Impacts of Underground Coal Mining on Natural Features in the Southern Coalfield Strategic Review
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Impacts of Underground Coal Mining on Natural Features in the Southern Coalfield Strategic Review July 2008 Impacts of underground coal mining on natural features in the Southern Coalfield: strategic review © State of New South Wales through the NSW Department of Planning, 2008 NSW Department of Planning 23-33 Bridge Street Sydney NSW Australia www.planning.nsw.gov.au ISBN 978 0 7347 5901 6 DOP 08_028 Cover photo: A rock bar and small waterfall on Sandy Creek, just downstream of Fire Road 6C, within Dendrobium Area 3 (Source: Sydney Catchment Authority) Disclaimer While every reasonable effort has been made to ensure that this document is correct at the time of publication, the State of New South Wales, its agencies and employees, disclaim any and all liability to any person in respect of anything or the consequences of anything done or omitted to be done in reliance upon the whole or any part of this document. Maps are included in the report to give visual support to the facts and discussion presented within the report. Hence in some instances the extents and boundaries of the mapped features have been displayed at a different scale than the original data acquisition may have intended. This is particularly pertinent for the larger scale maps. The Department of Planning advises that information presented on the maps should be used as a general guide only and not as the sole basis on which property scale management or resource allocation decisions are made. In particular, care should be taken in basing land use, development, or other decisions on mapped data relating to underground coal mine workings. This data set, as displayed, should be seen as indicative, rather than accurate. No such decision should be made without adequate discussions with relevant officers of the Department of Primary Industries in Maitland. The State of New South Wales will not accept responsibility for anything, or the consequences of anything, done or omitted to be done in reliance upon the mapped information. Table of Contents GLOSSARY VI EXECUTIVE SUMMARY 1 1 INTRODUCTION 9 1.1 Context 9 1.2 Terms of Reference 9 1.3 Panel Composition 10 1.4 Panel Process 10 1.4.1 Preliminary Briefings 10 1.4.2 Call for Submissions 11 1.4.3 Public Hearings 11 1.4.4 Field Inspections 11 1.5 Panel Report 12 2 BACKGROUND 14 2.1 Significant Natural Features 14 2.1.2 Watercourses 15 2.1.3 Swamps 16 2.1.4 Groundwater 20 2.1.4.1 Regional Water Table Geometry 22 2.1.5 Flora and Fauna 22 2.2 Cultural Heritage 23 2.3 Human Uses 24 2.3.1 Water Supply Management 24 2.3.1.1 SCA Special Areas 26 2.3.2 Other Human Uses 26 2.3.2.1 Existing Residential and Rural Residential Use 26 2.3.2.2 Proposed Urban Development 26 2.3.2.3 Grazing, Agriculture and Intensive Agricultural Industries 27 2.3.2.4 Wastewater Management 27 2.3.2.5 Conservation Reserves 27 2.3.2.6 Recreational Use 27 2.4 Coal Resources 28 2.4.1 Coal Resource Geology 28 2.4.2 Coal Types and Uses 28 2.4.3 Coal Seam Methane 29 2.5 Coal Mining Operations 29 2.5.1 Historic Mining 29 2.5.2 Current Mining 30 2.5.3 Future Development Potential 30 2.5.4 Underground Coal Mining Systems 32 2.5.4.1 Bord and Pillar Mining 32 2.5.4.2 Pillar Extraction 32 2.5.4.3 Longwall Mining 33 3 SOCIO-ECONOMIC SIGNIFICANCE OF COAL MINING 36 3.1 Economic Significance of the Coal Industry 36 3.1.1 Current Mining 36 3.1.1.1 NSW Coal Production 36 3.1.1.2 Southern Coalfield Production 37 3.1.2 Coal Sector Potential 38 3.1.2.1 Southern Coalfield Potential 38 3.2 Significance to the Local and Regional Economies 39 3.2.1 Income and Expenditure 39 3.2.2 Employment 41 3.3 Income to Government from Mining 43 3.3.1 Royalties 43 3.3.2 Taxes 43 3.4 Social Significance 44 3.5 Other Social and Economic Impacts of Mining 44 i 4 SUBSIDENCE IMPACTS ON NATURAL FEATURES 45 4.1 Subsidence Effects 45 4.1.1 Subsurface Subsidence Effects 45 4.1.2 Conventional Surface Subsidence Effects 47 4.1.3 Non-Conventional Surface Subsidence Effects 52 4.1.3.1 Massive Overburden Strata 52 4.1.3.2 Pillar Foundation Settlement or Failure 53 4.1.3.3 Steep Topography 53 4.1.3.4 Valleys and Gorges 53 4.1.3.5 Regional Far-Field Horizontal Displacement 59 4.1.3.6 Large Scale Geological Features 61 4.2 Subsidence Impacts and Consequences for the Natural Environment 63 4.2.1 Watercourses 63 4.2.1.1 Subsidence Impacts and Consequences at Waratah Rivulet 68 4.2.2 Valleys and Cliff Lines 70 4.2.3 Swamps 72 4.2.4 Groundwater 75 4.2.5 Aquatic Flora and Fauna 75 4.2.6 Aboriginal Heritage 77 4.2.7 Far-Field Subsidence Effects 77 4.3 Prediction of Subsidence Effects, Impacts and Consequences 78 4.3.1 Prediction of Conventional Surface Subsidence Effects 78 4.3.2 Prediction of Non-Conventional Surface Subsidence Effects 80 4.3.3 Prediction of Subsurface Subsidence Effects 81 4.3.4 Prediction of Impacts and Consequences 82 4.3.4.1 Watercourses, Valleys and Cliff Lines 82 4.3.4.2 Swamps 83 4.3.4.3 Groundwater 83 4.3.4.4 Flora and Fauna 84 4.3.4.5 Aboriginal Heritage 84 4.3.4.6 Anomalous Subsidence Impacts 85 4.4 Subsidence Monitoring 85 4.4.1 Monitoring of Subsidence Effects 85 4.4.2 Monitoring of Subsidence Impacts and Consequences 86 4.4.2.1 Watercourses, Valleys and Cliff Lines 86 4.4.2.2 Swamps 87 4.4.2.3 Groundwater 87 4.4.2.4 Flora and Fauna 88 4.4.2.5 Water Quality and Water Supply 89 4.5 Mitigation, Rehabilitation and Remediation 89 4.5.1 Mitigation 90 4.5.2 Rehabilitation 91 4.5.3 Natural Processes of Remediation 93 4.6 Non-Mining Impacts on Significant Natural Features 95 4.6.1 Watercourses 95 4.6.2 Swamps 95 4.6.3 Non-Mining Impacts on Aquatic Ecosystems 97 5 DECISION MAKING AND REGULATORY PROCESSES 98 5.1 Current Regulatory Environment 98 5.1.1 Environmental Planning and Assessment Act 1979 98 5.1.1.1 Historical Background 98 5.1.1.2 Part 3A Approval Regime 99 5.1.1.3 Conditions of Project Approval under Part 3A 99 5.1.2 Mining Act 1992 101 5.1.2.1 Subsidence Management Plans 101 5.1.2.2 Rehabilitation and Security Deposits 101 5.1.3 Stakeholder Consultation 102 5.1.4 Current Review of the SMP Process 102 5.2 Risk-Based Decision Making 103 5.2.1 Rationale for Risk-Based Decision Making 103 5.2.2 Best Practice Risk Management 103 ii 5.2.2.1 Qualitative Risk Assessment 103 5.2.2.2 Choice of Risk Criteria 105 5.2.2.3 Other Key Considerations 106 5.2.3 Nature of Risk Management under the Current Approvals Process 107 5.2.4 Potential New Risk Management Mechanisms 108 5.2.4.1 Proposals for a 1 Kilometre Buffer Zone 108 5.2.4.2 Ecological Risk Based Decision Making 109 5.2.4.3 Net Benefit Based Decision Making 109 5.3 Other Stakeholder Perspectives on Approval Processes 109 5.3.1 Improved Regional Datasets 109 5.3.2 Timing of Applications and Approvals 110 5.3.3 Removal of Duplication 110 5.3.4 Improved Government Guidance to Industry and the Community 110 5.3.5 Early Engagement by Industry with Stakeholders 111 5.4 Potential Improvements to Approvals Processes 111 5.4.1 Relationships between Part 3A Approvals and SMPs 111 5.4.2 Risk Management Zones 111 5.4.3 Improved Guidance on Significance and Value 113 5.4.4 Earlier Engagement with Stakeholders 113 5.4.5 Improved Timeliness of Applications and Approvals 114 5.4.6 Improved Documentation for Environmental Assessments 114 5.4.7 Reverse Onus of Proof and Contingency Planning 114 5.4.8 Increased Monitoring and Back Analysis 115 5.4.9 Increased Security Deposits and Rehabilitation Responsibilities 115 5.4.10 Improved Regional Data Sets 115 6 CONCLUSIONS 116 7 RECOMMENDATIONS 122 8 REFERENCES 125 APPENDIX A: APPLICABLE LEGISLATION 130 A1.1 Environmental Planning and Assessment Act 1979 130 A1.1.1 Historical Background 130 A1.1.2 Part 3A Approval Regime 130 A1.1.3 Conditions of Project Approval under Part 3A 131 A1.2 Mining Act 1992 132 A1.2.1 Statutory Approvals 132 A1.2.2 Mining Operations Plans and Annual Environmental Management Reports 132 A1.2.3 Subsidence Management Plans 133 A1.2.4 Rehabilitation and Security Deposits 135 A1.3 Other Legislation 135 A1.3.1 Sydney Water Catchment Management Act 1998 135 A1.3.2 National Parks and Wildlife Act 1974 137 A1.3.3 Threatened Species Legislation 138 A1.3.3.1 Threatened Species Conservation Act 1995 138 A1.3.3.2 Fisheries Management Act 1994 139 A1.3.4 Dams Safety Act 1978 139 A1.3.5 Other Approvals 140 APPENDIX B: SUBSIDENCE PREDICTION TECHNIQUES 142 B1.1 Empirical Methods 142 B1.2 Analytical – Numerical Methods 143 B1.3 Hybrid Methods 144 APPENDIX C: SUBSURFACE SUBSIDENCE PREDICTION 145 C.1.1 PREDICTION METHODOLOGY 145 C.1.2 PREDICTION ACCURACY 145 APPENDIX D: FLORA AND FAUNA OF THE SOUTHERN COALFIELD 148 D1.1 Terrestrial vegetation 148 D1.2 Terrestrial fauna 149 D1.3 Aquatic flora and fauna 154 D1.3.1 Aquatic Habitats 155 iii D1.3.2 Aquatic Plants 155 D1.3.3 Aquatic Macroinvertebrates 156 D1.3.4 Fish 157 D1.3.5 Significance of Aquatic Flora and Fauna 158 List of Tables Table 1.