is the generalized term for any narrow shaft bored
in the ground, either vertically or horizontally. A borehole may be constructed for many different purposes, including the extraction of water or other liquid (such as petroleum
) or gases (such as natural gas
), as part of a geotechnical investigation
, environmental site assessment, mineral exploration
, temperature measurement or as a pilot hole for installing piers or underground utilities.
and environmental consultants
use the term to collectively describe all of the various types of holes drilled as part of a geotechnical investigation
or environmental site assessment (a so-called Phase II ESA). This includes holes advanced to collect soil samples, water samples or rock cores, to advance in situ
sampling equipment, or to install monitoring wells or piezometers
. Samples collected from boreholes are often tested in a laboratory to determine their physical properties, or to assess levels of various chemical constituents or contaminants.
Typically, a borehole used as a water well
is completed by installing a vertical pipe (casing) and well screen to keep the borehole from caving. This also helps prevent surface contaminants from entering the borehole and protects any installed pump from drawing in sand and sediment. Oil and natural gas wells
are completed in a similar, albeit usually more complex, manner.
- 05 Dec 2011