New data recently published shows the impact of London’s new super sewer on the River Thames.
The new tunnel network, which combines the 25km Thames Tideway Tunnel and Thames Water’s existing 7km Lee Tunnel, captured nearly 850,000 tonnes of sewage in a single 24h period.
The new super sewer is designed to ‘intercept’ spill points in the river wall and improve the health of the River Thames.
In October, the company announced that the first of the 21 connection points had been activated. Since then, more have come online – bringing the total to 12.
These include key interception points in Chelsea, Blackfriars and Westminster. Historically, London’s existing sewer network was overwhelmed during even light rainfall, with storm flows discharged directly into the Thames.
Roger Bailey, Tideway’s Chief Technical Officer, said:
“These new figures show the super sewer starting to do its job. As more connections come online, the protection of the river will increase further, dramatically improving its health. There is still work to do but our teams are working hard to make the new infrastructure fully operational next year.”
Nevil Muncaster, Asset Management and Engineering Director, Thames Water, added:
“During storms like we’ve just seen, the super sewer really come into its own; successfully protecting the environment from wastewater overflows that would otherwise have been necessary.
“The Thames Tideway Tunnel is a significant part of our overall investment programme, developed over many years, to improve the health of the Thames. Collectively these investments will culminate in a 95% reduction in storm overflows in the capital once it’s fully commissioned next year.
“This huge infrastructure project is on track for completion next year and is being delivered within the original cost estimate to billpayers. The River Thames, and Thames Water customers, will continue to reap the benefit for many decades to come.”
Work on the project began in 2016 – with activity taking place at two dozen construction sites from Acton in west London to Abbey Mills Pumping Station in Stratford, east London.
More than 20 deep shafts – some as wide as the dome of St Paul’s Cathedral – were constructed across London to divert sewage flows and to lower tunnelling machines into the ground.
The first of these giant machines started work deep beneath London in 2018, with primary tunnelling on the 25km main tunnel and two smaller connection tunnels fully completed in 2022.
By the autumn of 2023, secondary lining was fully complete on all the tunnels, with the heavy civil engineering work then completed in the spring of 2024.
The project is due to be fully up and running (with testing complete) in 2025. Thames Water will then operate the system, as part of its London wastewater network.
Recently published data shows that during heavy rainfall in London on Wednesday (November 27th), 848,365m3 was captured by the tunnel system.
At its peak, the entire system was over half full, containing nearly one million tonnes of storm sewage.
