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Soil Series Correlation. Correlation of site-specific soils with NRCS soil series criteria was <br />• completed. All soils, except for Ustic Torriothents and Cryoborolls were associated with <br />established or tentative series and correlated easily. A higher taxonomic classification for Map <br />Units 99 (Cryoborolls) and 101 IUstic Torriorthents/Rock Outcrop) was not possible due to <br />highly variable physical properties. These soils occur outside of the projected disturbance area. <br />Detailed descriptions were prepared for these map units in 1979; however, soil samples were <br />not collected. Six series variants, Aaberg variant (shallow), Cochetopa variant Imoderately <br />deep), Lymanson variant (shallow), Roxal variant Imoderately deep), Spicerton variant (frigid <br />summer soil temperatures), and Splitro variant (stony phase) were mapped within the study <br />area. Some of the Coutis and Skyway profiles are also considered variants since lab analysis <br />indicates the control sections would be placed in the fine-loamy family. No new soil series 'i <br />names were proposed as Dart of this survey. <br />Prime Farmland Determination. The NRCS determined that no prime farmland exists in Routt <br />County because of cold temperatures and a short growing season ISCS, October 1982 and <br />SCS, 19801 A letter from the NRCS dated March 78, 1981 concerning prime farmland was <br />originally presented in Appendix 9-5. Amore recent letter confirming no prime farmland (dated <br />10/17/971, is presented as an updated replacement in Appendix 9-5. SCC therefore requests a <br />negative determination for the entire Seneca II-W/11-W South Extension Area based upon this <br />NRCS information which meets DMG Rule 2.04.12{2,31 negative determination requirements. <br />• Alluvial Soils. The results of the soil survey, in conjunction with evaluation of available <br />geologic maps and aerial photography, indicate two stream drainages exist within and adjacent <br />to the mine permit and tie-across haul road corridor areas where unconsolidated streamlain <br />deposits and alluvial soils are present. These are Hubberson Gulch near the mine access road <br />and Dry Creek near the tie-across haul road corridor. Both contain recent stratified stream <br />alluvium, with areas of less than ten acres that can be considered naturally subirrigated. A <br />detailed discussion of alluvial valley floor conditions is presented in Tab 7 of this PAP. The <br />following is a general discussion of alluvial soils in these drainages. <br />The Dry Creek alluvium, in the Tie-Across Haul Road corridor, has a vegetation cover of four- <br />wing saltbush and fortis. Farming of this area is prohibited by highly saline and sodic soils and <br />lack of a developed water supply system. <br />The lower Hubberson Gulch valley bottomland, from approximately one-quarter mile southeast <br />of the Smith ranch house to its confluence with Water Trough Gulch near the Hayden Divide <br />county road, contains unconsolidated streamlain deposits and alluvial soils and is currently used <br />predominantly for irrigated grass hayland. Some additional areas adjacent to the bottomland <br />are used for pastureland but are not irrigated. No wheat cropland currently exists in the <br />• bottomland or adjacent areas. <br />17 Revised 9/98 <br />