November 2004 (PDF 11.6 MB) - Barrick Gold Corporation

any assessment period in any season, thenthe default wind speed of 3 m/s should beused in the assessment for the particularassessment period/s and season/s where itoccurred.• If the wind rose shows that a source-toreceivercomponent of wind less than3 m/s occurs for at least 30 per cent of thetime in any assessment period in any season,then the highest wind speed (below 3 m/s)may be used instead of the default.• If the wind rose shows that there is less than30 per cent occurrence of source-to-receivercomponent wind speeds up to 3 m/s, thenwind is not included in the noise predictioncalculation.Assessing the impactThe parameters for wind direction and speed arethen used to predict increased noise levels, whichare then compared with the project-specific noiselevels derived in the previous section for case (a) todetermine what the noise impact will be.A4Existing premises case studyIn dealing with noise impacts from existingpremises it needs to be recognised that the meansavailable to mitigate noise may be more limited thanfor new premises. For example, planning approachesthat could avoid impact are generally notavailable at this stage (for example, spatial separationbetween source and receiver and attention tonoise reduction in designs for residential andindustrial buildings). Measures such as consideringnoise impacts when laying-out buildings on theindustrial premises and when selecting equipmentwill be more limited, and may be a feasible considerationfor existing premises only in the longer term.In treating existing cases it is often necessary to takea structured approach to mitigation that starts withdefining the problem, then identifies the range offeasible and reasonable controls that can be applied,then implements noise controls over time.The following example provides a summary of howan existing premises with a noise problem can beaddressed.Example:An existing scheduled premises is receiving complaintsabout noise from neighbouring residences.Currently the premises has no noise limits on itslicence.The EPA and the company have contacted complainantsand it appears the complainants mayhave a genuine grievance.The next step is to ascertain whether in fact there isa noise impact (that is, noise levels exceedingapplicable project-specific noise levels for the site).After discussions with the residences the companyagreed to the EPA’s request to conduct a noisesurvey. The survey, conducted by an accreditedacoustics practitioner, covered the following items:• identified the most affected residences• identified the activities on the site that causedthe reported annoyance• conducted a noise assessment without theexisting premises operating, includingbackground (L A90, 15 minute) and ambient(L Aeq, 15 minute) noise levels. (The short-term orlong-term background and ambient noisemethods may be used, depending on theextent of noise impact.)• determined project-specific noise levels basedon EPA noise criteria and applying theexisting background and ambient noiselevels• measured noise levels from the site at theidentified affected residences. (Whereapplicable, include adjustments to takeaccount of any annoying characteristics ofthe noise.)• compared measured noise levels (adjusted,where necessary) against the project-specificnoise levels to determine the extent of impact• discussed whether noise impacts may beincreased by weather patterns (for example,winds and temperature inversions) typical tothe area and estimated the extent of theincrease• discussed mitigation measures and theamount of noise reduction expected fromeach measureNSW industrial noise policy65