Vol-1C Chapter-16 Soil-and-water-quality

Previous chapter: Vol 1B Chapter 15 Social and economic

Vol 1C Chapter 16 Soil and water quality

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Section Pages
16 Soil and water quality 16-1
16.1 Assessment methodology 16-2
16.2 Existing environment 16-13
16.3 Assessment of potential impacts 16-33
16.4 Environmental management measures 16-55

Appendix: Vol 2E App N Surface Water

Next chapter: Vol 1C Chapter 17 Contamination

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Vol-1C Chapter-18 Flooding-and-drainage

Previous chapter: Vol 1C Chapter 17 Contamination

Vol 1C Chapter 18 Flooding and drainage

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Section Pages
18 Flooding and drainage 18-1
18.1 Assessment methodology 18-1
18.2 Existing environment 18-3
18.3 Assessment of potential impacts 18-15
18.4 Environmental management measures 18-33

Appendix: Vol 2G App P Flooding

Next chapter: Vol 1C Chapter 19 Groundwater

Vol-1C Chapter-19 Groundwater

Previous chapter: Vol 1C Chapter 18 Flooding and drainage

Vol 1C Chapter 19 Groundwater

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Section Pages
19 Groundwater 19-1
19.1 Assessment methodology 19-1
19.2 Existing environment 19-12
19.3 Assessment of potential impacts 19-31
19.4 Environmental management measures 19-67

Appendix: Vol 2G App Q Groundwater

Next chapter: Vol 1C Chapter 20 Non-Aboriginal heritage

Vol-2G App-P Flooding

Chapter: Vol 1C Chapter 18 Flooding and drainage

Appendix Vol 2G App P Flooding

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Section Pages
  EXECUTIVE SUMMARY 1
1. INTRODUCTION 1
1.1 Overview of WestConnex 1
1.2 Overview of the project 2
1.3 Project location 4
1.4 Secretary’s Environmental Assessment Requirements 4
1.5 Study area 4
1.6 Report structure 5
2. STATUTORY AND POLICY CONTEXT 7
2.1 Relevant Government policies and industry guidelines 7
2.2 Floodplain Development Manual 8
2.3 State Government planning directions and guidelines 8
2.4 State Government floodplain risk management guidelines 9
2.5 Flood related planning controls 11
3. ASSESSMENT METHODOLOGY 15
3.1 Key tasks 15
3.2 Definition of present day flooding behaviour 15
3.3 Sensitivity analyses 16
3.4 Comparison with findings of previous studies 16
3.5 Provisional flood hazard 16
3.6 Impact of the project on flooding behaviour 17
3.7 Impact of flooding on the project 17
3.8 Impact of a partial blockage of major hydraulic structures on flooding behaviour 17
3.9 Impact of future climate change on flooding behaviour 18
4. EXISTING ENVIRONMENT 19
4.1 Catchment description 19
4.1.1 Cooks River 19
4.1.2 Upper Wolli Creek 19
4.1.3 Sheas Creek / Alexandra Canal 19
4.2 Description of existing flood behaviour 19
4.2.1 Upper Wolli Creek floodplain 19
4.2.2 Lower Cooks River floodplain 21
5. FLOOD RISK ASSESSMENT 23
5.1 Overview 23
5.2 Impact of the Project on flood behaviour 23
5.2.1 Upper Wolli Creek floodplain 23
5.2.2 Lower Cooks River floodplain 24
5.3 Impact of flooding on the project 25
5.3.1 Upper Wolli Creek floodplain 25
5.3.2 Lower Cooks River floodplain 26
5.4 Impact of a partial blockage of major hydraulic structures on flood behaviour 26
5.5 Impact of future climate change on flood behaviour 26
5.5.1 Potential increase in rainfall intensities 26
5.5.2 Sea level rise 27
6. ASSESSMENT OF POTENTIAL FLOOD MITIGATION MEASURES 39
6.1 Proposed flood mitigation strategy 39
6.2 General flood mitigation requirements 39
6.3 Upper Wolli Creek floodplain 41
6.3.1 Flooding in existing residential development 41
6.3.2 Flooding in existing commercial/industrial development 41
6.4 Lower Cooks River floodplain 41
6.4.1 Flooding in existing residential development 41
6.4.2 Flooding in existing commercial/industrial development 42
6.4.3 Flooding in TransGrid’s Beaconsfield West Substation 42
7. REFERENCES 43
APPENDIX A. Background to Development of Wolli Creek Flood Models A
APPENDIX B. Background to Development of Lower Cooks River Flood Models B
APPENDIX C. Tables of Peak Flows C

Vol-2G App-Q Groundwater

Chapter: Vol 1C Chapter 19 Groundwater

Appendix Vol 2G App Q Groundwater

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Section Pages
  Executive Summary i
  Glossary of Terms vii
  Acronyms xi
1.0 Introduction 1
1.1 Overview of WestConnex 1
1.2 Overview of the project 2
1.3 Project location 4
1.4 Secretary’s Environmental Assessment Requirements 4
1.5 Study area 5
1.6 Groundwater legislation and policy framework 5
1.7 Report Structure 6
1.8 Limitations 6
2.0 Methodology 7
2.1 Desktop assessment 7
2.1.1 Database searches 7
2.1.2 Review of previous studies 8
2.2 Field investigation 8
2.2.1 Groundwater monitoring network 9
2.3 Groundwater numerical modelling 10
2.3.1 Groundwater model development methodology 10
2.3.2 Assumptions 12
2.3.3 Modelling objectives 12
3.0 Existing Environment 13
3.1 Existing major infrastructure 13
3.2 Rainfall and climate 14
3.3 Topography 14
3.4 Surface water features 14
3.4.1 Cooks River and tributaries 18
3.4.2 Wetlands 18
3.5 Soils 19
3.6 Geological setting 19
3.6.1 Fill Materials 27
3.6.2 Alluvium 27
3.6.3 Botany Sands 27
3.6.4 Palaeochannels 28
3.6.5 Volcanic Intrusions 28
3.6.6 Wianamatta Group 29
3.6.7 Mittagong Formation 29
3.6.8 Hawkesbury Sandstone 29
3.7 Hydrogeological setting 30
3.7.1 Quaternary alluvium 30
3.7.2 Botany Sands Aquifer 30
3.7.3 Ashfield Shale 31
3.7.4 Hawkesbury Sandstone. 31
3.7.5 Structural features 31
3.8 Groundwater Dependent Ecosystems 32
3.9 Existing Groundwater Users 32
3.10 Groundwater inflow in existing Sydney tunnels 41
3.11 Contamination 42
3.11.1 Areas of Known Contamination 42
3.11.2 Areas of Potential Contamination 42
4.0 Field investigations 45
4.1 Existing groundwater levels 45
4.2 Groundwater Quality 46
4.3 Hydraulic conductivity 47
5.0 The project 53
5.1 Project overview 53
5.2 Project features 54
5.2.1 Main tunnel alignment 54
5.2.2 Construction Compounds 55
5.2.3 Tunnel Ventilation System 55
5.2.4 Tunnel lining and groundwater collection system 55
5.3 Geological features along the project corridor 56
5.3.1 Western surface works 56
5.3.2 Main tunnel alignment between western surface works and Southern extension caverns 56
5.3.3 Southern extension cavern 56
5.3.4 Bexley Road surface works 56
5.3.5 Arncliffe motorway operations complex 56
5.3.6 Tunnel between Southern extension cavern and St Peters caverns 57
5.3.7 St Peters caverns 57
5.3.8 M4-M5 Link stub tunnels 57
5.3.9 On and off ramps, St Peters interchange 57
5.3.10 St Peters interchange 57
5.4 Justification for a drained tunnel 58
5.4.1 Undrained Tunnels 58
5.4.2 Why Construct Drained Tunnels 59
5.4.3 Inflow Rate of 1 L/sec/km 59
6.0 Impact assessment – Construction 61
6.1 Potential groundwater inflow 61
6.1.1 Predicted groundwater inflows 62
6.2 Groundwater drawdown impacts 63
6.3 Reduced groundwater recharge impacts 63
6.4 Impacts on existing users 63
6.5 Impacts to the environment 64
6.5.1 Drawdown beneath creeks 64
6.5.2 Groundwater Dependent Ecosystems 64
6.6 Groundwater quality impacts 64
6.6.1 Spills and incidents 65
6.6.2 Intercepting contaminated groundwater 65
6.6.3 Groundwater management 65
6.6.4 Acid Sulfate Soils 66
6.6.5 Groundwater Aggresivity 66
6.7 Alexandria Landfill 67
7.0 Impact assessment – Operational 69
7.1 Potential groundwater inflow 69
7.2 Groundwater drawdown 69
7.3 Groundwater management 75
7.3.1 Alexandria Landfill 75
7.4 Groundwater quality impacts 76
7.5 Impacts to existing users 78
7.6 Impacts to the environment 79
8.0 Mitigation and management measures 85
8.1 Construction 85
8.2 Operation 86
9.0 NSW Aquifer Interference Policy – minimal impact considerations 89
9.1 Aquifer Interference Policy 89
9.2 Minimal impact assessment 89
10.0 Conclusions 93
11.0 References 95
Appendix A Groundwater Modelling Report A
Appendix B Tables B
Appendix C Borehole database search (DPI (Water)) C
Appendix D Hydrographs D
Appendix E Draft groundwater monitoring program E