Uciam Noriaci Enatio Et L
Total Page:16
File Type:pdf, Size:1020Kb
Luton and South Bedfordshire Joint Committee Local Development Framework Strategic Flood Risk Assessment: Level 1 September 2008 LBC & SBDC Level 1 Strategic Flood Risk Assessment Revision Schedule Luton Borough Council and South Bedfordshire District Council Level 1 Strategic Flood Risk Assessment Project Date Details Prepared by Reviewed by Approved by Number D112147 November LBC & SBDC Stephen Riley Jon Robinson Jon Robinson 2007 Level 1 SFRA Senior Consultant Associate Director Associate Director Rev 3.0.doc D121443 August 2008 LBC SBDC Stephen Riley Jon Robinson Jon Robinson Level 1 SFRA Senior Consultant Associate Director Associate Director Rev 3.2.doc D121443 September LBC SBDC Stephen Riley Jon Robinson Jon Robinson 2008 Level 1 SFRA Senior Consultant Associate Director Associate Director Rev 3.2_EA- edits.doc Scott Wilson Scott House Alençon Link Basingstoke Hampshire This document has been prepared for the titled project or named RG21 7PP part thereof and should not be relied upon or used for any other project without an independent check being carried out as to its suitability and prior written authority of Scott Wilson being obtained. Tel. 01256 310200 Scott Wilson accepts no responsibility or liability for the Fax. 01256 310201 consequence of this document being used for a purpose other than the purposes for which it was commissioned. Any person using or www.scottwilson.com relying on the document for such other purpose agrees, and will by such use or reliance be taken to confirm his agreement to indemnify Scott Wilson for all loss or damage resulting there from. Scott Wilson accepts no responsibility or liability for this document to any party other than the person by whom it was commissioned. LBC & SBDC Level 1 Strategic Flood Risk Assessment Table of Contents 1 Introduction.................................................................................... 1 1.1 The Luton BC and South Bedfordshire DC SFRA......................................................1 1.2 SFRA Structure ..........................................................................................................2 1.3 Aim of the SFRA.........................................................................................................3 1.4 SFRA Objectives ........................................................................................................3 1.5 Level 1 SFRA Report Synopsis..................................................................................4 2 The Luton BC and South Bedfordshire DC SFRA Study Area ...... 5 2.1 Local Watercourses....................................................................................................5 2.2 Hydrogeology/Groundwater .......................................................................................7 2.3 Sewers .......................................................................................................................7 2.4 Overland flow .............................................................................................................7 2.5 Artificial Sources.........................................................................................................8 3 Policy Context ............................................................................... 9 3.1 Role and Responsibilities ...........................................................................................9 3.2 European Policies (EU) ............................................................................................11 3.3 National Policies.......................................................................................................12 3.4 Regional Policies......................................................................................................13 3.5 Local Policies ...........................................................................................................15 3.6 Environment Agency Policies...................................................................................17 3.7 Other Local Policies .................................................................................................19 4 Data Collection & Review............................................................ 21 4.1 Project Approach......................................................................................................21 4.2 Data Review / Overview ...........................................................................................22 4.3 Flood Defences ........................................................................................................27 5 SFRA Mapping ............................................................................ 34 5.1 Requirements of PPS25...........................................................................................34 5.2 GIS Layers and Mapping..........................................................................................34 5.3 Fluvial Flooding ........................................................................................................35 5.4 Sewer Flooding ........................................................................................................39 5.5 Groundwater Flooding..............................................................................................40 LBC & SBDC Level 1 Strategic Flood Risk Assessment 5.6 Overland Flow / Pluvial Flooding..............................................................................41 5.7 Artificial Sources (Infrastructure Failure) ..................................................................41 5.8 Residual Risk ...........................................................................................................41 6 Guidance on Applying the PPS25 Sequential Test ..................... 43 6.1 What is the Sequential Test? ...................................................................................43 6.2 How should the SFRA be used to apply the Sequential Test?.................................45 6.3 Additional Guidance .................................................................................................46 7 Guidance on Applying the PPS25 Exception Test ...................... 48 7.1 What is the Exception Test?.....................................................................................48 7.2 Why is there an Exception Test?..............................................................................48 7.3 What is required to pass the Exception Test?..........................................................48 8 Future Flood Risk Management Practices .................................. 51 8.1 Strategic Flood Defences .........................................................................................51 8.2 Flood Warning ..........................................................................................................52 8.3 Flood Alleviation Scheme Maintenance ...................................................................52 8.4 Flood Mitigation on site ............................................................................................53 9 Drainage of Development Sites................................................... 55 9.1 Background ..............................................................................................................55 9.2 What are SuDS? ......................................................................................................56 9.3 SuDS Policies...........................................................................................................56 9.4 Achieving SuDS in Developments............................................................................59 9.5 SuDS Techniques ....................................................................................................59 9.6 SuDS Design............................................................................................................62 9.7 Where can SuDS be utilised? ..................................................................................62 9.8 SuDS Constraints.....................................................................................................63 9.9 Further Information...................................................................................................64 10 Policy Recommendations............................................................ 66 10.1 Flood Risk ................................................................................................................66 10.2 Flood Mitigation Measures .......................................................................................67 10.3 Drainage Systems ....................................................................................................69 10.4 Water Resources & Environment .............................................................................71 11 Site Specific Flood Risk Assessment Guidance.......................... 72 LBC & SBDC Level 1 Strategic Flood Risk Assessment 11.1 When are Flood Risk Assessments Required?........................................................73 11.2 Flood Risk Assessment Requirements ....................................................................74 11.3 Flood Risk Assessment Guidance Table .................................................................76 12 Emergency Planning ................................................................... 88 12.1 Developing an Emergency Flood Plan .....................................................................88 12.2 Use of the Emergency