Hello, Element,

If the San Gold stope crews are breasting down with jacklegs in these shrink stopes, they would typically blast each round of holes drilled in an exposed breast as it was completed.  This would perhaps be seven to nine ft deep holes on perhaps a seven ft high breast.  At five ft width broken, this could be 280 cu ft broken in each shot - equal to 24 tons at your 11.5 cubes per ton factor.

They could be working on a rill to get extra faces, but this makes drawing the proper amount of swell muck tricky.  They could be drilling with stoper machines, which allow much more exposed stope back to be drilled and shot in one cycle.  However, the old buzzies aren't used much any more, because working under the stope back is considerably less safe than breasting down.

It's difficult without seeing the actual stopes to predict the rate of progress or estimate a close time for completing the stopes so as to pull them dry.  Hope this provides some food for thought.

Plumb Bob