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Layman's Worries 1

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Steve Gray S
Steve Gray Dec 8, 2003 14:32:50
Replying to nigelswift

From my layman's perspective it seems that a cheap, quick, and archaeologically sound approach would be to line out the existing hole with geotextile (permeable membrane) and then fill the hole with chalk. That way the geotextile would form a boundary layer to differentiate the fill material from the original, but the general structure of the hill would have been restored. In the future, if someone comes up with a better way to do it, it's a fairly easy job to dig out the chalk fill and remove the membrane.

N nigelswift
nigelswift Dec 8, 2003 15:06:06
Replying to Steve Gray

Geotextile, yes that was mentioned as having been used. That's probably the suspected "sleeve" I mentioned.

I agree about the chalk. It's a standard procedure to use a fill that's of similar porosity and density and thermal expansion characteristics as the surrounding rock, for obvious reasons. They don't use polystyrene, for the same obvious reasons...

In the end, they'll use this type of technique
http://www.ukqaa.org.uk/CaseStudyMonsHill/CS3-MonsHillSept2001.pdf
but with a chalk based grouting. It will be pumped in and will fill every nook and cranny and will be coloured so that posterity will know which it is. This solution, used on thousands of collapsing caverns in the West Midlands has been available all along.