Hollow Stem Auger Drilling
A method often used for site investigation, environmental and geotechnical drilling, and sampling. The hole is advanced by turning sections of flighted auger casing into the subsurface formations. Rotating of the auger flights carries the soil to the surface where samples can be easily taken.
For accurate location of samples, the auger pilot bit can be removed, and split spoon sampling can be performed through the inside of the augers at any depth required. This method is most effective when used in stable soil conditions which are generally free from building rubble, cobbles, and boulders.
Advantages of Hollow Stem Auger Drilling
- With this method the hole is drilled and simultaneously cased
- Hole can be advanced without the introduction of drill fluids
Disadvantages of Hollow Stem Auger Drilling
- Method is generally only used up to nine meters
- Hollow stem augers cannot drill through hard rock or boulders