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 30 of 79 6.4 Processing Plant The Processing Plant will be upgraded to facilitate the additional throughput and extended lifespan resulting fromWNP. While the plant upgrade may not necessarily occur immediately on the grant of consent, our calculations have assumed that this does happen as a worst case. As we set out in Section 4.1, all the activity occurring for the Processing Plant upgrades is considered as construction noise. This means that less stringent noise criteria would apply. However, we note that the adoption of the BPO is still mandatory. The main aspects of this upgrade are: • Replacing the current pre-feed crusher with primary crushing plant relocated from Reefton; • Replacing the existing SAG mill with that from Reefton; • Replacing the existing pebble crusher; • Installing a new ball mill adjacent to the new SAG mill; • Converting the existing SAG mill into a ball mill; • Additional car parking areas near Martha mine, and Baxter Street; and • New substation with associated transformers and switchgear. While some large new items of plant are proposed, this is expected to only have a relatively small effect on overall noise emissions from the Processing Plant. The modelled major component sound power levels are as follows: Ball mill (open): 113 dB LwA Jaw crusher: 113 dB LwA Primary crusher: 119 dB LwA Mobile crusher: 117 dB LwA Cyclones: 98 dB LwA SAG mill: 116 dB LwA We understand that the existing Water Treatment Plant (WTP) will also be upgraded to around double the current capacity, but that no newmajor noise sources are anticipated for the operation of this part of the project. Figure 16 demonstrates the change in noise level after the Processing Plant upgrade. This is based on the existing topography and represents the Processing Plant alone, without inclusion of noise from other mining operations. This allows an assessment of the change in noise emission from the Processing Plant only and is useful because there are some occasions when other proximate mining operations may not actually be occurring. The calculations show that there is a general increase in noise levels as a result of the Processing Plant upgrades but also a small decrease to the south-west. For the relevant receivers (Barry Road environs), noise levels increase by approximately 3-5 dB. This is a barely discernible to just noticeable increase. Taking account of the fact that generally, other mining operations often contribute more noise to these receivers, increased Processing Plant noise levels are unlikely to be discernible for much of the time. For context, the mean noise level increase at all receivers analysed is 3 dB. Of the few that have a calculated increase of up to 5 dB, the Processing Plant contribution is still below 40 dB LAeq, compared with overall mining noise levels of around 45 dB LAeq. This means that the Processing Plant will still be an audible source of noise (relative to other mining operations) but will not be dominant – the relative noise levels of most significant mining plant will be broadly similar. Those that receive the highest levels of Processing Plant noise up to 44 dB LAeq – are subject to a less notable increase and are generally the most affected by all noise from the Gladstone project area. Again, the Processing Plant will not be an exceptional noise source within the wider WNP. Overall noise emissions for the processing plant are compliant during the day. However, as shown above for the worst affected receivers, it is possible that noise levels at night may just exceed the night-time noise limit of 40 dB by a small margin. As the processing plant design is not possible to accurately model at this stage because the equipment is relatively unique, being sourced from other OGNZL sites around the country, and is currently not operational so we cannot measure the noise emissions, we have necessarily included some conservatism in the calculations. This means it is possible that once established on site, there is likely to be lower noise levels in practice. In any event, and as for Gladstone, the proposed conditions require that a noise management plan (NMP) be prepared to outline the methods to be used to ensure noise levels do not exceed 40 dB at any residence not owned by OGNZL or subject to or with an agreement with OGNZL. The mitigation methods would include (but not be limited to); • Restrictions on operating hours • Bespoke screening of individual sources (primarily by the use of full enclosures) • Screening of noise sensitive receivers • Noise monitoring programmes (including detailed noise modelling of the new plant when installed and measurement regimes) On this basis and with the above measures in place, we consider the processing plant noise emissions would be able to comply with the noise limits in the proposed conditions, and therefore would be reasonable from a noise effects perspective.
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