Our Ref:9049 13 June 2022 Page 2 File: 9049 Appendix.docx TABLE A3 Estimated Settlements from the Gladstone Open Pit excavation Analysis Average Settlements (mm) GOP Vein Drawdown 36 The average modelled settlements for the depressurisation around the tunnel is 8 mm. The average modelled settlements from potential vein drawdown due to leakage into the tunnel is 85 mm. i.e. ineffective lining or sealing of the tunnel at vein location presents a greater potential for settlement. For the vein drawdown associated with Gladstone Open Pit excavation, the average modelled settlements is 36 mm. The modelling allows estimation of ground surface tilts caused by the additional effects from the tunnel or GOP. They are summarised in Table A4 for the Wharekirauponga Access Tunnel and Table A5 for the Gladstone Open Pit vein dewatering. They have been obtained by selecting the maximum tilt from the surface settlement profiles shown in Figure A2b, A3b and A5. The additional tilt settlements due to the Wharekirauponga Access Tunnel and Gladstone Open Pit vein dewatering effects are very low and indicate the increased potential for damage to structures is low. TABLE A4 Estimation of additional tilts from the Wharekirauponga Access Tunnel Analysis Tilts Depressurisation around Tunnel 1:6400 Vein Dewatering 1:19000 TABLE A5 Estimation of additional tilts from the Gladstone Open Pit vein dewatering Analysis Tilts Vein Dewatering 1:4800 REFERENCES 1. Geoslope International Ltd (2020) ‘Heat and Mass Transfer Modeling with GeoStudio’ 2. Geoslope International Ltd (2020) ‘Stress-Strain Modeling with GeoStudio’ 3. Engineering Geology Ltd (2018) ‘Oceana Gold (New Zealand) Ltd Project Martha Assessment of Ground Settlement’ Ref. 8332. 4. GHD (2021) ‘Waihi North Project – Hydrogeology and Mine Dewatering Report’ Draft.
RkJQdWJsaXNoZXIy MjE2NDg3