T H A M E S A PPRAISAL PACKAGE ENV0000112C Reading and Caversham Flood Alleviation Scheme Appendix A: Options Appraisal Report Prepared for Environment Agency January 2019 CH2M Elms House, 43 Brook Green, London, W6 7EF United Kingdom Project Number: 683722CH Document History Reference Number: ENV0000112C-CH2-000-O00-RP-GEN-0004 Client Name: Environment Agency This document has been issued and amended as follows: Version Date Description Created By Verified By Approved By P01 15/05/2017 Draft P01.1 30/05/2017 Update of XXXXXXX - Draft only (internal) environmental sections P01.2 23/01/2018 Update of XXXXXXX XXXXXXX Draft only (internal) environmental XXXXXXX sections C01 02/02/2018 Approval of draft XXXXXXX XXXXXXX XXXXXXX Option Report P02 08/01/2019 Update of options for XXXXXXX XXXXXXX XXXXXXX OBC submission Contents 1 Introduction .................................................................................................................... 3 1.1 Background ................................................................................................................... 3 1.2 Approach & Purpose of this Report .............................................................................. 6 2 Business Case Objectives .................................................................................................. 7 2.1 Development of Objectives .......................................................................................... 7 2.2 Overall Objectives for the Business Case ...................................................................... 7 3 Appraisal Process ............................................................................................................. 9 3.1 Appraisal Process .......................................................................................................... 9 3.2 Assessment Criteria ...................................................................................................... 9 3.3 Stakeholder Cnsultation.............................................................................................. 15 4 Assessment of Short Listed Options ................................................................................ 17 4.1 Key Project Constraints ............................................................................................... 21 4.2 Option 1: Do Nothing .................................................................................................. 22 4.3 Option 2: Do Minimum ............................................................................................... 24 4.4 Option 3: Flood defences between Promenade Road and Christchurch Playing Fields .................................................................................................................................... 26 4.5 Option 4: Flood defences between Christchurch Playing Fields and Nire Road ......... 32 4.6 Option 5 Flood defences between Promenade Road and Nire Road ......................... 40 4.7 Option 6 Flood defences between Waterman Place and Reading Bridge .................. 45 4.8 Option 7 Flood defences between Promenade Road and Nire Road and between Waterman Place and Reading Bridge ......................................................................... 50 4.9 Option 8: Reading Bridge Bypass ................................................................................ 55 4.10 Cost Benefit Appraisal Summary Table ....................................................................... 59 4.11 Project Costs ............................................................................................................... 61 4.12 Appraisal Summary Table of Short List Options ......................................................... 62 4.13 Selection and Details of Preferred Option .................................................................. 67 5 Conclusion & Recommendations .................................................................................... 69 Appendix A – Long List of Options (From IA) Appendix B – Outline Design Drawings Appendix C – Do Nothing and Do Minimum Modelling Results Appendix D – Buildability Statement Appendix E – Carbon Modelling Tool Appendix F – Geotechnical Desk study & UXO Assessment Appendix G – Ground Investigation Report Appendix H – Project Costs Glossary of Terms AA Appropriate Assessment AEP Annual Exceedance Probability AONB Area of Outstanding Natural Beauty BCR Benefit Cost Ratio CFMP Catchment Flood Management Plan ECW Environmental Clerk of Works EQS Environmental Quality Standards ESE Early Supplier Engagement ESAP Environmental Site Appraisal Plan FBC Full Business Case FCERM-AG Flood and Coastal Risk Management Appraisal Guidance FRM Flood Risk Management FRMP Flood Risk Management Plan GI Ground Investigation HRA Habitat Regulations Assessment iBCR Incremental Benefit Cost Ratio LWS Local Wildlife Site NEAS National Environmental Assessment Service OBC Outline Business Case OM Outcome Measure PPG Pollution Prevention Guidelines PRoW Public Right(s) of Way RBC Reading Borough Council RFCC Regional Flood and Coastal Committee SAC Special Area of Conservation SoP Standard of Protection SPA Special Protection Area SSSI Site of Special Scientific Interest UWWT Urban Waste Water Treatment Directive UXO Unexploded Ordnance WFD Water Framework Directive Executive Summary This options appraisal report outlines the options assessment for the reduction of flood risk in Caversham, Reading, covering the north bank of the Thames. The south bank is considered separately. Business Case Objectives The objective of this business case was to identify an economically viable option through evaluation of costs and benefits that fully considers the effects of all sources of flood risk within the study area via an updated hydraulic model which also takes into account the Water Framework Directive (WFD) and other environmental considerations. Appraisal Process Short-listed options have been assessed against a wide range of criteria and subject to detailed hydraulic modelling and economic assessment as per Defra Flood and Coastal Erosion Risk Management Appraisal Guidance. Option assessment has also been informed by: • Site visits • Phase 1 Habitat Survey and targeted species surveys • Preliminary Environmental Information Report (PEIR) • Preliminary Water Framework Directive (WFD) assessment • Environmental Site Appraisal Plans • Indicative Landscape Plans • Option Plans • Carbon Modelling • Geotechnical desk study • Ground investigation works • Detailed hydraulic modelling • Advice and input from JacksonHyder as ESE supplier on the project. Assessment of Short-listed Options The six “Do Something” options assessed are: Option 3: Flood defences between Promenade Road and Christchurch Playing Fields, Option 4: Flood Defences between Christchurch Playing Fields and Nire Road, Option 5: A combination of Options 3 and 4, Option 6: Flood defences between Waterman Place and Reading Bridge (south bank), Option 7: A combination of Options 5 and 6, and Option 8: Bypass channel at George Street. Option 4 (Defences from Christchurch Playing Fields to Nire Road) has the highest iBCR, compared to Do Minimum, at 4.1. The iBCR of Option 7 (Defences from Promenade Road to Nire Road on the north bank and from Waterman Place and Reading Bridge on the south bank) compared to Do Minimum is 3.6. However, Option 7 also delivers the greatest value of OM1 benefits (at £137M) and OM2 properties (at 739). Based on appraisal of options against the assessment criteria as detailed in Section 4, detailed hydraulic modelling and economic assessment, Option 7 has been identified as the preferred option. This is based on the option delivering the project objectives in their entirety, including those of wider stakeholders, alongside the delivery of the greatest outcome measures available. 1 This option has a benefit cost ratio of 5.9 and a raw Partnership Funding Score of 34%. If the required partnership funding and/or project savings of £16.9M cannot be achieved, then the selection of Option 7 as the preferred option will be reviewed and either Option 4 or Option 5 will be progressed instead. Conclusions & Recommendations This options assessment has identified a likely preferred option which satisfies the four main categories of assessment (Technical, Environment, Economic and Social). The current raw Partnership Funding score (without contributions) for Option 7 is 34%. Contributions or savings of £16.9M are required to achieve an adjusted PF score of 100%. These costs contribute towards the Project Costs for Approval of £23.2M (including 50th percentile risk). A contribution of £5M of Local Levy has already been allocated to the project from Thames Regional Flood and Coastal Committee (RFCC). Opportunities to achieve project cost savings will be identified during the details appraisal stage, and additional economic benefits associated with road and infrastructure disruption will be assessed. The recommendation is to seek further engagement with stakeholders on options and funding and undertake required surveys before taking the project forward to the Full Business Case (FBC) stage. 2 1 Introduction 1.1 Background Purpose of document: This document forms an Appendix to the Outline Business Case (OBC) for the Caversham scheme. It provides supporting information on the appraisal of options undertaken for future flood risk management of the River Thames in Caversham. It should be read in conjunction with the main business case document and other supporting