Lower Otter Restoration Project Exe Estuary Habitat Delivery Flood Risk Assessment ENVIMSW002045-CH2-000-000-RP-HY-0001 | P03 4 September 2020 Environment Agency ENVIMSW002045 Document Title C l i e n t N a m e Document history and status Revision Date Description Author Checked Reviewed Approved 01 Sept 2019 Draft for internal review ET SR PA TW P02 May 2020 Version for planning RH PA CG TW P03 Sept 2020 For Planning Submission RH PA CG TW Distribution of copies Revision Issue Date Issued to Comments approved issued Flood Risk Assessment Lower Otter Restoration Project Exe Estuary Habitat Delivery Project No: 684492CH Document Title: Flood Risk Assessment Document No.: ENVIMSW002045-CH2-000-000-RP-HY-0001 Revision: 3 Document Status: For Planning Submission Date: 2 July 2020 Client Name: Environment Agency Client No: ENVIMSW002045 Project Manager: Toby Wilson Author: Peter Andrews, Rachel Hopgood File Name: ENVIMSW002045-CH2_000-000-RP-HY_0001_new template.docx CH2M HILL United Kingdom Aperture @ Pynes Hill, Rydon Lane Exeter, EX2 5AZ United Kingdom T +44 (0)1392 269800 www.jacobs.com © Copyright 2019 CH2M HILL United Kingdom. The concepts and information contained in this document are the property of Jacobs. Use or copying of this document in whole or in part without the written permission of Jacobs constitutes an infringement of copyright. Limitation: This document has been prepared on behalf of, and for the exclusive use of Jacobs’ client, and is subject to, and issued in accordance with, the provisions of the contract between Jacobs and the client. Jacobs accepts no liability or responsibility whatsoever for, or in respect of, any use of, or reliance upon, this document by any third party. ENVIMSW002045-CH2-000-000-RP-HY-0001 i Flood Risk Assessment Contents 1. Introduction ............................................................................................................................................................ 4 1.1 Background ............................................................................................................................................................................... 4 1.2 Aims and Objectives............................................................................................................................................................... 4 1.3 Report Synopsis ....................................................................................................................................................................... 5 2. Site Setting .............................................................................................................................................................. 6 2.1 Site Location ............................................................................................................................................................................. 6 2.2 Description ................................................................................................................................................................................ 6 2.3 Hydrology .................................................................................................................................................................................. 7 2.4 Geology and Hydrogeology ............................................................................................................................................. 13 3. Proposed Development ..................................................................................................................................... 17 3.1 Project Vision ......................................................................................................................................................................... 17 3.2 Development Description ................................................................................................................................................. 17 3.3 Design Life .............................................................................................................................................................................. 18 3.4 Potential Receptors ............................................................................................................................................................. 18 4. UK Planning Policy / Guidance ........................................................................................................................ 29 4.1 National Planning Policy Framework (NPPF) ........................................................................................................... 29 4.1.1 General ..................................................................................................................................................................................... 29 4.1.2 Sequential Test ..................................................................................................................................................................... 30 4.1.3 Flood Risk and Vulnerability ............................................................................................................................................ 31 4.1.4 Exception Test ....................................................................................................................................................................... 31 4.2 Climate Change Allowances for Flood Risk Assessments .................................................................................... 31 4.2.1 Peak River Flow ..................................................................................................................................................................... 32 4.2.2 Peak Rainfall Intensity ....................................................................................................................................................... 32 4.2.3 Sea Level Allowance ........................................................................................................................................................... 32 4.2.4 Offshore wind speed and extreme wave height allowance ................................................................................. 33 4.3 Local Planning Policy ......................................................................................................................................................... 33 4.3.1 East Devon Local Plan ........................................................................................................................................................ 33 4.3.2 South Devon and Dorset Shoreline Management Plan ........................................................................................ 34 4.3.3 Phase 1/Phase 2a Surface Water Management Plan (Jacobs, 2012-2013) ............................................... 34 4.3.4 Strategic Flood Risk Assessment ................................................................................................................................... 34 4.3.5 Section 19 Historic Flood Investigation Reports ..................................................................................................... 36 4.3.5.1 Summer 2012 ....................................................................................................................................................................... 36 4.3.5.2 November 2012 ................................................................................................................................................................... 37 4.3.5.3 December 2013 - January 2014 ................................................................................................................................... 38 4.3.5.4 Summary ................................................................................................................................................................................. 38 5. Stakeholder Consultation ................................................................................................................................. 39 5.1 East Devon District Council .............................................................................................................................................. 39 5.2 Devon County Council........................................................................................................................................................ 39 ENVIMSW002045-CH2-000-000-RP-HY-0001 ii Flood Risk Assessment 5.2.1 Highway Authority ............................................................................................................................................................... 39 5.2.2 Public Rights of Way ........................................................................................................................................................... 40 5.2.3 Lead Local Flood Authority .............................................................................................................................................. 40 5.3 Environment Agency .......................................................................................................................................................... 40 5.4 Clinton Devon Estates ........................................................................................................................................................ 40 5.5 Western Power Distribution ............................................................................................................................................