B-3 – Area 3 - Assessment of Environmental Effects 18 3. PROJECT DESCRIPTION 3.1 OVERVIEW An underground connection will be provided between the WUG and OGNZL’s main processing area located at the Waihi SFA (Area 5). Specifically, an underground Wharekirauponga Access Tunnel, approximately 5,000 m in length, will be established to connect to the Dual Tunnel within Area 1 to the WUG Portal within Area 5. The Wharekirauponga Access Tunnel will be used to transport ore from underground to the existing Processing Plant, and for general operational access between the mine and the Processing Plant. The Wharekirauponga Access Tunnel will also be used to transport rock from the NRS (Area 6) to the WUG for backfilling of stopes once the supply of rock stored in the Willows Rock Stack (Area 2) is exhausted. 3.2 TUNNEL DESIGN The Wharekirauponga Access Tunnel will be required to facilitate truck access and will be developed with nominal dimensions of 5.8 m (W) x 6.0 m (H). Any lateral development not required to facilitate truck access may be developed with nominal dimensions of between 4.5 – 5.0 m (W) x 4.5 – 7.5 m (H). The tunnel will incorporate communications, electricity, water supply and drainage. In addition to the above generic services and infrastructure, the tunnel will include selfcontained, independently serviced refuge chambers at regular intervals. As described in WSP (2022b) provided in Part H of these application documents, the tunnel is located and designed to prevent surface-level subsidence from occurring. 3.3 TUNNEL CONSTRUCTION METHODOLOGY The Wharekirauponga Access Tunnel will be constructed such that completion coincides with the commencement of mine production. Development will take place from the Waihi SFA and the Willows SFA in parallel, meeting at some point near the middle. This will minimise construction timeframes and enable the tunnel to be built and operated without the need for an additional vent raise. The method of tunnel development will be drilling and blasting using drilling jumbos for face drilling and ground support installation as has been used for other OGNZL underground mines. Load haul dump units (“boggers”) will be used to move fired material away from the face and underground trucks will be used to transport rock to surface stockpiles. The closest stockpiles are the Willows Rock Stack at the northern end and the Polishing Pond stockpile at the southern end.
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