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I Specific level depends upon clay mineralogy, soil texture, and saturation percentage according to Dollhopf et al., <br />1983. <br />a The specific percentage of clay or sand allowed will depend upon clay mineralogy, organic matter content, <br />consistence, soil lift, spoil characteristics, and size of sand fraction. <br />5 These values may vary depending upon the plant species proposed for revegetation in specific locations (e.g., a <br />soil with a high coarse fragment content throughout its profile may be completely salvaged if used for rangeland <br />versus cropland postmine land use). Prime farmland will not have >10% cobbles and boulders (3 inches mean <br />diameter and greater) and 15% coarse fraction (caught in a 2 millimeter sieve) by volume. The % volume is <br />estimated visually. <br />'This value for selenium was chosen based on guidance from Dave Dearstyne of NRCS and recent data that other <br />states are using. Dave is currently working extensively (2008) with the Selenium Task Force on the western slope <br />and is very knowledgeable about this issue. He basically stated that there is no concern for selenium unless Mancos <br />shale strata is being placed near the surface. At the new Horizon #2 Mine, no Mancos shale is placed near the <br />surface. Also, all tests of selenium in the pre-mine soil survey of 1998 show all values less than 0.1 ppm. The <br />suitability report of the bench 1 material used as subsoil on the previously backfilled portion of the Morgan property <br />in early 2008 show <1 ppm in all tests. Dave Dearstyne believes a threshold suitability level of 0.2 ppm in the Lift A <br />material and 1.0 ppm in the Lift B material is adequate. These are the levels proposed. <br />In cases where the Bench 1 material is used as the Lift B soil in prime farmland, it will meet the <br />specifications for Lift B, as outlined in Table 2.04.9-2. <br />These suitability evaluations, based on averages across the study area, were used for topsoil <br />volume determinations presented in the Topsoil Management Plan section of this Section <br />2.05.4(2)(d), Topsoil (Redistribution). The number of profiles on which these averages are <br />based is noted in the Soil Profile descriptions range of characteristics. The recommended <br />topsoil salvage depths for each map unit are weighted averages of each major component of <br />the map unit (those listed in the map unit name - for both associations and complexes) as well <br />as major soil inclusions as presented within the map units. <br />(Revised July 2008) 2.05.4(2)(d)-15