| Air Discharges and Associated Mitigation Methods | WNP Wharekirauponga Underground Mine - Assessment of Effects of Discharges to Air | 4397169-66885702-23 | | 32 ● Seal the yard areas surrounding the most trafficked areas ● Use screens and fences if practicable in dust prone areas. 5.2.7 Supply of water for dust suppression As some of the proposed dust mitigation measures depend on the use of water as a dust suppressant, a reliable and sufficient water supply must be available on site. As a general “rule of thumb”, the GPG Dust recommends that an application rate of up to 1 litre/m2/hr may be needed for areas requiring dust control. This application rate does not need to be applied over every square metre of ground for every hour of every day - but sufficient water is required to be available to effectively suppress dust when required. As noted in Section 2.4, water will be supplied to water storage tanks on site for dust suppression and other uses. The proposed water storage will be sufficient for dust suppression as proposed. 5.3 Products of Combustion from Surface Vehicles The operation of diesel or petrol vehicles at the site will generate products of combustion which include particulate matter (PM10, PM2.5,), nitrogen oxides (NOx) and carbon monoxide (CO). The frequency and number of vehicle movements at the site will diminish once the surface infrastructure is completed. The site is relatively remote compared with the Waihi Mine site and it is expected that the effects of emissions from diesel and petrol-powered vehicles will be minimal beyond site boundaries. OGNZL will use electric powered equipment where practicable, which do not produce contaminants from the combustion of fuel. 5.4 Air Discharges from Tunnelling and Mining 5.4.1 Overview The nature of air discharges from tunnelling and mining will be the same as those from other mining activities carried out by OGNZL at the Waihi site. The discharges associated with these activities will be: ● Dust from construction of portals and the ventilation system ● Products of combustion from vehicles and dust from tunnelling and mining that are discharged to air via the ventilation system ● Contaminants from blasting that are discharged to air via the ventilation system. 5.4.2 Dust from construction of portal and ventilation system The construction of the portals and ventilation system has the potential to generate dust from earthworks, loading and unloading of materials and vehicle movements. To control dust, OGNZL will use standard methods used at the Waihi site, including the watering of exposed surfaces and limiting vehicle speeds. 5.4.3 Dust and vehicle emissions from ventilation system Tunnelling and mining will generate dust from excavation, materials handling and vehicle movements, as well as combustion products from vehicles. All underground emissions will be discharged to air via either the portal or the ventilation raises. Therefore, unlike surface activities, discharges generated underground will be exhausted as point sources, rather than as diffuse sources over a larger area. In cool calm conditions emissions from the ventilation raises may be visible as a plume of water vapour. The use of diesel produces the products of combustion including particulates, sulphur dioxide (SO2), NOX and CO. OGNZL proposes to use electric powered equipment, where practicable, which do not produce emissions of combustion related contaminants. Low sulphur diesel is also used
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