November 2004 (PDF 11.6 MB) - Barrick Gold Corporation

2 Industrial Noise CriteriaThe 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 magnitude(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 impactsThe 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 L Aeqdescriptor), 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 components,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:L Aeq, 15 minute≤ rating background level plus 5where :L Aeq, 15 minuterepresents 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 measuringthe 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 characteristicsof 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 experienceNSW industrial noise policy14