Thames Water linked its 9.3km ring main extension to the original 80km circular ring main shaft beneath London yesterday.
The £95M project to build Britain’s longest tunnel will boost the quantity of water that can be carried around the capital.
Morgan Est’s Project Manager Daljit Dhanda, said: “The entire team has done extremely well in delivering this tunnel. It has been a reliable drive and we have had good steady progress in often challenging conditions.
“The project has been undertaken in a quiet residential area with work continuing 24-hours a day, five days a week.
“Through constant monitoring of noise levels, effective mitigation measures and a professional disciplined workforce we have ensured the agreed constant levels were not exceeded and have minimised our impact on the local environment.
“The breakthrough itself went extremely well and is testament to the consistent dedication and hard work of our team,” he said.
The breakthrough by contractors Morgan Est completed the northern extension from Stoke Newington to Islington.
The southern section from Honor Oak to Brixton will complete next month.
Thames Water’s project manager for the northern extension, Rachel Whiteman, said: “Both new tunnels, one to the north and one to the south of the River Thames, will have the combined capability of carrying an additional 500M litres of water each day.” The extensions are long, driven by tunnel boring machine 45m below the surface.
The event happened yesterday after 12 months of tunnelling, which began at Thames Water’s Stoke Newington Reservoir in Hackney, and was watched by a select party of Thames Water and Morgan Est representatives.
The finished 2.6m diameter concrete-lined tunnel will link the water treatment plant at Coppermills with the Thames Water Ring Main ensuring greater resilience of London’s potable water supply.
In addition to the main tunnelling work, the contract involves the upgrade of associated services and the construction of two deep shafts to depths of 50m. The 4.5km length of tunnel connects these two shafts with further branch tunnels constructed at both ends to allow connection to the existing network. The diameter of the launch shaft is 10.67m and the diameter of the reception shaft is 7.5m.
The project is scheduled for completion in Spring 2010.