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• Colorado, Mcginnies and Nicholas, 1982, demonstrated with field and greenhouse studies that vegetation <br />stands, herbage yield, and root production all increased linearty as topsail depths increased from 0 to 1.5 <br />feet. BaRh (1984) found that production of perennial grasses on bare spoil with no adverse properties, was <br />as great as when spoil was covered with soil of any thickness. <br />DePuit, t984, poiMS out that plant community composition and diversity for rangeland is often reached at <br />shallower topsoil depths than what is required for maximum production. This phenomenon apparently exists <br />at the Senece Mine in northwestern Colorado where Pfannensfiel and Wendt (1985) demonstratetl that 0.5 <br />feet of topsoil applied to Wedge spoil in 1976 has produced a native looking sagebrush grassland community <br />with a shrub density of 1,450 stems/acre. Proper topsoil handling techniques used in combination with <br />suitable spoil replacement and topsoiVspoil scarification, where needed to reduce compad'wn, are mot <br />effective in reestablishing minesoil productivity than 50 yeah; of succession on poor quality minesoils <br />(Schafer et al., 1979). <br />A mean topsoil replacement depth of approximatety 1.3 feet over final graded spoils at Seneca 11-W Mine <br />(North area) will be beneficial to establishing a good seedbed and rooting medium. This conclusion is <br />supported by the above referenced literature, premine soil survey (fob 9), and vegetation inventories (fob <br />10), as weft as ort-site data from the Seneca V Mine. The anticipated loamy topsail texture will likely have <br />favorable infiltration and water holding charaderisUcs. Also, the spoil medium immediately below the topsoil <br />• will typically have desirable chemical and physical characteristics far plant growth induding a loamy texture, <br />low sodiciiy and salinity, and moderaiety low saturation percentage for acceptable water holding <br />characteristics, and no minor element toxicity problems (see Tab B, Geology and Overburden Assessment). <br />SCC hoe revised the approved traditional approach for topsoil replacement n the II-W South <br />area, based on requests made by the Division. For the II-W North Areas (original permit <br />area), where soil replacement has been completed, the approved 1.3 foot (L5.6") average <br />replacement thickness is still applicable, and is indicated on Exhibit 21-L The 2005 Annual <br />Reclamation Report updated topsoil balance indicates that there is sufficient topsoil ro <br />replace 1.1 feet over the entire remaining disturbance area. This updated topsoil balance <br />indicates that applying 4 feet of soil in the remaining aspen plot and 0.6 feet over the upland <br />shrub areas, there should be sufficient topsoil to apply a "standard average replacement <br />thickness" of 1.1 feet over the remainder of the graded areas. Within the "standard 1.1 foot <br />ave~aQe replacement thickness areas, the minimum thiclmess in any particulaz location will <br />be 9 inches. <br />Maintenance and Tesfina Procedures. Prior to distribution of topsoil in the Lennox coal outcrop sampling <br />area shown on Exhibit 6-6, final graded areas {on which topsoil is to be applied) will lie sampled to confirm <br />spoil suitability (see Tab 21, OverburdeNSpoil Handling Plan for more details). The tlensity and physkal <br />characteristics of the replaced topsoil and upper spoil will be observed. Past experience at Peabody's <br />. Seneca 11 Mine has shown that scarifying all spoil roads will correct the signfignt compaction problems. <br />PROS 31 Revised 4106 <br />