Its a tough one, dewatering an underground mine with water...

Its a tough one, dewatering an underground mine with water issues. If its viable, companies will put in dewatering shafts (production bores) around the mine, to lower the water table and reduce flows in the underground mine. In this case it seems as though this fault/high flow zone was unknown until they hit it, and that they were mining and pumping with pump stations as they went deeper.

Without knowledge of the thickness of the area, the flow rates or the depth (if its confined and pressurised), its hard to say yes it will work or no it wont. A number of proposed underground mines in high rainfall areas of the tropics (indo, PNG etc) have not got past feasibility stage due to these water issues. They will most likely grout it up and try plug it to stop the flow. Staged pumping systems will work to dewater, but need the sump area to store water, and the bigger the flow, the bigger and more expensive the pump (and electrical costs) will be.

Previous mines I have worked at have been Open Cast mining (profitably) with 3 g/tonne gold, underground seams of 12 g/tonne were considered quite rich. So if its as you say, 45 g/tonne is very good and I imagine they will be doing all they can to sort out the water issues. But its a balance of safety/risk/cost benefit and we can only speculate unless we saw some internal reports.