South Essex Surface Water Management Plan Phases II, III and IV FINAL April 2012 Prepared for South Essex South Essex Surface Water Management Plan – Phase II, III and IV Revision Schedule South Essex Surface Water Management Plan – Phases II, III and IV April 2012 Rev Date Details Prepared by Reviewed by Approved by 01 Oct 2011 Draft Report v1 Gemma Hoad Carl Pelling Michael Timmins Assistant Water Scientist Principal Consultant Associate Consultant Danielle Skilton Graduate Hydrologist 02 Apr 2012 Final Gemma Hoad Carl Pelling Carl Pelling Assistant Water Scientist Principal Consultant Principal Consultant URS Scott House Alençon Link Basingstoke Hampshire RG21 7PP United Kingdom Tel: +44 (0)1256 310 200 Fax: +44 (0)1256 310 201 South Essex Surface Water Management Plan – Phase II, III and IV Executive Summary ..................................................................................... i Glossary of Terms and Acronyms.......................................................... viii 1. Introduction and Aims ..................................................................... 1 1.1 Introduction....................................................................................................................... 1 1.2 Study Area........................................................................................................................ 1 1.3 Summary of Phase 1........................................................................................................ 2 1.4 Aims and Objectives of Phases 2, 3 and 4....................................................................... 2 1.5 SWMP Report Presentation ............................................................................................. 3 Phase II: Risk Assessment......................................................................... 4 Part A: Study Wide ...................................................................................... 5 2. Introduction ...................................................................................... 6 2.1 Intermediate Assessment................................................................................................. 6 2.2 Risk Overview .................................................................................................................. 7 3. Sources of Flooding....................................................................... 11 3.1 Surface Water Flooding.................................................................................................. 11 3.2 Ordinary Watercourses .................................................................................................. 12 3.3 Groundwater Flooding.................................................................................................... 13 3.4 Sewer Flooding .............................................................................................................. 16 4. Critical Drainage Areas.................................................................. 19 4.1 Potential Surface Water Flooding Hotspots ................................................................... 19 4.2 Property Count ...............................................................................................................20 4.3 Shortlisting...................................................................................................................... 20 4.4 Mapping Outputs ............................................................................................................ 22 5. Communicating Risk...................................................................... 23 5.1 Professional Stakeholders.............................................................................................. 23 5.2 Local Resilience Forums ................................................................................................ 23 5.3 Communication and Engagement Plan.......................................................................... 23 Part B: Flood Risk ..................................................................................... 24 6. Basildon Borough Council ............................................................ 25 6.1 Surface Water Flooding.................................................................................................. 25 6.2 Ordinary Watercourses .................................................................................................. 25 6.3 Groundwater Flooding.................................................................................................... 26 6.4 Sewer Flooding .............................................................................................................. 26 6.5 Critical Drainage Area .................................................................................................... 27 6.6 Summary of Flood Risk .................................................................................................. 50 South Essex Surface Water Management Plan – Phase II, III and IV 7. Castle Point Borough Council....................................................... 52 7.1 Surface Water Flooding.................................................................................................. 52 7.2 Ordinary Watercourses .................................................................................................. 52 7.3 Groundwater Flooding.................................................................................................... 53 7.4 Sewer Flooding .............................................................................................................. 54 7.5 Critical Drainage Areas .................................................................................................. 54 7.6 Summary of Flood Risk .................................................................................................. 62 8. Rochford District Council.............................................................. 65 8.1 Surface Water Flooding.................................................................................................. 65 8.2 Ordinary Watercourses .................................................................................................. 65 8.3 Groundwater Flooding.................................................................................................... 66 8.4 Sewer Flooding .............................................................................................................. 66 8.5 Critical Drainage Areas .................................................................................................. 67 8.6 Summary of Flood Risk .................................................................................................. 77 Phase III: Options Assessment................................................................ 79 Part A: Study Wide .................................................................................... 80 9. Introduction .................................................................................... 81 9.1 Objectives....................................................................................................................... 81 9.2 Linkages to Local Investment Plans............................................................................... 81 10. Options Identification & Assessment........................................... 82 10.1 Methodology................................................................................................................... 82 10.2 Borough Wide Options ................................................................................................... 89 Part B: Preferred Options ....................................................................... 103 11. Basildon Borough Council .......................................................... 104 11.1 CDA Preferred Options ................................................................................................ 104 11.2 Preferred Options Summary......................................................................................... 123 12. Castle Point Borough Council..................................................... 126 12.1 CDA Preferred Options ................................................................................................ 126 12.2 Preferred Options Summary......................................................................................... 135 13. Rochford District Council............................................................ 137 13.1 CDA Preferred Options ................................................................................................ 137 13.2 Preferred Options Summary......................................................................................... 149 Phase IV: Implementation and Review.................................................. 152 Part A: Study Wide .................................................................................. 153 South Essex Surface Water Management Plan – Phase II, III and IV 14. Implementation & Review............................................................ 154 14.1 Action Plan ................................................................................................................... 154 14.2 Essex County Council Actions ..................................................................................... 155 Part B: Council Action Plans.................................................................. 158 15. Basildon Borough Council Action Plan ....................................