WDC Level 2 Strategic Flood Risk Assessment Report (SFRA)
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Level 2 SFRA Wycombe District Council Level 2 Strategic Flood Risk Assessment B127F005-03 | 03 September 2017 Level 2 Strategic Flood Risk Assessment Wycombe District Council Level 2 Strategic Flood Risk Assessment Level 2 SFRA Project No: B127F005 Document Title: Level 2 Strategic Flood Risk Assessment Document No.: B127F005-03 Revision: 03 Date: September 2017 Client Name: Wycombe District Council Client No: - Project Manager: Eve Lambourne Author: M Aspin File Name: F:\M Work\01_Projects\Wycombe SFRA L2\Deliverables\WORKING\Wycombe DC Level 2 SFRA Report v03e.docx Jacobs U.K. Limited Simpson House 6 Cherry Orchard Road Croydon CR9 6BE United Kingdom T +44 (0)20 8686 8212 F +44 (0)20 8681 2499 www.jacobs.com © Copyright 2017 Jacobs U.K. Limited. The concepts and information contained in this document are the property of Jacobs. Use or copying of this document in whole or in part without the written permission of Jacobs constitutes an infringement of copyright. Limitation: This report has been prepared on behalf of, and for the exclusive use of Jacobs’ Client, and is subject to, and issued in accordance with, the provisions of the contract between Jacobs and the Client. Jacobs accepts no liability or responsibility whatsoever for, or in respect of, any use of, or reliance upon, this report by any third party. Document history and status Revision Date Description By Review Approved 01 14/02/17 For client comment M Aspin M Symons E Lambourne 02 23/06/17 Addresses WDC and EA review comments M Aspin C Isherwood E Lambourne 03 18/08/17 Final M Aspin M Symons E Lambourne 04 06/08/17 Final for Local Plan submission M Aspin M Symons E Lambourne B127F005-03 ii Level 2 Strategic Flood Risk Assessment Contents 1. Introduction ................................................................................................................................................ 5 1.1 Background ................................................................................................................................................. 5 1.2 Requirement for a Level 2 SFRA ................................................................................................................ 5 1.3 Aims and Objectives .................................................................................................................................... 6 1.4 Wycombe Planning Policy ........................................................................................................................... 6 1.5 Study Area ................................................................................................................................................... 8 2. Methodology .............................................................................................................................................. 9 2.1 Approach ..................................................................................................................................................... 9 2.2 Delineation of Fluvial Flood Zones .............................................................................................................. 9 2.3 Flood Hazard ............................................................................................................................................. 11 2.4 Rate of Onset ............................................................................................................................................ 11 2.5 Consideration of Climate Change ............................................................................................................. 12 2.6 Surface Water Flooding ............................................................................................................................. 14 2.7 Groundwater Flooding ............................................................................................................................... 14 2.8 Sewer Flooding .......................................................................................................................................... 15 2.9 Flood Defence Failure ............................................................................................................................... 15 2.10 Reservoir Failure ....................................................................................................................................... 15 3. Individual Site Assessments .................................................................................................................. 16 3.1 Site 1: 1-9 Shaftesbury Street Detailed Assessment ................................................................................ 16 3.2 Site 5: Abbey Barn North Detailed Assessment ........................................................................................ 25 3.3 Site 7: Land to the rear of Hughenden Road, High Wycombe Detailed Assessment ............................... 33 3.4 Site 10: Former Bassetsbury Allotments, Bassetsbury Lane Detailed Assessment ................................. 41 3.5 Site 15: Hollands Farm (north), Bourne End Detailed Assessment .......................................................... 50 3.6 Site 21: Dashwood Avenue Detailed Assessment .................................................................................... 61 3.7 Site 45: Kingsmead Depot, High Wycombe Detailed Assessment ........................................................... 69 3.8 Site 70: Little Marlow Lakes Country Park Detailed Assessment ............................................................. 79 3.9 Site 90: Leigh Street, Desborough Area, High Wycombe Detailed Assessment ...................................... 89 3.10 Site 93: Slate Meadow, Bourne End Detailed Assessment ...................................................................... 97 3.11 Site 110: Princes Risborough Expansion Area Detailed Assessment .................................................... 107 3.12 Site 113: Princes Estate Expansion, Princes Risborough Detailed Assessment ................................... 115 3.13 Site 115: Land at Princes Risborough station, Princes Risborough Detailed Assessment .................... 121 3.14 Site 116: Land to the rear of Poppy Road, Princes Risborough Detailed Assessment .......................... 129 3.15 Site 137: Land North of Lower Icknield Way, Longwick Site Detailed Assessment ................................ 136 3.16 Site 141: Westhorpe House Detailed Assessment ................................................................................. 143 4. Sustainable Flood Risk Management .................................................................................................. 152 4.1 Site Allocations ........................................................................................................................................ 152 4.2 Planning Advice and Windfall Sites ......................................................................................................... 153 4.3 Relocation of Unsuitable Existing Development ..................................................................................... 155 4.4 Safeguarding ........................................................................................................................................... 155 B127F005-03 iii Level 2 Strategic Flood Risk Assessment 4.5 Wycombe Critical Drainage Areas .......................................................................................................... 156 4.6 LLFA Requirements ................................................................................................................................ 157 4.7 Opportunities to Reduce Flooding ........................................................................................................... 157 4.8 Restriction of Permitted Development Rights ......................................................................................... 158 4.9 Princes Risborough Drainage Strategy ................................................................................................... 158 4.10 General Recommendations – Minimising Flood Risk and Impacts ......................................................... 158 5. Recommendations ................................................................................................................................ 163 5.1 Hydraulic Modelling ................................................................................................................................. 163 5.2 Allocation Site Summary ......................................................................................................................... 163 Appendix A. Allocation Site Schedule Appendix B. Lower Risk Sites Assessment Appendix C. Hydraulic Modelling Report Appendix D. Climate Change Extents Plans B127F005-03 iv Level 2 Strategic Flood Risk Assessment 1. Introduction Wycombe District Council (WDC) commissioned Jacobs UK in November 2016 to undertake a Level 2 Strategic Flood Risk Assessment (SFRA) leading on from the Level 1 SFRA prepared by the Council in November 20141. This Level 2 SFRA has been prepared in accordance with the National Planning Policy Framework (NPPF). 1.1 Background WDC is in the process of producing an emerging Local Plan which outlines the Council’s long-term development aspirations for the period 2013-2033. Once adopted, this will replace the existing adopted plan for the District. As part of the supporting evidence to the Local Plan, information is required on the probability