East Northamptonshire Council Level 1 Strategic Flood Risk Assessment Review and Update Final August 2011 Prepared for East Northamptonshire Council Level 1 Strategic Flood Risk Assessment Review Revision Schedule Level 1 Strategic Flood Risk Assessment Review and Update August 2011 Rev Date Details Prepared by Reviewed by Approved by 01 March 2011 Interim Draft Gemma Costin Michael Timmins Michael Timmins D01 Assistant Consultant Principal Consultant Principal Consultant Fay Tivey Consultant 02 June 2011 Final Draft D01 Fay Tivey Michael Timmins Michael Timmins Consultant Principal Consultant Principal Consultant 03 August 2011 Final F01 Fay Tivey Michael Timmins Michael Timmins Senior Consultant Associate Associate URS/Scott Wilson Royal Court Basil Close Chesterfield This document has been prepared in accordance with the scope of URS Scott Wilson's Derbyshire appointment with its client and is subject to the terms of that appointment. 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The contents of this document do not provide legal or tax advice or opinion. © URS Scott Wilson Ltd 2011 www. urs -scottwilson.com East Northamptonshire Council Level 1 Strategic Flood Risk Assessment Review Table of Contents Table of Contents........................................................................................ i Executive Summary....................................................................................i Strategic Flood Risk Assessment .................................................................................................. i Study Area .................................................................................................................................... i Information Sources ..................................................................................................................... ii Technical Guidance...................................................................................................................... ii Summary and Recommendations ................................................................................................iii Abbreviations ............................................................................................ iv Glossary ..................................................................................................... v Strategic Flood Risk Assessment Pro Forma....................................... viii 1 Introduction ..................................................................................... 1 1.1 Background .................................................................................................................... 1 1.2 SFRA Overview .............................................................................................................. 1 1.3 SFRA Aims and Objectives.............................................................................................2 1.4 Roles and Responsibilities.............................................................................................. 2 2 East Northamptonshire Study Area ............................................... 4 2.1 Study Area...................................................................................................................... 4 2.2 Key Flood Sources ......................................................................................................... 5 3 Sequential Approach to Site Allocation......................................... 7 3.1 Sequential Test............................................................................................................... 7 3.2 Development Vulnerability .............................................................................................. 7 3.3 Sources of Flooding........................................................................................................ 9 3.4 Application of the Sequential Test...................................................................................9 3.5 Exception Test.............................................................................................................. 11 3.6 Windfall Sites................................................................................................................ 11 3.7 Additional Guidance...................................................................................................... 12 4 Level 1 SFRA Review Methodology ............................................. 13 4.1 Overview ...................................................................................................................... 13 4.2 Tasks............................................................................................................................ 13 4.3 Stakeholders................................................................................................................. 13 4.4 Information/Data Collected ........................................................................................... 13 4.5 Flooding from Rivers..................................................................................................... 16 4.6 Flooding from the Land................................................................................................. 16 Final August 2011 East Northamptonshire Council Level 1 Strategic Flood Risk Assessment Review 4.7 Flooding from Groundwater .......................................................................................... 17 4.8 Flooding from Sewers................................................................................................... 17 4.9 Flooding from Reservoirs, Canals and Other Artificial Sources..................................... 17 4.10 Consideration of Climate Change ................................................................................. 17 5 Existing East Northamptonshire Council Level 1 SFRA............. 19 5.1 Introduction................................................................................................................... 19 5.2 Summary of 2006 SFRA Findings................................................................................. 19 5.3 Limitations of the Existing (2006) SFRA........................................................................ 20 6 Strategic Flood Risk Assessment Update................................... 21 6.1 East Northamptonshire Flooding History....................................................................... 21 6.2 Flooding from Rivers..................................................................................................... 22 6.3 Flooding from Land....................................................................................................... 24 6.4 Flooding from Groundwater .......................................................................................... 24 6.5 Flooding from Sewers................................................................................................... 25 6.6 Flooding from Reservoirs, Canals and Other Artificial Sources..................................... 25 6.7 Flood Risk Management Infrastructure ......................................................................... 26 6.8 Climate Change............................................................................................................ 27 6.9 Residual Risk................................................................................................................ 28 6.10 Emergency Planning..................................................................................................... 28 6.11 Flood Warning Areas.................................................................................................... 29 7 Policy Review & Recommendations ............................................ 32 7.1 Overview ...................................................................................................................... 32 7.2 Catchment Flood Management Plans........................................................................... 32 7.3 Water Cycle Strategies ................................................................................................. 34 7.4 Flood Risk Policy .......................................................................................................... 34 7.5 Sustainable Drainage Systems..................................................................................... 35 8 Flood Risk Assessment Guidance............................................... 37 8.1 Overview ...................................................................................................................... 37 8.2 When is a FRA Required? ............................................................................................ 37 8.3 FRA Scope and Requirements ..................................................................................... 37 9 Level 2 SFRA Recommendations................................................. 41 9.1 Sites potentially requiring