The team behind the £100 million gas pipeline project beneath the River Humber have bid a fond farewell to Mary, the 160m tunnel boring machine.
Having completed the 5km subterranean journey from Goxhill to Paull last month, she has been dismantled and lifted to the surface, ready for shipping back to Germany and her next tunnelling challenge.
National Grid is joined by project partners Skanska, PORR and AHak on the delivery, which has seen 160,000 tonnes of material – mostly chalk – excavated over the past 18 months.
Steve Ellison, lead project manager for capital delivery with 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.
“Mary has completed a fantastic feat of engineering and it’s great to see her on her way 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 River 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 pipeline replaces a trench laid pipe - part of the country’s gas transportation infrastructure, connecting to storage at Easignton - that had become exposed.
In the spring, two hydraulic thrust machines will start the epic task of carefully pushing eight huge 610m long and 850 tonne sections of pipe on rollers into the new tunnel from the Goxhill side. The pipes will be pushed 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 5km of pipeline is installed beneath the river. At completion it will be the longest hydraulically inserted pipe in the world.
As for the excavated material, it has been graded and re-processed at the Goxhill slurry treatment plant and is being used to help restore a former quarry nearby.
