Tunnellers finish 4-year Super Sewer dig close to schedule

The vast 25km drive and associated tunnelling on the Super Sewer came to a close when TBM Salina reached the Abbey Mills pumping station in East London this week.

Salina’s TBM team delivered some of the fastest progress in the final months of the drive bringing the forecast completion closer to the original date despite Covid delaying the overall project completion by an estimated nine months.

Last TBM Selina ended with a sprint finish

In total three runnelling teams have completed the historic drive. Due to section scheduling and access challenges only two of the six TBMs used to excavate the project were at work at any time.

Of the three main sections, Ferrovial and Laing O’Rourke overcame the most challenging ground conditions on the 7.6km central London sections coping with sand, gravel and chalk layers in the drive.

BAM Nuttall/Morgan Sindall/Balfour Beatty started the 6km West tunnel project first and finished first.

Thames Tideway CEO Andy Mitchell played a big role in promoting Site Operating Procedures for safe working during Covid

The first Covid-related countrywide lockdown hit this section hardest. At the time the TBM was under Hammersmith Bridge, requiring tunnellers to drive the machine to a safer location before shutting down all activity for 2-3 weeks.

The East works package entirely through chalk was completed by the Costain, Vinci and Bachy Soletanche joint venture. At times this team ran into dense boulder-sized flint on its journey to the final finishing line at Abbey Mills.

To celebrate the engineering feat, a live music performance will be stages today 70m underground in what is described as a symphony of percussion instruments, cello harmonics and piano.

Sir Neville Simms, Chair of Tideway, said: “Completion of tunnelling for London’s new super sewer is testament to the hard work and contributions of thousands of people and organisations, over many years – and it brings us closer to the ultimate goal of a cleaner River Thames.”

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