Tideway has activated the new super sewer in London, UK, designed to stop sewage from entering the River Thames.
After 10 years of construction, the final of 21 connections was made between the Victorian sewers and the 25km Thames Tideway Tunnel.
This brings the system online, preventing sewage pollution in the tidal Thames.
Tideway, owned by a consortium of investors, is delivering the Thames Tideway Tunnel.
Preparatory work started in 2015, and construction is now ongoing at 24 sites across London. The project is set to be completed in 2025.
The tunnel will cost £4.5bn, funded by Thames Water’s 15 million customers.
Tideway CEO Andy Mitchell said: “This is another significant step forward, with this final connection complete, the super sewer is fully up and running and protecting the Thames.
“Our next step is to test it in storm conditions, which is why we are keeping a close eye on the weather, and we will do this over the coming months.”
The 25km-long super sewer connects to the existing 6.9km Lee Tunnel, a Thames Water asset, forming the London Tideway Tunnel (LTT) system. The full system went online in autumn 2024.
Construction began in 2016, with work taking place across two dozen sites from Acton in west London to Abbey Mills Pumping Station in east London.
Over 20 deep shafts were built across London to divert sewage flows and lower tunnelling machines underground.
The first giant tunnelling machine began work in 2018. Primary tunnelling on the 25km main tunnel and two smaller connection tunnels was completed by 2022.
By autumn 2023, secondary tunnel linings were finished across all tunnels, with the heavy civil engineering work wrapped up by spring 2024.
The Tideway project is being delivered by a consortium of contractors. The west region is handled by a joint venture of BAM Nuttall, Morgan Sindall Infrastructure, and Balfour Beatty.
The central region is managed by Ferrovial Agroman UK and Laing O’Rourke. The east region is delivered by Costain, Vinci Construction Grands Projets, and Bachy Soletanche.
Amey is responsible for system integration, providing process control, communication equipment, and software for operation, maintenance, and reporting.
The project is on track for full completion, including testing, later this year.
Mayor of London, Sadiq Khan said: “We must now build on this work to go further and tackle the other sources of pollution damaging London’s waterways.”
