Laserfiche WebLink
infiltration, and greatest water holding capacity on reclaimed spoil in Wyoming. Pinchak <br /> et al. (1985) also found 15 inches of topsoil to be optimum in Wyoming in terms of seeded <br /> species production and limited infestation of non-seeded species. Barth and Martin (1981) <br /> showed fine sandy loam topsoil depths to be 10 inches for optimum perennial grass <br /> production on nonsaline, nonsodic silt loam spoil in southeastern Montana. In <br /> northwestern Colorado, McCinnies and Nicholas (1982) demonstrated with field and <br /> greenhouse studies that vegetation stands, herbage yield, and root production all <br /> increased linearly as topsoil depths increased from 0 to 18 inches. <br /> DePuit (1984) points out that optimum plant community composition and diversity is often <br /> reached at shallower topsoil depths than what is required for maximum production. This <br /> phenomenon apparently exists at the Seneca and Trapper Mines. Pfannenstiel and Wendt <br /> (1985) demonstrated that six to eight inches of topsoil applied to Wadge spoil at Seneca <br /> Mine in 1976 has produced a native looking sagebrush grassland community with a shrub <br /> density of 1,450 stems per acre. Redente and Hargis (1985) demonstrated at Trapper Mine <br /> that with the compromise of some above ground production, performance of more life forms <br /> was maximized by replacing only six inches of topsoil. <br /> • <br /> Topsoil replacement depths at Nucla Mine will be adjusted by both mine area and the <br /> proposed post-mine land use. Mean topsoil replacement depths will be 10 inches for <br /> rangeland post-mine land use reclamation areas (north of County Road 124A-A and east of <br /> County Road 2650, west half of the new facilities area, north of and including the <br /> temporary by-pass road, and new disturbance areas within Mining Areas 2 and 3), 6 inches <br /> for the reclaimed portions of Mining Areas 2 and 3 (a 4 to 8 inch replacement depth was <br /> approved under Permit 75-36) and 15 inches for the dryland pasture post-mine land use <br /> reclamation areas (north of County Road 124A-A to the temporary by-pass road and west of <br /> County Road 2650). Mean suitable subsoil, spoil, excess topsoil, or topsoil substitute <br /> replacement depths will be 10 inches for the pre-law facilities area, pre-law shop area, <br /> pre-law spoil piles/pits associated with Mine Area 4, NPDES sites, explosive storage area, <br /> and associated access roads. Mine Areas 1 and 4 currently have 22.9 acre feet of excess <br /> topsoil whereas Mine Areas 2 and 3 have a topsoil deficit of 7.4 acre feet. Therefore, <br /> 7.4 acre feet of topsoil will be transported from Mine Areas 1 and 4 to Mine Areas 2 and <br /> 3. The current excess topsoil volume for the entire Nucla Mine is 15.5 acre feet. The <br /> • individual soil replacement categories are shown by mine area on Exhibit 21-2, Postmine <br /> Soil Replacement Depths. <br /> 21-16 Revised 08/19/88 <br />