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UNIFIED SOIL CLASSIFICATION SYSTEM <br />Major Divisions <br />grf <br />Itr <br />Description <br />Major Divisions <br />grf <br />Itr <br />Well -graded gravels or gravel sand <br />t <br />GW <br />Inorganic silts and very fine sands, <br />Gravel <br />mixtures, little or no fines <br />Silts <br />ML <br />rock flour, silty or clayey fine sands <br />and <br />And <br />or clavey silts with sli ht plasticity <br />Inorganic clays of low to medium <br />Gravelly <br />Soils <br />GP <br />Poorly -graded gravels or gravel <br />Clays <br />$, <br />sand mixture, little or no fines <br />LL,<50 <br />CL <br />plasticity, gravelly clays, sandy <br />More <br />clays, silty clays, lean clays <br />GM <br />Silty gravels, gravel -sand -silt <br />Coarse <br />mixtures <br />Organic silts and organic silt -clays <br />.an50% <br />of coarse <br />fraction <br />Grained <br />OL <br />Of IOW p18StlClty <br />Grained relained <br />Clayey gravels, gravel -sand -clay <br />on No, 4 <br />sieve <br />GC <br />mixtures <br />Soils <br />Inorganic silts, micaceous or <br />Soils <br />MH <br />diatomaceous fine or silty soils, <br />-- — <br />Well -graded sands or gravelly <br />Sand <br />- <br />SW <br />sands, little or no fines <br />Af ore than <br />5Css, passes <br />Silts <br />e18S11C SIIfS <br />Inorganic clays of high plasticity, <br />9 Y 9 P ty, <br />More than and <br />eor <br />on No 20o <br />And <br />SIP <br />sands or gravelly <br />retained on Sandy <br />sieve <br />sieve <br />Clays <br />VH <br />fat clays <br />No 200 Soils <br />.:., <br />sands, little or no fines <br />LL,<50 <br />_ <br />sieve <br />Organic clays of medium to high <br />M°`° <br />mansoi <br />' : <br />SM <br />Silt sands, sand -silt mixtures <br />Y <br />OH <br />plasticity <br />ofcoarse <br />---- _. <br />fracM1on <br />,SC <br />Clayey sands, and -clay mixtures <br />Highly Organic <br />PT <br />Peat and other highly organic soils <br />onallo- 4 <br />sieve <br />Soils <br />ovulvUHl[ r I,LAooir II,H I Iurv: boos possessing characteristics of two groups are designated by combinations of group symbols <br />PARTICLE SIZE LIMITS <br />U.S. STANDARD SERIES SIEVE CLEAR SQUARE SIEVE OPENINGS <br />200 40 10 4 3/4" 3" 12" <br />Silts Sand Gravel <br />and Cobbles Boulders <br />Clays Fine Medium Coarse_ Fine Coarse y� <br />RELATIVE DENSITY <br />Sands and Gravels <br />Blows/Foot (SPT) <br />Very Loose <br /><4 <br />Loose <br />4-10 <br />Medium Dense <br />11-30 <br />Dense <br />31-50 <br />Very Dense <br />>50 <br />LABORATORY TESTS <br />Symbol <br />Test <br />Direct Shear <br />DS <br />DSR <br />Direct Shear <br />CON <br />(Remolded) <br />SA <br />Sieve Analysis <br />MAX <br />Maximum Density <br />RV <br />Resistance (R) Value <br />El <br />Expansion Index <br />SE <br />Sand Equivalent <br />AL <br />Atterberg Limits <br />CHEM <br />Chemical Analysis <br />HY <br />Hydrometer Analysis <br />KEY T <br />CONSISTENCY CLASSIFICATION <br />Silts and Clays <br />Criteria <br />Very Soft <br />Thumb penetrates soil >1 in. <br />Soft <br />Thumb penetrates soil 1 in, <br />Firm <br />Thumb penetrates soil 1/4 in <br />Stiff <br />Readily indented with thumbnail <br />Very Stiff <br />Thumbnail will not indent soil <br />SOIL MOISTURE <br />Increasing V6sual Moisture Content <br />Dry - Dry to touch <br />Moist - Damp, but no visible free water <br />wet - Visible free water <br />HARDNESS <br />Bedrock <br />Soft <br />Moderately Hard <br />Hard <br />Very Hard <br />SIZE PROPORTIONS <br />Trace - <5% <br />Few - 5 to 10% <br />Some - 15 to 25% <br />ALTA CALIFORNIA GEOTECHNICAL INC. <br />City Council 18 — 856 10/3/2023 PLATE B <br />