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Descriptive Terminology of Soil Based on Standards ASTM D2487/2488 (Unified Soil Classification System) Group Symbol Group NameB Cu ≥ 4 and 1 ≤ Cc ≤ 3D GW Well-graded gravelE Cu < 4 and/or (Cc < 1 or Cc > 3)D GP Poorly graded gravelE Fines classify as ML or MH GM Silty gravelE F G Fines Classify as CL or CH GC Clayey gravelE F G Cu ≥ 6 and 1 ≤ Cc ≤ 3D SW Well-graded sandI Cu < 6 and/or (Cc < 1 or Cc > 3)D SP Poorly graded sandI Fines classify as ML or MH SM Silty sandF G I Fines classify as CL or CH SC Clayey sandF G I CL Lean clayK L M PI < 4 or plots below "A" lineJ ML SiltK L M Organic OL CH Fat clayK L M MH Elastic siltK L M Organic OH PT Peat Highly Organic Soils Silts and Clays (Liquid limit less than 50) Silts and Clays (Liquid limit 50 or more) Primarily organic matter, dark in color, and organic odor Inorganic Inorganic PI > 7 and plots on or above "A" lineJ PI plots on or above "A" line PI plots below "A" line Criteria for Assigning Group Symbols and Group Names Using Laboratory TestsA Soil Classification Coarse-grained Soils (more than 50% retained on No. 200 sieve)Fine-grained Soils (50% or more passes the No. 200 sieve) Sands (50% or more coarse fraction passes No. 4 sieve) Clean Gravels (Less than 5% finesC) Gravels with Fines (More than 12% finesC) Clean Sands (Less than 5% finesH) Sands with Fines (More than 12% finesH) Gravels (More than 50% of coarse fraction retained on No. 4 sieve) Liquid Limit −oven dried Liquid Limit −not dried <0.75 Organic clay K L M N Organic silt K L M O Liquid Limit −oven dried Liquid Limit −not dried <0.75 Organic clay K L M P Organic silt K L M Q Particle Size Identification Boulders.............. over 12" Cobbles................ 3" to 12" Gravel Coarse............. 3/4" to 3" (19.00 mm to 75.00 mm) Fine................. No. 4 to 3/4" (4.75 mm to 19.00 mm) Sand Coarse.............. No. 10 to No. 4 (2.00 mm to 4.75 mm) Medium........... No. 40 to No. 10 (0.425 mm to 2.00 mm) Fine.................. No. 200 to No. 40 (0.075 mm to 0.425 mm) Silt........................ No. 200 (0.075 mm) to .005 mm Clay...................... < .005 mm Relative ProportionsL, M trace............................. 0 to 5% little.............................. 6 to 14% with.............................. ≥ 15% Inclusion Thicknesses lens............................... 0 to 1/8" seam............................. 1/8" to 1" layer.............................. over 1" Apparent Relative Density of Cohesionless Soils Very loose ..................... 0 to 4 BPF Loose ............................ 5 to 10 BPF Medium dense.............. 11 to 30 BPF Dense............................ 31 to 50 BPF Very dense.................... over 50 BPF A.Based on the material passing the 3-inch (75-mm) sieve. B.If field sample contained cobbles or boulders, or both, add "with cobbles or boulders, or both" to group name. C. Gravels with 5 to 12% fines require dual symbols: GW-GM well-graded gravel with silt GW-GC well-graded gravel with clay GP-GM poorly graded gravel with silt GP-GC poorly graded gravel with clay D.Cu = D60 / D10 Cc = 𝐷30 2 / (𝐷10 𝑥𝐷60) E.If soil contains ≥ 15% sand, add "with sand" to group name. F.If fines classify as CL-ML, use dual symbol GC-GM or SC-SM. G. If fines are organic, add "with organic fines" to group name. H. Sands with 5 to 12%fines require dual symbols: SW-SM well-graded sand with silt SW-SC well-graded sand with clay SP-SM poorly graded sand with silt SP-SC poorly graded sand with clay I.If soil contains ≥ 15% gravel, add "with gravel" to group name. J. If Atterberg limits plot in hatched area, soil is CL-ML, silty clay. K.If soil contains 15 to < 30% plus No. 200, add "with sand" or "with gravel", whichever is predominant. L. If soil contains ≥ 30% plus No. 200, predominantly sand, add “sandy” to group name. M. If soil contains ≥ 30% plus No. 200 predominantly gravel, add “gravelly” to group name. N. PI ≥ 4 and plots on or above “A” line. O. PI < 4 or plots below “A” line. P. PI plots on or above “A” line. Q.PI plots below “A” line. Laboratory Tests DD Dry density,pcf OC Organic content, %LL Liquid limit WD Wet density, pcf qp Pocket penetrometer strength, tsf PL Plastic limit P200 % Passing #200 sieve MC Moisture content, %PI Plasticity index qU Unconfined compression test, tsf Consistency of Blows Approximate Unconfined Cohesive Soils Per Foot Compressive Strength Very soft................... 0 to 1 BPF................... < 0.25 tsf Soft........................... 2 to 4 BPF................... 0.25 to 0.5 tsf Medium.................... 5 to 8 BPF .................. 0.5 to 1 tsf Stiff........................... 9 to 15 BPF................. 1 to 2 tsf Very Stiff................... 16 to 30 BPF............... 2 to 4 tsf Hard.......................... over 30 BPF................ > 4 tsf Drilling Notes: Blows/N-value: Blows indicate the driving resistance recorded for each 6-inch interval. The reported N-value is the blows per foot recorded by summing the second and third interval in accordance with the Standard Penetration Test, ASTM D1586. Partial Penetration:If the sampler could not be driven through a full 6-inch interval, the number of blows for that partial penetration is shown as #/x" (i.e. 50/2"). The N-value is reported as "REF" indicating refusal. Recovery: Indicates the inches of sample recovered from the sampled interval. For a standard penetration test, full recovery is 18", and is 24" for a thinwall/shelby tube sample. WOH: Indicates the sampler penetrated soil under weight of hammer and rods alone; driving not required. WOR: Indicates the sampler penetrated soil under weight of rods alone; hammer weight and driving not required. Water Level: Indicates the water level measured by the drillers either while drilling ( ), at the end of drilling ( ), or at some time after drilling ( ). Moisture Content: Dry:Absence of moisture, dusty, dry to the touch. Moist: Damp but no visible water. Wet: Visible free water, usually soil is below water table. 3/2019