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• The three principal ways that the gravel pit could affect the water quality of the azea downstream <br />aze a) through poor sediment control within the site causing increased sedimentation <br />downstream, b) by fuel leakage from a ruptured tank, and c) increased selenium in the dischazge <br />by mining on the top of the Mancos Shale. As described in the mining plan, the sediment pond <br />and sump will be designed for optimal sediment control. Fuel leakage is also not a problem <br />since all fuel tanks on site will have secondary containment as well as strict SPCC Plan <br />procedures for spill prevention and control. As seen in the water data in Appendix B, selenium <br />in the North Fork of the Gunnison River runs at approximately 4.0 µg/liter. The CDPHE <br />determined that the level of selenium chronic to aquatic life is 4.6 µg/liter. The acute level is <br />18.4 µg/liter. <br />According to seazches on the Division of Water Resources database, there is only one well which <br />is within 600 feet of the Anderson Pit. This is a gravel well permit for the Fredlund Pit. There is <br />another well which is outside of the 600 foot offset from the mining boundary, so it has not been <br />shown on the map. There aze no stock ponds or springs within a reasonable distance of the <br />• Anderson Pit. As a part of the Gravel Well Permit filed with the Division of Water Resources, <br />well release forms have been obtained from both well owners, although the second well is in <br />excess of 600 feet of the Anderson Pit. <br />In order to allow dischazges of water from the site as is proposed in the Mining Plan, a combined <br />storm water/process water NPDES permit has been obtained from the CDPHE. <br />2. Groundwater <br />The site will mine an alluvial sand and gravel deposit from the recent period of Quaternary age <br />formed on a bend of the Gunnison River. The alluvium is relatively shallow (less than forty feet <br />thick) and is underlain by Mancos Shale. The River itself is actually cutting in the Morrison <br />Formation, which is also known for its purple and green shales. Rising immediately from the <br />west bank of the river and also located 1000 feet further to the east are the resistant reddish <br />sandstones of the Dakota Sandstone Formation. These sandstones form many of the red <br />I• <br />Anderson Pit, Apri107 G-2 <br />