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• Potential mining and related impacts on the surface water system include <br />the following: <br />o Temporary Increases in Runoff for Surface Disturbance Areas <br />o Minor Reductions in Surface Flows Due to Operation of <br />Sedimentation Structures <br />o Alteration of Surface flow Patterns <br />o Changes in Surface Water Chemistry <br />o Increases in Levels of TDS and Specific Chemical Constituents <br />Generally, probable surface water hydrologic consequences resulting from <br />EFCI's mining operations will be limited by the relatively small surface <br />disturbance area, and will be mitigated by operation of the drainage and <br />sediment control system and ultimate reclamation of mine disturbance. <br />Probable surface water impacts and their significance relative to the <br />hydrologic system are discussed in the following sections. <br />• In conjunction with construction/installation of mine facilities, <br />excavation and development of the mine portals, ongoing coal refuse <br />disposal operations, and construction of the coal loadout, EFCI has <br />disturbed approximately 105 acres of surface area. Disturbance has <br />involved removal of vegetation and topsoil materials and grading of <br />disturbance areas for specific mine related uses. Removal of topsoil and <br />vegetation results in conditions which tend to increase surface runoff <br />and reduce moisture infiltration. Resulting increased surface runoff <br />volumes enter the surface drainage system increasing both peak and overall <br />flow volumes. <br />In order to control increased runoff from disturbance areas, EFCI diverts <br />runoff from undisturbed up-gradient areas around the area of mining <br />disturbance, grades disturbance areas to minimize runoff and erosion, and <br />collects runoff as close as possible to its source and routes it to <br />sedimentation ponds for retention. In addition, EFCI controls discharge <br />• from sedimentation ponds to approximate normal streamflow conditions and <br />utilizes localized erosion control measures where appropriate to control <br />runoff flow velocities, reduce runoff sediment levels, and limit erosion. <br />2.05.6-47 <br />