| Potential Effects on the Environment of WNP | Waihi North Project Air Discharge Assessment - Waihi Surface Facilities | 4396626-1331619777-99 | 16/06/2022 | 61 7.5 Potential Health Effects of Fine Particulates, Respirable Silica, Combustion Emissions from Vehicles and Blast Emissions Most of the particulate matter generated from the proposed WNP will be of a larger-size fractions rather than PM10 or PM2.5 (refer Section 3.2.1). Emissions from the WNP dust generation are therefore expected to make only a relatively small contribution to ambient PM10 or PM2.5 concentrations outside the site boundary. The ambient air monitoring carried out by OGNZL and WRC of PM10 and respirable silica concentrations (RCS) and combustion emissions from vehicles, at various locations within Waihi and in the vicinity of the mine, has shown that the concentrations of these contaminants are well below the relevant air quality guidelines and NESAQ standard concentration limits. The recent report prepared by NIWA on PM2.5 concentrations in New Zealand also confirms that PM2.5 concentrations in Waihi are likely to be below the proposed annual standard of 10 µg/m3. Maximum 24-hour average PM2.5 concentrations are also not predicted to exceed proposed NESAQ standard of 25 µg/m3 (refer Section 6.3). Background emission sources, including motor vehicles and home heating, are expected to the main contributor to the PM10 and PM2.5 concentrations which occurred at the monitoring sites45. The proposed WNP activities are located in a rural environment where background PM10 and PM2.5 concentrations would be lower than those which occurred at the semi-rural/suburban PM10 monitoring sites. Consequently, the PM10 concentrations observed during the monitoring programme, and the PM2.5 concentrations derived from the PM10 monitoring results, are expected to be higher than these contaminant concentrations which will occur in the vicinity of the WNP. The PM10 and PM2.5 emitted from WNP activities will disperse and dilute as they are transported downwind. All but two sensitive receptors in the vicinity of the WNP are located more than 250 mm from dust generating activities. Therefore, any emitted contaminants from site operation would be expected to be well dispersed before reaching these receptors. The PM10 monitoring has predominantly been undertaken at Site 6.61 (Grey Street) ambient air monitoring site. This monitoring site is located approximately 210 m from the Martha Mine in the predominant downwind direction. Therefore, the measured PM10 concentrations in the vicinity of Martha Mine are expected to provide a conservative indication of the peak concentrations which may occur at dwellings located close to the proposed WNP project. Accordingly, PM10 and PM2.5 concentrations are not expected to exceed the relevant air quality criteria concentrations limits at these dwelling provided appropriate mitigation is implemented and maintained. The closest sensitive receptors to the proposed WNP operations are two rural dwelling located approximately 90 -100 m to the east from the NRS soil stockpile (i.e. dwellings R21 and R22 in Figure 2-1). Generally, only a small proportion of dust generated during the construction of the stockpiles would be expected to be PM10 or PM2.5. Emissions of respirable silica would also be negligible as no rock crushing activity will occur in the vicinity of the dwelling. Therefore, provided the recommended dust mitigation procedures are implement (Section 8.2), any emissions from the operation would not be expected to exceed PM10 or PM2.5 quality criteria limits. 45 This assumption is supported by the TSP monitoring results. At distances of approximately 150 m from Martha Mine, the recorded concentrations are only marginally higher than background TSP concentration. The relative contribution from mine emission sources to PM10 and PM2.5 would be expected to be lower due to the larger particle size distribution of the emitted dust.
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