London ‘super sewer’ now fully built

The Thames Tideway Tunnel is a 25km-long sewage tunnel designed to dramatically reduce sewage pollution in the River Thames.

Tideway said that in a typical year, tens of millions of tonnes of storm sewage spill into the Thames. Once fully operational, the new infrastructure will reduce those spills almost completely. 

The construction was reported as completed after the lifting and addition of a 24m-wide circular concrete ‘lid’ over the shaft at Abbey Mills Pumping Station in Stratford, a process which Tideway said took around five hours.

In a statement, Andy Mitchell, Tideway CEO, said: “This is the moment we’ve all been waiting for. 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. 

“There is still work to do – 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.”

Tideway has now built the full 25km, 7.2m-wide main tunnel, a 4.5km connection tunnel in south-east London, and a 1.1km tunnel in south-west London. 

The shaft at Abbey Mills is the deepest on the project at 70m, and is the point at which the super sewer connects to the Lee Tunnel, which was completed in 2016. 

Robert Ricketts, Tideway’s project manager at Abbey Mills Pumping Station said: “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.”

Following the successful delivery of this final milestone, Tideway will begin the process of commissioning the system before looking ahead to bringing it into full operation in 2025. 

The company said the commissioning process will likely begin over summer when live storm sewage flows will be diverted into the new infrastructure, essentially protecting the River Thames for the first time. 

Tideway will also continue its architecture and landscaping works at various sites along the route of the tunnel, including Blackfriars, Victoria and Chelsea, with the aim for these sites to become ‘completely new areas of public realm,’ reclaimed from the Thames and offering an entirely new vantage point of the city. 

The eastern section of the Tideway project is being delivered in partnership with Costain, Vinci Construction Grands Projets and Bachy Soletanche.