This document may not be reproduced in full or in part without the written consent of Marshall Day Acoustics Limited Rp 001 R0 20210601 SJP (Waihi North Noise Assessment) ISSUE 25 of 79 activities by defining trigger levels for mitigation action. Examples of the typical noise propagation for conventional equipment are given in Figure 11 below. The data indicate that, for noise from individual sources, compliance with the 75 dB LAeq construction noise limit for typical duration works (see Section 2.2.2) is achieved at distances from below 5 metres up to 30 metres, depending on the type of source. However, noise levels could be increased where multiple equipment operates simultaneously. Therefore, in addition to this generalised assessment method for construction noise, we have also given further consideration to some specific construction activities that are considered more high risk, factoring the cumulative noise frommultiple activities or equipment. Figure 11: Noise level regression for typical construction equipment These are addressed in the respective report sections for each component, and in particular relate to: • Willows Road and SH25 works (these being the primary off-site construction works). • Stripping of Gladstone Hill down to 1142 mRL. • Initial portal construction (adjacent to the Processing Plant). • Stockpile preparation at the NRS and TSF3 worksites. While these are not representative of every stage of activities, the examples are provided to demonstrate how different receivers may be affected from any given activity. 5.3 Helicopter Noise Aircraft construction noise calculations have also been undertaken in relation to the WUG support flights. Modelling software called the Integrated Noise Model (INM) has been used to predict LAeq and LAmax noise emissions from the proposed helicopter operations for comparison with the construction noise standard criteria. The INM is produced by the Federal Aviation Administration (FAA) of the United States and is widely used internationally for modelling noise emissions from airports and heliports. It is proposed to approach and depart each vent raise from a site close to the Golden Cross mine car park or on occasion from the Baxter Road helipad. These are located at some distance from the nearest residential activity. It is proposed to operate standard contractor-type helicopters, such as AS350 or EC130s. A specific helicopter profile that includes time on the ground with the engine and rotor operating before a departure and after an arrival, and helicopter hover time in the vicinity of the vent raise has been developed. The likely hover duration and hover altitude has been provided by OGNZL and specifically included in the modelling. We understand that a worst-case number of movements per campaign of 20 flights (in this case each flight is assumed to be arrive – hover – depart) over 4 days, followed by 10 identical flights over 2 days about a week later. As such, in any one 15 minute period there would simply be one flight using the above-mentioned profile. There is also one service flight per day during the campaign. Figure 28 shows the calculated LAeq (15min) noise contours and the calculated LAmax noise contours at some typical raise locations. The equivalent noise levels at other raises not shown in Figure 27 would also occur. We note that this is for a typical campaign and at other times of the exploration helicopter noise levels would likely be lower, with less, if any, hover activity.
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