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Kennedy/Jenks Consultants 1. Observe basic properties and characteristics of the soil. These include grain-size grading and distribution and influence of moisture on fine-grained soil. 2. Assign the soil a USCS classification and denote it by the standard group name and symbol. 3. Provide a written description to differentiate between soils in the same group, if necessary. Many soils have characteristics that are not clearly associated with a specific soil group. These soils might be near the borderline between groups, based on either grain-size grading and distribution, or plasticity characteristics. In this case, assigning dual group names and symbols might be appropriate (e.g., GW-GC or ML-CL). The two basic soil groups are: 1. Coarse-Grained Soils — For soils in this group, more than half of the material is larger than No. 200 sieve (0.074 mm). 2. Fine-Grained Soils (including Organic Soils)— For soils in this group, one half or more of the material is smaller than No. 200 sieve (0.074 mm). Note: No. 200 sieve is the smallest size that can be seen with the naked eye. B.4 Classification of Coarse-Grained Soils Coarse-grained soils are classified on the basis of: 1. Grain size and distribution 2. Quantity of fine-grained material (i.e., silt and clay) 3. Character of fine-grained material Classification uses the following symbols: Basic Symbols Modifying Symbols G - gravel W-well graded S - sand P - poorly graded M - with silt fines C - with clay fines The following are basic facts about coarse-grained soil classification: • The basic symbol G is used if the estimated volume percentage of gravel is greater than that for sand. In contrast, the symbol S is used when the estimated volume percentage of sand is greater than the percentage of gravel. • Gravels include material in the size range from 3 inches to 0.2 inches (i.e., retained on No. 4 sieve). Sand includes material in the size range from 0.2 inches to 0.003 inches. Use the grain size scale used by engineers (ASTM Standards D422-63 and D643-78) to further classify grain size as specified by the USCS. Monitoring Well Installation Work Plan, B-3 Barrel Ten Quarter Circle Land Company, Escalon, California \\SFO\Groups\I S-Group\Admin\Job\03\030118.27_BTOC LC\09-Reports\M W-Install-WPI nlAppendiAAPP_BAm