Bid to save Silbury Hill could cost £600,000 (From The Wiltshire Gazette and Herald)

Bid to save Silbury Hill could cost £600,000

THE collapse of infill at Silbury Hill has happened before and will happen again unless urgent action is taken to stabilise it, a meeting in Devizes heard on Saturday.

English Heritage had called the ticket-only meeting to discuss its preferred option for the future of Silbury Hill, the most ancient man-made structure in northern Europe.

It wants to enter the tunnel dug by a team of archaeologists in 1968 and back-fill it with chalk, also filling in the voids created during the various excavations of the mound since the 1776 tomb-raiding exploits of the Duke of Northumberland.

Amanda Chadburn, one of the English Heritage team who has been investigating the current state of the hill, said the appearance of the hole at the top of the mound in May 2000 had come as a shock to archaeologists.

There had been a further collapse in December 2000 after which the hole was given a metal cap supported by scaffolding. The hole is now temporarily filled with enormous expanded polystyrene blocks.

It had been well known that the Duke of Northumberland, searching for the legendary golden statue of King Zil reputed to be buried in the mound, had employed miners to dig a shaft straight down through the centre of the hill and had refilled it with branches topped with a chalk plug.

The situation was made worse by a subsequent tunnel dug into the side of the hill by workmen hired by Dean Merewether in 1849.

But during her investigations through the archives of various museums in the county, Ms Chadburn had discovered that the collapse of the central shaft had happened before.

She showed an aerial photograph taken in 1925 clearly showing a hole at the top of Silbury Hill, similar to the one that opened up in 2000.

She had also found letters referring to this hole that was eventually filled in by the Ministry of Works in 1936.

Archaeologist Fachtna McAvoy said boreholes were driven into the hill by English Heritage to carry out a seismic survey of its interior.

Cameras were lowered down these holes and archaeologists were appalled to see huge voids that had appeared in the 1968 Atkinson tunnel that was supposed to have been properly backfilled.

Bob Bewley, regional director of English Heritage, said it was important to enter the tunnels and make sure that all voids were properly filled to prevent any further collapses within the ancient monument.

But Nigel Swift, for the protest group Heritage Action, urged English Heritage to think again.

He told the meeting: "Re-tunnelling will destroy a lot of archaeology so we would have to have a lot of confidence that English Heritage knows what it is doing. We see no confidence in it."

He said English Heritage's own figures showed the damage caused by tunnelling would amount to 166 cubic metres and a better option would be grouting the voids from outside the hill by pumping in filler material.

Professor Chandler from Imperial College, London, said the hill was in no immediate danger.

He said: "The hill looks not too different from the way it looked when it was completed. Rabbits and badgers are doing more damage than anything else done to it over the centuries."

Mr Bewley said that invitations to tender were going out to prospective contractors over the next few weeks and the work was unlikely to be complete before 2007.

The cost has not been finalised but it is thought to be in the region of £600,000.