Must be able to run a skid steer, backhoe, excavator etc. Really good job.

Weird question.An excavator that dids by hand.You know even grave diggers use axcavators.Sorry I don’t really understand your point

Farmboy is right a foot should be enough. Another suggestion is to tar or plastic the wall itself as long as you have it exposed. It will only help in the future and isnt that expensive. Good Luck