Castle Eaton AD Plant Extension and Upgrade
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Biomethane (Castle Eaton) Limited Castle Eaton AD Plant Extension and Upgrade Flood Risk Assessment 882120-R1(02)-FRA DECEMBER 2020 RSK GENERAL NOTES Project No.: 882120-R1(02)-FRA Site: Castle Eaton AD Plant upgrade and extension Title: Flood Risk Assessment Client: Biomethane (Castle Eaton) Limited Date: December 2020 Office: Wigan Status: Issue Technical Author K Jackson reviewer C Whittingham Signature Signature Date: December 2020 Date: December 2020 Project manager C Whittingham Project Director D Conway Signature Signature Date: December 2020 Date: December 2020 Date Reviewed Approved Issue No Version/Details Author issued by by - Internal Review 23.09.20 KJ CW CW 00 Draft for client comment 25.09.20 KJ CW DC 01 Updated draft 01.12.20 KJ CW DC 02 Issue 17.10.20 KJ CW DC RSK LDE Ltd (RSK) has prepared this report for the sole use of the client, showing reasonable skill and care, for the intended purposes as stated in the agreement under which this work was completed. The report may not be relied upon by any other party without the express agreement of the client and RSK. No other warranty, expressed or implied, is made as to the professional advice included in this report. Where any data supplied by the client or from other sources have been used, it has been assumed that the information is correct. No responsibility can be accepted by RSK for inaccuracies in the data supplied by any other party. The conclusions and recommendations in this report are based on the assumption that all relevant information has been supplied by those bodies from whom it was requested. No part of this report may be copied or duplicated without the express permission of RSK and the party for whom it was prepared. Where field investigations have been carried out, these have been restricted to a level of detail required to achieve the stated objectives of the work. RSKThis Environmentwork has been undertaken in accordance with the quality management system of RSK LDE Ltd. Castle Eaton Farm AD Plant extension and upgrade Flood Risk Assessment 882120-R1(02)-FRA CONTENTS 1 INTRODUCTION .............................................................................................................................. 1 1.1 Context ..................................................................................................................................... 1 1.2 Scope of work ........................................................................................................................... 2 2 SITE DESCRIPTION ........................................................................................................................ 4 2.1 Existing Site .............................................................................................................................. 4 2.2 Planning History ....................................................................................................................... 7 2.3 The Proposed Development ..................................................................................................... 9 3 LEGISLATION, POLICY AND GUIDANCE ................................................................................... 10 3.1 National Policy ........................................................................................................................ 10 3.2 Local Policy ............................................................................................................................ 11 3.3 Area Guidance ........................................................................................................................ 12 3.4 Site-specific consultation ........................................................................................................ 13 4 SOURCES OF FLOOD RISK ......................................................................................................... 16 4.1 Criteria .................................................................................................................................... 16 4.2 Flooding from rivers (fluvial flood risk) .................................................................................... 16 4.3 Flooding from the sea (tidal flood risk) ................................................................................... 17 4.4 Flooding from the land (overland pluvial flood risk) ................................................................ 18 4.5 Flooding from groundwater .................................................................................................... 19 4.6 Flooding from sewers ............................................................................................................. 20 4.7 Other sources of flooding ....................................................................................................... 21 5 FLOOD MITIGATION MEASURES ............................................................................................... 23 5.1 Overview ................................................................................................................................. 23 5.2 Overland flood flow ................................................................................................................. 23 5.3 Finished floor levels ................................................................................................................ 23 5.4 Safe access/egress ................................................................................................................ 23 5.5 Environmental Permit/Ordinary watercourse easement and consents .................................. 23 5.6 Groundwater ........................................................................................................................... 24 6 PLANNING CONTEXT ................................................................................................................... 25 6.1 Application of planning policy ................................................................................................. 25 6.2 Land use vulnerability ............................................................................................................. 25 6.3 Sequential Test ....................................................................................................................... 25 7 SURFACE WATER DRAINAGE STATEMENT ............................................................................. 27 7.1 Scope ..................................................................................................................................... 27 7.2 Proposed surface water drainage strategy ............................................................................ 27 8 CONCLUSIONS AND RECOMMENDATIONS ............................................................................. 29 RSK Environment i Castle Eaton Farm AD Plant extension and upgrade Flood Risk Assessment 882120-R1(02)-FRA APPENDICES APPENDIX A RSK GROUP SERVICE CONSTRAINTS APPENDIX B DEVELOPMENT PROPOSALS APPENDIX C SWINDON LLFA CORRESPONDENCE APPENDIX D CURRENT DRAINAGE ARRANGEMENT RSK Environment ii Castle Eaton Farm AD Plant extension and upgrade Flood Risk Assessment 882120-R1(02)-FRA 1 INTRODUCTION 1.1 Context 1.1.1 This Flood Risk Assessment (FRA) has been prepared on behalf of Biomethane (Castle Eaton) Limited (the ‘client’). The assessment is in support of the full planning submission for the upgrade and extension of an existing Anaerobic Digestion (AD) facility, located at Castle Eaton, SN6 6JX (the ‘site’). 1.1.2 The assessment has been prepared in accordance with the National Planning Policy Framework (NPPF)1 and its accompanying Planning Practice Guidance2, the Interim Code of Practice for Sustainable Drainage3, BS 8533-2011 Assessing and Managing Flood Risk in Development Code of Practice4, BS 8582:2013 Code of practice for surface water management for development sites5 and the Non-statutory technical standards for sustainable drainage systems6, with site-specific advice where relevant from the Environment Agency, the Lead Local Flood Authority (LLFA), the Local Planning Authority (LPA) and the client. 1.1.3 The NPPF sets out the criteria for development and flood risk by stating that inappropriate development in areas at risk of flooding should be avoided by directing development away from areas at highest risk, but where development is necessary, making it safe without increasing flood risk elsewhere. 1.1.4 The key definitions within the PPG are: • “Flood risk” is a combination of the probability and the potential consequences of flooding from all sources – including from rivers and the sea, directly from rainfall on the ground surface and rising groundwater, overwhelmed sewers and drainage systems, and from reservoirs, canals and lakes and other artificial sources; and • “Areas at risk of flooding” means areas at risk from all sources of flooding. For fluvial (river) and sea flooding, this is principally land within Flood Zones 2 and 3. It can also include an area within Flood Zone 1 which the Environment Agency has notified the local planning authority as having critical drainage problems. 1 Ministry of Housing, Communities and Local Government, ‘National Planning Policy Framework’, February 2019. 2 Ministry of Housing, Communities and Local Government, ‘Planning Practice Guidance - Flood Risk and Coastal Change, ID 7’, March 2014. http://planningguidance.planningportal.gov.uk/blog/guidance/flood-risk-and-coastal- change/ 3 DEFRA, ‘Interim Code of Practice for Sustainable Drainage