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bicarbonate, sulfate type with a relatively low concentration of total dissolved solids. <br />Mine water monitoring from 2005 to 2009 reports Electrical Conductance (EC) values <br />ranging from 1798 to 2013 umho/cm with a average of 1867 and a pH range of 7.3 to <br />8.8. <br />A coal mine waste pile is planned for the area south of the office area. The coal mine <br />waste pile has a footprint of 13.2 acres. The average precipitation in the area is 18.1 <br />inches based on the Ashford Canyon rain gage. Assuming all of the rainfall leaches <br />through the pile during the year, the resultant leachate flow would be 12.3 gpm (0.03 cfs). <br />However, a more realistic assumption would be to assume only 5% of the total rainfall <br />would leach through the pile during the year as most precipitation is lost to runoff; the curve <br />number for the coal mine waste pile is equal to 90. If not lost to runoff, the water can be <br />lost via evaporation from the soil or it can be transpired by vegetation before it can <br />percolate into the groundwater system. Therefore, assuming 5%, the flow would equal <br />0.62 gpm (0.001 cfs). The coal mine waste has a pH of 7.29 su and an EC of 3410 <br />umhos/cm. <br />In order to evaluate the potential impacts of the gob pile leachate, it is necessary to <br />combine the leachate with the mine water to get a combined flow rate and combined <br />conductivity. Although the gob pile is not yet in place at the time of this writing, and <br />therefore doesn't impact the surface or groundwater, it is necessary to evaluate the <br />contribution of the gob pile leachate as if it were contributing to the mine water flow rate <br />and conductivity. In addition, it is necessary to combine the sediment pond leachate with <br />the coal mine waste pile leachate, and mine water discharge to get a total potential <br />discharge to East Salt Creek. In order to account for the leachate from the Sediment Pond <br />into the groundwater, and thus into East Salt Creek, steady-state seepage at full -pool was <br />assumed. Using a hydraulic conductivity of 1(10-4) ft/sec, GeoSlope 2007 calculated the <br />flow to be 0.07 gpm, as shown in Appendix S. Discharge from the sediment pond is <br />disregarded in this analysis as the flow is infrequent. During the last five years, the existing <br />sediment pond only discharged once. Since the existing and proposed ponds are designed <br />and managed according to the same DRMS rules, discharge from the new pond will not be <br />considered. <br />Therefore, combining 0.62 gpm (gob leachate) with an EC of 3,410 umhos/cm to 0.07 gpm <br />with an EC of 367umhos/cm (sediment pond leachate flow with sediment pond surface <br />discharge EC) to 100 gpm flow (mine water flow rate) with a 1867 umhos/cm results in a <br />combined flow of 100.69 gpm (0.22 cfs) with an EC of 1854 umhos/cm. These combined <br />values (gob pile leachate, sediment pond seepage and mine water discharge) from here <br />forward will be referred to as 'combined' instead of mine water flow rate. <br />Data gathered for SW -1 and GW -3 are presented below. The Division's 1987 Material <br />Damage guidelines require any measured salinity values over 1000 umhos/cm be <br />reported as 'suspect' values. Since baseline values for SWA and GW -3 far exceed the <br />Division's 'suspect' levels, the Operator compiled data in order to demonstrate <br />combined discharge does not add salinity to the already high values, rather, can only <br />lower the salinity in SWA and GW -3 during the irrigation season. By improving the <br />Appendix N — PR -02 - 3 - 10/10 <br />