open pit mine in full operation, with machinery extracting minerals

bedrock benches building materials commercial value dimension stone downward ramps earth extraction ecological impact excavator excavators flow paths garzweiler surface groundwater levels hydraulic shovels hydrology industrial sector kittilacurren gold lignite megamining mineral deposits types minersa health mining angles equipment industry process safety techniques opencast openpit ore body overburden pit bottom size pollutants quarry ramp system rock blasting excavation falls precautions soil sunrise dam vegetation underground veins waste