| Discharges to Air and Associated Mitigation Methods | Waihi North Project Air Discharge Assessment - Waihi Surface Facilities | 4396626-1331619777-99 | 16/06/2022 | 21 exposed to the wind, keeping surfaces damp and controlling vehicle speeds. To achieve this, OGNZL proposes to use the following dust mitigation methods which are used successfully at the mine at present: ● Limit vehicle speeds on haul roads and access roads within the project area ● Seal the most commonly used access roads ● Minimise haul distances ● Transport rock and ore by conveyor wherever practicable ● Keep roads and construction surfaces damp with water carts and/or fixed sprinklers when required ● Maintain haul roads regularly by grading and laying of fresh rock/gravel ● Utilise, where appropriate and cost effective, approved surface-binding agents for dust control on roads ● Require drivers to use the wheel wash facilities located at main exits to the sites to prevent mud being tracked off site. Speed controls on vehicles have an approximately linear effect on dust emissions17. The Waihi Mine includes a large network of internal roads and accessways that are used by a variety of different types of vehicles ranging from heavy haulage trucks and large earthmoving machinery to cars. OGNZL imposes speed limits within the mine site that are appropriate to the nature of the traffic using the road and the design of the road. The speed limits are imposed for safety and to minimise the generation of dust. The speed limits on routes can change as the mine layout changes over time and specific limits will be included in the AQMP. The number of vehicles used on site is expected to vary during the course of the project. When the project is at peak production, the number of vehicles movements is expected to be comparable to historical levels when Martha Pit and the underground mines were operating. However, higher vehicle movements will occur during the peak construction period (project years 4 and 5) 18. The total vehicle kilometres travelled may increase above current levels due to increased haul distances, e.g. to TSF3 for embankment construction and the locations of the traffic will change. There is, therefore, some potential for the overall discharges of dust generated from vehicle movements to increase. However, the vehicle movements will be spread out over the entire WNP site and providing that the management practices currently employed at the mine continue to be carried out diligently, the scale and effects of the discharges are not expected to increase significantly. Loading, conveying and unloading The loading of material onto trucks and conveyors (and including the subsequent offloading) has the potential to generate dust. Trucks will be loaded with materials from the base of pits and from areas where construction activities are occurring using excavators and loaders. Most of the mined materials will be unloaded onto the main conveyor, stockpiles within the pits or at the Processing Plant, and NRS, or onto areas that are being constructed or rehabilitated. The methods used by OGNZL to control dust from these activities include the following: ● Require machinery operators to minimise drop heights when unloading materials ● Cover or shield conveyors in exposed locations to reduce drying effects and exposure to wind ● Dampen materials to be moved where practicable. Exposed surfaces 17 Supra at 3 18 Stantec Ltd (2022) Waihi North Project Transportation Assessment. Report prepared for Oceana Gold June 2022
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