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<br />~~S6 <br /> <br />. <br /> <br />Within 2 miles of the reservoir, to the north, the conduit crosses <br />bluffs formed by the Carlyle Shale, capped by the Fort Hayes Limestone <br />Member of the Niobrara Formation. The Carlyle Shale is stable <br />only in slopes of 10 degrees or less and erodes readily. Excavation <br />and compaction are moderately easy, and permeability is low. The <br />Fort Hayes Limestone beds have poor permeability, difficult <br />compaction, and excavation. Slope stability is excellent except <br />when undercut on dip slopes. <br /> <br />Approximately one-third of the conduit course lies across the <br />Pierre Shale, which is primarily a clayey shale. Excavation and <br />compaction are easy. Slope stability and ~rosion resistance are <br />poor and permeability is low. <br /> <br />The majority of the conduit route traverses unconsolidated <br />Quaternary alluvial units which can be easily excavated and <br />compacted. The Verdos Alluvium occurs at the northern end of <br />the route. It may be 100 feet thick and is composed of poorly <br />sorted gravel containing lenses of silt, sand and clay. In <br />areas near Security and Fountain, short areas of eolian sand are <br />traversed. Permeability of this unit is medium to high oepending <br />on clay content. It is readily eroded. Compaction may require <br />vibratory equipment. The central part of the conduit course <br />traverses Slocum Alluvium and Piney Creek Alluvium. Characteristics <br />vary locally. The Slocum Alluvium may contain ~ravel and <br />permeability will vary accordingly. It is generally resistant <br />to erosion. Slopes generally slump to 25 degrees or less. <br />Piney Creek Alluvium is firmly compacted clayey silt and sand, <br />with medium to low permeability, and poor to medium slope <br />stability. It may be easily erodable. <br /> <br />. <br /> <br />c. Economic Geology <br /> <br />The conduit does not traverse any areas of particular mineral <br />significance although some of the sedimentary units are productive <br />of nonmetallic materials in the general area, particularly sand <br />and gravel and limestone. Gravel occurs in the Fountain Creek <br />Alluvium, where it may be 30 to 50 feet thick, and gravel of <br />lesser quality occurs in the Verdos Alluvium. <br /> <br />Limestone is quarried from the Fort Hayes for cement rock and smelter <br />limestone. Eolian sand may serve as a source of material to be <br />used for soil cement and Pierre Shale has been used as a source 0f <br />clay for brick, tile, and light weight aggregate. <br /> <br />111-5 <br /> <br />. <br />