They drill holes for geotechnical and hydrological studies are done to see what the conditions will be when they put the decline through that area. The look for things like the rock being competent, faults, fractures, shears, permeabilty, etc. You want to know if there is anything that might cause you problems (like having an open fault connected to a lake, or rock that may have to be screened and bolted to keep it from falling in the decline etc). The one thing they don't expect to find is mineralization. You usually drive your decline through barren rock specifically to avoid this 'problem' and then turn into the ore body to collect your sample. I think we will find this to be a surprise 'discovery' for all involved.
... Been There