Conventional drilling uses augers to penetrate the soil. As the auger rotates, soil cuttings are conveyed to the surface via auger spirals. Sampling and installation tools are positioned inside the hollow augers. These auger’s large openings allow access to the bottom of the hole without withdrawing the auger string. The auger acts as a temporary casing during drilling to facilitate sampling sediment and water and installing monitoring wells.
Hollow-stem auger drilling is fast, especially in shallow applications in poorly lithified to unlithified sediments, though restricted to soft, unconsolidated material or weak weathered rock.