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"Monitoring"). <br />Increased Total Dissolved Solids Loading <br />An increase in salinity, as represented by TDS concentrations, is the major surface <br />water impact caused by the Seneca II Mine. The disturbance of sedimentary rocks <br />during the mining and reclamation process exposes more surface area for the <br />solution of minerals and increases the amount of solute available for transport to <br />surface streams. <br />TDS in Bond Creek has risen from 550 mg/l in 1987 to 2,930 mg/l in 2009. The <br />operator has suggested that TDS levels in Bond Creek will stabilize after mining <br />activities cease, as has been observed in the portion of the Grassy Creek drainage <br />where mining in the original permit area has ceased. <br />A prediction of TDS loading which could be expected to occur in the Fish Creek <br />basin during the months of June through September has been developed by the <br />operator and included in the statement of probable hydrologic consequences. <br />Mean monthly flow and maximum observed TDS concentrations from monitoring <br />of spoil aquifer wells were used in the analysis. Predicted TDS concentration for <br />the downstream location on Fish Creek was calculated using the mass-balance <br />approach. <br />Results of the analysis on Fish Creek predict a cumulative effect from the <br />Cow Camp and Bond Creek drainages to result in an instream TDS concentration <br />of 607 mg/l in Fish Creek below the mine during the month of July. This <br />conclusion was based on assumed discharge of 0.2 cfs with a TDS concentration <br />of 2,245 mg/l from both Cow Camp Creek and Bond Creek. During August and <br />September no flow in the tributaries is expected to reach Fish Creek as surface <br />flow. <br />An evaluation of the effect of increased TDS concentrations in Fish Creek is <br />discussed in Section XIH of this document. entitled Alluvial Valley Floors. Based <br />on the foregoing analysis, the Division makes the finding that the Seneca II Mine <br />site has been designed to minimize off-site surface water impacts. <br />Ground Water <br />Both consolidated and unconsolidated aquifer systems have been identified at and <br />near the Seneca II Mine site. These aquifers may be affected by surface coal <br />mining operations at this site. <br />The Trout Creek Sandstone stratigraphically underlies the Wolf Creek Coal by 70 <br />feet. The intervening strata between the Wolf Creek Coal and the Trout Creek <br />Sandstone, which consists of lenticular sandstone lenses, shale and siltstone, has <br />18