EGL Ref: 9049 23 June 2022 Page iv File: WAI-985-000-REP-LC-0050-Rev0.docx This report shall only be read in its entirety. Response Plan. Additional settlement and groundwater monitoring is required in this area. o The Wharekirauponga Access Tunnel decline (Figure 3) length, starting from the WUG Portal and extending north past Barry Road, potentially comes close to the younger volcanics. It could cause settlement effects affecting dwellings at Boyd Road and at the eastern end of Barry Road, if the potential for dewatering of the younger volcanics is not mitigated (See Section 6.1.3). OGNZL owns the land between Boyd Road and the proposed tunnel corridor and the land within the tunnel corridor immediately north and south of Barry Road. There are mitigation options available that OGNZL will implement in response to groundwater drawdown or settlement of the younger volcanics as part of a specific Trigger Action Response Plan. Additional settlement and groundwater monitoring is required in this area. o The additional settlements from the Wharekirauponga Access Tunnel east of Waihi East (Figure 2) are expected to be in the order of 10 to 100 mm, depending on the geological structures it passes through. The tunnel east of Waihi East is to be located at depth in andesite rock and the shallow water table in the younger volcanics is not expected to be materially affected. Therefore, any additional tilts in this area will be very small (see Section 6.1.4) and the residential dwellings in this area will not be damaged. Additional settlement and groundwater monitoring is required in this area to confirm settlement effects are as expected. o The settlements from the Willows Access Tunnel and Wharekirauponga Dual Tunnel (Figure 1) out to WUG are expected to be in the order of 10 to 100 mm depending on the geological structures. The tunnel is to be located at depth in andesite rock. There are no structures near to the Willows Access Tunnel and Wharekirauponga Dual Tunnel which could be affected (see Section 6.1.5). o Settlements around the ventilation shafts (Figure 1) are expected to be on the order of 50 to 300 mm. These settlements would have no adverse effects on the farmland (Willows Ventilation Shaft) and forest area (WUG Ventilation Shafts) in which they would be located (see Section 6.1.6). o Ground settlements at the WUG site (Figure 1) are expected to be unnoticeable as any change in level will occur gradually over hundreds of metres resulting in small tilts or change in grade. This is because the settlement will be caused by dewatering generally at notable depth below the ground surface. In the middle of the settlement area, the settlements are estimated to reach up to 300 mm to 1,000 mm depending on the ground profile. Due to the hilly terrain at the WUG site, surface settlements of this magnitude are not expected to have any material effects on stream flows as the change in grade is notably less than the steepness of the terrain. As the tilt of the ground will be small, no noticeable impact on the forest environment is expected (see Section 6.1.7).
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