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in the stream bed gravel, thus accounting for the extra zinc seen downstream. There are no other <br />visible locations along the permit area where water is entering Sneffels Creek that could be elevating <br />the zinc levels downstream. Also, the Atlas drainage is so high in zinc compared to all other sample <br />points that it would not take much flow there to account for the difference. A further detailed <br />discussion about the zinc levels at the Revenue Mine can be found in subsection 1.1 of Exhibit T. <br />4.4 Surface Water Systems Designs for Mine Operation <br />Surface water runoff at the Revenue Mine that passes over disturbed areas will be controlled by a <br />series of collection ditches and sediment ponds. This will prevent sediment generated by storm events <br />from leaving the mine site and negatively affecting Sneffels Creek. The stormwater basins, ditch <br />structures, culverts, and sediment ponds can be seen on Map G -1. Table G -6 shows the rainfall <br />amounts of the storm events in the Revenue area.Table G -7 shows the sediment pond capacity versus <br />the stormwater basin runoff amounts. Diversion ditches will be used to divert undisturbed runoff from <br />the two mines disturbed areas: the main Revenue disturbance and the Atlas Pile disturbance, which are <br />separated by the Atlas drainage. Appendix 6 contains all of the detailed calculations and designs for all <br />of the stormwater basins (SWB), collection ditches, diversion ditches, culverts, and sediment ponds at <br />Revenue Mine. <br />Stormwater runoff that flows from uphill of the mine will be redirected around the mine disturbance <br />via diversion structures to the existing drainages that feed Sneffels Creek. Map G -1 shows the area <br />drainage basins that impact the Revenue Mine, along with the diversion ditches. Map G-1B shows the <br />drainage basins on the disturbed portions of the site during the worst case of mining. The biggest <br />drainage from uphill of the Revenue Mine, known as the Atlas Drainage, will be avoided by mining <br />operations. Diversion ditches are all designed to convey the 100 -YR 24 -HR event without generating <br />sediment. The detailed runoff and peak discharge calculations along with the ditch designs were <br />calculated using Carlson and AutoCAD software. <br />The basis of the design is the following: <br />Revenue Mine August 2012 G -18 <br />