Geotechnical investigations, conducted by geotechnical engineers or engineering geologists, gather crucial information on the physical properties of soil, earthworks, and foundations for planned structures, as well as for addressing issues in existing earthworks and structures caused by subsurface conditions. These investigations, known as site investigations, are also essential for measuring the thermal resistance of soils or backfill materials needed for underground transmission lines, oil and gas pipelines, radioactive waste disposal, and solar thermal storage facilities. A typical geotechnical investigation involves both surface and subsurface exploration of a site, sometimes employing geophysical methods to collect data. Subsurface exploration generally includes soil sampling and laboratory testing of the retrieved samples.