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• crusting problems, and an equal particle-size distribution causes excessive compaction which results in restricted water movement and root growth. The first two considerations listed above were among those used for establishing the grading system for texture. Unsuitable clay textures were identified within two thin lenses of the upper overburden in the western half of the study area (Section 2.04.6). These clay lenses occur only near overburden Drill Site 870E (see Map 2.04.6-1, Geologic Cross Section and Sample Locations for New Horizon 2 Study Area). These clay lenses are in the projected mining disturbance area and when they are being excavated, they will be thoroughly mixed with non clay type overburden. The mixing and dillution process will be accomplished by: 1) blasting, which will start the mixing of clay lenses with non clay formations above and below the clay seam 2) the overburden shovel wit be digging a full face through the clay tense from top to bottom to load each truck for transportation to the backfill, 3) and finally, the trucks with the diluted clay lenses on board will dump their load along a several hundred foot dump face. After this process, the concentration in any one spot of clay like material will be minimal and compatibility of the backfill will be negligible. • The New Horizon 2 postmine spoil textures will typically be loamy with an approximate particle size distribution of 65 percent sand, 25 percent silt, and 10 percent clay (Section 2.04.6, Geology Description). Surface crusting, which is critical to seedling emergence, is discussed in the Soil Survey (Section 2.04.9), Revegetation Plan (Section 2.05.4(2)(e)), and Topsoil Management of this Section. Since clay percentages and shrink-swell potentials are low, stability and traffcability problems are not anticipated. Prior to topsoil replacement, the regraded spoil within mined areas will be scarified by deep ripping or chisel plowing on the contour to a depth of 12 to 24 inches to reduce excessive compaction, prevent potential slippage zones, reduce erosion, and improve water and air movement and root growth across the topsoil/spoil interface. Abandoned roads shall also be ripped and/or chisel plowed prior to topsoil replacement. Spoil erodibility is discussed in the Backfilling and Grading (Section 2.05.4(2)(c)) and Facilities (Section 2.05.3) sections. Soil and topsoil erodibility is discussed in the Soil Survey (Section 2.04.9) and the Revegetation (Section 2.05.4(2)(e)) sections. • (Revised 24 AUG 06) 2.05.4(2)(d)-8