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As described in detail in the Groundwater discussion which follows, the pit will not pump below <br />the water table, therefore no dischazge will occur. Gravel will be extracted in wet conditions <br />from the existing surface. <br />The three principal ways that the gravel pit could affect the water quality of the area downstream <br />aze: <br />al Through poor sediment control within the site causing increased sedimentation downstream <br />As described in the mining plan, water will not be dischazged from the site, so sedimentation <br />should not be a problem. In the event that one of the stockpile berms fail, there could be a <br />temporary minor release of sediment from the site but it would be very minor. Also, many of the <br />berms have been in place for years and there has never been the slightest issue with a slope <br />failure or other issue resulting in excess erosion. The berms will be seeded and planted if they aze <br />to remain in place for more than 6 months. <br />b) By fuel leakage from a ruptured tank or dispensing spillage <br />Fuel leakage is also not a problem since all fuel tanks on site will have secondary containment as <br />well as strict SPCC Plan procedures for spill prevention and control. <br />c) Increased selenium in the groundwater by mining on the top of the Mancos Shale. <br />As seen in the water data in Appendix A, selenium in the Uncompahgre River is approximately <br />0.5 µg/liter. The CDPHE determined that the level of selenium chronic to aquatic life is 4.6 <br />µg/liter. The acute level is 18.4 µg/liter. In azeas where the underlying Mancos Shale has high <br />selenium, the Division of Reclamation, Mining and Safety usually requires that a minimum of 2 <br />feet of gravel be left above the shale to avoid disrupting the shale and causing releases of <br />selenium. Since this operation will mine with a track hoe on the existing surface and the bottom <br />of the deposit is well below the reach of the hoe, a minimum of 5 feet of undisturbed gravel will <br />Colona Pit November 06 G-2 <br />