A geotechnical investigation is a site-specific study of soil and groundwater conditions, producing the bearing capacity, expansion potential, and liquefaction susceptibility data the structural engineer needs to design the foundation. It includes test borings with Standard Penetration Tests (SPT), laboratory soil testing using the Unified Soil Classification System (USCS), groundwater table determination, and a geotechnical report with foundation recommendations. On the Wasatch Front, geotechnical investigation is particularly important because Lake Bonneville lacustrine clay deposits in valley floor areas have variable bearing capacity, expansion potential, and potential liquefaction susceptibility. Most Utah building departments require a geotech investigation for hillside lots, lots with known soil instability, and new construction where the building official determines it’s needed.