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• EFCI sedimentation ponds will intercept and temporarily retain runoff from <br />contributing disturbed drainage areas. The total volume of runoff <br />retained will not be significant relative to total drainage quantity for <br />area watersheds. Given the fact that ephemeral drainages in the area <br />typically flow only in response to snowmelt and major storm events, the <br />sedimentation structures will, in addition to providing sediment control, <br />function as localized flood control devices. In this capacity, these <br />structures offer the potential advantage of extending flow intervals for <br />downstream drainages. Operation of the Southfield sedimentation ponds <br />will not effect downstream water rights since dry streambed conditions on <br />Newlin Creek limit the surface hydrologic connection. <br />In order to insure compliance with applicable water rights and use <br />agreements, EFCI maintains comprehensive records on groundwater inflows <br />to the mine, use from the Corley Mine Well, and discharge quantities, and <br />calculates runoff contributions to the sedimentation structures, and <br />• water lost through evaporation. These components are utilized to <br />determine an annual water balance which is provided to the CMLRD as part <br />of the Southfield Mine Annual Hydrology Report. This water balance <br />effectively documents an annual consumptive use for the mine of <br />approximately 35.6 acre/feet. Through continuous monitoring and review, <br />EFCI makes necessary adjustments to ensure that this water balance is <br />maintained. Additional discussions relative to water rights and use are <br />presented in Section 2.04.1, Hydrology Description, and Section 4.05.15, <br />Hydrologic Balance - Water Rights and Replacement. <br />Protection of Surface and Groundwater Oualitv. Surface water quality in <br />the mine and loadout areas may be impacted by the following specific <br />activities: <br />o Removal of Vegetation and Topsoil from Disturbance Areas <br />o Surface Placement of Coal Refuse Materials <br />o Mine Dewatering <br />. o Coal Preparation Activities <br />o Coal Storage and Handling <br />o Operation of Drainage and Sediment Control Structures <br />2.05.6-15 <br />