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overlies the Trinidad Sandstone, a slight increase in the dissolved solids in <br />• the recharge from this small area will have minimal impact on the quality of <br /> water in the Trinidad Sandstone. Establishment of a soil and vegetation cover <br /> comparable to the premising condition should be sufficient to minimize the <br /> adverse impacts of mining on groundwater resources in the mine area and <br /> adjacent area. <br />2.05.6.3.2 SURFACE WATER <br />A) Introduction <br />The proposed Rlmrock Mine operation will have no significant <br />Impacts to the surface water hydrology of the area. This is due <br />to a number of reasons, all of which will be discussed in this <br />section. Also, specific concerns such as caster from underground <br />mine workings, spill prevention and containment and other items <br />will also be discussed. <br />B) Water Duantity and ouality Imoacta to Engleville Oulch <br />' Up to She point that the Engleville ouich leaves the mine <br />disturbed area, the total drainage for the gulch is approximately <br />1464 acres. This acreage is sparsely vegetated with steep slopes <br />and poor soils. Runoff is high and sediment loads ar• high during <br />significant summer rainfall events. The average curve number for <br />the drainage ores is 75. <br />The proposed Rlmrock Mine disturbed area flowing to the sediment <br />pond is only 21.15 acres over the life of the mine. Ths estimated <br />curve number for this area is 83 to 86. At any given time during <br />the permit, the disturbed acreage should bs well below this <br />total. The total disturbed screage is only 1.411 of the entire <br />drainage area. An insignificant acreage for the topsoil stockpile <br />will contain its own sediment control berm and sump. This small <br />amount of disturbed area relative to the Engleville Oulch <br />drainage eras should result in a very minor impact, even when the <br />sediment pond is not considered. <br />Section 2.04.7.2 describes the existing water quality end <br />quantity in Engleville Gulch. Analysis results are given in <br />Appendix '4. Overall, the snelyais shows that no parameters are <br />above EPAllimits, however, suspended solids can be high during <br />swift runoff events. <br />The mine operation will install a sediment pond to detain the <br />• runoff from the disturbed acreage (19.78 acres) and also soma <br />undisturbed area above the minesits (17.45 acres). Th1• pond will <br />provide 24 hour detention time for all storms below the 10 year - <br />-3- <br />