GARD response to Thames Water’s Consultation on Draft Water Resources Management Plan 2019 29th April 2018 GARD Rivendell 142 The Causeway Steventon Oxfordshire OX13 6SJ www.abingdonreservoir.org [email protected] Contents Summary ......................................................................................................................... 1 1. Introduction ........................................................................................................... 15 1.1 Scope of response ..................................................................................................... 16 1.2 Availability of information and transparency ............................................................. 17 1.3 The effectiveness of stakeholder engagement ........................................................... 18 1.4 Over-dependence on Atkins’ stochastic river flow data ............................................. 19 2. Supply/Demand balance and deficit forecasts......................................... 22 2.1 Population Forecasting Issues. ................................................................................... 24 2.2 Per Capita Consumption ............................................................................................ 30 2.3 Existing deployable output and allowance for climate change ................................... 32 2.4 Uncertainty in the deficit forecast ............................................................................. 36 3. Leakage and demand management options .............................................. 39 3.1 Introduction .............................................................................................................. 41 3.2 Leakage ..................................................................................................................... 41 3.3 Demand Management ............................................................................................... 49 3.4 Non-household water use ......................................................................................... 56 4. Teddington Direct River Abstraction ........................................................... 58 4.1 Scope and Deployable Output ................................................................................... 59 4.2 Need for additional treatment ................................................................................... 66 4.3 Environmental and Other Impacts ............................................................................. 66 4.4 Cost Estimates ........................................................................................................... 67 4.5 Conclusion ................................................................................................................. 68 5. Effluent reuse options ........................................................................................ 69 5.1 Introduction – options and locations ......................................................................... 70 5.2 Deephams and Beckton options ................................................................................ 71 5.3 Water level impact on the Tideway ........................................................................... 76 5.4 Inter-connecting works and reuse issues ................................................................... 78 6. Desalination options ........................................................................................... 81 6.1 The potential for desalination generally .................................................................... 82 6.2 Sites considered for desalination ............................................................................... 84 7. Inter-regional transfer options ...................................................................... 86 7.1 The strategic need to transfer water to the South East .............................................. 87 7.2 Unsupported Severn-Thames transfer ....................................................................... 89 7.3 The need for water treatment ................................................................................... 95 7.4 Severn-Thames transfer supported by Vyrnwy reservoir ........................................... 96 7.5 Transfer losses in the River Severn .......................................................................... 107 7.6 Severn-Thames transfer supported by Severn Trent or DCWW ................................ 109 7.7 Use of the Cotswold Canal ....................................................................................... 110 7.8 Transfers by the Oxford Canal ................................................................................. 110 7.9 Environmental assessment ...................................................................................... 111 8. Abingdon reservoir .......................................................................................... 112 8.1 Introduction and overview ...................................................................................... 114 8.2 Deployable output and emergency storage .......................................................... 117 8.3 Environmental Assessment ...................................................................................... 121 8.4 Archaeology and Cultural Heritage .......................................................................... 125 8.5 Landscape and visual amenity ................................................................................. 127 8.6 Flooding impacts ..................................................................................................... 130 8.7 Cost estimates ......................................................................................................... 133 9. Resilience to severe droughts ...................................................................... 134 9.1 Resilience design criteria ......................................................................................... 135 9.2 Abingdon reservoir .................................................................................................. 138 9.3 Severn-Thames transfer options .............................................................................. 140 9.4 Teddington DRA, effluent reuse and desalination options ....................................... 141 10. Thames Valley zones ..................................................................................... 142 10.1 Supply demand balance ......................................................................................... 143 10.2 Options for Thames Valley zones ........................................................................... 145 10.3 The needs of SWOX zone ....................................................................................... 147 11. Programme Appraisal................................................................................... 150 11.1 Overview ............................................................................................................... 152 11.3 Review of application of Strategic Environmental Assessment............................... 156 11.4 Comparison of options other than cost and Environmental Impact ....................... 159 11.5 Assessment of alternative programmes ................................................................. 162 11.6 Programme option comparisons ............................................................................ 165 Appendix A – Teddington DRA deployable output calculations Appendix B – Inter-regional transfer support documents Appendix C – GARD reassessed SEA for 150 Mm3 Abingdon reservoir (submitted separately in digital format) Figures Figure 2-1: GARD population estimates overlaid on TW estimates ...................................... 28 Figure 2-2: London base case deployable output modelled using the "old" LTCD ................ 33 Figure 2-3: Changes in Teddington natural flows WARMS1 to WARMS2 ............................. 34 Figure 2-4: Frequency and severity of droughts affecting London's water supplies ............. 36 Figure 2-5: Forecast London supply deficit .......................................................................... 37 Figure 3-1: Comparison of water company leakage reduction plans .................................... 48 Figure 3-2: Thames Water planned meter penetration........................................................ 52 Figure 3-3: Planned reduction in pcc in London and Thames Valley ..................................... 55 Figure 3-4: Forecast ppc reduction of other water companies ............................................. 55 Figure 3-5: Forecast non-household demand in TW regions ................................................ 56 Figure 4-1: Deficit in water available for abstraction in droughts ......................................... 61 Figure 4-2: Effect of adding DRA to base case demand in 1933/34 drought ......................... 63 Figure 5-1: Salinity across the Thames Tideway ................................................................... 77 Figure 7-1: Deficit and transfer regions in England and Wales ............................................. 87 Figure 7-2: Stochastic and historic flow duration in Sep-Oct at Teddington and Deerhurst .. 91 Figure 7-3: Yield v return period for Unsupported STT......................................................... 92 Figure 7-4: Performance of 300 Ml/d unsupported transfer in 1921/22 and 1933/34 ......... 94