NAMOI CATCHMENT WATER STUDY INDEPENDENT EXPERT FINAL STUDY REPORT July 2012 50371/P4-R2 FINAL Prepared for: Department of Trade and Investment, Regional Infrastructure and Services, New South Wales, (DTIRIS NSW) Locked Bag 21 Orange NSW 2800 Australia Prepared by: Schlumberger Water Services (Australia) Pty Ltd Level 5, 256 St Georges Terrace Perth WA 6000 Australia 50371/P4-R2 FINAL Schlumberger Water Services DTIRIS (NSW) THIS PAGE HAS BEEN LEFT BLANK INTENTIONALLY 50371/P4-R2 FINAL Schlumberger Water Services DTIRIS (NSW) REPORT REVIEW SHEET NAMOI CATCHMENT WATER STUDY INDEPENDENT EXPERT FINAL STUDY REPORT Report no: 50371/P4-R2 FINAL Client name: DTIRIS (NSW) Client contact: Mr. Mal Peters, Chairman, Ministerial Oversight Committee (MOC) SWS Project Manager: Sean Murphy SWS Technical Reviewer: Mark Anderson Main Authors: Gareth Price, Laura Bellis Date Issue No Revision SWS Approval 4/05/2012 1 Draft Mark Anderson 29/06/2012 2 Interim Final Mark Anderson 27/07/2012 3 Final Mark Anderson 50371/P4-R2 FINAL Schlumberger Water Services DTIRIS (NSW) THIS PAGE HAS BEEN LEFT BLANK INTENTIONALLY 50371/P4-R2 FINAL Schlumberger Water Services DTIRIS (NSW) CONTENTS Page EXECUTIVE SUMMARY I 1 INTRODUCTION 1 1.2 Study requirements 2 1.4 Summary 5 2 CONCEPTUALISATION 7 2.1 Introduction 7 2.2 Geology 7 2.2.1 Regional geology 7 2.2.2 Geological model 9 2.3 Hydrology 11 2.3.1 Introduction 11 2.3.2 Catchment setting and surface water features 11 2.3.3 Surface water levels and flow 12 2.3.4 Surface water abstraction 13 2.4.1 Introduction 13 2.4.2 Recharge 13 2.4.3 Groundwater levels and flow 15 2.4.4 Groundwater surface water interactions 17 2.4.5 Aquifer properties 18 2.4.6 Groundwater quality 21 2.4.7 Groundwater management and abstraction 22 3 COAL AND COAL SEAM GAS RESOURCES 23 3.3 Coal seam gas 25 3.4 Potential impacts of coal and CSG development on water resources 27 3.4.1 Spatial relationship to water resources 27 3.4.2 Potential impacts of coal mining 27 3.4.3 Potential impacts of CSG extraction 28 4 NUMERICAL MODELLING 31 4.1 Introduction 31 4.2 Model requirements 32 4.3 Model rationale 33 4.4 Modelling extent and scale 34 4.5 Simulation of water quality 36 4.5.1 Groundwater quality 36 4.5.2 Surface water quality 38 4.6 Simulation of hydraulic fracturing (fracking) 39 50371/P4-R2 FINAL Schlumberger Water Services DTIRIS (NSW) Contents 4.7 Model development 39 4.7.1 Hydrologic model 39 4.7.2 Groundwater model 41 4.8 Model operation 43 4.8.1 Introduction 43 4.8.2 Calibration 43 4.8.3 Predictive scenarios 45 4.8.4 Sensitivity and uncertainty 48 4.9 Model assumptions 49 5 ASSESSMENT OF POTENTIAL IMPACTS 53 5.1 Introduction 53 5.2 Proximity 54 5.3 Surface water 55 5.3.1 Introduction 55 5.3.2 Rainfall runoff 56 5.3.3 Surface water / groundwater interaction 59 5.4 Groundwater 61 5.5 Catchment water availability 72 6 MONITORING PROGRAM 75 6.1 Introduction 75 6.2.1 Introduction 75 6.2.2 Climate 75 6.2.3 Surface water 76 6.2.4 Groundwater 77 6.3 Further works and investigations 83 6.3.1 Introduction 83 6.3.2 Groundwater Model 83 6.3.3 Hydrologic Model 90 6.4 Summary of recommendations 92 7 IMPACT MITIGATION AND MANAGEMENT 95 7.1 Introduction 95 7.3 Risk reduction 96 REFERENCES 105 50371/P4-R2 FINAL Schlumberger Water Services DTIRIS (NSW) Contents TABLES After page Table E1 Scenario configuration iii Table E2 Risk of impacts to groundwater levels and confidence in predictions v Table E3 Higher priority investigation and monitoring recommendations vii Table 2.1 Summary stratigraphic table 8 Table 2.2 Geological model layers 11 Table 2.3 Recharge summary table 14 Table 2.4 Hydraulic parameters 20 Table 2.5 Mean groundwater quality values for the Gunnedah Basin (Santos) 21 Table 2.6 Groundwater abstractions 22 Table 3.1 Coal seams within the Maules Creek Formation 24 Table 3.2 Eastern Star Gas pilot sites 26 Table 4.1 Local vs. regional models 34 Table 4.2 Scenario configuration 46 Table 5.1 Proximity of coal bearing formations to Namoi catchment groundwater resource 54 Table 5.2 Average flow change 2010 to 2100 (% change from Scenario 0) 56 Table 5.3 Flow changes from sensitivity analysis (as % of Scenario 0) 57 Table 5.4 Surface water flow sites chosen for uncertainty analysis 58 Table 5.5 Summary of surface water / groundwater interactions for Scenario 3 60 Table 5.6 Flow statistics and Scenario 3 impacts for the Namoi River at Narrabri 61 Table 5.7 Source of groundwater level impacts 64 Table 5.8 Maximum average drawdown (m) predicted in the Upper and Lower Namoi Alluvium Management Zones in the sensitivity analysis 66 Table 5.9 Model predictive uncertainty 68 Table 5.10 A qualitative assessment of predictive confidence 69 Table 5.11 A qualitative assessment of predictive confidence 71 Table 6.1 Rainfall stations used in the Hydrologic Model 76 Table 6.2 Surface water gauging stations 77 Table 6.3 Alluvial monitoring bores used in the calibration dataset 78 Table 6.4 Existing short record alluvial monitoring bores that can be used to supplement the calibration dataset 80 Table 6.5 Non-alluvial aquifer monitoring bores used in the calibration dataset 80 Table 6.6 Mine related monitoring used in the calibration dataset 81 Table 6.7 Surface water gauging stations used to set boundary conditions in the Groundwater Model 82 Table 6.8 Summary of monitoring recommendations 93 Table 7.1 Potential mitigation options for different impacts 103 FIGURES After page E1 Water resources of the Namoi catchment x E2 Proximity between alluvial and fractured rock aquifer groundwater resources and potential coal and gas resources x E3 Mining and coal seam gas activities simulated in the long term development scenario (Scenario 3) x E4 Long term predicted maximum impacts on groundwater levels (Scenario 1) x E5 Long term predicted maximum impacts on groundwater levels (Scenario 2) x E6 Long term predicted maximum impacts on groundwater levels (Scenario 3) x E7 Potential risk to groundwater resource (quantity) x E8 Assessment of confidence in predicted groundwater impacts x E9 Long term predicted maximum impacts on groundwater levels (Scenario 6) x E10 Predicted impacts on water availability from coal and gas developments compared to non-coal related activities (Scenario 3) x 1.1 Namoi catchment location map 6 50371/P4-R2 FINAL Schlumberger Water Services DTIRIS (NSW) Contents 1.2 Namoi river catchment 6 1.3 Significant alluvial units 6 2.1 Namoi catchment regional geology 22 2.2 Representative geological cross section 22 2.3 The "SeeBase" (SRK, 2011) Digital Surface (used to define the base of Permian/top of Boggabri Volcanics) 22 2.4 Topography of the Namoi catchment 22 2.5 Surface water catchments 22 2.6 Annual average rainfall distribution 22 2.7 Surface water network and infrastructure 22 2.8 Namoi River flow at Gunnedah 22 2.9 Surface water licence locations and sub-catchment areas 22 2.10 Surface water abstractions from each sub-catchment 22 2.11 Schematic of recharge processes 22 2.12 Irrigation and floodplain areas 22 2.13 Time variant groundwater level monitoring sites 22 2.14 Example groundwater level hydrographs 22 2.15 Artesian groundwater heads in selected Great Artesian Basin bores 22 2.16 Catchment wide water level contour map 22 2.17a Non-alluvial groundwater contours (1985) 22 2.17b Narrabri Formation groundwater contours (1985) 22 2.17c Gunnedah Formation and Lower Namoi Alluvium groundwater contours (1985) 22 2.18 Mapping of stream/aquifer connectivity (Ivokovic, 2006) 22 2.19 Depth to water table within the Upper Namoi Alluvium 22 2.20 Salinity records from the Pinneena database 22 2.21 Groundwater licence locations 22 2.22 Groundwater abstraction volumes 22 3.1 Location of coal mining development and exploration areas in the Namoi catchment 30 3.2 Details of coal mining development and exploration within the Namoi catchment 30 3.3 Location of Petroleum Licences in the Namoi catchment 30 3.4 Location of Petroleum Licences and pilot well groups 30 3.5 CSG projected water production curves 30 3.6 Interpreted depth to coal bearing formations and relationship to water resources 30 3.7 Conceptual impact pathway for coal mining activities on Namoi catchment water resources (1) 30 3.8 Conceptual impact pathway for coal mining activities on Namoi catchment water resources (2) 30 3.9 Conceptual impact pathway for coal seam gas activities on Namoi catchment water resources 30 4.1 Sub-catchments with LASCAM identifiers 52 4.2 Hillslope schematic cross section 52 4.3 Schematic of LASCAM hillslope idealisation, the four water stores, and the dominant fluxes 52 4.4 Surface water gauging stations and storages 52 4.5a Predicted vs observed annual flows for selected stations, 1990-2010 (1) 52 4.5b Predicted vs observed annual flows for selected stations, 1990-2010 (2) 52 4.6 Predicted monthly average recharge and evaporation for selected catchments 52 4.7 Domain and extent of Groundwater Model 52 4.8 Groundwater Model cross section (Column 75) 52 4.9 Groundwater Model no flow boundaries 52 4.10 Groundwater Model locations of simulated background groundwater abstraction 52 4.11 Groundwater Model locations of river boundary conditions 52 4.12 Mining and coal seam gas activities simulated in Scenario 1 52 4.13 Mining and coal seam gas activities simulated in Scenario 2 52 4.14 Mining and coal seam gas activities simulated in Scenario 3 52 4.15 Mining and coal seam gas activities simulated in Scenario 4 52 4.16 Mining and coal seam gas activities simulated in Scenario 5 52 50371/P4-R2 FINAL Schlumberger Water Services DTIRIS (NSW) Contents 4.17 Mining and