There is an old trick involving a suitably sized plastic drinks bottle with the bottom cut out (but keep the screw cap 😉 ), 3' of hose pipe, 1L of Sika 4A Waterstop, half a bag of cement and a bit of luck. Involves getting wet but should have it stopped in an hour.
If considering anything like a stopper or bung then please never underestimate the pressure of water that can build up in there.....keep those pinkies clear!

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If considering anything like a stopper or bung then please never underestimate the pressure of water that can build up in there.....keep those pinkies clear!

Anyone got a rough idea of the head involved as the pressure will 0.433 PSI per foot head.

Given that the hole is at least a couple of hundred metres long, cuts water at an indeterminate height and is going through fractured rock, a bung is at best going to make the water come out all over the place and at worst (water coming in from the surface) is going to have a dangerously high pressure (for 200m about 20bar or 285psi) which would result in a force of ~9kN on a 3" bung. That could seriously hurt...

As the rock is fractured, a bung may just cause it to collapse so the hole needs to be filled as far up as possible with something that will seal as many of the cracks around as possible. Not practical to get a cement pump in but expanding foam might just work...

Or we could just pipe it down to the horse level.

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There is an interesting report (on here somewhere) regarding Old Gunnislake Mine and the resulting chaos caused by widely fluctuating water levels. I think the adit has about 7 bar behind it, which is enough to cause water to squirt out of the rock face under considerable pressure and the report talks of a rock burst being a possible scenario.

When you consider the amount of flooded stoping above this level and the volume of water it contains, the thought of the blockage clearing itself is quite mind blowing. If this were to happen, I wonder if there would be some special effects style phenomena on the surface.

I always wondered why there was not an attempt to cut the workings with a 5" bit, then either recommission the adit, or drill some significantly larger holes to permanently drain the workings. (given the houses above and the possibility of subsidence/etc). Either way, 7 bar is pretty gnarly and in a borehole situation with a wooden stopper, could fire it out like a cannon and probably discharge a surprising amount of water in a very short time!

Interesting contributions!

maybe the solution is not to try to stop the water but to divert it elsewhere and out of harms way.

If a bung with a hole were made, it might be possible to attach some alkathene water pipe and duct it away.

I would need to know the estimated flow rate and the nearest available sump which would be suitable for disposal.

This might sound a bit pie-in-the-sky, but lately we've had some pretty good brainstorm ideas leading to positive results. (Grove Rake syphon for one..)

Maybe if anyone (Helen?) could PM me with exact location of the offending 'ole we could go have a look-see and think about options.

br MARK

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If a bung with a hole were made, it might be possible to attach some alkathene water pipe and duct it away.

That's the trick with the drinks bottle and the rapid-set. You then either pipe it away by hose pipe.....or you just screw the cap back on the bottle. ;)

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There are no sumps that are open in the area that could take the drained water, but a few blocked ones. It would be interesting to see what the rate of water will be in a few months time.

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Is it worth directing it down the continuation of the borehole, see if that drains somewhere? If it does, then a short length of tube/duct/pipe is all that is needed.

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Presumably this water comes out stopes in the higher strata, anything from the Firestone down.
Once the initial flow subsides, it presumably could be piped down to the horse level, where it is now ending up anyway.
Since the water level around the county boundary never seems to vary much, it is probable, that a lot of it makes it's way, down to Nentforce level.