2007-01-31_REVISION - M1986015 (2)

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MINING PLAN define the pattern fairly well. There were some inconsistencies in the values derived from holes drilled near each other, but [hat was probably due more to interpretative differences than actual differences. Phase 2 tends to have a more uniform deposit than Phase l where the gravel thickness sometimes varies by as much as a factor of two. The drilling information does not show those kinds of variations in Phase 2, although there does appear to be slightly increased variability in the eastern portions near the Phase 1 boundary. This is not unexpected as the greatest variation in Phase I is in [he western portion near [he Phase 2 boundary. The cross-sections located at the end of this exhibit show a sampling of the variations across the site. Sections A and B are for Phase 1 while Sections C and D are for Phase 2 and Section E includes both phases in a west to east direction. The actual mining plan was prepared using many more cross-sections than are presented here. On some of the planning cross-sections the gravel layer was fairly consistent across the length of the section and the overburden declined rather evenly toward the river. But on other sections, primarily in Phase 1, the gravel layer varied widely indicating it was deposited on [op of a highly variable erosion surface. Probably these variations represent different depths of erosion by the river as it meandered back and forth across former erosion surfaces. This pattern is often seen in fairly swift flowing rivers like the Arkansas. Often the river depth on the outside of a meander bend is greater where cutting is more intense than near the inside of the bend where cutting is more gentle. Furthermore, the outside of the meander typically has a very steep channel slope while the channel slope on the inside of [he meander is usually more gradual. This asymmetry is evident when adjacent cross-sections are linked laterally. Variations from place to place can also occur because meander changes are not usually smooth or gradual. Instead, meander changes are often induced by major floods. If one could view the changes as if in a time lapse movie, the changes would make the river channel appear to jump around. As a result of [his "catastrophic" change pattern which often occurs in meandering rivers, gravel deposits can vary tremendously from place to place, both with respect to the quality of the material and [he depth and quantity of the material. Another cause for a highly variable bedrock resulting in variable depth could be [he existence of paleo-drainages that entered [he river valley before there was extensive filling with sediment. These drainages could have produced their own humps and hollows without any relationship to the original main river channel. After filling the valley with sediment these ancient erosion features can be expressed as locations where the current depth of [he deposited gravels are shallow or deep. Interestingly though, the current surface may not exhibit any features that would indicate variations in the depth of the deposit. Based on the cross-sectioning done in the planning of this gravel operation, it is suspected that considerable variation may be found in [he extent and quality of the gravel over such a large site. This variability mainly applies to Phase 1. In Phase 2 such variability in [he sub-gravel shale surface seems to be largely absent resulting in a fairly smooth sub-gravel topography. These variations are best seen in Pueblo East Pit Amendment 3 (2007) Exhibit D Page 10 of 34