Chapter 9: Road drainage and the water environment

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2.2.3 PPS25 Sequential Test The Sequential Test is used to examine the possibility of relocating development in areas found to be at medium and high probability of flooding from rivers and the sea to areas of low probability. The definition of low, medium and high probability flood risk areas is determined in PPS25 and is shown below Table 1. Flood Zone 1 Flood Zone 2 Flood Zone 3a Flood Zone 3b Low Probability Medium Probability High Probability The Functional Floodplain This zone comprises land assessed as having less than 1 in 1000 annual probability of river or sea flooding in any year (1% AEP) or a 1 in 200 or greater annual probability of flooding from the sea (>0.5% AEP) in any year. This zone comprises land where water has to flow or be stored in times of flood. Strategic Flood Risk Assessments (SFRA) should identify this Flood Zone (land which would flood with an annual probability of 1 in 20 (5% AEP) or greater in any year or is designed to flood in an extreme (0.1% AEP) flood or at another probability to be agreed between the LPA and the Environment Agency, including water conveyance routes). Table 1: Definition of Flood Zones (from PPS25 Table D1) If areas at lower flood risk are not available or appropriate, then vulnerability of the proposed development to the effects of flooding are considered. Within PPS25, the vulnerability of different types of development is given. These are shown in the table below: Essential Infrastructure Highly Vulnerable More Vulnerable Less Vulnerable Water Compatible Essential transport infrastructure (including mass evacuation routes) that has to cross the area at risk, and strategic utility infrastructure, including electricity generating power stations and grid and primary substations. Police stations, ambulance stations and fire stations and command centres and telecommunications installations required to be operational during flooding; emergency dispersal points; basement dwellings; caravans, mobile homes and park homes intended for permanent residential use; installations requiring hazardous substances consent. Hospitals; residential institutions; dwelling houses; pubs, clubs, hotels; health centres, nurseries, schools; landfill and sites for hazardous waste; sites used for holiday, short let caravans and camping. Retail, offices, warehouses, workshops, leisure; agriculture; nonhazardous waste treatment; mineral working; water treatment plants; sewage treatment plants. Flood control infrastructure; water transmission infrastructure; docks, marinas, wharves; navigation facilities; MOD defence installations; ship building; water based recreation; lifeguard stations; amenity open spaces and sand and gravel workings. Table 2: Development Vulnerability (as defined in PPS25 Table D2) 2 AEP: Annual Exceedance Probability 4
When the both the ‘Flood Zone’ and ‘flood vulnerability’ of flooding have been identified, compatibility of the proposed development is confirmed in-line with Table 3 (Table D3 in PPS25). The requirements of the Exception Test are as follows: a) it must be demonstrated that the development provides wider sustainability benefits to the community that outweigh flood risk, informed by a SFRA where one has been prepared. If the Development Plan Document (DPD) has reached the ‘submission’ stage the benefits of the development should contribute to the Core Strategy‘s Sustainability Appraisal; b) the development should be on developable previously-developed land or, if it is not on previously developed land, that there are no reasonable alternative sites on developable previously-developed land; c) a FRA must demonstrate that the development will be safe, without increasing flood risk elsewhere, and, where possible, will reduce flood risk overall. Flood Risk Vulnerability Classification Zone 1 Essential Infrastructure Water Compatible Highly Vulnerable More Vulnerable Less Vulnerable Flood Zone Zone 2 Zone 3a Exception Test required Exception Test required Exception Test required Zone 3b Exception Test required Development is appropriate Development should not be permitted Table 3: Flood Risk Vulnerability and Flood Zone ‘Compatibility’ (Table D3 in PPS25). 2.3 Harborough Strategic Flood Risk Assessment In accordance with PPS25, Harborough District Council commissioned Scott Wilson to undertake a Strategic Flood Risk Assessment (SFRA) to inform the LDF. At the time of writing the Harborough SFRA was still in preparation and had not been issued. The recommendations and aspirations of the SFRA will therefore not be considered in this FRA. 5
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M1 Junction 19 Improvement Environm
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M1 JUNCTION 19 IMPROVEMENT ENVIRONM
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Page 40 and 41: M1 JUNCTION 19 IMPROVEMENT ENVIRONM
Page 71 and 72: Appendix A - Pollution and Spillage
Page 73: Method D - Assessment of Pollution
Page 78 and 79: Groundwater: Hydrocarbons Hydrogeol
Page 83 and 84: Non Technical Summary Skanska Const
Page 85 and 86: Contents 1 Introduction 1 1.1 Overv
Page 87 and 88: 1 Introduction 1.1 Overview Jacobs
Page 89: 2 Policy Review 2.1 Planning Contex
Page 93 and 94: 3 Flood Risk to the Proposed Develo
Page 95 and 96: 3.2 Fluvial Flooding - Ordinary Wat
Page 97 and 98: Major earthworks affecting surface
Page 99 and 100: 3.7 Flooding from Infrastructure Fa
Page 101 and 102: 3.9 Summary of Risks to Site Table
Page 103 and 104: 4 Impacts of the Proposed Developme
Page 105 and 106: 4.6 Summary of Flood Impacts from D
Page 107 and 108: 5 Proposed Mitigation Measures 5.1
Page 109 and 110: The extents of this problem are cur
Page 111 and 112: 5.7 Summary of Recommended Mitigati
Page 113 and 114: 6 Residual Risks The level of flood
Page 115 and 116: 7 PPS25 Sequential and Exception Te
Page 117 and 118: 8 Conclusion The M1 Junction 19 Imp
Page 119 and 120: Appendix A Existing Layout, Environ
Page 127 and 128: Appendix B Contractor’s Proposals
Page 129 and 130: Appendix C Hydrogeological Assessme
Page 131 and 132: Memorandum Fairbairn House, Ashton
Page 133 and 134: Memorandum (Continued) Page 3 of 6
Page 135 and 136: Memorandum (Continued) Page 5 of 6
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Appendix D Volume Distribution for
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Floodplain compensation area - elev
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Depth Bands (m) TOTAL (m³) Area Re
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Chapter 9: Road drainage and the water environment

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