well then bridgh the tube and back fill
bridging a tube can f..k the dig up, its pointless as it just fills the tube with sh..t. And can cause the dig to collapse, happen round here not long ago. The quarry will soon dig back through the tube
i rather bridgd it mate known the quarry will get back out safely
what do you mean alan the quarry will get back out safely surely you dispatch your quarry and remove it then back fill