Study of Interaction Between Broad Oak Reservoir and Richborough Connection Project South East Water and National Grid
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Study of interaction between Broad Oak Reservoir and Richborough Connection Project South East Water and National Grid Stage 1a Study B14000AG/BORStudy/801 Revision 2 28/04/2016 Document history and status Revision Date Description By Review Approved Ros Vincent & 0 18/06/2015 Draft John Gosden A J Smith Marcus Francis Ros Vincent 1 28/08/15 Stage 1a Final John Gosden A J Smith Chris Fisher Ros Vincent 2 28/04/16 Stage 1a Revised Final John Gosden A J Smith Chris Fisher Distribution of copies Revision Issue Date issued Issued to Comments approved South East Water & Issued as Draft for Comment 0 A J Smith 18th June 15 National Grid 28th August South East Water & 1 A J Smith Issued as Final Stage 1a Study Report 2015 National Grid South East Water & Issued as Revised Final Stage 1a Study Report - Minor text 2 A J Smith 28th April 16 National Grid changes (typos and clarifications) and risk methodology revised. Stage 1a Study Study of interaction between Broad Oak Reservoir and Richborough Connection project Project no: B14000AG Document title: Stage 1a Study Document No.: B14000AG/BORStudy/801 Revision: 2 Date: 28th April 2016 Client name: South East Water and National Grid Client no: Project manager: Alaistair Smith Author: Ros Vincent / Chris Fisher File name: B14000AG-BORStudy-801_Study of Interaction between Broad Oak Reservoir and RCP_Rev 2_Final for Issue.docx Jacobs U.K. Limited 1180 Eskdale Road Winnersh, Wokingham Reading RG41 5TU United Kingdom T +44 (0)118 946 7000 F +44 (0)118 946 7001 www.jacobs.com © Copyright 2016 Jacobs U.K. Limited. 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 report 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 report by any third party. Any advice, opinions, or recommendations within this document (a) should be read and relied upon only in the context of the document as a whole; (b) do not, in any way, purport to include any manner of legal advice or opinion; (c) are based upon the information made available to Jacobs at the date of this document and on current UK standards, codes, technology and construction practices as at the date of this document. It should be noted and it is expressly stated that no independent verification of any of the documents or information supplied to Jacobs has been made. No liability is accepted by Jacobs for any use of this document, other than for the purposes for which it was originally prepared and provided. Following final delivery of this document to the Client, Jacobs will have no further obligations or duty to advise the Client on any matters, including development affecting the information or advice provided in this document. B14000AG/BORStudy/801 – Rev 2 i Stage 1a Study Contents Executive Summary ............................................................................................................................. 1 1. Introduction ............................................................................................................................... 3 1.1 Purpose of Report ....................................................................................................................................... 4 1.2 Scope of work .............................................................................................................................................. 4 2. Study Approach and Baseline Data ........................................................................................ 6 2.1 Previous studies .......................................................................................................................................... 6 2.2 Topographic survey data ............................................................................................................................. 7 2.3 Geo-environmental assessment .................................................................................................................. 7 2.4 Geomorphology and Water Framework Directive ..................................................................................... 10 2.5 Aquatic Ecology ......................................................................................................................................... 12 2.6 Terrestrial ecology ..................................................................................................................................... 16 2.7 Landscape and visual ................................................................................................................................ 17 2.8 Cultural Heritage ........................................................................................................................................ 19 2.9 Hydrology .................................................................................................................................................. 20 2.10 Flood study ................................................................................................................................................ 22 2.11 Water resources modelling ........................................................................................................................ 23 3. Reservoir outline design ........................................................................................................ 27 3.1 Overall reservoir concept .......................................................................................................................... 27 3.2 Sarre Penn Diversion Outline design ........................................................................................................ 28 3.3 Dam right abutment outline design ............................................................................................................ 35 3.4 Permanent Access .................................................................................................................................... 40 3.5 Pipeline outline design .............................................................................................................................. 41 4. Outline environmental mitigation and enhancement for the reservoir .............................. 47 4.1 Stakeholder Requirements ........................................................................................................................ 47 4.2 WFD Compliance ...................................................................................................................................... 48 4.3 Terrestrial ecological: Potential Impacts ................................................................................................... 49 4.4 Aquatic Ecology: Potential Impacts ........................................................................................................... 50 4.5 Landscape and Visual: Potential Impacts ................................................................................................. 50 4.6 Cultural Heritage: Potential Impacts .......................................................................................................... 53 4.7 Indicative Mitigation Requirements ........................................................................................................... 54 4.8 Summary of Key Impacts and Mitigation Requirements ........................................................................... 58 5. Reservoir with the Richborough Connection ....................................................................... 63 5.1 Introduction ................................................................................................................................................ 63 5.2 Engineering ............................................................................................................................................... 63 5.3 Environmental Mitigation ........................................................................................................................... 65 6. Conclusions and Recommendations .................................................................................... 71 6.1 Introduction ................................................................................................................................................ 71 6.2 Key Findings .............................................................................................................................................. 71 6.3 Risks and Mitigation .................................................................................................................................. 73 B14000AG/BORStudy/801 – Rev 2 ii Stage 1a Study Appendix A. Aquatic Ecology Walkover Report Appendix B. Extended Phase 1 Habitat Survey Report Appendix C. Hydrological Study Appendix D. Geomorphological Study Appendix E. Environmental Constraints Report – Cultural Heritage Appendix F. Geo-environmental Desk Study Appendix G. Drawings & Concept Plan Appendix H. Pipeline Data Sources Summary B14000AG/BORStudy/801 – Rev 2 iii Stage 1a Study Executive Summary National Grid (NG) is following a programme to submit a Development Consent Order (DCO) application for the