November 2004 (PDF 11.6 MB) - Barrick Gold Corporation

6 Predicting noise levels & determiningimpactsAn 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 parametersThe important parameters for predicting noise arelisted below. These will set the boundaries of thenoise prediction process. They need to be determinedand 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 surroundingland uses) that affect noise propagation• operating times of the development.6.2 Noise predictionTo quantify the noise impact, the noise levels fromthe source at all potentially affected receiversshould be predicted, taking account of the parametersidentified (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:• L Aeq,periodif the amenity criteria establish theproject-specific noise levels• L Aeq,15 minuteif the intrusive criterionestablishes the project-specific noise levels.Any assumptions made when determiningdescriptors should be clearly validated and reportedin 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 models.Such models generally take account of noiseattenuation due to distance, atmospheric absorption,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 acceptedpractice (for example, Environmental NoiseModel (ENM) or Soundplan). Any other modellingapproaches used would need to be validated beforeNSW industrial noise policy36