Terra Drill Inc. offers many options when it comes to hollow stem auger drilling. We have every size of hollow stem auger from 3-1/4” inside diameter (I.D.) to 12-1/4” I.D. augers. This wide range allows Terra Drill to sample soil and install monitoring wells throughout a wide range of applications, including monitoring wells, permanent casings, recovery wells and pumping wells.
Hollow stem augers are used in most soil and overburden conditions routinely encountered in the field and allow the installation of the various types of wells in a cased bore hole environment.
Routinely the hollow stem auger is drilled into the ground with a center plug attached to the drill rod that rides at the bottom of the borehole. The center plug is used to prevent the soil that is being drilled from entering the inside of the auger. At the desired interval the center plug is removed from the inside of the auger and the sampling device (Split Spoon, Shelby Tube or core barrel) is lowered into the hole and the sample is taken. After the sample is taken, the center plug is attached to the drill rod, lowered into the auger and drilling resumes. The process continues until the desired depth is reached in the borehole. Depending on auger size, type of geological conditions encountered and drill rig used, this method can be used to efficiently collect subsurface data to depths of over 100 feet.
Once the required depth has been reached if desired a well or other instrument may be installed through the inside of the augers. The auger will then be pulled from the borehole and sand pack or other materials may be installed leaving the well or instrument in place. This can be completed in a controlled environment without the risk of the borehole collapsing during installation.
