| Project Description | WNP Wharekirauponga Underground Mine - Assessment of Effects of Discharges to Air | 4397169-66885702-23 | | 13 2.2 Key Features of Project in Regard to Air Quality at Willows Road Site 2.2.1 Overview Installation of the following key features of the project may affect surrounding air quality at the Willows Road site for a limited period include: ● Topsoil stripping and storage ● Tunnel portals ● Rock stack (WRS) and clean and dirty water collection ponds ● Site access and haul roads ● Explosive magazines/emulsion storage Tunnel ventilation system and raises ● Noise earth bunds ● Package sewage treatment plant and soakaway area ● Rehabilitation. There will be no surface crushing or other processing of the excavated rock on the Willows Road site. Ore will be transported from the mine to the Processing Plant at Waihi via an underground tunnel (WUG Tunnel). This tunnel will also be used for the transport of rock material back into the mine for backfilling, towards the end of the mine’s life, after stockpiles at Willows Road are empty. 2.2.2 Topsoil stripping and storage Surface infrastructure facilities will be established prior to commencement of tunnelling. The surface footprint areas will first be stripped of topsoil which will be stockpiled in an area to the south of the Poly Farm and used for subsequent works around the site. Transport of this material to storage will likely be by diesel trucks. Areas to be stripped include the Surface Facilities Area, collection pond sites and carpark. Topsoil will be stockpiled in an area of approximately 3ha at no greater than 3m depth. These stockpiles will be stabilised and grassed to prevent erosion and dust generation and to allow return to stock grazing once pasture has been established. 2.2.3 Tunnel portals The portals will form the tunnel entrances. Following further geotechnical investigations to confirm the suitability of the locations, earthworks will be undertaken to form the portals. The works will be undertaken using suitable equipment including a backhoe excavator, bulldozer and rock-breaker. If necessary, blasting will also be used. In respect of the Willows Portal, earthworks and construction tasks to establish the portal will be undertaken and may include a small box cut and/or Armco tunnel arrangement depending on geotechnical conditions. Initially, a single 250 kW ventilation fan will be installed at the entrance to the portal in a shipping container insulated for noise mitigation. This fan will be relocated underground and integrated into the overall tunnel ventilation system on completion of the first vent shaft. All ventilation equipment will be located underground thereafter. Other required equipment and accessories will be installed at the portal, including transformers, water storage tank, lighting, communications, and safety tag board. In respect of the WUG Portal (located at the Waihi Processing Plant), a cut will be made into the hill. The portal will be formed and required services connected prior to commencement of operation. Figure 2-2 shows an example of a tunnel portal.
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