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1 <br />characteristics that affect topsoil suitability. <br />' I.2.1 Hesperus Loam, Three to Six Percent Slopes <br />' This map unit occurs on low terraces along the drainages, <br />t <br />f th <br />f <br />hill <br />d <br />i <br />di <br /> oot <br />s an <br />ncluding the Rito Seco, lea <br />ng ou <br />o <br />e <br /> mountains slopes to the west. Very few areas of this soil type <br />' will be disturbed by project activities. Soils in this map unit <br /> formed in sandy and gravelly alluvial material principally from <br />' sandstones and weathered conglomerate with some mixtures of <br /> igneous rock. Hesperus soils have a dark gray brown loam <br />' surface layer eight- to ]2-inches thick underlain by alight <br /> brown sandy subsoil 20- to 30-inches thick. The underlying <br /> layers are poorly sorted, slightly cemented gravelly loamy sand <br />' to depths exceeding 10 ft. There is a lag gravel surface except <br /> under shrubs where organic matter collects to three inches. <br /> Sand and gravel lenses occur throughout the profile. <br /> Contrasting soils that may occur in this unit are sandy and <br />' fine sandy loamy on 0 to 3 percent slopes. Hesperus soils are <br /> suitable for growth medium to 36 inches, but the top 24 inches <br /> have better water capacity. The runoff from these soils is <br /> slow, and the hazard for water erosion is slight. The principal <br /> vegetation type on this soil is sagebrush shrub, and the range <br />' site is classified in the Valley Bench by the S(:S. <br />' I.2.2 Blackhall Gravelly Sandy Loam, 5 to 15 Percent Slopes <br />' This map unit occurs on the sides and slopes of the <br />valleys and low ridges on the site, and was formed in alluvium <br />1 and colluvium from sandstone and conglomerate. It is the common <br />soil type in the central and western portions o* the project <br />' site where the southern waste rock disposal area and the leach <br />pad and dewatered tailings disposal site are located. Blackhall <br />soils hae a dark brown sandy loam surface layer six-to eight- <br />' inches thick, underlain by a brown loamy sand l.o fine sandy <br />subsoil 20 to 30 inches thick. The soil may have weathered <br />1 <br />I-4 <br />