2011-09-19_REVISION - M1982155 (17)

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Materials Handling - Backfilling As available, overburden material will be used for backfilling. The pit floor will receive only enough backfill to create final grading for drainage and to establish a growth medium for revegetation. The pit slopes will require backfilling to achieve final reclaimed slopes of 3H:1V (see Exhibit F -3, Reclamation Plan Typical Sections). Because of the small pit size and potential depth of the deposit, it may not be possible to achieve complete side slope reclamation by backfilling with available overburden material. Although the overburden material is generally deep (4 to 6 feet) on the relatively flat pediment surface, the total area for overburden recovery is limited. Preliminary material balance estimates suggest that approximately 150,000 cubic yards of overburden material may be available, but the depth of the pit at possibly 30 to 50 feet and the desired reclamation slopes of 3H:1 V could require 150,000 cubic yards or more for reclamation. In addition to the side slopes, overburden material is also required to cover the pit floor for drainage grading and to establish a growth medium. The result is, depending upon the amount of overburden material recovered and available for reclamation, side slope backfilling may need to be enhanced with an initial "cut and fill" of the near vertical side slopes (see Exhibit F -3, Reclamation Plan Typical Sections). The degree of "cut and fill" required, if any, will be determined during mining as overburden material quantities and pit depths are realized. Materials Handling - Grading The 3H:1 V pit side slopes will be graded to transition into the relatively flat pit floor. Grading of the pit floor will leave a subtle rolling topography rather than a completely flat bottom. The variations in topography should not create water catchment areas, but should be graded to drain freely. The topography is intended to control water flow and create a variety of microenvironments so a wide variety of vegetation assemblages can develop. This form of final grading greatly improves the diversity of wildlife than can live on the area and also encourages some dynamic interaction between different vegetation forms. The side slopes will also not be graded smooth, but will contain a low profile ridging pattern that follows the contour. Final grading that leaves this type of ridging pattern helps to capture water for plant growth as well as reduce the velocity of runoff and slope erosion. On these slopes, erosion may present a maintenance issue for the first year or two of revegetation if there are large, drenching thunderstorms, but more normal low intensity thunderstorms should not create more than minor rilling if the grading ridges are done along the contour. Blending of the pit outlet is important to prevent pooling of water in the pit bottom and to avoid creating a steep slope at the pit edge that encourages erosion. The final grading of this transition area will blend the topographic contouring from the pit floor with the undisturbed topography beyond the pit edge. Topsoiling and Growth Media As is currently the case at the Fountain Pit, the growth medium will be a combination of overburden and topsoils. Unfortunately, there is not a large quantity of quality topsoil available at this site. The topsoil is only marginally different from the overburden, with its main Fountain Pit M- 1982 -155 DRMS 112 Permit Amendment Page 12