Hollow stem augers

The hollow stem auger column rotates as it drills into the ground and is constructed to push soil up and out of the borehole along the outside of the auger. The auger itself is driven by a mechanical drilling rig. A plug is placed through the auger to protect soil from rising through the hollow portion of the stem. Samples are obtained by retracting the plug and lowering the sample collection tube through the auger. Casings and screens for access holes can be placed in the hollow stem to prevent the borehole wall from collapsing and to ensure discrete interval samples. Casings tubes may be also used to isolate near-surface contamination while drilling continues with a smaller diameter auger.