I might've been a bit hyperbolic in my hand wavey explanation. I'll clarify by stating I understand the costs associated with open pit mining are by no means negligible, however they are far less than those aasociated with underground mines. I still stand by the fact that I personally think that given the current climate they will need to find extra money, or come to some form of agreement with the contractors, in order to fulfill their upfront costs.
Now on the open pit to 50m remark, it is of my opinion that they are attempting to achieve a similar outcome to Mt Freda, where the easy to get and move ore close to surface is open pitted, then underground mining commences below said pit and the high grade shoots are followed by decline mining.
(20min delay)