• Coarse Grained Soils: Soils that contain 50 % or less of soil particles passing a in. ( mm) opening. WSDOT Geotechnical Design Manual M Page 41 October 2013 • Fine Grained Inorganic Soils: Soils that contain more than 50 % of soil particles passing a in. ( mm) opening. • Fine Grained Organic Soils: Soils that contain enough organic particles to ...