Soil Types MH CH ML CL ML CL SC GC SM CM SP GP SW Soils in the groups below require a granular bedding material instead of native soil bedding. Restrained lengths are calculated using GP or SP bedding material. Inorganic silts, micaceous or diatomaceous fine sands or silts, elastic silts, backfilled with granular material. Inorganic clays of high plasticity, backfilled with granular material. ML native soil backfilled with granular material Cl native soil backfilled with granular material Inorganic silts, very fine sands, rock flour, silty or clayey fine sands (backfilled using native soil) Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, lean clays (backfilled using native soil) Clayey sands, sand-clay mixtures Clayey gravels, gravel-sand-clay mixtures Silty sands,sand silt mixtures Silty gravels, gravel-sand-silt mixtures Poorly graded sands and gravelly sands, little or no fines Poorly graded gravels and gravel-sand mixtures, little or no fines Well-graded sands and gravelly sands, little or no fines (granular) (granular) (granular) Fine Grained Soils Well-graded gravels and gravel-sand mixtures, little or no fines Coarse Grained Soils (granular) GW