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. 1.4.1.3 Impoundment Rearadinc <br />Calculation of regrade times for existing and future impoundments is shown in Table 1.4-6. Impound- <br />ment volume calculations are shown in Table A-3 of Appendix A. <br />The earthen impoundments would be graded with dozers, filling back the areas from which the material <br />had been previously removed, Caterpillar D10R dozers with asemi-u blade were used to develop cost <br />data and productivity. This regrading would establish the approximate original contours in the affected <br />areas. <br />1.4.2 Retonsoilina <br />After regrading, topsoil from permanent stockpiles would be placed on all disturbed areas except for such <br />minor disturbances as light duty access roads where topsoil was never removed. Topsoil replacement <br />costs are summarized in Table 1.4-8 while Table 1.4-9 summarizes re-topsoil quantities and time. <br />Productivity and cost values were those of Caterpillar 637E scrapers. This equipment type and particular <br />model was selected as a cost efficient means of loading, transporting, and uniformly spreading the top- <br />soil. <br />• The areas requiring topsoil replacement would inctude all active, inactive and abandoned pits and their <br />associated roadways, impoundments, and the industrial complex area. These areas were calculated in <br />the following manner. <br />Map M106 illustrates topsoil removal and replacement activities for each year of the permit term, <br />including the worst case year of 2004. This map is the basis for pit disturbance areas. The industdal <br />complex area and other topsoil replacement areas were calculated from mine work maps. <br />1-41 <br />