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Manual of Operational Procedures for Flood Mitigation at Wivenhoe Dam and Somerset Dam 1 the Controlled Version of This Document Is Registered

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Manual of Operational Procedures for Flood Mitigation at Wivenhoe Dam and Somerset Dam 1 the Controlled Version of This Document Is Registered Wivenhoe Dam and Somerset Dam Manual of Operational Procedures for Flood Mitigation Revision 15 | November 2019 15 Revision No. Date Amendment Details 0 27 October 1968 Original issue. 1 6 October 1992 Complete revision and re-issue. 2 13 November 1997 Complete revision and re-issue. 3 24 August 1998 Change to page 23. 4 6 September 2002 Complete revision and re-issue. 5 4 October 2004 Complete revision. 6 20 December 2004 Miscellaneous amendments and re-issue. 7 November 2009 (approved by Gazette notice Complete revision. 22 January 2010) 8 September 2011 Revision but no substantive alteration of objectives, strategies or operating practices. 9 November 2011 Insertion of Section 8 and consequential amendments. 10 October 2012 Revision but no substantive alteration of objectives, strategies or operating practices. 11 November 2013 Revision to take account of changes to the Act and improve clarity, but no substantive alteration of objectives or strategies. Operating practices amended to exclude consideration of Twin Bridges and Savages Crossing following stakeholder input. 12 November 2014 Significant revision including changes from WSDOS investigations, legislative changes and a number of general improvements. 13 November 2015 A number of minor updates to improve readability and application. 14 November 2016 Changes to account for the revised Maximum Flood Storage Level for Somerset Dam and a number of general improvements. 15 November 2019 Revision Revision No: 15 – November 2019 Seqwater Doc No: MAN-0051 Manual of Operational Procedures for Flood Mitigation at Wivenhoe Dam and Somerset Dam 1 The controlled version of this document is registered. All other versions including printed versions are uncontrolled. TABLE OF CONTENTS Table of Contents Glossary ............................................................................................................................................................................. 5 Preface ............................................................................................................................................................................... 9 1. Introduction ................................................................................................................................................................ 10 1.1 Purpose ............................................................................................................................................................ 10 1.2 Application Exclusions ...................................................................................................................................... 10 1.3 Agency Responsibilities ................................................................................................................................... 10 1.4 Legal Authority ................................................................................................................................................. 11 1.5 Document Control ............................................................................................................................................ 11 1.6 Significant Changes in this Revision ................................................................................................................ 11 2. Procedural Matters .................................................................................................................................................... 12 2.1 Operational Arrangements ............................................................................................................................... 12 2.2 Responsibilities of the DSFOE ......................................................................................................................... 12 2.3 Responsibilities of a Duty Flood Operations Engineer ..................................................................................... 13 2.4 Responsibilities of Flood Officers ..................................................................................................................... 13 2.5 Responsibilities of Dam Supervisors ................................................................................................................ 13 2.6 Responsibilities of Dam Operators ................................................................................................................... 13 2.7 Qualifications, Experience and Training of Flood Operations Staff .................................................................. 13 2.8 Maintaining and Improving the FFS.................................................................................................................. 15 2.9 Maintenance of Communications Equipment ................................................................................................... 16 3. Flood Mitigation Objectives ...................................................................................................................................... 17 3.1 Introduction ...................................................................................................................................................... 17 3.2 Flood Mitigation Objectives .............................................................................................................................. 17 3.3 Prevent structural failure of the Dams .............................................................................................................. 17 3.4 Ensure the Dams’ Water Supply Compartments are full at the completion of the Flood Event ........................ 19 3.5 Mitigate Downstream Flooding ......................................................................................................................... 20 3.6 Protect the Environment ................................................................................................................................... 22 4. Flood Operations Overview ...................................................................................................................................... 23 4.1 Introduction ...................................................................................................................................................... 23 4.2 Flood Operations Centre Mobilisation and Demobilisation ............................................................................... 23 4.3 Flood Event Commencement and Ending ........................................................................................................ 23 4.4 Operational Strategy Selection and Release Plan Development ..................................................................... 24 4.5 Use of Rainfall Forecasts ................................................................................................................................. 26 4.6 Consideration of Forecast Rainfall in Flood Operations Centre Mobilisation .................................................... 27 4.7 Consideration of Forecast Rainfall in judging whether Rainfall is Complete or Nearly Complete ..................... 27 4.8 Consideration of Forecast Rainfall in developing a Release Plan .................................................................... 27 4.9 Consideration of Forecast Rainfall in Emergency Response ........................................................................... 29 4.10 Alternative Procedures ..................................................................................................................................... 29 Revision No: 15 – November 2019 Seqwater Doc No: MAN-0051 Manual of Operational Procedures for Flood Mitigation at Wivenhoe Dam and Somerset Dam 2 The controlled version of this document is registered. All other versions including printed versions are uncontrolled. TABLE OF CONTENTS 4.11 Implementing the Release Plan ....................................................................................................................... 30 4.12 Bridge Closure Advice ...................................................................................................................................... 31 4.13 Provision of Data to Agencies .......................................................................................................................... 31 5. Wivenhoe Dam Flood Operations ............................................................................................................................ 32 5.1 Splityard Creek Dam ........................................................................................................................................ 32 5.2 Flood Release Infrastructure ............................................................................................................................ 32 5.3 Flood Mitigation Strategy .................................................................................................................................. 34 5.4 Dam Safety Strategy ........................................................................................................................................ 40 5.5 Drain Down Strategy for Wivenhoe Dam .......................................................................................................... 42 5.6 Modification to Flood Operating Procedures if a Subsequent Flood Event Occurs Prior to the Reconstruction of Triggered Fuse Plugs ......................................................................................................................................
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