Ann: Standout 43Mt Maiden Cu-Co Resource at Emmie Bluff, page-9

Yes there is a long memory of the GBG issues.
As noted on another post, the extraction of the minerals 900m below ground level will require expert mining skills.
Also due to the thickness of the minerals being up to 100m thick, one wil have to construct some monster structure to support the 900m of rock above.
Maybe some sort of prestressed postensioned support beam/slab system to extract the minerals.
Until that is solved it is but a pipe-dream.
Hopefully there is some really good structural engineer with the experience of supporting 900m of rock. In 50+ years in industry I haven't coime across one yet, Hopefully COD have some contacts.