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movement) may result. <br /> 3. if none of the above procedures satisfactorily mitigate a certain problem, the <br /> Division will be notified and recommended actions will then be implemented. <br /> Peabody will maintain and periodically review the existing quality control program used to <br /> evaluate overburden, interburden, and spoil handling activities at Nucla Mine. Peabody <br /> will maintain records of the sampling results for each logical reclamation unit. These <br /> records will be kept on file at the mine site or Division office and will be reported <br /> within the Topsoil Balance/Spoil Quality Report to be submitted annually on April 15 of <br /> each year. <br /> Nucla East Compactibility and Erodibility. Determining the compaction potential of <br /> disturbed overburden is important to assess postmine spoil conditions including: <br /> hydraulic conductivity, revegetation success, landscape stability, and equipment <br /> trafficability. Generally, stability and/or compaction problems are related to soils high <br /> in shrink/swell clays, soils with large proportions of sand and clay (sandy clay- texture), <br /> and soils with approximately equal proportions of the sand, silt, and clay-size particle <br /> fractions (Arnold, 1977). These three conditions are not highly desirable since a high <br /> shrink/swell clay content in postmine landscapes causes poor stability and low <br /> permeability conditions, a sandy clay textured soil develops surface crusting problems, <br /> and an equal particle-size distribution causes excessive compaction which results in <br /> restricted water movement and root growth. <br /> The first two considerations listed above were among those used for establishing the <br /> grading system for texture. Unsuitable clay textures were identified within two thin <br /> lenses of the upper overburden in the western half of the study area (Tab 6, Attachment <br /> 6-1 ). These clay lenses occur only in the extreme western part of the Nucla East permit <br /> area near overburden Drill Site 870E (see Exhibit 6-7, Geologic Cross Section and Sample <br /> Locations for Nucla East Study Area). These increments are not currently in the projected <br /> mining disturbance area (see Exhibit 12-3, Operations Plan - Nucla East). No sandy clay <br /> textures were identified within the Nucla East Study Area. <br /> The Nucla East postmine spoil textures will typically be loamy with an approximate <br /> particle size distribution of 65 percent sand, 25 percent silt, and 10 percent clay (Tab <br /> 6, Attachment 6-1 ). Surface crusting, which is critical to seedling emergence, is <br /> discussed in the Soil Survey (Tab 8), Revegetation Plan (Tab 22), and Topsoil Management <br /> 21-7 Revised 04/11/88 <br />