The purpose of a Geotechnical Investigation is to determine the engineering qualities of the soils or rocks at a site, and how their location and depth affects an envisioned construction project. The presence of any buried organic materials with poor engineering qualities, obstructions to earthwork, and the depth of the water table are also important to identify during a geotechnical investigation. Prior to initiating expensive field work, an initial sense of soil conditions for specific localities may be obtained through government soil surveys that have been recorded for most of the United States. Geotechnical investigations prepared for adjacent construction projects are another potential source of available site information.