Barhale chosen for £36m London sewer project

The Northern Outfall Sewer passes above the Jubilee Line, Docklands Light Railway and Manor Road

Thames Water has appointed Barhale to deliver a £36m remediation project on an essential gravity sewer in East London. 

The innovative relining work will be carried out on the Northern Outfall Sewer (NOS)  as it passes above the Jubilee Line, Docklands Light Railway and Manor Road in West Ham.

The NOS is a 7.5 km-long wastewater asset running across East London that transfers flows from a 300sq km catchment to Beckton Sewage Treatment Works.

The sewer is made up of five separate parallel sewer barrels.

Three were originally constructed by Sir Joseph Bazalgette between 1860 and 1865 with another two added around 60 years later. Each existing sewer barrel is 2.7metres in diameter. 

Works are constrained by the need to maintain flows through the sewer throughout the programme and to minimise disruption to train travel. 

Wastewater passes through the pipes at a combined rate of more than 22,000 litres per second – meaning that over pumping is not feasible. Instead, a series of carefully phased isolations will make the works possible. 

No more than two sewers will be taken out of service at any one time, keeping at least three live at all times. 

Once isolated, civil engineering and infrastructure specialist Barhale will strengthen the existing structure with a specially-designed Duplex Stainless Steel pipes.

Barhale’s senior contracts manager Jaimie Lawson explained that the company is working closely with Thames Water to develop a phased approach.

“We are shaping the programme to allow sewer flows to continue throughout the works while avoiding rail possessions and disruptions to road traffic,” he said. 

“Although the NOS is an essential part of London’s water infrastructure, it is probably less well known that it also forms the bed for the popular Greenway footpath and we want to make sure that we minimise any impacts on the community.”  

Barhale is working with Thames Water to conduct the design and build project. 

The project will increase the design life of the asset for another 120 years. Completion is expected in summer 2027.


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