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2.05.6(3) Protection of Hydrological Balance <br />• The Rockcastle Company has planned its mining operation to <br />minimize disturbances to the existing hydrologic balance. The most <br />important method for doing this is through a series of diversion ditches <br />and sedimentation ponds as shown on the Mining Plan Map. The sedimenta- <br />tion ponds have been sized to capture sediment contained in runoff from <br />disturbed areas resulting from a 10 year 24 hour precipitation event. <br />Calculations showing watershed areas and resulting size requirements for <br />the sediment ponds are shown in Table 1. The sediment captured in the <br />sediment ponds will be routinely removed and buried in a pit undergoing <br />reclamation. <br />Additional practices that will be used to minimize surface <br />water pollution include rapid stabilization (including reseeding and <br />mulching) of topsoil stockpiles and areas that have been recontoured, <br />placing rip rap at the exit of all culverts to minimize erosion, using <br />straw dikes in ditches along haul roads to trap sediment, and employing <br />• ditch relief valves to return runoff water to its normal water course. <br />Access and haul roads will be routinely maintained by scraping, <br />wetting, and compacting to maintain a hard surface. The outs lopes of haul <br />roads will be topsoiled, seeded, and mulched to prevent sediment runoff. <br />Ditches, culverts, drains and other structures serving to drain haul roads <br />will be periodically cleaned to maintain good drainage. Further, the de- <br />sign of haul roads is within the grade limitations of the regulations. <br />Regarding protection of the groundwater system, The Rockcastle <br />Company will operate well above any perched or continuous aquifers. The <br />proposed mining operation will not encounter any aquifers; therefore the <br />operation will not expose recharge zones (natural or artificial) to po- <br />tential change in the ground water hydrologic balance. Most of the water <br />in the alluvium of Grassy Creek eventually becomes surface flow. The <br />Rockcastle Company recognized that mine pit seepage and percolation through <br />• spoils, road material and then through the soil/shale interface downslope <br />to alluvial water was possible. This was the reason for drilling and <br />8-B1 V-6 <br />