Laserfiche WebLink
• <br />Mountain Coal Company Exhibit 27 <br />West Elk Mine Characteristics of West Elk Mine Soil lvtapping Units <br />Extent and Maior Areas of Occurrence - Mapping unit number 16 occurs in small <br />acreage in the West Elk sntdy area and is found principally on the terraces and vallev <br />tilling sideslopes east of Minnesota Creek and nor[h of its east fork. <br />Characteristic Tooo~raohv - Soils of this mapping unit occupy gently to moderately <br />sloping stream terraces and the lower ends of alluvial fans and valley filling sideslopes. <br />Slopes are uniform. ranging from about two percent to ten percent. <br />Physical Pro~rties -The soils of mapping unit number 16 are mature soils with distinct <br />horizonation and well developed. stable natural soil structure. This soil structure is <br />essential to the movement of air and water through the soil and to the penetration of plant <br />roots. With proper management it can be presen•ed and at least partially recreated even <br />if the soil is disturbed. The soils of mapping unit number 16 are good sources for <br />seedbed material. <br />• <br />The soils of this mapping unit are medium to moderately fine textured and are subject <br />to packing if continuously traversed by heavy machinery. They can be handled over a <br />moderate range of soil moisture without serious toss of favorable properties; however, <br />they can be irreversibly puddled if handled when too wet. Thus while physical damage <br />can be done by improper handling methods, the danger is not as great as in finer textured <br />soils or soils with little or no structure. <br />These soils have moderate shrink/swell ratios. Coefficients of linear extensibility range <br />from 0.2 to 0.05 and total potential expansion of a 40 inch thickness ranges from 0.8 to <br />2.0 inches. <br />Normally, the soils of this unit are not subject to serious flood hazards although a few <br />areas immediately adjacent to permanent streams may flood occasionally. In their natural <br />state they are not susceptible to much accelerated erosion unless native vegetative cover <br />has been destroyed or seriously depleted. When disturbed and cleared they are <br />moderately susceptible to both wind and water erosion and should be managed with <br />appropriate control measures. <br />No tendency toward mass movement is noted within areas mapped as unit number l6 and <br />the potential for such movement is low. <br />• <br />Chemical Properties and Natural Fertility - These soils are moderately weathered and <br />maturely developed, having distinct genetic horizonation including horizons of secondary <br />carbonate accumulation. The soil exchange complex is dominated by calcium; however, <br />not enough free carbonate from magnesium and calcium is present to tie up plant <br />nutrients. As a result, the soils are neutral to alkaline. <br />Exhibit 27-I1 <br />