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Soil Classification Standard Operating Procedure SWE-FSOP-201;Revision 0 Ahtna Southwest Environmental Operations 4.1.4 Optional Descriptions Field soil descriptions may also include the following additional information based on project requirements or as time permits: • Gradation or Plasticity. Granular soil (sands or gravels) should be described as well-graded, poorly-graded, uniform, or gap-graded, depending on the gradation of the minus 3-inch fraction. Cohesive soil (silts or clays) should be described as non-plastic, low plastic, medium plastic, or highly plastic. • Dry Strength. Dry strength describes the crushing characteristics of a dry soil crumb of about 1/4- inch (5 millimeters [mm]) in diameter. If a crumb of dry soil is not available, remove particles larger than No. 40 sieve size, then mold at least three balls of soil about 1/4-inch (5 mm) in diameter to the consistency of putty, adding water if necessary.Allow the balls to dry completely by oven, sun, or air drying, and then test their strength by breaking and crumbling between the fingers.This strength is a measure of the character and quantity of the colloidal fraction contained in the soil.The dry strength increases with increasing plasticity. • Dilatancy. Dilatancy describes the soil's reaction to shaking. After removing particles larger than No. 40 sieve size, prepare a ball of moist soil about 1/2-inch (15 mm) in diameter. Add enough water, if necessary, to make the soil soft but not sticky. Place the ball in the open palm of one hand and shake horizontally, striking vigorously against the other hand several times. A positive reaction consists of the appearance of water on the surface of the ball, which then changes to a gelatinous consistency and becomes glossy. When the sample is squeezed between the fingers, the water and gloss disappear from the surface, the ball stiffens, and finally cracks or crumbles. The rapidity of appearance of water during shaking and of its disappearance during squeezing assist in identifying the character of the fines in a soil. • Toughness.Toughness is the consistency of the soil near the plastic limit.After removing particles larger than the No. 40 sieve size, mold a ball of soil about 1/2-inch (15 mm) in diameter to the consistency of putty. If too dry,water must be added. If too sticky,the specimen should be spread out in a thin layer and allowed to lose some moisture by evaporation.The specimen is then rolled out by hand on a smooth surface or between the palms into a thread about 1/8 inch (3 mm) in diameter. The thread is folded and rerolled repeatedly. During this manipulation, the moisture content is gradually reduced.The specimen stiffens,finally loses its plasticity, and crumbles when the plastic limit is reached. • Cementation. An estimate of cementation of a coarse-grained soil. • Relative Permeability. An estimate of the permeability based on visual examination of materials (e.g., high permeability for coarse sand and gravel versus low permeability for silty clay). The estimate should address the presence and condition of fractures (open, iron-stand, calcite-filled, open but clay-lined, etc.), as well as fracture density and orientation. • Local Geologic Name. Any specific local name or generic name (i.e., alluvium, loess). 4.1.5 Additional Borehole Descriptions The soil logs should also include a description of any tests run in the borehole; sample intervals, blow counts for drive samples, placement and construction details of piezometers,wells, and other monitoring equipment; geophysical logging techniques used; and notes on readings obtained by air monitoring instruments. Page 7 of 11