Holostem Auger

    Hollow stem auger drilling utilizes 5-foot auger sections with bolted connections and typically have inside diameters of 2- 1/4 to 12- 1/4 inches.  The drive cap assembly attaches to the top auger connection and transfers rotary power and axial force from the drill rig through the auger and to the drill bit.  
   
   Cuttings from the auger advancement are returned to the surface clearing the bore hole and allowing further advancement.  Always check to see that the rod string and sampler is at the bottom of the auger and proper sampling depth. This drilling method is particularly useful as the auger acts as a temporary casing to prevent caving of weak soils or flowing sands as well for the installation of various types of specialized instrumentation.  

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    In most cases the torque of the drill rig, dependent on the formation type, will determine the depth the bore hole can be advanced.  Typically, this method of drilling will advance to no more than 100 feet.  Continuous sample tube systems and standard penetrating systems are also available for use with this method.  The use of other auxiliary equipment is necessary during sampling with this method and typically is not as time efficient as air rotary.