Percussive Drilling made use of by using a driving stage/drill at an all-time very low in the long-lasting casing is outlined as displacement strategy Whilst once the air is utilized like a flushing medium. It's outlined being a non-displacement technique. pile - prepare in stacks; "heap firewood around the fireplace"; https://byd-atto-3-extended-range48158.dbblog.net/8644313/pile-secrets