The London Tideway Tunnels Creating a cleaner, healthier River Thames Si a n Thomas, Thames Tunnel Project Manager

1. The London Tideway TunnelsCreating a cleaner, healthier River ThamesSian Thomas, Thames Tunnel Project Manager 14 October 2008

2. Improving the Tidal River Thames • Latest contribution to river water quality improvements • Building on the legacy of Sir Joseph Bazalgette’s intercepting sewers • Many years of investment in Sewage Treatment Works (STWs) in the Thames catchment area • Main drivers • River quality (fish, health & litter) • UK compliance with legislation • Reputation of London as a world class city • Two separate tunnels – the Thames Tunnel and Lee Tunnel – reducing discharges from CSOs • Investment to improve the STWs discharging into the tidal River Thames

3. The Old Rivers of London Hackney Brook Stoke Newington River Lee River Roding Hampstead Kilburn Fleet Islington Bow Barking Creek Tyburn Walbrook Black Ditch Westbourne Hounds Ditch Oldbourne Notting Hill Erith Stamford Brook Neckinger Kings Scholar’s Pond Waterloo Counters Creek Earl Chelsea Woolwich Deptford Creek Battersea KidBrook Peck Effra Eltham Falcon Brook Wandle Roehampton Forest Hill Ravensbourne Beverly Brook Quaggy Streatham Graveney Beverley Brook 8383

4. Intercepting Sewers by the Metropolitan Board of Works 1859 - 1873

5. Storm Relief Sewers & Pumping Stations 1910 to 1960

6. London’s Sewerage System

7. Combined Sewer Overflows (CSOs) • Bazalgette’s sewerage system designed with 57 Combined Sewer Overflow (CSO) points along the tidal River Thames – public health driver • CSOs prevent flooding to buildings and streets by spilling excess sewage into the river during heavy or prolonged rainfall • 32 million tonnes (average) of diluted storm sewage discharged annually • Up to 60 discharges a year on average – more than once a week.

8. 21st Century Challenges • Increasing urbanisation – paving over of gardens; loss of land available to soak up rainfall • Climate change leading to more frequent, more intense storm events. August 2004: average monthly rainfall within a couple of hours (west London). • Population growth – more than a million additional people in London by 2029

9. CSO Impacts • Reduced levels of oxygen affect aquatic wildlife e.g. Aug 2004 event - 10,000 fish and 100,000 fish fry killed • Visible littering of the river shoreline from sewage-derived litter • Potential health risks to river users

10. Milestone Dates • February 2000Thames Tideway Strategic Study (TTSS) set up to investigate and propose solutions to CSO discharges • February 2005TTSS concluded need for both improvements to the existing STWs and building a tunnel to intercept 36 of the most polluting Tideway CSOs • August 2005Ofwat commissioned independent review by Jacobs Babtie • July 2006Government instructed Thames Water to evaluate two options for a tunnel under the tidal Thames

11. Milestone Dates • December 2006Submitted our report to Government on the assessment of the two options detailing costs and benefits • March 2007Minister Ian Pearson announced Government’s decision to support the development and implementation of the full-length tunnel solution • March 2008Appointed CH2M HILL as Programme Management capability to assist with delivery of the Tideway Tunnel

12. Thames TidewayAn Integrated Solution • London Tideway Tunnels and improvements to London’s five main STWs • Beckton, Crossness, Mogden, Longreach and Riverside improvements – funding agreed with Ofwat as part of Price Review process. • Beckton STW improvements needed to increase flow to treatment and treat storm sewage pumped out from the London Tideway Tunnels.

13. London Tideway TunnelsProposed Concept • Lee Tunnel (Abbey Mills to Beckton STW)6.9km long, >7m diameter, up to 75m deepIf approved approx 5 years to construct • Beckton STW ExtensionsIf approved approx 5 years to construct • Thames Tunnel (West London to Beckton STW)32.2km long, >7m diameter, up to 75m deep If approved approx 8 years to construct

14. Thames TunnelOverview • 32.2km tunnel from west London to Beckton STW in east London • Several major shaft sites along the tunnel route • 34 CSOs will connect into the tunnel • If approved, tunnel construction could start in 2012, lasting approximately 8 years

15. Thames TunnelTunnelling and CSO Connection Sites • Sites required for three main purposes: • Main construction shafts (X 3 – 5 approx) • Intermediate construction shafts (X 3 – 4 approx) • CSO connections (X 34) • Initial briefings held with 13 London Boroughs (Autumn 2008) • Site selection methodology under development for consultation • Securing sites is key to ongoing design development • Key constraints and challenges • Tunnelling at depth in varying ground conditions • CSO connections, surface works and connection to main tunnel • - Stakeholder engagement is vital

16. Blackfriars Bridge CSOEngineering Challenges

17. Thames Tideway Tunnel TimelineLee Tunnel, Beckton STW and Thames Tunnel Start Site InvestigationThamesTunnel2008 CommissionThamesTunnelJune 2020 ThamesReporttoGovernment Dec 2006 PlanningApplicationThamesTunnel2011 ThamesTunnelContract Awards2012 Minister’sDecisionMar 2007 Lee TunnelOJEU NoticeDec 2007 LeeTunnelContractAwardMar 2009 CommissionLee Tunneland Beckton STWJune 2014 Planning ApplicationLee TunnelandBeckton STWMay 2008