The Thames Tideway Tunnel will provide a solution to London’s pressing sewerage capacity problems when it’s completed in around 2023. The 15 mile long tunnel, which will mainly follow the line of the River Thames at a depth of some 200 feet in places, will run from Acton in west London to Stratford in the east where it will connect with the newly constructed Lee tunnel which will transfer the sewage to treatment works at Beckton.
At an estimated cost of £4.2 billion – nearly half that of the 2012 London Olympcs – it will be the UK water industry’s largest ever infrastructure project.
The big drainage problem – The backbone of London’s sewers is the ingenious system constructed in the 1860s by Sir Joseph Bazalgette. It’s still in excellent working order, but current and likely future demands mean it simply cannot cope. The result is that the River Thames is now becoming what it was some 150 years ago – an open sewer as the overflow is pumped straight into the river. According to the Thames Tideway Tunnel Ltd website, some 55 million tons of sewage entered the Thames in 2013, or 8 billion toilet flushes.
Bazelgette’s sewers catered for a London population of 2 million, and even though he had the foresight to provide capacity for 4 million this has been dwarfed by a current population of well over 8 million – a figure that will rise in the future.
How will the Tideway Tunnel stop sewage entering the Thames?
Bazalgette’s sewers incorporate overflows where, in periods of high demand such as heavy rainfall, sewage drains into the river. When they were originally constructed, these overflows might only discharge into the Thames once or twice a year during heavier rain storms. Nowadays, it usually occurs every week and as little as two millimetres of rain can cause an overflow.
The Tideway Tunnel will intercept the overflow before it can enter the river through a large down pipe connected to the existing overflow pipe. From here, the sewerage is transferred to the 7.2 metre diameter tunnel where it is carried eventually to Beckton treatment works.
Other benefits for London
Along with the major benefit of the Thames no longer carrying raw sewage, the Tideway Tunnel provides other advantages for the capital
1. Helps upgrade London’s sewer and drainage system to cope with an increasing population and the likely requirement for some 600,000 new homes.
2. Enhances and protects London’s environment with a cleaner river and protects the health of river users.
3. Improves the economy – could help revive the capital’s river trade.
4. Jobs and prosperity. At its peak, there will be some 6,000 people employed in the Tideway Tunnel project.
5. Ecological: the Thames has been cleaned up considerably over the past 30 years, the drastic reduction in sewage will end the last main cause of river pollution.
London’s drainage and sewerage upgrade
Thames Water’s website outlines other upgrades to the capital’s sewerage facilities already completed and underwayAlong with the Tideway Tunnel construction, the Lee Tunnel – running for four miles from Stratford to Beckton – has been constructed at a cost of £635 million, and all five of London’s major sewage treatment facilities have been upgraded in a £675 million project including a £190 million investment in the Beckton facility, the largest single sewage treatment works in Europe and the one that will handle the Tideway Tunnel’s sewage. The upgrade sees its sewage handling capacity rise by 60%.
A long term sewerage and drainage answer
Sir Joseph Bazalgette’s sewers have long needed an upgrade to cope with the capital’s rising drainage and sewerage demands, and in the Tideway Tunnel and related upgrades they’re finally getting it. It’s said that the improvements will meet London’s needs well into the 22nd century, and will bring various boosts to the capital covering environmental, ecological and economic factors.
Post by Fraser Ruthven, the Growth and Strategy Manager for the Capitals leading drainage companies – London Drainage Facilities. Fraser and the team fully support the project and believe it will improve London on a vast scale.