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the coal development waste pile and the passage of storm runoff <br />over disturbed areas. Total dissolved solids (TDS) iron and <br />• <br />sodium levels will increase slightly. Total suspended solids ~ <br />('tSS) will go up within the disturbed area, but treatment with <br />sedimentation ponds will lower the concentration of TSS derived <br />from storm runoff below natural conditions, TSS concentrations <br />associated with mine discharge pond eff:Luent may be higher than <br />natural levels, but will be controlled to standards set by <br />NPDES of 35 mg/1 average, and 70 mg/1 maximum to limit the <br />potential impact to the hydrologic balance. <br />The mine water discharge water a.t the Golden Eagle Mine <br />is described as a slightly alkaline, saline, sodium bicarbonate <br />water of low hardness. The pH ranges from 7.2 to 9.6, <br />averaging 8.42, the specific conductance has ranged from 133 to <br />2185 umhos/cm averaging 12,52 umhos/cm, and the total dissolved <br />solids has ranged from 106 to 2250 mg/1 averaging 87.6 mg/1. <br />Total iron concentrations have ranged from 0.025 to 4.9 mg/1 <br />averaging 0.77 mg/1. Total manganese concentrations have <br />ranged from 0.005 to 0.06 mg/1 averaging <0.0136 mg/1. The <br />•, <br />sodium absorption ratio has averaged 31.3. <br />The Middle Fork, of. the Purgatoire at Stonewall is a <br />_ <br />slightly alkaline, calcium bicarbonate water of moderate <br />salinity and low hardness. The WWL report (Exhibit 6) <br />estimated the loading of chemical parameters associated with <br />mine water discharge on a low flow of 5 cfs and a mean flow of <br />20 cfs. The mine has not ,experienced a flow near 5 cf:s, so it <br />is difficult to evaluate the veracity c>f that projection. The <br />mine has seen flows in the range of 20 cfs, and the November, <br />1993, results at PRS-3, located downstream of the mine on the <br />North Fork of the Purgatoire River, at 13.13 cfs sugg~=_st that <br />the predicted concentrations of calcium, chloride, m.sgnesium <br />and manganese were higher than expected. The Stonewall and <br />site PRS-1 data reflect a calcium bicarbonate water with a mean <br />TDS of 166 mg/1; the mine is discharging a sodium bicarbonate <br />water with a mean TDS of 815.5 mg/1 versus the 11.12 mg/1 <br />anticipated earlier. • <br />2.05-39 (Revised 04/27/94) <br />