The Tideway Scheme: Taking a look at the Uk's largest infrastructure projects and where they are now

Posted on 02 August 2022

Over the next few weeks, we’ll be looking into the UK’s largest infrastructure projects and seeing where they’re at currently. We’ll be taking a deep dive look into Crossrail, Tideway, Hinkley Point C, Battersea Power station redevelopment, Stonehenge Tunnel, HS2, Leeds Flood Alleviation Scheme and Birmingham’s Big City Plan. The second project we’ll be looking at is the Tideway Scheme, a 25KM super sewer built under the Thames to intercept the overflow of sewage.

What is the Tideway Scheme?

The Tideway scheme is a 25km long tunnel that runs 70-metres below ground at its deepest, making it the largest water infrastructure project ever undertaken in the UK. The currently constructed tunnel runs from east to west London, transforming the 150-year-old sewer system.

Starting in 2016, the tunnel was aimed to be built by 2024 but due to the Covid-19 pandemic, it has been delayed to 2025.

The Tideway tunnel will capture storm sewage flows from 34 sewer overflow points situated along the river Thames, it will transfer the sewers' polluted water to Stratford to East Ham Lee Tunnels to deliver forwards to the Beckton Sewage Treatment Works, following treatment the clean water will be released into the Saline Thames Estuary.

The Tunnel will seize, at least, 94% of the millions of tonnes of sewage that overrides the sewers within London, as when the original London sewerage system was designed to serve 4 million people, now just over 9 million live in the capital.

What Contractors are involved in the project?

  • Licensed infrastructure provider Bazalgette Tunnel Ltd, which trades under the name Tideway

  • In charge of the Tideway West section are Balfour Beatty Group, Bam Nuttall and Morgan Sindall

  • The central section is being undertaken by Ferrovial Agroman UK and Laing O’Rourke Construction.

  • Managing the East section of the project are Costain, Vinci Construction Grands Projects and Bachy Soletanche

  • Responsible for providing Software systems, communications, process control, reporting and maintenance for the Tideway scheme is Amey.

  • Programme manager is Jacobs.


History of the Tideway Scheme

2014 - planning decisions and approval

2015 - Main works and financing contracts awarded

2016 - Primary work completed, and main works preliminary construction begins

2018 - the start of tunnelling

2019 - Secondary lining begins

2022 - end of the tunnelling     

Where is the Tideway Scheme currently?

Currently, at the Acton Storm Tanks, the first six metres of the shaft secondary lining have been poured, at Carnwath Road riverside the tunnel is 86% complete between Fulham and Battersea. Aggregate Material has been used to fill the temporary sheet-piled cofferdam at Putney Embankment Foreshore which is forming part of the larger site being excavated and transported by barge.

At Chelsea Embankment Foreshore the removal of a section of Cofferdam begins ahead of diverting the old sewer through the new structure, the secondary lining kit is being removed and transported to Chambers Wharf for reuse on the eastern section of the project

What's next?

The next phase of the Tideway Scheme is prepared to begin the secondary lining of the Greenwich connection tunnel.

The Tunnel is targeted for completion in the first half of 2025.

Click here to track the Tunnels progress which is updated once a week: Tideway Tracker

The Numbers

  • 39M tonnes of untreated sewage are currently discharged into the river Thames each year

  • There will be a 95% reduction in sewage pollution when the Tideway tunnel is in operation

  • The tunnel runs 25km long, spanning from East to West London

  • It provides a sewerage system that is fit for the next 100 years at least.

  • The tunnel currently has a cost of £4.2 billion.         

The first infrastructure project we looked at was Crossrail. Click here to read more.

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