Milton Keynes Level 1 Strategic Flood Risk Assessment (April 2015)
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Milton Keynes Level 1 Strategic Flood Risk Assessment Final Report April 2015 47070452 UNITED KINGDOM & IRELAND Prepared for: Milton Keynes Council — Level 1 SFRA Update REVISION SCHEDULE Rev Date Details Prepared by Reviewed by Approved by 1 September Draft for Comment Sarah Littlewood Elizabeth Gent Elizabeth Gent 2014 Consultant Principal Consultant Principal Consultant Richard Karooni Consultant Ewan McCracken Consultant 2 April 2015 Final Report Sarah Littlewood Helen Judd Jon Robinson (incorporating Consultant Senior Consultant Operations Director - comments from Water MKC, the Joanna Bolding Environment Consultant Agency and Bedford Group of Gemma Hoad Drainage Boards) Senior Consultant URS Infrastructure and Environment UK Ltd 6-8 Greencoat Place London SW1P 1PL United Kingdom Telephone: +44(0)20 7798 5000 Fax: +44(0)20 7798 5001 LEVEL 1 STRATEGIC FLOOD RISK ASSESSMENT 47070452 April 2015 i Milton Keynes Council — Level 1 SFRA Update Limitations URS Infrastructure & Environment UK Limited (“URS”) has prepared this Report for the sole use of Milton Keynes Council (“Client”) in accordance with the Agreement under which our services were performed (URS Quotation of Services ‘Milton Keynes SFRA Level 1 Update - Quotation of Services.pdf). No other warranty, expressed or implied, is made as to the professional advice included in this Report or any other services provided by URS. The conclusions and recommendations contained in this Report are based upon information provided by others and upon the assumption that all relevant information has been provided by those parties from whom it has been requested and that such information is accurate. Information obtained by URS has not been independently verified by URS, unless otherwise stated in the Report. The methodology adopted and the sources of information used by URS in providing its services are outlined in this Report. The work described in this Report was undertaken between May 2014 and April 2015 and is based on the conditions encountered and the information available during the said period of time. The scope of this Report and the services are accordingly factually limited by these circumstances. Where assessments of works or costs identified in this Report are made, such assessments are based upon the information available at the time and where appropriate are subject to further investigations or information which may become available. URS disclaim any undertaking or obligation to advise any person of any change in any matter affecting the Report, which may come or be brought to URS’ attention after the date of the Report. Certain statements made in the Report that are not historical facts may constitute estimates, projections or other forward- looking statements and even though they are based on reasonable assumptions as of the date of the Report, such forward-looking statements by their nature involve risks and uncertainties that could cause actual results to differ materially from the results predicted. URS specifically does not guarantee or warrant any estimate or projections contained in this Report. Copyright © This Report is the copyright of URS Infrastructure & Environment UK Limited. Any unauthorised reproduction or usage by any person other than the addressee is strictly prohibited. LEVEL 1 STRATEGIC FLOOD RISK ASSESSMENT 47070452 April 2015 ii Milton Keynes Council — Level 1 SFRA Update TABLE OF CONTENTS ABBREVIATIONS ................................ ................................ ................ V GLOSSARY OF TERMS .................................................................... VII 1 INTRODUCTION ............................................................... 1 1.1 Terms of Reference ......................................................... 1 1.2 Project Aims ..................................................................... 1 1.3 Project Deliverables......................................................... 3 1.4 Partner Organisations ..................................................... 3 1.5 Milton Keynes Study Area .............................................. 4 2 LEGISLATIVE AND PLANNING POLICY CONTEXT ...... 7 2.1 Introduction ...................................................................... 7 2.2 Flood and Water Management Act ................................. 7 2.3 Flood Risk Regulations ................................................... 8 2.4 Anglian River Basin District draft Flood Risk Management Plan ............................................................ 8 2.5 National Planning Policy Framework............................. 9 2.6 Local Planning Policy ...................................................... 9 2.7 IDB Policy ....................................................................... 10 3 STUDY METHODOLOGY ............................................... 13 3.1 Level 1 SFRA Methodology .......................................... 13 3.2 Need for a Level 2 SFRA ............................................... 14 4 FLOOD RISK IN MILTON KEYNES ............................... 15 4.1 Introduction .................................................................... 15 4.2 Flooding from Rivers ..................................................... 15 4.3 Flooding from Surface Water ....................................... 23 4.4 Flooding from Groundwater ......................................... 25 4.5 Flooding from Sewers ................................................... 29 4.6 Flooding from Reservoirs, Canals and Other Artificial Sources ........................................................................... 29 4.7 Flood Risk Management Measures .............................. 31 5 FLOOD RISK MANAGEMENT POLICY CONSIDERATIONS ........................................................ 41 5.1 Policy Considerations ................................................... 41 5.2 Council Specific Policy Issues ..................................... 43 5.3 Sensitive Development Locations ............................... 43 6 GUIDANCE FOR THE APPLICATION OF THE SEQUENTIAL TEST ........................................................ 45 6.1 Sequential Approach ..................................................... 45 6.2 Applying the Sequential Test – Plan-Making .............. 45 LEVEL 1 STRATEGIC FLOOD RISK ASSESSMENT 47070452 April 2015 iii Milton Keynes Council — Level 1 SFRA Update 6.3 Applying the Sequential Test – Planning Applications 48 6.4 Exception Test ............................................................... 50 7 GUIDANCE FOR SITE SPECIFIC FLOOD RISK ASSESSMENTS .............................................................. 53 7.1 When is a Flood Risk Assessment required? ............. 53 7.2 What should a Flood Risk Assessment address? ..... 53 7.3 Guidance on Flood Risk Management Measures ....... 57 8 GUIDANCE FOR THE APPLICATION OF SUDS .......... 64 8.1 Introduction .................................................................... 64 8.2 Use of Infiltration SuDS in Milton Keynes ................... 69 8.3 National SuDS Standards ............................................. 71 9 SUMMARY AND RECOMMENDATIONS ....................... 72 9.1 Site Allocation Process ................................................. 72 9.2 Council Policy ................................................................ 72 9.3 Future Updates to the SFRA ......................................... 72 9.4 Level 2 SFRA .................................................................. 73 APPENDIX A DATA REGISTER ....................................................... 74 APPENDIX B STUDY AREA MAPPING ........................................... 78 APPENDIX C FLUVIAL FLOOD ZONE MAPPING........................... 80 APPENDIX D SURFACE WATER FLOOD RISK MAPPING ........... 82 LEVEL 1 STRATEGIC FLOOD RISK ASSESSMENT 47070452 April 2015 iv Milton Keynes Council — Level 1 SFRA Update ABBREVIATIONS ACRONYM DEFINITION ABD Areas Benefiting from Defences AEP Annual Exceedance Probability AOD Above Ordnance Datum AIMS Asset Information Management System AStSWF Areas Susceptible to Surface Water Flooding AWS Anglian Water Services BGDB Bedford Group of Drainage Boards BGS British Geological Survey CFMP Catchment Flood Management Plan Construction Industry Research and Information CIRIA Association DA Designated Area (Milton Keynes) Defra Department for Environment, Flood and Rural Affairs DPD Development Plan Document EU European Union FCERM Flood and Coastal Erosion Risk Management FEH Flood Estimation Handbook FRA Flood Risk Assessment FRMP Flood Risk Management Plan FWMA Flood and Water Management Act 2010 GIS Geographic Information Systems HCA Homes and Communities Agency IDB Internal Drainage Board LFRMS Local Flood Risk Management Strategy LiDAR Light Detection and Ranging LLFA Lead Local Flood Authority LPA Local Planning Authority LRF Local Resilience Forum LEVEL 1 STRATEGIC FLOOD RISK ASSESSMENT 47070452 April 2015 v Milton Keynes Council — Level 1 SFRA Update MKC Milton Keynes Council MKPT Milton Keynes Parks Trust NPPF National Planning Policy Framework NPPG National Planning Policy Guidance PFRA Preliminary Flood Risk Assessment PPS25 Planning Policy Statement 25 RSS Regional Spatial Strategies SFRA Strategic Flood Risk Assessment SLA Strategic Land Allocation SoP Standard of Protection SPG Supplementary Planning Guidance SPZ Source Protection Zone SuDS Sustainable Drainage Systems uFMfSW Updated Flood Map for Surface Water UKCP09 UK Climate Projections 2009 LEVEL 1 STRATEGIC FLOOD RISK ASSESSMENT 47070452 April 2015 vi Milton Keynes Council