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• Mining Plan <br />1. Geology <br />Exhibit D <br />The site will mine a sand and gravel deposit which is an alluvium of the recent period of Quaternary <br />age. The alluvium is relatively shallow (less than 25 feet thick) and is underlain by the sandstones, <br />siltstones and mudstones of the Wasatch Formation. These sedimentary layers were formed when <br />uplifting Rocky Mountains to the east blocked eastward drainage during Tertiary time and the Uinta <br />Mountains blocked northward drainage and a very large lake formed in northwest Colorado, northeast <br />Utah and southwest Wyoming. This lake is referred to as Lake Uinta and it received all the washout <br />material from river floodplains and deltas from the mountains on all sides of the lake. Some of the later <br />mud which entered the lake became what is now the Green River Shale, which is noted for its oil <br />content. The Green River Shale forms the hills immediately south of the permit area. Lake Uinta lasted <br />for 6,500,000 years until further uplifts drained it. <br />• 2. General Mining Plan <br />The gravel zone is approximately 21 feet thick in an alluvial deposit and is overlain by topsoil which <br />averages 1.0 to 1.5 feet in thickness with approximately 2-8 feet of overburden until the gravel deposit <br />is reached. In the amendment area the overburden is expected to average 4 feet thick. Mining will take <br />place to a total depth averaging 25 feet. Higher overburden exists in the southeast corner of the <br />property, which will be part of the facilities area which will not be mined. Sand and gravel are the <br />products mined from this site. Topsoil and overburden are stripped in advance of mining with a track <br />hoe and truck. Gravel is mined out with a front end loader, and directly transported into a truck or the <br />crusher. In any mining phase that has a wetland footprint; material will be excavated via track hoe <br />directly into a haul truck. No temporary stockpile is created in any phase with wetland footprints. Any <br />stockpiling that does take place will be on the established processing site on the south side of the pit, or <br />in mining phases that are free of wetland footprints. <br />The topsoil piles will have slopes no greater than 3H:1 V. Overburden will also be removed and <br />stockpiled. Topsoil and overburden will be stockpiled separately but both material stockpiles will be <br />• <br />White River City Pit, August 08 D-1