Agenda - Public Works Committee - 01/21/2025

Home

Unified Soil Classification (USC) System (from ASTM D 2487) Major Divisions Course -Grained Soils More than 50% retained on the 0.075 mm (No. 200) sieve Fine -Grained Soils More than 50% passes the 0.075 mm (No. 200) sieve Gravels 50% or more of course fraction retained on the 4.75 mm (No. 4) sieve Sands 50% or more of course fraction passes the 4.75 (No. 4) sieve Clean Gravels Gravels with Fines Clean Sands Sands with Fines Silts and Clays Liquid Limit 50% or less Silts and Clays Liquid Limit greater than 50% Group Symbol GW GP GM GC SW SP SM SC ML CL OL MH CH OH Highly Organic Soils PT Prefix: G = Gravel, S = Sand, M = Silt, C = Clay, 0 = Organic Suffix: W = Well Graded, P = Poorly Graded, M = Silty, L = Clay, LL < 50%, H = Clay, LL > 50% Typical Names Well -graded gravels and gravel -sand mixtures, little or no fines Poorly graded gravels and gravel -sand mixtures, little or no fines Silty gravels, gravel -sand -silt mixtures Clayey gravels, gravel -sand -clay mixtures Well -graded sands and gravelly sands, little or no fines Poorly graded sands and gravelly sands, little or no fines Silty sands, sand -silt mixtures Clayey sands, sand -clay mixtures Inorganic silts, very fine sands, rock four, silty or clayey fine sands Inorganic clays of low to medium plasticity, gravelly/sandy/silty/lean clays Organic silts and organic silty clays of low plasticity Inorganic silts, micaceous or diatomaceous fine sands or silts, elastic silts Inorganic clays or high plasticity, fat clays Organic clays of medium to high plasticity Peat, muck, and other highly organic soils