A two-story reinforced concrete building is to be built on a vacant parcel of land. This building will be 100ft wide and 200 ft long. The foundations will be founded at a depth of 5 ft below the ground surface. Based on information from other borings on adjacent properties, you are reasonably certain that the soils below a depth of 5 to 8 feet (1.5 to 2.5 m) are strong and relatively incompressible. However, the upper soils are questionable because several uncompacted fills have been found in the neighborhood. Not only are these uncompacted fills loose, they have often contained various debris such as wood, rocks, and miscellaneous trash. However, none of these deleterious materials is present at the ground surface at this site. Determine the required number and depth of the exploratory borings.