The designer of a super-structure foundation must invariably perform a detailed surface and subsurface (soil) exploration of the potential site prior to deciding on the nature and type of the foundation. The subsurface investigation program for a given site should account for the type, size, and importance of the proposed structure. These parameters help focus the design of the site exploration program by determining the quantity and depth of soil soundings (or borings) required. Planning for a site investigation should also include the location of underground utilities (i.e., phone, power, gas, etc.). As such, a local ‘‘call before you dig’’ service should be notified several days prior to the anticipated investigation. These services are usually subsidized by the various local utilities and have no associated cost. Subsurface exploration and testing specifically serve the following purposes (FHWA, 1998):