Tideway East

The Tideway Scheme consists of designing and building a system for wastewater and stormwater transfer and storage in central London. No less than 32 kilometres of tunnels will be necessary to increase the capacity of the existing network. This ambitious project aims to intercept wastewater and stormwater and divert them into treatment plants to prevent effluents into the River Thames. VINCI Construction Grands Projets, in a joint venture with Costain Limited, and Bachy Soletanche Ltd have been invited to participate in the construction of the East works package, one of the three making up the Tideway project. This package will connect Chambers Wharf and the Abbey Mills Pumping Station where the Lee Tunnel starts in East London. It consists of the design and construction of two tunnel sections: a main 5.5-km tunnel and a connecting 4.6-km tunnel.

BACKGROUND

The idea of evacuating wastewater is not new. Sir Joseph Bazalgette, a British civil engineer during the Victorian era, already aspired to this. He is famous for his revolutionary project for an underground sewerage system (the Thames was an open sewer until then) to reduce the risk of cholera and eliminate foul smells. The Great Stink of 1858 accelerated the acceptance of the project. Sewer construction to evacuate wastewater started taking form and brought with it a revolution in sanitation. But given the high growth of the London population since the 19th century, this infrastructure proved to be insufficient. That is why, after the success of the Lee Tunnel, which helped prove our know-how in technical construction, we were invited to construct the East works package. This project will reconcile Londoners with the River Thames.

TECHNICAL OVERVIEW

The similarities between the Lee Tunnel and the East works package provide us with a definite advantage. The technique of five diaphragm wall shafts with a very low gap, successfully mastered by Bachy Soletanche, tipped the scales in our favour. Also, situated at a depth between 45 and 65 metres, the two tunnels are in the same type of soil (limestone) that we found along the route of the Lee Tunnel. This, along with the same diameter of the tunnel, means we can anticipate the use of the same type of earth pressure TBM.
However, unlike the Lee Tunnel, the Tideway project is in the heart of London. Nuisance management and relations with neighbours and local communities are crucial. Beyond the technical design of this construction, the public and existing infrastructure must be taken into consideration. As with the Crossrail C510 project involving the Liverpool Street and Whitechapel station tunnels, we plan to cover the first two shafts with soundproof structures. Controlling vibrations was optimised using a pile-driving technique assisted by a real-time monitoring system.
Finally, out of environmental concern, 100% of the backfill (including mucking) and stocks (tunnel segments, etc.) are evacuated by river. This decreases the number of lorries, but the whole river network has to be reconsidered to increase river transport in the medium term. A 5-day training to sail a barge, for instance, has been started.
This is a long-term project. VINCI Construction Grands Projets was convincing in its ability to support and train staff. The client was very pleased with the (A)live on Site and Skill Up programs on the Crossrail and Lee Tunnel projects.

This project marks our third commercial success on large-scale works in London. Also, our cooperation with Bachy Soletanche, which has already proven itself many times, is growing stronger. We are also proud of our rapport with the designer Mott MacDonald, the consortium’s designer on the Lee Tunnel project who is integrated into our team.

IMPACT

Finally, the Tideway Scheme aims to provide better management of wastewater and stormwater and thereby enhance London’s environment.
The city has built itself and its history around the River Thames, now reduced to a sewer. That is why this is not just an engineering project, but also a reconciliation of London with its river by cleaning up the Thames and making it an integral part of the city. This project contributes to the improvement of London’s environment and economy.
It will allow the English capital to have a sewerage system of the highest standards. Also, this project is going to create more than 4,000 direct jobs and an additional 5,000 or so indirect jobs. It will open up hundreds of opportunities to apprentice or return to work given our commitment to recruit local staff and will create a dynamic new river economy through jobs in the river and maritime sector.

Project participants

Client
Bazalgette Tunnel Limited

Project management
CH2MHILL

Key figures

Implementation dates
September 2015 to October 2022

Excavations

Main tunnel
340,000 m³

Connecting tunnel
145,000 m³

Shafts and connecting structures
130,000 m³

Testimonial

“The successful bidders for the three packages were selected because we had total faith in their ability to carry out the work safely by respecting the stakeholders and the environment.”

Andy Mitchell, THAMES TIDEWAY TUNNEL MANAGING DIRECTOR

More information