November 2004 (PDF 11.6 MB) - Barrick Gold Corporation

Special care needs to be taken when doing shorttermmeasurements 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, lawnmowing,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 backgroundlevels, 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 representativeof 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 singlefigurebackground level representing each assessmentperiod—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 operationof the proposed development are required tobe assessed.Rating background level (RBL)—the overall singlefigurebackground level representing each assessmentperiod (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 L A90,15 minutelevel. 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 measurementsTransportation 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 measurementshould not include transportation noise,otherwise incorrect high readings will result.However, where the traffic is constant and continuous,transportation may be included in the shorttermmeasurement to ensure that the noise environmentis adequately represented.3.2 Determining existing noise levelsfor amenity criteriaExisting noise levels need to be determined for theperiods during which the proposed developmentwill operate.In determining the existing L Aeqnoise level, it isimportant to obtain a representative level. Hence,NSW industrial noise policy24