Work to deliver a multi-million-pound rehabilitation programme of Thames Water’s Northern Outfall Sewer (NOS) in East London took a major step forward over Easter after a second major rail possession allowed Barhale engineers to carry out structural works and take critical material samples.

The 7.5 kilometre NOS runs overground on an embankment across East London, transferring flows from a 300 square kilometre catchment to Beckton Sewage Treatment Works.

At the Corporation Street project in West Ham, the NOS09 overbridges cross the District Line and c2c line. Through the 100-hour joint Transport for London and Network Rail Easter possession, civil engineering, infrastructure and tunnelling specialist, Barhale removed redundant concrete structures from the bridge spans, cut 20 samples from the existing cast iron sewer barrels for testing and undertook coring investigations at the bridge abutments and piers and additionally updated 3D scan surveys.

The Easter possession provided an opportunity to access all three rail spans at the same time, allowing the samples and information needed to complete the design to be collected.

Jaimie Lawson, Senior Contracts Manager at Barhale, said:

“The possession has made it possible for the project to take another important step forward. The intelligence that we have gathered will be critical to the design of the NOS09 solution, extending its lifespan to 120 years.”

A previous 27-hour possession of the Jubilee and DLR at the NOS07 overbridge across Christmas 2025 saw the installation of two bespoke deck systems to protect the railway lines and provide a safe working platform for future works to proceed.

Each deck comprises aluminium trusses, structural ties and a steel durbar floor separating the operational railway from the Thames Water sewer system to improve long-term safety and resilience.

To meet the railway separation requirements, the flooring was designed to overlap and incorporate adjustable sections where the deck interfaces with existing abutment walls.

Jaimie Lawson continued:

“We are dealing with a critical Thames Water asset where it crosses five major transport routes including the Jubilee Line, DLR, Manor Road, the District Line and c2c.

“The successful completion of the latest possession shows how we and Thames Water safely execute complex engineering works around operational rail environments.”

Richard Smith, Head of Programme Delivery – Critical Assets, Capital Delivery London Infrastructure at Thames Water commented:

“I would like to thank Barhale, their supply chain partners and our colleagues in Network Rail and Transport for London, who have worked together to deliver these complex works over the last few months as part of our commitment to deliver the biggest asset upgrade in 150 years this investment period.”