Flooding occurs in virtually every mine, certainly in the San Gold watershed, through water seepage. It is constantly pumped out while the mine is active. Once a mine closes, it fills with water. Care and Maintenance (ongoing pumping) prevents this.
Decommissioned mines are allowed to fill, but the water which exits the mine needs to be treated according to environmental standards - that process can continue for decades or longer.
Old mines that are recommissioned must 1st be pumped. And yes, it is an expensive process.
Thanks for your comments Goldbugr - I'm still hoping for that long expected dramatic rise in the POG. Sandgold is not the only company teetering on the edge in this current price environment.