Geotechnical variability is a complex feature that results from many independent sources of uncertainties, and is mainly affected by inherent variability and measurement errors. This study evaluates the coefficient of variation (COV) of soil properties and soil layers at Song-do region in Korea. Since soil variability is sensitive to soil layers and soil types, the Cays by soil layers (reclaimed layer and marine layer) and the COVs by soil types (clay and silt) were separately evaluated. It is observed that geotechnical variability of marine layer and clay is relatively smaller than that of reclamation layer and silt. And, the highly weathered rock and soil show the higher cays in the interpretation of the strength parameters of the fresh and weathered rock. And the proposed COV of Songdo area can be used for the reliability-based design procedure.