Crossrail Line 1 Assessment of Water Resource Impacts Technical Report

Transcription

1 Cross London Rail Links 1 Butler Place London SW1H 0PT United Kingdom Crossrail Line 1 Assessment of Water Resource Impacts Technical Report Volume I Main Report Demeter House Station Road Cambridge CB1 2RS United Kingdom Tel : +44 (0) Fax : +44 (0)

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3 Assessment of Water Resource Impacts Technical report Volume 1 Main Report 1E0321-1E REVISION HISTORY Final February 2005 C Wilson S Jensen C Jones J Pavey J van Wonderen Final issue Rev Date Prepared Review Approved Description 1, Butler Place LONDON SW1H 0PT Tel: Fax:

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5 List of Contents Page Volume 1 Main Report 1 Background and Introduction Introduction to Crossrail Objectives of Crossrail Overview of Engineering Works Methodology for Water Resources Assessment Introduction Scoping Potential Impacts Definition of Scope Inventory of Resources and Receptors Consultation Establishment of Baseline Overview Surface Water Hydrology Groundwater Hydrogeology Prediction of Impacts Overview Surface Water Groundwater Evaluation of Impacts Environmental Baseline and Assessment of Impacts: Route Wide Scope Guidelines Generic Mitigation Measures - General Site Operations Impacts on Groundwater Construction Works Requiring Dewatering New Structures in the Shallow and Deep Aquifers Modifications to Railway Usage Railway Systems Infrastructure and Railway Operations Grout Shafts Impacts on Surface Water Disposal of Dewatering Effluent Works Affecting Surface Water Runoff Additional Monitoring of the Water Environment 4-11 Contents page rev101.doc i

6 5 Environmental Baseline and Assessment of Impacts Western Route Section Overview of Western Route Section Sources of Information Baseline Information Western Route Section Introduction Geology and Hydrogeology Surface Water Designated Nature Conservation Sites Impacts and Mitigation Western Route Section Potential Impacts on Groundwater and Generic Mitigation Potential Impacts on Surface Water and Generic Mitigation Route Window W25 Maidenhead Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window W24 Maidenhead Railway Bridge Scheme Description Additional Description in Relation to Water Resources Baseline Data Impact Assessment Route Window W23 Taplow Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window W22 Lent Rise Scheme Description Baseline Data Impact Assessment Route Window W21 Burnham Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window W20 Dover Road and Leigh Road Bridges Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window W19 Stoke Poges Lane Bridge Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment 5-33 ii Contents page rev101.doc

7 5.12 Route Window W18 Slough Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window W17 Middlegreen Road, St Mary s Road & Trenches Bridges Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window W16 Langley Station Scheme Description Baseline Data Impact Assessment Route Window W15 Dog Kennel Bridge Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window W14 Iver Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window W13 West Drayton Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window W12 Kingston Lane Bridge and Old Stockley Road Bridges Scheme Description Baseline Data Impact Assessment Route Window W11 Stockley Flyover Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window W10 Hayes & Harlington Station Scheme Description Baseline Data Impact Assessment Route Window W9 Southall West Sidings Scheme Description 5-71 iii Contents page rev101.doc

8 Baseline Data Impact Assessment Route Window W8 Southall Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window W7 Hanwell Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window W6 West Ealing Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window W5 Ealing Broadway Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window W4 Acton Main Line Station & Yard Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window W3 Old Oak Common Depot Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window W2 Canal Way Scheme Description Baseline Data Impact Assessment Route Window W1 Portobello Junction Scheme Description Baseline Data Impact Assessment Route Windows H1 to H Summary of Significant Impacts and Assessment Western Route Section 5-99 Contents page rev101.doc iv

9 6 Environmental Baseline and Assessment of Impacts Central Route Section Overview of Route Section Sources of Information Baseline Information Central Section Introduction Geology and Hydrogeology Surface Water Designated Nature Conservation Sites Impacts and Mitigation Central Section Potential Impacts on Groundwater and Generic Mitigation Potential Impacts on Surface Water and Generic Mitigation Route Window C1 - Royal Oak Portal Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window C2 Paddington Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window C3 Hyde Park & Park Lane Shafts Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window C4 Bond Street Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window C5 Tottenham Court Road Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window C6 Farringdon Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window C7 Liverpool Street Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data 6-56 v Contents page rev101.doc

10 Impact Assessment Route Window C8 Whitechapel Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window C8A Mile End Conveyor Corridor Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window C9 Stepney Green Shafts Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window C10 Lowell Street Shaft Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window C11 Isle of Dogs Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window C12 Mile End Park & Eleanor Street Shafts Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window C13 Pudding Mill Lane Portal Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window C13A Abbey Mills Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Summary of Significant Impacts and Assessment Central Route Section Contents page rev101.doc vi

11 7 Environmental Baseline and Assessment of Impacts North East Route Section Overview of Route Section Sources of Information Baseline Information North East Route Section Introduction Geology and Hydrogeology Surface Water Designated Nature Conservation Sites Impacts and Mitigation North East Route Section Potential Impacts on Groundwater and Generic Mitigation Potential Impacts on Surface Water and Generic Mitigation Route Window NE1 Stratford Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window NE2 Forest Gate Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window NE3 Manor Park Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window NE4 Ilford Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window NE5 Seven Kings Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window NE6 Goodmayes Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window NE7 Chadwell Heath Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data 7-36 vii Contents page rev101.doc

12 Impact Assessment Route Window NE8 Romford Depot (West) Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window NE9 Romford Station and Depot (East) Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window NE10 Gidea Park Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window NE11 Gidea Park Stabling Sidings Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window NE12 Harold Wood Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window NE13 LB Havering/Brentwood DC Boundary Scheme Description Baseline Data Impact Assessment Route Window NE14 Brook Street Scheme Description Baseline Data Impact Assessment Route Window NE15 Brentwood Station Scheme Description Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window NE16 Thrift Wood Scheme Description Baseline Data Impact Assessment Route Window NE17 Shenfield Station Scheme Description 7-68 Contents page rev101.doc viii

13 Contents page rev101.doc Additional Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Summary of Significant Impacts and Assessment - Stratford to Shenfield Route Window R1 Pitsea Sidings Scheme Description Baseline Data Impact Assessment Environmental Baseline and Assessment of Impacts South East Route Section Overview of Route Section Sources of Information Baseline Information South East Route Section Introduction Geology and Hydrogeology Surface Water Designated Nature Conservation Sites Impacts and Mitigation South East Route Section Potential Impacts on Groundwater and Generic Mitigation Potential Impacts on Surface Water and Generic Mitigation Route Window SE1 Blackwall Way & Limmo Peninsula Shafts Scheme Description Additional Scheme Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window SE2 Custom House Station Scheme Description Additional Scheme Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window SE3 Connaught Tunnel Scheme Description Additional Scheme Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window SE4 North Woolwich Portal & Thames Tunnel Scheme Description Additional Scheme Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window SE5 Arsenal Way Shaft 8-50 ix

14 8.9.1 Scheme Description Additional Scheme Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window SE6 Plumstead Portal Scheme Description Additional Scheme Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window SE6A Manor Wharf Scheme Description Additional Scheme Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window SE7 Church Manorway Bridge Scheme Description Additional Scheme Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Route Window SE8 Abbey Wood Station Scheme Description Additional Scheme Description Assumed for Water Resources Assessment Baseline Data Impact Assessment Summary of Significant Impacts and Assessment South East Route Section Cumulative Impacts and Mitigation Measures Principal Findings and Summary Glossary References 12-1 Contents page rev101.doc x

15 Tables Table 3.1: Impact Likelihood Definitions 3-7 Table 3.2: Impact Categorisation 3-7 Table 4.1: Guidelines for Prevention of Pollution from Construction Sites 4-1 Table 5.1: Sources of Data 5-2 Table 5.2: Stratigraphy- Western Route Section 5-3 Table 5.3: Summary of Baseline - Route Window W Table 5.4: Surface Water Discharges Route Window W Table 5.5: Summary of Baseline - Route Window W Table 5.6: Summary of Baseline - Route Window W Table 5.7: Summary of Baseline - Route Window W Table 5.8: Summary of Baseline - Route Window W Table 5.9: Summary of Baseline - Route Window W Table 5.10: Summary of Baseline - Route Window W Table 5.11: Summary of Baseline - Route Window W Table 5.12: Summary of Baseline - Route Window W Table 5.13: Summary of Baseline - Route Window W Table 5.14: Summary of Baseline - Route Window W Table 5.15: Summary of Baseline - Route Window W Table 5.16: Summary of Baseline - Route Window W Table 5.17: Summary of Baseline - Route Window W Table 5.18: Summary of Baseline - Route Window W Table 5.19: Summary of Baseline - Route Window W Table 5.20: Summary of Baseline - Route Window W Table 5.21: Summary of Baseline - Route Window W Table 5.22: Summary of Baseline - Route Window W Table 5.23: Summary of Baseline - Route Window W Table 5.24: Summary of Baseline - Route Window W Table 5.25: Summary of Baseline - Route Window W Table 5.26: Summary of Baseline - Route Window W Table 5.27: Summary of Baseline - Route Window W Table 5.28: Summary of Baseline - Route Window W Table 5.29: Significant Temporary and Permanent Impacts Western Route Section 5-99 Table 6.1: Main Construction Works in the Central Section 6-3 Table 6.2: Sources of Data 6-8 Table 6.3: Stratigraphy 6-10 Table 6.4: Description of Facies Presented in the Lambeth Group 6-13 Table 6.5: Lost Rivers/Sewers Crossed by the Crossrail Alignment 6-18 Table 6.6: Thames Flood Levels and Defences 6-19 Table 6.7: Summary of Baseline - Route Window C Table 6.8: Summary of Baseline - Route Window C Table 6.9: Summary of Baseline - Route Window C Table 6.10: Summary of Baseline - Route Window C Table 6.11: Summary of Baseline - Route Window C Table 6.12: Summary of Baseline - Route Window C xi Contents page rev101.doc

16 Table 6.13: Summary of Baseline - Route Window C Table 6.14: Summary of Baseline - Route Window C Table 6.15: Summary of Baseline - Route Window C8A 6-65 Table 6.16: Summary of Baseline - Route Window C Table 6.17: Summary of Baseline Route Window C Table 6.18: Summary of Baseline - Route Window C Table 6.19: Modelled Drawdown at Existing Abstraction Boreholes 6-84 Table 6.20: Summary of Baseline - Route Window C Table 6.21: Summary of Baseline - Route Window C Table 6.22: Summary of Baseline - Route Window C13A Table 7.1: Main Elements of the Project in the North East Route Section (route windows with major works are highlighted) 7-2 Table 7.2: Sources of Data North East Route Section 7-4 Table 7.3: Stratigraphy 7-5 Table 7.4: Modelled Flood Levels 7-11 Table 7.5: Summary of Baseline - Route Window NE Table 7.6: Summary of Baseline - Route Window NE Table 7.7: Summary of Baseline - Route Window NE Table 7.8: Summary of Baseline - Route Window NE Table 7.9: Summary of Baseline - Route Window NE Table 7.10: Summary of Baseline - Route Window NE Table 7.11: Summary of Baseline - Route Window NE Table 7.12: Summary of Baseline - Route Window NE Table 7.13: Geological Sequence at Romford Gas Works 7-47 Table 7.14: Summary of Baseline - Route Window NE Table 7.15: Summary of Baseline - Route Window NE Table 7.16: Summary of Baseline Route Window NE Table 7.17: Summary of Baseline - Route Window NE Table 7.18: Summary of Baseline - Route Window NE Table 7.19: Summary of Baseline - Route Window NE Table 7.20: Summary of Baseline - Route Window NE Table 7.21: Summary of Baseline - Route Window NE Table 7.22: Summary of Baseline - Route Window NE Table 7.23: Summary of Baseline - Route Window R Table 8.1: Main Elements of the Scheme within the South East Route Section (Route windows with major works are highlighted) 8-2 Table 8.2: Sources of Data South East Route Section 8-3 Table 8.3: Stratigraphy South East Route Section 8-5 Table 8.4: Description of Facies Presented in the Lambeth Group 8-8 Table 8.5: Thames Flood Levels and Defences 8-15 Table 8.6: Summary of Baseline - Route Window SE Table 8.7: Summary of Baseline - Route Window SE Table 8.8: Summary of Baseline - Route Window SE Table 8.9: Geological Data for Warren Lane Shaft 8-45 Table 8.10: Summary of Baseline - Route Window SE Table 8.11: Summary of Baseline - Route Window SE Table 8.12: Summary of Baseline - Route Window SE Contents page rev101.doc xii

17 Table 8.13: Summary of Baseline - Route Window SE6A 8-61 Table 8.14: Geological Strata Thicknesses (matd) 8-65 Table 8.15: Summary of Baseline - Route Window SE Table 8.16: Summary of Baseline - Route Window SE Contents page rev101.doc xiii

18 Figures Figure 2.1: Overview of Crossrail Route 2-2 Figure 5.1: Western Route Section Alignment 5-1 Figure 5.2: Route Window W25 Maidenhead Station 5-13 Figure 5.3: Route Window W24 Maidenhead Railway Bridge 5-17 Figure 5.4: Route Window W23 Taplow Station 5-21 Figure 5.5: Route Window W22 Lent Rise 5-23 Figure 5.6: Route Window W21 Burnham Station 5-26 Figure 5.7: Route Window W20 Dover Road and Leigh Road Bridges 5-28 Figure 5.8: Route Window W19 Stoke Poges Lane Bridge 5-31 Figure 5.9: Route Window W18 Slough Station 5-35 Figure 5.10: Route Window W17 Middlegreen Road, St Mary s Road & Trenches Bridges 5-39 Figure 5.11: Route Window W16 Langley Station 5-42 Figure 5.12: Route Window W15 Dog Kennel Bridge 5-45 Figure 5.13: Route Window W14 Iver Station 5-50 Figure 5.14: Route Window W13 West Drayton Station 5-53 Figure 5.15: Route Window W12 - Kingston Lane Bridge and Old Stockley Road Bridges 5-59 Figure 5.16: Route Window W11 Stockley Flyover 5-63 Figure 5.17: Route Window W10 Hayes & Harlington Station 5-68 Figure 5.18: Route Window W9 Southall West Sidings 5-72 Figure 5.19: Route Window W8 Southall Station 5-74 Figure 5.20: Route Window W7 Hanwell Station 5-77 Figure 5.21: Route Window W6 West Ealing Station 5-80 Figure 5.22: Route Window W5 Ealing Broadway Station 5-83 Figure 5.23: Route Window W4 Acton Main Line Station & Yard 5-85 Figure 5.24: Route Window W3 Old Oak Common Depot 5-90 Figure 5.25: Route Window W2 - Canal Way 5-93 Figure 5.26: Route Window W1 Portobello Junction 5-96 Figure 5.27: Route Windows H1 to H Figure 6.1: Central Section Route Alignment 6-1 Figure 6.2: Route Window C1 Royal Oak Portal 6-27 Figure 6.3: Route Window C2 Paddington Station 6-32 Figure 6.4: Route Window C3 Hyde Park & Park Lane Shafts 6-35 Figure 6.5: Route Window C4 Bond Street Station 6-40 Figure 6.6: Route Window C5 Tottenham Court Road Station 6-44 Figure 6.7: Route Window C6 Farringdon Station 6-49 Figure 6.8: Route Window C7 Liverpool Street Station 6-54 Figure 6.9: Route Window C8 Whitechapel Station 6-59 Figure 6.10: Route Window C8A Mile End Conveyor Corridor 6-64 Figure 6.11: Route Window C9 Stepney Green Shafts 6-67 Figure 6.12: Route Window C10 Lowell Street Shaft 6-72 Figure 6.13: Route Window C11 Isle of Dogs Station 6-78 Figure 6.14: Route Window C12 Mile End Park & Eleanor Street Shafts 6-89 Figure 6.15: Route Window C13 Pudding Mill Lane Portal 6-95 Figure 6.16: Bow Back Rivers xiv Contents page rev101.doc

19 Figure 6.17: Route Window C13A Abbey Mills Figure 7.1: North East Route Section Alignment 7-1 Figure 7.2: Route Window NE1 Stratford Station 7-16 Figure 7.3: Route Window NE2 Forest Gate Station 7-19 Figure 7.4: Route Window NE3 Manor Park Station 7-22 Figure 7.5: Route Window NE4 Ilford Station 7-25 Figure 7.6: Route Window NE5 Seven Kings Station 7-29 Figure 7.7: Route Window NE6 Goodmayes Station 7-32 Figure 7.8: Route Window NE7 Chadwell Heath Station 7-35 Figure 7.9: Route Window NE8 Romford Depot (West) 7-38 Figure 7.10: Route Window NE9 Romford Station and Depot (East) 7-44 Figure 7.11: Route Window NE10 Gidea Park Station 7-50 Figure 7.12: Route Window NE11 Gidea Park Stabling Sidings 7-53 Figure 7.13: Route Window NE12 Harold Wood Station 7-57 Figure 7.14: Route Window NE13 LB Havering/Brentwood DC Boundary 7-60 Figure 7.15: Route Window NE14 Brook Street 7-62 Figure 7.16: Route Window NE15 Brentwood Station 7-65 Figure 7.17: Route Window NE16 Thrift Wood 7-67 Figure 7.18: Route Window NE17 Shenfield Station 7-69 Figure 7.19: Route Window R1 Pitsea Sidings 7-73 Figure 8.1: South East Route Section 8-1 Figure 8.2: Marsh Dykes 8-14 Figure 8.3: Route Window SE1 Blackwell Way & Limmo Peninsula Shafts 8-22 Figure 8.4: Route Window SE2 Custom House Station 8-30 Figure 8.5: Route Window SE3 Connaught Tunnel 8-36 Figure 8.6: Route Window SE4 North Woolwich Portal & Thames Tunnel 8-41 Figure 8.7: Section along Thames Crossing 8-44 Figure 8.8: Route Window SE5 Arsenal Way Shaft 8-51 Figure 8.9: Route Window SE6 Plumstead Portal 8-55 Figure 8.10: Route Window SE6A Manor Wharf 8-60 Figure 8.11: Route Window SE7 Church Manorway Bridge 8-63 Figure 8.12: Geology between Plumstead Portal and Abbey Wood Station 8-65 Figure 8.13: Route Window SE8 Abbey Wood Station 8-68 Contents page rev101.doc xv

20 List of Contents Page Volume 2 Appendices Appendix A: Assumptions and Limitations A-1 Contents page rev101.doc A.1 A-1 A.2 Limitations Scope and Methodology A-1 A.3 Major Changes incorporated in Scope and Methodology after consultation A-2 A.4 Assumptions Route Wide A-3 A.5 Limitations Route Wide A-4 A.6 Assumptions - Western Route Section A-5 A.7 Assumptions Central Route Section A-7 A.8 Assumptions North-East Route Section A-9 A.8 Assumptions South East Route Section A-11 Appendix B: Mitigation Provisions B-1 B.1 Assessment and Planning B-1 B.2 Site Drainage B-1 B.3 Protection of Watercourses B-1 B.4 Control of Pollution of Surface Water B-2 B.5 Control of Pollution of Groundwater B-3 B.6 Mitigation of Impacts at Abstraction Boreholes B-3 B.7 Dewatering B-3 B.8 Monitoring and Mitigation of Water Levels in the Shallow Aquifer B-4 B.9 Dredging B-4 B.10 References B-4 Appendix C: Baseline Data C-1 Appendix D: Estimation of Groundwater Source Protection Zones D-1 D.1 Scope D-1 D.2 Methodology D-1 D.3 Calculated TTZs D-2 D.4 Appendix: Details of Calculations D-3 D.4.1 Method D-3 D.4.2 Parameters D-4 D.5 Results D-5 Appendix E: Analysis of Impacts on Groundwater E-1 E.1 Introduction E-1 E.2 Scope E-1 E.3 Impacts on Water Levels in the Deep Aquifer E-3 E.3.1 Introduction E-3 E.3.2 Methodology E-3 E.3.3 Results of Dewatering Assessment E-5 E.4 Deep Aquifer: Impact of Dewatering E-9 E.4.1 Simulated Dewatering Impacts E-9 xvi

21 E.4.2 Implications for Crossrail E-21 E.4.3 Impact of Dewatering on Water Quality E-22 E.5 Dewatering: Shallow Aquifer E-25 E.5.1 Introduction E-25 E.5.2 Estimated Flow Rates Required for De-watering E-25 E.5.3 Implications for Crossrail E-27 E.6 Shallow Aquifer: Impacts of New Structures E-27 E.6.1 Introduction E-27 E.6.2 Groundwater Modelling E-28 E.6.3 Results E-31 E.6.4 Main Findings E-34 E.6.5 Summary of the Predicted Impacts of Works in the Shallow Aquifer E-35 E.7 Figures E.3 to E.14 E-39 Appendix F: Impact Register F-1 Appendix G: Utility Works in Relation to Water Resources G-1 Appendix H: Flood Risk Assessment (see Appendix for more detailed contents list) Tables Table C.1: Groundwater Abstractions C-1 Table C.2: Surface Water Abstractions C-10 Table C.3: Surface Water Abstractions from the Thames (Teddington Lock to Maidenhead) C-13 Table C.4: Surface Water Discharges C-15 Table C.5: Surface Water Quality Scores C-23 Table C.6: Chemistry and Biology Classification C-25 Table C.7: Nutrient Classification and Aesthetics C-26 Table C.8: River Quality Target Classification C-27 Table C.9: Water Quality Data from the Thames C-28 Table C.10: Water Quality Data from West India Docks C-30 Table C.11: Borehole References as displayed in Figures C.6 and C.7 C-36 Table C.12: Water Quality of Groundwater in the Shallow Aquifer C-39 Table C.13: Water Quality of Groundwater in the Deep Aquifer C-41 Table C.14: Groundwater Levels from Recent Geotechnical Investigation C-42 Table D.1: Calculation of TTZs Central and East Route Sections D-7 Table D.2: Calculation of TTZs Western Route Sections D-11 Table E.1: Central Route Section E-5 Table E.2: South East and Western Route Sections E-7 Table E.3: Summary of Dewatering Requirements E-9 Table E.4: Calculation of Indicative Flow Rates E-12 Table E.5: Historic Dewatering Flow Rates E-13 Table E.6: Dewatering Simulation (Q in 1000 m3/d) E-14 Table E.7: December 2007 Water Balance E-16 Table E.8: Licensed and Planned Abstractions within the 2 m Drawdown Contour E-17 Contents page rev101.doc xvii

22 Table E.9: Additional Licensed and Planned Abstractions within the 0.5 m Drawdown Contour E-18 Table E.10: Simulated Water Level Change 1990 to 2008 E-20 Table E.11: Summary of Potential Impacts E-21 Table E.12: Potential Change in Chloride Concentration of the Thames as a Result of Discharge of Dewatered Effluent E-24 Table E.13: Drawdown Calculations, Scenario 1 E-26 Table E.14: Drawdown Calculations, Scenario 2 E-27 Table E.15: Hydraulic Parameters used in Model Runs E-30 Table E.16: Model Results E-33 Table E.17: Summary of Groundwater Level Impacts in Shallow Aquifer in Central Route Section E-36 Table E.18: Summary of Groundwater Level Impacts in Shallow Aquifer in South-East Route Sections E-38 Table F.1 Route Wide Impact and Generic Mitigation Register F-4 Table F.2 Impact Register Western Route Section F-5 Table F.3 Impact Register Central Route Sections F-6 Table F.4 Impact Register North East Route Sections F-7 Table F.5 Impact Register South East Route Sections F-8 Table G.1 Western Route Section G-1 Table G.2 Central Route Section G-2 Table G.3 North East Route Section G-3 Table G.4 South East Section G-4 Figures Figure C.1: Water Quality Data from the Thames at Greenwich Reach C-29 Figure C.2: Groundwater Quality Data from Canary Wharf (Chloride, Calcium Carbonate, Sulphate, Sodium and EC) C-32 Figure C.3: Groundwater Quality Data from Canary Wharf (Iron) C-33 Figure C.4: Extent of Saline Intrusion based on 177 mg/l (5 mmol/l) Isochlor C-34 Figure C.5: Extent of Saline Intrusion based on 150 mg/l Isochlor C-35 Figure C.6: Deep Aquifer Groundwater Chloride Concentrations C-37 Figure C.7: Durov Triplot C-38 Figure C.8: Indicative Solid Geology from LBGM and Borehole Data: Western Route Section (Route Windows W25 to W1) C-46 Figure C.9: Indicative Geology from Borehole Data: Central Route Section (Route Windows C1 to C13) C-47 Figure C.10: Indicative Geology from Borehole Data: Stepney Green to Victoria Dock Portal (Route Windows C9 to SE2) C-48 Figure C.11: Indicative Solid Geology from LBGM: North East Route Section (Route Windows NE1 to NE12) C-49 Figure E.1: Conceptual Methodology Deep Aquifer Dewatering E-4 Figure E.2: Simulated Dewatering Scenario E-15 Figures E.3 to E.14 are located in Section E.7 together with the Observed vs. Simulated Groundwater Levels: 1985 to 2015: xviii Contents page rev101.doc

23 Figure E.3: December 2007 Chalk Water Levels: Without Crossrail Dewatering Figure E.4: December 2007 Chalk water Levels: With Crossrail Dewatering Figure E.5: Crossrail Dewatering Locations Figure E.6: Predicted Drawdown: December 2007 Figure E.7: Groundwater Abstractions and Predicted Drawdown: December 2007 Figure E.8: Locations of Selected Observation Wells Figure E.9: Change in Water Balance Components due to Crossrail Dewatering Figure E.10: Difference in Flow Direction and Magnitude with and without Crossrail Dewatering: December 2007 Figure E.11: Increase in Flows from River Thames into Aquifer Figure E.12: Base Case Scenario - Interaction Between the Aquifer and the River Thames, December 2007 Figure E.13: With Dewatering - Interaction Between the Aquifer and the River Thames, December 2007 Figure E.14: Groundwater Abstractions and Predicted Drawdown: March 2008 Following Figure E.14: Observed vs Simulated Groundwater Levels: 1985 to 2015 (21 locations) Figure E.15: Model Set-up E-29 Figure E.16: Base Case Water Levels E-31 Figure E.17: Impacts on Water Levels from an 80m-wide Structure E-32 Figure E.18: Model Results (Plan View) E-32 Figure E.19: Impacts on Water Levels from a Structure E-34 Volume 3 Drawings Contents page rev101.doc xix

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25 1 Background and Introduction This volume contains the main text of the Assessment of Water Resource Impacts, Technical Report of the Crossrail Project. This main text should be read in conjunction with two connected volumes, which contain the appendices and drawings showing the surface and groundwater baseline and residual impacts. These two volumes are referred to in the main text as the Appendices (Volume 2) and the Drawings. Chapter 2 of this volume contains general information about the Crossrail project. Chapter 3 contains the scope and methodology for water impacts as developed from that presented in the Scoping and Methodology Report produced by ERM in Impacts and assessment that are generic to all four route sections are covered in Chapter 4 to avoid excessive repetition within the text on the individual route sections and route windows. The assessment of the impacts on the water environment of Crossrail Line 1 is broken down by the four route sections in Chapters 5 to 8. Each route section is presented in a separate chapter, which is organised as described below. The introduction to each route section contains information about general issues that apply to the whole section, e.g. tables with baseline information and generic impacts. This is followed by a description of each route window within the route section, which contains an outline description of works relevant to water resources, including assumptions where necessary (note: a full scheme description can be found in the Environmental Statement), a summary of baseline information and the impact assessment specific to that route window. A concluding table is presented for each route section summarising the significant residual impacts within the route section. Working papers relating to some subjects have been presented previously to the Environment Agency. The information held in these working papers is contained in the Appendices. A summary of the contents of the Appendices is listed below: Appendix A: Appendix B: Appendix C: Appendix D: Appendix E: and quality Appendix F: window Appendix G: assumptions and limitations applicable to this assessment mitigation provisions baseline data including groundwater quality, abstractions and discharges data and results of the estimation of Source Protection Zones (SPZs) examination of possible impacts caused by Crossrail works on water levels a summary of the impact assessment and mitigation measures for each route a summary of utility works in relation to water resources 1 Crossrail Line 1 is hereafter referred to as Crossrail Chap 1 to 3.doc 1-1

26 Appendix H: flood risk assessments A complete list of all published reports and documents utilised during the production of this technical report is contained in the Reference List, Section 12. Water related references are provided in the text of this report where appropriate. Chap 1 to 3.doc 1-2

27 2 Introduction to Crossrail (CLRL), a joint venture between Transport for London (TfL) and the Strategic Rail Authority (SRA), is currently developing proposals for Crossrail. Crossrail is a major new cross-london rail link project that has been developed to serve London and the southeast of England. Crossrail will support and maintain the status of London as a world city by providing a world class transport system. The project includes the construction of a twin-bore tunnel on an east-west alignment under central London and the upgrading of existing National Rail lines to the east and west of central London. The Crossrail route is shown in Figure 2.1. The project will enable the introduction of a range of new and improved rail journeys into and through London. It includes the construction of seven central area stations, providing interchange with London Underground, National Rail and London bus services, and the upgrading or renewal of existing stations outside central London. Crossrail will provide fast, efficient and convenient rail access to the West End and the City by linking existing routes from Shenfield and Abbey Wood in the east with Maidenhead and Heathrow in the west. Crossrail will be a significant addition to the transport infrastructure of London and the southeast of England. It will deliver improved services for rail users through the relief of crowding, faster journeys and the provision of a range of new direct journey opportunities. The project will also have wider social and economic benefits for London and the southeast of England. Powers are being sought by means of a hybrid Bill (referred to as the Bill ) promoted by the Secretary of State for Transport to construct the Crossrail project and operate the railway. In accordance with the provisions of the relevant parliamentary procedures, the Bill will be accompanied, on deposit, by the Environmental Statement. The Assessment of Water Impacts Technical Report is a source document for the Environmental Statement. Chap 1 to 3.doc 2-1

28 Figure 2.1: Overview of Crossrail Route Chap 1 to 3.doc 2-2

29 2.1 Objectives of Crossrail Crossrail s three key objectives are: to support the development of London as a world city, and its role as the financial centre of Europe and the UK; to support the economic growth of London and its regeneration areas by tackling congestion and the lack of capacity on the existing rail network; and to improve rail access into and within London. Crossrail will achieve these objectives by addressing problems of inadequate capacity on the National Rail and London Underground networks, by improving accessibility to regeneration areas, and by providing transport capacity for the growth expected for London. 2.2 Overview of Engineering Works Crossrail s route has four distinct sections: a central section within central London and, outside central London, western, northeastern and southeastern sections. In the west, Crossrail will use the Great Western Main Line (GWML) between Maidenhead and Westbourne Park. The existing 25 kv overhead electrification between Paddington and Airport Junction will be extended to Maidenhead and bridge alterations will be undertaken as necessary. The main infrastructure changes are the construction of a flyover structure (the Stockley flyover) to allow Crossrail trains to access the existing tunnelled spur to Heathrow and the provision of a rail underpass (a dive-under) west of Acton Yard. A new line, within the existing railway corridor, will be provided between Langley and West Drayton. Enhancements will also be made to stations, with the most significant works being at Ealing Broadway, Southall, Hayes and Harlington, West Drayton, Slough and Maidenhead. New stabling sidings are also proposed at Old Oak Common, West Drayton and west of Maidenhead station. The central route section will consist largely of a twin-bore tunnel beneath central London with portals at Royal Oak in the west, Pudding Mill Lane in the northeast and Victoria Dock Road in the southeast. The central route section extends from a point around 200m west of the A40 Westway to a point around 500m to the east of the portal at Pudding Mill Lane in the northeast and a point just to the east of Poplar Dock and the A1206 Prestons Road in the Isle of Dogs in the southeast. New stations and associated structures, such as ventilation shafts, will be provided along this part of the route. On the northeast route section, Crossrail will use the existing Great Eastern Main Line (GEML) between Pudding Mill Lane and Shenfield. The main infrastructure changes are a new train maintenance depot west of Romford station and the reinstatement of a track between Goodmayes and Chadwell Heath. Enhancements will also be made to stations, with the most significant works being proposed at Ilford and Romford. This route has existing 25kV overhead electrification. New stabling facilities will be provided at Gidea Park. Chap 1 to 3.doc 2-3

30 The southeast route section runs between a point to the east of the Isle of Dogs station and the eastern terminus at Abbey Wood, where Crossrail will serve a reconstructed station. Crossrail will operate in a twin-bore tunnel to Victoria Dock portal where it will serve a reconstructed station at Custom House. The route will then follow the existing alignment currently used by the North London Line through the Connaught Tunnel to Silvertown. At North Woolwich, a new twin-bore tunnel to Plumstead, referred to as the Thames Tunnel, will pass beneath the River Thames. Two new tracks will be provided between Plumstead and a point east of Abbey Wood station to accommodate Crossrail services on the North Kent Line corridor. This route will be provided with 25kV overhead electrification on the Crossrail lines. Chap 1 to 3.doc 2-4

31 3 Methodology for Water Resources Assessment 3.1 Introduction This section describes the scope and methodology for the assessment of impacts on surface and groundwater features covered in this report. A draft Scoping Report was circulated for comment in September The scope and methodology described below has been updated to address, as far as possible, issues raised by consultees. The changes from the original Scope and Methodology are listed in Appendix A. 3.2 Scoping Potential Impacts A scoping exercise was undertaken to identify potential impacts that would arise from the construction and operation of Crossrail. Potential impacts from the construction included the following: temporary changes to surface water morphology (including the realignment of watercourses and alterations to stream beds); changes to surface water flow regimes, including the potential for flooding; temporary physical interference with features/resources including direct damage to watercourses, abstraction well infrastructure and drains caused by construction activities; changes to surface water quality due to physical, chemical and biological contamination; changes to groundwater levels and flow regimes, including changes to aquifer recharge rates, increased groundwater mixing, dewatering activities, and the opening or closure of fissures due to vibration, settlement or other causes. Changes to groundwater flows and levels may also impact upon surface waters fed or controlled by groundwater; changes to groundwater quality due to physical, chemical and biological contamination, including the disturbance of foul sewerage and existing contaminated land; and changes associated with discharge of water from construction work (including from dewatering operations) to sewers. Permanent impacts associated with operation were addressed and included the following: Chap 1 to 3.doc 3-1

32 effects of changes to surface water quantity (resulting from the permanent realignment of watercourses and alterations to stream beds) including, increased flood potential, loss of floodplain storage and erosion capacity, modified sedimentation, altered land drainage, various impacts on aquatic conditions at designated habitats, and the variation in runoff characteristics from new track, stabling and buildings; changes to groundwater levels and flows, including alterations to groundwater recharge rates, modified flow regimes due to tunnel and shaft constructions and ongoing dewatering effects due to tunnel inflows/seepage. All of these may also have an effect on borehole yields. Changes to groundwater flows and levels may have a secondary impact on surface waters fed or controlled by groundwater; and changes to surface and groundwater quality due to physical, chemical and biological contamination which may result from both accidental and routine occurrences, such as those relating to maintenance activities. These temporary and permanent impacts have been investigated through the methodology outlined below Definition of Scope (i) Spatial Scope: Surface Water The study area was defined by the surface and groundwater catchment through which the route passes. The assessment considered impacts on surface waters within a minimum 500m corridor either side of the route alignment. A m assessment radius was used for stations associated with major restructuring or dewatering works. The larger station area reflects the more extensive nature of the station works. Impacts were assessed downstream as far as the Teddington Lock or the confluence with the River Thames if further downstream (if there were sensitive receptors affected) The Thames below Teddington Lock was assessed where relevant for the project (eg Limehouse reach to Gallions Reach). The surface water study area also took into account: all surface water abstractions falling within the surface water catchments crossed by the route from 500 m upstream to the tidal outfall downstream; all consented discharges falling within the surface water catchments crossed by the route from 500 m upstream to 500 m downstream; all existing water quality records within the surface water catchments crossed by the route from 500 m upstream to the tidal outfall downstream; for flooding and floodplains, all reaches to the upstream and downstream hydraulic control structures; for flooding and floodplains, all land on the functional floodplain (i.e. land not defended to the 1:100+20% flood event); and Chap 1 to 3.doc 3-2

33 changes associated with discharge of water from construction work (including from dewatering operations) to sewers. (ii) Spatial Scope: Groundwater The groundwater assessment included a 500 m corridor either side of the route alignment and all groundwater abstraction catchments (represented by the outer source protection zone (SPZ)) a part of which falls within this corridor. A m assessment radius was used for stations where major restructuring or dewatering works are proposed. In the absence of documented source protection zones, the groundwater study area was derived from conservative catchment estimates, based on known geology, piezometry and abstraction conditions. Where the deepest level of any construction works falls within the London Clay, the Chalk aquifer was considered to be hydraulically independent and at no risk from potential pollution. Although this is generally the case, the presence of so called scour hollows, sand layers and geological faults was also taken into account when assessing the risk of impacts on groundwater quality. (iii) Temporal Scope The assessment addressed both construction and operation. Construction will take place from 2007 to 2013, however the duration of works at specific sites will vary. Assessment of route operation assumes it will commence in 2013 and takes account of the design life of the proposals. The baseline condition was taken as that observed during 2003/2004. However, it was acknowledged that some changes in the baseline, particularly in relation to groundwater levels, may occur before the commencement of construction works in Where these could be reliably estimated they were incorporated into the baseline assessment. The legislative framework was taken to be that current in England in 2003/2004 although anticipated changes may also be taken into account. For example, changes to abstraction licensing, with implications for dewatering, will be made through the Water Act 2003 although the timetable for implementing the various schedules has not been clarified. Further changes in water quality standards and catchment management practices may also result from implementation of the Water Framework Directive Inventory of Resources and Receptors The resources and receptors comprised all controlled waters, including: groundwater resources and receptors (both major and minor aquifers) including: licensed and protected rights to abstract groundwater (including rights under application through Section 32 consents or in determination) for purposes including public water supply, private and industrial water supply and agricultural water supply; and Chap 1 to 3.doc 3-3