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08/8/00 CONSTRUCTION MATERIALS ~ Endnote -- CONSTRUCTION MATERIALS This report gives information about the soils as a source of roadfill, send, gravel, and topsoil. The soils are rated "Good", "Fair", or "Poor" as a source of roadfill and topsoil. They are rated as a "Probable" or "Inlorobable" source of sand and gravel. The ratings are based on soil properties and site features that affect the removal of the soil and its use as construction material. Normal conpaction, minor processing, end other standard construction practices are asstmed. Each soil is evaluated to a depth of 5 or b feet. Roadfill is soil material that is excavated in one place and used in road embankments in another place. In this report, the soils are rated as a source of roadfill for low embankments, generally less than 6 feet high and less exacting in design than higher embankments. The ratings are for the soil material below the surface layer to a depth of 5 or 6 feet. It is assumed that soil layers will be mixed during excavating end spreading. Many soils have layers of contrasting suitability within their profile. The report entitled Engineering Index Properties is also available end it provides detailed information about each soil layer. This information can help determine the suitability of each layer for use as roadfill. the performance of soil after it is stabilized with lime or cement is not considered in the ratings. The ratings are based on soil properties, site features, and observed performance of the soils. The thickness of suitable material is a major consideration. The ease of excavation is effected by le rge stones, a high water table, and slope. How well the soil performs in place after i[ has been compacted and drained is determined by its strength (as inferred from the engineering classif itation of the soil) arxi shrink-swell potential. Soi .~ rated "Good" contain significant amounts of sand or gravel or both. They have at least 5 feet of suitable material, a low shrink-swell potential, feu cobbles and stones, end slopes of 15 percent or less. Depth to the water table is more than 3 feet Soils rated "Fair" have more than 35 percent si lt• and clay-sized particles arW have a plasticity of less than 10. They have a moderate shrink-swell potential, slopes of 15 to 25 percent, or many stones. Depth to the water table is 1 to 3 feet. Soils rated "Poor" have a plasticity index of more then 10, a high shrink-swell potential, many stones, or slopes of more than 25 percent. They are wet, and the depth to the water table is less than 1 foot. These soils may have layers of suitable material, but the materiel is less then 3 feet thick. Sand and gravel are natural aggregates suitable for conmercial use with a minimum of processing. Sand and gravel are used in many kinds of construction. Specifications for each use vary widely. In this report only the probability of finding material in suitable quantity is evaluated. The suitability of the material for specific purposes is not evaluated, nor are factors that affect excavation of the material. The properties used to evaluate the soil as a source of sand or gravel are gradation of grain sizes (as indicated by the engineering classification of the soil), the thickness of suitable material, and the content of rock fragments. Kinds of rock, acidity, and stratification are given in the soil series descriptions. Gradation of grain sizes is given in the Engineering Index Properties report. A soil rated as a "Probable" source has a layer of clean sand and gravel or a layer of sand or gravel that contains up to 12 percent silty fines. This material oust beat least 3 feet thick end less than 50 percent, by weight, large stones. All other sails ere rated as an "Improbable" source. Coarse fragments of soft bedrock, such es shale and sil*=*one, are not considered to be sand and gravel.