BROWN HILL KESWICK CREEK CATCHMENT STORMWATER MANAGEMENT PLAN 2016 MARCH 2016 THE CITIES OF ADELAIDE, BURNSIDE, MITCHAM, UNLEY AND WEST TORRENS Electronic files in PDF format: Main document (including figures): file name bhkc20160311d – smp+figures Appendices: file name bhkc20160311d – appendices Main document (including figures) with appendices: file name bhkc20160311d www.bhkcstormwater.com.au Endorsed: BHKC project Steering Group 11 March 2016 File: bhkc20160311d – smp+figures Cover Photo: Ridge Park flood control dam – biofiltration basin and water injection and extraction bore housing for the managed aquifer recharge facility CONTENTS LIST OF FIGURES .................................................................................................................................... IX LIST OF TABLES ....................................................................................................................................... X ABBREVIATIONS .................................................................................................................................... XIV REFERENCE TO STREETS AND ROADS ............................................................................................ XVI ACKNOWLEDGEMENTS....................................................................................................................... XVII EXECUTIVE SUMMARY ............................................................................................................................ 1 1. INTRODUCTION .............................................................................................................................. 9 1.1 FOREWORD .............................................................................................................................................. 9 1.2 HISTORICAL CONTEXT ........................................................................................................................ 10 1.3 GOVERNANCE........................................................................................................................................ 10 1.3.1 Stormwater Management Authority ....................................................................... 10 1.3.2 Brown Hill Keswick Creek Stormwater Project ...................................................... 11 1.4 LIMITATIONS ........................................................................................................................................... 11 2. BACKGROUND .............................................................................................................................. 12 2.1 EARLIER STUDIES ................................................................................................................................. 12 2.2 2006 MASTER PLAN .............................................................................................................................. 12 2.3 2012 STORMWATER MANAGEMENT PLAN ..................................................................................... 14 2.4 STORMWATER PLANNING STRATEGY (SA GOVERNMENT) ...................................................... 14 3. STORMWATER MANAGEMENT OBJECTIVES ........................................................................... 16 3.1 SMA PLANNING GUIDELINES ............................................................................................................. 16 3.2 VISION ...................................................................................................................................................... 16 3.3 OBJECTIVES ........................................................................................................................................... 17 3.3.1 Protection from flooding ......................................................................................... 17 3.3.2 Quality of runoff and effect on receiving waters .................................................... 18 3.3.3 Beneficial reuse of stormwater runoff .................................................................... 19 3.3.4 Protection of watercourse and riparian ecosystems .............................................. 19 3.3.5 Effective planning outcomes .................................................................................. 19 3.3.6 Management of stormwater infrastructure ............................................................. 20 4. CATCHMENT DESCRIPTION ....................................................................................................... 21 4.1 CATCHMENT AREAS............................................................................................................................. 21 4.2 LAND USE AND STORMWATER RUNOFF CHARACTERISTICS .................................................. 22 4.3 INTENSIFICATION OF DEVELOPMENT ............................................................................................. 22 4.4 THE DRAINAGE SYSTEM ..................................................................................................................... 23 Stormwater Management Plan 2016 Contents | Page i 4.4.1 Brown Hill Creek .................................................................................................... 23 4.4.2 Parklands Creek .................................................................................................... 24 4.4.3 Glen Osmond Creek .............................................................................................. 24 4.4.4 Keswick Creek ....................................................................................................... 24 4.4.5 Concrete lining of creeks ....................................................................................... 25 5. EXISTING FLOOD PROBLEM ....................................................................................................... 26 5.1 FLOOD CHARACTERISTICS ................................................................................................................ 26 5.1.1 Brown Hill Creek .................................................................................................... 26 5.1.2 Parklands Creek .................................................................................................... 28 5.1.3 Glen Osmond Creek .............................................................................................. 29 5.1.4 Keswick Creek ....................................................................................................... 30 5.2 FLOOD RISK ............................................................................................................................................ 31 5.3 FLOOD DAMAGES ................................................................................................................................. 33 5.3.1 Direct tangible damages ........................................................................................ 33 5.3.2 Indirect tangible damages ...................................................................................... 34 5.3.3 Intangible costs ...................................................................................................... 34 5.3.4 Damages calculation method ................................................................................ 35 5.3.5 100 Year ARI flood damages ................................................................................. 37 5.3.6 Flood damages for other ARIs ............................................................................... 38 5.3.7 Average annual damages ...................................................................................... 39 6. OPPORTUNITIES FOR FLOOD MITIGATION AND STORMWATER MANAGEMENT .............. 40 6.1 STRUCTURAL FLOOD MITIGATION MEASURES ............................................................................ 40 6.1.1 Flood control dams ................................................................................................ 40 6.1.2 Detention basins and wetlands .............................................................................. 41 6.1.3 Overland flow interceptor culverts ......................................................................... 41 6.1.4 Flow diversions ...................................................................................................... 41 6.1.5 Flow bypasses ....................................................................................................... 42 6.1.6 Channel upgrades to increase capacity ................................................................ 42 6.1.7 Bridge / culvert upgrades ....................................................................................... 42 6.1.8 Other miscellaneous measures ............................................................................. 42 6.2 NON-STRUCTURAL FLOOD MITIGATION MEASURES .................................................................. 44 6.2.1 Planning policy ....................................................................................................... 44 6.2.2 Flood awareness and preparedness ..................................................................... 44 6.2.3 Flood warning and emergency response .............................................................. 45 6.2.4 Flood insurance ..................................................................................................... 46 6.2.5 Supporting policies and programs ......................................................................... 46 6.3