Wilcannia Weir NSW Department of Premier and Cabinet
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Wilcannia Weir NSW Department of Premier and Cabinet Wilcannia Weir Scoping Study IA064500-NHY-RP-002 | FINAL June 2016 Wilcannia Wei r S copi ng S tu dy NS W Depart men t of P remi er a nd C abine t Wilcannia Weir Scoping Study IA064500 Project No: IA064500 Document Title: Wilcannia Weir Scoping Study Document No.: IA064500-NHY-RP-002 Revision: Final - 03 Date: 21 June 2016 Client Name: NSW Department of Premier and Cabinet Client No: Client Reference Project Manager: Russell Beatty Author: Amy Bentley, Justin Bell File Name: I:\ENVR\Projects\IA064500\Deliverables\Reports\Scoping Study\IA064500_Wilcannia Weir Replacement_Scoping Study_Final_Rev03a.docx Jacobs Group (Australia) Pty Limited ABN 37 001 024 095 100 Christie Street St Leonards NSW 2065 Australia PO Box 164 St Leonards NSW 2065 Australia T +61 2 9928 2100 F +61 2 9928 2500 www.jacobs.com 4 Document history and status Revision Date Description By Review Approved 00 22/01/2016 Draft to Client Amy Bentley Russell Beatty Russell Beatty Justin Bell 01 24/03/2016 Second draft Russell Beatty Brad Woods Russell Beatty 01a 27/04/2016 Minor changes to text Russell Beatty N/A Russell Beatty 02a 15/06/2016 Updated cost estimates and details on existing weir Russell Beatty Brad Woods Russell Beatty repair Chris Dwyer 03 21/06/2016 Final Russell Beatty N/A Russell Beatty IA064500-NHY-RP-002 i Wilcannia Weir Scoping Study Contents Executive Summary .........................................................................................................................................1 1. Introduction ..........................................................................................................................................6 1.1 Background ............................................................................................................................................6 1.2 The Current Studies and Reports ...........................................................................................................6 1.3 Scoping Study Objectives.......................................................................................................................7 1.4 Purpose of the Report ............................................................................................................................7 2. Background ........................................................................................................................................ 10 2.1 Study Area ........................................................................................................................................... 10 2.2 History of Wilcannia ............................................................................................................................. 12 2.4 Weir Ownership ................................................................................................................................... 17 2.5 Previous Studies .................................................................................................................................. 17 2.5.1 SMEC Study (2000) ............................................................................................................................. 18 2.5.2 Public Works Report (2013) ................................................................................................................. 19 2.6 The Potential for Repair of the Existing Weir......................................................................................... 19 3. Water Supply and Demand ................................................................................................................ 21 3.1 Understanding the Current Situation ..................................................................................................... 22 3.1.2 Model Time Study ................................................................................................................................ 28 3.2 Model Outcomes .................................................................................................................................. 28 4. Site Investigations ............................................................................................................................. 30 4.1 Channel Form and Stability Considerations .......................................................................................... 30 4.1.1 Factors Influencing Weir Locations Including Site Constraints............................................................... 31 4.1.2 Fishway Requirements ......................................................................................................................... 32 4.2 Meeting the Local Community .............................................................................................................. 32 4.2.1 Core Theme 1: The value of the river………. ........................................................................................ 32 4.2.2 Core Theme 2: The weir……….. .......................................................................................................... 33 4.2.3 Core Theme 3: A future for Wilcannia…….. .......................................................................................... 33 4.3 Local Heritage ...................................................................................................................................... 33 5. Options Identification and Development........................................................................................... 35 5.1 Options Development ........................................................................................................................... 35 5.1.1 Option 1 – Do nothing .......................................................................................................................... 35 5.1.2 Option 2 – Replacement of the Weir at the Existing Site ....................................................................... 35 5.1.3 Option 3 – Replacement of the Weir at a Downstream Site ................................................................... 36 5.1.4 Final Options ........................................................................................................................................ 36 5.2 Conceptual Layouts ............................................................................................................................. 38 5.3 Preliminary Costings ............................................................................................................................ 39 6. Multi-Criteria Analysis ....................................................................................................................... 41 6.1 Introduction .......................................................................................................................................... 41 6.2 Workshop ............................................................................................................................................ 41 6.3 Results of the Assessment ................................................................................................................... 42 6.4 Key Issues ........................................................................................................................................... 44 IA064500-NHY-RP-002 ii Wilcannia Weir Scoping Study 6.5 Final Outcomes .................................................................................................................................... 44 7. Preferred Weir Option ........................................................................................................................ 45 7.1 Further Conceptual Development ......................................................................................................... 45 7.1.1 Revisiting the Siting of the Downstream Weir ....................................................................................... 45 7.1.2 Weir Functional Specification ............................................................................................................... 48 7.1.3 Flow Gauging ....................................................................................................................................... 49 7.2 More Detailed Costing .......................................................................................................................... 51 8. References ......................................................................................................................................... 54 Appendix A. Outline of Option for Repairing the Existing Weir A.1 Overview A.2 Preliminary Design Recommendations A.3 Preliminary Cost Estimate Appendix B. Hydrologic Assessment B.1 Objective B.2 Model Setup B.2.1 Model Code B.2.2 Model Extent B.2.3 Model Geometry B.2.4 Model Time-Step B.3 Model Boundary Conditions B.3.1 Inflows B.3.2 Outflows B.4 Model Calibration B.4.1 Model Setup B.4.2 Calibration Results B.5 Sensitivity Analysis B.5.1 No Pump between Sandbar1.0 and Wilcannia Weir B.5.2 Exemption for Local Water Utility B.5.3 No Pump between Sandbar1.0 and Wilcannia Weir and Exemption for Local Water Utility B.5.4 Evaporation B.5.5 Local Runoff B.6 Model Prediction B.7 Uncertainty Analysis B.7.1 Exemption for Local Water Utility B.7.2 Additional Pump at Rockbar5.2 and Exemption for Local Water Utility B.7.3 No Pumping and Exemption for Local Water Utility B.8 Summary Appendix C. Model Geometry Appendix D. Costing Details D.1 Preliminary Costings