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• Map Unit 6 - Topsoiled Regraded Spoil, 2 to 15 Percent Slopes <br />This neap unit is associated with the gently to moderately sloping upland <br />benches, ridgetops, and sideslopes. Vegetation consists primarily of <br />cheatgrass, crested wheatgrass, and Indian ricegrass. This map unit <br />occurs in areas which were previously mined. Following mining, spoil <br />piles were graded to approximate original contour, and suitable topsoil <br />was replaced. This map unit occurs on 10.1 percent of the study area <br />(Table 9-4-3). <br />The replaced topsoil and regraded spoil have suitable physical and <br />chemical properties (Tables 9-4-2 and 9-4-5). Typically, the regraded <br />spoil is slightly more acidic, has a higher sulfate content and has a <br />higher salinity than the replaced topsoil. Based upon six sampled <br />profiles, (Table 9-4-4) about six inches of suitable topsoil is <br />available for salvage within Map Unit 6. <br />Map Unit 7 - Topsoiled Disturbed Land, Shallow, 2 to 15 Percent Slopes <br />This map unit is associated with the gently to moderately sloping upland <br />benches. Vegetation consists primarily of crested wheatgrass, <br />cheatgrass, smooth brome, intermediate wheatgrass, Indian ricegrass, <br />sagebrush, and rabbitbrush. The upper horizons (A, B, C1) of this soil <br />unit were disturbed or salvaged during previous mining activity (i.e., <br />topsoil stockpiles, roads, and ahead-of-mining topsoil salvage). <br />Subsequently, five to eight inches of topsoil was replaced over light <br />yellowish-brown sandstone. This soil occupies 6.8 percent of the study <br />area (Table 9-4-3). <br />Chemical and physical properties for the replaced topsoil are suitable <br />(Tables 9-4-2 and 9-4-5). Coarse fragment contents typically range from <br />10 to 40 percent. Occasionally, the C1 horizon contains up to 65 <br />percent sandstone. Based upon ten profiles (Table 9-4-4), about seven <br />inches of suitable topsoil is available for salvage within Map Unit 7. <br />Map Unit 8 - Subsoiled Regraded Spoil, 2 to 15 Percent Slopes <br />This map unit is associated with the gently to moderately sloping upland <br />• benches, ridgetops, and sideslopes. Vegetation consists primarily of <br />9-4-24 Revised 11/01/86 <br />