nsw industrial noise policy · 2004-04-16 · control of the noise impacts by the appropriate...

NSw Industrial Noise Policy

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NSW IndustrialNoise Policy

NSW Industrial Noise Policy

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Published by:

Environment Protection Authority59–61 Goulburn StreetPO Box A290Sydney South 1232Phone: (02) 9995 5000 (switchboard)Phone: 131 555 (information & publications requests)Fax: (02) 9995 5999

E-mail: [email protected]: www.epa.nsw.gov.au

The EPA is pleased to allow this material to be repro-duced in whole or in part, provided the meaning isunchanged and its source, publisher and authorshipare acknowledged.

ISBN 0 7313 2715 2EPA 00/1

For technical information about this report, please contact:

Noise Policy SectionEnvironmental Policy BranchEnvironment Protection AuthorityPhone: (02) 9995 5000

Cover photo: Australian Picture Library/CorbisJanuary 2000Printed on recycled paper

NSw Industrial Noise Policy

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Contents

1 Policy framework ............................................................................................................................................ 1

2 Industrial noise criteria ................................................................................................................................ 14

3 Determining existing noise levels ............................................................................................................... 22

4 ‘Modifying factor’ adjustments .................................................................................................................. 28

5 Meteorological conditions ........................................................................................................................... 31

6 Predicting noise levels & determining impacts ......................................................................................... 36

7 Mitigating noise from industrial sources ................................................................................................... 38

8 Negotiation process ...................................................................................................................................... 43

9 Consent/licence conditions ........................................................................................................................ 47

10 Applying the policy to existing industrial premises ................................................................................ 49

11 Reviewing performance .............................................................................................................................. 51

12 Policy evaluation and review ..................................................................................................................... 54

References ............................................................................................................................................................ 55

Definitions of terms ............................................................................................................................................. 56

Appendix A—Worked case studies .................................................................................................................. 60

Appendix B—Applying the background noise policy ................................................................................... 68

Appendix C—Procedure for assessing noise increase due to temperature inversions .............................. 73

Appendix D—Estimating noise increase due to inversions .......................................................................... 77

Appendix E—Methods for determining the frequency of temperature inversions ..................................... 78

Appendix F—Percentage occurrence of F-class temperature inversions in winter in the Hunter Valley, NSW ................................................................................................................................ 85

NSW industrial noise policy

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1 Policy framework

1.1 Overview of the policy

The adverse effects of noise on communities are wellreported in the literature (for review see Berglund &Lindvall, eds, 1995). These vary from direct effects(including noise-induced hearing loss, speechinterference, sleep disturbance and annoyance), toindirect or secondary effects, such as long-termeffects on physical and mental health as a result oflong-term annoyance and prolonged disturbance tosleep. The World Health Organization defineshealth as a state of complete physical, mental, andsocial well-being, not just as the absence of disease(WHO 1947). Community reaction to noise has beennoted as a likely indirect cause of adverse healtheffects (Job 1996).

The overall aim is to allow the need for industrialactivity to be balanced with the desire for quiet inthe community.

The broad operating objectives involve requirementsto protect, restore and enhance the quality of theenvironment in New South Wales. In so doing, theEPA must have regard to the need to maintainecologically sustainable development, reduce therisks to human health and prevent the degradationof the environment. This policy seeks to promoteenvironmental well-being through preventing andminimising noise. It provides the framework andprocess for deriving noise limit conditions forconsents and licences that will enable the EPA toregulate premises that are scheduled under theProtection of the Environment Operations Act 1997.

The specific policy objectives are:

• to establish noise criteria that would protectthe community from excessive intrusive noiseand preserve amenity for specific land uses—these are set out in Section 2

• to use the criteria as the basis for derivingproject specific noise levels

• to promote uniform methods to estimate andmeasure noise impacts, including aprocedure for evaluating meteorologicaleffects—these are set out in Sections 3 to 6

• to outline a range of mitigation measures thatcould be used to minimise noise impacts—these are set out in Section 7

• to provide a formal process to guide thedetermination of feasible and reasonablenoise limits for consents or licences thatreconcile noise impacts with the economic,social and environmental considerations ofindustrial development—this is covered inSection 8

• to carry out functions relating to theprevention, minimisation and control ofnoise from premises scheduled under the Act.

1.2 Who is the policy for?

The policy is technical in orientation and is directedtowards industry, acoustic practitioners and con-sent authorities that require a degree of technicaldetail to assess impacts properly and developmitigation methods.

Responsibility for applying the policy lies with:

• the land-use planner (such as a local counciland the Department of Urban Affairs andPlanning—DUAP), through taking accountof likely impacts at an early stage in theplanning process so that incompatibledevelopments are appropriately located; also,in recognising the importance of maintainingseparation distances between industry andresidents. In locating potentially noisydevelopments, it is essential to recognise thatmitigation of the effects of noisy activitiesonce these are established will be limited bycost and design factors.

• the land-use managers and regulators (suchas local government, DUAP and the EPA),who act as determining authorities and asregulators of land-use activities. Their role isin providing adequate regulation of noise topreserve amenity and in ensuringcompliance with noise conditions.


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• the noise-source proponent and manager,through consideration of noise issues at theplanning stage of a project and through directcontrol of the noise impacts by theappropriate combination of noisemanagement tools and engineering design ofthe source.

1.3 Scope of the policy

The policy is specifically aimed at assessing noisefrom industrial noise sources scheduled under thenew Protection of the Environment Operations Act1997. It will be used as a guide by EnvironmentProtection Authority (EPA) officers for settingstatutory limits in licences for these sources. Localgovernment is an independent regulator for noiseunder the legislation, and thus has discretion indealing with noise within its area of responsibility.The policy is designed for large and complexindustrial sources and specifies substantial moni-toring and assessment procedures that may notalways be applicable to the types of sources coun-cils need to address. However, local governmentmay find the policy helpful in the carrying-out of itsland-use planning responsibilities (for example, thesetting of targets in local and regional environmen-tal plans).

In general, the types of noise sources dealt with inthe policy are:

• facilities (encompassing all the activitiestaking place within the property boundary ofthe facility) usually comprising many sourcesof sound, including

—industrial premises

—extractive industries

—commercial premises

—warehousing facilities

• maintenance and repair facilities

• individual industrial sources, such as

—heating, ventilating and air conditioning(HVAC) equipment

—rotating machinery

—impacting mechanical sources

—other mechanical equipment and machin-ery such as conveyors

—mobile sources confined to a particularlocation, such as draglines and haultrucks.

The policy’s focus is on the noise emitted fromindustrial sites and how this may affect the amenityof nearby receivers. Internal or occupational noisewithin any workplace is a separate issue adminis-tered by the WorkCover Authority under the Occupa-tional Health and Safety Act 1983.

Examples of noise sources that are NOT dealt withby the policy are:

• transportation corridors (roadways, railwaysand air corridors)

• motor sport facilities

• construction activities

• noise sources covered by regulations(domestic/neighbourhood noise).

Noise from vehicle movements associated with anindustrial source is covered by the industrial noisesource policy if the vehicles are not on a publicroad. If the vehicles are on a public road, the Envi-ronmental Criteria for Road Traffic Noise (EPA 1999)apply.

In particular instances specific noise criteria may bedefined for sources where the standard approach isnot appropriate, for example, wind farms.

1.4 Applying the policy

The assessment of noise impact is complex andsubjective, and is rarely (if ever) able to be consid-ered in isolation from other social and economicaspects of a development or activity. The policyoutlines processes to help strike a feasible andreasonable balance between the establishment andoperation of industrial activities and the protectionof the community from noise levels that are intru-sive or unpleasant.

In summary, noise management involves the follow-ing main steps:

1. Determining the project specific noise levelsfor intrusiveness and amenity that arerelevant to the site or the area (Section 2).


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2. Measuring and determining existing back-ground and ambient noise levels, using themethod relevant to the expected level ofimpact (as outlined in Section 3).

3. Where the proposed development is expectedto produce annoying noise characteristics,adjustments are to be applied to the noiselevels produced by the development inquestion (as outlined in Section 4).

4. Predicting or measuring the noise levelsproduced by the development in question,having regard to meteorological effects (suchas wind, temperature inversions) (see Section5).

5. Comparing the predicted or measured noiselevel with the project-specific noise levels andassessing impacts (Section 6).

6. Considering feasible and reasonable noisemitigation strategies where the project-specific noise levels are exceeded (Section 7).

7. Negotiation between the regulatory/consentauthority and the proponent and between thecommunity and the proponent to evaluate theeconomic, social and environmental costsand benefits from the proposed developmentagainst the noise impacts (Section 8).

8. The regulatory/consent authority setsstatutory compliance levels that reflect theachievable and agreed noise limits for thedevelopment (Section 9).

9. Monitoring of environmental noise levelsfrom the development to determine compli-ance with the consent/licence conditions(Section 11).

1.4.1 Principles underpinning thenoise criteria

The industrial noise source criteria set down inSection 2 are best regarded as planning tools. Theyare not mandatory, and an application for a noise-producing development is not determined purely onthe basis of compliance or otherwise with the noisecriteria. Numerous other factors need to be takeninto account in the determination. These factorsinclude economic consequences, other environmen-tal effects and the social worth of the development.The criteria help to determine consent/licenceconditions because they provide information on thelikely effect of any environmental noise associatedwith the development.

Within the community, there is a very large range ofhuman reaction to noise. There are those in thecommunity who are very sensitive to noise. Thisnoise-sensitive sector of the population will react,often strongly, to intruding noises that are barelyaudible within the overall noise environment, orwill have an expectation of very low environmentalnoise levels. On the other hand, there are thosewithin the community who find living in noisyenvironments, such as near major industry, on mainroads or under aircraft flight paths, an acceptablesituation. The bulk of the population lies withinthese two extremes, being unaffected by low levelsof noise and being prepared to accept levels of noisethat are commensurate with living in an urban,industrialised society.

The criteria in this document (Section 2) have beenselected to protect at least 90 per cent of the popula-tion living in the vicinity of industrial noise sourcesfrom the adverse effects of noise for at least 90 percent of the time. Provided the criteria in this docu-ment are achieved, then it is unlikely that mostpeople would consider the resultant noise levelsexcessive. In those cases when the project-specificnoise levels are not, or cannot be, achieved, then itdoes not automatically follow that those peopleaffected by the noise would find the noise unaccept-able.

1.4.2 Existing versus new development

The assessment procedures in the policy can applyto any one of the following three situations:

• new development impacts—for example, newindustrial premises proposed near anexisting residential area

• modification of an existing development andits impact—for example, proposed expansionof an existing industrial premises

• noise associated with existing development.

Existing noise sources

The application of the criteria to existing sources ofnoise would occur where significant modifications(such as to warrant serious and/or ongoing devel-opment consent or EPA approval) are made toexisting developments or where complaints arereceived.


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In applying the policy to existing operations it isacknowledged that the scope for applying feasibleand reasonable mitigation measures to existingnoise sources is usually far more limited than fornew developments. Careful consideration of noiseimpacts and the feasible and reasonable mitigationmeasures available at these sites may result in lessstringent noise limits than would ideally apply.Sometimes the resultant noise limits will be abovethe criteria. The assessment and management ofexisting premises is dealt with in Section 10.

Greenfield sites

In assessing developments proposed for ‘greenfield’(undeveloped) areas, the policy allows controlledincreases above background noise levels in a similarmanner to previous policy and planning practice.(See case study (a) in Appendix A, Section A2.)

1.4.3 Prevention of noise impacts

Avoiding co-location of incompatible uses

Judicious land use and project planning can oftenprevent potential noise problems from occurring.This policy should be used to consider the implica-tions of proposing or allowing new noise-sensitivedevelopments near noise generators and of propos-ing or allowing new noise-generating developmentsnear established noise-sensitive developments suchas schools, hospitals or homes. The criteria will helpin the first instance to identify sites where it wouldbe difficult, if not impossible, to avoid noise impactsover time, and will therefore help in an informedprocess for making decisions about land-use zoningor site selection by developers.

The criteria can also be used to identify the need forplanning and building-design mitigation measuresfor managing the relationship between noise-generating activities and noise-sensitive develop-ments.

The types of strategies that could be used by plan-ners and project proponents include:

• considering noise impacts when planningthe development of areas, and incorporatingsuitable measures such as:

—spatial separation between noisy activitiesand noise-sensitive areas through locatingless-noise-sensitive land uses (active

recreation areas or access ways) in highnoise areas

—taking advantage of any natural topo-graphical features that can be used toscreen noise impacts when planning landuse in an area

—subdivision layout to maximise the areashielded from noise

—using intervening structures such as multi-level buildings to act as barriers. Buildingsused as barriers should incorporate noise-quietening principles into their buildingdesign to ensure appropriate internalconditions.

• incorporating appropriate building design tominimise noise impacts, for example:

—including acoustic design principles whenplanning landscaping for a site by examin-ing the suitability of earth berms, walls orfences to act as barriers

—building design to locate noise-insensitiveareas such as kitchens, storage areas andlaundries towards the noise source;minimising the size and number of win-dows oriented towards the noise source;replacing conventional roof design witheaves by a flat roof with parapets; usingthe building structure to shield outdoorareas

—using construction techniques that havegood attention to sealing air gaps arounddoors and windows exposed to noise;using solid core doors; and using thickerwindow glass or double glazing.

It is also important that there be a mechanism forproviding information on existing noise impactsfrom approved facilities to members of the publicseeking to move into areas, in order to avoid unreal-istic expectations of noise amenity in affected areas.

1.4.4 Noise criteria and assessment

Two criteria

The policy sets two separate noise criteria to meetenvironmental noise objectives: one to account forintrusive noise and the other to protect the amenityof particular land uses.


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Assessing intrusiveness

For assessing intrusiveness, the background noiseneeds to be measured. An objective procedure isoutlined in Section 3.1.

The intrusiveness criterion essentially means thatthe equivalent continuous (energy-average) noiselevel of the source should not be more than 5 deci-bels (dB) above the measured background level.

Assessing amenity

The amenity assessment is based on noise criteriaspecific to land use and associated activities. (SeeTable 2.1.) The criteria relate only to industrial-typenoise and do not include road, rail or communitynoise. The existing noise level from industry ismeasured. (See Section 3.2.) If it approaches thecriterion value, then noise levels from new indus-tries need to be designed so that the cumulativeeffect does not produce noise levels that wouldsignificantly exceed the criterion. (See Table 2.2.) Forhigh-traffic areas there is a separate amenity crite-rion (Section 2.2.3). The cumulative effect of noisefrom industrial sources needs to be considered inassessing impact (Section 2.2.4).

Project-specific noise levels

For a particular project, the more stringent of theintrusive or the amenity criteria sets the project-specific noise levels for that project. Generally, theintrusive criterion applies for all new industriesuntil an area begins to become more developed,causing increased noise levels. At this stage theamenity criterion starts to take over as the applica-ble criterion. Where several new industries areproposed for a new area, care must be taken toensure that equitable levels are set for each pro-posed industry (Section 2.2.4).

Accounting for annoying noise characteristics

A noise source may exhibit a range of particularcharacteristics that increase annoyance, such astones, impulses, low frequency noise and intermit-tent noise. Where this is the case, an adjustment isapplied to the source noise level received at anassessment point before it is compared with theproject-specific noise level to account for the addi-tional annoyance caused by the particular charac-teristic. Application of these modifying factors isdescribed in Section 4.

Accounting for the effect of meteorology on noiselevels

When assessing noise impacts, the project-specificnoise levels are expected to apply under weatherconditions characteristic of an area. These condi-tions may include calm, wind and temperatureinversions. In this regard, the policy addresses theincrease in noise that results from atmospherictemperature inversions and wind effects.

The policy sets the following procedure for assess-ing temperature inversions (Section 5.2):

• an initial screening test is done to identifywhether any further assessment ofmeteorological effects on noise is warranted

• where the effect is significant, the proponentmay choose to use default meteorologicalvalues to predict the increased noise levels.These defaults have been provided so thatpotentially costly on-site monitoring can beavoided.

• alternatively, the proponent can reject thedefault values and derive parameters bydirect measurement

• the increased noise level is then predictedusing the meteorological parametersestablished.

This procedure is based on an extensive study of theprevalence of temperature inversions and draws onsubstantial field data.

The noise levels predicted under existing meteoro-logical conditions for each receiver are then com-pared with the project-specific noise levels, toestablish whether the meteorological effect willcause a significant impact.

Wind may also increase noise levels downwind ofthe source. The policy specifies a procedure forassessing the significance of wind effects, and adefault wind speed to be used in the assessmentwhere these effects are found to be significant(Section 5.3).

1.4.5 Applying noise mitigation strategies

Where noise impacts are predicted, noise-sourcemanagers should seek to achieve the criteria byapplying feasible and reasonable mitigation meas-


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ures. In this context feasibility relates to engineeringconsiderations and what can practically be built,and reasonableness relates to the application ofjudgement in arriving at a decision, taking intoaccount the following factors:

• noise mitigation benefits—amount of noisereduction provided, number of peopleprotected

• cost of mitigation—cost of mitigation versusbenefit provided

• community views—aesthetic impacts andcommunity wishes

• noise levels for affected land uses—existingand future levels, and changes in noise levels.

A range of mitigation measures is described inSection 7.

1.4.6 Negotiating noise impacts

If, after all feasible and reasonable mitigationmeasures are applied, the resultant noise emissionsexceed the project-specific noise levels, then theresidual level of impact needs to be balancedagainst any social and economic benefits derivedfrom the source of the noise. Negotiation betweenthe regulatory/consent authority, the communityand the proponent to establish achievable noiselimits is described in Section 8. This negotiationprocess is in addition to the direct consultation thatnormally occurs throughout the impact assessmentprocess between the proponent and the community.

1.4.7 Setting noise limits in consent andlicence conditions

In setting noise limits, the regulatory/consentauthorities need to consider the technical practicali-ties of mitigation, the amount of noise reductionprovided, community views, benefits arising fromthe development and cost of achieving the project-specific noise levels recommended here, along withthe environmental consequences of exceeding theproject-specific noise levels. It is important that theproject-specific noise levels are not automaticallyinterpreted as conditions for consent, withoutconsideration of the other factors. In many in-stances, it may be appropriate to set noise limits fora development above the project-specific noise levelsrecommended in this document (Section 9).

1.4.8 Land acquisition

Licences issued by the EPA do not contain condi-tions related to land acquisition.

The noise criteria contained in this document havenot been derived for the purpose of land acquisition.As previously stated they are designed to protectagainst intrusiveness and to preserve amenity, anddrive a process of applying all feasible and eco-nomically reasonable avoidance and mitigationmeasures. To meet these purposes the noise criteriahave been based around identifying the upper(rather than the average) level of impact. They seekto restrict the risk of people being highly annoyed toless than 10 per cent, and to meet this for at least 90per cent of the time.

Resolving noise problems through land acquisitionis viewed as an option of last resort. Where landacquisition is applied, this is done via the develop-ment consent process, which is administered by therelevant planning authority. The developmentconsent may contain conditions related to landacquisition.

The determination of when projected noise levelsare so high and intractable that circumstanceswarrant land acquisition will depend on a range offactors. Noise is only one of those. In some in-stances, disadvantages in one area may be tradedagainst benefits in another area. The weighing-up ofall of the relevant factors is the role of the planningsystem.

It is important to reiterate there is no single identifi-able noise level that all people will find acceptableor unacceptable. Annoyance increases with increas-ing noise, but at any given noise level there will be awide variation in the range of individual reactionsto noise. In extreme cases health can be affected, butgenerally it appears that annoyance can occur wellbefore there is a question of health impact.

The various assessed levels of impact around anindustrial noise source could be described as a zoneof affectation, characterised by annoyance. Withinthis zone could lie a much smaller zone closer in tothe source where impacts were greater and justifiedacquisition of residences. The border between theannoyance and acquisition zones would be repre-sented by a noise level well above both the back-ground level and the EPA’s criteria. If the noise from


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industry were sufficient to alter the character of thearea substantially and/or cause health impacts,then land acquisition might be an option. Landacquisition is rarely a practical approach in heavilydeveloped areas.

1.4.9 Monitoring of noise levels againstconsent or licence conditions

Monitoring of environmental noise levels from adevelopment to determine compliance with thelimits set in consent/licence conditions is essentialfor proper management of noise sources. Proceduresto manage non-compliance with consent/licenceconditions are also provided (Section 11).

1.5 Summary of approach

Figure 1.1 provides an overview of the main proc-esses involved in applying the policy. The flowcharts in Figures 1.2 to 1.6 present a step-by-stepguide to how the policy works, with references torelevant sections in the policy.

Worked case studies outlining the assessmentprocess are set out in Appendix A.


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Figure 1.1. Applying the policy

Project-specific noise levels

Assessment

Mitigation

Decision-making process

Conditions

Monitoring environmental noise performance

Derive project-specific noise levels from applying monitored existing noise levels to the general noisecriteria for intrusiveness and amenity. (See Figure 1.3 for details.)

Proponent estimates likely noise impacts under existing weather conditions (this may includetemperature inversion conditions where they are significant) and includes any adjustment for noise

characteristics.

If project-specific noise levels are exceeded, proponent examines feasible and reasonable mitigationmeasures, considering community preferences, and determines resultant noise levels.

Where resultant noise levels exceed project-specific noise levels, then the regulatory/consentauthority either accepts the resultant level or negotiates if a better level of control is thought

achievable.

Where project-specific noise levels are exceeded, proponent assesses the level of impact bycomparing resultant noise levels against the project-specific noise levels (for example, noise exceedsproject-specific noise levels by X dB, number of people affected, likely impacts on activities, % of time

impact occurs) and factoring-in economic and social benefits from the development.

Consent and licence conditions are set after carefully considering the benefit of full compliance withthe project-specific noise levels, balanced against the overall social, economic and environmentalbenefits of the development. The consent and licence conditions may include the noise limits to be

achieved and other related conditions, but acquisition levels may be included in only the developmentconsent.

Compliance with consent/licence conditions.


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Figure 1.2. The overall process of assessing and managing noise impacts

Section 6.3.1

Noise reduction plan/licenceconditions (Section 10)

Note: Dotted line indicates an optional process

Determine project-specific noiselevels

Figure 1.3 (Section 2)

Predict level of noise from the source anddetermine noise impact

Figure 1.4

(Section 6)

Modifying factors(Section 4)

MeteorologyFigure 1.5

(Section 5)

Consider mitigation options(Section 7)

Acceptable level of impactnegotiated

Figure 1.6

(Section 8)

Noise impactpresent?

YES

NO

Project-specificnoise levels

met?

NO

YES

Consent/licence conditiondetermined Figure 1.6 (Section 9)

Performance monitoring(Section 11)

Existing noise levels(Section 3)

New sitesExisting sites


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Figure 1.3. Determining the project-specific noise levels

Note: Dotted line indicates an optional process

Measure existing noise levels ( Section 3 )

i.e. existing background (LA90) (Section 3.1) andexisting ambient industrial noise (LAeq) (Section 3.2)

Determine representative existing noise levels frommeasured levels ( Section 3 )

i.e. rating background level (RBL) (Section 3.1.2), existingambient level (Section 3.2)

Determine intrusiveness criteria ( Section 2.1 )

i.e. LAeq,15 minute ≤ RBL plus 5 dB

Determine amenity criteria ( Section 2.2 )

1. Determine type of receiver (Table 2.1, Sections 2.2.1 &2.2.2)

2. Determine acceptable noise level (ANL) for receiver, LAeq,period

(Tables 2.1 & 2.2)

3. Amenity criterion is either:

• 'ANL' where existing ambient level is more than 6 dBbelow ANL; or

• '< ANL' where existing ambient level is between ‘ANL+1 dB’ and ‘ANL – 6 dB’; or

• 'existing ambient level minus 10 dB' where existingambient level is greater than ‘ANL+1 dB’ and existingnoise levels are unlikely to decrease in future; or

• 'ANL – 10 dB' where existing ambient level is greaterthan ‘ANL+1 dB’ and existing noise levels are likely todecrease in future; or

• 'existing traffic noise level (LAeq, period) minus 10 dB'where existing traffic noise level is ≥ 10 dB above ANL(high traffic criterion, Section 2.2.3)

Project-specific noise levels applicable to project

The lower of the intrusive criterion andthe amenity criterion.

Where the proponent desires, moredetailed monitoring and analysis linking

existing noise levels and weatherconditions can be made.

(Section 6.3.1)

Determine alternative intrusivenesscriteria for specific weather conditionsidentified in any detailed monitoring

analysis that was done.

Determine alternative amenity criteria forspecific weather conditions identified in

any detailed monitoring analysis that wasdone.


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Figure 1.4. Predicting source noise level and determining impact

Identify noise parameters ( Section 6.1 )

i.e. noise sources, receivers, site features etc

Determine weather conditions relevant to siteunder which criteria apply

(Section 5 )Figure 1.5

e.g. temperature inversions and wind speeds

Predict noise levels from the source ( Section 6 )

Prediction process should take account of all sourceand site parameters and relevant weather

conditions.

Does the noise sourcecontain annoyingcharacteristics?

(Section 4)

Yes

No

Compare predicted noise level with project-specific noise levels

Apply relevantcorrection factor to

predicted noise level(Table 4.1 &Section 4.3 )

Does the predictednoise level exceedthe project-specific

noise levels?

Yes

No

No noise impact expected(Go to Figure 1.6 )

Noise impacts expected(Go to Figure 1.6 )


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Figure 1.5. Assessing the likelihood of wind and temperature inversionsenhancing noise impacts at a site

1 For the purpose of determining the frequency of inversions, night is defined as the period from 1 hour beforesunset to 1 hour after sunrise, taken to be 6 pm to 7 am.

Consider wind and temperature inversions(Section 5 )

Is this > 30% of thetime at night1 in winter?

(Section 5.2)

Do initial screening testAssume specified default values for wind (Section 5.3.2)and temperature inversions (Section 5.2) in the prediction

of noise levels from the source.

Noise impactpredicted?

No

Yes

No further consideration ofweather conditions required

Determine percentage occurrence of temperatureinversions ( Section 5.2 & Appendix C )

Based on existing data (Bureau of Meteorology)or site measurements

No

Yes

No further consideration of windand/or temperature inversions needed

Temperature inversions and associateddrainage wind are a site feature

Noise predictions should take account of temperatureinversions using either default inversion values specified in

Section 5.2 or measured site-specific data

Wind is a site feature

Noise predictions should take account ofwind using wind speeds specified in

Section 5.3.2 or measured site-specific data

Determinepercentage of time

the wind direction isfrom source to

receiver

Is this > 30% of the time inany period and season?

(Section 5.3.1)

Yes

Temperature inversions Wind


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Figure 1.6. Negotiation process and consent/licence limits

No

Yes

Negotiation not required—project-specific noise levelsbecome consent conditions

(Section 9.0 )

Negotiations between proponent andregulator for acceptable level of impact

(Section 8.2 )

Negotiations between proponent and theaffected community for an agreed level of

impact ( Section 8.3 )

Agreed level of impact becomes noiselimit on consent or licence condition

(Section 9 )

Acceptable level of impact becomesnoise limit on consent or licence

condition ( Section 9 )

Project-specific noiselevels exceeded even

with proposedmitigation measures

Or alternatively,

Proponent demonstrates that project- specificnoise levels cannot be feasibly met, andregulator is satisfied that this is the case


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2 Industrial Noise Criteria

The assessment procedure for industrial noisesources has two components:

• controlling intrusive noise impacts in theshort term for residences

• maintaining noise level amenity forparticular land uses for residences and otherland uses.

In assessing the noise impact of industrial sources,both components must be taken into account forresidential receivers, but, in most cases, only onewill become the limiting criterion and form theproject-specific noise levels for the industrial source.The worked case studies in Appendix A show howboth components work together.

The procedures specified in the policy differentiatebetween low- and high-noise-risk developments,with simpler procedures available for developmentswith low noise risk. Differentiation between thesetwo types of developments is on the basis of magni-tude (for example, level of noise expected) andextent of impact (for example, expected area ofaffectation). Hence, a development that is likely tomake excessive noise affecting a large area can beconsidered to be a high-risk development, and viceversa for low risk.

2.1 Intrusive noise impacts

The intrusiveness of an industrial noise source maygenerally be considered acceptable if the equivalentcontinuous (energy-average) A-weighted level ofnoise from the source (represented by the LAeq

descriptor), measured over a 15-minute period, doesnot exceed the background noise level measured inthe absence of the source by more than 5 dB.

To account for the temporal variation of backgroundnoise levels, the method outlined in Section 3.1 isrecommended for determining the backgroundnoise level (rating background level—RBL) to beused in the assessment. This approach aims toresult in the intrusive noise criterion being met for atleast 90% of the time periods over which annoyancereactions can occur (taken to be periods of 15minutes).

Adjustments are to be applied to the level of noiseproduced by the source that is received at theassessment point before comparison with thiscriterion. Where the noise source contains annoyingcharacteristics—such as prominent tonal compo-nents, impulsiveness, intermittency, irregularity anddominant low-frequency content—adjustments asoutlined in Section 4 apply.

Procedures for considering meteorological effectssuch as temperature inversions and wind areoutlined in Section 5 to account for characteristicweather conditions under which the intrusivenesscriterion applies.

The intrusiveness criterion is summarised asfollows:

LAeq, 15 minute ≤ rating background level plus 5

where :LAeq, 15 minute represents the equivalentcontinuous (energy average) A-weightedsound pressure level of the source over 15minutes. Other descriptors may be used asappropriate provided they can be justifiedon the basis of being characteristic of thesource (see Section 2.3). This is to beassessed at the most-affected point on orwithin the residential property boundary—or, if that is more than 30 m from theresidence, at the most-affected point within30 m of the residence.

Rating background level is the backgroundlevel to be used for assessment purposes asdeter-mined by the method outlined in Section3.1.

A 15-minute sampling period is used when measur-ing the level of intrusive noise. There has been nodefinitive research to quantify the time period overwhich annoyance to intrusive noise varies. Clearly,annoyance reactions are likely to occur over periodsof less than a day, and there will be variationsdepending on individual tolerance and characteris-tics of the noise. The 15-minute period has beenselected as a reasonable estimate of the period overwhich annoyance may occur. This time period hasbeen used by the EPA for some time, and experience


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has shown that it is a reasonable approach toassessing intrusive noise impacts.

In some rural situations, the rating backgroundlevel may be the same for the day and night. In thesecases, it is recognised that excursions of noise abovethe intrusiveness criterion during the day wouldnot usually have the same impact as they would atnight. This is due to the more sensitive nature ofactivities likely to be disturbed at night (for example,sleep and relaxation).

2.2 Protecting noise amenity

To limit continuing increases in noise levels, themaximum ambient noise level within an area fromindustrial noise sources should not normallyexceed the acceptable noise levels specified in Table2.1. Meeting the acceptable noise levels in Table 2.1will protect against noise impacts such as speechinterference, community annoyance and, to someextent, sleep disturbance. These levels representcurrent best practice for assessing industrial noisesources, based on research and a review of assess-ment practices used overseas and within Australia.

Table 2.1 also includes recommended maximumnoise levels for different land uses. These recom-mended maximum values provide guidance on anupper limit to the level of noise from industry. In allcases it is expected that all feasible and reasonablemitigation measures would be applied before therecommended maximum noise levels are referenced.

In some instances it may not be possible to achieveeven the recommended maximum noise level, evenafter all feasible and reasonable noise mitigationhas been applied. Such cases are expected to have alarge adverse noise impact. Where a proposeddevelopment exceeds the recommended maximumnoise levels in Table 2.1, substantial benefits in otherareas, including a high degree of social worth,would need to be demonstrated.

Where the existing noise level from industrial noisesources is close to the acceptable noise level, thenoise level from any new source(s) must be control-led to preserve the amenity of an area. If the totalnoise level from industrial sources already exceedsthe acceptable noise level for the area in question,the LAeq noise level from any new source should notbe greater than:

• 10 dB below the acceptable noise level if thereis a reasonable expectation that existinglevels may be reduced in the future; or

• 10 dB below the existing level if there is nosuch reasonable expectation that existinglevels will fall (for example, in cases wheresurrounding areas are fully developed) andno significant changes to land use areexpected.

Table 2.2 sets out the implications of this require-ment for noise from industrial sources.

Adjustments are to be applied to the source noiselevel received at the assessment point, before com-parison with this criterion, where the noise sourcecontains annoying characteristics such as promi-nent tonal components, impulsiveness, intermit-tency, irregularity and dominant low-frequencycontent, as outlined in Section 4.

Procedures for considering meteorological effectssuch as temperature inversions and wind areoutlined in Section 5 to account for characteristicweather conditions under which the amenitycriteria apply.

In determining the existing LAeq noise level fromindustry, noise from transportation-related sources(road traffic, rail traffic and aircraft) may be ex-cluded. Criteria for noise from these sources aredefined separately. Research and experience indi-cates that residents distinguish and respondseparately to noise from road traffic, rail traffic,aircraft and industrial sources, rather than register-ing an overall noise annoyance related to the totalLAeq noise level. Section 3.2 gives guidance on how todetermine existing noise levels. Practical means bywhich transportation noise (road traffic in particu-lar) may be excluded from a measurement of exist-ing noise levels are presented in Section 3.2.1.

Where existing traffic noise levels are continuouslyhigh, the existing level of the traffic noise (deter-mined by using the method outlined in Section 3.2)can be 10 dB or more above the recommendedacceptable noise level shown in Table 2.1. In thesesituations the industrial source may be inaudible,even where it produces noise levels higher than theacceptable noise level. The criterion to be applied inthis case is set out in Section 2.2.3.


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Table 2.1. Amenity criteria

Where there is a reasonable expectation that thecumulative noise level from industrial sourcescould increase in future (for example, through thedevelopment of further new sources), this should beconsidered in setting noise levels, as outlined inSection 2.2.4.

Recommended L Aeq noise levels from industrial noise sources

Type of Receiver IndicativeNoise Amenity

Area

Time of Day Recommended L Aeq. Noise Level,dB(A)

(see Note 8 in Section 2.2.1)

(see Notes in Section 2.2.1)Acceptable

(See Note 11)

RecommendedMaximum

(See Note 11)

Day 50 55

Evening 45 50

Rural

Night 40 45

Day 55 60

Evening 45 50

Suburban

Night 40 45

Day 60 65

Evening 50 55

Urban

Night 45 50

Day 65 70

Evening 55 60

Residence

Urban/IndustrialInterface – forexistingsituations only Night 50 55

School classroom—internal All Noisiest 1-hour periodwhen in use

35(See Note 10)

40

Hospital ward—internal—external

AllAll

Noisiest 1-hour periodNoisiest 1-hour period

3550

4055

Place of worship—internal All When in use 40 45

Area specifically reserved forpassive recreation (e.g.National Park)

All When in use 50 55

Active recreation area (e.g.school playground, golfcourse)

All When in use 55 60

Commercial premises All When in use 65 70

Industrial premises All When in use 70 75


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Table 2.2. Modification to acceptable noise level (ANL)* to account for existing levelof industrial noise

difficult, then external noise levels 10 dBabove the internal levels apply.

5. In assessing noise levels at passive andactive recreational areas, the noise level is tobe assessed at the most-affected point within50 m of the area boundary.

6. Types of receivers are defined as follows.Section 2.2.2 offers some guidance for theselection of the appropriate receiver types.

Rural—means an area with an acousticalenvironment that is dominated by naturalsounds, having little or no road traffic. Suchareas may include:

—an agricultural area, except those used forintensive agricultural activities

—a rural recreational area such as resortareas

—a wilderness area or national park

—an area generally characterised by lowbackground noise levels (except in theimmediate vicinity of industrial noisesources).

This area may be located in either a rural,rural-residential, environment protection

Total existing L Aeq noise level fromindustrial sources, dB(A)

Maximum L Aeq noise level for noise from new sourcesalone, dB(A)

≥ Acceptable noise level plus 2 If existing noise level is likely to decrease in future:acceptable noise level minus 10

If existing noise level is unlikely to decrease in future:existing level minus 10

Acceptable noise level plus 1 Acceptable noise level minus 8

Acceptable noise level Acceptable noise level minus 8

Acceptable noise level minus 1 Acceptable noise level minus 6






< Acceptable noise level minus 6 Acceptable noise level* ANL = recommended acceptable LAeq noise level for the specific receiver, area and time of day from Table 2.1.

2.2.1 Notes to support the noise leveltables

1. The recommended acceptable noise levelsrefer only to noise from industrial sources.However, they refer to noise from all suchsources at the receiver location, and not onlynoise due to a specific project under consid-eration. The levels represent outdoor levelsexcept where otherwise stated.

2. In assessing noise levels at residences, thenoise level is to be assessed at the most-affected point on or within the residentialproperty boundary or, if this is more than 30m from the residence, at the most-affectedpoint within 30 m of the residence.

3. In assessing noise levels at commercial orindustrial premises, the noise level is to beassessed at the most-affected point on orwithin the property boundary.

4. Where internal noise levels are specified inTable 2.1, they refer to the noise level at thecentre of the habitable room that is mostexposed to the noise and are to apply withwindows opened sufficiently to provideadequate ventilation. In cases where thegaining of internal access for monitoring is


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zone or scenic protection zone, as definedon a council zoning map (Local Environ-mental Plan (LEP) or other planninginstrument).

Suburban—an area that has local traffic withcharacteristically intermittent traffic flows orwith some limited commerce or industry. Thisarea often has the following characteristics:

—decreasing noise levels in the eveningperiod (1800–2200); and/or

—evening ambient noise levels defined by thenatural environment and infrequenthuman activity.

This area may be located in either a rural,rural-residential or residential zone, asdefined on an LEP or other planninginstrument.

Urban—an area with an acoustical environ-ment that:

—is dominated by ‘urban hum’ or industrialsource noise

—has through traffic with characteristicallyheavy and continuous traffic flowsduring peak periods

—is near commercial districts or industrialdistricts

—has any combination of the above,

where ‘urban hum’ means the aggregatesound of many unidentifiable, mostlytraffic-related sound sources.

This area may be located in either a rural,rural-residential or residential zone asdefined on an LEP or other planninginstrument, and also includes mixed land-use zones such as mixed commercial andresidential uses.

Urban/industrial interface—an area definedas for ‘urban’ above that is in close proximityto industrial premises and that extends out toa point where the existing industrial noisefrom the source has fallen by 5 dB. Beyondthis region the amenity criteria for the ‘urban’category applies. This category may be usedonly for existing situations. (See example ofhow this category is used in Appendix A,Section A5).

Commercial—an area defined as a businesszone, except neighbourhood business zone,on an LEP.

Industrial—an area defined as an industrialzone on an LEP. For isolated residenceswithin an industrial zone the industrialamenity criteria would usually apply.

7. Time of day:

—day: the period from 7:00 am to 6:00 pmMonday to Saturday; or 8:00 am to 6:00 pmon Sundays and public holidays

—evening: the period from 6:00 pm to 10:00pm

—night: the remaining periods.

(These periods may be varied whereappropriate, for example, see Section 3.3.)

8. The LAeq noise level for a specific periodrepresents the LAeq level calculated or meas-ured over the applicable day, evening ornight period (i.e. LAeq, period) except whereotherwise stated (for example, school class-room, hospital).

9. If existing noise levels from industrial noisesources already approach or exceed therecommended acceptable noise levels in Table2.1, any increase in these levels should bestrictly limited, as described in Table 2.2.

10. In the case where existing schools are af-fected by noise from existing industrial noisesources, the acceptable LAeq noise level maybe increased to 40 dB LAeq(1hr).

11. The acceptable and recommended maximumLAeq noise levels can provide a guide toapplying the negotiation process set out inSection 8. While negotiation between theproponent and the community for an agreednoise level can occur at any time, typicallythe proponent would negotiate with the EPAwhere noise-level emissions fall between theacceptable and recommended maximum. Forsite levels beyond the recommended maxi-mum levels, the proponent would need tonegotiate directly with the community.

2.2.2 Determining the receiver type

The selection of the type of receiver is important indetermining which noise amenity criteria levelshould apply. In most instances the receiver cat-


19

egory for the amenity criteria will be straightfor-ward, but in some localities, land-use patterns orzones may be ambiguous in terms of selecting theappropriate receiver type. As a guide the followingissues may be considered in deciding the land usecategory for a receiver:

• The primary means for identifying the type ofreceiver is how the receiver area is zoned inthe relevant planning instrument. Thestandard terminology used in planninginstruments is usually limited to rural, rural-residential and residential in respect of areaswhere dwellings would normally be located.These terms do not differentiate suburbanand urban residential uses, and this isdiscussed in the next point.

• In deciding whether a receiver area should beallocated to the suburban or urban categories,it may be necessary to examine thepredominant manner of development in thearea and the prevailing noise climate. Thedefinitions of suburban and urban provideguidance on this. For example, smallcommunities such as villages or towns arelikely to be closer in noise climate to asuburban category. Urban receivers areusually those located in densely populatedareas where multi-dwelling developmentssuch as townhouses, units, flats andapartments are the norm. Areas near noisegenerators (for example, roads, railways andindustry) would normally be considered to beurban-receiver type for the purpose of theamenity criteria. The rural category is morerepresentative of more isolated singledwellings on large lots (for example, 2hectares). The population density for an areamay provide a guide as to which of theresidential receiver categories apply.

• In certain instances zoning for an area willallow multiple uses. For instance, some areasare classified as ‘Rural’ with industry-relatedland uses permissible, thus allowing ruraluses (including a dwelling) and industries inthe same area. In terms of noise thepermissible uses may not be entirelycompatible, and where this mix ofdevelopment is permitted it may not alwaysbe possible to achieve the desirable noisecriteria for receivers. In these instances thenoise levels that are achievable will be

defined by applying all feasible andreasonable mitigation measures. It is highlyrecommended that the relevant consentauthority consider the need to incorporatenoise mitigation measures in noise-sensitivedevelopments where such mixeddevelopment is permitted (for example, newresidences proposed near industrial orcommercial areas).

• Other features of a locality that should alsobe considered include:

—predominant land use, including theproportion of the different land useswithin the potentially noise-affected zone

—strategic planning objectives or plans torezone (for example, as included in REPs,SEPs, Urban Development Program)

—proximity of land-use to neighbouringindustries and busy roads

—any permanent existing shielding providedby natural topography or otherwisebetween existing noise sources and sensi-tive receivers

—existing ambient noise levels in the area.

2.2.3 Assessment in areas of high trafficnoise

The level of transportation noise—road traffic noisein particular—may be high enough to make noisefrom an industrial source effectively inaudible, eventhough the LAeq noise level from that industrialnoise source may exceed the recommended accept-able noise level shown in Table 2.1. In such cases,the amenity criterion for noise from the industrialnoise becomes the LAeq, period(traffic) minus 10 dB. Thiscriterion replaces the amenity criterion in Tables 2.1and 2.2 above, and is used in the same way theamenity criterion is used, that is, in conjunctionwith the intrusiveness criterion, to determine thelimiting criterion. General and more specific casestudies showing how the high traffic criterionworks are included in Appendix A. (See Section A1and case study (c) in Section A2.)

This criterion may be applied only if all the follow-ing apply:

1. Traffic noise is identified as the dominantnoise source at the site.


20

2. The existing traffic noise level (determinedusing the procedure outlined in Section 3.2) is10 dB or more above the Acceptable noiselevel for the area.

3. It is highly unlikely the road traffic noiselevels would decrease in the future.

In all other cases the existing noise level of indus-trial sources may be determined by one of themethods outlined in Section 3.2.1 for comparisonwith Table 2.2 in the determination of the amenitycriterion.

This method needs to be used with care for differentassessment periods. For example, although thiscriterion may be valid in high-traffic areas for the‘day’ assessment period, it may not be appropriatefor the ‘evening’ or ‘night’ assessment periodsbecause the requirement in (2) above has not beenmet. Where this is the case, one of the methodsoutlined in Section 3.2.1 may be used for the eveningand night periods.

2.2.4 Assessment in developing areas

The recommended acceptable noise level from Tables2.1 and 2.2 represents the ideal total level of noisefrom industry that should be met by a proposeddevelopment and any future, potentially noise-producing, developments in the area. In mostinstances where a number of industrial develop-ments are proposed for an area, the amenity criteria,which set a cap for the cumulative noise fromindustry, will be more stringent than the intrusivecriteria. Thus project-specific noise levels for indi-vidual developments will be derived from theamenity criteria.

Where several developments are proposed for anarea, these are to be assessed as a group. Thisholistic approach allows project-specific noiselevels to be set for a proposed industrial develop-ment, so that the total impact from all proposed andpotential industrial developments does not causeamenity to deteriorate. In addition, this approachprovides an equitable distribution in the burden ofmeeting the noise criteria.

The effectiveness of this approach depends on itbeing known at the time of assessment what devel-opments will be moving into the locality, and whenthe various developments are proposed to com-mence. Generally, the approach should apply whenknowledge of future developments has advanced to

the point of a development application beingknown to the regulatory/consent authority, orwhere details of the proposal have been published.

Implementation of this ‘holistic’ approach involvesthe following steps in relation to impacts at the mostsensitive receivers:

1. Determining the number of developmentproposals to be assessed.

2. Determining the amenity level according toTables 2.1 and 2.2.

3. Determining the project-specific noise levelsto be achieved by each development at thereceiver, so that, when each is added logarith-mically, the resultant total level of noisereceived from industry at any affected re-ceiver will meet the amenity level identified atStep 2.

As the assessment is performed at the receiver, thelevel of noise received from each developmentdepends on its distance from the receiver—withmore remote developments able to emit higher noiselevels at the source.

This type of approach has been applied by someforward-thinking local councils to provide an earlyindication to potential developers of expected noise-emission requirements, and to guarantee the noiseamenity in adjacent areas. (Examples of where thisapproach has been used include Ingleburn indus-trial estate, Campbelltown; Glendenning industrialestate, Blacktown and Breamer industrial estate,Mittagong.)

2.2.5 Effects of changing land use

Land uses can change—sometimes dramatically—with an increase in industrial activities, construc-tion of new freeways, or the development of newresidential suburbs. A consequence of this is thatthe land-use designation of an area may change.Changes in designation occur as a result of urban-type residential subdivisions in a village or ruralarea with few residences, or the encroachment ofindustrial developments near residential areas andvice versa.

In such cases, the primary decision by planningauthorities to cause or allow the developmentwould take account of the many consequent impli-cations. As developments introduce increased


21

activities, they also increase environmental noiselevels. Therefore, previously low ambient noiselevels will not be maintained, and assessments ofnoise sources for control purposes should be madeagainst the acceptable noise level relevant to themodified land use.

2.3 Using the L Aeq descriptor

The LAeq, descriptor applies for both the intrusive-ness criterion (LAeq, 15 minute) and the amenity criterion(LAeq, period). In this policy, the equivalent continuous(energy average) level (A-weighted) of the industrialsource is of interest (not necessarily that of the totalnoise environment). In certain circumstances othernoise descriptors may be more appropriate formeasurement/assessment or compliance purposes,depending on the characteristics of the noise source.For example, where the noise emissions from thesource of interest are constant (e.g. fan noise) andthe ambient noise level has a degree of variability(for example, due to traffic), the LA90 descriptor mayadequately describe the noise source and be mucheasier to measure/assess. In these cases, it may bepreferable to replace the LAeq descriptor.

If the descriptor chosen for measurement is not theLAeq, reasons for the variation should be presentedin the noise assessment report.

2.4 Project-specific noise levels

After determining the relevant noise levels from theintrusive and amenity criteria, the project-specificnoise levels can be assigned.

The project-specific noise levels reflect the moststringent noise level requirement from the noiselevels derived from both the intrusive and amenitycriteria. They set the benchmark against whichnoise impacts and the need for noise mitigation areassessed.

Applying the most stringent requirement as theproject-specific noise levels ensures that bothintrusive noise is limited and amenity is protected.

The case studies presented in Appendix A showdefinitively how project-specific noise levels areidentified.


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3.1.1 Methods of determining backgroundnoise

Table 3.1 summarises the two procedures for deter-mining background noise: the long-term method tobe used at the planning and approval stage, and theshort-term method for complaint and complianceassessment purposes. The long-term method in-volves a two-step process to determine the ratingbackground level. The short-term method involvesonly one step. Appendix B gives a detailed descrip-tion of instrumentation requirements, and proce-dures for measurement and analysis for eachmethod.

The long-term method for determining backgroundnoise (summarised in Table 3.1) is designed toensure that the criterion for intrusive noise will beachieved for at least 90% of the time periods overwhich annoyance reactions may occur (taken to beperiods of 15 minutes).

Definitions and technical considerations to helpusers interpret and apply the methods are set downin the following sections.

3.1.2 Definitions to support methodologies

Extraneous noise—noise due to activities that arenot typical of the area. These activities might includeconstruction, changes in road, rail or air traffic dueto holiday periods, and special events such asconcerts or sporting events. Normal daily roadtraffic and other transportation noise are not consid-ered to be extraneous noise. Where an industry in anindustrial estate wishes to extend its operations, themeasured background noise level may include thegeneral hum of industries nearby, but should notinclude any noise from the site itself—or noise fromany intrusive sources nearby that could affect theLA90,15 minute value. As a reasonable guide, any extra-neous noise present for at least half of a 15-minutemonitoring period, and having the potential to affectthe LA90,15 minute value, should be excluded.

3 Determining existing noise levels

3.1 Determining background noise forthe intrusiveness criterion

The background noise level is defined here as ‘theunderlying level of noise present in ambient noisewhen all unusual extraneous noise is removed’.Sound levels contributing to background levels caninclude sound from nearby traffic (see Section 3.1.3),birds, insects, animals, machinery and similarsources if these sounds are a normal feature of thelocation. The background noise level is consideredto be represented by the LA90,15 minute descriptor. Incomparison, the rating background level (as definedin Section 3.1.2) is the single-figure backgroundnoise level derived from monitoring LA90, 15 minutes overa representative period of time. The rating back-ground level is used for assessment purposes.

Background noise levels need to be determinedbefore intrusive noise can be assessed. The back-ground noise levels to be measured are those thatare present at the time of the noise assessment andwithout the subject development operating. Hence,for the assessment of modifications to an existingdevelopment, the noise from the existing develop-ment should be excluded from background noisemeasurements.

When assessing a new development, it is importantto undertake sufficient monitoring of backgroundnoise to allow intrusive noise to be assessed ad-equately. However, when assessing noise levels inresponse to complaints, the background noise levelduring the period of the complaint is of interest, andmonitoring over a shorter length of time may beappropriate.

Before embarking on a noise-monitoring program,the potential for the development/ activity to causenoise annoyance, and the need for accurate noiseassessment, should be considered. Two measure-ment regimes are presented below. The first is adefinitive method to be used when assessing devel-opments with the potential for significant noiseimpact. The second is a shorter method that can beused for complaint-assessment purposes.


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Table 3.1. Methods for determining background noise

Features Method

Long-term Short-term

When to use During planning and approval stagewhere there is significant potential fornoise impact, e.g. extractive industriesand industrial developments.

During complaint assessments, compliancechecks, when determining the effect ofbackground noise on a source noisemeasurement and for low riskdevelopments.

Type of monitoring Continuous sampling accompanied byperiods of operator-attended monitoring

Individual sampling—operator-attendedmeasurements

Length ofmonitoring

Equivalent to one week’s worth of validdata covering the days and times ofoperation of the development (SeeSection 3.5)

15-minute measurements covering thetimes of operation of the development

Conditions formonitoring

Average wind speed < 5 m/s1, no rain, noextraneous noise (See Sections 3.1.2and 3.4)

Average wind speed < 5 m/s1, no rain, noextraneous noise (See Sections 3.1.2 and3.4)

Monitoring location Most or potentially most affected noise-sensitive location/s

Most affected noise-sensitive locationand/or location of complaint

Assessment timeperiods

Day (0700–1800)

Evening (1800–2200)

Night (2200–0700)

(See Section 3.3 for exceptions)

Times when maximum impacts occur

Base measure LA90,15 minute LA90,15 minute

Analysis method Determine the assessment backgroundlevel for each day, evening and night byusing the tenth percentile method.

The rating background level is themedian assessment background levelover all days for each period.

The rating background level is themeasured LA90,15 minute value, or, where anumber of measurements have beenmade, the lowest LA90, 15 minute value.

Note:1. Refers to the wind speed at the microphone height.


24

Special care needs to be taken when doing short-term measurements to ensure that the measurementsreflect the time of maximum impact. For example, ina residential neighbourhood, short-term noisemeasurements should not be taken when there areother noisy activities going on (for example, lawn-mowing, idling vehicles, neighbourhood chatter).When in doubt as to whether an activity is typical ofthe area, it is best to exclude data affected by noisefrom that activity.

Noise-sensitive location(s)—residential premises,schools, hospitals, places of worship, parks andwilderness areas.

Most affected location(s)—locations that are mostaffected (or that will be most affected) by noise fromthe source under consideration as per Note 2 inSection 2.2.1. In determining these locations, thefollowing need to be considered: existing back-ground levels, noise source location/s, distancefrom source/s (or proposed source/s) to receiver,and any shielding (for example, building, barrier)between source and receiver. Often several locationswill be affected by noise from the development. Inthese cases, locations that can be considered repre-sentative of the various affected areas should bemonitored.

Time of maximum impact—the time during whichthe difference between the background noise leveland the source noise is expected to be the greatest.

Assessment background level (ABL)—the single-figure background level representing each assess-ment period—day, evening and night (that is, threeassessment background levels are determined foreach 24-hour period of the monitoring period).Determination of the assessment background levelis by the tenth percentile method described inAppendix B. Only those days and assessmentperiods that are applicable to the times of opera-tion of the proposed development are required tobe assessed.

Rating background level (RBL)—the overall single-figure background level representing each assess-ment period (day/evening/night) over the wholemonitoring period (as opposed to over each 24-hourperiod used for the assessment background level).The rating background level is the level used forassessment purposes. Where the rating backgroundlevel is found to be less than 30 dB(A), then it is setto 30 dB(A).

For the short-term method the rating backgroundlevel is simply the measured LA90,15 minute level. Forthe long-term method, the rating background level isdefined as the median value of:

—all the day assessment background levelsover the monitoring period for the day

—all the evening assessment backgroundlevels over the monitoring period for theevening, or

—all the night assessment background levelsover the monitoring period for the night.

‘Median’ is the middle value in a number of values.For an odd number of values, the value of themedian is simply the middle value in a number ofvalues ranked in ascending or descending order.For an even number of values, the median is thearithmetic average of the two middle values.

3.1.3 Transportation noise in backgroundnoise measurements

Transportation noise (air, road and rail) may beincluded in background noise measurements,except when there is a reasonable expectation thatflows are not representative of normal conditions(for example, traffic during school holidays). Air,road and rail traffic during these times are usuallyconsidered to be extraneous.

Where the period of measurement is limited (that is,short-term measurement), care is needed to ensurethat the time at which the measurements are madereflects the period when the highest noise impactsare likely to occur. For example, where there is onlyintermittent traffic, the short-term noise measure-ment should not include transportation noise,otherwise incorrect high readings will result.However, where the traffic is constant and continu-ous, transportation may be included in the short-term measurement to ensure that the noise environ-ment is adequately represented.

3.2 Determining existing noise levelsfor amenity criteria

Existing noise levels need to be determined for theperiods during which the proposed developmentwill operate.

In determining the existing LAeq noise level, it isimportant to obtain a representative level. Hence,


25

assessing the existing LAeq noise level is as definedin Table 3.2 for assessing different noise risk devel-opments.

3.2.1 Excluding transportation noise

The ‘existing noise levels’ described in Table 2.2 arefor industrial noise sources only. Where practicable,noise from transportation or community activitiescan be excluded, as the measured industry noiselevel will be used (Table 2.2) to determine the amen-ity level. Practical ways of excluding transportationand community noise will depend on the situation.The policy does not require transportation andcommunity noise to be excluded when determiningexisting noise levels, but it may be advantageous tothe proponent to minimise the effects of communityand transportation noise. Possible techniques to dothis include:

1. Measuring the level of transportation noise ata nearby location not affected by noise fromindustry, and logarithmically subtracting thismeasurement from the combined level at thesite. This may be done by setting up twologgers (or two sound-level meters in the caseof short-term measurements) to monitorsimultaneously the combined noise levels atthe site and the transportation noise levels atthe nearby location.

2. Measuring at another location where indus-trial source noise levels are equivalent, buttransportation noise is much lower.

3. Modelling the level of transportation noiseand subtracting the result from the measuredcombined levels.

Table 3.2. Determining the existing LAeq noise levels

4. (Where it can be demonstrated that allexisting noise is due to transportation-relatedsources) Assuming that the level of industrialnoise is 10 dB below the existing combinednoise levels.

When measuring existing industrial noise, takespecial care when determining what constitutes anindustrial noise source. For example, any mobile/transportation sources that form part of the normaloperations on an industrial noise source site areconsidered to be part of the industrial noise sourceand should be included when measuring existingnoise levels from that industrial source.

Where dominant road traffic is over 300 m awayfrom the site and is heard as a very distant hum, thelevel of traffic noise is likely to be low enough thatspecial techniques to minimise its effects are notwarranted. Exceptions to this include cases where amajor road is in direct line-of-sight of the assess-ment position, causing traffic on it to be the domi-nant source of noise at the site.

3.3 Dealing with ‘shoulder’ periods

There will be situations that call for different assess-ment periods. For example, where early morning(5 am to 7 am) operations are proposed, it may beunduly stringent to expect such operations to beassessed against the night-time criteria—especiallyif existing background noise levels are steadilyrising in these early morning hours. In these situa-tions, appropriate noise level targets may be negoti-ated with the regulatory/consent authority on acase-by-case basis. As a rule of thumb it may beappropriate to assign a shoulder period rating

Risk of noise impact Measurement period 1 Definition of existing level

Low risk One day—covering the definedday/evening/night periods relevant to theperiods the proposed development wouldoperate.

High risk One week—covering the definedday/evening/night periods the proposeddevelopment would operate.

The logarithmic average2 ofindividual LAeq,15 minute levels for eachday/evening/night assessmentperiod over the measurementperiod.

Notes:1. It is recommended that the LAeq be measured on a 15-minute basis.2. Logarithmic average = 10log10((∑i=1 to n10(LAeq,15 min,i/10))/n), where n = number of LAeq,15 min values in each

assessment period over the measurement period.


26

background level as the mid-point value betweenthe rating background levels of the two assessmentperiods that are on either side of the shoulderperiod.

The objective is to achieve environmental amenity ina feasible and reasonable manner. In an assessmentof the likely level of noise impact, the time of day isonly one of several relevant factors—such as noiselevel and character, and the activities affected by thenoise. Noise of a lower level, and with no intrusivecharacteristics such as tones and impulses, canoften be more acceptable over a longer period of theday than noise at a high level and/or with intrusivecharacteristics.

3.4 Meteorological conditions formonitoring

Wind and rain conditions

Noise monitoring should not be conducted (or thedata should be excluded) when average windspeeds (over 15-minute periods or shorter) at micro-phone height are greater than 5 m/s, or whenrainfall occurs. Exceptions to this rule are allowed,provided the proponent is able to show that thewind-induced noise on the microphone, and soundlevels due to rain, are at least 10 dB below the noiselevels (that is, background and/or ambient) underinvestigation.

Where high wind speeds are a feature of the area,monitoring may be permitted during higher windspeeds, provided the proponent is able to show thatthese wind speeds are a site feature and that thewind-induced noise on the microphone is at least 10dB below the noise levels under investigation.

Wind blowing through leaves can raise the environ-mental noise levels, even at speeds less than 5 m/s.To avoid this effect, take care to select monitoringlocations that are as far away as possible fromvegetation while still being representative of thesubject site.

Temperature inversions

The noise levels determined using the methods justdescribed are considered to represent the season inwhich they have been monitored. For this reason,monitoring may be conducted during temperature

inversion conditions to ensure that the noise envi-ronment at a site is adequately represented. How-ever, care is needed when doing short-term meas-urements to ensure that the measured noise levelresults in an adequate assessment of impacts. Forinstance, measurement of short-term backgroundnoise should exclude any data collected duringtemperature inversions where these inversions areinfrequent and are not a feature of the area. Other-wise assessment applying the intrusiveness crite-rion will not adequately assess the noise impact.

Seasonal variations

The EPA recognises that background noise levelsmay vary due to seasonal changes in weatherconditions and wildlife activity (for example,insects, birds and other fauna) and also as a resultof changes in operational activities on surroundingdevelopments. As far as is practicable, these poten-tial changes should be considered and addressed ina qualitative manner in the noise assessment reportto ensure that noise impacts during other seasonsare not ignored.

Such changes may be accounted for by excludingthe season-related noise levels from the backgroundnoise measurements by filtering or other means (forexample, in the case of seasonal operational activi-ties, by monitoring in a similar location not affectedby the development in question). In other casesthese variations may be discounted on the basis oflocal knowledge in the area, but the discountingshould still be justified in the noise assessmentreport.

3.5 Duration of monitoring

Screening tests may be performed before any moni-toring to assess whether monitoring is required. Forexample, if a minimum background noise level of 30dB(A) is assumed as the rating background leveland the assessment shows no impact, then there isno need for background noise monitoring, as thisrepresents a conservative and limiting case.

Typically, one week’s worth of valid data coveringthe days and times of operation of the proposeddevelopment is required to meaningfully determinethe existing noise environment. However, theduration of monitoring should be determined bytaking into account the circumstances of the par-ticular situation. The cyclic or random nature of


27

ambient noise levels can affect the duration re-quired.

In areas where the background noise levels areaffected significantly by nearby road traffic withregular daily pattern, three days’ worth of validdata may be sufficient. However, care should beexercised in assuming a pattern of noise levels in anarea. It is recommended that , where any doubtexists, the full week’s monitoring should be per-formed. In those cases where there appears not to bea regular daily pattern to ambient noise, and/or thedominant ambient noise sources are some signifi-cant distance from the measurement location, oneweek’s valid data is likely to be required. There willalso be some circumstances where more than oneweek of valid data will be required to gain a goodunderstanding of the variation in ambient noise (forexample, where there is a wide variability in dailyassessment background levels). Any variations fromthe specified monitoring duration in Table 3.1should be fully justified in the noise assessmentreport.


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4 ‘Modifying factor’ adjustments4.1 Introduction

Where a noise source contains certain characteris-tics, such as tonality, impulsiveness, intermittency,irregularity or dominant low-frequency content,there is evidence to suggest that it can cause greaterannoyance than other noise at the same noise level.On the other hand, some sources may cause lessannoyance where only a single event occurs for alimited duration. This section outlines the correctionfactors to be applied to the source noise level at thereceiver before comparison with the criteria speci-fied in Section 2 to account for the additional annoy-ance caused by these modifying factors. The correc-tion factors listed below were determined followinga review of Australian and overseas practices andthe relevant literature.

The modifying factor corrections should be appliedhaving regard to:

• noise from all sources, individually and incombination, that contribute to the total noiseat a site; and

• the nature of the noise source and itscharacteristics.

Table 4.1 sets out the corrections to be applied. Thecorrections specified for tonal, impulsive, intermit-tent and low-frequency noise are to be added to themeasured or predicted noise levels at the receiverbefore comparison with the criteria.

4.2 Definitions to support themodifying factor corrections

Tonal noise—containing a prominent frequencyand characterised by a definite pitch.

Low-frequency noise—containing major compo-nents within the low frequency range (20 Hz–250Hz) of the frequency spectrum.

Impulsive noise—having a high peak of shortduration or a sequence of such peaks.

Intermittent noise—the level suddenly drops to thatof the background noise several times during theassessment period, with a noticeable change innoise level of at least 5 dB.

Adjustment for duration—applied where a single-event noise is continuous for a period of less thantwo and a half hours in any 24-hour period. Theacceptable noise level may be increased by theadjustment shown in Table 4.2. This adjustment isdesigned to account for unusual and one-off events,and does not apply to regular high-noise levels thatoccur more frequently than once per day.

Maximum adjustment—the maximum correction tobe applied to the criteria or the measured levelwhere two or more modifying factors are present.The maximum adjustment is 10 dB(A) where thenoise contains two or more modifying factors(excluding the duration correction).

4.3 Applying the modifying factors

The modifying factors are to be applied to the noisefrom the source measured/predicted at the receiverand before comparison with the criteria. The modi-fying factor correction is applied as follows (Ki isequal to the modifying factor correction (from Table4.1)):

Where two or more modifying factors are present,the maximum correction is limited to 10 dB.

CompareCriterion

Measured orPredicted

CriterionValue

Intrusiveness LAeq, 15 minute plus Ki Ratingbackgroundlevel plus 5

Amenity(including hightraffic criterionSection 2.2.3)

LAeq, period plus Ki Acceptablenoise level


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Table 4.1. Modifying factor corrections(See definitions in Section 4.2)

Factor Assessment/measurement

When to apply Correction 1 Comments

Tonal noise One-third octaveor narrow bandanalysis

Level of one-third octave bandexceeds the level of theadjacent bands on both sidesby:—5 dB or more if the centrefrequency of the bandcontaining the tone is above400 Hz—8 dB or more if the centrefrequency of the bandcontaining the tone is 160 to400 Hz inclusive—15 dB or more if the centrefrequency of the bandcontaining the tone is below160 Hz

5 dB2 Narrow-bandfrequency analysismay be required toprecisely detectoccurrence

Lowfrequencynoise

Measurement ofC-weighted andA-weighted level

Measure/assess C- and A-weighted levels over sametime period. Correction to beapplied if the differencebetween the two levels is15 dB or more

5 dB2 C-weighting isdesigned to bemore responsive tolow-frequencynoise

Impulsivenoise

A-weighted fastresponse andimpulseresponse

If difference in A-weightedmaximum noise levels betweenfast response and impulseresponse is greater than 2 dB

Applydifference inmeasuredlevels as thecorrection, upto a maximumof 5 dB.

Characterised by ashort rise time of35 milliseconds(ms) and decaytime of 1.5 s

Intermittentnoise

Subjectivelyassessed

Level varies by more than 5 dB 5 dB Adjustment to beapplied for night-time only .

Duration Single-eventnoise durationmay range from1.5 min to 2.5 h

One event in any 24-hourperiod

0 to –20 dB(A) The acceptablenoise level may beincreased by anadjustmentdepending onduration of noise.(See Table 4.2)

Maximumadjustment

Refer toindividualmodifyingfactors

Where two or more modifyingfactors are indicated

Maximumcorrection of10 dB(A)2

(excludingdurationcorrection)

Notes:1. Corrections to be added to the measured or predicted levels.2. Where a source emits tonal and low-frequency noise, only one 5-dB correction should be applied if the tone is in the

low-frequency range.


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Table 4.2. Adjustments for duration

Duration of noise

(one event in any 24 hour period)

Increase in acceptable noise level at receptor, dB(A)

Daytime and evening

(0700–2200 h)

Night-time

(2200–0700 h)

1.0 to 2.5 hours 2 Nil

15 minutes to 1 hour 5 Nil

6 minutes to 15 minutes 7 2

1.5 minutes to 6 minutes 15 5

less than 1.5 minutes 20 10


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5 Meteorological conditions5.1 Introduction

Certain meteorological conditions may increasenoise levels by focusing sound-wave propagationpaths at a single point. Such refraction of soundwaves will occur during temperature inversions(atmospheric conditions where temperaturesincrease with height above ground level) and wherethere is a wind gradient (that is, wind velocitiesincreasing with height) with wind direction fromthe source to the receiver. These meteorologicaleffects typically increase noise levels by 5 to 10 dB,and have been known to increase noise levels by asmuch as 20 dB in extreme conditions, therebycausing a significant noise impact on residentsliving in areas prone to these effects.

Temperature inversions occurring within the lowest50 to 100 m of atmosphere can affect noise levelsmeasured on the ground. In the geographical areaswhere this policy applies, these temperature inver-sions are most commonly caused by radiativecooling of the ground at night leading to the coolingof the air in contact with the ground. This is espe-cially prevalent on cloudless nights with little wind.Air that is somewhat removed from contact with theground will not cool as much, resulting in warmerair aloft than nearer the ground.

In assessing noise impacts, the criteria are expectedto apply under weather conditions that would beexpected to occur at a particular site for a significantperiod of time. These include conditions of calm,wind and temperature inversions. As the criteria areexpected to apply under weather conditions charac-teristic of the area, it is important at the start of anoise assessment to assess the potential for suchmeteorological effects occurring, thus enablingbetter prediction of potential noise impacts. Thesections below outline the procedures for assessingtemperature inversions (Section 5.2) and wind effects(Section 5.3). Essentially, there are two underlyingapproaches to assessing these effects: the simpleand the more detailed approach.

Simple approach. With the simple approach, theproponent may forego detailed analyses of meteoro-logical data and simply apply given default mete-orological parameters to predict noise levels. Thisapproach assumes that meteorological effects are

present for a significant amount of time, avoidingthe need to quantify these effects in detail. It isconservative, in that it is likely to predict the upperrange of increases in noise levels. Actual noiselevels may be less than predicted. This approach isgenerally used to test whether further analyses arewarranted.

Detailed approach. The detailed approach involvesanalysing meteorological data to determine whetherinversion and/or wind effects are significantfeatures warranting assessment. Where assessmentis warranted, default parameters are available foruse in predicting noise or, where preferred, meas-ured values may be used instead. The detailedapproach gives a more accurate prediction of noiseincreases due to meteorological factors—as a trade-off for the additional work involved.

5.2 Temperature inversions

The 4-step procedure for assessing the amount bywhich noise is increased by inversion effects issummarised in Figure 5.1. Assessment of impacts isconfined to the night noise assessment period (10pm to 7 am), as this is the time likely to have thegreatest impact—that is, when temperature inver-sions usually occur and disturbance to sleep ispossible.

Essentially, the assessment involves a stagedapproach, designed to require an assessment onlywhere initial screening tests show that inversioneffects on noise are potentially significant. Wherethe potential is established, the next step is toanalyse existing meteorological data to determinethe percentage occurrence of temperature inver-sions. An occurrence of 30% of the total night-timeduring winter (June, July and August) has beenselected as representing a significant noise impactwarranting further assessment. As temperatureinversions generally occur during the night-timeand early morning periods, this percentage occur-rence corresponds to about two nights per week.The night-time period for determining inversionfrequency is from 1 hour before sunset to 1 hourafter sunrise (taken to be 6 pm to 7 am), which is thetime period during which inversions are most likely.(This is different from the night noise assessmentperiod over which inversions are to be assessed,


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Figure 5.1. Assessing temperature inversions

Step 1: Do initial screening test

Determines whether inversion effects need to be considered

Step 2: Determine % occurrence of inversions

Use existing data (Bureau of Meteorology) or on-sitemeasurements

STEP 4: Compare predicted level with project-specificnoise levels

The predicted noise levels due to the inversion conditionsare compared with the project-specific noise levels. Wherethey exceed the project-specific noise levels, noise impacts

are likely.

Is the occurrence ofinversions significant, i.e.> 30% of nights in winter?

NO

YES

No furtherassessment is

required

STEP 3: Decide on inversion parameters to use

Use either default inversion values specified by the policyor actual measured values

Are inversion effects likely tosignificantly affect noise

levels?

NO

YES


33

which is from 10 pm to 7 am.) Winter is selected asthe appropriate season in which to determinewhether temperature inversions are significant, as itrepresents the season with the highest frequency ofoccurrence of temperature inversions.

Default values for temperature inversions anddrainage-flow wind speed are provided for use inassessing impacts where inversions are present forat least 30% of the total night time during winter.Alternatively, actual inversion strength and windspeed values based on on-site measurements may beused instead of the default values.

A brief description of the main components of theprocedure for assessing noise increases due toinversion effects is presented below. Details of thefull procedure are presented in Appendix C.

Step 1: Do initial screening tests

To assess the level by which noise is increased as aresult of inversion effects, it is generally necessary toanalyse meteorological data from the area in ques-tion. However, before doing any detailed analyses,the potential for temperature inversions to increasenoise impact should be determined. Detailedanalyses of meteorological data are not requiredwhere there is little or no potential for impact, as inthe following cases:

• where the development in question does notoperate during the night-time hours. Astemperature inversions are usuallyprominent during night-time hours, there isno need to consider their effects for adevelopment that does not operate at night(10 pm to 7 am)

• where, by using the default values, (seeAppendix C Table C1 for screening test defaultvalues), it can be shown that there would beno significant additional noise impactsduring inversion conditions (for example,less than a 3-dB increase). In this situation,no further analysis of inversion effects isrequired. Situations where this could occurinclude:

—areas that experience only a slight increasein noise due to inversions

—areas where the most-affected premisesmay be located close to the development,thus negating the effects of inversions

(which focus noise at relatively largedistances).

Step 2: Determine the significance oftemperature inversions

Where screening tests (Step 1) indicate that inver-sions could have a significant impact on noise, theproponent may want to do further analyses toconfirm whether the occurrence of temperatureinversions at the locality is significant. This wouldinvolve determining the percentage occurrence ofmoderate and strong inversions during winter,based on existing meteorological data and usingany one of the methods outlined in Appendix E.(Weak inversions are not included, as they are notconsidered to have a significant impact on noise.)Where inversion conditions are predicted for atleast 30% (or approximately 2 nights per week) ofthe total night time in winter, then inversion effectsare considered to be significant and should be takeninto account in the noise assessment.

In NSW, the Hunter region has been identified as anarea often affected by temperature inversions. Forthis reason, the Hunter has been studied in detail,and the percentage occurrence of temperatureinversions has been determined for the entire regiondown to a 2-km grid-square resolution. (See Appen-dix F.)

Step 3: Decide on inversion parametersto use

There are two options: use the default parametersspecified, or use parameters determined by directmeasurement.

A. Using default inversion parameters

Default values for inversion strength and windspeed have been specified for use in the noiseassessment to avoid the need for potentially costlyon-site monitoring. These default values have beenchosen based on the analysis of available field data.Essentially, the following default parameters arespecified for non-arid and arid areas:

Non-arid areas (annual average rainfall greater than500 mm):

Moderate (F-class stability category) inversions

• 3 °C/100 m temperature inversion strengthfor all receivers, plus a 2 m/s source-to-


34

receiver component drainage-flow windspeed for those receivers where applicable.(See below for applicability of drainage-flowwind.) For more information see Appendix C.

Arid and semi-arid areas (annual average rainfall lessthan 500 mm):

Strong (G-class stability category) inversions

• 8°C/100 m temperature inversion strengthfor all receivers, plus a 1 m/s source-to-receiver component drainage-flow windspeeds for those receivers where applicable.(See below for applicability of drainage-flowwind.)

Applicability of drainage-flow wind

The drainage-flow wind default value shouldgenerally be applied where a development is at ahigher altitude than a residential receiver, with nointervening higher ground (for example, hills). Inthese cases, both the specified wind and tempera-ture inversion default values should be used in thenoise assessment for receivers at the lower altitude.

B. Using direct measurement

Where the proponent rejects the default values andwishes to use alternative values based on directmeasurement, use the procedure outlined in Appen-dix E.

(Note: Wind data should be collected at 10 mheight.)

Step 4: Assess the expected impact

The increased noise level predicted under inversionconditions is then compared with the project-specific noise levels to determine whether any noiseimpacts are expected. Noise impacts are likelywhere exceedances of the project-specific noiselevels are predicted.

5.3 Wind effects

The effects of gradient wind on noise levels alsoneed to be accounted for when assessing the impactfrom a planned development. Gradient wind differsfrom the drainage-flow wind associated withtemperature inversions:

• drainage-flow wind is the localised drainageof cold air under the influence of the localtopography, and travels in one direction only(direction of decreasing altitude)

• gradient wind is the regional winddetermined by synoptic factors (high andlow-pressure systems), and may originatefrom any direction.

Wind data are usually relatively easy to obtain, andwind roses are commonly used in most environ-mental impact assessments. Unlike temperatureinversions, gradient winds may cause impactsduring any assessment period (day, evening,night)—not just the night period. Hence the assess-ment of these effects should consider all assessmentperiods.

5.3.1 When do wind effects need to beassessed?

Wind effects need to be assessed where wind is afeature of the area. Wind is considered to be afeature where source-to-receiver wind speeds (at 10-m height) of 3 m/s or below occur for 30 per cent ofthe time or more in any assessment period (day,evening, night) in any season. This differs from theprocedure used with temperature inversions, in thatthe 30-per-cent occurrence applies to all seasonsand each assessment period—and not just thewinter season and night assessment period. Thereare two ways to assess wind effects:

• Use a wind rose to determine whether windis a feature based on the frequency ofoccurrence and wind speed. In doing this,take care to assess the source-to-receivercomponents of wind that are relevant.

• Simply assume that wind is a feature of thearea (foregoing the need to use a wind rose)and apply a ‘maximum impact’ scenario.

5.3.2 What wind speed should be usedwhen assessing noise impacts?

Wind is considered in two ways; the wind near theground at the microphone position, and the windaloft at 10 m above the ground.

When wind near the ground increases its speed itcan increase ambient noise levels by rustling foliageand creating turbulence when passing over or


35

around structures. At higher wind speeds, the noiseproduced by wind will drown out noise from mostindustrial and transportation sources. Wind canalso create extraneous noise on noise-monitoringequipment; an upper limit of 5 m/s at the micro-phone position is commonly applied during noisemeasurement to reduce this effect.

Where wind speeds increase with height there is aneffect that is analogous to temperature inversionsbut restricted to localities downwind of the noisesource. This effect is represented by the wind speedand direction measured at a 10 m height above theground. The 10-m wind may either be a drainageflow wind associated with an inversion or a gradi-ent wind. The link between the near ground windand the 10-m wind has been described as a powerlaw relationship. This relationship can be complexand can depend on site factors such as the surfaceroughness and the stability of the atmosphere. Thismeans that the 10-m wind cannot, as a general rule,be accurately derived from wind velocity measure-ments near the ground and vice versa.

In summary:

• Noise can be increased by wind.

• Wind can create high ambient noise levels.

• Wind can create extraneous noise on noise-monitoring equipment.

• The near-surface wind and the 10-m windcan cause different noise effects, so that bothneed to be assessed.

• The near-surface wind relates to effects on thenoise monitoring equipment and noisegenerated through mechanical interactionwith trees and other obstructions, whereasthe 10-m wind relates to sound-waverefraction through the atmosphere, similar toinversions and its consequent effects on noiselevels.

• A significant wind effect near the ground atmicrophone height does not necessarily meanthat a significant wind effect will occur at10 m (and vice versa).

A default wind speed of 3 m/s (at 10-m height) isproposed for assessing noise impacts caused bygradient winds. This wind speed can noticeablyincrease noise received down-wind of a noise

source, but may not increase ambient noise levels tothe point where they mask noise from the sourceand make it unnoticeable. A 10-m wind of 3m/s isalso unlikely to be associated with near-surfacewinds of a strength able to cause increased ambientnoise levels that would mask increased levels ofnoise from the source.

Where there is 30 per cent or more occurrence ofwind speeds below 3 m/s (source-to-receivercomponent), then use the highest wind speed(below 3 m/s) instead of the default.

Where there is less than a 30 per cent occurrence ofwind of up to 3 m/s (source-to-receiver component),wind is not included in the noise-prediction calcu-lation.


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6 Predicting noise levels & determiningimpacts

An important aspect of noise assessment—afterdetermining the project-specific noise levels—is theprediction of noise levels from an industrial noisesource, leading to the determination of noise impact.

This process involves:

1. Identifying all possible source, site andreceiver parameters so that noise can beadequately predicted.

2. Predicting noise levels from the source atreceiver locations—taking into account allimportant parameters identified, as well asthe project-specific noise levels.

3. Comparing the predicted noise level with theproject-specific noise levels to determine thenoise impact.

6.1 Identifying noise parameters

The important parameters for predicting noise arelisted below. These will set the boundaries of thenoise prediction process. They need to be deter-mined and clearly identified for noise impacts to bepredicted adequately:

• all noise sources related to the proposeddevelopment, including vehicles that operateon site

• source noise levels, site location and effectiveheight of the noise source. References shouldbe provided for all source noise levels used inthe assessment (for example, directmeasurement, previous EIS, manufacturer’sspecifications)

• all stages of project development

• all nearby receivers potentially affected by thedevelopment

• weather conditions applicable to the site(from Section 5); noise criteria apply underexisting weather conditions

• site features (including natural andconstructed, development and surrounding

land uses) that affect noise propagation

• operating times of the development.

6.2 Noise prediction

To quantify the noise impact, the noise levels fromthe source at all potentially affected receiversshould be predicted, taking account of the param-eters identified (Section 6.1).

The noise levels predicted should correspond to thenoise descriptor of the project-specific noise levelsapplicable to the project. For example, the noiselevels should be predicted in terms of:

• LAeq,period if the amenity criteria establish theproject-specific noise levels

• LAeq,15 minute if the intrusive criterionestablishes the project-specific noise levels.

Any assumptions made when determiningdescriptors should be clearly validated and re-ported in the assessment.

For small or simple projects, the predicted noiselevel from the source may be calculated manually,taking into account the distance from the source toreceiver and any shielding between the source andreceiver.

For large or difficult projects, noise is generallypredicted through the use of computer noise mod-els. Such models generally take account of noiseattenuation due to distance, atmospheric absorp-tion, barriers, effects of intervening ground typesand weather conditions. They use informationabout source noise levels, location of sources,topography between source and receiver andweather conditions to calculate overall noise levelsat a receiver location. Strong preference will begiven for the use of modelling approaches that havebeen the subject of peer review and that form ac-cepted practice (for example, Environmental NoiseModel (ENM) or Soundplan). Any other modellingapproaches used would need to be validated before


37

being used for a particular project. Where largenumbers of people are likely to be affected by noise,a map showing predicted noise levels as noisecontours surrounding the development is required.

6.3 Determining impacts

The noise impact of the development can be deter-mined by comparing the predicted noise level at thereceiver with the project-specific noise levels thathave been derived for that particular location. Thedevelopment is considered to cause a noise impact ifthe predicted noise level at the receiver exceeds theproject-specific noise levels for the project. Theextent of noise impact from the development isdefined by the extent the predicted noise levelexceeds the project-specific noise levels and thenumber of receivers affected.

6.3.1 Impacts under adverse weatherconditions

As described in Section 5, adverse meteorologicalconditions such as temperature inversions andwinds can act to increase the level of noise receivedfrom a noise source. These meteorological effectsmay also result in increased levels of ambient noisecontributed by industry and background noise.Wind can also reduce noise levels at the receiverwhere it blows from the receiver towards the indus-try.

These effects are site specific and often complex anddifficult to quantify. Extended monitoring and/ordetailed modelling may be needed to capture theeffects or predict what is expected to occur. Thecomplexity and expense involved in quantifying theeffect of adverse meteorological conditions onbackground noise levels or ambient noise levelscontributed by industry preclude these detailedprocedures from being a requirement in assessingnoise impact. However, it is recognised that sucheffects do occur, and these procedures may be usedto assess the effects of meteorological conditions onbackground noise levels and ambient noise levels inthe noise assessment report.

The over-riding objective is to ‘compare like withlike’ and to ensure that the situations where themaximum level of impact is likely to occur areidentified and quantified. For example, where theimpact from a proposed development is to be

assessed under adverse wind conditions (forexample, a 3 m/s wind blowing from source toreceiver), then where a background noise level canbe quantified for those same conditions it is reason-able that this background noise level should beused to assess impacts under these conditions.

In all cases the rating background level should bedetermined (as per Section 3.1) as the starting point,and any adjustments for adverse meteorologicalconditions can then be applied to this base value.Impact should be assessed under both adverse andnon-adverse meteorological conditions to determinethe maximum impact that may occur.

Quantifying the influence of temperature inversionson background noise levels can be done in a similarfashion, and the policy provides a number ofmethods for estimating the presence of temperatureinversions.

The influence of adverse meteorology on the indus-try contribution to ambient LAeq noise levels may bemore difficult to establish. However, where this canbe quantified with a reasonable level of confidencethe resultant noise levels may be used in assessingimpact against the criteria.

It is emphasised that sufficient objective evidencemust be supplied to support any claim for increasedbackground noise levels or industry contribution tothe ambient LAeq levels. It is not sufficient to relysolely on past experience; a site-specific analysis ofthe effects of meteorology must be undertaken.


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7 Mitigating noise from industrial sources

A set of generic mitigation measures that may applyto industrial development in general, plus addi-tional measures for specific types of development,are set out in Section 7.7.

7.2 Controlling noise at the source

Best management practice

Best management practice (BMP) is the adoption ofparticular operational procedures that minimisenoise while retaining productive efficiency.

When an appropriate mitigation strategy thatincorporates expensive engineering solutions isbeing considered, the extent to which cheaper, non-engineering-oriented BMP can contribute to therequired reduction of noise should be taken intoaccount.

Application of BMP includes the following types ofpractice:

• in open-cut mines: restricting movement oftrucks on ridgelines and exposed haul routeswhere their noise can propagate over a widearea, especially at night. This meansrestricting night-time movement of spoil toareas shielded by barriers or mounds, andreserving large-scale spoil movement fordaytime

• scheduling the use of noisy equipment at theleast-sensitive time of day

• siting noisy equipment behind structures thatact as barriers, or at the greatest distance fromthe noise-sensitive area; or orienting theequipment so that noise emissions aredirected away from any sensitive areas, toachieve the maximum attenuation of noise

• where there are several noisy pieces ofequipment, scheduling operations so they areused separately rather than concurrently

• keeping equipment well maintained

7.1 Introduction

The processes described in Sections 2 to 6 establishthe project-specific noise levels and the predictednoise levels from the source. When the predictednoise level from the noise source exceeds the project-specific noise levels, mitigation measures that willreduce noise levels to meet the project-specific noiselevels need to be considered. The degree of noiseimpact quantifies the extent of mitigation required,and points to an appropriate mix of noise controlmeasures to be adopted as a mitigation strategy.

This policy focuses on achieving the desired envi-ronmental outcomes—there is no prescribed man-agement or mitigation strategy to achieve theproject-specific noise levels. In this way, the noise-source manager is given maximum flexibility incontrolling noise.

The sections below provide guidance on whatmitigation and management measures might beappropriate for particular types of developmentassociated with specific noise problems.

Essentially, there are three main mitigation strate-gies for noise control:

1. Controlling noise at the source.

There are two approaches: Best ManagementPractice (BMP) and Best Available Technol-ogy Economically Achievable (BATEA). Theseare described in Section 7.2.

2. Controlling the transmission of noise.

There are two approaches: the use of barriersand land-use controls—which attenuatenoise by increasing the distance betweensource and receiver. These are detailed inSection 7.3.

3. Controlling noise at the receiver.

These measures are detailed in Section 7.4.

The overall approach to assessing appropriatestrategies is outlined in Section 7.5.

The management of short-term exceedances forwhich mitigation is impractical is discussed inSection 7.6.


39

• employing ‘quiet’ practices when operatingequipment—for example, positioning idlingtrucks in appropriate areas

• running staff-education programs on theeffects of noise and the use of quiet workpractices.

Best available technology economicallyachievable (BATEA)

Allied with BMP is ‘best available technologyeconomically achievable’ (BATEA). With BATEA,equipment, plant and machinery that produce noiseincorporate the most advanced and affordabletechnology to minimise noise output. Affordabilityis not necessarily determined by the price of thetechnology alone. Increased productivity may alsoresult from using more advanced equipment,offsetting the initial outlay—for example, ‘quieter’equipment that can be operated over extendedhours. Often old or badly designed equipment canbe a major source of noise.

Where BMP fails to achieve the required noisereduction by itself, the BATEA approach shouldthen be considered. Most of the noise-controlmeasures listed in Section 7.7 belong to this ap-proach. Examples of uses of BATEA are:

• adjusting reversing alarms on heavyequipment to make them ‘smarter’, bylimiting acoustic range to the immediatedanger area

• using equipment with efficient muffler design

• using quieter engines, such as electric insteadof internal combustion

• using efficient enclosures for noise sources

• using vibratory piling in place of impactpiling

• using high-pressure hydraulic systems tosplit rock, instead of hydraulic or pneumatichammers

• damping or lining metal trays or bins

• active noise control.

7.3 Controlling noise in transmission

Barriers

Barriers are more effective if they are near the sourceor the receiver. Their effectiveness is also determinedby their height, the materials used (absorptive orreflective), and their density. The relationship ofthese design features to attenuation is well docu-mented.

Barriers can take a number of forms—includingfree-standing walls along roads, grass or earthmounds or bunds, and trenches or cuttings withinwhich noise sources are sited. They are employedwhen source and receiver control is either impracti-cal or too costly.

Land-use planning—a strategic approachto noise mitigation

Strategic issues related to integrating transport andland-use are dealt with in detail in the Environmen-tal Criteria for Road Traffic Noise (EPA 1999).

Noise impacts from industry in residential andother noise-sensitive areas stem mostly from inap-propriate land-use decisions that allow industry todevelop close to these areas. Once land is developedin this way, the range of available noise-controlmeasures is restricted to better management of theindustrial site, and engineering solutions. One ofthe most costly controls considered at this late stage,the acquisition of residences, creates a noise buffer-zone of land. These conflicts could have beenavoided had appropriate land-use decisions beenmade at the initial stage of land-use planning.

While judicious use of land use planning tech-niques may often avoid noise becoming an issue itis not intended that they should be relied on as theonly mitigation strategy. Noise generators areresponsible for applying all feasible and reasonablenoise mitigation controls at the noise source. Thismaximises the amount of land unaffected by noise.

Where land-use planning can be applied as a noisecontrol tool (generally in newly developed areas),this is preferred to waiting until a specific noiseimpact is identified before seeking noise controlmeasures.

Land-use planning can be used as a noise controlmeasure at three development stages:


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1. The initial planning stage.

A greenfield (undeveloped) site offers thegreatest management flexibility to zoneindustrial and noise-sensitive land. This isthe point where compatibility of differentland uses should be considered. In certaininstances where land is not at a premium,buffer zones that use land for recreational orbusiness purposes may be an option.

2. The residential subdivision planning stage.

When a commitment has already been givento locating residential and industrial landareas close to one another, but residentialdevelopment has not started, there is anopportunity to develop internal subdivisiondesigns that allocate the least noise-sensitiveland uses (for example, shopping centres,parks, sporting complexes) nearest to indus-try. It follows that the most sensitive landuses (for example, residential, places ofworship) would then be located furthestaway from industry.

3. The house-design stage.

If subdivision development has commencedin a potential noise-impact area, and there isno opportunity for flexibility in planningland use, controls on house design—toachieve the greatest level of external tointernal noise attenuation—can still beconsidered. This would include locatingliving areas of the house away from the faceexposed to noise, allowing the rest of thehouse to act as a barrier for it.

Extractive industry by its nature has no locationalflexibility. In this case, appropriate strategic land-use planning from a noise perspective could incor-porate allowances for the fixed industrial site inlocating noise-sensitive land uses and associatedbuffer zones. To be effective, planning would needto anticipate future extractive-industry land require-ments—which implies knowledge of the location ofmineable ore bodies—so residential developmentcan be isolated from these areas wherever possible.

7.4 Controlling noise at the receiver

Noise controls at the receiver are expensive whenmany receivers require treatment, but may beattractive and cost-effective where only a fewreceivers would be affected by noise and the alterna-

tives are even more expensive source controls. Cost-effectiveness is also determined by the increase infuture potential receivers where residential land isbeing developed near the noise source.

The two major controls are insulation and double-glazing of windows. For these to be effective, theresidence needs air conditioning, or a sophisticatedventilation system that does not compromise theeffect of the noise insulation.

The most extreme control is property acquisition.

7.5 Noise mitigation strategies

Selecting an appropriate strategy for a proposeddevelopment or alterations to an existing develop-ment involves the following steps:

1. Determining the noise reduction required toachieve the project-specific noise levels.

2. Identifying the specific characteristics of theindustry and the site that would indicate apreference for specified measures.

3. Examining the mitigation strategy chosen bysimilar industries on similar sites withsimilar requirements for noise reduction; andconsidering that strategy’s appropriatenessfor the subject development.

4. Considering the range of noise-controlmeasures available (as suggested in thischapter).

5. Considering community preferences forparticular strategies. This is especiallyimportant when the community has particu-lar sensitivities to noise.

The preference ranking (from most preferred to leastpreferred) for particular strategies is:

1. Land-use controls—a long-term strategypreferable to other measures when suchstrategic decisions are possible in planningland use, as it separates noise-producingindustries from sensitive areas and avoidsmore expensive short-term measures.

2. Control at the source—BMP and BATEA—used in conjunction, these strategies are thebest after land-use planning, as they serve toreduce the noise output of the source so thatthe surrounding environment is protectedagainst noise.


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3. Control in transmission—the next beststrategy to controlling noise at the source—itserves to reduce the noise level at the receiverbut not necessarily the environment sur-rounding the source.

4. Receiver controls—the least-preferredoption, as it protects only the internal envi-ronment of the receiver and not the externalnoise environment.

Proponents will take into account the cost-effective-ness of strategies in determining how much noisereduction is affordable. A proponent’s choice of aparticular strategy is likely to have unique featuresdue to the economics of the industry and site-specific technical considerations.

The above steps and the range of measures de-scribed in the chapter can be used as a guide inassessing the strength of the proponent’s mitigationproposals.

Where a proposed mitigation strategy will notachieve the desired noise reduction and leaves aremaining noise impact, the problem needs to besolved by negotiation. The negotiation process is thesubject of Section 8.

7.6 Managing short-term exceedanceof approved noise levels

From time to time, managing noise at the source mayrequire a short-term increase in noise beyond thelevel approved. Such situations may include:

• running-in new equipment

• abnormal operations due to unforeseenbreakdown or maintenance requirements

• occasional needs to move heavy equipment tonew locations on site.

Mitigation strategies are often impractical for suchshort-term events.

The noise-source manager should demonstrate thatall alternatives to noisier operations have beenconsidered before seeking an accommodation fromthe relevant regulatory/consent authority to operatein excess of the agreed noise levels. If it is judgedthat such an accommodation for a short-term noisieroperation is warranted, the following options couldbe considered:

• confining noisier operations to the least-noise-sensitive part of the day—which wouldbe when the background noise is highest

• determining an upper level for noise impact

• consulting with the community regarding theproposed events.

7.7 Generic noise control measures

Typical noise sources on industrial sites include:

• engines

• exhausts

• fans

• transport of materials, such as on conveyorsand trucks

• milling and stamping (metal works)

• sawing and debarking (wood mills)

• processors such as crushing and separating

• pumps and compressors

• whistles and alarms

• material dumping and scraping

• electrical transformers and switchingequipment.

The choice of noise control measures depends onboth the degree of mitigation required and theundesirable characteristics of the noise source thatneed to be controlled. The actual measures chosenwill also depend on site factors, such as the abilityof the site to accommodate particular engineeringmeasures relative to other measures and their sitecosts.

A generic set of noise-control measures is set outbelow, with additional measures shown thatrespond to particular developments.

Generic list of mitigation measures

Noise-source controls

• enclosing the source—the design of theenclosure and materials used to absorbsound will affect the attenuation achieved


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• silencing exhausts—muffler design andnoise barrier systems

• active noise control, effective on a limitedrange of noise sources

• times of operation.

Controls along the sound-transmission path

• noise barriers—more effective if near sourceor receiver; effectiveness also controlled bymaterials used (reflective or absorptive) andby height

• mounds, bunds and trenches

• site design to maximise the distance from thecritical noise source to the receiver, and withintervening buildings to act as barriers.

Controls at noise receiver

• insulation

• double-glazing of windows and use of airconditioning

• acquisition.

Additional mitigation measures forextractive industries

On-site transport of materials

• selecting vehicles with minimum noiseoutput—including tyre noise, exhaust andcompressor/fan noise

• using rolling stock with quiet couplings andbrakes

• using locomotives with components that donot emit tonal or low-frequency noise

• using trenches, cuttings, tunnels and barriersfor transport routes

• restricting times for truck operations onridgelines and in locations that are line-of-sight with receivers

• giving preference to haul routes with lowgrades

• using conveyor systems with low noiseoutput, paying particular attention to rollers

• enclosing conveyors where necessary

• maintaining plant and equipment to ensurethat the designers’ noise-outputspecifications continue to be met

• using ‘smart’ reversing alarms.

Mine and quarry operation

• locating materials-processing in the leastnoise-sensitive area, or enclosing it ifnecessary

• dumping spoil and waste behind barriers.

Additional mitigation measures for siteswith specific noise characteristics

Piling

• using piling shrouds or vibratory pilinginstead of impact piling to control impulsivenoise.

Milling and metal works

• using efficient enclosures, where needed, toreduce the impact of impulsive noise frommetal stamping

• reducing the impact or output of tonal noisefrom cutting equipment and saws, by usingenclosures or through equipment redesign.

Pumps, transformers and machinery producinglow-frequency or tonal noise

• where low-frequency noise is difficult toisolate, seeking specialist advice aboutmachinery redesign and restricted operatingtimes

• reducing tonal noise through machineryredesign, enclosure, or restricted operatingtimes; or by applying active noise control.

Sites producing intermittent noise during night-time operations

• Control may be specific to the way the noisesource is designed or how it fits in to theoverall industrial process. Using barriers,enclosing or redesigning the source, orchanging the operation to provide for a morecontinuous output are possible measures.


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8 Negotiation processWhere it can be demonstrated by the proponent thatthe development offers net benefits, a regulatory/consent authority may consider these as groundsfor applying the achievable noise levels, rather thanthe project-specific noise levels, as the statutorycompliance limit.

Negotiation on what represents the best achievablelevel that is practicable for a development is oftenan iterative process involving both the proponentand regulator/consent authority and the proponentand affected community. Where the proponent isseeking to demonstrate to the regulator/consentauthority that all feasible and reasonable noisemitigation measures have been applied, the propo-nent should include the results of their discussionswith the affected community in the package ofproposed noise mitigation measures. Beyond thispoint, the proponent might want to initiate addi-tional community-based negotiation where there ispotential for trade-offs attractive to the affectedcommunity. Typically, where the amenity criteria setthe project-specific noise levels for a project, negotia-tions between the proponent and the regulatorwould occur when site noise levels are between theacceptable and recommended maximum LAeq levelspresented in Table 2.1.

The section below outlines a checklist that can beused as a guide by EPA officers to determine anacceptable level of residual noise impacts whensetting statutory noise conditions, based on theconsideration of social and economic costs andbenefits.

8.2.1 Residual level of impact: checklist

It is important that, as far as possible, the noiseassessment quantifies any remaining or residualimpacts that exceed the project-specific noise levels,after applying feasible and reasonable mitigationstrategies.

The acceptability of the residual noise impactsshould be evaluated by taking into considerationfactors such as:

1. Characteristics of the area and receiverslikely to be affected, for example:

8.1 The process leading to negotiation

This chapter deals with that part of the overallprocess shown in Figure 1.1 in the box under theheading ‘Decision-making process’.

Any unacceptable impacts from a developmentproposal that are likely to persist after noise-mitiga-tion action has been taken can be dealt with throughnegotiation—either by improved mitigation or bytrade-offs with benefits.

Negotiation can be:

• between the proponent and the regulator—the traditional approach

• between the proponent and the affectedcommunity (which is in the best position forevaluating the trade-offs).

In the latter case negotiation is designed to beavailable to those people whose amenity is poten-tially affected by non-achievement of the project-specific noise levels. This type of negotiation proc-ess, which leads to the determination of an achiev-able noise limit, is in addition to the type of directconsultation that typically occurs between theproponent and the community throughout theimpact assessment process in defining the impor-tant project parameters.

8.2 Negotiation between proponentand regulator

Where proposed mitigation measures will notreduce noise levels to the project-specific noiselevels, the proponent should seek to negotiate withthe regulatory/consent authority to demonstratethat all feasible and reasonable mitigation measureshave been applied. The regulatory/consent author-ity can choose to accept the level of impact pro-posed, or negotiate for a better level of control wherethis is considered achievable.

Where, in the final analysis, the level of impactwould still exceed the project-specific noise levels,the economic and social benefits flowing from theproposed development to the community should beevaluated against the undesirable noise impacts.


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—the extent of the areas (including existing,developing or proposed residential, healthor education sites) and number of receivers(including groups that may be especiallysensitive to noise, such as pre-schoolers,students, the aged, hospital and nursinghome patients) likely to be affected by noiselevels above the project-specific noiselevels

—the daily activities of the community (inparticular, effects such as sleep distur-bance, speech interference, level of annoy-ance or effects on physical or physiologicalhealth)

—property values

—zoning of land uses affected by noise andthe appropriateness of the zoning or landuse

—the potential change in the ambient noiselevels as a result of the proposal; cumula-tive noise impacts in the area; and whetherparts of the area that are already moder-ately or badly affected by noise will bemore or less affected

—the extent to which biodiversity (especiallynative birds and other animals) will beaffected

—the likely variation between individuals inresponse to the noise

—the amenity of areas used for outdoorrecreational activities or conservation,heritage or wilderness areas

—other industry in the area (includingagriculture).

2. Characteristics of the proposal and its noiseor vibrations, such as:

—the noise characteristics of the activity

—the extent to which any remaining noiseimpact exceeds the project-specific noiselevels

—the circumstances and times when theproject-specific noise levels are likely to beexceeded

—the circumstances and times when thesource noise levels are likely to be belowthe project-specific noise levels (for exam-ple, when wind blows source noise awayfrom the receiver)

—the accuracy with which impacts can bepredicted, and the likelihood that theimpacts will occur in the manner predicted

—the degree to which the character of thenoise is new to an area and differs fromexisting noise sources

—the economic benefit and social worth ofthe proposal for the local area, the regionor the nation.

3. The feasibility of additional mitigation ormanagement measures:

—alternative sites or routes for the develop-ment

—the technical and economic feasibility ofalternative noise controls or managementprocedures.

4. Equity issues in relation to:

—the costs borne by a few for the benefit ofothers

—the long-term cumulative increase in noiselevels

—the opportunity to compensate effectivelythose affected.

8.3 Negotiated agreements betweenthe proponent and the affectedcommunity

An alternative mechanism that could be applied isthe more inclusive approach of a negotiated agree-ment between the affected community and theproponent, with traditional regulatory/consentauthorities playing a supporting role. Negotiation isdesigned to be available to those people whoseamenity is potentially affected by non-achievementof the project-specific noise levels. While negotiationon agreed noise levels between the proponent andthe community can occur at any time, this shouldoccur when site noise levels exceed the recom-mended maximum LAeq levels presented in Table 2.1.

The affected community is in the best position toknow how much noise it is prepared to bear for apackage of benefits that would flow from the opera-tion of the facility creating the noise. As this ap-proach is new, a model for the process has not beenestablished. The process could be initiated when theproponent has demonstrated that the project-specific noise levels could not be met.


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Features of a negotiated agreementprocess

How the process might be initiated

The process might be initiated when:

• the regulatory/consent authority is satisfiedthat no further reduction in noise levels canbe made through a viable mitigation strategythat would seek to achieve the project-specificnoise levels; and

• the proponent demonstrates that—even whenusing the best of their economically viablestrategies—the project-specific noise levelscannot be achieved.

Who participates

The principal parties would be the proponent andthe affected community, with regulatory authoritiesand the council participating in an advisory capac-ity.

There is a need to define the ‘affected community’:this could comprise occupiers of residences and ofother noise-sensitive land uses identified as beingpotentially affected.

The proponent would need to employ an effectivemeans (for example, advertising) of reaching allpeople who are potentially affected. Advice mayinclude how individuals could register as ‘inter-ested and affected parties’ and become participantsin the negotiation process.

What is negotiated

The principal trade-off would probably be addi-tional noise impact in return for a package ofbenefits. Additional noise could be defined in termsof extended times of operation, higher noise levels,and a defined time period for annoying noisecharacteristics to operate and for more noise tooccur in the less sensitive parts of the day. Benefitscould include less noise at sensitive times, treatmentof residences, contributions to improve communityfacilities and infrastructure or acquisition of resi-dences. The NSW Industrial Noise Policy could act asa framework for negotiations regarding a set ofacceptable noise conditions.

The impact-assessment process may identify areasof noise-source management where concessions are

practicable. The proponent may not be able toreduce noise further. In these circumstances, otherbenefits might be negotiated unrelated to bettermanagement of the noise source but related tomaterial benefits for the community.

It is important for the negotiating community tounderstand the implications of its negotiationsregarding the additional noise impacts. Either theproponent or an independent specialist shouldpresent an analysis of the impacts from the optionsbeing canvassed, in such a way that the lay commu-nity can appreciate the likely implications of theirnegotiations.

The community would need to be well informed, tosafeguard against a position being reached wherethe agreed noise level represents an unreasonableimpact that, ultimately, is likely to be regretted bythat community.

How agreement might be negotiated

Representatives of the community could have equalstatus in the negotiating process with the propo-nent, and with any other parties (such as the EPA,councils and DUAP) acting in an advisory capacity.

Meetings could be chaired by an independentfacilitator and, depending on the circumstances, thecosts of the process may be borne solely by theproponent or may be shared equitably between theproponent and the community.

How agreement could be reached

‘Agreement’ would need to be defined for thecommunity so that a single community view couldbe regarded as representative. This could mean anumber of things—including a simple majority voteby the ‘affected community’, or a majority vote at ameeting held to reach an agreement; ‘majority’could be defined to extend to a higher than 51 percent level (for example, 60 per cent or 80 per cent).The many options would need to be evaluated. Thecommunity should determine for itself its preferredmethod for indicating its views when negotiating itsposition.

Treatment of ‘affected’ community members whodo not support the agreement

Proponents could propose a package of assistanceto be considered by these community members.


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How future affected landowners would be treated

The council may act on behalf of future owners ofthese properties. The existence of an agreementaffecting such land may be in the form of informa-tion provided on Section 149 Certificates routinelyobtained by purchasers of properties.

The effect on property values of any agreement mayin itself be part of the negotiations.

How the agreement could be enforced

The agreement would need to be enforced to theextent that it imposed obligations on the proponent.This could be achieved by making these obligationseither development consent conditions or licenceconditions. The obligations would need to beexpressed clearly and unambiguously. The condi-tions may also need to specify a way of measuringclearly whether the proponent has fulfilled theseobligations.

Further, the conditions must be reasonable from thepoint of view of existing and future landowners.

Mediation

An integral part of the process may need to be amediation and dispute resolution process, as thereis the potential for contentious issues to be raised.

Review

The consent or licence conditions could also pro-vide for a review after a certain period. The condi-tions could then set out the method of review andthe fact that the licence conditions may be changedas a result of that review.

The conditions could provide for the review periodto be shortened where the original conditionsforming the basis for negotiations had changed.Any review period should be of sufficient durationto give certainty to the proponent for the operationof the facility.


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9 Consent/licence conditions

The process by which a consent authority grantsdevelopment consent or regulatory authority issueslicences with associated conditions is set out inFigure 1.1. Only where a noise impact is identifiedwould a mitigation strategy need to be considered.Negotiation would be needed only when the propo-nent considered that the project-specific noise levelswere not achievable.

9.1 What is included in the consent/licence

A consent agreement or licence condition arrived atthrough the process described in this policy willhave taken the following issues into account:

• the assessed noise impact, which includes theimpact of the noise source and any additionalimpact caused by meteorological conditions

• mitigation measures required to achieve theproject-specific noise levels

• identification of a practical limit on noisecontrol

• consideration of trade-offs

• whether the final noise level proposed isacceptable.

It is important to note that the agreed limits in theconsent or licence apply under the meteorologicalconditions determined by the policy to be relevant tothe assessment site.

Complaints about subsequent operation of thefacility may arise where the project-specific noiselevels are achieved, or when a higher level is negoti-ated, because it is not possible to protect the wholerange of individual sensitivities to noise.

Complaints are also possible during extreme tem-perature inversions that were not covered in theassessment process because of their infrequency (seeSection 9.2).

9.2 Specifying meteorologicalconditions in the consent/licence

The meteorological effect by its nature is variable.Particularly intense inversions may occur, leadingto actual noise increases greater than those assessedin the policy. This is because the policy’s approachis to identify levels of noise increase that occur for asignificant period of time—approximately twonights a week during winter. Other, more intenseevents may occur for a shorter period of time. Thisshorter period is judged in the policy as not beingsignificant and, therefore, not warranting theadditional expense and difficulty of either a higherlevel of mitigation or consideration of alternativestrategies to meet the greater impact.

This approach is similar in philosophy to that usedwith transportation noise, where an appropriateamenity level is set to protect 90 per cent of theexposed population from being ‘seriously affected’.It is not practicable to protect the whole population,because the response to noise varies widely betweenindividuals. In the case of noise increased bymeteorological effects, the noise limit may allowsome undesirable impacts on a proportion of thepopulation during the short term and duringunrepresentative meteorological events that in-crease noise to an excessive degree. As is the casewith transportation noise, it is not practicable tomeet the noise limit under all inversion events,hence exceedances under extreme temperatureinversions are not considered to be a non-compli-ance with consent or licence conditions.

To ensure that the consent or licence conditionapplies under typical meteorological conditionsrelevant to the site (that is, the condition determinedfrom Section 5) a consent or licence condition may bebased on the following:

• For developments where F-class inversions(normally associated with non-arid areassuch as the Hunter Valley and coastal areas)were found to be a feature of the area (that is,using the procedure outlined in Section 5.2)the following statement could accompany thenoise limits in the condition:


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‘The noise limits apply under all meteorologicalconditions except

—during rain and wind speeds greater than3 m/s; and

—from 6 pm to 7 am during intense inversions,which are indicated by cloud cover less than 40per cent and wind speeds less than 1.0 m/s.’

Note: Wind data should be collected at 10 mheight.

The latter point above excludes non-stand-ard inversions (which are intense inver-sions—G-class inversions in this case), andis based on parameters specified in theTurner methodology for determining tem-perature inversions (described in Appendix E).

• For developments where G-class inversions(normally associated with arid areas such asBroken Hill and other flat inland areas) werefound to be a feature of the area (using theprocedure outlined in Section 5.2) thefollowing statement could accompany thenoise limits in the condition:

‘The noise limits apply under all meteorologicalconditions except during rain and wind speedsgreater than 3 m/s.

Note: Wind data should be collected at 10 mheight.

G-class represents the upper limit of inver-sion conditions, and no more extreme condi-tions are expected to occur.


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10 Applying the policy to existingindustrial premises

This section establishes a noise reduction programfor existing industrial noise sources, based on anagreed process for assessing and managing noise.This approach is designed to allow establishedindustries to adapt to changes in the noise expecta-tions of the community while remaining economi-cally viable.

The need to establish achievable noise limits andimplement a noise reduction program may betriggered by actions such as:

• the site becomes the subject of serious andpersistent noise complaints

• a proposal to upgrade or expand the site

• the site has no formal consent or licenceconditions and management wish to clarifytheir position

• management chooses to initiate a noisereduction program.

This approach provides a formal structured pro-gram to reduce high existing noise levels to accept-able levels over time by applying feasible andreasonable control measures. It establishes certaintythrough an agreed process to achieve noise reduc-tion, while providing flexibility in the choice ofnoise reduction measures.

10.1 Applying the policy to existingsites

Many existing industrial sources were designed forhigher noise emission levels than the criteria out-lined in this policy. In other cases industries mayhave been in existence before neighbouring noise-sensitive developments and even before noise-control legislation was introduced. The range ofmitigation measures available for these sites may beeither extremely limited or costly.

Applications for extensions to existing premisesoften provide an opportunity to redress issues thatrelate to the whole site. The need for reduced noisefrom existing sites must be weighed against the

wider economic, social and environmental consid-erations. Where noise emissions from the site exceedthe project-specific noise levels, the regulatoryauthorities and the noise-source manager need tonegotiate achievable noise limits for the site. Theproject-specific noise levels should not be appliedas mandatory noise limits. The project-specific noiselevels supply the initial target levels and drive theprocess of assessing all feasible and reasonablecontrol measures. Achievable noise limits resultfrom applying all feasible and reasonable noisecontrol measures. For sites with limited mitigationmeasures the achievable noise limits may some-times be above the project-specific noise levels.

In many instances the site will be required to reduceits noise emissions progressively to achieve thespecified noise limits by specified dates. This willrequire noise to be managed as an integral part ofsite upgrades. However, the development of formaloperating practices to reduce noise generation oftenneed not be linked to site upgrades, and wherefeasible these operating practices should be appliedat the earliest opportunity. The measures required toachieve the noise limits would usually be set out ina noise reduction program, with mitigation meas-ures staged over time. The noise reduction programwould typically be attached as a licence condition.Efforts should be aimed at achieving a reduction innoise in a manner that provides the greatest benefitto residents without undue impact on the existingbusiness. This may be accomplished by prioritisingthe various noise-control measures.

10.1.1 Steps in the process

This process may be triggered by a company pro-posal to partly upgrade its site, or by serious noisecomplaints. Where these occur the usual process is:

1. Measure and determine existing backgroundand ambient noise levels.

2. Measure the noise levels produced by thesource in question, having regard to meteoro-logical effects such as wind and temperatureinversion.

3. Determine project-specific noise levels fromintrusive and amenity noise criteria.


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4. Compare the measured noise level with theproject-specific noise levels.

5. Where the project-specific noise levels areexceeded, assess feasible and reasonablenoise mitigation strategies.

6. Negotiation between the regulator and thenoise source manager to agree to achievablenoise limits for the site. (This may involveconsultation with the community.) Regula-tory authorities and the noise-source man-ager need to consider the technical practicali-ties and cost of noise-reduction measures,along with the environmental consequencesof exceeding the project-specific noise levels.

7. Measures to achieve the limits by specifieddates may be set out in a noise reductionprogram.

8. Monitor compliance with the noise reductionprogram, and review and amend the programas required.

An example showing how this process works iscontained in Section A4 of Appendix A.

10.2 Noise reduction programs

The noise reduction program is reached throughagreement between proponent and regulator andwill typically have a statutory basis through condi-tions on a licence or notice. It will document theactions required to achieve the noise limits. Themeasures will generally be source- and site-specific,but could include the following elements:

• the aim and scope of the program

• identification of noise levels and targets forthe site

• an upper limit for new equipment

• an upper limit for partial upgrades of the site

• plans to eliminate problematic characteristicsthat have been identified, such as tonal andlow frequency noise

• a sound power limit for relevant sections ofthe site

• operating practices to reduce noise emissions

• training and awareness initiatives

• an ongoing monitoring program to evaluatenoise-emission levels

• communicating with the affected communityvia one or more of a complaints handlingprocess, liaison group, newsletters etc.

10.3 Noise-reduction strategies forexisting sites

Often the range of planning instruments that can beapplied to existing sites is limited. For example,planning approaches (for example, spatial separa-tion between source and receiver and attention tonoise reduction in designs for residential andindustrial buildings) that could avoid impacts aregenerally not available at this stage. Operationalprocedures and immediate cost-effective measuresthat can minimise noise with minimal impact on thenoise source should be identified and implemented.

The applicability, effectiveness and cost of particu-lar mitigation measures often depends strongly onsite variables. Section 7 provides advice on a rangeof typical mitigation strategies, and is a useful guidein deciding suitable mitigation measures for aparticular site.


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11 Reviewing performanceMonitoring of environmental noise levels from adevelopment to determine compliance with theconsent/licence conditions is essential to propermanagement of noise sources. This is the responsi-bility of the development proponent, and shouldgenerally be performed at specific stages of a devel-opment and/or as a result of complaints fromaffected receivers. A good monitoring programshould involve the community in reviewing theperformance of a development by providing thecommunity with:

• access to noise monitoring results

• an opportunity to discuss concerns andimpacts.

An additional way to monitor the performance of adevelopment is to establish a proponent-run com-plaints system. This is a beneficial managementtool, allowing further involvement of the communityin the performance review of a development.

The sections below outline the various methods forreviewing and managing the performance of adevelopment.

11.1 Monitoring environmental noise

11.1.1 Options for noise monitoring

Monitoring at specific stages of a development

This involves identifying the various stages of adevelopment where different noise outputs werepredicted during the assessment process, andmonitoring at each of these stages. For example, fora mine development, noise could be monitoredduring the first year of development and at four orfive other key years in the development of the mine(for example, years 2, 5, 10, 15 and 20).

To assess the performance of the developmentadequately, noise monitoring should cover the fullcycle of operational activity at each of the identifiedstages. Noise could be monitored over a full day(day, evening and night), a week, or longer—depending on the development.

It will usually be necessary to monitor noise atseveral sites, but these should at least include noise-

sensitive locations where noise levels are likely to bethe highest.

Monitoring as a result of community complaints

Another option is to monitor noise levels as a resultof community complaints. This may be done inaddition to noise monitoring at various stages of thedevelopment described above, or could stand aloneas the sole driver for performance monitoring.

With this option, noise should be monitored at thecomplainant’s premises. Monitoring should also beconducted to cover the time at which noise impactswere reported to occur.

11.1.2 Notes on noise monitoring

Items to be monitored

To check compliance with the consent/licencecondition, the following items require monitoring:

• noise levels from the development atlocations specified in the condition, or at thenearest affected receivers where no locationsare specified. During monitoring the metershould be set to ‘Fast’ time weighting and ‘A’frequency weighting and should recordusing the descriptor specified by theconsent/licence condition (that is, LAeq, 15 minute

or LAeq,period or other)

• the wind speed and direction

• sky cloud cover, using direct observation fornight measurements.

Where existing noise levels are high. When com-pliance is being measured it may be found that, inmany cases, existing noise levels are higher thannoise levels from the source, making it difficult toseparate out the source noise level. When thishappens, it may not be feasible to measure compli-ance at the specified location, and other methodswill be needed. In these cases, measurements maybe taken closer to the source and then calculatedback to the specified location. In doing this, takecare to account for the ‘near field’, a region in whichsound pressure levels do not decrease with distance


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in the normal way. Definitions of the extent of thisregion are contained in many noise textbooks (forexample, Bies & Hansen 1996). Any calculationsshould be done in accordance with the validationrequirements set out in Section 6.2.

Determining the noise contribution from a devel-opment. The following techniques may be used todetermine the LAeq contribution from a particularindustrial source from among multiple industrialnoise sources:

• measuring existing noise levels with andwithout the premises operating

• measuring the noise emissions from each ofthe premises at reference locations and thencalculating the noise-emission levels back tothe receiver

• using an accepted noise model calibrated forthe particular locality and source.

In the case where transportation sources exist, thenoise contribution from a development may bedetermined by isolating the transportation noiselevel using one of the methods outlined in Section3.2.1.

11.1.3 Non-compliances with noiseconditions

When is a development in non-compliance with anoise condition?

A development will be deemed to be in non-compli-ance with a noise consent or licence condition if themonitored noise level is more than 2 dB above thestatutory noise limit specified in the consent orlicence condition. This may occur for two reasons:

• The noise from the development is excessive,in which case the development is truly notcomplying with its consent or licencecondition.

• The noise was increased by extreme, non-standard weather effects—in which case thedevelopment is not considered to be in non-compliance with its consent or licencecondition. Non-standard weather effects canbe considered to be present duringmonitoring if the cloud cover is less than 40per cent and the wind speed (at 10 m height)

is less than 1.0 m/s (represents an extremelyadverse weather condition for noise)—duringthe period from 6 pm to 7 am in non-aridareas (see Section 9.2).

In this latter case, further monitoring at a later dateis required to determine compliance under themeteorological conditions specified in the consent/licence condition.

Managing non-compliances

Where the noise exceedance is found to be causedby excessive noise levels from a development, thedevelopment is considered to be in non-compliancewith its consent or licence condition. Strategies formitigation of noise need to be considered andimplemented, or a further negotiation process couldbe commenced.

When is a development in breach of a noisecondition?

A development will be in breach of a noise consentor licence condition if sustained non-compliancesare not addressed and rectified.

11.1.4 Items to be reported

The results of a noise monitoring test should beclearly reported and forwarded to the relevantauthority (if requested), or kept on file for reference.It is recommended that they also be made readilyaccessible to the community.

The following items are to be included in a noisemonitoring report:

• the type of monitoring test conducted (that is,the development stage or receiver complaints)

• the development noise limits on the consent/licence

• descriptions of the nearest affected receiversor, in the case of receiver complaints,description of the complainant andcomplaint

• the monitoring location—this should be atthe most affected point at or within thereceiver’s boundary or, if that is more than30 m from the receiver’s premises, at the mostaffected point within 30 m of the premises


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• the noise instrumentation used. (Theinstrumentation specifications required forcompliance monitoring are the same as thoserequired for background noise monitoring setout in Appendix B.)

• the weather instrumentation used. (Theinstrumentation specifications are the sameas those set out in Appendix E.)

• the weather conditions during noisemonitoring

• the time(s) and duration(s) of monitoring,including dates. In the case of receivercomplaints, these should coincide with thetime of the offence. In the case ofdevelopment-stage monitoring, these shouldcover the full cycle of activity.

• the results of noise monitoring at eachmonitoring location, including a comparisonwith the development limits

• a statement outlining the development’scompliance or non-compliance with the limit

• where noise exceedances are found (that is,the monitored noise level is higher than thelimit), the reasons for non-compliance shouldbe stated and strategies for managementidentified and stated as outlined in theprevious section

• where the noise exceedance is due toexcessive noise levels from the development,the strategies to be used to manage the noiseexceedance should be identified and stated.

11.2 Monitoring noise complaints

Where residual noise impacts have been negotiated,it is recommended that the proponent run a com-plaints-monitoring system. Components of such asystem could include:

• a complaint hotline to record receivercomplaints regarding the development

• a system for logging complaints and dealingwith them

• a database of complaints and theproponent’s responses/actions. This shouldbe readily accessible to the community andregulatory authorities

• a system for providing feedback to thecommunity. (This could be in the form ofregular meetings with affected residents, or anewsletter.)

Such a system is beneficial. It empowers the commu-nity and helps build an amicable rapport with theproponent. It also provides a useful mechanism forreviewing the performance of the development.


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12 Policy evaluation and review

The NSW EPA is committed to continual review ofthe policy procedures and criteria, to determine howappropriate the policy is. Three areas will be evalu-ated:

• policy procedures—through consultationwith acoustic practitioners, who collect theappropriate field data, apply the proceduresand assess noise impacts—to see howpracticable these procedures are

• policy framework—through consultationwith proponents and noise source managers,who negotiate the noise limits and developappropriate noise mitigation strategies—tosee how well this framework helps to derivethe noise levels incorporated in statutoryinstruments

• amenity levels—through consultation withcommunities affected by industrial noisesources to which the policy is applied—tohelp indicate whether amenity levels set inthe policy are adequate and are beingachieved.

A program of consultation will be developed togauge the policy’s effectiveness, once there has beensufficient time to allow the results of applying thepolicy to become evident. The outcome of the pro-gram will be to ascertain whether policy objectiveshave been fulfilled, and to suggest improvements.


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ReferencesBerglund B. & Lindvall T. (eds) 1995, ‘CommunityNoise’, Stockholm University and KarolinskaInstitute Archives of the Centre for Sensory Research onbehalf of the World Health Organization, vol. 2,issue 1, ISBN 91 887 8402 9.

Bies A. D. & Hansen C. H. 1996, Engineering NoiseControl, 2nd edn, E. & F. N. Spon, London.

Job R. F. S. 1996, ‘The Influence of Subjective Reac-tions to Noise on Health Effects of the Noise’,Environment International, vol. 22, no. 1, pp 93–104.

Luz, Lewis & Cloutier 1977, Analysis of Effects ofTemperature Inversions on Blast levels within 15 km ofArmy Weapons, US Army Environmental HygieneAgency.

NSW Environment Protection Authority 1994,Environmental Noise Control Manual.

NSW Environment Protection Authority 1999,Environmental Criteria for Road Traffic Noise.

WHO (World Health Organization) 1947, Thechronicle of the WHO, vol. 1. Geneva, quoted in Job R.F. S. 1996, ‘The influence of subjective reactions tonoise on health effects of the noise’, EnvironmentInternational, vol. 22, no. 1, pp 93–104.


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Definitions of termsAcceptable noise level: See the fourth column of

Table 2.1.

A-weighted: See dB(A).

Adverse weather: Weather effects that enhancenoise (that is, wind and temperature inver-sions) that occur at a site for a significantperiod of time (that is, wind occuring morethan 30% of the time in any assessmentperiod in any season and/or temperatureinversions occuring more than 30% of thenights in winter).

Ambient noise: The all-encompassing noiseassociated within a given environment. It isthe composite of sounds from many sources,both near and far.

Amenity criteria: See Tables 2.1 and 2.2.

Assessment period: The period in a day overwhich assessments are made: day (0700 to1800 h), evening (1800 to 2200 h) or night(2200 to 0700 h).

Assessment background level (ABL): The single-figure background level representing eachassessment period—day, evening and night(that is, three assessment background levelsare determined for each 24-h period of themonitoring period). Its determination is bythe tenth percentile method described inAppendix B.

Background noise: The underlying level of noisepresent in the ambient noise, excluding thenoise source under investigation, whenextraneous noise is removed. This is de-scribed using the LA90 descriptor.

Breach: Failure to address and rectify sustainednon-compliance will place a development inbreach of its noise consent/licence condition.

C-weighted: C-weighting is an adjustment made tosound-level measurements which takesaccount of low-frequency components ofnoise within the audibility range of humans.

Cognitive noise: Noise in which the source isrecognised as being annoying.

Community annoyance: Includes noise annoyancedue to:

—characteristics of the noise (for example,sound pressure level, tonality, impulsive-ness, low-frequency content)

—characteristics of the environment (forexample, very quiet suburban, suburban,urban, near industry)

—miscellaneous circumstances (for example,noise avoidance possibilities, cognitivenoise, unpleasant associations)

—human activity being interrupted (sleep,communicating, reading, working, listen-ing to radio/TV, recreation).

Compliance: The process of checking that sourcenoise levels meet with the noise limits in astatutory context.

Construction activities: Activities that are related tothe establishment phase of a developmentand that will occur on a site for only a limitedperiod of time.

Cumulative noise level: The total level of noisefrom all sources.

Day: The period from 0700 and 1800 h (Monday toSaturday) and 0800 to 1800 h (Sundays andPublic Holidays).

dB: Abbreviation for decibel—a unit of soundmeasurement. It is equivalent to 10 times thelogarithm (to base 10) of the ratio of a givensound pressure to a reference pressure.

dB(A): Unit used to measure ‘A-weighted’ soundpressure levels. A-weighting is an adjustmentmade to sound-level measurement to ap-proximate the response of the human ear.

Default parameters: In assessing meteorologicalenhancement of noise, refers to set values forweather parameters, such as wind speedsand temperature gradients, to be used inpredicting source noise levels.

Equivalent continuous noise level: The level ofnoise equivalent to the energy average ofnoise levels occurring over a measurementperiod.

Evening: The period from 1800 to 2200 h.

Extraneous noise: Noise resulting from activitiesthat are not typical of the area. Atypical


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activities may include construction, andtraffic generated by holiday periods and byspecial events such as concerts or sportingevents. Normal daily traffic is not consideredto be extraneous.

Feasible and reasonable measures: Feasibilityrelates to engineering considerations andwhat is practical to build; reasonablenessrelates to the application of judgement inarriving at a decision, taking into account thefollowing factors:

—noise mitigation benefits (amount of noisereduction provided, number of peopleprotected)

—cost of mitigation (cost of mitigation versusbenefit provided)

—community views (aesthetic impacts andcommunity wishes)

—noise levels for affected land uses (existingand future levels, and changes in noiselevels).

Greenfield site: Undeveloped land.

High traffic criterion: See Section 2.2.3.

Impulsive noise: Noise with a high peak of shortduration, or a sequence of such peaks.

Industrial noise sources: Sources that do notgenerally move from place to place, forexample, stationary sources. Except whereother more specific guidelines apply (forexample, construction activities, road or railtraffic, emergency diesel generators etc), allindustrial noise sources that are scheduledunder the Protection of the Environment Opera-tions Act 1997 are considered to be industrialsources. In general, these include:

• individual industrial sources such as:

—heating, ventilating and air conditioning(HVAC) equipment

—rotating machinery

—impacting mechanical sources

—other mechanical equipment and machin-ery such as conveyors

—mobile sources confined to a particularlocation, such as draglines and haultrucks.

• facilities, usually comprising many sourcesof sound,including:

—industrial premises

—extractive industries

—commercial premises

—warehousing facilities

—maintenance and repair facilities.

(In this case, the industrial source isunderstood to encompass all the activitiestaking place within the property boundaryof the facility.)

Intrusive noise: Refers to noise that intrudes abovethe background level by more than 5 decibels.The intrusiveness criterion is set out inSection 2.1.

LA90: The A-weighted sound pressure level that isexceeded for 90 per cent of the time overwhich a given sound is measured. This isconsidered to represent the backgroundnoise.

LAeq: The equivalent continuous noise level—thelevel of noise equivalent to the energy-average of noise levels occurring over ameasurement period.

Low frequency: Noise containing major compo-nents in the low-frequency range (20 Hz to250 Hz) of the frequency spectrum.

Masking: The phenomenon of one sound interfer-ing with the perception of another sound. Forexample, the interference of traffic noise withuse of a public telephone on a busy street(Bies & Hansen 1996).

Maximum noise level: See the fifth column of Table2.1.

Median: The middle value in a number of valuessorted in ascending or descending order.Hence, for an odd number of values, thevalue of the median is simply the middlevalue. If there is an even number of values themedian is the arithmetic average of the twomiddle values.

Meteorological conditions: Wind and temperature-inversion conditions.


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Most affected location(s): Locations that experi-ence (or will experience) the greatest noiseimpact from the noise source under consid-eration. In determining these locations, oneneeds to consider existing background levels,exact noise source location(s), distance fromsource (or proposed source) to receiver, andany shielding between source and receiver.

Negotiated agreement: An agreement involvingthe negotiation of an achievable noise limit incases where the project-specific noise levelscannot be met. The agreement is negotiatedbetween the proponent and the EPA or theproponent and the community. Such anagreement is reached through balancing themerits of a development, the feasibility andreasonableness of available mitigationmeasures and the noise impacts produced.

Noise criteria: The general set of non-mandatorynoise level targets for protecting againstintrusive noise (for example, backgroundnoise plus 5 dB) and loss of amenity (forexample, noise levels for various land uses).

Noise limits: Enforceable noise levels that appearin conditions on consents and licences. Thenoise limits are based on achievable noiselevels which the proponent has predicted canbe met during the environmental assessment.Exceedance of the noise limits can result inthe requirement for either the development ofnoise management plans or legal action.

Night: The period from 2200 to 0700 h (Monday toSaturday) and 2200 to 0800 h (Sundays andPublic Holidays).

Noise-sensitive land uses: Land uses that aresensitive to noise, such as residential areas,churches, schools and recreation areas.

Non-compliance: A development is deemed to be innon-compliance with its noise consent/licence conditions if the monitored noiselevels exceed its statutory noise limit by morethan 2 dB.

Non-mandatory: With reference to the proposedpolicy, means not required by legislation. Theproposed policy specifies criteria to be strivedfor, but the legislation does not make thesecriteria compulsory. However, the policy willbe used as a guide to setting statutory (legallyenforceable) limits for licences and consents.

Operator: Noise-source manager

Performance-based goals: Goals specified in termsof the outcomes/performance to be achieved,but not in terms of the means of achievingthem.

Project-specific noise levels: Project-specific noiselevel are target noise levels for a particularnoise generating facility. They are based onthe most stringent of the intrusive criteria oramenity criteria. Which of the two criteria isthe most stringent is determined by measur-ing the level and nature of existing noise inthe area surrounding the actual or proposednoise generating facility.

Proponent: The developer of the industrial noisesource.

Protection of the Environment Operations Act1997: An Act that consolidates air, water,noise and waste requirements into a singlepiece of legislation. This Act repeals andreplaces (among other Acts) the Noise ControlAct 1975.

Rating background level (RBL): The overall single-figure background level representing eachassessment period (day/evening/night) overthe whole monitoring period (as opposed toover each 24-h period used for the assess-ment background level). This is the level usedfor assessment purposes. It is defined as themedian value of:

—all the day assessment background levelsover the monitoring period for the day

—all the evening assessment backgroundlevels over the monitoring period for theevening; or

—all the night assessment background levelsover the monitoring period for the night.

Receiver: The noise-sensitive land use at whichnoise from a development can be heard

Significant period of time: In relation to tempera-ture inversions, means at least 30 per cent ofthe total night-time during the wintermonths. In relation to wind speeds thismeans at least 30 per cent of the time or morein any assessment period (day, evening,night) in any season.

Sleep disturbance: Awakenings and disturbanceto sleep stages


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Spectral characteristics: The frequency content ofnoise.

Temperature inversion: An atmospheric conditionin which temperature increases with heightabove the ground.

Temporal variation of noise: Variation in noiselevels over time.

Tenth percentile method: See Appendix B.

Time of maximum impact: The time during whichthe difference between the background noiselevel and the source noise is expected to begreatest.

Tonality: Noise containing a prominent frequencyand characterised by a definite pitch.

Transportation: Includes road, rail and air traffic.

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