Vol-2G App-Q Groundwater

Chapter: Vol 1C Chapter 19 Groundwater

Appendix Vol 2G App Q Groundwater

Hi-res pdf: New M5 EIS Vol 2G App Q Groundwater.pdf

Low-res pdfs:

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
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