London’s new super sewer has been closed off to the city above at its most central point with a concrete lid now in place hiding the engineering marvel below it.

Tideway’s site in Nine Elms, Kirtling Street, is the point at which two tunnel boring machines (TBMs) were lowered 50m into the ground in 2018 to begin tunnelling on the 25km super sewer.

Travelling east and west, these two machines 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 – from which these two machines were launched now has its concrete cap fully constructed.

Ignacio Tognaccini, Project Manager at Kirtling Street, said: “Capping off this shaft is a fantastic moment for us on 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.

“Tens of thousands of precast concrete segment were lowered down to create the tunnel, with millions of tonnes of spoil removed and beneficially reused.

“We’re now closer than ever to our ultimate goal of cleaning up the River Thames.”

Beneath the concrete cap, the shaft will remain as a void, and will contribute to the 1.6 million cubic metre storage capacity of the super sewer network.

Earlier this year, the shaft at Kirtling Street served as the stage for a unique 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 system 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.

The shaft cap in an almost-complete state, picture taken in August 2023

This image, taken in the summer of 2018, shows the first of
Tideway's tunnel boring machines being lowered underground
at Kirtling Street in Nine Elms