By Ashley Karen
Work on the secondary line Tideway’s 4.5km Greenwich connection tunnel between Greenwich and Bermondsey has been completed.
The secondary lining completion is another significant milestone for London’s “super sewer” project to construct a 25km long stormwater storage tunnel.
The Greenwich connection tunnel is expected to resolve the issue of sewage overflow into the Deptford Creek and River Ravensbourne and control the flows into the main Thames Tideway Tunnel.
Tunneling on the Greenwich connection tunnel was finished in April 2022 when a TBM (tunnel boring machine) broke through into the shaft at Tideway’s Chambers Wharf site.
A team has been installing the 180mm-thick concrete lining over the past months, which will secure the tunnel lasting for at least 120 years.
Six shutters were employed to create a circular mould for the concrete with 104 lining cycles carried out in total on the connection tunnel, which begins at Greenwich Pumping Station and extends to Chambers Wharf, where it connects to the new super sewer.
The thickness of the concrete lining was decreased during the design stage – making significant carbon savings – for minimizing the impact of the work.
During the lining work, which started in July 2022 and was finished last month, an innovative bogie system was employed to allow the shutters to be driven independently without depending on the traditional rail-mounted system.
Aggregate for the secondary lining concrete was moved to the site by barge-reducing lorry movements to the Chambers Wharf site. While the concrete was pumped and transported by locomotive concrete mixers between the batching structure located within the noise enclosure and the circular shutter in the tunnel below ground.
The last section of the central tunnel is now being secondary-lined between Chambers Wharf and Abbey Mills Pumping Station.
Mousa Khalifeh, Deputy Delivery Manager, Eastern section claimed: “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.”
He continued: “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.”
Recently, Tideway marked another milestone earlier in August, when cofferdams were removed from locations comprising Albert Embankment in Vauxhall and King Edward Memorial Park in Wapping.
