OceanaGold Waihi North Project Vibration Performance Assessment Page v of 41 Project Number: HP2006-2 Heilig & Partners Save Date: 21/06/2022 5:55:00 PM ABN 56 082 976 714 File Name: WAI-985-000-REP-LC-0018_Rev 0 Table of Contents 1. BACKGROUND............................................................................................................................... 1 2. PROJECT DESCRIPTION .............................................................................................................. 2 2.1. Gladstone Open Pit ................................................................................................................. 2 2.2. Willows Access Tunnel ............................................................................................................ 3 2.3. WUG Access Tunnel ............................................................................................................... 4 2.4. Wharekirauponga Underground Mine (WUG) ......................................................................... 4 3. EFFECTS FROM BLASTING.......................................................................................................... 5 3.1. Factors Influencing the Level of Vibration ............................................................................... 6 3.2. Perceived Effects of Vibration ................................................................................................. 6 4. IMPACT ON NATIVE FROGS......................................................................................................... 7 5. REQUIREMENT FOR VIBRATION LIMITS .................................................................................... 7 6. BLASTING VIBRATION LIMITS...................................................................................................... 8 6.1. Hauraki District Plan ................................................................................................................ 9 6.2. Airblast Overpressure............................................................................................................ 11 6.3. Heritage Structures................................................................................................................ 12 7. TYPE AND SCALE OF BLASTING............................................................................................... 12 7.1. Gladstone Open Pit ............................................................................................................... 13 7.2. WUG Production Blasting...................................................................................................... 13 7.3. Tunnel and Decline Blasting.................................................................................................. 13 8. PROPOSED WNP CONDITIONS ................................................................................................. 14 8.1. Gladstone Open Pit ............................................................................................................... 14 8.2. Willows and Plant Access Tunnels........................................................................................ 15 8.3. Dual Access Tunnels............................................................................................................. 16 8.4. WUG ...................................................................................................................................... 16 8.5. Summary ............................................................................................................................... 16 9. MODELLING VIBRATION............................................................................................................. 17 9.1. Comparison with Previously Predicted Results..................................................................... 19 10. ASSESSMENT APPROACH..................................................................................................... 20 11. RESULTS OF THE VIBRATION ASSESSMENT...................................................................... 20 11.1. Gladstone Open Pit ........................................................................................................... 21 11.2. Willows Access Decline and Development ....................................................................... 21 11.3. WUG Access Tunnel ......................................................................................................... 22 11.4. Wharekirauponga Underground Mine ............................................................................... 22 12. GLADSTONE OVERPRESSURE ASSESSMENT.................................................................... 24 13. TUNNEL OVERPRESSURE ASSESSMENT ........................................................................... 25 13.1. Sources of Overpressure................................................................................................... 25 13.2. Overpressure Levels from Tunnel Blasting ....................................................................... 26 13.3. Other Tunnel Overpressure Controls ................................................................................ 26 14. MITIGATION MEASURES ........................................................................................................ 27 15. VIBRATION MONITORING....................................................................................................... 27 15.1. Access Tunnel Vibration Monitoring.................................................................................. 27 15.1. WUG Vibration Monitoring................................................................................................. 30 16. SUMMARY OF EFFECTS......................................................................................................... 32 APPENDIX A – GOP VIBRATION CONTOURS................................................................................... 34 APPENDIX B – WUG ACCESS DECLINE AND DEVELOPMENT VIBRATION CONTOURS ............ 35 APPENDIX C –PLANT ACCESS TUNNEL VIBRATION CONTOURS................................................. 36 APPENDIX D – WUG PRODUCTION VIBRATION CONTOURS ........................................................ 37 APPENDIX E – GOP OVERPRESSURE MODELLING ....................................................................... 38 APPENDIX F – FAVONA PORTAL BLAST RESULTS......................................................................... 39 APPENDIX G – WUG TUNNEL BLASTING OVERPRESSURE .......................................................... 41
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