A huge tunnel boring machine which is creating space for a new gas pipeline under the River Humber has completed its 5km journey.
The machine, affectionately called ‘Mary,’ is 160 metres long, and has been tunnelling under the estuary for 18 months.
On Tuesday afternoon, the boring machine broke ground at Paull in Holderness, completing a remarkable journey from Goxhill in North Lincolnshire.
Steve Ellison, lead project manager at National Grid, said: “Completing the tunnel beneath the Humber is a major milestone for the project team and our project partners.
“It’s the first time a tunnel has been constructed beneath the River Humber and a fantastic achievement for everyone involved.
“Over the next few weeks we’ll be dismantling the tunnel boring machine and lifting her out of the ground in sections, ready to be transported back to Germany, where as much as possible will be refurbished and renewed to get her ready for her next tunnelling job.
“The next steps for us here under the Humber involve clearing the pipes, cables and ancillary equipment that has been servicing the tunnel boring machine and preparing for the world record breaking pipeline installation early next year.”
The new 5km-long tunnel under the River Humber will carry a vital pipeline which can provide up to a quarter of Britain’s gas supplies.
During her journey under the Humber, ‘Mary’, the size of approximately 11 double decker buses in length, has excavated approximately 160,000 tonnes of material – mostly chalk.
That material was then carefully transported back to the surface, graded and re-processed at the Goxhill slurry treatment plant.
The excavated material is being used to help restore a former quarry nearby.
In spring next year, two hydraulic thrust machines will start the huge task of pushing eight 610-metre-long sections of pipe into the new tunnel from the Goxhill side.
The pipes will be pushed on rollers at about one metre per minute into the tunnel, which will have been flooded with water to aid installation.
When one pipe section has been installed, the next will be moved into position, welded to the one in front, and the push will continue until all five kilometres of pipeline is installed beneath the river.
When complete, it will be the longest hydraulically inserted pipe in the world.
National Grid was awarded the £100m contract to build the tunnel in a joint venture made up of Skanska, PORR Bau GmbH and A. Hak.
