RE:RE:RE:Leach Pad slope stabilization Sorry about the response delay. I lost a computer monitor. It’s a little late in the thread, but here’s a reply anyway.
The cable controlled drag idea was to help stop the inevitable escarpment collapse. It may be applicable to moving material to the side on the lower, now flatter because of the fallen material, areas later if someone wants to retrieve the ore material safely, but if Victoria is told that they have to stabilize that escarpment right now, that might be a method of doing it.
This would definitely be a slow process, with a lot of setups, but it probably wouldn’t need a large work crew or a big fleet of equipment to get going and maybe possible with equipment that’s readily available. It could be a way of re-sloping material that you don't really want to get near.
I don’t really see what the explosives idea will do. When they fire charges at snow faces, which the charge shell can penetrate, it’s my understanding that they do it because they already suspect, often through core tests, that the face has shear failure bands in it made from different types and layers of snow. A good blast vibration will break those bands and the whole snow face will fall down. This heap material should be fairly uniform and would a shell go very far into loose gravel anyway. The only weaker area might be at the liner interface, but with all that new sluffed material at the escarpment toe, explosives thrown at it wouldn’t likely do much if the vibration from the one part collapsing didn’t make the whole pile come down when the failure first happened. A good surface blast would likely make some of the escarpment face that was going to fall down anyway in the near future flake off, but I doubt that it’s going to change the pile slope profile much.
Now, implanting explosives into the pile to blow out the face would definitely change the profile if not make the whole pile move, but drilling a hole to put a charge in loose, gravelly sized rock that still remains a hole when the bit comes out is hard, and where are you going to find someone nuts enough to sit on the top surface of an unstable pile even with just an air-track to do it? Regulators would probably frown on that idea anyway.
If some of the theories about the pad being too saturated are right, this period of no solution being added may help reduce the liquid content, as long as the area avoids heavy rain, which might make the whole pile more stable as it drips out to wherever it’s going. That also assumes that the leach pile material didn’t have too high a fine content which, after that was flushed down through the layers, might have gummed up the fluid flow lower down in the pile thickness and caused pooling at the liner interface. Those pooling’s, if they happened, would now reduce much more slowly or even stay put as they’re not getting any more fluid to increase the pressure to blow out whatever goldie sludge is preventing the downhill flow. The operators might have noticed if they were getting overall diminished expected returns of the volume of solution that was being added, but where the downhill bottom flow was being obstructed might be hard to point too or even do anything about. There was something about a fines reducing project being proposed a while back, but I can’t remember if they carried through with it.