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MLE2 also will develop the ECOSA in the middle reaches of Grassy Valley. The ECOSA will <br />manage and capture snowmelt and precipitation runoff during operation to prevent erosion and <br />sediment transport. The snowmelt or precipitation during operation will infiltrate the ECOSA <br />and will be captured by the Diatreme drainage system. This is likely to reduce surface flows at <br />GV -03 during operation. After closure, the ECOSA cover system will manage runoff to <br />minimize erosion and sediment transport. The runoff volumes will be similar to pre -ECOSA <br />conditions in the footprint. The snowmelt or precipitation that infiltrates the ECOSA cover <br />system will be captured by the Diatreme drainage system, similar to the pre -ECOSA conditions. <br />The runoff and infiltration conditions for the closed ECOSA facility therefore are likely to have a <br />neutral effect on surface flows at GV -03 after closure. <br />MLE2 will develop the SGVLF in the middle reaches of the Squaw Gulch drainage. The <br />SGVLF will cover approximately 346 acres with impermeable liner. The SGVLF will capture <br />precipitation and is therefore likely to reduce surface runoff and flows in lower reaches of the <br />Squaw Gulch drainage. Periodic flow at SG -10 is expected to continue due to snow melt and <br />runoff in the spring and from precipitation and runoff in the summer and fall in the lower reaches <br />of the Squaw Gulch drainage; however the quantity of water is expected to be reduced. Based on <br />the water composition for SG -05, SG -07, and SG -10, the major water quality constituent <br />concentrations at SG -10 after the construction of the SGVLF are expected to be similar to the <br />current conditions. The removal of historic mine features and other materials during <br />construction of the SGVLF in the middle reaches of Squaw Gulch may decrease the <br />concentration of trace metals (e.g., aluminum, manganese, nickel, and zinc) at SG -10. <br />The capture of precipitation by the SGVLF will limit infiltration of precipitation to, and <br />saturation of the shallow alluvium in the middle reaches of the Squaw Gulch drainage. The <br />drainage of ground water in the shallow alluvium in the middle and lower reaches of Squaw <br />Gulch into the granite bedrock and into the Diatreme will continue after construction of the <br />SGVLF. Water quality conditions in the shallow alluvium and bedrock after the construction of <br />the SGVLF are expected to be similar to the current conditions in the near -term. The selective <br />removal or stabilization of historic mine facilities in the middle reaches of Squaw Gulch during <br />SGVLF development also is likely to improve the ground water quality in the long -term. <br />The implementation of MLE2 will have little or no impact on the surface and ground water <br />conditions in Cripple Creek, Poverty Gulch, Gold Run, Wilson Creek, and Vindicator Valley. <br />'Cripple Creek & Victor Gold Mining Company <br />Cresson Project Hydrologic Evaluation for Mine Life Extension 2 <br />41 <br />