Tideway | Tunnel lining milestone reached on London ‘Super Sewer’

The secondary lining on the 7km western section of London’s super sewer has been completed, marking a significant milestone for the Tideway project.

The secondary lining works in the western section started in March 2021 and have required more than 800 individual concrete pours to make the journey from Acton to Fulham in south-west London.

The concrete was batched on site at the Carnwath Road Riverside site in Fulham and delivered to the six shutters by concrete trains known as bullets to a pump located on a logistics crossing within the tunnel.

Around 48,000m3 of concrete was used to create the secondary lining in this section of tunnel.

Tideway project director Sally Cox said: “This is fantastic achievement for everyone involved.  I am in awe of the endless spirit and perseverance from the team to overcome challenges to deliver this phase of work. It is amazing what you can achieve when you have such a brilliant team.”

Secondary lining is required to provide additional strength to the super sewer and to create a smooth surface over which flows will travel once the sewer is operational in 2025.

The main drive of the 6.9m internal diameter, 7km tunnel was completed by tunnel boring machine Rachel in late 2020 and the team are now preparing the site to undertake the secondary lining of the main shaft at Carnwath Road Riverside.

The western section is overseen by BMB, a joint venture between Bam Nuttall, Morgan Sindall and Balfour Beatty.

The contractors on the east section of the Tideway project is a joint venture between Costain, Vinci Construction Grands Projets and Bachy Soletanche.

In the central section, it is FLO, a joint venture between Ferrovial and Laing O’Rourke, that is carrying out the work.

Primary lining was completed for the entire sewer in April.

The new sewer is designed to capture more than 95% of the sewage spills that enter the river from London’s Victorian sewer system. It will have a significant impact on the water quality, making it a much healthier environment for wildlife to survive and flourish.

Earlier this year, Tideway reported a further £100M cost increase on its London Super Sewer project.

Tideway’s overall cost estimate has increased to £4.3bn from its original budget of £3.52bn, announced in 2014. That is £190M more than was reported in 2021’s annual report and is up on the £4.2bn cost estimate announced in Tideway’s interim report, published in November last year.

The cost hike comes despite good progress on the scheme with 77% of construction work complete at year end, including the completion of main tunnelling work.

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