Monitoring wells are used to obtain ground water samples and water level elevations in aquifers. They also can be used to estimate the hydraulic characteristics of aquifers. The wells are constructed by advancing a boring with a drilling rig, installing a well casing and screen, and backfilling the annulus between the casing and the wall of the borehole.
While a borehole is being drilled, soil and rock samples should be collected at frequent depth intervals. Careful observations of drill cuttings can guide the collection of undisturbed samples. Soil and rock samples are used to define the stratigraphy of a study area. In environmental investigations, these samples can be chemically analyzed to determine the extent of subsurface contamination. All cuttings and samples obtained during drilling should be carefully described in a field logbook.