The completion of the 4.5km Greenwich Connection Tunnel between Greenwich and Bermondsey has marked another major milestone for London’s super sewer.

Secondary lining of the tunnel to tackle the problem of sewage overflow into the Deptford Creek and River Ravensbourne and direct the flows into the main Thames Tideway Tunnel is now finished.

Over previous months, the team has been installing a 180mm-thick concrete lining to ensure London’s new super sewer will last for at least 120 years. Six shutters were used to form a circular mould for the concrete with 104 lining cycles carried out in total on the connection tunnel which starts at Greenwich Pumping Station and stretches to Chambers Wharf where it links with the new super sewer. To endeavour to minimise the impact of the work, the thickness of the concrete lining was reduced during the design stage making significant carbon savings.

During the lining work which began in July 2022 and was completed last month, an innovative bogie system was used to enable the shutters to be moved independently without relying on the traditional rail mounted system.

“Finishing the lining of the Greenwich Connection Tunnel brings us one major step closer to cleaning up the River Thames and by adding a second layer of concrete we ensure the tunnel is robust to last for the next century. Credit to the teams below ground who have continually improved production methods and efficiency and successfully managed to line the tunnel in just over a year,’ said Mousa Khalifeh, Deputy Delivery Manager, Eastern section.

Aggregate for the secondary lining concrete was transported to site by barge reducing lorry movements to the Chambers Wharf site, while concrete was pumped and transported by locomotive concrete mixers between the batching facility located within the noise enclosure and the circular shutter in the tunnel below ground.

The final section of the main tunnel is currently being secondary lined between Chambers Wharf and Abbey Mills Pumping Station.