Agenda - Public Works Committee - 12/18/2018

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Brookview Estates Reconstruction Ramsey, Minnesota NTI Project No. 18.MSP06855.000 CLASSIFICATION of SOILS for ENGINEERING PURPOSES ASTM Designation D-2487 and D2488 (Unified Soil Classification System) Group Major Divisions Typical NameClassification Criteria Symbol 50% or more of coarse fraction Clean Gravels Well graded gravels and Borderline Classification requiring use Cu = D60 / D10 greater than 4. GW gravel-sand mixtures, little retained on No. 4 sieve.Cz = (D30)2 / (D10 x D60) between 1 & 3. or no fines. Poorly graded gravels and GP gravel-sand mixtures, little Not meeting both criteria for GW materials. Gravels More than 50% retained on No. 200 sieve * or no fines. Gravels with Fines Atterberg limits Silty gravels, gravel-sand-GW, GP, SW, SP Atterberg limits GM, GC, SM, SC GM silt mixtures. plotting in hatched Classification on basis of percentage of fines. P.I. less than 4. area are borderline Course Grained Soils Atterberg limits classifications Clayey gravels, gravel-sand- GC requiring use of dual clay mixtures. with P.I. greater symbols. From 5% to 12% passing No. 200 Sieve: than 7. More than 12% passing No. 200 Sieve: More than 50% of coarse fraction Less than 5% passing No. 200 Sieve: Well-graded sands and Cu = D60 / D10 greater than 6. Clean Sands SW gravelly sands, little or no Cz = (D30)2 / (D10 x D60) between 1 & 3. fines. passes No 4 sieve. Poorly-graded sands and SP gravelly sands, little or no Not meeting both criteria for SW materials. Sands fines. of duel symbols. Atterberg limits Atterberg limits Sands with Silty sands, sand-silt SM plotting in hatched mixtures. Fines P.I. less than 4. area are borderline Atterberg limits classifications Clayey sands, sand-clay SC requiring use of dual mixtures. with P.I. > 7. symbols. Inorganic silts, very fine Liquid Limit of 50% or less ML sands, rock flour, silty or clayey fine sands. Silts and Clays Inorganic clays of low to More than 50% passes No. 200 sieve * medium plasticity, gravelly CL clays, sandy clays, silty clays, lean clays. Fine Grained Soils Organic silts and organic OL silty clays of low plasticity. Liquid Limit greater than Inorganic silts, micaceous MH or diatomaceous fine sands Silts and Clays or silts, elastic silts. 50%. Inorganic clays of high CH plasticity, fat clays. Organic clays of medium to OH high plasticity. Highly Organic Soils Peat, muck and other Pt Plasticity Limit highly organic soils.