Engineers from client, National Grid’s Gas Distribution strategic partner tRIIO, which includes consultant, Mott Macdonald and contractor, Skanska, are starting work on National Grid Gas Distribution’s biggest civil engineering project – a 330m long tunnel under the River Thames in London.A critical part of National Grid’s vital work to future-proof London’s gas infrastructure for the 21st century the project involves three of London’s most famous locations: the Royal Hospital Chelsea, Battersea Park and the River Thames. Engineers are preparing to sink a 30m deep shaft at each of the land locations ahead of digging the 330m long tunnel using a micro-TBM, operated remotely from above ground.
Thus far the project team have liaised with fifteen different organisations and secured almost 20 different permissions before getting the green light. The team have also been working closely with Thames Tideway regarding the nearby Chelsea Foreshore works, to ensure both projects can proceed together harmoniously.
The first shaft, which will have a diameter of 7.5m, will be sunk in the grounds of the Royal Hospital Chelsea between January and March 2017. Work will then shift to Battersea Park where the second shaft – with a diameter of 6m – will be sunk between April and August 2017.
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Tunnelling will start after the shafts have been completed and should be finished in 2018 after which the new intermediate pressure gas pipe will be installed.
Project Manager Andrew Hejdner said: “This is National Grid Gas Distribution’s flagship civil engineering project for the 2013-2021 regulatory period*
“We’re looking forward to getting started on the construction which has taken almost 12 months of planning.”
He added: “Designing a tunnel 330m long tunnel that runs 30m under the River Thames is fairly straightforward in tunnelling terms however to secure so many permissions and factor in Thames Tideway’s works in such a short space of time is an impressive undertaking.
“Our project team have done a fantastic job in designing the river crossing and securing the necessary permissions.”
Engineering Manager Stuart Donaldson, who will oversee construction of the project, said: “This is quite a bit different to the average gas mains replacement scheme to say the least!
“However the purpose of this project is the same – keeping people connected to safe and reliable gas supplies for cooking and heating.”
He added: “The project is going to leave a great legacy and help London maintain its status as a leading 21st century city.”
The tunnel forms part of National Grid’s £1bn investment in replacing ageing gas mains across the capital.