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-zo- <br />Probable impacts on surface water quality and quantity were previously discussed <br />in Section VIZ of this Findings Document. The operation will disturb 3.1 <br />acres in addition to the 24.2 acres which have already been disturbed. The <br />total surface area disturbed by the operation accounts for 10.5 of the drainage <br />area of Starkville Gulch and 0.07 of the drainage area of Raton Creek. Surface <br />runoff from undisturbed areas will be conveyed around the disturbed area. Total <br />suspended solids concentrations will be controlled by a sedimentation pond. <br />Increases in total dissolved solids concentrations will be minimized by dilution <br />through mixing of surface water discharges with Raton Creek. Surface water <br />will be monitored for changes in water quality and quantity during the operation. <br />Based upon past mining observations, ground water inflow into mine workings is <br />not expected. The potential for adverse effects on surface water through discharge <br />of water from mine workings is, therefore, negligible. Any potential for adverse <br />effects on ground water resources due to communication of aquifers with the mine <br />workings would also be minimal. Ground water which could potentially be <br />impacted by the operation will be monitored for changes in water quality and <br />quantity. <br />There is also little potential for the diminution of surface or ground water <br />quality due to seepage from the permanent coal processing waste pile. The <br />average annual precipitation for the area is low, 14.32 inches. The average <br />annual potential evapotranspiration is estimated at 23.2 inches. Therefore, <br />under normal conditions, much of the water that infiltrates the refuse pile would <br />be transpired by vegetation. Some deep percolation may occur during wet years <br />or during the wetter portions of normal years. <br />The potential impact due to seepage from the waste pile will also be minimal in <br />consideration of the plan for construction of the Wile. Coal processing waste <br />will be compacted in two-foot lifts at the site. This method of construction <br />will significantly reduce the permeability and porosity of the material, thereby <br />inhibiting infiltration and leaching potential. Also, unless further analysis <br />indicates it is not required, the applicant has committed to the placement of <br />four feet of non-toxic material on top of the waste pile after construction. <br />This four feet of cover will reduce the potential for contamination of surface <br />runoff and will act as a buffer between the waste material and the vegetation <br />root zone. <br />Old spoils which currently exist in the area will be reworked during the course <br />of the operation. Zf any toxic materials are exposed during the operation, <br />sufficient measures will be taken to mitigate the effect of these materials <br />on the hydrologic environment. All disturbed areas, including the coal processing <br />waste pile, will be topsoiled and revegetated to create a more stable configuration. <br />In consideration of the measures which will be taken to control erosion and <br />sedimentation during the operation, including the diversion of the natural <br />channel away from the old coal development waste piles, coupled with the proposed <br />reclamation plan, the net effect of the operation should be to improve the <br />existing quality of ground and surface waters. <br />