Feasibility Report MDDP Tidal Water Resources Medway Group Abigail Nelson; Agilesh Singaraj; James Robinson; Jessica Hyland; Stavros Kylakos; Thomas Pughe TIDAL WATER RESOURCES | TEAM MEDWAY Table of Contents List of Figures ........................................................................................................................................ 1 List of Tables .......................................................................................................................................... 1 Executive Summary ........................................................................................................................ 1 Introduction .................................................................................................................................... 1 Scope of Work ................................................................................................................................ 2 Project Context and Goals .............................................................................................................. 3 Summary of Existing Conditions ................................................................................................... 4 Three Underlying Questions ........................................................................................................... 9 Operational Feasibility ................................................................................................................. 10 Best Configuration ........................................................................................................................ 11 How does this compare with other suggested schemes? .............................................................. 13 Conclusions and Next Steps ..................................................................................................... 17 Location of Weir ....................................................................................................................... 19 Abstraction Point ...................................................................................................................... 23 Mass Balance Check ................................................................................................................. 30 Safety Considerations and Statutory Issues .............................................................................. 38 Design Procedure for Movable Weirs ...................................................................................... 42 Design of Weir ......................................................................................................................... 44 Column Calculations ................................................................................................................ 52 Foundation Bearing Capacity ................................................................................................... 60 Slab Design ............................................................................................................................... 69 River Modelling........................................................................................................................ 73 Environmental Impact Assessment .......................................................................................... 92 Hydro-installation ................................................................................................................... 113 Construction Phasing .............................................................................................................. 141 Financial Analysis .................................................................................................................. 147 CONTENTS II TIDAL WATER RESOURCES | TEAM MEDWAY Risk Assessment ..................................................................................................................... 153 References .............................................................................................................................. 159 Appendix A Finance ....................................................................................................................... 166 Appendix B River Modelling .......................................................................................................... 169 Appendix C General Scheme Arrangement at Allington Weir ....................................................... 171 Appendix D Guide to Calculations and Relationships for Hydro Unit ........................................... 172 Appendix E Turbine Locations ....................................................................................................... 175 Appendix F Salinity graphs ............................................................................................................ 180 CONTENTS III List of Figures Figure 2-1:Location of River Medway ................................................................................................... 1 Figure 5-1: Rainfall Depths in England and Wales for the past 12 months (Environment Agency, 2014). ................................................................................................................................................................ 4 Figure 5-2: River discharge data and predictions for the future (Cloke, et al., 2010). ........................... 5 Figure 5-3 National Water Resource Availability (Environment Agency, 2000). ................................. 6 Figure 5-4 Current scheme in place at the River Medway (Beckett, 2014) ........................................... 7 Figure 5-5 The back pumping scheme that is currently at place for the Medway (Beckett, 2014) ........ 8 Figure 8-1 Downstream of Allington lock at low tide, the area is unnavigable ................................... 12 Figure 11-1: Proposed locations of weirs ............................................................................................. 19 Figure 11-2: Water levels at various locations along the River Medway for MHWS and MHWN ..... 20 Figure 11-3: Location of weir with lock ............................................................................................... 21 Figure 11-4: Revised location of weir with lock .................................................................................. 21 Figure 11-5: Proposed location of weir without lock ........................................................................... 22 Figure 12-1 - Medway River with Locations ....................................................................................... 23 Figure 12-2 - River Medway system diagram ...................................................................................... 24 Figure 12-3: Map showing the current abstraction point, water treatment works and new potential abstraction point. .................................................................................................................................. 25 Figure 12-4: Map showing Allington weir and position of Burham Water Treatment works ............. 26 Figure 12-5: Extract from South East Water planning drawing for new freshwater pipeline in Burham .............................................................................................................................................................. 27 Figure 13-1 River Medway Schematic for Mass Balance .................................................................... 31 Figure 13-2: Flow for a year for the River Medway at Teston and East Farleigh combined (Taken from Environment Agency, 2014) ................................................................................................................ 32 Figure 13-3: Flow for a year for the River Tesie at Stongbridge (Taken from Environment Agency, 2014) ..................................................................................................................................................... 33 Figure 13-4: Flow for a year for the River Beult at Stiebridge (Taken from Centre for Ecology & hydrology, 2013) .................................................................................................................................. 33 Figure 13-5: Flow for a year for the River Medway at Chafford (Taken from Centre for Ecology & Hydrology, 2013) ................................................................................................................................. 34 Figure 13-6: First Mass balance principle used .................................................................................... 34 Figure 13-7: Second Mass balance principle used ............................................................................... 35 Figure 15-1 Schematic of weir ............................................................................................................. 43 TIDAL WATER RESOURCES | TEAM MEDWAY Figure 16-1 Structural members of the radial gate (Erbisti, 2014) ....................................................... 45 Figure 16-2 Rear view of radial gate showing girder arrangement ...................................................... 46 Figure 16-3 Typical Arrangements of girders ...................................................................................... 46 Figure 16-4 Segment gate with 2 pairs of arms showing geometry ..................................................... 47 Figure 16-5 Loading on the vertical beams .........................................................................................