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<br />wrsr S~Nry and Snd%'ssn, LWit7 Fo~pna/Sver~,ry <br />' 2.6.2 Sixmile Soil <br />' The Sixmile Soil is moderately deep and well drained. It formed in residuum derived dominantly <br />' from red shale. Typically, the surface layer is light brown bouldery clay loam about 5 inches <br />thick. The underlying material to a depth of 38 inches is reddish brown clay loam. Red shale <br />' underlies the clay loam at a depth of 38 inches. <br />' Permeability of the Sixmile soil is moderately slow. Available water holding capacity is <br />moderate. Effective rooting depth is 20 to 40 inches. Runoff is medium to very rapid, and the <br />' hazazd of water erosion is moderate to very high. <br />' 2.7 Strstigraphy <br />' The uranium and vanadium ores of the Uravan Mineral Belt are located in the fine-to-medium <br />grained channel sandstones cif the Salt Wash member of the Morrison Formation. Depth of these <br />' strata vary from 10 feet to over 700 feet below land surface. The ore bodies aze lensoidal and <br />irregulaz, often varying in thickness from a few inches to several feet in short lateral distances. <br />' Mine workings aze primarily confined to ore-bearing sandstone. The stratigraphic unit beneath <br />the ore-bearing sandstone is a mudstone unit about 40 feet thick; however, because ore deposition <br />' elevations vary, the thickness of mudstone below the ore zone also varies. <br />In teens of potential impacts of surface storage of ore or waste rock at land surface on <br />groundwater quality, the irre~;ulaz distribution of ore zones, combined with the low permeability <br />' and associated low infiltration rates in surface soils, suggests that elevated levels of uranium or <br />other minerals in groundwater could be produced naturally by ore zones in contact with <br />' groundwater. Infiltration and transport to groundwater of these relatively immobile elements <br />' H:\USFAS~6TnWP~AaIALLET1EA595\WSI.NSUN RiT <br />Page 7 <br />1 <br />