Tonkin & Taylor Ltd Wharekirauponga Underground Mine – unplanned detonation air quality assessment Oceana Gold (New Zealand) Limited June 2022 Job No: 1015212.2000 vRev0 Table of contents 1 Introduction 1 1.1 Overview 1 1.2 Purpose and scope 1 1.3 Associated reports 1 2 Environmental setting 2 2.1 Site location 2 2.2 Site surroundings and sensitivity 3 2.3 Existing air quality 5 3 Description of activity and nature of discharges 5 3.1 Description of explosives storage 5 3.2 Nature of discharges 5 3.2.1 Emission scenarios 6 3.3 Discharge location and parameters 8 3.3.1 Stack discharge parameters 8 3.3.2 Emission rates 8 4 Air dispersion modelling approach 9 4.1 Introduction 9 4.2 Modelled receptor locations 9 4.3 Model meteorology 10 4.4 Terrain 10 5 Model results 11 5.1 Introduction 11 5.2 Background concentration 11 5.3 Assessment criteria 11 5.4 Model results 12 5.5 Scaling results for other explosive types 13 5.6 Conservatism in results 14 6 Assessment of effects 16 7 Conclusion 17 8 Applicability 18 Appendix A Gas Dispersal Study Appendix B Emission rate development Appendix C CALMET domain figures Appendix D Contour plots for ANFO detonation
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