SP0372.R1 Dalveen Wind Farm - Noise Assessment Impact Assessment Dalveen Wind Farm Dalveen, QLD...

Noise Impact Assessment

Dalveen Wind Farm

Dalveen, QLD

Document No. SP0372-0, Revision 1

Prepared for:

Muirlawn Pty Ltd

PO Box 5816

West End QLD 4101

20 May 2013


Dalveen Wind Farm Dalveen, QLD

SP0372.R1 Dalveen Wind Farm - Noise Assessment.docx ii Revision 1 - 20 May 2013

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1 20/05/13 Final DB MT

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SP0372.R1 Dalveen Wind Farm - Noise Assessment.docx iii Revision 1 - 20 May 2013

Executive Summary This report has been prepared by Savery & Associates Pty Ltd for Muirlawn Pty Ltd to prepare

an acoustic assessment of the noise impacts associated with the proposed Dalveen Wind Farm in

Queensland.

The purpose of the proposed works is to assess the proposed wind farm for compliance with the

relevant noise limits at sensitive receptors in accordance with Council’s requirements in their

request for information dated 21 November 2012.

Noise from the proposed wind farm has been predicted to residences in the vicinity based on the

ISO 96131 noise propagation model and sound power level data provided by the proposed wind

turbine generator manufacturer. The applicable environmental noise criteria were determined

based on the relevant guidelines and background noise monitoring conducted at three residences

in the vicinity of the wind farm. The locations of the turbines and relevant receivers are

provided in Appendix A.

Background infrasound noise measurements have been conducted at one of the residences south

of the proposed wind farm site. These measurements provide an indication of the current

infrasound ambient noise environment at the proposed wind farm location. After the wind farm

is commissioned, these measurements can be compared with the operational infrasound levels.

The assessment concludes that the proposed 8 wind turbines will comply with the derived noise

criteria at the nearest noise sensitive receptors. An additional turbine (T8) would not meet the

criteria at House 1, but could be considered if arrangements were made for the removal of this

sensitive receptor.

The derived 37dBA LAeq criterion at the nearby receptor locations can be achieved with the

investigation of suitable noise control measures including the recommended noise attenuation

measures.

Construction noise impacts can be minimised using the Construction Noise Management Plan.



SP0372.R1 Dalveen Wind Farm - Noise Assessment.docx iv Revision 1 - 20 May 2013

Contents 1.0 INTRODUCTION ..................................................................................... 6

2.0 SITE LOCATION AND SURROUNDING AREA ................................ 6

3.0 PROPOSED DEVELOPMENT ............................................................... 7

3.1 Site Construction ....................................................................................... 7

4.0 NOISE ASSESSMENT CRITERIA ........................................................ 9

4.1 Environmental Values to be Protected ...................................................... 9 4.2 Quantitative Noise Policy .......................................................................... 9 4.3 Noise Limits for Specific Sources ........................................................... 10 4.4 SA EPA Wind Farm Environmental Guidelines ..................................... 10 4.5 Low frequency noise criteria ................................................................... 10 4.6 Infrasound noise criteria .......................................................................... 11 4.7 Backup Diesel Generator Criteria ........................................................... 12 4.8 Construction Noise Criteria ..................................................................... 12

5.0 BASELINE NOISE MONITORING ..................................................... 14

5.1 Study Methodology ................................................................................. 14 5.2 Analysis of Baseline Records .................................................................. 16 5.3 Wind Turbine Noise Criteria ................................................................... 17

6.0 NOISE MODELLING ............................................................................ 19

6.1 Methodology ........................................................................................... 19 6.2 Source Sound Power Level Data ............................................................. 19 6.3 Noise Model Scenarios ............................................................................ 20

7.0 IMPACT ASSESSMENT ....................................................................... 21

7.1 Assessment of Proposed Wind Turbines ................................................. 21 7.2 Assessment of Backup Diesel Generators ............................................... 24 7.3 On-site and Off-site Construction Assessment ........................................ 25

8.0 RECOMMENDATIONS ........................................................................ 27

9.0 CONCLUSIONS ...................................................................................... 28

APPENDIX A - FIGURES ............................................................................. 29

APPENDIX B - MODELLED SOUND POWER LEVELS ........................ 34

APPENDIX C - BACKGROUND NOISE LEVEL SUMMARY ............... 36

C.1 Marini House – External ......................................................................... 36 C.2 Marini House – Internal Infrasound Measurements ................................ 41 C.3 Savios House ........................................................................................... 49 C.4 Site 3 ........................................................................................................ 53

APPENDIX D - ACOUSTIC TERMINOLOGY AND UNITS OF MEASUREMENT ............................................................................................. 57

D.1 Abbreviations .......................................................................................... 57 D.2 Glossary of Terms ................................................................................... 58 D.3 Human Response to Sound ...................................................................... 59 D.4 Sensitivity to Sound Level ...................................................................... 59 D.5 Sensitivity to Sound Frequency ............................................................... 60 D.6 Sound Level Meters and A-weighting ..................................................... 60



SP0372.R1 Dalveen Wind Farm - Noise Assessment.docx v Revision 1 - 20 May 2013

D.7 Tonality and Impulsivity Adjustments to Measured Levels .................... 61 D.8 Response Time ........................................................................................ 61 D.9 Descriptors for Environmental Noise Assessment .................................. 61



SP0372.R1 Dalveen Wind Farm - Noise Assessment.docx 6 Revision 1 - 20 May 2013

1.0 Introduction

This report has been prepared by Savery & Associates Pty Ltd for Muirlawn Pty Ltd to prepare

an acoustic assessment of the noise impacts associated with the proposed Dalveen Wind Farm in

Queensland.

The purpose of the proposed works is to assess the proposed wind farm for compliance with the

relevant noise limits at sensitive receptors in accordance with Council’s requirements in their

request for information dated 21 November 2012. Included in Council’s letter was the request

for:

A detailed noise assessment, including the recording of background noise measurements

and infrasound levels. Details should also be provided with regards to monitoring

methods once operational.

Noise from the proposed wind farm has been predicted to residences in the vicinity based on the

ISO 9613 noise propagation model and sound power level data provided by the proposed wind

turbine generator manufacturers. The applicable environmental noise criteria were determined

based on the relevant guidelines and background noise monitoring conducted at three residences

in the vicinity of the proposed wind farm. The locations of the turbines and relevant receivers

are provided in Appendix A.

Background infrasound noise measurements have been conducted at one of the residences south

of the proposed wind farm site. These measurements provide an indication of the current

infrasound ambient noise environment at the proposed wind farm location. After the wind farm

is commissioned, these measurements can be compared with the operational infrasound levels.

2.0 Site Location and surrounding area

The Dalveen Wind Farm is proposed to include several wind turbine generators (WTG’s) on

rural land approximately 16km north of Stanthorpe in Queensland. The site address is Lot 56

Rabbit Fence Road, and incorporates Lot 56 on CP 341446 and Lot on RP 84055, Parish of

Rosenthal, County of Merivale. The area of the development application is 438 ha.

There are a number of residential properties located near the proposed site, as shown in Figure 4

in Appendix A.




3.0 Proposed Development

The project at Dalveen will include the construction of the following, which are illustrated on

Figure 5.

Eight wind turbines, each with a power generation capacity of 1.7MW. It should be

noted that Figure 5 also includes an additional turbine (T8) to the eight assessed, which

is excluded from this assessment. Construction of this turbine would only be possible

with the removal of Receptor “House 1” as a sensitive receptor;

Solar panels in four arrays, with a 6MW capacity;

Backup emergency power generation in the form of four to six diesel generators;

Site infrastructure, such as maintenance buildings; roads; and electricity.

The proposed development is intended as a backup/emergency power generation facility for the

local area, for use when the main 110kV power transmission line is undergoing essential

maintenance and the 33kV supply falls short of the power requirements for the local

Stanthorpe/Pozieres region.

In the short-term, this is anticipated to require the use of diesel generators during the daytime

only, while the 110kV power transmission line is being upgraded and the construction of the

wind farm and solar collection is being undertaken.

Once the 110kV power transmission line is upgraded, use of the power generation from the site

will only be required in the event of an outage of the 110kV line, which would not be expected

to occur more than four times per year, for a nominal six hours at a time. For more than 60% of

a typical day, this power capacity would be provided by the wind turbines and solar array. The

remaining 40% of the time would require augmentation of the supply power using the diesel

generators.

The 4 events per year would constitute an emergency for the region in that major rotational load

shedding would be required. Currently the network is operating without sufficient alternate

power generation and the diesel backup is urgently required to allow for the above mentioned

essential maintenance and redundancy.

3.1 Site Construction

Construction of the wind turbines, solar array, generators and associated infrastructure is

expected to include the following activities:

civil works, including site levelling and compaction (utilising typical earthmoving equipment, such as scrapers, graders, excavators, vibratory rollers, front end loaders, backhoes, etc);

excavation and foundation construction (utilising backhoes, mobile cranes, generators, powered hand tools, concrete trucks, concrete pumps, welders, etc);

installation of site services;




building and plant structural erection, plant and equipment installation and fitout (utilising cranes, trucks, scissor-lifts, generators, powered hand tools, welders, etc); and

use of haul trucks to provide raw materials.




4.0 Noise Assessment Criteria

4.1 Environmental Values to be Protected

The Queensland Environmental Protection (Noise) Policy 2008 (EPP (Noise)) identifies the

environmental values to be enhanced or protected within the state of Queensland as –

the qualities of the acoustic environment that are conducive to protecting the health and biodiversity of ecosystems; and

the qualities of the acoustic environment that are conducive to human health and wellbeing, including by ensuring a suitable acoustic environment for individuals to do any of the following -

sleep;

study or learn;

be involved in recreation, including relaxation and conversation; and

the qualities of the acoustic environment that are conducive to protecting the amenity of the community.

4.2 Quantitative Noise Policy

The EPP (Noise) defines “Acoustic quality objectives” for the environment that are conducive

to human health and wellbeing, including the ability for individuals to sleep, study, relax or

converse. The acoustic quality objectives relevant to residential locations are reproduced below

in Table 1 for reference. However the Explanatory Notes to the EPP (Noise) advises, that these

objectives relate to the all-encompassing noise environment, and should not be used as emission

limits for individual industries or noise sources.

Table 1: EPP (Noise) Acoustic Quality Objectives for Residential Dwellings

Part 4 Section 10 of the EPP (Noise) defines the “management intent for an activity involving

noise” as follows:




4.3 Noise Limits for Specific Sources

For simple and common sources of noise disturbance in the community (e.g. noise from

regulated devices, domestic or commercial air-conditioning systems) the acoustic values are

protected by prescribed noise offences defined within the Queensland Environmental Protection

Act 1994 (EP Act)(updated 1 January 2009).

Queensland does not presently have noise criteria for wind farms. Discussions with the

Department of Environment and Heritage Protection have confirmed that it is acceptable to use

the methodology for setting noise emission limits to protect acoustic environmental values as

detailed in the South Australian Environment Protection Authority’s Wind Farms –

Environmental Noise Guidelines (the SA Guidelines).

4.4 SA EPA Wind Farm Environmental Guidelines

The SA Guidelines state:

The predicted equivalent noise level (LAeq,10), adjusted for tonality in accordance with these

guidelines, should not exceed:

35dB(A) at relevant receivers in localities which are primarily intended for rural

living1; or

40dB(A) at relevant receivers in localities in other zones; or

the background noise (LA90,10) by more than 5dB(A);

whichever is the greater, at all relevant receivers for wind speed from cut-in to rated power of

the WTG and each integer wind speed in between.

4.5 Low frequency noise criteria

Where low frequency noise causes concern to residents inside a house it would be desirable to

conduct the low frequency noise assessment using internal noise levels. In practice, however, an

internal noise level cannot be predicted accurately due to standing waves and resonances

1 A ‘rural living’ zone is a rural−residential ‘lifestyle’ area intended to have a relatively quiet amenity. The area should not be used for primary production other than to produce food, crops or keep animals for the occupiers’ own use, consumption and/or enjoyment. The noise amenity should be quieter than in an urban−residential area.




associated with typical small room dimensions of residential dwellings and access to internal

spaces for assessment is not always available. The Environmental Approval conditions

generally provided for industrial projects set an internal noise limit of 50dBZ and a difference of

no greater than 15dB between dBA and dBZ levels assessed inside a dwelling. These limits are

based on the DEHP Draft Ecoaccess Guideline Assessment of Low Frequency Noise.

More practical low frequency noise limits which are typically applied to industrial

developments require noise levels outside a sensitive receptor to be below 60dBC and the

difference between the internal A-weighted and C-weighted noise levels to be no greater than

20dB2.

Other research suggests a simple method for determining whether a noise level is likely to cause

low frequency noise annoyance due to external or internal noise levels, is to subtract the A-

weighted overall noise level from the C-weighted overall noise level. If the difference between

the two levels is greater than 20dB then the noise is described as being “unbalanced” and low

frequency noise annoyance may result.3

Due to the complexities of estimating internal noise levels, the assessment will be undertaken

using the comparison of the external A-weighted and C-weighted noise levels with the 60dBC

overall level and a difference in A-weighted and C-weighted noise levels being no greater than

20dB.

4.6 Infrasound noise criteria

Noise at frequencies below 20 Hz is considered to be infrasound (ISO: 7196:19954). These low

frequencies can still be audible to humans at sufficiently high levels. The level at which the

frequency is audible to the human ear is described as the hearing threshold, which has been

determined down to frequencies as low as 4 Hz (Watanabe & Møller, 19905). In general, the

lower the frequency the higher the noise level required to make the frequency audible.

The guidelines to assess infrasound are not as well established as the assessment of higher

frequency noise. In this report infrasound measurements were conducted in accordance with the

guidelines set out by the Queensland DEHP and the ISO standard 7196 (Roberts, 20046) (ISO:

7196:19954).

The general opinion on the assessment of infrasound is that it should be assessed in reference to

the hearing threshold for humans at these lower frequencies. The hearing threshold adopted in

2 Hessler, G.F., 2004 Proposed criteria in residential communities for low-frequency noise emissions from industrial sources, Journal of Noise Control Engineering 52(4), 2004 3 Broner, N. (2011). ‘A simple outdoor criterion for assessment of low frequency noise emission’, Acoustics Australia, Vol. 39, No. 1 pp. 7-14. 4 ISO: 7196:1995, “Acoustics Frequency-weighting characteristic for infrasound measurements”. 5 T. Watanabe and H. Møller, “Low Frequency Hearing Thresholds in Pressure Field and in Free Field,” Journal of Low Frequency Noise and Vibration, vol. 9, no. 3, 1990. 6 C. Roberts, “ECOACCES Guideline for the assessment of low frequency noise,” in ACOUSTICS 2004, Gold Coast, Australia, 2004.




this report is based on the research by W. Passchier –Vermeer and is also adopted in the Dutch

Guideline on low frequency noise and in the guidelines set out by DEHP (Passchier- Vermeer,

19987) (Geluidshinder, 19998) (Roberts, 20047). This threshold is similar but more conservative

than the international standard ISO 389 (ISO: 389-7: 20059). The ISO 389 standard is based on

the assumption that 50% of the people can hear noise below the threshold whereas the hearing

threshold adopted in this report assumes that only 10% of the people can hear below the hearing

threshold. Furthermore the ISO standard extends down to 20 Hz where the hearing threshold

adopted in this assessment goes down to 4 Hz, based on the measured thresholds. Because most

complaints about low frequency noise come from people aged between 50 and 60 years, it is

important to note that the threshold determined by Passchier-Vermeer is based on this age

group. The ISO norm is based on the age group between 18 and 25 years.

For frequencies below 20 Hz, the G-weighting is often used to assess the impact of noise in the

frequency range from 1 Hz to 20 Hz (ISO: 7196:19955). The G-weighting gives a high

weighting to frequencies between 1 and 20 Hz and a low weighting to frequencies outside this

range. A level of 85 dB (G) inside dwellings is often adopted as a criteria to protect the

environment for infrasound noise exposure as this is similar to the hearing threshold at these

frequencies (Roberts, 20047).

4.7 Backup Diesel Generator Criteria

The proposed use of the diesel generators is as follows:

To be operational initially during daytime only if required during network upgrades;

and

After construction of wind turbines and solar array, to be used to provide emergency

support to the grid while the 110kV power line is out of service, predicted to be less

than 4 events per year with an average duration of less than 6 hours.,

Given the proposed operation of the diesel generators will occasionally include night time use,

the internal sleep disturbance criteria provided by the World Health Organisation (WHO) for

constant noise sources, described as 30dBA LAeq10

is proposed. Assuming an inside/outside

adjustment of 7dBA, this equates to an external noise level criterion of 37dBA LAeq.

4.8 Construction Noise Criteria

Unless a local government has developed specific construction noise management policy, the

requirements contained in Section 440 of the Queensland Environmental Protection Act 1994

7 W. Passchier- Vermeer, “Beoordeling laagfrequent geluid in woningen,” TNO Preventie en Gezondheid (rapport 98.028), 1998. 8 N. S. Geluidshinder, “NSG-richtlijn laagfrequent geluid, Delft,” 1999. 9 ISO: 389-7: 2005, “Acoustics- Reference zero for the calibration of audiometric equipment - Part 7: Reference threshold of hearing under free-field and diffuse-field listening conditions, International Organization of Standardization, 2005”. 10 World Health Organization, “Guidelines for Community Noise”, Geneva, 1999.




apply. Construction noise levels are typically controlled by limiting the hours in which

construction activities are audible at the nearest residential dwellings, to the hours of 6.30 am

and 6.30 pm on business days and Saturdays. This approach does not place noise limits on the

construction activity during these hours. Outside of these hours the noise is to be “inaudible”.

Where circumstances do not allow the restriction of hours for construction activities, an

assessment of the potential noise emissions should be conducted along with the development of

a Construction Noise Management Plan (CNMP).




5.0 Baseline Noise Monitoring

5.1 Study Methodology

5.1.1 Site Selection

Baseline measurement site selection was carried out in consultation with Muirlawn project

personnel.

Properties for monitoring were selected to represent potentially affected residences near to the

proposed site of the wind farm, as shown on Figure 4 in Appendix A.

For a given property, the following criteria were used to select the physical location of the noise

logger:

separation from livestock to prevent accidental damage to instrumentation by the livestock;

separation from steady sources of noise that should not11 be regarded as normal features of the ambient noise environment. At a residential location this may include sources such as air-conditioners, pool pumps, septic pumps and radio noise (as examples);

separation from nearby vegetation to prevent vegetation noise contamination; and

preferences of the landowner for the monitoring site location, based on their knowledge of the property and their understanding of the monitoring location requirements.

Data relating to the baseline monitoring sites (shown in Figure 4) are summarised in Table 2.

Details of instrumentation, reference weather station location, and photographic records of

instrument locations are detailed in the appendices for each site.

11 As per advice in the Qld EPA Noise Measurement Manual




Table 2: Summary of Monitoring Sites

Measurement Location (Ref. Figure 4)

Description (based on description in Section 4.4)

GPS Coordinates (Latitude, Longitude)

Appendix Reference

Site N1 – Marini Rural living 28° 30'

48.4138'' S

151° 53'

16.4605'' E C.1

Site N2 – Savios Rural (apple plantation)

28° 30'

45.7956'' S

151° 52'

55.596'' E C.3

Site N3 – Paddock Adjacent to property which is rural living

28° 30'

35.6976'' S 151° 54' 16.3188'' E

C.4

5.1.2 Noise Monitoring Procedures

Noise monitoring was conducted in accordance with the following standards and procedures:

Australian Standard AS1055.1-1997 Acoustics – Description and measurement of environmental noise, Part 1: General procedures, and

Queensland DEHP12 Noise Measurement Manual (3rd Edition, 1 March 2000)

The monitoring duration was sufficient at each location to ensure that the minimum 2000 data

points was obtained, as required by the SA Guidelines.

5.1.3 Noise Monitoring Instrumentation

Baseline noise monitoring was conducted utilising CESVA SC310 Type 1 octave logging sound

analysers, CESVA C250 microphones with PA14 preamplifiers and CESVA TK1000 outdoor

microphone assemblies at 1.5m microphone height. The loggers have a low noise floor of

typically 16dBA or less. Also used on each microphone was a 150mm diameter secondary

windscreen GRAS AM0089 for use in high wind speed environments.

Noise levels were measured continuously throughout the monitoring period. The logger

recorded statistical parameters including LA10 and LA90 at 10 minute intervals with octave

frequency bands from 31.5Hz to 16kHz.

Baseline infrasound monitoring was conducted utilising the SINUS SK-1 monitoring system in

combination with a Microtech MK 222 (Microtech, Gefell, Germany) microphone with a

MV203 preamplifier. This combination of microphone, preamplifier and data acquisition system

has a good sensitivity over a large frequency range from 2.5 Hz to 10 kHz.

Instrumentation was field-calibrated prior to and following measurements.

5.1.4 Meteorological Monitoring Instrumentation

Simultaneous monitoring of wind speed, direction, temperature, pressure and humidity

conditions was conducted in the vicinity of baseline noise monitoring locations, in accordance

12 DEHP –Department of Environment and Heritage Protection. (Queensland Government)




with the requirements of AS1055.1-1997. The meteorological monitoring station sampled the

meteorological parameters at two second intervals. The weather data was post-processed to

produce summary information for 10 minute intervals corresponding to the noise monitoring

intervals. Sensors were located at a 3m reference height. The meteorological monitoring site is

indicated on Figure 4, in Appendix A. This weather station was used primarily to determine

which time periods were affected by rain.

Additional wind speed measurements were also carried out by the client on the site, with wind

anemometers at heights 40m, 50m and 60m above ground level. These measurements enabled

the wind speed at the hub height to be determined by extrapolation of the wind speed profile to

the hub height.

5.2 Analysis of Baseline Records

5.2.1 Seasonal Insect and Other Extraneous Noise

The DEHP Noise Measurement Manual indicates that the influence of insect noise on baseline

noise levels should be carefully considered. During warmer months sampling in rural locations

may include significant insect noise contribution to LA90 levels and may misrepresent baseline

conditions at other times of the year when insect noise may be less significant (Terlich 201113).

In rural Queensland during dry winter months, significant insect noise may be absent at night.

Octave spectral baseline logging has been conducted in the frequency range of 31.5Hz to 16kHz

to enable the identification of seasonal or episodic insect and frog noise. The presence (or

absence) of such noise was determined from inspection of the spectragram (or sonogram) for the

noise-monitoring period. The spectragram is a graphical plot of sound pressure level,

represented by colour, versus frequency (y-axis) and time (x-axis). Typically, when insect

activity is present, it may be identified as a constant contribution in one or more octave bands

above 2kHz, typically in the evening and night periods.

If significant evening or night-time insect noise is detected, the insect noise is filtered (i.e.

removed) by post-processing the measurement data prior to the correlation to the wind speed.

Baseline sampling was conducted in late autumn months between 15 March and 13 April 2013.

Some insect noise was evident on dusk at a number of monitoring sites but did not continue as a

persistent feature throughout the night-time. Some extraneous noise was observed at several

monitoring sites which included bird noise around sunset and sunrise. The extraneous noise

contribution was removed from the background noise data set.

5.2.2 Meteorological Conditions

Noise data that was affected by excessive wind speed or precipitation was excluded from the

aggregate noise level statistics. Intervals with any precipitation or average wind-speeds above

13 Terlich, M. 2011 ‘The Case for Spectral Measurements of Ambient Noise Levels in the Assessment of Wind Farms’ Proceedings of the Fourth International Meeting on Wind Turbine Noise, Rome, Italy 12-14 April.




7m/s were cross-referenced to the noise monitoring data and excluded from statistical summary

data.

For the purposes of standardising measurements and avoiding confusion regarding whether

wind is measured at hub height or another height, the SA Guidelines specify for measurements

relative to the WTG hub height. In this case, data has been standardised to wind speed at a hub

height of 80m agl which corresponds to the wind speeds provided in the WTG manufacturer

data.

5.2.3 Infrasound Analysis

From the collected background infrasound noise measurements the average background level

over a period of several days from March 28, 2012 was determined for each one-third octave

band from 2.5 Hz to 200 Hz. This was carried out separately for the day (7 am - 6 pm), evening

(6 pm - 10 pm) and night time periods (10 pm - 7 am).

The result is presented in Figure 15 in Appendix C where the average background level is

expressed in unweighted L90 dB, i.e. the noise level that is exceeded for 90 % of the time. The

human hearing threshold is presented in the same figure to provide a point of reference.

As can be observed in Figure 15, the average background level does not exceed the hearing

threshold for frequencies below 50 Hz. The average background levels measured start to exceed

the hearing threshold only at the 80 Hz one third octave band. The difference between the

average background levels in the day evening and night periods is less than 7 dB.

From the recorded data both the G-weighted L90 and the Leq were determined for each ten

minute recording during the measurement period. The results are presented in Figure 16, Figure

17, Figure 18 and Figure 19, for each day of recorded data. The recorded G-Weighted L90 and

Leq noise levels are much lower than the recommended noise limit of 85 dB (G) in dwellings

proposed by the Queensland DEHP Draft ECOACCESS Guideline- Assessment of Low

Frequency Noise (Roberts, 20047).

This confirms the ambient noise levels have an acceptable level of infrasound noise, particularly

as the infrasound would not be audible.

5.3 Wind Turbine Noise Criteria

Table 3 summarises the number of remaining data points at each monitoring location, following

the removal procedure described in Section 5.2.1 to remove insect noise and other extraneous

noise. It is noted that the SA Guidelines requires a minimum of 2000 useable data points with

background noise levels and wind speed measurements synchronised where at least 500 points

are collected in the worst-case wind direction. This data should be between the cut-in wind

speed and the speed of rated power. In this case, data between the speed of 3m/s and 14m/s at

hub height have been used.




Table 3: Number of data points at each monitoring location

Location Number of remaining data points

Marini 3766

Savios 2676

Site N3 – ref. House 1 3783

The measured background noise levels at the monitoring locations were correlated with the

wind speed data calculated from the wind data measured on the weather tower. A regression

analysis of the data was carried out to determine the line of best fit for the correlations in

accordance with the SA Guidelines. The data and regression curves are shown in Appendix C

for the three locations. Based on this analysis, the noise criteria determined in accordance with

the SA Guidelines at a range of wind speeds within the operating range of the turbines is shown

in Table 4. It should be noted that the base criterion of 40dBA was used at the Savios Receptor

as this location was noted to be a primary producer in the form of an apple plantation (ref.

footnote in Section 4.4).

Table 4: Determined Noise Criteria at Wind Speeds

Location Noise Criterion (dBA) at Wind Speed (ms-1)

7 8 9 10 11 12 13 14

Marini 36 38 40 43 46 49 52 56

Savios 40 40 41 43 45 47 49 51

House 1 36 38 40 42 44 46 49 52

It is assumed that the noise criteria at the receptor described as House 3, south of the Marini

receptor, would be identical to that at the Marini property. As House 3 is significantly further

from the site, if compliance with the noise criteria is achieved at the Marini receptor,

compliance would also be achieved at House 3.




6.0 Noise Modelling

6.1 Methodology

An environmental noise model of the site and surrounding area, including the noise sensitive

locations, was constructed using ISO 9613-2 (1996), Acoustics - Attenuation of Sound During

Propagation Outdoors, Part 2: General Method of Calculation, as implemented in SoundPLAN

software. The method predicts A-weighted sound pressure levels under meteorological

conditions favourable to propagation (mild temperature inversion with slight downwind) from

sources of known sound emission. The overall model accuracy is estimated to be ±3dBA.

The graphical noise contours generated by the model represent the envelope of results for noise

propagation in all directions (i.e. summary of typical worst-case noise propagation in all

directions relative to the noise source).

The calculation of sound propagation from the source to the receiver locations is calculated with

specific algorithms for the following physical effects:

geometrical divergence;

atmospheric absorption (in accordance with ISO 9613 Part 1);

ground effect;

reflection from surfaces;

screening by obstacles (horizontal and vertical diffraction); and

dense vegetation (none included).

The SoundPLAN software produces noise contours by interpolation from predicted grid noise

levels at 1.6m above local ground level. Point receptors were also utilised, at a height of 1.6m

above ground level at locations representative of the houses in the area.

The model terrain was based on elevation data sourced from Muirlawn Pty Ltd and was

modelled as 50% absorptive which is consistent with the predominant natural vegetation and

accepted modelling methodology both in Australia and internationally. Areas around the

generators and substations were modelled as packed earth, approximately 20% absorptive.

6.2 Source Sound Power Level Data

The Dalveen Wind Farm will consist of eight (8) General Electric Company 1.7-100 wind

turbine generators (WTG) with a hub height of 100m. Sound power data used to predict noise

impact of these turbines has been taken from a Test Report Technical Documentation - Wind

Turbine Generator Systems - 1.7-100 - 50 & 60 Hz prepared by GE Energy. The test was carried

out in accordance with International Standard IEC 61400-11, ed. 2.1: 2006.

The sound power spectra in octave bands at wind speeds from 7 m/s to the cut-out wind speed

of 14 m/s are shown in Table 8 in Appendix B. Each turbine was modelled as a point source at

the hub height of 100m agl at each of the specified wind speeds where the WTG is in operation.

Sound pressure level data for the proposed diesel generators including spectrum was provided

by the manufacturer. Sound power levels were calculated based on the provided dimensions of




the equipment. Sound power level data including spectrum for transformer noise was sourced

from data on file. The modelled sound power levels are shown in Table 9 in Appendix B.

6.3 Noise Model Scenarios

Each of the wind speeds for which data is available for the proposed eight WTG’s was modelled

as a separate scenario. The eight different speeds (7, 7.7, 8.4, 9.1, 11.1, 12.5 and 14 m/s)

encompass the wind speeds of operation, based on the wind at hub height.

An additional scenario was modelled including the proposed diesel generators. For this scenario,

six generators were modelled to represent the worst-case noise emissions during the initial day-

time maintenance activities on the electrical network. This scenario also represents the worst-

case noise emissions during any night-time power outages where the generators are required to

operate.

All scenarios included noise sources for the proposed substations on the site. Transformer noise

would be the most significant item in the substations.




7.0 Impact Assessment

7.1 Assessment of Proposed Wind Turbines

The predicted LAeq noise levels for the noise model scenarios for the eight different wind speeds

described in Section 6.3 are summarised in Table 5. The levels have been predicted at three

nearest noise sensitive receptors which are representative of the study area. The noise contours

for the worst-case wind speed with regard to both the sound power level and the relevant criteria

are shown in Figure 6, Figure 7 and Figure 8 for the 9.1ms-1, 9.7ms-1 and 11.1ms-1 wind speed

scenarios respectively.

Table 5: Predicted Noise Levels LAeq at Receptor Locations – 8 WTG at 100m hub height

Residential Receptor

Predicted Noise Levels LAeq (dBA) at Wind Speed (ms-1)

7.0 7.7 8.4 9.1 9.7 11.1 12.5 14.0

House 1 32.7 35 37.2 39.2 40.6 41.5 41.6 41.6

Marini 32.3 34.3 36.4 38.2 39.6 40.4 40.5 40.5

Savios 28.9 31.3 33.4 35.4 36.8 37.7 37.8 37.8

The predicted noise levels from the wind turbines have been assessed against the relevant

criteria according to the SA Guidelines. The graphical comparison of the predicted noise levels

at each receptor with the determined noise criteria are shown in Figure 1 to Figure 3.

Figure 1: Predicted Noise Levels at House 1 Receptor for increasing wind speed




Figure 2: Predicted Noise Levels at Marini Receptor for increasing wind speed

Figure 3: Predicted Noise Levels at Savios Receptor for increasing wind speed




Based on the predicted noise levels summarised in Table 5 and shown graphically in Figures 1

to 3, the GE-1.7 turbines are predicted to comply with the relevant noise criteria at all residences

for all wind speeds.

7.1.1 Assessment of Low Frequency Noise from Wind Farm

The noise emissions from the wind farm were modelled using the ISO Method implemented in

SoundPLAN software to predict the external Z-weighted (dB) and C-weighted (dBC) noise

levels at the identified receptors, as well as the difference between the A-weighted (dBA) and

C-weighted (dBC) noise levels.

The C-weighting includes nearly all of the low frequency energy of a noise event, while the Z-

weighting includes all of the low frequency energy of a noise event. This is contrast to the A-

weighting which approximates the frequency response of the human hearing, which is less

sensitive to low frequency noise (refer to Appendix D for weighting descriptions).

Table 6 provides a summary of the predicted LCeq at the identified receptors and the difference

between C-weighted and A-weighted noise levels, along with the most significant contributors

to the C-weighted noise levels. The Z-weighted noise levels have also been included for

completeness.

Table 6: Assessment of potential external low frequency noise

Residential Receptor (ref. Figure 4)

Predicted Overall Noise Levels, Difference

(LCeq-LAeq) Potential LFN problem?

Primary sources of dBC levels LAeq,

1hr LCeq,

1hr LZeq,

1hr

House 1 41.6 58.4 60.4 17 No Wind Turbines

Marini 40.5 58.3 60.3 18 No Wind Turbines

Savios 37.8 54.5 56.7 17 No Wind Turbines

Based on the external assessment conducted, it is unlikely that there will be a low frequency

noise problem from the proposed wind farm.

7.1.2 Assessment of Infrasound from Wind Farm

The current ambient noise environment does not contain significant audible levels of infrasonic

noise.

A survey in 2005 of all known published measurements of infrasound from wind turbines at the

time, stated “The survey indicates that wind turbines of contemporary design with an upwind




rotor generate very faint infrasound with a level far below the threshold of perception even at a

rather short distance” (Jakobsen, 200514).

At a distance of 100 metres from the wind turbines Jakobsen observed that the dB(G) level

remained below 80 dB(G). Therefore the infrasound levels resulting from the proposed wind

farm is not expected to exceed the infrasound criteria of 85 dB(G) inside the dwellings near the

proposed site.

This assumption should be confirmed with infrasound measurements once the proposed wind

farm is operational.

7.1.3 Assessment of Substation noise

Noise from the substations was included in the noise predictions for the turbines in Section 7.1.

At the worst-case receptor (closest to the proposed substations) the component noise level from

the substations is calculated to be 25dBA. This noise level is 10dBA below the base level of the

SA Guidelines and as such is not anticipated to adversely impact on the amenity of the

residences surrounding the proposed wind farm.

7.2 Assessment of Backup Diesel Generators

The predicted LAeq noise levels for the backup diesel generator noise model scenarios described

in Section 6.3 are summarised in Table 7. The levels have been predicted at three nearest noise

sensitive receptors which are considered representative of the study area.

Table 7: Predicted Noise Levels LAeq– 6 Backup Diesel Generators

Residential Receptor

Predicted Noise Levels LAeq, adj

(dBA) House 1 55

Marini 61

Savios 51

To achieve the 37dBA LAeq at the nearby receptor locations will require the application of

attenuation measures to the diesel generators to achieve a noise reduction of at least 24dBA.

Attenuation measures to achieve this level of noise reduction should be investigated and may

include:

modification of the location of the diesel generators to minimise noise emissions to

receptors due to increased distance or shielding from terrain. Note that this measure

would not achieve the noise criteria in isolation (ie. construction of enclosures described

below would also be require, though overall attenuation requirements may reduce if

equipment is relocated);

14 Jakobsen, J. 205 ‘Infrasound Emission from Wind Turbines’,Journal of low frequency noise, vibration and active control, , vol. 24, no. 3, 2005.




use of quieter equipment, to reduce the level of attenuation required by an acoustic

enclosure, though of a lesser performance;

construction of either enclosure around individual generators or enclosure around all

generator units, which would include internal absorption inside the enclosure (walls and

roof), and attenuated intake and exhaust ventilation paths. Enclosures of proprietary

design could be supplied by the generator manufacturer, or alternatively an acoustically

treated plantroom building could be designed, or a specialist noise enclosure

manufacturer could be engaged to manufacture enclosures to achieve specific

attenuation requirements. These treatments should be designed after the location and

type of equipment is finalised.

7.3 On-site and Off-site Construction Assessment

For construction of the wind farm, solar array, backup diesel generators and associated

infrastructure, it is recommended that, where possible, construction activities that may result in

noise being audible at the nearest residential dwellings be conducted between the hours of 6.30

am and 6.30 pm on business days and Saturdays.

A Construction Noise Management Plan (CNMP) will be prepared and implemented for

construction activities so that potential noise impacts during construction and commissioning,

(particularly if required outside of standard daytime working hours), are minimised at noise

sensitive receptors.

The CNMP should include at least the following requirements:

for construction of the wind farm, solar array, backup diesel generators and associated

infrastructure: normal hours for noise emitting construction activities limited to the

period 0630 – 1830 on business days and Saturdays;

the Construction Manager will ensure construction is undertaken in accordance with an

Environmental Management Plan which will include a Noise Control Plan for any

significant out-of-hours works;

the Construction Manager will be responsible for establishing processes with relevant

contractors to ensure that regular “tool-box” meetings with workers are held throughout

the construction period, where best practice methods to minimise noise impact of

construction activities will be reviewed and discussed with the workers;

the noise control plan should be in general accordance with AS 243615 regarding

selection of equipment and processes to be used on site, maintenance of equipment, use

of temporary screens and enclosures as appropriate;

15 AS 2436 - 1981: Guide to Noise Control on Construction, Maintenance and Demolition Sites




an effective community consultation program with occupants of the nearest noise

sensitive buildings will be implemented and maintained throughout the construction

period;

a Complaints Register will be established and maintained throughout the construction

period. Upon receipt of a complaint, a process to investigate the complaint and

undertake suitable remedial action or monitoring shall be initiated with the complaints

and results of investigations recorded.




8.0 Recommendations

Wind Turbines

The wind turbine generators should be selected to produce sound power levels not greater than

those provided for the proposed WTG in Appendix B. The location of the WTG should be as

shown in Appendix A.

Diesel Generators

To achieve the 37dBA LAeq at the nearby receptor locations will require the application of

attenuation measures to the diesel generators to achieve a noise reduction of at least 24dBA.

Attenuation measures to achieve this level of noise reduction should be investigated and may

include:

modification of the location of the diesel generators to minimise noise emissions to

receptors due to increased distance or shielding from terrain. Note that this measure

would not achieve the noise criteria in isolation (ie. construction of enclosures described

below would also be require, though overall attenuation requirements may reduce if

equipment is relocated);

use of quieter equipment, to reduce the level of attenuation required by an acoustic

enclosure, though of a lesser performance;

construction of either enclosure around individual generators or enclosure around all

generator units, which would include internal absorption inside the enclosure (walls and

roof), and attenuated intake and exhaust ventilation paths. Enclosures of proprietary

design could be supplied by the generator manufacturer, or alternatively an acoustically

treated plantroom building could be designed, or a specialist noise enclosure

manufacturer could be engaged to manufacture enclosures to achieve specific

attenuation requirements. These treatments should be designed after the location and

type of equipment is finalised.

Construction Noise

For construction of the wind farm, solar array, backup diesel generators and associated

infrastructure, it is recommended that, where possible, construction activities that may result in

noise being audible at the nearest residential dwellings be conducted between the hours of 6.30

am and 6.30 pm on weekdays and Saturdays.

It is recommended that a Construction Noise Management Plan be prepared and implemented

for all construction activities so that potential noise impacts during construction (including

commissioning) are minimised at noise sensitive locations.

Noise Monitoring once Operational

Commissioning measurements are recommended to ensure that target noise levels are achieved

for the wind farm site. If access is available, internal infrasound noise measurements should be

repeated to confirm that infrasound noise levels continue to be below the hearing threshold.




9.0 Conclusions

From the assessment of Dalveen wind farm noise impacts the following conclusions can be

drawn:

Wind Turbines

The proposed 8 wind turbines will comply with the derived noise criteria. As mentioned in

Section 3.0, it should be noted that Figure 5 includes an additional turbine (T8) to the eight

assessed, which is excluded from this assessment. Turbine (T8) would not meet the criteria at

House 1, but could be considered if arrangements were made for the removal of this sensitive

receptor.

Diesel Generators

The derived 37dBA LAeq criterion at the nearby receptor locations can be achieved with the

investigation of suitable noise control measures such as the recommended noise attenuation

measures. These include: relocation of the generators, use of quieter units and acoustic

enclosure of the units.

Construction Noise

Using the Construction Noise Management Plan, potential noise impacts during construction

(including commissioning) will be minimised at noise sensitive locations.




Appendix A - Figures

Figure 4: Monitoring Locations and Site Location

Wind Farm Site

Savios Receptor

Marini Receptor House 1 Receptor Meteorology

station




Figure 5: Proposed Site Layout




Figure 6: Noise Emissions for 8 operating WTG 9.1m/s – GNM 1.6m agl




Appendix B - Modelled Sound Power Levels

Table 8 : Sound Power Level Spectra of equipment of WTG - GE 1.7-100

Hub height wind speed at 80 m

[m/s]

Source Height agl (m)

Linear sound power level (dB) in octave centre frequency (Hz) Total apparent

sound power level LWA.k (dBA)

Linear SWL (dB) 31.5 63 125 250 500 1k 2k 4k 8k 16k

7 100 112 108.1 103 99.4 96.2 91.7 89.2 82.3 64 24.9 98.2 114.1

7.7 100 114 110.2 105.2 101.8 98.8 94 91.2 84.9 67.1 27.5 100.6 116.2

8.4 100 115.9 112.1 107.2 104 101.2 96.2 93.1 87 70 30.2 102.8 118.1

9.1 100 117.7 114.1 109 105.4 103.1 98.6 94.7 88.8 72 32.2 104.7 120.0

9.7 100 119.3 115.9 110.6 106 104.1 100.8 96.5 89.4 71.4 34.1 106.1 121.6

11.1 100 120.8 117.2 111.9 106.1 103.7 102.6 98 89.2 72.7 34.6 107 122.9

12.5 100 121 117.3 112 106.1 103.6 102.8 98.1 88.5 71 34.3 107 123.1

14 100 120.9 117.2 111.9 106.1 103.6 102.8 97.8 87.9 70.3 35.2 107 123.0




Table 9 : Sound Power Level Spectra of equipment – Transformer and Backup Generators

Equipment Item Source Height agl (m)

Linear sound power level (dB) in octave centre frequency (Hz)

Overall sound

power level (dBA)

Linear SWL (dB)

63 125 250 500 1k 2k 4k 8k

Transformer 2 87 92 93 88 74 65 58 52 88 97

3512BDITA Caterpillar Diesel Engine -

Mechanical Noise 2 117 124 133 124 119 118 115 119 128 135

3512BDITA Caterpillar Diesel Engine -

Exhaust Noise (unsilenced) 3 119 130 125 118 116 118 118 115 125 132




Appendix C - Background Noise Level Summary

C.1 Marini House – External

Site No: Marini House (15/03/2013 02:00:00 PM)

Calibrator: Bruel & Kjaer 4231 Serial No: S/N 2463922

Logging Period: Friday, 15 March 2013 to Thursday, 28 March 2013

Instrument: CESVA SC-310 Serial No: S/N T229728 (Logger 7)

Logging Period: Thursday, 28 March 2013 to Saturday, 13 April 2013


Reference Weather Station: Reinhardt MWS 9-5, S/N 1020375

Comments:

The logger was located near the corner of the carport attached to the house.

Insect noise evident in the data in the 4kHz band, especially during the evening and night periods.




Figure 9: Pictures of Noise Logger Location at Marini House

Noise Logger

Marini House




Figure 10: Pictures of Noise Logger and Weather Station (WS3) Locations at Marini House

Weather station

Noise Logging Location

Weather station




Figure 11: Aerial Photo showing Noise Logger and Weather Station (WS3) Locations at Marini House




Figure 12: Marini House – Correlation of Background Noise Level and rated wind speed at reference height of 80m agl




C.2 Marini House – Internal Infrasound Measurements

Site No: Marini House (28/03/201312:50:00 PM)


Logging Period: Friday, 28 March 2013 to Sunday, 31 March 2013

Instrument: SINUS SK-1 Serial No: ST-R-019




Figure 13: Pictures of Infrasound microphone Location inside Marini House Living Room




Figure 14: Picture of Infrasound Logging Location inside Marini House Living Room




Figure 15: Average unweighted L90 levels for day, evening and night time periods per one-third octave band.




Figure 16: Weighted measured noise levels Leq, L90 on the 28th of March.




C.3 Savios House

Site No: Savios House (15/03/2013 03:00:00 PM)




Logging Period: Thursday, 28 March 2013 to Friday, 5 April 2013



Comments:

The logger was located near the corner of the house, adjacent to apple orchards covered by netting.





Figure 20: Pictures from Noise Logger Location at Savios House




Figure 21: Aerial Photo showing Noise Logger Location at Savios House




Figure 22: Savios House – Correlation of Background Noise Level and rated wind speed at reference height of 80m agl




C.4 Site 3

Site No: Site 3 (15/03/2013 01:00:00 PM)




Logging Period: Thursday, 28 March 2013 to Friday, 5 April 2013



Comments:

The logger was located in the paddock west of the residential house.

Logger was installed in a fenced enclosure in a paddock which occasionally had cattle grazing nearby.





Figure 23: Pictures from Noise Logger Location at Site 3 (west of House 1)




Figure 24: Aerial Photo showing Noise Logger Location at Site 3




Figure 25: Site 3 – Correlation of Background Noise Level and rated wind speed at reference height of 80m agl




Appendix D - Acoustic Terminology and Units of Measurement

D.1 Abbreviations

Abbreviation Meaning oC degrees Celsius agl Above ground level AHD Australian Height Datum AS Australian Standard AS/NZS Australian Standard / New Zealand Standard BCA Building Code of Australia BoM Bureau of Meteorology dBA A measured sound pressure level that incorporates A-weighting is denoted

LpA, and has units of dB(A), often written as dBA dBC A measured sound pressure level. The ‘C’ frequency weighting adjustments

are much reduced at low frequencies compared to ‘A’ weighting, giving greater ‘prominence’ to the low-frequency components in the overall measured dBC sound pressure level compared to the measured dBA sound pressure level

dBG A measured sound pressure level. The ‘G’ frequency weighting adjustments are specific to infrasound measurements, with weighting adjustments which highlight the frequencies below 20Hz.

dBZ A measured sound pressure level, which replaces the previous description of Linear or Flat. The ‘Z’ frequency weighting consists of no adjustments to the measured level.

EP Act Environmental Protection Act 1994 EPP Environmental Protection Policy EPP (Noise) Environmental Protection (Noise) Policy 2008 g grams Hz Hertz kg kilograms km kilometre km/h kilometre per hour LAeq(24hour), Time averaged A-weighted equivalent continuous sound pressure level over a

time period of 24 hours LAmax Average maximum A-weighted sound pressure level LAeq Time averaged A-weighted equivalent continuous sound pressure level LA90 A-weighted sound pressure level which is exceeded for 90% of the

measurement period. Often referred to as the Background noise level. LA10 A-weighted sound pressure level which is exceeded for 10% of the

measurement period. LA01 A-weighted sound pressure level which is exceeded for 1% of the

measurement period. m metre m/s metres per second




Abbreviation Meaning maxLpA maximum instantaneous noise level with time weighting set to Fast response m2 square metres m3 cubic metres PNL planning noise level PPV peak particle velocity Qld Queensland t tonnes VPD vehicles per day

D.2 Glossary of Terms

Abbreviation Meaning Ambient noise level

Concept of the all-encompassing noise level environment at a location of interest. A full description of the ambient noise level includes description of level variations in time and variations in the frequency composition in time, including subjective audible characteristics.

Auditory frequency range

A frequency range in which sounds are potentially perceivable by humans, often reported as 20Hertz – 20kiloHertz (1 Hertz = 1 cycle per second).

Background noise level (LAbg)

Concept of the typical minimum ambient noise level, numerically evaluated from the level exceeded for 90 percent of 15 minute sample periods (LA90,15 minute) during a defined time period of interest (e.g. daytime, evening or night-time).

Baseline noise level

Concept of the noise level prior to a development, that can be evaluated by a range of level parameters such as the minimum (LAmin), average (LAeq), maximum (LAmax) and percentile descriptors (LA1, LA10, LA90).

Broadband noise A noise with approximately equal acoustic energy distribution over a large range of frequencies, for example 100Hz – 2KHz. Natural examples include noise from a waterfall, or the sound of wind in trees.

Construction/blast vibration

Transient oscillating movement of the ground or a building structure from transmission of elastic pressure waves from the vibration source, through the ground to the receptor location.

Environmental Management Plan

A document developed by proponents during a project’s planning and design. An Environmental management plan (EMP) provides life-of-project control strategies in accordance with agreed performance criteria for specified acceptable levels of environmental harm. It may continue through the whole life of a project (e.g. preconstruction, construction, operation and decommissioning).

Octave spectrum The frequency content of a noise is described by a frequency spectrum. A frequency spectrum can be expressed as a octave spectrum, which, instead of displaying every frequency individually, is comprised of sub-frequency ranges centred at the following frequencies, measured in Hertz (1 Hertz = 1 cycle per second): 31.5, 63, 125, 250, 500, 1000, 2000, etc.

One-third-octave spectrum

The frequency content of a noise is described by a frequency spectrum. A frequency spectrum can be expressed as a one-third-octave spectrum, which, instead of displaying every frequency individually, is comprised of sub-frequency ranges centred at the following frequencies, measured in Hertz (1 Hertz = 1 cycle




Abbreviation Meaning per second): 20, 25, 31.5, 40, 50, 63, 80, 100, 125, 160, 200,250, 315, 400, 500, 630, 800, 1000, 1250, etc.

Planning noise level

Nomenclature specific to the Department of Environment and Resource Management Ecoaccess guideline ‘Planning for noise control’ defining the permissible noise contribution from a proposed facility at a defined receptor.

Rating background noise level

Nomenclature specific to the Department of Environment and Resource Management Ecoaccess guideline ‘Planning for noise control’ defining the background noise level from LA90,15miute levels during the day, evening and night over a minimum seven day period.

Receptors a) Sensitive component of the ecosystem that reacts to, or is influenced by environmental stressors (as defined in the Aquatic Ecology chapters). b) Sites from which the proposed Project can be seen (as defined in the Landscape and Visual Amenity chapters). c) A place that may be sensitive to additional noise associated with a proposed development (as defined in the Noise and Vibration chapters).

Sampling sites Specific locations within the study area where data is collected. Stakeholder A person or organisation with an interest or stake in a project. Temporary accommodation facility

Onsite accommodation for the construction and/or operational workforce.

Terms of Reference

As defined by Part 4 of the State Development and Public Works Organisation Act 1971.

Tonality Noise containing a prominent frequency and characterized by a definite pitch Topography A description of the surface features of a place or region.

D.3 Human Response to Sound

Sound consists of small air-pressure fluctuations or pressure waves. The human auditory system

responds to both the intensity (or pressure-wave amplitude) of a sound, and the frequency

(number of pressure cycles per second), of a sound. These pressure fluctuations travel along the

ear canal and vibrate the ear-drum. The vibrations of the ear-drum are transmitted via the

middle-ear to the inner ear, where the frequency and amplitude are coded into electrical signals

for interpretation by the brain so that one can sense sound ‘pitch’ and ‘loudness’.

D.4 Sensitivity to Sound Level

Laboratory testing of the hearing of a large number of human subjects has been conducted by

scientists to determine the ‘threshold’ of human hearing. This threshold is the ‘quietest’ sound

that can be just determined by the human ear under ideal (quiet) laboratory conditions. This

nominal hearing threshold has been quantified as a Root Mean Squared (RMS), or ‘average’

pressure fluctuation of 0.00002 Pascals (or 20 Pa).

The upper limit of human hearing for sounds of short duration (above which the auditory system

is rapidly unable to translate information about level and frequency) is an RMS pressure

fluctuation of around 20 Pascals (20 Pa).




To provide a more manageable scale for the wide numerical range of sound pressures that the

human ear is able to respond (i.e. 0.00002 Pa to 20 Pa), it is conventional to define a Sound

Pressure Level as the ratio of a given sound pressure (p) relative to the human threshold of

hearing (pref = 20 Pa RMS) as follows:-

Sound Pressure Level, Lp = 10*log10(p2/pref

2)

With this definition, the nominal threshold of hearing becomes zero decibels (or 0 dB), and the

maximum ‘clearly’ audible level becomes 120 dB, referenced to 20 Pa.

So, 0 dB is about the quietest level of introduced sound that a person with healthy hearing could

detect in a much quieter laboratory. A level of 120 dB is what might be experienced close to

loudspeakers at a loud rock concert, or close to an industrial nailing gun. Two people

conversing might speak at levels that are about 50 dB to 60 dB when separated by a distance of

one metre.

From laboratory studies of subjects it is found that a 10 dB increase in a sound is approximately

perceived as a subjective doubling in loudness. Conversely a 10 dB decrease in a sound is

perceived as a halving in loudness.

D.5 Sensitivity to Sound Frequency

At any instant the acoustic environment contains a ‘smorgas-board’ of sound components at

different frequencies and at different levels. A person speaking, as an example, will

simultaneously produce vowel sounds typically in the range of 250 Hertz to 1 kHz, and higher

frequency sounds associated with consonants, such as ‘hisses’ and ‘clicks’ in the range of 2 kHz

to 8 kHz.

Human hearing has the greatest sensitivity to sound at frequencies in the range of 2 kHz to 4

kHz, with decreasing sensitivity at higher and lower frequencies. At 1 kHz the sensitivity is only

slightly lower ( -1dB, or around 90% of optimal pressure sensitivity), whereas at 100 Hz the

sensitivity is much lower (- 19 dB, or around 10% of optimal pressure sensitivity).

D.6 Sound Level Meters and A-weighting

The Sound Level Meter was invented to enable systematic investigation and study of sound that

is of concern to humans. One of the tasks of the sound level meter is gauge the level of a sound,

as it may be perceived by the human ear. This is not easy as the human ear not only has

different sensitivities depending on the frequency of sound, but the sensitivity also changes as

the level of the sound changes. The ‘A-weighting’ system is an internationally agreed system of

sensitivity adjustments to measured sound at frequencies ranging from 10 Hz to 20 kHz, to

enable a sound level meter to approximate the sound level response of the human auditory

system. So a sound pressure level with an ‘A frequency weighting’ or ‘A-weighting’ means we

are trying to gauge the significance of a measured sound pressure level to the human ear.

A measured sound pressure level that incorporates ‘A-weighting’ is denoted LpA, and has units

of ‘dB(A)’, often written ‘dBA’.




D.7 Tonality and Impulsivity Adjustments to Measured Levels

‘A-weighting’ is a somewhat crude approximation to hearing sensitivity, as the human ear is

also expert at ‘tuning-in’ to tones, sound patterns and rhythms. A person is able, for example, to

identify a siren at a distance before it will register on a simple sound level meter. Similarly,

hearing is attuned to sounds that change rapidly in level, such as bangs, and knocks which are

described as ‘impulsive’. To account for these discrepancies between human sensitivity and

sound level meter sensitivity a tonal adjustment or an impulse adjustment to the measured

level is defined16. A measured sound pressure level that has been adjusted to account for the

increased audibility by virtue of its impulsive or tonal characteristics is denoted LA,adj.

D.8 Response Time

The human auditory system has a certain ‘delay’ in responding to noise. For extremely ‘fast’

sources of noise, such as a gun-shot at the ear of the firer, the increase in sound is so rapid that

the hearing system is unable to respond quickly enough for the protective muscular reflex of the

ear-drum to operate.

Sound level meters are designed to emulate the ‘response-speed’ of the human auditory system.

This is conventionally described as the ‘Fast response’ sound level meter response setting 17.

D.9 Descriptors for Environmental Noise Assessment

Common noise sources, such as industrial processes, transportation (cars, trucks, trains), natural

noise (wind in trees, birds, insects) vary with time. So during a measurement period of duration

‘T’ (e.g. a 10 minute measurement) there is a need to define whether the maximum, minimum,

average, or a percentile statistical level within that time interval is being specified.

In a quiet rural area as an example, the maximum sound pressure level for a fraction of a second

from a nearby bird call may be 80 dBA, whereas the minimum sound pressure level between

bird calls, and when the trees are still, may be 20 dBA. Without statistical definition, the level

range of 20 dBA to 80 dBA would be confusing.

The following level parameters are therefore used to describe the ‘prevalence’ of a sound at

different sound pressure levels with time (all ‘Fast response’, ‘A-weighted’, RMS sound

pressures levels relative to a 20 Pa reference pressure):-

LAmax,T the maximum level in time interval ‘T’

LAmin,T the minimum level in time interval ‘T’

16 The methodology for this adjustment is described in AS1055.1 Acoustics-Description and measurement of environmental noise Part 1: General Procedures 17 Objective measures of gun-shot noise or other explosive events, in the context of hearing damage potential, use a Peak sound pressure level detection to ensure that the actual maximum sound pressure impacting on the human subject is known.




LAeq,T the theoretical constant level with the same sound energy as the actual fluctuating level in a time interval ‘T’

LA1,T the level exceeded for 1 percent of time interval ‘T’

LA10,T the level exceeded for 10 percent of time interval ‘T’

LA90,T the level exceeded for 90 percent of time interval ‘T’, often termed the ‘background’ level.

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