Pipelines' rapid progress across country

Checks carried out and ground planted at speed after huge steel snakes to bring Norwegian gas from coast buried Chris Benfield There have been bigger civil engineering projects, but not many that you could watch in progress from the top deck of buses across Yorkshire.

Many of us have had a glimpse of one of the sections of gas pipeline which have been snaking west, since April 1, from Pannal, near Harrogate, and Ganstead, just north-east of Hull – but not for long. The speed at which these huge steel snakes are nowadays made, buried and planted over, is a reminder of the power of technology.

In the 200 years since coal gas was first fed through hollowed wood to a line of street lamps in London, pipeline construction has become

a science at the heart of modern economics.

Already the Pannal line is at Skipton, more than half way to its destination at Nether Kellett, near Carnforth, on the other side of the Pennines; and the team that started at the Hull end can see its destination at Asselby, near Goole, on a clear day.

They have been completing nearly four kilometres a week each. And that is to triple-checked standards based on the expectation of 60 years of use.

Could our leaky water companies hit the same stand-ards? They could, but it costs something like 1,000 a yard.

One of the secrets of the speedy progress is planning. It took two years in the office to prepare for a summer on the ground – checking routes; applying for permissions; negotiating with land- owners and water suppliers, drainage authorities and highways agencies; doing sums; and placing orders.

Nearly 150 kilometres (90 miles) of 48in steel pipe from Germany is being trucked from Hull and Goole into the middle of farmland and moor – and that is only part of the total project. Miles of temporary road have been laid to carry the pipes and the machines which will lift them and bend them and put them in trenches dug over hills and holes drilled under rivers and roads and railways, without even pausing what happens above, most of the time.

The working way is usually 43 metres (141ft) wide, although it had to narrow to two (about two yards) to go through a hedge with a conservation order on it, south of Beverley.

The topsoil is scraped back, then a trench of precise depth – so everyone will always know exactly where the pipe is – is dug in the subsoil. So the trench line follows the contour of the subsoil and the pipe has to be bent to sit tightly in it.

While this is going on teams of archaeologists and geologists are examining the exposed earth for anything they want a closer look at. For various reasons most of the big pipelines so far have been laid north-south and the east-west cut has aroused a lot of scientific interest. Some exhibitions of the findings are in preparation. Meanwhile nobody wants to say too much.

"You might think metal-detecting is a dead hobby until word of one of these digs gets out," says a supervisor from National Grid, which runs inter-city distribution for both gas and electricity. "Keeping the amateurs out is a nightmare."

The bogeys in the nightmare are the health and safety police. Everyone knows someone who has been run off a site because a worker, visitor or even trespasser has been snapped without a hard hat.

Once the pipe is in the trench the soil is minced – to save importing a lot of sand for underpinning – and tamped back in the order it came out in. Then the botanists are called in to supervise replanting, using saved roots and seeds. Roadways are lifted, walls rebuilt and ditches reconnected.

The actual construction is easy in comparison.

Out on the front line in East Yorkshire, where everyone is covered in tiny black flies from the rape fields, National Grid gives way to contractor Murphy Pipelines. Over at Skipton it would be a French company, Entrepose.

Most of the men are travelling specialists, working 12 hours a day, six or seven days a week, during the "pipeline season" and bestowing bonuses on sandwich shops, pubs and B&Bs wherever they pass. They have the air of a travelling army and their group jokes are woven through the machinery and the rules they work with. The weld inspection team, using ultrasound and computers to check every joint, travels in a van labelled Mumbo Jumbo Voodoo Combo. The Sunday Sport calendar lives here and an arm tattooed with the entire Simpson family is a typical bit of bling.

"It's a lifestyle," says Vaughan Crawford, 33, National Grid's project supervisor on the Ganstead-Asselby run. For once he is living at home, in Anlaby, near Hull, but does not expect to see much of it, apart from his bed, until October. He doesn't want to do an interview – "That's why I'm an engineer."

But he does say: "The most satisfying thing is coming back in a year or two and finding it hard to tell where you have been."

The point of the pipeline is a vast natural-gas reservoir called Ormen Lange, in Norwegian sea-bed. More than 1,200km (720 miles) of undersea pipe will take the gas to Norway and then across to Easington, on Spurn Point, which is already a North Sea gas land-fall. The new on-shore line should link up with it, at the end of 2008, and take the gas across to its Lancashire destination via Ganstead, Asselby and Pannal.

All these locations are nodes on the existing high-pressure transmission network and the 250km of new line will connect those that already run north-south down the east and west sides of the country. By the end of this decade it is expected that 20 per cent of UK gas supplies will come via the Norwegian link.

chris.benfield@ypn.co.uk