Laserfiche WebLink
K Kennedy Jenks <br /> Many soils have characteristics that are not clearly associated with a specific soil group. These soils <br /> might be near the borderline between groups, based on either grain-size grading and distribution, or <br /> plasticity characteristics. In this case, assigning dual group names and symbols might be <br /> appropriate (e.g., GW-GC or ML-CL). <br /> The two basic soil groups are: <br /> 1. Coarse-Grained Soils — For soils in this group, more than half of the material is larger than <br /> No. 200 sieve (0.074 mm). <br /> 2. Fine-Grained Soils (including Organic Soils) — For soils in this group, one half or more of the <br /> material is smaller than No. 200 sieve (0.074 mm). <br /> Note: No. 200 sieve is the smallest size that can be seen with the naked eye. <br /> CA Classification of Coarse-Grained Soils <br /> Coarse-grained soils are classified on the basis of: <br /> 1. Grain size and distribution <br /> 2. Quantity of fine-grained material (i.e., silt and clay) <br /> 3. Character of fine-grained material <br /> Classification uses the following symbols: <br /> Basic Symbols Modifying Symbols <br /> G - gravel W - well graded <br /> S - sand P - poorly graded <br /> M - with silt fines <br /> C - with clay fines <br /> The following are basic facts about coarse-grained soil classification: <br /> • The basic symbol G is used if the estimated volume percentage of gravel is greater than that <br /> for sand. In contrast, the symbol S is used when the estimated volume percentage of sand <br /> is greater than the percentage of gravel. <br /> • Gravels include material in the size range from 3 inches to 0.2 inch (i.e., retained on No. 4 <br /> sieve). Sand includes material in the size range from 0.2 inch to 0.003 inch. Use the grain <br /> size scale used by engineers (ASTM Standards D422-63 and D643-78) to further classify <br /> grain size as specified by the USCS. <br /> • Although not specifically treated in ASTM D2488-06, cobbles range in size from 3 inches to <br /> 10 inches and boulders refer to particles with a single dimension greater than 10 inches. <br /> They are included here for the purpose of completeness and for their hydrogeologic <br /> significance. <br /> Monitoring Well Installation Work Plan, B-3 <br /> The Wine Group, Franzia Winery, Ripon, CA <br /> P.\1 S-Proj\2003-post archive\030120.XY_GW Mon Well Support\09-Reports\piecesWPP_C SOG Borehole Log.doc <br />