Question - The chances of collapse

[DaveFM]

No. I meant that carbon dioxide can be detected because low levels make you breathe more deeply, higher levels give a choking sensation.

Carbon dioxide is denser than air, so you'd expect to find it in the low spots in a cave or tunnel. This is one reason for carrying a gas detector on your belt, or a Davy lamp in your hand; the detection system encounters the gas whilst your head is still up and out of the way. If you encounter a pocket like this, don't bend down!

You're only really likely to hit carbon dioxide in either coal mines (in which case either you know the safety drill or you're an idiot) or if some twerp has lit a fire in the tunnel system previously. Carbon dioxide isn't as dangerous as carbon monoxide which is poisonous in low concentrations, nor is it as nasty as hydrogen sulphide.

Just take a known-working gas detector if you're going into anywhere except caves or stone mines.

I read last year of a fatal accident where an explorer abseiled into a mine shaft, hit bad air and suffocated before he could get out. I also read that atmospheric air pressure affects gas in a mine, if air pressures are low this can cause bad air/gases to be pushed nearer to entrances.

 

[novice_strength]

No. I meant that carbon dioxide can be detected because low levels make you breathe more deeply, higher levels give a choking sensation.

Carbon dioxide is denser than air, so you'd expect to find it in the low spots in a cave or tunnel. This is one reason for carrying a gas detector on your belt, or a Davy lamp in your hand; the detection system encounters the gas whilst your head is still up and out of the way. If you encounter a pocket like this, don't bend down!

You're only really likely to hit carbon dioxide in either coal mines (in which case either you know the safety drill or you're an idiot) or if some twerp has lit a fire in the tunnel system previously. Carbon dioxide isn't as dangerous as carbon monoxide which is poisonous in low concentrations, nor is it as nasty as hydrogen sulphide.

Just take a known-working gas detector if you're going into anywhere except caves or stone mines.

Right now I'm only going in limestone or sandstone mines (only mines close to where I live) which still has terrible breathing conditions. I took photos in the blebo mines and only 2 wasn't obscured by dust *cough cough cough*

 

[Dan1701]

I read last year of a fatal accident where an explorer abseiled into a mine shaft, hit bad air and suffocated before he could get out. I also read that atmospheric air pressure affects gas in a mine, if air pressures are low this can cause bad air/gases to be pushed nearer to entrances.

You have to learn the difference between danger that's fun, and danger that should just be avoided. Mines with dangerous gasses in them are not fun, they're just stuff you need to know about to avoid. Similarly going into sewers during a thunderstorm is just daft, ditto moving stuff about in "death onna stick" unstable quarries.

Dangerous places are what drones and remotely operated vehicles are for; they are also quite useful when the local security are annoyingly vigilant clowns...

 

[DaveFM]

Right now I'm only going in limestone or sandstone mines (only mines close to where I live) which still has terrible breathing conditions. I took photos in the blebo mines and only 2 wasn't obscured by dust *cough cough cough*

Your 'dust' in pictures might well be vapour from your breath, because mines tend to have such humid air breathing out can cause misting, I've had this happen to pictures of mine, easily avoided by using the timer and stepping back, or avoid breathing out through your mouth when taking pictures. Also watch out for condensation on camera lenses.

 

[novice_strength]

I didn't

Your 'dust' in pictures might well be vapour from your breath, because mines tend to have such humid air breathing out can cause misting, I've had this happen to pictures of mine, easily avoided by using the timer and stepping back, or avoid breathing out through your mouth when taking pictures. Also watch out for condensation on camera lenses.

It was definitely dust. I was using my GoPro session so I didn't realise how bad the photos were till I got home. Wish those mines were a lot bigger, there is 2 small tunnels going somewhere or nowhere but no way I'm crawling through them to find out

 

[wormster]

"Just take a known-working gas detector if you're going into anywhere except caves or stone mines."

Plenty of caves and associated digs on Mendip (and elsewhere) can suffer from varying levels of Carbon Dioxide, (along with other pollutants depending when the dig was last blown up), so if you're unsure take a quadgas detector everywhere underground, fusk it why not carry a dosimeter to see just how many rads of radon you get per trip!!!

 

[Hmp-Caver]

Thought I'd share my two cents: Basically things to look out for in terms of collapse signs whether recent or imminent depends mostly on a few contributing factors, being Weather and time deterioration (One section ten years ago might have been solid and sound but today could be completely caved in) any kind of disturbance of the earth, whether construction or works above ground disturbing the layers of any fault lines below if any, and the other one being rotten timber caused by acidic and often stagnant water (usually has a reddish hue and is quite dangerous and irritant). Other things to be mindful of is any uneven flooring, if theres any fresh looking pieces of rock/slate/spoil on the ground that looks like it fits with the roof anywhere, creaking in the wood, it all varies but as with any Mine (and even caves) if in doubt, stay the feck out!

 

[RichardB]

Right now I'm only going in limestone or sandstone mines (only mines close to where I live) which still has terrible breathing conditions. I took photos in the blebo mines and only 2 wasn't obscured by dust *cough cough cough*

Blebo Craigs Quarry is the most unstable underground space I've been in. The other Blebo quarries are fine (subject to your own assessment on the day of course) but I would advise against going into Blebo Craigs. There is a lot of very big stuff on the floor that I can remember being in the roof. I think it's also the only one where the workers felt the need to add supports, so it must have always been dodgy.

 

[Dan1701]

Another one to listen for in any mine with wooden props is a repetitive knocking sound. This indicates the slow failure of a pine pit prop. In times past in Cornish mines especially, the sound was considered supernatural, the results of small supernatural gnome-like creatures called Knockers, which made the sound in warning of imminent collapse. The supernatural aspect probably doesn't exist, but the knocking sounds are real and are a very useful warning of impending doom.

 

[wormster]

Same in Bathstone mines if the little "tell tail" wedges in the ceiling start shifting and falling - RETREAT!!!

 

[Dan1701]

Same in Bathstone mines if the little "tell tail" wedges in the ceiling start shifting and falling - RETREAT!!!

Aha, tell-tale wedges are something I hadn't heard of before. Clearly if the workforce felt the need to hammer such warning devices into the cracks in the mine roof then movement was an expected hazard and common enough for a warning to be required.

Whenever you look at exploring a mine, look at the safety systems the original miners used, and try to mimic them. Canaries and Garforth lamps meant that flammable, explosive and choking gasses were expected, tell-tale wedges mean movement is expected, and so on. Ironstone in a mine is another one to beware of, since it tends to pull oxygen out of the air and people aren't good at detecting low oxygen without outside help.

One other thing to be wary of here: whilst methane, carbon monoxide and hydrogen sulphide detectors last quite well, oxygen electrodes need regular servicing so if your 4-gas detects low oxygen, keep it serviced or otherwise carry a Garforth relighter lamp and make sure you know how the flame behaves in low oxygen conditions.

 

[BullyMong]

My advice to you would be just use a bit of common sense, if its looks rough give it a miss

 

[DaveFM]

Same in Bathstone mines if the little "tell tail" wedges in the ceiling start shifting and falling - RETREAT!!!

Same in Bathstone mines if the little "tell tail" wedges in the ceiling start shifting and falling - RETREAT!!!

Is that what those wedges are for? I always thought they were just a crude measure to stabilise the roof whilst mining was taking place, didn't realise they were meant to fall out as an indicator of unstable roof rock.