2008-06-09_REVISION - C1980007 (3)

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Soils • C: • Table 3-2 Summary of Soil Resources of - Hazard it Name / il M U S Soil Map Unit Dominant Depth ap n o 1\~ame / 1\rumber Soil Series Map Class water Shrink Mass Number Unit Erosion Swell Movement Papaspila soils. Taterheap and 50 VD H M L - M Steep slopes; high soil Taterheap -Papaspila similar soils erosion hazard; moderate complex, mass movement potential in 40 to 65 percent the steeper areas; moderately slopes Papaspila and 35 VD H L L - M slow permeability. 189 similar soils Subsurface rock fragments in Papaspila soils. Wetopa soil and 50 VD L - H H L - H Slow permeability; high similar soils erosion hazard and mass Wetopa -Wesdy movement potential on steep Complex, slopes; shrink-swell 5-65 percent slopes Wesdy and 35 VD L - H M L - H potential. 200 similar soils Subsurface rock fragments in Wesdy soils. Depth Classes: S =Shallow; MD =Moderately lleep; ll = lleep; vl) =very lieep. nazara -caungs: L = l,uw; ivi - rvicwuiii, ~. - ~.,s... Source: Cryer and Hughes 1997. ~ Ventilation shaft would be constructed using a previously approved and constructed drill pad. Soils in the project area are generally deep, fine-textured and well suited for vegetative production with steep slopes being the primary limitation on use. Potential impacts on soil resources include soil loss during salvage and replacement, soil loss in stockpiles due to wind and water erosion, reduced biological activity and reduced soil structure. Soils on steeper slopes have slower infiltration rates, resulting in more surface flow and erosion. Mass movement on steep slopes is also potential hazard, with Wetopa and Wesdy soil types slopes have slower infiltration rates, resulting having the highest potential hazard rating in the project area. Fine textures and high activity clays result in moderate to high shrink-swell hazard ratings for most soil types. Analysis methods used for soils overestimates the amount of disturbance in each soil type because it incorporates broad road corridors and drill pad windows. This method captures anticipated disturbance which could occur in all possible soil types identified by road corridors and MDW buffers. The actual on-the- ground disturbance for a road in the corridor and an MDW in the window will be less than estimated with this method. Therefore, this analysis estimates the potential disturbance by soil type and is not representative of the actual acres that would be disturbed by the proposed action (Table 3-3). Table 3-3 reports the acreage of individual map units that would be disturbed by alternative. However, because the analysis assumes placement of roads and MDW locations in corridors or windows disturbed soil acreages shown in the table should be regarded as an over-estimate that would likely be reduced when road and drill pad locations were identified on the ground. Direct and Indirect Effects Alternative 1 No additional construction of drill pads or access roads, or the ventilation shaft / escape- way would occur and current management Deer Creek Ventilation Shaft and E Seain Methane Drainage Wells FEIS 75