| Potential Effects of Project on Environment | WNP Wharekirauponga Underground Mine - Assessment of Effects of Discharges to Air | 4397169-66885702-23 | | 46 travel. The ventilation raises will be sited significantly further away and will present negligible effect on dwellings. Winds from the northwest are generally light and will rarely exceed 5m/s. While some earthworks will occur at these sites, the volumes are relatively small and the duration relatively short. During operation, small amounts of dust may be emitted from these locations. It is recommended that OGNZL use the control methods described in Section 5 to minimise the generation of dust both during construction and operation. The low volumes of dust and the significant separation distance to the nearest privately owned dwelling means that the risk of dust creating adverse effects from these point sources is negligible. 7.7 Potential Health Effects 7.7.1 Overview The construction and operations at Willows Road will involve the use of motor vehicles and machinery which generate products of combustion including PM10, PM2.5, NOx and CO. Blasting emissions from the development of the tunnel portal, and operation of the mine, will also generate contaminants such as particulates. Respirable silica can be present in dust generated by mineral extraction activities which can cause adverse health effects. Fine particles of crystalline silica contained in dust (<10 µm) are able to be inhaled into the lungs and cause significant health effects (silicosis) if people are exposed above recommended guideline levels over extended periods of time. Most of the particulate matter generated from the proposed operation will be of a larger-size fractions rather than PM10 or PM2.5. Emissions from dust generation are therefore expected to make only a relatively small contribution to ambient PM10 or PM2.5 concentrations outside the site boundary. The recent report prepared by NIWA on PM2.5 concentrations in New Zealand26 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. 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 sites27. The proposed 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. 7.7.2 Results of ambient air quality monitoring The ambient air monitoring carried out by OGNZL and WRC of PM10 and respirable silica concentrations and combustion emissions from vehicles at various locations within Waihi and in the vicinity of the Waihi mine has shown that these contaminants are well below relevant guideline and standard concentration limits. 26 NIWA (2019) PM2.5 in New Zealand- Modelling the current (2018) levels of fine particulate air pollution; report prepared for the Ministry for Environment (December 2019) 27 This assumption is supported by the TSP monitoring results. At distances of approximately 150m 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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