November 2004 (PDF 11.6 MB) - Barrick Gold Corporation

able to show that the wind-induced noise on themicrophone and sound levels due to rain are atleast 10 dB(A) below the background noise levelsunder investigation. For sites where high windspeeds are a feature of the area, monitoring may bepermitted during higher wind speeds provided thatthe proponent is able to show that these windspeeds are a site feature and that the wind-inducednoise on the microphone is at least 10 dB(A) belowthe noise levels under investigation.B1.2 Measurement procedureThe steps involved in monitoring background noiselevels for planning purposes are:1. Calibrate the noise monitoring equipment inthe field.2. Monitor the background noise and meteorologicalconditions continuously for each dayof the week the proposed development will beoperating and over the proposed operatinghours, using the L A90,15minutedescriptor.3. Note dominant and background noisesources present at the site throughout themonitoring period. Simultaneous datalogging and tape-recording of noise levelsand operator-attended measurements may bemade at the site to support the identificationand occurrence of noise sources.4. Do a field calibration check at the end of themonitoring period in accordance withAS1259 and AS2659. Re-monitoring may berequired if there is a calibration drift greaterthan that allowed by the standards.B1.3 Analysis procedure1. Remove any data that are affected by adverseweather conditions and/or extraneous noise.Check that the number and pattern of excludedL A90,15 minutesamples complies with therules specified in Figure B1. If it does not, remonitorthe background noise followingsteps 1 to 4, but only for the affected assessmentperiod in the corresponding day of theweek. The underlying idea is to ensure thatany patterns that occur are accounted for.These are often seen temporally throughout aday, diurnally, and from weekday to weekend.Exception: re-monitoring may not be requiredwhere monitoring contains weather-affecteddata if it can be ascertained that the affectedsamples are not within the expected ‘quieter’times of an assessment period (day/evening/night)—that is, those time periods where thelowest tenth percentile background noiselevel might occur. In this case it should befully justified in the noise-assessment reportthat the weather-affected data would notaffect the lowest tenth percentile backgroundnoise level. This could be done through theclear identification of set daily noise patternsof ‘quiet’ periods exhibited by the measureddata from the non-affected days. Thereshould be enough non-affected data availablefor the assessor to be confident that anypattern identified is valid. For these cases theaffected samples need not be removed fromthe data set before the tenth percentile isdetermined in Step 2.Figure B1. Data exclusion rule1. For every 4 consecutive values (-) there should be no more than 2 samples missing (x), for e.g.:Single invalid 15-minute samples: - - - x - - - x - - - x - - - or- - x - - x - - x - - x - - or- x - x - x - x - x - x -Double invalid 15-minute samples: - - x x - - x x - - x x - -2. Where the maximum number of invalid samples (x) is greater than 8, 2 or 4 for day, evening and nightrespectively, then the corresponding period (day/evening/night) should be monitored again.3. Where there are more than two consecutive invalid (x) samples, only one occurrence of the followingpattern is allowed before re-monitoring is required.Triple invalid 15-minute samples: - - - x x x - - -NSW industrial noise policy69