Supporting Technical Assessments

| WNP Processing Plant Air Discharge Assessment | WNP Processing Plant Air Discharge Assessment | 4397169-66885702-113 | 16/06/2022 | i Sensitivity: General Contents 1 Introduction........................................................................................................ 1 1.1 Overview.......................................................................................................................................... 1 1.2 Scope of Report ............................................................................................................................... 1 1.3 Limitations........................................................................................................................................ 1 2 Processing Plant Emissions............................................................................. 3 2.1 Emission Sources ............................................................................................................................ 3 2.2 Mercury Emissions .......................................................................................................................... 3 2.3 Annual Average Mercury Emission Emissions ................................................................................ 4 2.4 Emission of Other Metals................................................................................................................. 7 3 Air Quality Criteria ............................................................................................. 9 3.1 Introduction ...................................................................................................................................... 9 3.2 Assessment Criteria for Mercury ..................................................................................................... 9 3.3 Assessment Criteria for Other Metals............................................................................................ 10 4 Minamata Convention ..................................................................................... 12 4.1 Proposed Changes to NESAQ ...................................................................................................... 12 4.2 Minimata Best Practice Guidelines ................................................................................................ 12 5 Dispersion Modelling Methodology ............................................................... 13 5.1 Overview of the Modelling Methodology........................................................................................ 13 5.4 Modelled Mercury Emission Rates ................................................................................................ 14 5.5 Non-Mercury Metal Emission Scenario and Emission Rates ........................................................ 14 5.6 Modelled Emission Sources .......................................................................................................... 15 5.7 Meteorological Input File................................................................................................................ 15 5.8 Terrain and Receptors ................................................................................................................... 17 5.9 Building Downwash ....................................................................................................................... 18 5.10 Other Dispersion Modelling Parameters........................................................................................ 19 5.11 99.9 Percentile 1-hour Average Concentrations ........................................................................... 19 6 Dispersion Model Predictions ........................................................................ 20 6.1 Predicted Annual Average Mercury Concentrations ..................................................................... 20 6.2 Predicted Concentrations for Other Metals ................................................................................... 20 7 Summary and Recommendation.................................................................... 22 7.1 Summary of Assessment ............................................................................................................... 22 7.2 Recommendations ......................................................................................................................... 22 Appendices Appendix A – Summary of Ore Processing

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