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Silbury Hill 180

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Silbury updates

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fool on the hill Jul 27, 2007 20:49:06

Replying to Littlestone

I was one of the people fortunate enough to be invited on one of the EH tours into the excavations last weekend (boo, hiss, traitor etc) and it was one of the most amazing and honoured experiences of my life. It was also quite shocking to see the extent of damage from the inside and I can definately confirm that EH were right in opening up the tunnel to repair this. The problem lies at the centre, where Atkinson's workings join Northumberland's shaft. At this point the workings were not so much a tunnel as a canyon. Yes Atkinson's supporting rings are still in place, but the problem was they are not supporting anything for a good distance from the centre.
As you know from the EH updates the roadstone backfill only went in so far, leaving a void behind. Unfortunately from this point the underside of the hill was not chalk, but a chalk, clay mixture which has subsided and is what caused the dig to slow. This, and the surrounding sides was sodden when we were in there, showing the extent of water penetration. Because Skanska did not want to introduce to much extra modern intrusion to the dig they were using the exisiting Atkinson rings as shuttering supports, with shuttering plywood, steel sheets etc over the top to protect the excavators. At the centre, where the clay 'collapse' had been, there was of course a void above these roof supports, which already had a good mound of loose chalk piled on it, which presumably must have happened from the time the sheets had been put across to when we went in (2 weeks max?). It is my guess that it is this area that has become unstable and the collapse is spreading upwards, like taking the mould away from an unstable jelly.
As to apportioning blame, I feel that is a pretty pointless exercise. Without doubt the root cause of this is the water seeping down through the hill causing failure and collapse of material around an exisiting large void. Were EH right to open the tunnel, in my view most definately so? Who could have predicited the horrendous wet weather we have had recently? But plenty of people (including some on here) did mute the posibility so should contingencies have been made? Hindsight is a wonderful thing. I hope it is not too late to put up 'the brolly' and to backfill as safely as possible.
We were allowed to take photographs in the hill but EH did request that we would not publish them on the interweb so I hope the above will give you a good image.

the fool

fitzcoraldo Jul 28, 2007 08:26:45

Replying to fool on the hill

cheers for that fascinating account,
It sounds like awfully risky work, relying on shuttering instead of pinning the walls and roof of the tunnel. I just hope the engineers and archaeos can come up with a solution that will allow them to safely re-enter the hill and continue with their work.

no boo-hissing from this corner
fitz

Littlestone Jul 28, 2007 11:14:55

Replying to fool on the hill

As to apportioning blame, I feel that is a pretty pointless exercise. Without doubt the root cause of this is the water seeping down through the hill causing failure and collapse of material around an exisiting large void.

Of course blame should be apportioned, and it should be apportioned to those at English Heritage for not addressing the problem since the hole at the top of Silbury first appeared in 2000. For seven years water has seeped into the structure because of inadequate measures taken since then, and even now English Heritage are doing nothing to prevent further seepage from the heavy rain expect over the weekend.

It's not rocket science; a temporary cover, as ocifant suggested above, could be put up today. Oh, sorry, it's Saturday today isn't it - those at English Heritage responsible for this fiasco are probably taking the day off. Talk about Rome burning.

Let me ask you this; if English Heritage do not provide a temporary cover, immediately, and further collapses do occur as a result of that negligence, will you still be happy not apportion blame to those responsible?

moss Jul 28, 2007 11:23:17

Replying to fool on the hill

fool on the hill wrote:

upwards, like taking the mould away from an unstable jelly.
As to apportioning blame, I feel that is a pretty pointless exercise. Without doubt the root cause of this is the water seeping down through the hill causing failure and collapse of material around an exisiting large void. Were EH right to open the tunnel, in my view most definately so? Who could have predicited the horrendous wet weather we have had recently? But plenty of people (including some on here) did mute the posibility so should contingencies have been made? Hindsight is a wonderful thing. I hope it is not too late to put up 'the brolly' and to backfill as safely as possible.
We were allowed to take photographs in the hill but EH did request that we would not publish them on the interweb so I hope the above will give you a good image.

the fool

Hi, Thats an interesting account, you were very lucky to go into the tunnel, envy you somewhat.
As you say the rain has been both heavy and unpredictable, and apart from Silbury has caused untold damage elsewhere, but if water was leaking down from the top surely a 'brolly' before the work commenced, or even earlier still, would have countered god's need to drown the landscape and cause damage to Silbury. When you take tiles off the roof of a house its normal to put up plastic sheeting to protect the wooden rafters that are exposed.
Hindsight is indeed a great gift but the practical act of prevention would have made sure that the gods and unseasonal weather were'nt the winners. Lets hope Silbury can be backfilled safely for all concerned in the endeavour, I wish them well in what is turning out to be a dangerous undertaking.

Robert Carr Jul 28, 2007 13:55:22

Replying to fool on the hill

Thanks Fool on the Hill for your report. Sounds dangerous in there!

fool on the hill wrote:

As to apportioning blame, I feel that is a pretty pointless exercise.

Yes I agree. That would be like blaming the people who have stinky water in their houses for their own predicament because they did not take adequate precautions. And who on earth would do that?

goffik Jul 28, 2007 19:47:50

Replying to fool on the hill

Excellent report, FOTH... Thank you!

I'm sure you'll get no booing or hissing here... It's jusr nice to get a report from the ground, so to speak... And it's a damn sight more information thatn we've had from anywhere else! :o) We all wish the workers the best of luck and hope all predicted collapses are far from reality...

Although you're not allowed to post the imaegs on any websites, are you allowed to show them to other people who promise to also not post them on any websites, by email, say? I'd be very interested in seeing them. Just out of curiosity, nothing more... As Moss said - I think a few of us will be slightly envious of your visit! ;o)

G x

nigelswift Jul 28, 2007 22:09:45

Replying to fool on the hill

"We were allowed to take photographs in the hill but EH did request that we would not publish them on the interweb"

How very strange.
And how fortunate they didn't invite me to go in (fat chance!).
I'd have ignored their request, taken a vast number of photographs and spread them as far and as wide as I could to the public, whose hill it is and who are funding the whole thing.

Pilgrim Jul 28, 2007 23:53:21

Replying to fool on the hill

Hello fool on the hill,

Thank you for your post.

fool on the hill wrote:

Lucky. Not sure if I would have had the balls to go in there.

Whilst in no way wishing to prolong this agony, I would just lik to point out that the it took EH from 29 May 2000 to 16 August 2001 to get something other than a metal plate over the crater on the summit; a crater which had appeared as a consequence of heavy rains over the preceding weeks........aren't we supposed to learn from experience?

fool on the hill wrote:

We were allowed to take photographs in the hill but EH did request that we would not publish them on the interweb so I hope the above will give you a good image.

Thus I find quite incredible. If the money for the restoration of the Mound is coming from the public purse, what right have EH to decide that this information is to be managed in such an overly controlling manner? It begs the question; whose information is it? This edict means that just those in the know get to see what is going on; the fact that people have been concerned with the state of Silbury for years means absolutely nothing to EH. Cynical Me says that they'll release this information once they have imparted their own spin on to it. It already sounds like Atkinson is becoming a sacrificial lamb...

I'm sorry; I'm feeling angry and short-changed right now. We're paying for this in so many ways.

Peace

Pilgrim

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