Silbury's future? (1)

Silbury Hill 180

Image by juswin

nigelswift May 28, 2005 11:08:37

Those who object to what's happening at Silbury are misguided, ill-informed and don't understand. Or not. The fifth anniversary of the first collapse seems a good moment to decide, on the evidence.

Heritage Action's concerns about the choice of repair option seem to have been a bit late. On 3 March we suggested that the most unsafe, most expensive and most disruptive solution was looming, due to a research agenda.
http://www.heritageaction.org/?page=campaigns_silburyhill_crucialdecision

But the EH Advisory Committee minutes have just been published. They reveal that they had actually considered the matter just a week earlier and had indeed concluded that the construction of a new tunnel (and leaving it open!!) was the "preferable" option.
http://www.english-heritage.org.uk/FileStore/about-us/pdf/ehac/EHAC_minutes_Feb05.pdf

We had suggested that it was impossible for EH or the public to make a considered judgement on the basis of the published details. It seems that someone on the Committee agreed: "there was not enough engineering advice in the report" and "a paper on the engineering side of the project would be welcomed"

On the occasion of the fifth anniversary of the collapse, we wholeheartedly agree. It would be very welcome.

Yet despite this, the Committee felt sufficiently informed to be able to dismiss grouting as an option! We find this concerning. For years we have urged that this should be the lead option, on the grounds that it is the conventional technique and potentially far less damaging, far speedier and cheaper than tunnelling. The Committee dismissed it by saying it "had problems with further intervention and concerns about the additional boreholes". We wonder how "problems with further intervention" and "concerns about the additional boreholes" make this method unacceptable compared with a full scale tunnel and whether a specialist structural engineer has ever actually come out to say so.(The answer is no).

By contrast, the Committee appears to have been in possession of sufficient data and sufficiently confident of the scale of collateral loss (previously a matter of pure speculation) to be able to opine that creation of a vast new tunnel "was preferable". Indeed, even the cost seems to have been calculated: £600,000 (and who believes that won't quadruple?)

Furthermore, their preference was for the tunnel to be kept open (over a timescale yet to be defined). Previously, this has been mooted only in connection with the need to monitor it, but a brand new possibility appears to have been put to the Committee: "keeping the tunnel accessible for visitors"! We are entitled to wonder - is this the key to their otherwise puzzling statement about the cost of constructing and maintaining the tunnel:

"Costs would be spread over a number of years, as it would be impossible to find the money in the short term. A five year plan could be considered and it was possible that other organisations (or companies) might share the costs if they wished to join in and be seen to be helping with conserving the environment".

That extraordinary, insolent statement should be seen against this:
Zero evidence has come to light, including that presented to the Peer Group Review, published in British Archaeology, displayed on the EH website, supplied direct to us or expounded by an independent structural specialist, suggesting that tunnelling should yet be considered other than an option or that grouting should be rejected. Furthermore, in our view tunnelling is not "preferable"; it is a dreadful last resort, if all else is impossible. We find the Committee's view that constructing a vast open tunnel to the centre of the hill "posed minimum intervention in terms of further damage to the monument" absolutely wondrous both in layman's terms and when measured against the published loss estimates, 60,000 cubic feet!

nigelswift May 28, 2005 11:10:45

Replying to nigelswift

In summary, my amateur ill-informed fear is that the Committee has already been persuaded along a particular route - vast disruption and cost, but lots of research fun - without the least reference to the public and on the basis of an admitted incomplete knowledge of the facts relating to ANY of the options.

The British Archaeology articles reeked of a research agenda, even to the extent of "favourable" presentation of figures. So does much other material and testimony we have obtained.

As a simple layman I fear our monument is to be annexed by those with a vested interest in their own research agenda. Either I'm right or wrong. Please read the minutes and decide. Is a tunnel necessary? Is EH skint? Is there evidence we might end up with a privately financed walk through as the price for a few people achieving their research ambitions?

I'll be delighted to be shown, not told, I'm entirely wrong.

Pilgrim May 28, 2005 21:10:11

Replying to nigelswift

Hi, Nigel

I can't get your link to the EH Minutes to work (they can't have removed them, surely?). Any chance of checking the link from your end and reporting back?

Cheers

Peace

Pilgrim

smallblueplanet May 28, 2005 22:02:38

Replying to nigelswift

Page 3 *ITEM 5 – SILBURY HILL: OPTIONS FOR STABILISATION (EHAC 2005/4)

5.1 The Committee was asked to consider three options for the future of Silbury Hill following the collapse of the vertical shaft: 1) do nothing; 2) fill the voids; 3) support the voids.

5.2 It was confirmed that the first option did not include any backfilling at the top of the mound as extra weight on the polystyrene blocks would have a detrimentaleffect further down the shaft. Filling the tunnels would cover the earlier Merewether tunnel as best as possible although it was unclear how much of this had been backfilled already.

5.3 Health and Safety checks would need to be in place particularly in the case of unauthorised public access.

5.4 It was agreed that work already carried out had advanced our understanding of Silbury Hill. There were complex issues and a legacy from the Atkinsonexcavations. The meeting at Devizes on 28 September 2004 had been useful in demonstrating the extensive research EH had undertaken and that EH had taken on board a wide spectrum of opinion.

5.5 The Committee agreed that the paper presented was helpful in enabling them to reach a decision and that EH had taken time to consider the various options. Option 1 presented an unknown risk to the monument; option 2 had problems with further intervention and concerns about the additional boreholes; and option 3 posed minimum intervention in terms of furtherdamage to the monument. The variation to option 3 which proposed keeping the tunnel accessible for visitor access was a concern because of the frequentair exchange. There was, however, a need for monitoring the stability of the repairs over a timescale yet to be defined.

5.6 The key was in not moving too quickly but in taking time to consider the best option. There was no planning application that necessitated the need for speed, but there was a lot of local interest and frequent radio coverage.

5.7 It was acknowledged that there were still a lot of unknown factors and risks in further intervention. For option 3 to be recommended, there needed to be a demonstrable link to management-critical research objectives. The cost of the project would be in the region of £600k plus on-going maintenance costs. It was suggested that a combination of all these factors meant clarifying the uncertainties before doing anything further.

5.8 Costs would be spread over a number of years, as it would be impossible to find the money in the short term. A five year plan could be considered and it was possible that other organisations (or companies) might share the costs ifthey wished to join in and be seen to be helping with conserving the environment.

5.9 The area is also a Site of Specific Scientific Interest (SSSI) and, as such, consent will be needed from English Nature for potentially damaging operations. None of the options, however, sounded intrinsically damaging to the chalk grassland interests of the SSSI. EH should maintain close contact with the Conservation Officer at English Nature, Patrick Cashman.

5.10 The comment was made that there was not enough engineering advice in the report and that it was necessary to establish how, for example, the timber and iron from previous interventions would perform under further construction work. A paper on the engineering side of the project would be welcomed.

5.11 <b>The Committee agreed that: i) Option 3 was preferable, more engineering advice was needed andthere was no need for haste; ii) the site should be open for monitoring purposes and in situ preservation would be one of the key strategies in future. </b>

Silbury's future? (1) lock

Silbury's future? (1)