November 2004 (PDF 11.6 MB) - Barrick Gold Corporation

Table 3.2. Determining the existing L Aeqnoise levelsRisk of noise impact Measurement period 1 Definition of existing levelLow riskHigh riskOne day—covering the definedday/evening/night periods relevant to theperiods the proposed development wouldoperate.One week—covering the definedday/evening/night periods the proposeddevelopment would operate.The logarithmic average 2 ofindividual L Aeq,15 minutelevels for eachday/evening/night assessmentperiod over the measurementperiod.Notes:1. It is recommended that the L Aeq be measured on a 15-minute basis.2. Logarithmic average = 10log 10 ((∑ i=1 to n 10 (LAeq,15 min,i/10) )/n), where n = number of L Aeq,15 min values in eachassessment period over the measurement period.assessing the existing L Aeqnoise level is as definedin Table 3.2 for assessing different noise risk developments.3.2.1 Excluding transportation noiseThe ‘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 amenitylevel. 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 industrialsource noise levels are equivalent, buttransportation noise is much lower.3. Modelling the level of transportation noiseand subtracting the result from the measuredcombined 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 assessmentposition, causing traffic on it to be the dominantsource of noise at the site.3.3 Dealing with ‘shoulder’ periodsThere will be situations that call for different assessmentperiods. 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 situations,appropriate noise level targets may be negotiatedwith the regulatory/consent authority on acase-by-case basis. As a rule of thumb it may beappropriate to assign a shoulder period ratingNSW industrial noise policy25