New gas pipeline under the river Humber
The 160-m long tunnel boring machine – Mary – which has been digging a tunnel to house a replacement gas pipeline 30 m beneath the River Humber, completed her journey on 10 September, achieving breakthrough into the shaft at Paull on the north bank of the river. This marked the end of her 18-month journey from Goxhill on the south side.
The 3.65-m diameter and nearly 5-km long tunnel (pictured), the first to be constructed beneath the River Humber, will carry a pipeline which can provide up to a quarter of Britain’s gas supplies. During her journey, Mary excavated approximately 160,000 tonnes of material, mostly chalk, which has been transported back to the surface, graded and re-processed at the Goxhill slurry treatment plant.
Next spring, two hydraulic thrust machines will start the task of pushing eight huge 610-m 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 complete, it will be the longest hydraulically inserted pipe in the world, says National Grid.