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UNIFIED SOIL CLASSIFICATION SYSTEM Soil Classification Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests Group Group Name Symbol Gravels: Clean Gravels: Cu>_4 and 1 5 Cc<3 E GW Well-graded gravel P More than 50%of Less than 5%fines c Cu<4 and/or 1>Cc>3 E GP Poorly graded gravel' coarse fraction retained Gravels with Fines: Fines classify as ML or MH GM silty gravel Coarse Grained Soils: on No.4 sieve More than 12%finest Fines classify as CL or CH GC Clayey gravel More than 50%retainedClean Sands: Cu>_6 and 1 5 Cc< E E SW Well-graded sand' on No.200 sieve Sands: SP Poorly graded sand'/° Less than 5 foes° Cu<6 and/or 1>Cc>3E 50/°or more of coarse ° fraction passes No.4 Sands with Fines: Fines classify as ML or MH SM Silty sand°'"41 sieve More than 12%fines° Fines classify as CL or CH SC Clayey sand°' PI>7 and plots on or above"A"line' CL Lean clay"`' a Silts and Clays: Inorganic: PI<4 or plots below"A°line ML Silt Liquid limit less than 50 Liquid limit-oven dried <0.75 OL Organic clay '`'"' Fine-Grained Soils: Organic: Liquid limit-not dried Organic silt 50%or more passes the PI plots on or above"A"line CH Fat clay No.200 sieve Silts and Clays: P Inorganic: PI lots below"A"line MH Elastic Silt"' 'M Liquid limit 50 or more Liquid limit-oven dried Organic clay"'`'"'P Organic: <0.75OH Or anic silt"'`'"''° Liquid limit-not dried 9 Highly organic soils: Primarily organic matter,dark in color,and organic odor PT Peat "Based on the material passing the 3-inch(75-mm)sieve "If fines are organic,add"with organic fines"to group name. B If field sample contained cobbles or boulders,or both,add with cobbles If soil contains>_15%gravel,add"with gravel"to group name. or boulders,or both"to group name. ' If Atterberg limits plot in shaded area,soil is a CL-ML,silty clay. c Gravels with 5 to 12%fines require dual symbols: GW-GM well-graded "If soil contains 15 to 29%plus No.200,add"with sand"or"with gravel," gravel with silt,GW-GC well-graded gravel with clay,GP-GM poorly whichever is predominant. graded gravel with silt,GP-GC poorly graded gravel with clay. ` If soil contains>_30%plus No.200 predominantly sand,add"sandy"to °Sands with 5 to 12%fines require dual symbols: SW-SM well-graded group name. sand with sift,SW-SC well-graded sand with clay,SP-SM poorly graded M If soil contains s 30%plus No.200,predominantly gravel,add sand with silt,SP-SC poorly graded sand with clay "gravelly'to group name. ( z "PI z 4 and plots on or above"A"line. E Cu=DedDi° Cc PI<4 or plots below"A"line. = D x D PPI plots on or above"A"line. 0 00 °PI plots below"A°line. F If soil contains_15%sand,add"with sand"to group name. G If fines classify as CL-ML,use dual symbol GC-GM,or SC-SM. 60For classification of fine-grained soils and fine-grained fraction 50 of coarse-grained soils Equation of"A"-line EL Horizontal at PI=4 to LL=25.5. ; X 40 then PI=0.73 a0� Lu Equation of"U"-line Geo Z Vertical at LL—_16 to PI=7, Y 30 then PI=0.9(LL-8) f— / V U � c�0 7/F F_ zo MH or OH W 10 7 - L- L ML or OL 4 - o - 0 10 16 20 30 40 50 60 70 80 90 100 110 LIQUID LIMIT(LL) 1 rerracon Exhibit C-2