The new County Government Facility in San Luis Obispo is a 6-level structure: two levels of subterranean parking, and four above-ground levels. The total site area is approximately 38,000 square feet. The majority of the structure is of cast-in-place concrete construction. The uppermost level is of steel moment frame construction. The structure utilizes a mat foundation. The primary geotechnical concerns for the site development were the variable nature of underlying soils, significant depths of undocumented fill, the presence of existing basements in structures to be removed, and the potential for undue total or differential settlement, subsurface water, and the expansive nature of the soil. Earth Systems conducted a soils engineering investigation entailing site reconnaissance, field exploration, laboratory testing, and geotechnical analysis. Previously, an arm of the San Luis Creek had flowed through the site, and the Earth Systems team reviewed historical documents to help assess the possible effects on the project. Preliminary geotechnical recommendations for site preparation, shoring and underpinning, grading, utility trenches, foundations, slabs-on-grade, retaining walls, and pavement sections were developed. Additionally, Earth Systems conducted a Phase I environmental site assessment to evaluate areas of potential environmental concern as a result of past site usages. During construction, Earth Systems performed construction testing and inspection services such as grading observation and testing, asphalt inspection and testing, concrete sampling and testing, masonry sampling and testing, concrete batch plant inspection, special inspection of masonry, welding, epoxy anchor bolts, and inspection of excavations, and tie-back stressing.