SILBURY PROJECT NEEDS A HOLE NEW APPROACH
BY BARRY LEIGHTON B.LEIGHTON@BEPP.CO.UK
08:00 - 28 July 2007
Vital work to protect Silbury Hill from collapse has been halted after experts discovered potentially disastrous new holes inside the mound.
And specialists tunnelling into the 4,600-year-old manmade mound, described as Europe's answer to the Great Pyramid, say the situation has been compounded by the recent downpours.
The team involved in a £600,000 project to make the mysterious Wiltshire landmark safe were on Tuesday told to stop work by Health and Safety officials because it had become too dangerous.
Now it is having to completely reassess the operation to safeguard the 130ft-high monument, with the project likely to be extended by several weeks and cost many thousands more than planned.
Project manager Robert Harding yesterday admitted it had been a blow and the team was now looking to introduce new methods of completing the unique scheme.
He said: "Unfortunately, there are voids inside the hill that are much bigger than we expected both near tunnel we have been following and around the central chamber."
He said some material had collapsed into the tunnel and chamber, possibly as a result of the wet weather dampening the clay.
The project to make safe the hill, which occupies five- and-a-half acres of the Avebury World Heritage Site, was launched in 2000 when a gaping hole opened at the summit.
Heavy rains had exposed the top of a vertical, 100ft mining shaft dug by treasure hunter the Duke of Northumberland and his team of Somerset miners in 1776.
Hi-tech studies have since revealed further problems as a result of horizontal tunnels dug by John Merewether, the Dean of Hereford, in 1849, and archaeologist Professor Richard Atkinson in 1967-68.
The aim of the new project was to properly backfill all the previous tunnels and voids inside.
Since May, Mr Harding's team has been burrowing into the side of the hill following the Atkinson tunnel and using some of the arches installed 70 years ago.
After 85 metres it reached a central chamber in the heart of the structure where it became apparent that there were gaps that could prove dangerous, both to the hill's stability and the project team.
Mr Harding said team members would probably have to dig a new tunnel within the Atkinson tunnel using their own supports.
This would extend the project for several weeks until well into October, he said.
An English Heritage spokesman said: "Our expert archaeologists and engineers are developing a solution to take the project forward, with the aim to stabilise the hill for the long-term. We will issue a new programme for the completion of the works as soon as possible."
Last night Lord Avebury, whose grandfather permanently leased Silbury Hill to the nation more than a century ago, said: "Obviously, it's a very worrying situation. English Heritage told me they have had to stop because of technical reasons.
"The rains cannot have helped the situation. The stability of Silbury Hill is of greater concern now than ever."