| Potential Effects on the Environment of WNP | Waihi North Project Air Discharge Assessment - Waihi Surface Facilities | 4396626-1331619777-99 | 16/06/2022 | 62 Therefore, it is considered that the discharges to air of PM10, PM2.5 and respirable silica from the proposed activities can be adequately avoided and mitigated and the risk of adverse health effects occurring will be negligible. 7.6 Potential Vegetation Effects Excessive dust has the potential to adversely affect vegetation by interfering with plant photosynthesis, promoting weed or disease incidence and impacting on the application of pesticides or fertilisers. Excessive dust can also make pasture unpalatable to stock. The nature and degree of effects of dust deposition on plants is dependent on the chemical characteristics of the dust, the particle size of the dust and the species of plant. Unfortunately, there is very little quantitative information available on the levels of dust deposition that may lead to adverse effects on vegetation. The nature of the vegetation that is present around the boundaries of the WNP areas is predominantly pasture with some areas of native bush such as the Ngati Koi Reserve and a bush-clad hill located to the north-east of the NRS. There is an area to the south of TSF1A on which kiwifruit is cultivated. However, this area is located more than 900 m from the proposed activities and would not be expected to be impacted by emissions from the WNP. There has been no damage to vegetation reported as a result of the current mining activity. As dust emissions from the WNP are not expected to result in any significant increase in dust concentrations, adverse effects on vegetation are also not expected to occur. The area has a relatively high rainfall and any dust collected on the vegetation will be regularly washed off in rain events. Providing the proposed mitigation measures are carried out as described, the risk of any significant adverse effects on vegetation resulting from discharges of dust from the WNP is considered to be low. 7.7 Processing Plant 7.7.1 Assessment of Processing Plant - , Crusher and Materials Handling discharges Although emissions from the Processing Plant would be expected to increase in response to the projected increase in ore processing rates the proposed changes would not be expected to result in any substantial change to the nature of the discharges to air from the processes. The primary discharges to air from the Processing Plant (excluding smelting operating) is particulate matter generated from the crusher and mill operation. Separation distances published by the Environment Protection Agency Victoria (Vic EPA)46 are widely used in New Zealand as an initial screening method to assess if discharges may have an adverse effect and whether a further, more detailed assessment may be required. The Vic EPA recommends a separation distance of 250 m for mining operation involving the crushing, screening, stockpiling and conveying of minerals. The closest private dwelling is located more than 600 m to the northwest of the Processing Plant, or 2.4 times the recommended Vic EPA separation distance. Therefore, any emissions from the plant would be expected to be well dispersed and diluted before reaching these receptors and highly unlikely to have any adverse effects. The wind flows measured at the Barry Road monitoring station (Site 6.63 Met Station) also indicate that these dwellings would only be infrequently downwind of the Processing Plant (approximately 6.7% of the time (refer Figure 5-3)) and therefore rarely exposed to emissions from the plant. 46 Recommended Separation Distances for Industrial Residual Air Emissions. Victoria EPA, March 2013.
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