http://www.aditnow.co.uk/documents/Old-Gunnislake-Copper-Mine/oldgnslkrpt.pdf 

I was reading this and was utterly flabbergasted by the lengths they went to in this report.

Quite clearly, the problem at Old Gunnislake mine is due to fluctuating water in the workings due to a blocked adit. A part of the problem is that the adit is driven along a crosscourse which has run in. We are not talking major distances. Probably in the order of 40ft or so, until it intersects the main workings.

The conclusion of the report is pretty alarming, with catastrophic blockage failures, holes opening up and pretty much mineageddon always being on the cards. They hint about a potential small number of fatalities.

It made me ask one question, which seemed a very sensible one to ask.

Why not drill into the workings below adit level and then retimber the adit?

The adit is next to the river. It is x-cut for about 30ft where it turns south along a crosscourse, which has run in. This intersects the lode shortly after. Below the adit portal is a wide track next to the river. There is plenty of space around to drill several holes into stoping below the river. This would intersect water at 7 bar pressure, which could clearly be controlled. It would be then possible, via the results of several holes to prove that the water pressure was negligable and then get on with clearing and restoring the adit.

Clearly, a huge expense and fuss was undertaken around this mine and my tiny mind cannot fathom why my suggested course of action was not considered. (read the conclusion again)

So, engineer types, why do you think this is the case?

.....looks like a fairly standard document of its type.

The problem for any document of this sort is that it is focussed to a large extent on liability avoidance or mitigation. It will pass over a long series of desks occupied by people who are primarily interested in doing nothing and spending nothing, but making sure that no liability is accrued in the process; ideally, that any liability accruing is clearly seen to belong elsewhere.

Unless there is an actual hole in the road, which has appeared overnight and shows every sign of getting worse quite quickly and whose ownership is fairly clear, it's extremely difficult to establish a case for actual intervention.

The most likely outcome for a water pressure event is that it will tend to mitigate itself over time. This means that substantiating the case for a course of action involving putting men into an adit after drilling into a large, unknown body of ( probably contaminated ) water at 7 bar or so, is pretty much impossible.

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It seems plain to me that they have just spent a lot of money on some very spangly concrete caps and the actual problems of "stuff on the move" have not been addressed at all.

7 bar water pressure is pretty serious though! If the men did encounter that in the adit, they wouldn't have been in there for very long!

.. you have answered your own question.

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