Ellog auger drilling: Three-in-one method for hydrogeological data collection

The Ellog auger drilling method is an integrated approach for hydrogeologic al data collection during auger drilling in unconsolidated sediments. The d rill stem is a continuous flight, hollow-stem auger with integrated electri cal and gamma logging tools. The geophysical logging is performed continuou sly while drilling. Data processing is carried out in the field, and record ed log features are displayed as drilling advances. A slotted section in th e stem, above the cutting head, allows anaerobic water and soil-gas samples to be taken at depth intervals of approximately 0.2 m. The logging, water, and gas sampling instrumentation in the drill stem is removable; therefore , when the drill stem is pulled back, piezometers can be installed through the hollow stem. Cores of sediments can subsequently be taken continuously using a technique in which the drill bit can be reinserted after each corin g. The Ellog auger drilling method provides detailed information on small-s cale changes in lithology, sediment chemistry, and water, as well as gas co mpositions in aquifer systems-data essential to hydrogeological studies.