London’s Super Sewer now fully built after installation of enormous concrete lid

Posted on 22 Apr 2024 by The Manufacturer

Works to construct the Thames Tideway Tunnel – also known as London’s Super Sewer – including its tunnels and shafts, are now fully complete after installation of the final piece of the puzzle, a precast concrete circular cover weighing 1,200 tonnes and 24 metres in diameter.

The project is closer than ever to being commissioned and therefore starting to improve the health of the River Thames after Sarens, world leader in heavy lifting, engineering transport and crane rental services, installed the cover slab on top of the 70m deep shaft at Abbey Mills Pumping Station, Stratford in East London. The shaft at Abbey Mills is the point at which the Super Sewer connects to the Lee Tunnel, which will take the sewage flow out of London to the Beckton sewage works for treatment.

The Super Sewer is a 25 km-long, 7.2m diameter, sewer tunnel designed to dramatically reduce sewage pollution in the central London River Thames. In a typical year, tens of millions of tons of storm sewage spill into the River Thames but once fully operational in 2025, the new infrastructure will reduce those spills almost completely. The Super Sewer is being constructed by a joint venture of Costain, Bachy Soletanche and Vinci working for Tideway, the company building the super sewer for Thames Water.

Sarens was selected by the CBV joint venture for this operation which marked the completion of the major civil engineering elements of the project. Using a purpose-built SPMT mounted gantry crane, Sarens lifted and moved the cover slab into place during an operation lasting 5 hours. The cover slab is the heaviest piece handled on the Thames Tideway Tunnel project – even surpassing the lifting of Tideway’s six tunnel boring machines in the early stages.

The assembly of the SPMT gantry, which included main beams weighing 100 tons each, took four weeks. 50 trucks brought all the equipment to site from Belgium and Southampton. Coordination of the deliveries was critical as there was not room on site to store materials meaning they had to be incorporated into the gantry as they arrived at site. A CC2800 Crawler Crane was used to assemble the Gantry. Due to the very limited site space this crane was selected as it could assembly the entire gantry from one position.

The Thames Tideway project is a source of pride for Londoners, and Sarens work brings it one step closer to completion after eight years of work by 1000s of construction workers. The next step is to test the system, when live storm sewage flows will be diverted into the new infrastructure, but the capping of the Abbey Mills Pump Station shaft marks an absolutely critical milestone for the Tideway project and for London.

Robert Frost, Sarens’ engineer, said of the final lift: “This operation to lift, transport and place the cover slab was a complex operation, and required careful collaboration between various teams working on this project. I’m absolutely delighted that the cover slab is now in place and would like to thank everyone involved.”

The Sarens team has extensive experience in the UK. They have recently been able to support the construction of the Hinkley Point C power station using the SGC250 ring crane known as Big Carl, the largest land based crane in the world. Sarens has also undertaken the Process Module and Process plant movements and lifts for the FAST project at the Fawley refinery, the installation of a 5000te concrete culvert on the rail line close to Glasgow, as well the movement of a 4000te ship block for new Class 26 Frigates, and the installation of complete bridge decks over the A46 and the M56.

For more articles like this, visit our Leadership channel