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B.4.3 Classification of Fine-Grained Soils <br />Fine-grained soils are classified on the basis of: <br />Liquid limit <br />Plasticity <br />Classification uses the following symbols: <br />Basic Symbols <br />M - silt <br />C - clay <br />0 - organic <br />Pt - peat <br />Modifying Symbols <br />L - low liquid limit <br />H - high liquid limit <br />The following are basic facts about fine-grained soil classification: <br />The basic symbol M is used if the soil is mostly silt, while symbol C applies if it consists <br />mostly of clay. Use of symbol 0 indicates that organic matter is present in an amount <br />sufficient to influence soil properties. The symbol Pt indicates soil that consists mostly of <br />organic material. <br />Modifying symbols are based on the following hand tests conducted on a soil sample: <br />Dry strength (crushing resistance) <br />Dilatency (reaction to shaking) <br />Toughness (consistency near plastic limit) <br />Soil designated ML has little or no plasticity and can be recognized by slight dry strength, <br />quick dilatency, and slight toughness. <br />CL indicates soil with slight to medium plasticity, which can be recognized by medium to <br />high dry strength, very slow dilatency, and medium toughness. <br />OL is used to describe a soil that is less plastic than CL soil and can be recognized by slight <br />to medium dry strength, medium to slow dilatency, and slight toughness. <br />MH soil has slight to medium plasticity and can be recognized by low dry strength, slow <br />dilatency, and slight to medium toughness. <br />Soil designated CH has high plasticity and is recognizable by its high dry strength, no <br />dilatency, and high toughness. <br />OH soil is less plastic than CH soil and can be recognized by medium to high dry strength, <br />slow dilatency, and slight to medium toughness. <br />Additional Soil and Groundwater Sample Work Plan, Page 4 <br />BNSF Mormon Yard, Stockton, California <br />ONybnst21bnsfwplwp1201811899020 00_mormon_yard 1 work_plan_idlappb_sogboreholeiogging acpt chng_wp.doc