Negligible surface impacts, after rehabilitation of course
My specialty is surface subsidence, its prediction and optimisation of mine design to minimise surface impacts. Properly designed crown pillars in a metal mine will result in zero surface subsidence. Of course there is all the surface infrastructure, tailings dams, waste stockpiles, the prep plant etc etc, but at the end of the operation, thats all dismantled and the area rehabilitated over the next 10 or 20 years. I'm sure you know more about that than me, as I remember reading you were an enviro.