Braintree District Council Strategic Flood Risk Assessment Appendix A Braintree Supplementary Report Report July 2008 Prepared for: Photographs of Townsford Mill, Halstead and the River Stour at Pentlow Mill courtesy of Christopher Strickland Braintree District Council D111532 Strategic Flood Risk Assessment Revision Schedule Mid Essex Strategic Flood Risk Assessment July 2008 Rev Date Details Prepared by Reviewed by Approved by 01 August 07 Draft SFRA for Nick Bosanko Liz Williams Jon Robinson comments Flood Risk Specialist Senior Consultant Associate 02 January 08 Final Draft Eleanor Cole Liz Williams SFRA Graduate Hydrologist Senior Consultant 03 April 08 Final SFRA Eleanor Cole Liz Williams Assistant Hydrologist Senior Consultant 04 May 08 Final SFRA Eleanor Cole Liz Williams Assistant Hydrologist Senior Consultant 05 July 08 Final SFRA Eleanor Cole Jon Robinson Assistant Hydrologist Associate Director Scott Wilson 6-8 Greencoat Place, This document has been prepared in accordance with the scope of Scott Wilson's appointment with its client and is subject to the terms of that appointment. It is addressed London, to and for the sole use and reliance of Scott Wilson's client. Scott Wilson accepts no liability for any use of this document other than by its client and only for the purposes, SW1P 1PL stated in the document, for which it was prepared and provided. No person other than the client may copy (in whole or in part) use or rely on the contents of this document, without the prior written permission of the Company Secretary of Scott Wilson Ltd. Any advice, opinions, or recommendations within this document should be read and relied upon only in the context of the document as a whole. The contents of this document are not to be Tel: 020 7798 5200 construed as providing legal, business or tax advice or opinion. Fax: 020 7798 5001 © Scott Wilson Group PLC 2006 www.scottwilson.com Braintree District Council D111532 Strategic Flood Risk Assessment Table of Contents 1 Non-Technical Summary.................................................................... 1 1.1 SFRA Background............................................................................................................ 1 1.2 SFRA Planning Objectives ............................................................................................... 1 1.3 SFRA Report Layout ........................................................................................................ 2 1.4 Braintree District Council Considerations......................................................................... 2 1.5 Way Forward .................................................................................................................... 4 1.6 A Living Document ........................................................................................................... 5 2 Introduction and Background.............................................................. 6 2.2 Scope and Objectives ...................................................................................................... 6 2.3 Report Structure ............................................................................................................... 7 2.4 Braintree District Council Area ......................................................................................... 7 3 Sources of Flooding in Braintree ...................................................... 10 3.1 Introduction..................................................................................................................... 10 3.2 Fluvial ............................................................................................................................. 12 3.3 Overland Flow ................................................................................................................ 15 3.4 Arterial Drainage Network .............................................................................................. 17 3.5 Groundwater................................................................................................................... 19 4 Level 1 Assessment ......................................................................... 20 4.1 Level 1 SFRA – Study Area, Flood Source Review and Data Review........................... 20 4.2 Level 1 Mapping Methodology ....................................................................................... 21 5 Level 2 Assessment ......................................................................... 23 5.1 Overview ........................................................................................................................23 5.2 Fluvial ............................................................................................................................. 23 5.3 Overland Flow ................................................................................................................ 24 5.4 Arterial Drainage Network .............................................................................................. 25 5.5 Strategic Spatial Flood Source Summary....................................................................... 27 6 Bramston Sports Centre................................................................... 31 6.1 Introduction..................................................................................................................... 31 6.2 Site and Surrounding Area ............................................................................................. 31 6.3 Regulatory Position ........................................................................................................ 33 6.4 Flood Status and Sources .............................................................................................. 36 6.5 Assessment of Flood Risk.............................................................................................. 38 6.6 Potential Development Considerations .......................................................................... 39 Braintree District Council D111532 Strategic Flood Risk Assessment 6.7 Flood Mitigation and Management ................................................................................. 41 6.8 Bramston Sports Centre Conclusions ............................................................................ 44 7 Water Discharges............................................................................. 46 7.2 Effect of Development in Braintree................................................................................. 46 7.3 Mitigation ........................................................................................................................ 47 8 SuDS Specific to Braintree............................................................... 48 8.1 Introduction..................................................................................................................... 48 8.2 Geology .......................................................................................................................... 48 8.3 SuDS Recommendations ............................................................................................... 52 9 Policy Specific Requirements to Braintree District ........................... 54 9.2 Flood Risk ......................................................................................................................54 9.3 Sustainable Drainage Systems (SuDS) ......................................................................... 55 9.4 Flood Mitigation .............................................................................................................. 56 9.5 Water Environment......................................................................................................... 57 10 Recommendations ........................................................................... 59 11 References ....................................................................................... 60 12 Blackwater Modelling Report by Atkins ............................................ 61 Braintree Figures Appendix Braintree District Council D111532 Strategic Flood Risk Assessment List Figures Figure Number Description Area A1 Braintree District Location Map A2 District Wide Fluvial Flood Risk Map A3-1 Flood Zones 2007 Land East of Stebbing A3-2 Flood Zones 2107 Land East of Stebbing A4-1 Flood Zones 2007 Land West of Rayne A4-2 Flood Zones 2107 Land West of Rayne A5-1 Flood Zones 2007 Land East of Rayne A5-2 Flood Zones 2107 Land East of Rayne A6-1 Flood Zones 2007 Land South West of Great Notley A6-2 Flood Zones 2107 Land South West of Great Notley A7-1 Flood Zones 2007 Land East of Great Notley A7-2 Flood Zones 2107 Land East of Great Notley A8-1 Flood Zones 2007 Land South West of Braintree (Off London Road) A8-2 Flood Zones 2107 Land South West of Braintree (Off London Road) A9-1 Flood Zones 2007 Land North of Springwood Industrial Area, Braintree A9-2 Flood Zones 2107 Land North of Springwood Industrial Area, Braintree A10-1 Flood Zones 2007 Land at Dorewards Hall, Bocking A10-2 Flood Zones 2107 Land at Dorewards Hall, Bocking A11-1 Flood Zones 2007 Land North East of Braintree A11-2 Flood Zones 2107 Land North East of Braintree A12-1 Flood Zones 2007 Land Adjacent to Galleys Corner, Braintree A12-2 Flood Zones 2107 Land Adjacent to Galleys Corner, Braintree A13-1 Flood Zones 2007 Land South West of Silver End A13-2 Flood Zones 2107 Land South West of Silver End A14-1 Flood Zones 2007 Land East of Panfield Lane A14-2 Flood Zones 2107 Land East