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PAGE 2 OF 3 OB/8/00 CONSTRUCTION MATERIALS Endnote -• CONSTRUCTION MATERIALS This report gives information about the soils as a source of roadfill, sand, gravel, end topsoil. The soils are rated "Good", "Fair", or "Poor" as a source of roadfill and topsoil. They are rated as a "Probable" or "Improbable" 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 compaction, minor processing, and other standard construction practices are assumetl. Each soil is evaluated to a depth of 5 or 6 feet. Roadf ill is soil material that is excavated in ane 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 end 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 and spreading. Many soils have layers of contrasting suitability within their profile. The report entitled Engineering Index Properties is also available and 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 no[ considered in the ratings. The ratings are based on soil properties, site features, and observed performance of [he soils. The thickness of suitable material is a major consideration. The ease of excavation is affected by large stones, a high water table, and slope. How well the soil performs in place after it has been compacted and drained is determined by its strength (as inferred from the engineering classification of the soil) and shrink-swell potential. Soils 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, few cobbles aM stones, and slopes of 15 percent or less. Depth to the water table is more than 3 feet Soils rated "Fair" have more than 35 percent silt- and clay-sized particles and have a plasticity of less than 10. They have a motlerate 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 7 foot, These soils may have layers of suitable material, but the material is less than 3 feet thick. Sand and gravel are natural aggregates suitable for canmerc ial use with a minimum of processing. Sand end 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, arW 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 must be at feast 3 feet thick and less than 50 percent, by weight, large stones. All other soils are rated as an "Improbable" source. Coarse fragments of soft bedrock, such as shale and siltstone, are not considered to be sand and gravel.