To try and dig into a cave below my house?

[TimeToChangeNameAgain]

There’s a small network of caves in my town which were open as showcaves until the 80’s but then all shut off. The dad of my dc’s best friend is a keen caver type person and showed my dh a map of these caves which appear to go directly under our garden.

The pair of them plus 4 kids have been in the garden all weekend and managed to dig what looks like a grave. At the moment I’m leaving them to it because I’m assuming they’ll lose interest soon and they’re not actually going to find this bloody cave. The dc’s are so excited about it - convinced that they’re going to have it as the best den ever and find loads of fossils.

They won’t actually suddenly fall into a cave will they? The stuff I can find about the original caves says that they’re granite and limestone - they’re just digging through earth and a few stones at the moment. I’m assuming they would have to actually chisel away loads of rock before they hit a cave but I’m completely clueless. I really don’t care about them digging a hole in the garden but I don’t want them to actually find anything.

Would you try to stop them? Or just leave them digging? They won’t start up again until next weekend and I’m hoping they’ll have lost interest by then and I can turn their grave into a little pond.

If the ground collapses around them, would be able to dig them out before they suffocate?

You also have to be careful of bacteria in soil.

The caves were shut as the only entrance was right next to someone’s front door. I guess it wasn’t making money so they shut them. Now the house is a holiday home and the door is all fenced over.

My bil is an engineer and they have been consulting with him about the safety of it. They’ve propped the sides of the hole up with various planks and it looks fairly secure. It’s also only about 4 foot deep at the moment.

Dh and his mate have started lots of projects over the years. None of them get finished, there’s an old tug boat in the garage that’s been in pieces for several years that they were going to restore and take the dc’s fishing on. It’s not been touched in years.

I’m assuming the grave that has appeared in the garden will be left to fill up with rain. There’s no way they could get any kind of machinery in the garden so they won’t be able to go through rock (which I’m guessing they’ll have to do before a cave hole appears?).

Like I say the map of the caves do show they’re under our garden but our house is a lot higher than the entrance. I’m assuming caves are more likely to go downwards (?), even if they just go along straight we’re a good 15-20 metres higher than the house with the entrance. I’m not in any way concerned that they will actually get into the caves.

There are quite a few caves scattered around the area that they love exploring. I don’t generally go but on the few times I have we’ve always done it safely. I don’t let them go in any caves that get full at high tide (I find the thought of them being trapped with the tide coming in just horrifying) and they never go anywhere that the largest adult can’t fit through comfortably.

Kitley show caves?

mashed I didn’t know there was bad bacteria in soil. Off to google and find something else to worry about. I’m not keen on them digging much deeper but I’m hoping they’ll have lost interest by next weekend. If they haven’t lost interest having some facts about soil bacteria in my arsenal would be good.

yetanother no, not far from there though. Same stretch of coastline.

Could be your 10 minutes of fame OP, you'll be on the news later as a massive sink hole opens in your garden.

I’m assuming caves are more likely to go downwards If they're natural caves, depends on the strata of the limestone, whether horizontal or dipping. If man-made, who knows?

Some of the young cavers currently exploring got the bug through joining their parents on digs - depends really on what sort of a caver the "dad of my dcs best friend" is, eg whether he's a sport caver or a digger.

They do have a rescue team in the UK, They have several! Cave Rescue Organisation, Upper Wharfedale Fell Rescue Association, Derbyshire Cave Resecue Organistion - and that's just covering one area.

they won’t be able to go through rock (which I’m guessing they’ll have to do before a cave hole appears?). If it's a natural cave system it could have an inlet that could be enlarged to take a person. If that was the case, you'd expect there to have been a lot of discussion beforehand as to exactly where to dig as they'd be trying to locate the inlet, rather than simply dig on the line of the passage and hope to hit the roof.

This sounds bonkers..

And I say that as the child of two experienced cavers (one a fairly well known name though some years back as he's long retired now), who has been on digs, been the handily sized child posted through small holes etc etc.

You'd need to have the most up to date surveys of the cave system, and be sure there was some natural opening - blasting holes into systems that already HAVE an entrance is a really major operation and if its going to damage features inside the cave, a pretty big no-no!

I think this is the best thread I have ever read on mumsnet!! Your concern is palpable!

Good luck to them digging 20m downwards! Honestly, how daft are they?

TeaForTara There are cave digs that have gone down a lot further than that

Any chance of a photo of the hole?

I'm assuming that the grave that has appeared in the garden will be left to fill up with rain

And then they will need a plan to pump it out unless they are happy with a hole several feet deep full of water. How safe is that with DC around!

Any chance of a photo of the hole?

This

I'm starting to feel suffocated just at the thought of these caves. I did it once on one of them "outward bound" thingies.

Never knew I was claustrophobic until that point.

I can't stop reading though! :)

Can't actually believe anyone would be as foolish as to let their kids go digging an unsupported hole. It's not gonna end well.

It's not unsupported. OP has described the timber supporting the sides.
(Whether the support is adequate only those on the ground will know).

I'd put a stop to it now. Digging a hole is affectively creating what is called a 'confined space'. I'm a structural engineer, and aside from the obvious risk of the hole collapsing on them, the massive unseen risk is gases which settle in holes like this. They can be odourless, tasteless, invisible and you can very quickly lose consciousness. It doesn't have to be deep...it's simply that these gases can be heavier than oxygen so they sink and you end up with a hole with little to no oxygen in it.
There's also an obvious risk of soil falling in on them. The stability of the soil depends on the soil makeup. They could be buried and suffocated.

When I was a child, I started digging a huge hole and was very sad when my dad put an end to it for the same safety reasons as I now mention and appreciate as an adult. It sounds scaremongering but any excavation, even a small one, can be extremely dangerous. There's a reason that construction is one of the most dangerous industries and why we have to do confined space training etc.

I’ll take a photo of it tomorrow when it’s light. I don’t know how serious Dh and friend actually are - the spot they chose to dig in the garden was based entirely on it being pretty much the only spot that wasn’t near a pipe, wall, house or my veg patch. The pictures I’ve found of the cave when it was open show it as being maybe 1-2 metres wide. Even if they were digging on the exact spot, the caves happened to go uphill rather than straight along or downwards, they don’t know if there are any inlets so I don’t think they’re suddenly going to just fall into these caves.

From what I can find out the caves were discovered when someone was digging out an area to build some house on. It was then excavated and they found lots of bones and then it was open to the public. It’s listed as an Ancient Monument so they’d better not actually get in there or they would be in trouble. Bloody idiots.

It’s true what the respondent above is saying about bad air, not to mention the possibility of methane buildup. It’d just be like someone to break through into the cave and then light a fag to celebrate.

That said, this whole thing is bloody hilarious and I hope OP keeps us posted. I once had to pot hole down a tiny culvert under our house to clear some wood that had washed down and was causing flooding in neighbouring properties. When I say tiny I mean so small there was only enough room for a small man (me) to wriggle down and have about 6 inches of room to move my arm with a saw. I had the foresight to tie a rope to my feet and have DW on the other end with strict instructions to drag me out if anything went wrong, even if it meant breaking my legs. Like the fucking genius I am I had the bright idea of taking the chainsaw down there, which worked brilliantly up to the point I started it and the very confined space immediately filled with fumes. What a twat.

Invite them into the house for hot chocolate and biscuits after their exertions. Stick a DVD on for them. Solved

I bet our dads knew each other @WiddlinDiddlin :D so cool!

If you've going to turn the hole into a wildlife pound then go have a Google about how deep to dig, creating different levels around the side, etc. It's really important the sides don't just go straight down otherwise you'll have a whole load of wildlife who'll get in and not be able to climb out again!!

I totally sympathise with you and the situation, OP even if I do also find it hysterical!

Pond, sorry! Silly autocorrect!

Bonkers. If they are that keen can they not find out how to get through the original door you mentioned?! Or failing that send them up the road to Torquay!