B-1 - Area 1, Coromandel Forest Park – Assessment of Environmental Effects 41 3.2.2.4 Water Management Water encountered during tunnel construction or mining operations wil l be drained to sumps. Water not recycled for drilling purposes will be pumped via the mine services to the WTP for treatment and discharge. Engineering controls, including sealing and grouting tunnels and shafts during development with grout or shotcrete, may be required to manage water ingress that has the potential to affect surface waters. 3.2.3 Vent Shafts 3.2.3.1 Vent Shaft Site Selection Vent Shafts 2 – 5 will be located above the Wharekirauponga orebody on HDC paper road that traverses the CFP. Potential shaft locations will be determined by ecological surveys, to minimise impacts on flora and fauna. Boffa Miskell (2022b) sets out the specific criteria for determining a vent shaft site to be ecologically suitable. They are as per the conditions on the existing Access Arrangement for locating drill sites. Following the determination of ecological suitability, geotechnical assessment is required to confirm suitability of the site for a vent shaft. Geotechnical investigations at each shaft site will require the clearance of approximately 12 m x 12 m of vegetation within SNA T13P152.5 Following the clearance of vegetation, a temporary drilling pad will be constructed, and a drilling rig imported by helicopter.6 Figures 22, 23 and 24 provide an overview of the construction set up and operation of the drill sites. When investigative drilling at the site is completed, an assessment of the suitability of the site for a vent shaft will be undertaken. Should the location be declared unsuitable, or significant mineralisation be discovered, an alternative drill site will be established, and the process repeated, including further ecological surveys. A maximum of four vent shaft sites will be cleared. The tunnel design (including location) will be finalised on identification of suitable vent shaft sites, however, the ability to construct vent shafts at an angle or develop drives to intersect these shafts to connect with the tunnel system means that it is unlikely that the alignment of the Dual Tunnel will need to change for this purpose. All works will be serviced via helicopter staged from either the Waihi SFA (Area 5) or the former Golden Cross mine. Typically, this would involve up to ten flights per week, for 5 Note this SNA has an overall footprint of approximately 7185 ha. 6 The OGNZL exploration team currently utilises Eurocopter A350 “Squirrel” helicopters with a maximum lifting capacity of 1250kg.
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