Oakeley H floor has dewatered again and can therefore again be accessed from the bottom of the Ch 34 incline.

It's only the second time I've seen this, and the 3rd time I've heard of it happening. There's not a great deal of exploration possible on H floor, but it is nice to see an area that spends most of it's time underground.

Didn't take any photos this time, but here's one from the last time around.

[img]http://www.aditnow.co.uk/showimage?f=/community/Cwmorthin-Slate-Mine-07-05-2006-Image-012/[/img]

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Please! Cwmorthin has no floor H. It only had a small floor G accessed from the subsidiary incline now flooded in Ch 1 West Back vein.

Chamber 34 is an Oakeley incline and all the floors accessed from it are Oakeley floors.

Graham

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Sorry 😞

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This is slightly confusing, Simon talks of H floor in Oakeley and Graham says there is no H floor in Cwmorthin Have i missed the point ???

This is slightly confusing, Simon talks of H floor in Oakeley and Graham says there is no H floor in Cwmorthin Have i missed the point ???

I think I wasn't quite with it last night 🙂 I referred to Cwmorthin H floor instead of Oakeley H floor and a deviation as a rebelay...

After Graham pointed out I had incorrectly referred to Cwmorthin H floor, I edited the original post. Sorry about the confusion 😞

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Please! Cwmorthin has no floor H. It only had a small floor G accessed from the subsidiary incline now flooded in Ch 1 West Back vein.

Chamber 34 is an Oakeley incline and all the floors accessed from it are Oakeley floors.

Thinking about that, I can understand the logic, even though it's a bit difficult to get one's head around to start with!

Presumably the G floor workings which are accessed from the E-G incline in CH.1 West would also have been worked by Oakeley? There seems to be no F floor in between, which suggests that they were intended as a continuation of the 'Z' chambers, which drained down towards Oakeley, whereas the Cwm back vein drained the other way, thus 'squeezing' out F floor as the two floors converged.

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Yes the eventual intention was for the "Z" series of chambers on Oakeley G to reach the new Cwmorthin G, whereupon no pumping would be needed at Cwmorthin as all the drainage water could pass through Oakeley. As it was, water from the Back Vein Lwm had to be pumped along the E floor level to the point where it could be discharged down the roofing shaft into the G floor "Z" chambers. Similarly water from E floor Old Vein had to be pumped from the E floor Lwm up the slope into Oakeley DE, around the corner and then discharged down another roofing shaft into one of the Oakeley G floor exploratory levels about wall 41.

When I wandered round the place in the early '80's the pipes were still lying around, indeed I did suggest dewatering the Cwmorthin Old Vein by using a basic siphon along the old pipe route. Once the pipe had been filled and the discharge pipe lowered sufficiently down the shaft, it would have worked well!

Regarding F floor, it was always an odd floor, being only a "half-floor" part way between DE and G, and existed rather as a legacy from ancient days so it is not surprising that no provision was made for it. It should perhaps be understood that working in the far west of Oakeley had largely been abandoned in preference for deeper workings closer to the main inclines in the east.

Graham

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Yes the eventual intention was for the "Z" series of chambers on Oakeley G to reach the new Cwmorthin G, whereupon no pumping would be needed at Cwmorthin as all the drainage water could pass through Oakeley. As it was, water from the Back Vein Lwm had to be pumped along the E floor level to the point where it could be discharged down the roofing shaft into the G floor "Z" chambers. Similarly water from E floor Old Vein had to be pumped from the E floor Lwm up the slope into Oakeley DE, around the corner and then discharged down another roofing shaft into one of the Oakeley G floor exploratory levels about wall 41.

When I wandered round the place in the early '80's the pipes were still lying around, indeed I did suggest dewatering the Cwmorthin Old Vein by using a basic siphon along the old pipe route. Once the pipe had been filled and the discharge pipe lowered sufficiently down the shaft, it would have worked well!

Regarding F floor, it was always an odd floor, being only a "half-floor" part way between DE and G, and existed rather as a legacy from ancient days so it is not surprising that no provision was made for it. It should perhaps be understood that working in the far west of Oakeley had largely been abandoned in preference for deeper workings closer to the main inclines in the east.

Graham

There appears to be a change of vein from the Old (?) Vein in the "Z" chambers in wall 39 which switches to the (Cwmorthin) Back vein - presumably the "Z" designation was to distinguish the fact that these chambers were in a different vein, thus there's a chamber 38 and 39; and a Z38 and a Z39?

Going back to where we came in, it looks as if there were a couple of cross-levels connecting Floor H in the New Vein to Floor H in the Old Vein - I wonder if the New Vein chambers are still connected and if so whether they've drained at the same time?

Seeing as floor H seems to run for a long way (Ch 30?) in the New Vein, it might be worth seeing if we can somehow get down to it and have a look.

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Yes when you reach chamber 38 on G from the chamber 34 incline, you then turn right (north) along a long level that goes into the Back vein and accesses the Z series of chambers. The reason Z was used was that originally the Back Vein walls and chambers were identified by letters - but as there are only 26 letters in the alphabet they ran out! The subsequent walls and chambers were named Z1, Z2 etc. Since most of the upper back vein was inaccessible by the 1930's, they simply used the Z to indicate the Back Vein in conjunction with the normal chamber number. Z38 does line up with 38 Old Vein and 38 New Vein.

There is a run of New Vein chambers on H from 30 backwards, but most had H floor cut away by working on G and below. Chamber 22 is/was large, but beyond this there appears to be an undervein level on H going east which should be clear.

Hope this makes sense.

graham

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When I wandered round the place in the early '80's the pipes were still lying around, indeed I did suggest dewatering the Cwmorthin Old Vein by using a basic siphon along the old pipe route. Once the pipe had been filled and the discharge pipe lowered sufficiently down the shaft, it would have worked well!

The pipes are still there and I've seriously thought of doing the same, to the extent of bidding on a length of firemans hose on ebay recently to do the job but I got outbid. The existing piping is no good, too old.

It'll drain easy enough but soon fill up again, could do with a proper powered pump system installing but the Back Vein will be getting one of those first :thumbsup:

Yeah, well, I wasn't suggesting using the original piping even then! A good length of that flexible stuff they use for field drains these days would do.

And yes, you'd need a permanent solution by a pump, unless you wanted to stay by the siphon with a valve to stop it when the inlet end was down far enough so you could restart it again without having to fill it.

I have the feeling I slipped up on my last email regarding pumping - the back vein water was discharged into Lefal Ffrench - it only flowed down the roofing shaft when the pumping stopped and E floor flooded.

graham

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The pipes are still there and I've seriously thought of doing the same, to the extent of bidding on a length of firemans hose on ebay recently to do the job but I got outbid. The existing piping is no good, too old.

It'll drain easy enough but soon fill up again, could do with a proper powered pump system installing but the Back Vein will be getting one of those first :thumbsup:

A power supply being the main problem I'd expect!

In an odd way, some form of pelton wheel at the bottom of the chamber that the BVI drains down into could do the trick, making it self-powered - you'd only have to lift the water perhaps 3 or 4 feet, but it falls perhaps 20 feet at the end, so there should be enough energy there to provide the power, even allowing for a couple of energy losses of 25% or so through the generator and the pump.

Hmmm... I can't help thinking I'm trying to invent perpetual motion!

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Indeed mr vanoord. You will note the continual discharge of water all year round from the dam on B, and you will note that if this was piped all the way down to E there would be a nice head. you may also note that putting a pelton on this and having it discharge to the Zeds will allow a few KW of power to be generated, easily enough for a few float-valve pumps (one in each vein) and maybe a little bit of lighting.

Anyway, the first project is stopping the adit falling in.

Ah yes, that has a certain logic that I had overlooked ;)

It's a bit of shame that work did not get far enough along the Z chambers to connect to the foot of the Back Vein incline.

Given the presence of several other tunnels in the mine that go nowhere much, I'm a little surprised that they didn't drive a shaft along G floor to connect to the E-G incline which would also have removed the need to pump the lwm at the bottom of the BVI, presumably freeing up valuable power.

Anyway... back to floor H! Presumably the pumped water which has dropped the water level down to H is being discharged through Lefel Dwr on floor G?

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Ah yes, that has a certain logic that I had overlooked ;)

It's a bit of shame that work did not get far enough along the Z chambers to connect to the foot of the Back Vein incline.

Given the presence of several other tunnels in the mine that go nowhere much, I'm a little surprised that they didn't drive a shaft along G floor to connect to the E-G incline which would also have removed the need to pump the lwm at the bottom of the BVI, presumably freeing up valuable power.

Anyway... back to floor H! Presumably the pumped water which has dropped the water level down to H is being discharged through Lefel Dwr on floor G?

I'd have thought so yes.

Yes it's odd they never connected the Z's to cwm's E-G bit. Mind you the floor heights of Cwm's G and Oakeley's G are not the same, which I also find odd.

What we need is a really, really long drill bit.

Yes it's odd they never connected the Z's to cwm's E-G bit. Mind you the floor heights of Cwm's G and Oakeley's G are not the same, which I also find odd.

Yes, that one's a bit odd - the chambers at the bottom of the E-G incline are something like 30' below the chamber that the Back Vein currently drains into, so presumably Oakeley would have had to change the slope of the chambers to head down to meet the chambers off the E-G incline.

I wonder if they did that intentionally, or whether the aim was to work the Back Vein downwards from G once they had run it along the length of the mine?

If my memory serves me correctly, there are a few chambers on H to the west of the Chamber 34 incline, but those do not go far enough to start to connect into the Back Vein and the 'Z' chambers.

Incidentally, which vein are the chambers off the Chamber 34 incline in? Presumably it's the Old Vein, although I have seen references to the Clay Slant vein (?) somewhere on floors G/H.

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Hmmm... I've been looking at my tracing of the only plan that shows the Oakeley modifications to Cwmorthin, including the E-G incline. (The abandonment plans don't show this!) I thought the inscription on G is 90'6" below E, but it COULD be 30'6"... has anyone actually determined the depth of the shaft ? The length shown on the plan does support the greater depth, but I agree it seems odd.

If H was intended, then it would fit better, as H would have risen by at least 10' from chamber 38 westwards... However this would have required the development of a series of Z chambers on Oakeley H floor in the Back Vein to follow on below Oakeley G -never done.

I'll have to have another look at my transcripts of reports.

I'll post a plan for the area to clear up any confusion as well.

Graham

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Hmmm... I thought the inscription on G is 90'6" below E, but it COULD be 30'6"...

Blimey Graham, we had a team of divers on site this year ready to dive that expecting 90'6"!

30'? give me a snorkel then and I'll do it myself...

Looks like my tracing was right - the following is from my Cwmorthin chapter - there's a variation on it in "Cwmorthin" :
"By November 1934 work was going on on G floor in the Back Vein to drive the floor westward under Cwmorthin floor E, but for ventilation only. The new chamber 34 incline hauler was now complete and in work, "accelerating" the western workings in Oakeley. It was thought that the line of the Cwmorthin Back Vein incline might be reached in 9 to 10 years!

By the following July (1935) the final chamber "Z42" on the G floor Back Vein had roofed through into Cwmorthin floor E, giving essential ventilation to the long level. Dams were now being constructed in Cwmorthin to the east of the Back Vein incline to pond up the water from the shattered workings above and then divert it along the Lake level.

October 1936
Jones now claimed he was "justified in advising sinking of the Back Vein incline to G floor as about 130 feet to the east was chamber 44, which was being dealt with by the Oakeley inclines." Otherwise, it would take too long for Oakeley to reach the area, and rock could be got immediately.

It was intended to sink down from the chamber 1 west in the Back Vein down to the level of G, rather than continue the old incline.

Despite Jones' exclamatory hopes, by May 1937 the same tones reappeared, it was now "difficult" keeping the mill fully occupied pending the completion of the incline down to G. The clearing in the Back Vein had been abandoned. A sunken pump from Diffwys was placed at the foot of the Back Vein incline on E to deal with the water. It was intended to sink in chamber 1 west, work east and west, and roof up to the original Back Vein incline from below. In the event, this was not done, sinking of the chamber 1 incline was completed by October, 85 feet below E floor. A haulage set was erected in the chamber at the top, again using ex-Diffwys equipment, but as the motor and gearing was at floor level, shear legs were used to raise the haulage rope to sufficient height to clear the crimp."

Need a new diagram, to combine certain features of Old and New veins as F wanders about a bit/lot - will have to work on it.

Graham

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I am really looking forward to this book. Did you say it had developed into more than one volume Graham?