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 28 of 79 6.3 Operational Noise Emissions Noise from the Gladstone operations, in addition to the Processing Plant and WUG Portal, will be one of the primary aspects of WNP in terms of noise effects on receivers. Receivers on both the northern and southern sides of Gladstone Hill will experience noise from these works. As previously indicated, the early years – 2024 to 2026 – will be most critical for noise emissions, because large mining plant will be used and the machinery will be at a relatively shallow level in the pit. We have predicted noise levels at the selected representative receivers identified in Section 5.1.2. During the course of our analysis it became clear that additional dwellings would need consideration for Gladstone. This is because we observed there are a number of localised and discrete areas where noise levels may potentially be above 50 dB, primarily on Barry Road, Knowles Crescent and Moore Street and to a lesser extent George Street. Figure 15 overleaf shows just the 50 dB LAeq cumulative noise emission contours for these three years (assuming no mitigation) and the location of the representative receivers. This Figure shows there are a number of receivers located near the 50 dB LAeq contour and a couple of receivers just inside the contours. This figure should form the starting point of investigations, prior to works commencing, on what mitigation options shall be considered to ensure noise levels comply with the proposed noise limits. The discrete noise levels at the representative receivers and the additional receivers, are given in Table 12 below. Table 12: WNP Noise levels at all receiver locations Representative Receiver (Figure 15) Receiver Address Calculated Noise Level per Year, dB LAeq 2023 2024 2025 2026 2027 2028 2029 2030 2031-34 4 (West) 14 George Street - 48 51 49 46 45 45 40 43 11 (North) 55 Barry Road 38 52 51 50 50 50 50 42 46 12 (North) 10 Moore Street 38 53 52 52 51 51 50 43 48 13 (North) 72 Barry Road 39 54 53 52 51 51 51 44 46 16 (West) 33A Heath Road - 51 54 53 50 48 48 43 46 18 (South) 36 Baxter Road - 51 49 48 47 46 46 38 44 Additional Identified Receivers 13 Banks Street 37 52 50 49 48 48 48 41 44 16 Banks Street 39 51 50 49 48 48 48 43 47 49 Barry Road 37 52 51 50 50 49 49 42 46 59 Barry Road 38 52 49 48 46 45 45 41 43 56 Barry Road 39 55 54 53 53 52 52 45 49 58 Barry Road 41 55 54 53 52 52 52 45 49 73 Barry Road 39 51 49 47 47 47 47 42 44 76 Barry Road 39 51 49 48 46 46 46 42 44 80 Barry Road 39 51 48 46 45 45 45 41 42 10 George Street <30 48 51 48 47 45 45 40 43 12 George Street <30 48 51 48 46 44 44 40 43 16 George Street <30 49 51 49 46 45 44 40 43 18 George Street <30 49 51 48 45 44 44 40 43 Representative Receiver (Figure 15) Receiver Address Calculated Noise Level per Year, dB LAeq 2023 2024 2025 2026 2027 2028 2029 2030 2031-34 17 Heath Road <30 48 51 51 49 47 46 40 43 23 Heath Road <30 48 52 51 49 47 46 40 43 29 Heath Road <30 49 51 51 48 45 45 39 45 2 Knowles Crescent 38 51 49 48 47 47 47 42 45 2A Knowles Crescent 38 52 51 50 49 49 48 43 47 3 Knowles Crescent 38 52 50 50 49 49 49 44 47 5 Knowles Crescent 38 52 50 50 49 49 49 44 47 3 Moore Street 39 54 53 52 52 51 51 44 49 Legend: Potentially reduced by further mitigation. It can be seen that unmitigated noise levels are predicted to be above 50 dB LAeq at 27 receivers (51 to 55 dB LAeq) in relation to works in the Gladstone area for approximately one to six years. With respect to the actual noise effects for receivers at 51 to 55 dB LAeq, the adverse effects of noise are not a ‘binary’ effect that switch on/off at 50 dB. It is not true to say that there are no adverse effects at 49 dB and there are significant adverse effects at 51 dB. Noise effects gradually increase with noise level on a ‘grey scale’. For this project it has been determined that 50 dB is an appropriate objective to keep the noise level below as the adverse effects at this point are reasonable and would be acceptable to most people. 21 of these 27 receivers are predicted to experience 51 to 52 dB LAeq for one to three years. The other six dwellings are predicted to experience 53 to 55 dB LAeq for one to four years with smaller exceedances for a further one to four years. These are all located on Barry Road and Moore Street. For some years the noise level is only one to two decibels above the criteria. In terms of the effect when noise is above 50 dB, we note that: • For noise levels, at 51 and 52 dB (21 receivers) the effects are not discernibly different to 50 dB – they are higher than the objective, but not discernibly different. • For noise levels at 53 dB to 55 dB (6 receivers) the adverse effect becomes more discernible, and warrant mitigation. Overall, it is our opinion that noise levels in excess of 50 dB LAeq would have a small adverse impact on the level of amenity these properties experience. This is primarily for those few houses where the exceedance is three to five dB. For those with just a one decibel exceedance the adverse impact on the level of amenity is very small. We reach these conclusions based on the existing noise environment (39 dB LA90 & 46 dB LAeq), and the general lack of existing exposure to mining noise in this area. This is as well as the overall noise level received, including the periods during the week when that noise is experienced. Despite there being a barely discernible difference in noise level between 50 dB and 53 dB, it is just sufficiently high to cause an impact. Notwithstanding this, and to put into context these small exceedances, the District Plan already contains a rule effectively permitting the nearby process plant to emit noise at 55 dB LAeq (referenced in Rule 5.17.4.1 of the District Plan). This suggests the Council already envisages mining noise in this local area, and in the wider district. In addition, and as noted in Section 5.1, these calculations are considered conservative because they are prepared on the assumption that receivers are always downwind of the noise source – a small increase in propagation towards them. This is not always the case in practice and the noise levels will often be less than predicted.
RkJQdWJsaXNoZXIy MjE2NDg3