Eric, If they have a backfill operation going on the rock going down can weight more than the rock and voids coming up, and make it even better.
When the Davidson was dewatered in 1985(flooded since 1924) all the underground wood was found to be quite sound. Once the few ppm of O2 is gone they are quite anaerobic, and water does hot hurt the wood in the trees.
Some rails were bright and shiny(the old operation was tracked), but got a red patina of rust within a few minutes of exposure to the air. The deeps also absorb all the free O2 from the air. One long tunnel, with 20" of cold water in it was an education. A crew went way along it, and then struck a match as they had been told to do. What a dim stunted flame, but at least it burned, they walked back out ASAP.
No methane there, or other combustible gasses, never found in that type of mine, unless you intersect some graphite I suppose, and then the risk is there that there may be some in that seam.
It is all still down there, a trackless shaft 2500 feet long winding down by all the old tracked levels. You could park a tractor trailer down there. When it was closed they stripped everything off the site and sold it for peanuts as scrap, headframe, motors, pre-fab buildings, undergrund wiring, venting etc, etc. But that was before my time, as I would not have allowed it.
We have been told we could re-open it for about $2M, mainly for surface equipments, underground wiring, venting, and safing the walls and ceilings. At that point we would have some 500,000 tons around .25 Oz/ton. I think if gold goes above $400 it would be economic to do it.
Maybe next year???
Bill |
