November 2004 (PDF 11.6 MB) - Barrick Gold Corporation

ackground level as the mid-point value betweenthe rating background levels of the two assessmentperiods that are on either side of the shoulderperiod.The objective is to achieve environmental amenity ina feasible and reasonable manner. In an assessmentof the likely level of noise impact, the time of day isonly one of several relevant factors—such as noiselevel and character, and the activities affected by thenoise. Noise of a lower level, and with no intrusivecharacteristics such as tones and impulses, canoften be more acceptable over a longer period of theday than noise at a high level and/or with intrusivecharacteristics.3.4 Meteorological conditions formonitoringWind and rain conditionsNoise monitoring should not be conducted (or thedata should be excluded) when average windspeeds (over 15-minute periods or shorter) at microphoneheight are greater than 5 m/s, or whenrainfall occurs. Exceptions to this rule are allowed,provided the proponent is able to show that thewind-induced noise on the microphone, and soundlevels due to rain, are at least 10 dB below the noiselevels (that is, background and/or ambient) underinvestigation.Where high wind speeds are a feature of the area,monitoring may be permitted during higher windspeeds, provided the proponent is able to show thatthese wind speeds are a site feature and that thewind-induced noise on the microphone is at least 10dB below the noise levels under investigation.Wind blowing through leaves can raise the environmentalnoise levels, even at speeds less than 5 m/s.To avoid this effect, take care to select monitoringlocations that are as far away as possible fromvegetation while still being representative of thesubject site.Temperature inversionsThe noise levels determined using the methods justdescribed are considered to represent the season inwhich they have been monitored. For this reason,monitoring may be conducted during temperatureinversion conditions to ensure that the noise environmentat a site is adequately represented. However,care is needed when doing short-term measurementsto ensure that the measured noise levelresults in an adequate assessment of impacts. Forinstance, measurement of short-term backgroundnoise should exclude any data collected duringtemperature inversions where these inversions areinfrequent and are not a feature of the area. Otherwiseassessment applying the intrusiveness criterionwill not adequately assess the noise impact.Seasonal variationsThe EPA recognises that background noise levelsmay vary due to seasonal changes in weatherconditions and wildlife activity (for example,insects, birds and other fauna) and also as a resultof changes in operational activities on surroundingdevelopments. As far as is practicable, these potentialchanges should be considered and addressed ina qualitative manner in the noise assessment reportto ensure that noise impacts during other seasonsare not ignored.Such changes may be accounted for by excludingthe season-related noise levels from the backgroundnoise measurements by filtering or other means (forexample, in the case of seasonal operational activities,by monitoring in a similar location not affectedby the development in question). In other casesthese variations may be discounted on the basis oflocal knowledge in the area, but the discountingshould still be justified in the noise assessmentreport.3.5 Duration of monitoringScreening tests may be performed before any monitoringto assess whether monitoring is required. Forexample, if a minimum background noise level of 30dB(A) is assumed as the rating background leveland the assessment shows no impact, then there isno need for background noise monitoring, as thisrepresents a conservative and limiting case.Typically, one week’s worth of valid data coveringthe days and times of operation of the proposeddevelopment is required to meaningfully determinethe existing noise environment. However, theduration of monitoring should be determined bytaking into account the circumstances of the particularsituation. The cyclic or random nature ofNSW industrial noise policy26