Both the USCS and the U.S. Dept. The USDA system is emphasized in the federal OSHA regulations, but the USCS is more consistent with the definitions and engineering terms of the regulatory codes. Advantages Concepts of the USCS are used at OSHA-SLTC in preference to other classical systems of soil classification. It is simple and can be used on-site. A qualitative analysis of silt and clay is not requied.
Dust is minimized by wet sample break down.
Gravel is treated as a major soil constituent. It is based on engineerging principles. Agricultural terms such as loam are not required. The property of plasticity is more adequately treated. There are no known disadvantages of the USCS compared to other recognized systems of soil classification for excavations.