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 35 of 79 8.0 TAILINGS STORAGE FACILITIES NOISE CALCULATIONS Another consequence of the expanded mining operation is the need to create additional capacity for tailings storage. Expansion is already planned to the capacity of facilities TSF1A and TSF2, to meet existing operational requirements. A new facility will be constructed for WNP: TSF3. The Gladstone TSF will also provide some capacity in future years. The schedule below in Table 13 indicates the planned tailings deposition and construction periods over the course of the WNP lifespan (including the already consented facilities*). Table 13: Indicative tailings storage schedule Storage Destination Year 23 24 25 26 27 28 29 30 31 32 33 TSF1A* < Storage TSF2 raise* TSF1A raise* TSF3: 135m TSF3: 145m TSF3: 155m GOP TSF S1 GOP TSF S2 Construction > The key TSF activity areas are shown in Figure 20. Details around the new Gladstone storage facility were previously discussed in Section 6.0. 8.1 Tailings Storage Facility 3 The new facility will be approximately 53 m in height and have a target crest height of 1155 mRL and a 50 m wide crest. As shown in Figure 20, its construction will bring OGNZL’s activities closer to existing rural dwellings on Trig Road North. The closest dwellings (e.g. 131 Trig Road North) will be around 250 metres from the outer extent of TSF3 and associated stockpiles. There will be little operational noise associated with any of the facilities, once constructed. Construction activity will, however, result in periods of elevated noise levels in the vicinity of the TSFs. With the exception of the initial foundation earthworks and specific other works (Table 1) the overall TSF3 construction activity is sufficiently long and similar in character to normal mining activities that we consider it as an ‘operational’ activity, rather than ‘construction’. Noise emissions from these activities should therefore be considered against the operational noise limits outlined in Section 4.0, rather than the less stringent construction noise limits. However, topsoil stockpiles, the clean water diversion drains and haul road construction is treated and assessed as construction noise. It can be seen in Figure 20 that noise levels are generally higher to the southern side, with lower noise emissions to the west and to the east, partially because of more effective screening by terrain and TSF 1A. Overall, noise levels from worst case TSF3 construction are below 50 dB LAeq. We note that any activity that occurs at night has to meet the much more stringent night-time noise limit of 40 dB. Whilst this noise limit does allow for some activity to be undertaken, it does mean night-time activity will necessarily be at a much lower intensity in order to comply. Any proposed night-time activity needs to be carefully considered in the NMP, required by the conditions, to ensure compliance. Figure 20: Designation of main tailings storage facilities (TSF1, 2 & 3)
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