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be restricted to the channel and immediately adjacent areas, with a very steep and rapid transition <br /> to uplands. Mining will, therefore, occur adjacent to the creek drainage. A variable excavation <br /> buffer will leave enough elevation and distance to not disturb the creek channel and associated <br /> wetlands and minimize flooding of the pit floor during periods when the creek flows. <br /> Unlike most rivers and streams along the Front Range of Colorado, very little or no alluvial sand <br /> and gravel deposits are associated with the Lone Tree Creek channel. However, in some areas, <br /> the terrace deposits occur right up to the high and steep embankment of the incised creek <br /> channel. In these upland areas, aggregate will be excavated from the embankment, lowering the <br /> adjacent land surface to match the depth of the pit floor without disturbing the creek channel (see <br /> Exhibit C-5, Pre-Mining/Mining Plan Map). <br /> Earth Moving <br /> Areas to be mined are prepared by removal of topsoil and overburden. Each preparation area <br /> may be as much as 100 feet wide. Usually, only enough area is stripped and prepared to provide <br /> the estimated needs for the next 10 to 14 months of mining. Where it is found, surface topsoil <br /> material will be stripped separate from the underlying, deeper subsoil or overburden material. <br /> This topsoil layer contains most of the soils organic matter and will be stockpiled separately for <br /> use in reclamation. Once the surface layer has been removed, the rest of the overburden will be <br /> stripped and stockpiled separate from the surface layer. <br /> The active mining face will extend no more than 1,000 feet in length. During mining and prior <br /> to reclamation, the mine walls will be a nearly vertical to 1/zH:IV slope (see Exhibit C-5, Pre- <br /> Mining/Mining Plan Map). Mining will progress down to the depth of quality aggregate material <br /> or 8 to 12 feet below the surface. As the mining face progresses, pit sidewalls behind the mining <br /> activities will be reclaimed. So reclamation activities do not interfere with mining operations, pit <br /> sidewalls may extend 500 feet behind the active mining face without being reclaimed. The <br /> aggregate material will be recovered using equipment typical for sand and gravel mining <br /> operations. Earth moving equipment may include, but are not limited to dozers, loaders, <br /> scrapers, and excavators. The aggregate material from the pit will be temporarily stockpiled <br /> within the pit or transported directly off-site for processing. During mining and reclamation <br /> activities, watering trucks for dust control will be used as needed. <br /> Setbacks from the mine pit top of slope to the proposed permit boundary will be 50 feet or <br /> greater. Setbacks from near vertical mining excavations to the permit boundary will be a <br /> minimum of three times the adjacent pit depth to mitigate stability risks. Setbacks will also be <br /> maintained for potential side slope reclamation if"cut and fill" sloping is required, as discussed <br /> further in Exhibit E, Reclamation Plan. The need for "cut and fill' reclamation will be <br /> determined during the mining operation once overburden quantities and general pit depths are <br /> verified. <br /> Topsoil and overburden material excavated from the pit will be stockpiled and used for <br /> backfilling mine pit slopes and other reclamation activities. The non-marketable material <br /> stockpiles will be created adjacent to the areas that will be backfilled, but not within the Lone <br /> Tree Creek drainage area susceptible to flooding. When sufficient material is available in the <br /> stockpile, the material will be backfilled into previously mined areas. <br /> Carr Pit East <br /> DRMS 112 Permit Application Page 7 <br />