Hollow stem auger is one of the most effective and efficient drilling and soil sampling methods available. Auger drilling is effective in most Pacific Northwest settings where bedrock is deep. Auger can easily drill in glacial till, silt, clay and sandy soils but will not drill into consolidated rock. Think of the auger as a large diameter, hollow center screw that the drill rotates and pushes into the ground during rotation. Soil sampling is done by lowering split spoon samplers on drill rods through the open center part of the auger. Calibrated, automatic sampling hammers drive the sampler into the soil in front of the auger gathering both the physical soil and geotechnical data in the form of blow counts.
Augers come in a variety of diameters from 3” inside diameter (6” outside diameter) up to 10” inside diameter (15” outside diameter). Wells up to 8” in diameter may be set with this method. Depths up to 200’ in the right conditions may be reached.
Soil cuttings are continuously brought to by the rotating auger and either stockpiled or placed in a soil bin or drums. Holocene operates a variety of large and small truck mounted and track mounted auger rigs to meet both on road and off road site conditions.