APPENDIX B: SOIL CLASSIFICATION LEGEND <br />APPARENT CONSISTENCY OF COHESIVE SOILS (PECK, HANSON & THORNBURN 1974, AASHTO 1988) <br />Descriptor SPT N60 <br />(blows/foot)* <br />Pocket Penetrometer, <br />Qp (tsf) <br />Torvane <br />(tsf) Field Approximation <br />Very Soft < 2 < 0.25 < 0.12 Easily penetrated several inches by fist <br />Soft 2 – 4 0.25 – 0.50 0.12 – 0.25 Easily penetrated several inches by thumb <br />Medium Stiff 5 – 8 0.50 – 1.0 0.25 – 0.50 Penetrated several inches by thumb w/moderate <br />effort <br />Stiff 9 – 15 1.0 – 2.0 0.50 – 1.0 Readily indented by thumbnail <br />Very Stiff 16 – 30 2.0 – 4.0 1.0 – 2.0 Indented by thumb but penetrated only with great <br />effort <br />Hard > 30 > 4.0 > 2.0 Indented by thumbnail with difficulty <br />* Using SPT N60 is considered a crude approximation for cohesive soils. <br />APPARENT DENSITY OF COHESIONLESS <br />SOILS (AASHTO 1988) MOISTURE <br />(ASTM D2488-06) <br />Descriptor SPT N60 Value (blows/foot) Descriptor Criteria <br />Very Loose 0 – 4 Dry <br />Absence of moisture, dusty, dry to the touch, well <br />below optimum moisture content (per ASTM <br />D698 or D1557) Loose 5 – 10 <br />Medium Dense 11 – 30 Moist Damp but no visible water <br />Dense 31 – 50 Wet <br />Visible free water, usually soil is below water <br />table, well above optimum moisture content (per <br />ASTM D698 or D1557) Very Dense > 50 <br />PERCENT OR PROPORTION OF SOILS <br />(ASTM D2488-06) <br />SOIL PARTICLE SIZE <br />(ASTM D2488-06) <br />Descriptor Criteria Descriptor Size <br />Trace Particles are present but estimated < <br />5% Boulder > 12 inches <br />Few 5 – 10% Cobble 3 to 12 inches <br />Little 15 – 25% Gravel - Coarse <br /> Fine <br />¾ inch to 3 inches <br />No. 4 sieve to ¾ inch Some 30 – 45% <br />Mostly 50 – 100% Sand - Coarse <br /> Medium <br /> Fine <br />No. 10 to No. 4 sieve (4.75mm) <br />No. 40 to No. 10 sieve (2mm) <br />No. 200 to No. 40 sieve (.425mm) Percentages are estimated to nearest 5% in the field. <br />Use “about” unless percentages are based on <br />laboratory testing. Silt and Clay (“fines”) Passing No. 200 sieve (0.075mm) <br />UNIFIED SOIL CLASSIFICATION SYSTEM (ASTM D2488) <br />Major Division Group <br />Symbol Description <br />Coarse <br />Grained <br />Soils <br />(more than <br />50% retained <br />on #200 <br />sieve) <br />Gravel (50% or <br />more retained <br />on No. 4 sieve) <br />Clean <br />Gravel <br />GW Well-graded gravels and gravel-sand mixtures, little or no fines <br />GP Poorly graded gravels and gravel-sand mixtures, little or no fines <br />Gravel <br />with fines <br />GM Silty gravels and gravel-sand-silt mixtures <br />GC Clayey gravels and gravel-sand-clay mixtures <br />Sand (> 50% <br />passing No. 4 <br />sieve) <br />Clean <br />sand <br />SW Well-graded sands and gravelly sands, little or no fines <br />SP Poorly-graded sands and gravelly sands, little or no fines <br />Sand <br />with fines <br />SM Silty sands and sand-silt mixtures <br />SC Clayey sands and sand-clay mixtures <br />Fine Grained <br />Soils <br />(50% or more <br />passing #200 <br />sieve) <br />Silt and Clay <br />(liquid limit < 50) <br />ML Inorganic silts, rock flour and clayey silts <br />CL Inorganic clays of low-medium plasticity, gravelly, sandy & lean clays <br />OL Organic silts and organic silty clays of low plasticity <br />Silt and Clay <br />(liquid limit > 50) <br />MH Inorganic silts and clayey silts <br />CH Inorganic clays or high plasticity, fat clays <br />OH Organic clays of medium to high plasticity <br />Highly Organic Soils PT Peat, muck and other highly organic soils <br />GRAPHIC SYMBOL LEGEND <br />GRAB Grab sample <br />SPT Standard Penetration Test (2” OD), ASTM D1586 <br />ST Shelby Tube, ASTM D1587 (pushed) <br />DM Dames and Moore ring sampler (3.25” OD and 140-pound <br />hammer) <br />CORE Rock coring