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<br />32 <br />steepness of their footprint azeas, appear to constitute Valley Fills, subject to the more <br />stringent requirements of Rule 4.09.2. Volumetric calculations for the mined overburden <br />and proposed fills are presented in Exhibit #16. A preliminary tabulation of proposed fill <br />characterization, prepared by CTLJThompson, Inc., is presented within Table A on page <br />4 of Exhibit #13. A preliminary generalized sensitivity-style stability analysis, performed <br />parametrically for typical low and high fill sections and various assumed material <br />strengths, is summarized within Exhibit #13. <br />Examination of the permit application documents have discerned an apparent <br />inconsistency in regard to the specific relationship of the proposed fills, the lowermost <br />surface mined coal seam, and the backfilled spoil within the mined area. The text <br />descriptions included within the "2.05.3(2) Operations Description -First Permit Term" <br />section of the application suggest that the 21 proposed fills will be constructed below the <br />elevation of the lowermost surface mined coal seam, as is the case for the traditional head <br />of hollow fill. However, the cross sections included within the "2.05.4 Reclamation Plan <br />... Backfilling and Grading" section of the text (Figures 2.05.4-1 through 2.05.4-14) depict <br />many of the fill tops higher in elevation than the adjacent backfilled spoil. The top of Fill <br />#4, for example, is depicted on Figures 2.05.4-8 and 2.05.4-9 as being approximately 170 <br />feet above the adjacent lowermost extracted seam. This is in significant disagreement <br />with the generalized (spoil/clay soiVbedrock) fill sections analyzed within Exhibit # 13 and <br />represented as typical of the proposed spoil fill structures. Founding these fill structures <br />partially on spoil abutments might significantly affect the material pazameters and cross <br />sectional configurations used within the stability analyses. <br />In order to resolve these apparent inconsistencies the application should be revised to <br />clarify the relationship of the proposed fills and the lowermost mined seam and <br />superimposed backfill. This clarification might be aided by a simplification of the seam <br />naming conventions used throughout the text, cross sections and maps in the permit <br />application. Clazification of what specific coal seam is depicted as "COAL" on figures <br />2.05.4-1 through 2.05.4-14 would assist the reviewer. In addition a clear discussion of <br />specifically what seams will be extracted in the surface mine and the relationship of the <br />Isopleth Seam maps and the surface mining plan would be helpful. The necessary <br />information appeazs to be available but it is not integrated in a readily understandable <br />format. <br />Overburden Calculations (Exhibit #16) <br />Based upon the calculations provided within Exhibit #16, the initial six-year surface <br />mining plan depicted on Map 2.05.4-1 projects the excavation of approximately 46 million <br />bulked cubic yards of overburden above the Ciruela Coal Seam. Approximately 15 <br />million cubic yards o1'this material is projected to be placed within the nine preliminarily <br />proposed head of hollow (valley) fills adjacent to that mined area, leaving 31 million <br />cubic yards to be backfilled within the boundaries of the Mountain Top Removal mined <br />area. <br />