Corby Strategic Flood Risk Assessment - Stage 2 Final Report
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Corby Strategic Flood Risk Assessment - Stage 2 Final Report Corby Borough Council August 2006 - This page left blank intentionally - Faber Maunsell Corby Strategic Flood Risk Assessment - Stage 2 i Table of Contents Lists of Tables & Figures.................................................................................................... iii Executive Summary ............................................................................................................. v 1 Introduction .............................................................................................................. 1 2 Flood Risk................................................................................................................. 5 Planning Policy Guidance Note 25 ............................................................................ 5 Circular 30/92 Maps ................................................................................................... 6 Indicative Floodplain Maps.........................................................................................6 3 Causes of Flooding.................................................................................................. 9 Overflowing of Watercourses.....................................................................................9 Localised Flooding ................................................................................................... 10 Mechanical, Structural or Operational Failure.......................................................... 11 4 Flooding in Corby .................................................................................................. 13 Classes of Flooding.................................................................................................. 13 Records of Flooding ................................................................................................. 14 Corby Borough Council................................................................................ 14 Environment Agency.................................................................................... 15 Storm Drainage Studies Report by John Taylor & Sons ............................. 15 Anglian Water Services ............................................................................... 18 Flood Alleviation Measures...................................................................................... 19 Gretton Brook............................................................................................... 19 Willow Brook - North Arm .......................................................................... 20 Willow Brook - Central Arm........................................................................ 22 Willow Brook - South Arm.......................................................................... 25 Harpers Brook.............................................................................................. 28 Operational and Emergency Planning ..................................................................... 30 5 Strategic Assessment of Flood Risk.................................................................... 33 General Methodology............................................................................................... 33 Topographic Divisions.............................................................................................. 35 Anthropogenic Influences......................................................................................... 36 The River Nene Model ............................................................................................. 39 Flood Risk Mapping ................................................................................................. 41 Rapid Inundation Hazard Zones .............................................................................. 43 6 Planning Policy and Flood Risk............................................................................ 45 Milton Keynes South Midlands Strategy .................................................................. 45 Northamptonshire County Structure Plan ................................................................ 48 Corby Local Plan...................................................................................................... 49 Catalyst Corby (North Northamptonshire Development Company)........................ 50 Guidance for Developers ......................................................................................... 52 Continued over …. Faber Maunsell Corby Strategic Flood Risk Assessment - Stage 2 ii Continued …. 7 Assessment of Flood Risk in Development Areas ............................................. 53 8 Potential Development Areas in Corby................................................................ 57 Western Extension ................................................................................................... 59 Southern Extension.................................................................................................. 63 Northern Extension .................................................................................................. 65 Oakley / Stanion Extension ...................................................................................... 67 Priors Hall & Weldon Extensions ........................................................................... 71 Great Oakley Extension ........................................................................................... 75 Weldon North Industrial Estate ................................................................................ 77 St James Industrial Estate ....................................................................................... 79 Corby East................................................................................................................ 81 Weldon South Industrial Estate and Max Park ...................................................... 83 9 Conclusions............................................................................................................ 85 10 Recommendations ................................................................................................. 87 References .......................................................................................................................... 89 APPENDICES Appendix 1 Figures Appendix 2 Photographs Appendix 3 Environment Agency – Regional Flood Defence & Land Drainage Operational Plan for the Corby Borough Council Area Appendix 4 ISIS Model – Input Data and Results Appendix 5 Flood Risk Guidance Notes to Developers Appendix 6 Flood Risk Standing Advice Matrix (and Explanatory Notes) Faber Maunsell Corby Strategic Flood Risk Assessment - Stage 2 iii Lists of Tables & Figures LIST OF TABLES Table 1 PPG25 Flood Risk Zones Table 2 Properties Flooded by the Storm of 30 th July 1982 Table 3 Soot Banks Flood Storage Reservoir - Design Criteria Table 4 Oakley Vale Ponds - Storage Volumes Table 5 Responsibilities & Routine Actions for Flood Defence Table 6 Operational Emergency Response Arrangements Table 7 Future Housing Allocation in Northamptonshire Table 8 Areas Proposed for Industry in the Corby Local Plan Table 9 Indicative Standards for Fluvial Flood Defence Table 10 High Risk Category – Flood Risk Sub-Divisions LIST OF FIGURES Figure 1 Location Plan Figure 2 Potential Development Areas Figure 3 Critical Ordinary Watercourses Figure 4 Extent of Flooding, 30 th July 1982 Figure 5 Principal Hydraulic Installations in Corby (Two sheets) Figure 6 Strategic Flood Risk Maps (Six sheets) Figure 7 ISIS Model Sub-Catchments (Existing Urbanisation) Figure 8 ISIS Model Sub-Catchments (Proposed Urbanisation) Figure 9 ISIS Model Channel Cross-Section Locations Potential Development Area Plans Figure 10.1 Western Extension Figure 10.2 Southern Extension Figure 10.3 Northern Extension Figure 10.4 Oakley / Stanion Extension Figure 10.5 Priors Hall and Weldon Extensions Figure 10.6 Great Oakley Extension Figure 10.7 Weldon North Industrial Estate Figure 10.8 St James Industrial Estate Figure 10.9 Corby East Figure 10.10 Weldon South Industrial Estate & Max Park Faber Maunsell Corby Strategic Flood Risk Assessment - Stage 2 iv - This page left blank intentionally – Faber Maunsell Corby Strategic Flood Risk Assessment - Stage 2 v Executive Summary The Department of Transport, Local Government and the Regions' Planning Policy Guidance Note 25 entitled "Development and Flood Risk" (PPG25) outlines how flood risk issues should be addressed in regional planning guidance and Local Authorities' development plans. Bullen Consultants Ltd were commissioned by Corby Borough Council (CBC) in October 2003 to undertake a Strategic Flood Risk Assessment of Corby based on a Brief issued by the Borough Council. The Brief divided the study into two phases. Phase 1 involved the collation and evaluation of data and information relating to the hydrological and hydraulic aspects of flooding in Corby. Phase 2 of the study, based on the findings and conclusions of Phase 1, was to include the following main topics, including agreed work supplementary to the Brief: • Identifying and mapping the areas of flood risk over the whole of the Borough within the categories defined in Planning Policy Guidance Note 25 (PPG25). • Detailed flood risk assessments for a number of potential development areas within the Borough. (Ten specific development areas were subsequently defined by Catalyst Corby.) • Assessment of the effect on flood risk in Corby of large