A tunnel the length of three football pitches has been dug under Hammersmith to help tackle sewage pollution in the River Thames.

The 300m-long connection tunnel between Hammersmith Pumping Station and the middle of the River Thames will eventually connect into the 25km Thames Tideway Tunnel, under construction to tackle sewage overflows from London’s Victorian sewers.

Hammersmith Pumping Station currently spills around a million tonnes of untreated sewage into the Thames each year on average, making it one of the most polluting overflow points along the River Thames.

The tunnel is 5.1m in diameter for the first 50m, then narrows down to 4m diameter. It is the first fully excavated tunnel as part of the ‘super sewer’ project and will come into operation once work is complete in 2025*.

Morgan Anamoah, Project Manager at Tideway, said: “Although it’s not the biggest on the project, this is the first fully excavated tunnel for the super sewer, a huge step in our work towards cleaning up the River Thames. Our work in Hammersmith will help stop one of the most polluting sites along the river and it is something we’re all immensely proud of.”

Excavation of the tunnel started in August 2018 using mechanical excavation, one metre at a time, before a sprayed concrete lining (SCL) was applied to the exposed clay using a robotic manipulator.

The sprayed concrete lining at Hammersmith is also the first time a waterproof sprayed concrete has been used in the UK. This reduced the time spent on the job, as no waterproof membrane is required between the primary and secondary linings.

Ed Batty, a Tunnel Agent at Hammersmith, said: “The levels of production and quality have been exceptional, and that’s really down to the engineers and the miners who have shown real passion toward getting the job done.” 

Notes to editors

Tideway
Tideway is the independent construction company delivering London’s super sewer, the Thames Tideway Tunnel, which is a 25km sewer tunnel urgently required to tackle sewage pollution in the tidal River Thames. One in every 50 site jobs is an apprenticeship. Construction from 24 sites across London is due for completion by 2025*. For more information visit www.tideway.london

*This article has been amended to reflect the project's updated completion date following an analysis of the impacts of the pandemic.