Subsurface investigations are conducted for a variety of purposes including site assessments, groundwater supply exploration, aquifer protection protection planning, and site remediation. Methods used include test drilling, geoprobing and hydroprobing, and exploration geophysics.

Investigations conducted as a part of environmental or remedial projects generally involve a delineation of the extent of soil and/or groundwater contamination. Monitoring wells (or micro wells) are usually installed to facilitate measurement of water-level, gauging for groundwater supply exploration involves characterization of an aquifer relative to groundwater storage and transmission, water quality, and long-term safe yield. Investigative techniques involve test drilling and installation of wells or microwells, exploration geophysics, water quality analyses, and test pumping. 

The drawing above depicts a test boring rig drilling into water-saturated and unsaturated soils. A proper selection of drilling tools would also permit penetration and sampling of the underlying bedrock.