Tideway’s site in Nine Elms is the point at which two TBMs were lowered 50m into the ground in 2018 to begin tunnelling on the 25km super sewer.
Travelling east and west, the two TBMs created the central section of the main tunnel between Fulham and Bermondsey.
TBM Millicent tunnelled the 5km toward Carnwath Road in Fulham, while TBM Ursula tunnelled the 7.6km journey toward Chambers Wharf in Bermondsey.
The shaft – around 30m wide and 50m deep – now has its concrete cap fully constructed.
Ignacio Tognaccini, project manager at Kirtling Street, capping off the shaft was a “fantastic moment” for the Tideway project.
“Work to excavate the shaft began many years ago, and it has been in almost constant use ever since, allowing our teams to create the central part of the super sewer,” he said.
“Tens of thousands of precast concrete segment were lowered down to create the tunnel, with millions of tonnes of spoil removed and beneficially reused.”
The shaft will remain as a void and will contribute to the 1.6 million m3 storage capacity of the super sewer network.
Earlier this year, the shaft served as the stage for an artistic installation called Loo Gardens, in which members of the public were invited to experience this symbolic representation of the future health of the River Thames.
Tideway will begin testing the new sewer next year, diverting live storm flows of untreated sewage away from the River Thames for the first time.
The system will be fully operational in 2025.