406 PECKS DR Geotech Report 2025-07-14

SOIL CLASSIFICATION & PENETRATION TEST DATA EXPLANATION UNIFIED SOIL CLASSIFICATION SYSTEM (USCS) MAJOR DIVISION GROUP TYPICAL DESCRIPTION LABORATORY CLASSIFICATION CRITERIA SYMBOL WELL GRADED GRAVELS,GRAVEL-SAND Cu=(D60/D10)greater than 4 CLEAN GW MIXTURE,LITTLE OR NO FINES CONTENT Cc=(D30)2/(D10*D60)between 1 and 3 GRAVELS OF FINES BELOW GRAVELS (little or no GP POORLY GRADED GRAVELS,AND GRAVEL-SAND 5% CLEAN GRAVELS NOT MEETING ABOVE COARSE- (More Than Half fines) MIXTURES LITTLE OR NO FINES REQUIREMENTS GRAINED SOILS Coarse Fraction is Larger Than No.4 GM: ATTERBERG LIMITS BELOW"A"LINE. Sieve) DIRTY GM SILTY GRAVELS,GRAVEL-SAND-SILT MIXTURES CONTENT or P.I.LESS THAN 4 GRAVELS OF FINES EXCEEDS (with some GC CLAYEY GRAVELS,GRAVEL-SAND-CLAY 12% GC: ATTERBERG LIMITS ABOVE"A"LINE. fines) MIXTURES or P.I.MORE THAN 7 SANDS CLEAN SWWELL GRADED SANDS,GRAVELLY SANDS, Cu=(D60/D10)greater than 6 LITTLE OR NO FINES CONTENT Cc=(D30)2/(D10*D60)between 1 and 3 SANDS OF FINES BELOW (More Than Half (little 5% CLEAN SANDS NOT MEETING ABOVE or no POORLY GRADED SANDS,GRAVELLY SANDS, More Than Half Coarse Fraction is SP by Weight Larger Smaller Than No. fines) LITTLE OR NO FINES REQUIREMENTS Than No.200 4 Sieve) Sieve DIRTY SM SILTY SANDS,SAND-SILT MIXTURES ATTERBERG LIMITS BELOW"A"LINE with P.I.LESS THAN 4 SANDS CONTENT OF FINES EXCEEDS 12% (with some ATTERBERG LIMITS ABOVE"A"LINE SC CLAYEY SANDS,SAND-CLAY MIXTURES fines) with P.I.MORE THAN 7 SILTS Liquid Limit INORGANIC SILTS,ROCK FLOUR,SANDY SILTS (Below A-Line on <50% ML OF SLIGHT PLASTICITY 60 I I I I / Plasticity Chart, PLASTICITY CHART / FINE-GRAINED Negligible Liquid Limit INORGANIC SILTS,MICACEOUS OR 50- FOR SOIL PASSING / SOILS Organics) >50% MH DIATOMACEOUS,FINE SANDY OR SILTY SOIL NO.40 SIEVE / I INORGANIC CLAYS OF LOW PLASTICITY, o 40 /\ CH It CLAYS Liquid Limit r \ <50% CL GRAVELLY,SANDY,OR SILTY CLAYS,LEAN w / (Above A-Line on CLAYS 0 / U-Line Z A-Line Plasticity Chart, 30 / Negligible Liquid Limit INORGANIC CLAYS OF HIGH PLASTICITY,FAT >-- / Organics) >50% CH CLAYS U / Less Than Half by W 20 / Weight Larger ORGANIC SILTS Liquid Limit OL ORGANIC SILTS AND ORGANIC SILTY CLAYS OF g // CL MH or OH Than No.200 <50% LOW PLASTICITY 0_ / Sieve(i.e.,fines) &CLAYS 10 / (BelowA-Line on 7 ML cr OL PlasticityLiquid Limit �L-M_ Chart) 4 >50% OH ORGANIC CLAYS OF HIGH PLASTICITY ML 0 0 10 20 30 40 50 60 70 80 90 100 HIGHLY ORGANIC SOILS Pt PEAT AND OTHER HIGHLY ORGANIC SOILS LIQUID LIMIT(%) SOIL PARTICLE SIZE GENERAL GUIDANCE FOR ENGINEERING PROPERTIES OF SOILS,BASED ON STANDARD U.S.STANDARD SIEVE PENETRATION TEST(SPT)DATA FRACTION Passing Retained SANDY SOILS SILTY&CLAYEY SOILS Sieve Size Sieve Size Unconfined (mm) (mm) Blow Counts Relative Friction Angle Description Blow Counts Strength Clu, Description N Density, % A,degrees N SILT/CLAY #200 0.075 tsf SAND 0-4 0-15 Very Loose <2 <0.25 Very soft FINE #40 0.425 #200 0.075 4-10 15-35 26-30 Loose 2-4 0.25-0.50 Soft MEDIUM #10 2.00 #40 0.425 10-30 35-65 28-35 Medium Dense 4-8 0.50-1.00 Medium Stiff COARSE #4 4.75 #10 2.00 30-50 65-85 35-42 Dense 8-15 1.00-2.00 Stiff GRAVEL >50 85-100 38-46 Very Dense 15-30 2.00-4.00 Very Stiff FINE 0.75" 19 #4 4.75 >30 >4.00 Hard COARSE 3" 76 0.75" 19 COBBLES 76 mm to 203 mm GFO Group Northwest, Inc. BOULDERS >203 mm Geotechnical Engineers,Geologists,& Environmental Scientists ROCK >76 mm FRAGMENTS 13705 Bel-Red Road Bellevue,WA 98005 Phone(425)649-8757 E-mail:info@geogrourpnw.com ROCK >0.76 cubic meter in volume PLATE Al