Stoneleigh Park, Warwickshire Flood Risk & Drainage Assessment Version 1.1 FINAL May 2014 Kingswood House 80 Richardshaw Lane Pudsey Leeds West Yorkshire LS28 6BN ECUS Ltd FRA – Stoneleigh Park, Warwickshire DOCUMENT CONTROL SIGNATURE SHEET Report Title Stoneleigh Park, Warwickshire FRA Client ECUS Ltd. Date 9th May 2014 Produced by Emily Drake BSc Checked by Steven McAleer MEng MSc MCIWEM C.WEM CEnv Authorised by John Jepps BA MSc FORMAL REVISION HISTORY Version Date Release Status V0.1 04/02/14 Draft for internal review V0.2 06/02/14 Draft for client review V1.0 09/05/14 Final issue V1.1 09/05/14 Finall issue, update application area Formatted for Single / Double Sided Printing © Thomas Mackay Ltd i 13078_FRA_FINAL_V1-1_(Forissue).Docx May 2014 ECUS Ltd FRA – Stoneleigh Park, Warwickshire © Thomas Mackay Ltd ii 13078_FRA_FINAL_V1-1_(Forissue).Docx May 2014 ECUS Ltd FRA – Stoneleigh Park, Warwickshire CONTENTS Page Signature Sheet & Revision History i Contents ii List of Tables, Figures & Appendices iii 1 INTRODUCTION ................................................................................. 1 2 SITE DESCRIPTION AND BACKGROUND INFORMATION ........................ 2 2.1 SITE DESCRIPTION .................................................................................................... 2 2.2 DEVELOPMENT PROPOSAL ......................................................................................... 2 2.3 AVAILABLE DATA ....................................................................................................... 3 2.3.1 Design Drawings ........................................................................................................ 3 2.3.2 Environment Agency Flood Risk Map ........................................................................... 3 2.3.3 Strategic Flood Risk Assessment ................................................................................. 3 2.3.4 British Geological Survey Infiltration SuDS GeoReport .................................................. 3 3 FLOOD ZONE ..................................................................................... 4 3.1 FLOOD ZONE ............................................................................................................. 4 3.2 VULNERABILITY ......................................................................................................... 4 3.3 THE SEQUENTIAL TEST .............................................................................................. 4 4 FLOOD RISK AND CONSEQUENCES ..................................................... 5 4.1 HISTORICAL FLOODNG .............................................................................................. 5 4.2 ESTUARY / COASTAL FLOODING ................................................................................. 5 4.3 FLUVIAL FLOODING ................................................................................................... 5 4.4 GROUNDWATER FLOODING ....................................................................................... 5 4.5 SURFACE WATER FLOODING ...................................................................................... 5 4.6 FLOODING FROM MAN MADE STRUCTURES ................................................................ 6 4.6.1 Canals ....................................................................................................................... 6 4.6.2 Reservoirs ................................................................................................................. 6 5 SURFACE WATER MANAGEMENT ......................................................... 8 5.1 BACKGROUND ............................................................................................................ 8 5.2 SITE AREAS ............................................................................................................... 8 5.3 GREENFIELD RUNOFF RATE ....................................................................................... 8 5.4 SURFACE WATER RUNOFF AND MITIGATION .............................................................. 9 6 SUMMARY ........................................................................................ 10 6.1 RECOMMENDATIONS ............................................................................................... 10 © Thomas Mackay Ltd iii 13078_FRA_FINAL_V1-1_(Forissue).Docx May 2014 ECUS Ltd FRA – Stoneleigh Park, Warwickshire © Thomas Mackay Ltd iv 13078_FRA_FINAL_V1-1_(Forissue).Docx May 2014 ECUS Ltd FRA – Stoneleigh Park, Warwickshire LIST OF TABLES Table 1 Permeable and Impermeable Areas ........................................................................... 8 Table 2 Allowable Discharge Rates ........................................................................................ 8 Table 3 Storage at the site to mitigate against an increase in runoff volume ............................ 9 LIST OF FIGURES Figure 1 Site Location ............................................................................................................ 2 Figure 2 EA Flood Zone Map .................................................................................................. 4 Figure 3 Environment Agency Surface Water Flood Map .......................................................... 6 Figure 4 EA Risk of Flooding from Reservoirs Map ................................................................... 7 LIST OF APPENDICES Appendix A Topographic Survey Appendix B Site Layout Proposals Appendix C Environment Agency Data Appendix D BGS Infiltration SuDS GeoReport © Thomas Mackay Ltd v 13078_FRA_FINAL_V1-1_(Forissue).Docx May 2014 ECUS Ltd FRA – Stoneleigh Park, Warwickshire 1 INTRODUCTION Thomas Mackay Ltd has been instructed to provide a Flood Risk Assessment (FRA) for a proposed development near the village of Stoneleigh, Warwickshire. The development is for an Anaerobic Digestion Plant and associated infrastructure on land to the west of, and adjacent to Kings Wood, south of Stoneleigh Lane, Stoneleigh, Warwickshire. The land is currently greenfield, with the exception of an existing storage tank located in King’s Wood. A gas pipeline is also proposed to convey generated biogas to connect with the national gas grid near Crewe Farm to the south west of the ADP, or to the connection point to the north of the junction with the A46 with an electricity transmission line and ducting for heat transfer from the ADP to Stoneleigh Park to the south. The Environment Agency’s Flood Risk Map indicates that the site is within Flood Zone 1 (low probability of flooding from coastal and fluvial sources). However, as the development is over 1ha in size, an FRA is required in accordance with the National Planning Policy Framework. Consequently the FRA will focus on flood risk from surface water runoff and ensuring flood risk does not increase elsewhere as a result of the development. This assessment has been undertaken with reference to the National Planning Policy Framework1 (NPPF) and the Environment Agency Flood Risk Standing Advice v3.12. In brief this includes: Location plan Plans of the site including the existing site and the development proposals Site levels Proposals for surface water management An indication of surface water runoff rates An allowance for climate change Any other potential sources of flooding at the site This FRA aims to inform the client about the likely risk to the site and provide stakeholders with a description that flooding may have on the proposed development. 1 CLG (2012) National Planning Policy Framework 2 EA ( © Thomas Mackay Ltd 1 13078_FRA_FINAL_V1-1_(Forissue).Docx May 2014 ECUS Ltd FRA – Stoneleigh Park, Warwickshire 2 SITE DESCRIPTION AND BACKGROUND INFORMATION 2.1 SITE DESCRIPTION The site is located to the West of Stoneleigh, Warwickshire and is currently used for agriculture. The National Grid Reference for the site entrance is SP 32246 73254. A map of the location can be seen in Figure 1 below. Figure 1 Site Location The site is located in a rural area surrounded by agricultural fields to the south and east. The A46 is located on the north western boundary of the site, with the unclassified Stoneleigh Road to the North. The nearest dwelling to the site is Kingswood Farmhouse on the opposite side of the A46 road; Stoneleigh village is situated approximately 1km to the east of the site. Access to the site is via Stoneleigh Road on the northern boundary. The site is predominantly greenfield agricultural land, with the exception of an existing storage tank located in King’s Wood. The site ranges between 76 and 78mAOD in elevation. The land is gently sloping towards the A46 and a detailed topographic survey can be seen in Appendix A. 2.2 DEVELOPMENT PROPOSAL The proposal is to develop an Anaerobic Digestion Plant (ADP), and associated infrastructure on land to the west of, and adjacent to Kings Wood, south of Stoneleigh Lane, Stoneleigh, Warwickshire. Drawings in Appendix B show the location and boundary of the application site. In addition a gas pipeline is proposed to convey generated biogas to connect with the national gas grid near Crewe Farm to the south west of the ADP, or to the connection point to the north of the junction with the A46 and and an electricity transmission line and ducting for heat transfer from the ADP to Stoneleigh Park to the south. The application site for the proposed ADP is located in a rural setting and lies approximately 0.6 km to the north-west of Stoneleigh Village and approximately 0.8 km to the north of Stoneleigh