Somerset Dam Emergency Action Plan
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SOMERSET DAM EMERGENCY ACTION PLAN Expires: March 2021 Somerset Dam Emergency Action Plan QUICK REFERENCE GUIDE Emergency Condition Level Dam Hazard Alert Lean Forward Stand Up Stand Down Flood Event (Section Reservoir Level within 1 metre Reservoir Level within 1 metre Radial gates or Sluice Gates Reservoir Level below Full 7.1) of Full Supply Level* and of Full Supply Level* and fail to operate properly during Supply Level*. Possible Flood Event Likely Flood Event Declaration a declared flood event or; Declaration from the Flood from the Flood Operations Reservoir Level greater than Operations Centre. Centre. Full Supply Level*. Activate Wivenhoe Dam EAP and determine if a cascade failure of Wivenhoe Dam is feasible. Significant Increase in Earthquake of Magnitude 3 or Seepage is increasing or earth Dam failure is considered Seepage through the Dam is Seepage or New Area of higher detected in the vicinity material evident in the possible via an identified controlled and; Seepage (Section 7.2) of the Dam or; seepage is increasing and; failure mechanism. No indicators of potential Dam Significant new or increased The increases cannot be Activate Wivenhoe Dam EAP failure are present. seepage areas identified at controlled. and determine if a cascade the Dam or; failure of Wivenhoe Dam is feasible. Seepage areas containing earth material identified at the Dam. Rev. no. Doc No. Doc Owner Version Date Doc Approver 10.1 ERP-00045 Principal Engineer, Dam Safety 31/03/2021 Manager Technical Support and Improvement Page 2 of 77 Operations The controlled version of this document is registered. All other versions are uncontrolled. Somerset Dam Emergency Action Plan Structural Damage to Earthquake of Magnitude 3 or A Terrorist Threat or Incident New structural damage or Dam embankment is stable Dam (Section 7.3) higher detected in the vicinity is reported at the Dam Site or; movement areas indicate and; of the Dam or; some potential for a structural New structural damage or No potential indicators of failure of the Dam. New structural damage or movement areas have not potential Dam failure are movement areas identified at stabilised and are Activate Wivenhoe Dam EAP present. the Dam. demonstrating indications of and determine if a cascade continued worsening. failure of Wivenhoe Dam is feasible. *The Full Supply Level of Somerset Dam can be altered by Government Regulation to reduce flooding risks. Rev. no. Doc No. Doc Owner Version Date Doc Approver 10.1 ERP-00045 Principal Engineer, Dam Safety 31/03/2021 Manager Technical Support and Improvement Page 3 of 77 Operations The controlled version of this document is registered. All other versions are uncontrolled. Somerset Dam Emergency Action Plan DISTRIBUTION CONTROL SHEET (Controlled Hard Copies) Agency Position Location Seqwater Storage Supervisor Somerset Dam Flood Operations Seqwater Principal Engineer Dam Safety Centre, Brisbane Flood Operations Seqwater Principal Engineer Dam Safety Centre, Ipswich Department of Regional Development, Director of Dam Safety Brisbane Manufacturing and Water Queensland Fire and Duty Officer Brisbane Emergency Services Brisbane City Council Local Disaster Coordinator Brisbane Somerset Regional Local Disaster Coordinator Esk Council Ipswich City Council Local Disaster Coordinator Ipswich Executive Officer, Ipswich Queensland Police District Disaster Management Ipswich Service Group Executive Officer, Brisbane Queensland Police District Disaster Management Brisbane Service Group Rev. no. Doc No. Doc Owner Version Date Doc Approver 10.1 ERP-00045 Principal 31/03/2021 Manager Technical Support Page 4 of 77 Engineer, Dam and Improvement Safety Operations The controlled version of this document is registered. All other versions are uncontrolled. Somerset Dam Emergency Action Plan Revision Status Rev No. Date Revision Description 0 October 2008 Original 1 August 2009 Revision 1 2 September 2010 Revision 2 2.1 June 2011 Contact register updated 3 September 2011 Revision 3 4 August 2012 Revision 4 5 November 2013 Revised and updated in accordance with new guidelines from the Department of Regional Development, Manufacturing and Water 6 October 2014 Revised following discussions with the Department of Regional Development, Manufacturing and Water and other stakeholders 7 August 2015 Revision 7 8 August 2016 Revision 8 9 June 2018 Revision 9 9.1 September 2019 Annual review and non-substantive amendments made. 9.2 September 2020 Annual review and non-substantive amendments made. 10 February 2021 Revision 10 revised layout 10.1 March 2021 Non-substantive amendments made based on feedback from disaster management agencies. Rev. no. Doc No. Doc Owner Version Date Doc Approver 10.1 ERP-00045 Principal 31/03/2021 Manager Technical Support Page 5 of 77 Engineer, Dam and Improvement Safety Operations The controlled version of this document is registered. All other versions are uncontrolled. Somerset Dam Emergency Action Plan TABLE OF CONTENTS Quick Reference guide ..................................................................................... 2 1 INTRODUCTION ...................................................................................... 9 2 ROLES AND RESPONSIBILITIES ........................................................ 10 3 NOTIFICATION DETAILS ..................................................................... 12 3.1 Content of Notification Messages ........................................................... 19 4 BASIC DETAILS OF THE DAM ............................................................. 21 5 EMERGENCY EVENTS AND ACTION LIST ......................................... 23 5.1 Flood Event ............................................................................................ 24 5.2 Significant Increase in Seepage or New Area of Seepage ..................... 29 5.3 Structural Damage to Dam ..................................................................... 32 5.4 Potential Indicators of Structural Damage to the Dam ............................ 35 6 DAM FAILURE HAZARD INUNDATION MAPS .................................... 37 7 DOWNSTREAM RELEASE HAZARD MAPS AND INFORMATION ..... 41 APPENDIX A – Contact Register ................................................................... 43 APPENDIX B - Dam Safety Emergency – Assistance To Site ..................... 46 APPENDIX C - General Arrangement Plans .................................................. 48 APPENDIX D – Identified Structural Failure Modes ..................................... 51 APPENDIX E – Area Map and Site Access Arrangements ........................... 53 APPENDIX F – Drawings of the Storage Catchment Area ........................... 55 APPENDIX G - Storage and Discharge Curves ............................................. 57 APPENDIX H – Seqwater Dam Safety Management Information ................ 60 APPENDIX I – Notification Arrangements ..................................................... 66 APPENDIX J – Emergency Alert Polygon ..................................................... 75 Rev. no. Doc No. Doc Owner Version Date Doc Approver 10.1 ERP-00045 Principal 31/03/2021 Manager Technical Support Page 6 of 77 Engineer, Dam and Improvement Safety Operations The controlled version of this document is registered. All other versions are uncontrolled. Somerset Dam Emergency Action Plan ABBREVIATIONS AEP Annual Exceedance Probability AHD Australian Height Datum ANCOLD Australian National Committee on Large Dams BoM Bureau of Meteorology DDMG District Disaster Management Group DRDMW Department of Regional Development, Manufacturing and Water EAP Emergency Action Plan ERP Emergency Response Plan FSL Full Supply Level FOC Flood Operations Centre, Seqwater LDC Local Disaster Coordinator LDMG Local Disaster Management Group LGA Local Government Area ML Megalitre PAR Population At Risk PMF Probable Maximum Flood PMP Probable Maximum Precipitation PMPDF Probable Maximum Precipitation Design Flood QFES Queensland Fire and Emergency Services SDCC State Disaster Coordination Centre Rev. no. Doc No. Doc Owner Version Date Doc Approver 10.1 ERP-00045 Principal 31/03/2021 Manager Technical Support Page 7 of 77 Engineer, Dam and Improvement Safety Operations The controlled version of this document is registered. All other versions are uncontrolled. Somerset Dam Emergency Action Plan DEFINITIONS For the purposes of this document: • Dam Hazards as defined by the Water Supply (Safety and Reliability) Act 2008 include both Downstream Release Hazards and Dam Failure Hazards. • A Downstream Release Hazard is associated with natural flooding and a release of water from the Dam caused by water that has flowed naturally into the Dam, filling it and making the Dam overflow. A Downstream Release Hazard is not associated with a potential failure of the Dam Structure. • A Dam Failure Hazard is associated with an uncontrolled release of water from the Dam caused by a failure of the Dam Structure. A Dam Failure Hazard could occur either during a period of natural flooding or when no natural flooding is occurring (Sunny Day Failure). If a Dam Failure Hazard occurs during a period of natural flooding, the flood impacts downstream of the dam cause by the Dam failure will be worsened by the natural flooding. • A Sunny Day Failure of the Dam is a failure of the Dam Structure that occurs when no natural flooding is occurring. • Emergency Events as defined by the Water Supply (Safety and Reliability) Act 2008 includes any Downstream Release Hazard Event or Dam Safety Emergency Event