Construction completes on London’s super sewer

“This is the moment we’ve all been waiting for,” said Tideway chief executive Andy Mitchell. “The underground civil engineering on the Tideway project is now complete following eight years of dedicated hard work from all our teams working in the capital. “

The final element, completed just before Easter, was lifting a 24-metre-wide circular concrete lid over the shaft at Abbey Mills Pumping Station in Stratford. 

Using a purpose-built gantry crane and other manoeuvring equipment supplied and operated by Belgian specialist Sarens , it took five hours to put the 1,200-tonne lid into place. It was the heaviest lift of the whole project, surpassing the lowering of the six tunnel boring machines at the outset. 

The Thames Tideway Tunnel, also known as the London super sewer, is a 25km-long sewage tunnel designed to reduce pollution in the River Thames. In a typical year, tens of millions of tonnes of storm sewage spill into the River Thames. Just this weekend, Varsity Boat Race competitors were vomiting before the race and warned to stay out of the water. Once fully operational, the new sewer should almost completely eliminate those spills. 

As well as the 25km-long, 7.2m-wide main tunnel, a 4.5km connection tunnel in southeast London, and a 1.1km tunnel in southwest London have also been built. 

“There is still work to do,” Andy Mitchell said. “We need to finish some above-ground structures and, crucially, test the system – but this nonetheless marks an absolutely critical milestone for the Tideway project and for London.”

The shaft at Abbey Mills is the deepest on the project at 70 metres – and is the point at which the super sewer connects to the Lee Tunnel, which was completed in 2016.  This eastern section of the Tideway project is being delivered by a joint venture of Costain, Vinci Construction Grands Projets and Bachy Soletanche.

Robert Ricketts, Tideway’s project manager at Abbey Mills Pumping Station said of the final lift: “This manoeuvre was a complex operation, and required careful collaboration between various teams working on this project.  I’m absolutely delighted that the lid is now in place, and would like to thank everyone involved in getting us to this stage.”

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