Nearly twomillion cubic metres of sand are being shifted to a stretch of eroding Norfolkcoastline in a radical plan to save it from the sea.
The 6km-longdune will protect Bacton Terminal, which supplies one third of the UK's gas,but is teetering just metres from a cliff edge.
The £20mproject should also act as a defence for two nearby villages - Bacton andWalcott.
It is thefirst "sandscaping" scheme on this scale to be carried out in the UK.
It has beendesigned by Dutch engineering company Royal HaskoningDHV.
Once thesand has been shifted, a combination of wind, waves and tides will "movethe sands to where it needs to be," said the firm's coastal managementadviser Jaap Flikweert. This will "provide 15-20 years ofprotection".
The schemehas just started, and it is expected to take about five weeks to get all of thesand into place.
In a 24-houroperation, carried out by the Dutch maritime company Van Oord, a dredgingvessel is collecting the sand from further along the coast at a licensed sitewhere sediment is currently extracted for concrete.
It thensails to Bacton, connects to a giant pipe, and pumps a mixture of sand andwater onto the shore at a rate of 10,000 cubic metres per hour. Bulldozers anddiggers then shift the sand into place.
Oncecomplete, the dune will stretch for 6km (4 miles). At its highest point, itwill stand 7m-high (22ft) and extend up to 250m (820ft) out to sea.
"Itwill turn back the clock to what the beach was like about 30 years ago,"says Mr Flikweert.
The Norfolkcoastline is losing land every year as part of natural geological erosion. Whenbig storms occur, several metres of coastline can vanish at once.
Homes invillages like Happisburgh have already started to be lost to the sea - and manyother coastal communities are facing a similar fate.
When BactonGas Terminal was built in the 1960s, it was situated more than 100m back fromthe sea. Now some parts of the complex are just 10m from a cliff edge.
Typically,to protect national infrastructure like this, vast barriers made of concretewould be used.
But doingthat, said Mr Flikweert, would have had disastrous consequences for thevillages of Bacton and Walcott. They are located a few miles down the coast andalready face a significant risk of flooding.
A wall in frontof the terminal would stop the sea from removing sediment there, causing it totake sediment from the villages instead.
"So thebeach erosion there would go on even more quickly," said Mr Flikweert.
Instead, theteam turned to sand, inspired by a large-scale experiment in the Netherlandscalled the Zandmotor.
In 2011,Dutch scientists placed 20 million cubic metres of sand along a 1km stretch ofcoastline in South Holland.
The sedimentdrifted and moved with the currents, but it did the job of safeguarding thecoast from erosion.
It wasinitially thought the dune might last for 20 years. But a recent analysissuggests the defence could last for twice as long.
Carola vanGelder-Maas, from the Dutch government's water management body Rijkswaterstaat,said:
"In the beginning, we never expected it to have a life span of 40years.
"Weonly 'lost' 1.5 million cubic metres of sand during these eight years. Butsediment is still being transported, so the Zandmotor is still stretching andcontributing to a more natural way of coastal maintenance."
The schemein Norfolk is on a smaller scale, but the hope is that it could offer 15-20years of protection to the terminal and villages. After that, the sand wouldneed to be replaced.
The teamfrom Royal HaskoningDHV said the shape of the dune will change over theduration. And after big storm events, it could look like the sand is lost - butthe natural movement of the sediment should rebuild it.
Mr Flikweertsaid it is not a permanent solution, but it does "buy time for thecommunity".
"Theexperience with the Dutch Zandmotor shows that the concept works - we'reconfident ours will work," he said.
The £20mcost of the scheme is mainly covered by the Bacton gas terminal operators, with£5m from the Environment Agency and £0.5m North Norfolk District Council.
The expenseof flood defences is something that many communities around the UK are havingto consider.
And Dr SallyBrown, from the University of Southampton and University of Bournemouth, saidthe problem will get worse.
"We'regoing to see more possibility of flooding and more erosion with climate change,and we'll see the need for more flood defences.
"Inplaces that we're going to choose to protect, defences are going to get biggerand they're going to be very different from what we see now."
But whilethe money might be more readily available for protecting nationalinfrastructure such as Bacton or large cities, Dr Brown warns that others couldlose out.
"Weneed to invest a lot to keep the coasts exactly as they are at the moment, andone of the biggest challenges is that we can't keep doing that in places thatjust protect a few people, or maybe in places where flood risks only affect afew houses, so there are going to be some really hard choices to come."
Many will bewatching Norfolk's sandscaping project to see if it could work for other partsof the coast.
Sue Brooks,professor in coastal geosciences, from Birkbeck, University of London, said:"With the sandscaping scheme… there has been a shift from hard defendingthe coast to more of a nature-based solution. Put sand there - and let naturedo with it wants.
"Wedon't know at this point how successful this scheme is going to be, but atleast we're giving it a go, which is a really radical new way of thinking aboutshoreline management."
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