That's some interesting info.
I have been poking around United Downs looking at various bits and bobs to go into and the Whiteworks section did sound interesting. Again, the methane levels are a concern. I'm aware of the ability to strip oxygen out of the air of sulphides. I'm curious if United Mines always had low oxygen levels.... From what I gather, the tip has no membrane so water with it's associated organic load percolates through the rock and then rots and releases methane. The methane is about 1/2 the density of air and rises. It would only get caught in upside-down u bends or blocked rises, just like the Wheal Maid Decline. I would expect decent oxygen levels down there unless there are aerobic bacteria digesting the organic load in the water.
Such a massive amount of methane is exceedingly dangerous and there are numerous pathways a initiation reaction could start. If that lot did "go off", you would be looking at some serious damage. My bet is that the methane concentration goes up as you walk UP the tunnel towards the portal. There would be a large section between LEL and HEL.
If it did go off.....I'm not sure what would happen but knowing the ferocity of a 9.4% methane air mix in a ballon, it's quite serious. I would say that there would be some pretty big "unblockings".
Not sounding like some sort of eco-worrier, I would suggest that it was in the interest of safety not to have large and potentially explosive buildups of gas underground. If it did fire, you could have parts of the industrial estate going down holes or flying shaft plugs.
I'm interested in edging towards the united workings and having a look, they are very interesting. I plan to go down coads shaft and have a look around, but I gather that is on the edge of the bad air.
Before I do any of this, I'll get a gas unit.
I personally think united downs dump should be responsible for seeing the workings are adequately ventilated.
Can't remember how far the Wheal Maid Decline went (there are rumours) but I gather some interesting minerals were found in Whiteworks, which I gather has some large stoping indeed. I assume the entrance shaft (whiteworks) is in matey's scrapyard....what was it originally called?
Changing the subject on to Portreath, I climbed up into those workings and they have to be seriously old, same sort of era as Metalwork at Porthtowan, just old mans scrapings. Early/Mid 19th cent? Have found no record. If you stand there and face the sea, about 10 o clock there is a stick out rock which has some man made holes in it. On which locals say was built as a bath for one of the Lady Bassett's looks suspiciously identical to early shaft formats. If you go out of the cave and around to the left, there is another shallow shaft style working. God knows why.
Be interested in any united info.... fascinating place....
The shaft (williams, of the top of my head) which has a bent Clywd cap over a big grid over some dodgy sleepers looks interesting... (In front and down the hill a bit from gwennap stamps) can anyone with a plan say whether there are any levels off it.
It would also be interesting to know if there was any methane issuing from the mouth of that shaft..... It's bloody deep.
Anyway, hope this adds to the interest, stu