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Southern Gas Networks (SGN) is hoping to have tunnelled its way into the record books after completing a £20 million project to replace the undersea gas pipeline from the mainland to the Isle of Wight.
Engineers have drilled two tunnels up to 30 metres underneath the Solent seabed to lay a new 3.8km gas main from the mainland coastline at Lepe on the edge of the New Forest to Gurnard near Cowes, in what is believed to be the longest drill of its kind.
Gas is now flowing through the new dual pipeline, and has been connected with the existing network to provide a secure and continuous supply for the island’s 56,000 gas customers. The new pipeline officially opened on Friday, 23rd March. It replaces the three old lines, installed in 1966, from the mainland to Egypt Point.
The cross-Solent gas pipeline has taken 18 months to construct and follows four years of planning, involving surveys, trials and lengthy consultation with relevant authorities.
The complex under-sea drilling was completed using directional drills – specialised hydraulic machines which are operated from land.
They drilled two separate tunnels underneath the seabed from both sides of the Solent with the drill-heads meeting in the middle before the new gas mains were pulled through and the supply connected
A new pressure reduction station has also been constructed at Gurnard, regulating the pressure of the gas as it is distributed through the network across the island.
John Morea, SGN’s Chief Executive Officer, said: “While fulfilling their function perfectly well, we were aware the existing pipelines between the mainland and Egypt Point had a limited lifespan due to their age and the nature of their location, resting on the seabed.
“A new undersea pipeline, while complex to lay, was the logical step forward, so our planning began back in 2008 when we started working on the concept, and began our preparatory consultations.
“It was uncharted territory for us, due to the length of the pipeline under the sea, but we carried out extensive trials, including shorter drills to help cut out the risks, so we’re very happy to have completed it as planned and without disruption of gas supply to islanders.”
SGN has worked in consultation with many organisations to ensure the project was a success, including local authorities on the Isle of Wight and the mainland, environmental organisations, and local residents who were consulted extensively.
With the locations around the works designated as either Areas of Outstanding Natural Beauty or designated nature conservation sites, SGN employed specialist environmental consultants from the outset of the project, to advise on all mitigation measures required to protect the environment. Pre-emptive measures were taken to minimise the effects on wildlife and landscape, and drilling underneath the seabed enabled the project to avoid adverse impact on marine wildlife and marine navigation.
Local MP Andrew Turner officially opened the pipeline by unveiling a plaque. He said: “There are particular problems in providing a safe and reliable gas supply to the Island. This has been a technically challenging project and the new pipeline represents significant investment by Southern Gas Networks. I welcome it as it will ensure that Island households have a reliable supply of gas both now and for the future.”
SGN is now waiting for official recognition from the Guinness Book of Records that the project is the longest directional drill of its kind.