Thames Water

Huge upgrade will intercept around 18 million tonnes of untreated wastewater now discharged annually into the river through numerous Victorian-era combined sewer overflows.

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Thames Water

Sewer program, covering 25 km, will continue through about 2023.

London utility Thames Water plc has named three U.K. construction teams for up to $3.5 billion of large-diameter tunnel work on its planned mega-sewer project, the 25-km Thames Tideway. Tunneling and separate financing contracts will be awarded this summer, with construction set to start next year.

The tunnel, with work projected to continue through 2023, will be the UK’s largest water-infrastructure project and is expected to create about 4,000 jobs, according to UK Building, a local publication.

With a total value exceeding $6.5 billion, the storage-transfer Tideway project will intercept around 18 million tonnes of untreated wastewater now discharged annually into the river through numerous Victorian-era combined sewer overflows, according to Thames Water. CH2M Hill Inc. is program manager.

The Tideway tunnel will run from Acton, in the west, to Abbey Mills pumping station in the east. It will then flow along the Lee Tunnel, now under construction, to the Beckton sewage treatment plant. With diameters from 6.5 m to 7.2 m, the tunnel will run largely along the Thames, up to 66 m below its bed.

Thames Tideway Tunnel Ltd. (TTT), the project company of the parent utility, has named as contractor for the project’s west tunnel section a joint venture of BAM Nuttall Ltd., Morgan Sindall Plc. and Balfour Beatty Group Ltd.

Winner of the central section is a joint venture of Ferrovial Agroman U.K. Ltd. and Laing O'Rourke Construction Ltd.

The eastern tunnel will driven by a team of Costain Group plc., Vinci Construction Grands Projets S.A., and Bachy Soletanche Ltd.

These lump-sum target design-build contractors will be assigned to the successful consortium of financiers, known as the Infrastructure Provider, that now is bidding to buy control of TTT. The consortium, which will be appointed this summer, will also acquire a contract to build, own, finance and maintain the project.

The Infrastructure Provider will raise roughly two-thirds of the required financing though equity and commercial debt, and Thames Water will find the balance.

To ease the raising of private finance, the government says it will underwrite some construction risks. Thames Water’s customers will ultimately fund the project though increased utility bills.