Production.7 Oct 2017 17:25
No idea of the density or anything else but a metre cubed is around 1.2 tons of soil.so take your pick.
As for depth a presumption is all that would be done is widen the access as in artisanal gold mining with safety added.
So it's rely on the RNS info., ?
At some point the yellow will be in use again I should imagine asap.,
I may be wrong .,