To go through this in full would be a bit lengthy in a forum, even for me! I'll post a document shortly - and you can then read it through at your leisure. Suffice it to say there are NO connections between Oakeley and Cwmorthin in the Back vein apart from on DE and G - why? - because there are NO Oakeley Back Vein workings that far west! The G Back Vein was an isolated section, which was why it was accessed by a long North going level.
Just to complete the story of the dewatering, however:
"[i]In 1932-33 in the west the dewatering level for the Back Vein was not proceeding at the hoped for rate. A 5.5 inch hole was being driven ahead of the level, the whole being done by Messrs. Isler - a French firm after whom the level was eventually named - Lefel Ffrench - or should that be Lefel Ffrainc ? Anyway, the rock proved harder than expected, and the effects on the bit were to break and wear some of the diamonds and their setting. The bit was replaced by one made of "Stellite", but this drastically reduced the drilling speed to 12" per day. The Oakeley engineers, however, were optimistic that they could easily modify the whole arrangement, and were hoping for 20" per day as a result. Fifty feet remained to be driven by February 1933, of which 27 feet had been drilled. A trial level on Cwmorthin Old Vein floor D disposed of the hope of finding any economic New Vein beneath Cwmorthin - the future had to lie in the Back and Old Veins.
The bore hole penetrated through to the Back Vein of Cwmorthin on the 21st. April, 1933, and the draining down of the estimated 45 million gallons contained in the Back Vein workings was completed to bore hole level in 4 weeks. The cost had been £393/8/6d. plus the costs borne by the Oakeley Company for tool setting, compressed air, mechanical assistance and lighting. The level was subsequently driven through along the line of the bore hole, and the residual waters pumped out. Preparations were now completed fro laying track suitable for a petrol loco along the DE level to serve the chamber 34 incline, as it was thought too long for horses.
The dewatered Back Vein of Cwmorthin was now examined. Most was "inaccessible and dangerous", the roofs from D upwards having collapsed in several places. The chambers to the west of the old incline were good however. If for no other reason, the dewatering was a good job, thought Humphreys, "as the water will no longer be a menace." By March, 1934, a test level had been driven in chamber 4 west of the old Cwmorthin incline, which proved the Back Vein to be about 160 feet thick, and "gives bright promise for future development of this Vein on Oakeley floors below Cwmorthin." The chamber 34 incline was now being properly equipped with an electric motor and two drums. The power cables were fixed in position by September and the whole thing was ready for testing. However, the shortage of compressed air at these extreme extensions of both the Oakeley air network, and that being supplied by the compressors at Cwmorthin was considerable, and both Humphreys and Percy Jones were certain that what was needed was a new compressor situated close to the chamber 34 incline would suit both, especially as the cables were already there."
That should keep you thinking for a bit. Most of this has appeared in "Cwmorthin" though the wording may vary a bit.
Graham
The map is the territory - especially in chain scale.