A big thanks to Miles Moulding for his OK to reproduce his recent email below.
Miles gives a very confident, convincing and detailed explanation of the original purpose of the Torwood Blue Water Pool.
Flooded downcast shaft – the water level in this shaft is considerably higher than that in the upcast shaft so there is no longer any connection between them.
My name is Miles Moulding and I work underground in disused mines (mostly as a consultant and or guide) and I’ve been a mining enthusiast for many years.
I can say with certainty what your blue pool is, I recognised it instantly.
Yes, it’s a colliery airshaft. It’s a special dog-leg type, typically used where the shaft comes to surface well away from the main working surface site in an area that is not secured and/or remote.
What you do is you have the main shaft (vertical, almost certainly) come up directly from the mine to extremely near the surface, typically just a few yards short.
You then dig a very short shaft just to the side of the main one, from the surface to maybe 4 yards or 6 yards deep. The two get connected with a tunnel.
Why do it this way? Because the miners didn’t want rocks and rubbish thrown down the air shaft into the mine from kids messing about at the top of the shaft. That’s why it’s offset, or “dog-legged”.
Quite a few here in Wales done the same way. Only used for vent shafts, not haulage shafts or similar, as the dog-leg poses no problem for air flow.
No need to do it that way on the mine site, as the site will have security. But in the woods in the middle of nowhere, a vent shaft would likely be done that way, it’s not a huge amount of extra effort and it means if people hurl things down it collects in the small shaft/chamber and doesn’t rattle down to the mine and pose a risk to men/machines below.
Railway tunnel vent shafts (or piston relief shafts) where the shaft is directly above the rails, will almost always be dog-legged in exactly the same way for the same reason. Right at the top.
The top of the shaft though should have a circular wall around it maybe 7 feet high. The bricks have probably been stolen or the wall has been vandalised and pushed into the pool. The shaft shouldn’t be open like that, you should just see what looks like a short stumpy chimney to stop people falling in (or driving cars down!).
The fact that it’s a mile from the mine’s main shafts is neither here nor there, that’s nothing for a Victorian colliery. It could have over 100 miles of tunnel belonging to it, emanating out up to 30 miles from the main shafts in some cases.
What’s Next ?
My next job is to get some decent quality video inside the second arch and see the first few feet of the vertical shaft dropping down over 800 feet — makes me shudder to think what might have disappeared down there already.
For the time being at least, I have to say that NOBODY SHOULD SWIM in the Torwood Blue Water Pool.