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<br />2-182 <br /> <br />2.6 Soils <br />The soils descriptions, identifications, and locations provided for the 1981 Trapper Mine permit <br />document, as shown on Map 29 and discussed in this section, were determined by an order 1 Soil <br />Survey of the proposed mine plan area in the Summer of 1979 by Western Ecological Services Company. <br />An Order I soil survey was performed on the 795.71 acre Trapper Permit PR-7 Mine Expansion Area in <br />2014 to satisfy the requirements of Rule 2.04.9 of the Regulations of the Colorado Mined land <br />Reclamation Board for Coal Mining (Map 29A). The Natural Resources Conservation Service (NRCS) <br />published a soil survey report for Moffat County in 2004 titled Soil Survey of Moffat County Area, <br />Colorado. The NRCS soil survey was completed as a high intensity Order II survey. The 2014 survey of the <br />PR-7 Mine Expansion Area relies on the soil classifications of the 2004 NRCS report and, due to the <br />addition of new soil nomenclature, soil types for the PR-7 area do not match previous soil types <br />identified for areas to the west as part of the 1981 permit document (see letter from Darrell Schroeder <br />dated January 14, 1986, pages 2-184a and b of the Trapper permit document). Information on the soils <br />in the PR-7 Mine Expansion Area as well as a discussion of the testing completed for the soils is <br />contained in Section 2.6.3. <br />Soils were mapped at an Order I level for the 137.08 acres within the PR-11 mine expansion area in <br />2021. Section 2.6.4 details this mapping effort. <br />The principal geologic units that occur in the proposed mine plan area and that have influenced soil <br />development are the three most common ones of the Mesaverde group, i.e. the Lewis Shale, the <br />Williams Fork Formation and the Iles Formation, all of which are Cretaceous (refer to Section 2.7.1). <br />The Lewis Shale is composed of dark gray homogenous marine shale which lies unconformably on top of <br />the Williams Fork Formation. It is located in the north-western portion of the proposed mine plan area. <br />The Williams Fork Formation is composed of light brown to white sandstone, gray shale and coal beds. It <br />is the upper bedrock unit of the Mesaverde Group and occurs in the southern and eastern portion of the <br />proposed mine plan area. The Iles Formation is the older of the two formations comprising the <br />Mesaverde Group and is lithologically similar to the Williams Fork Formation. It occurs in the <br />southwestern corner of the proposed mine plan area. <br />Aeolian (wind-blown) material is a significant factor in terms of quaternary geology as it imparts a finer <br />texture to the soils in the study area. <br />Areas of glacial erratics were also noted on knolls within the survey boundaries, but their aerial <br />distribution was too small to be mapped out. <br />2.6.1 Soil Features <br />Most of the soils developed in the proposed permit area are deep (40 to 60 inches) and develop from <br />colluvium and some alluvium derived from interbedded sandstone. Effective soil rooting depths, in the <br />western portion of the proposed