence only under “certain wind speeds and directions” requires clarification. It appears to relate to the 10% (or “regular exceedance”) rule, however, that is not clear, and in the absence of that rule, could be triggered should tonality be found in any 10 minute data set. In addition, further clarification will be necessary with respect to data analysis – for example, if the tone is identified at 4.4m/s wind speed, is the penalty to be applied to all data between 3.5 and 4.5m/s or between 3 and 4m/s;
- The low frequency criterion established in NSW 2011 is expected to be exceeded by the ambient noise environment, from sources such as wind in trees. Therefore, the ability to measure at an intermediate distance and apply “relevant geometric spreading techniques” is an essential element. The “techniques” should be provided in NSW 2011 given the expected reliance on the method;
- There are no data in NSW 2011 that suggests fundamental modulation only occurs at a modulation depth of less than 4 dB(A) and that excessive modulation occurs at 4 dB(A) or greater. Notwithstanding the lack of a basis for such a test, it has not been established that a reliable measurement of a modulation of 4 dB(A) can be determined in a typical wind farm background noise environment. The amplitude modulation test has been developed and implemented without basis and has the potential to be unworkable in the field;
- The trigger point for the application of the penalty for amplitude modulation for the scenario of its presence only under “certain wind speeds and directions” requires clarification. It appears to relate to the 10% (or “regular exceedance”) rule, however, that is not clear, and in the absence of that rule, could be triggered should modulation be found in any 10 minute data set.
Comparison with other jurisdictions
The provisions of NSW 2011 are compared against:
- SA 2003 (the current NSW guidelines);
- SA 2009 (the current SA guidelines); and
- NZS2010 (the current Victorian guidelines).