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The pool of water at the Fish Creek Borehole built-up, unpumped for approximately two years. When pumping <br />restarted in August 1998, the conductivity had risen from approximately 4000 µmhos/cm to 7500 µmhos/cm <br />(Exhibit 49 Table E49-5). This appears to be due to leaching from the flooded gob. Active mining areas that are <br />~-'pumped regularly have never developed conductivities of greater than approximately 4500 µmhos/cm. <br />In areas where caving of the overburden will occur soon after mining, solute leaching under oxidizing conditions <br />during mine flooding is expected to yield water quality similar to that seen in backfilled areas of the adjacent <br />surface mines. The primary source of inflow. to the underground workings to date (June 1999) appears to be the <br />spoils, deposited updip in the reclaimed surface mine pits. These spoils are parallel most of the southeast side of <br />the underground mine and extend updip from it for over 6000 feet.. The water quality of the main inflows of the <br />mine resembles that of the spoil water. Mine inflow studies have shown the seeps generally have a conductivity of <br />3000 µmhos/cm and dominated by calcium, magnesium, and sulfate ions. A sample from the major inflow in the 6 <br />Right Entry (Exhibit 49, Table E49-1) has a similar mixed cation/anion water type with more elevated sodium and <br />chloride levels with a conductivity of 4660 µmhos/cm. The increased sodium and chloride levels are probably due <br />to some seepage from marine shales overlying the Wadge Overburden and from ion exchange of calcium and <br />magnesium for sodium (see Exhibit 38). While the spoil water is typically acalcium/magnesium -sulfate water <br />(see annual Hydrologic Reports), the 1998 Site 1l5 water is a sodium -sulfate water Exhibit 49, Table E49-1). <br />This change in water type is probably due to ion exchange mechanisms and-Teaching from the overlying marine <br />shales. Overall, flooding of rubblized areas of the mine under oxidizing conditions will tend to result in a water <br />quality with higher sodium concentrations than present backfill water quality, but with a conductivity of 400Q,to <br />7500 µmhos/cm. <br />The water quality resulting from continued solute dissolution or changes in existing water chemistry under raluced <br />conditions is difficult to predict using standard techniques such as leaching tests. <br />- Geochemical modeling was originally used to provide a better understanding of the mineral water relationships <br />that control the equilibrium chemistry of the water in the flooded mine workings. The model used is a code <br />developed by the U.S. Geological Survey referred to as WATEQF (Plummer, L.N., B.F. Jones and H.H. Truesdell, <br />1975, Water Resources Investigations 76-13). The x-ray analysis reports and the Emerson Spectrogra}th analysis <br />provided in Exhibit 36, Geochemical Analysis, indicates that for both roof and floor materials, quartz is the <br />dominant mineral with significant concentrations of iron, aluminum, silicate hydroxides, saponite and clays. <br />The WATEQF model of mined equilibrium with respect to the water analysis from the flooded mine section <br />provided in Exhibit 37, Water Test of Flooded Mine Working, indicates that the water is nearly at equilibrium with <br />respect to quartz and calcite, and super saturated with respect to Fe(OH)3 (Aq). An att~rt to asps the mineral <br />equilibrium of the water analysis in a condition of zero free oxygen failed because the model would not converge. <br />Thus, the chemical composition of the sample would not be expected to remain the same under reducing <br />conditions. We would expect that pH and Eh conditions would revert to premising .conditions because of <br />buffering due to calcite. Elements such as iron, manganese and other trace metals whose soluble concentrations <br />are controlled by pH and Eh conditions would also revert to premising concentrations. Sulfate reduction would <br />not be expected because of limited organic matter to drive the reaction. Therefore, we expect that the water <br />quality of the flooded workings under reduced conditions is largely controlled by the quality of the water, which <br />exists prior to the onset of reducing conditions. Over most of the proposed mining area this will tend to be <br />represented by the predicted water quality for areas where caving will occur before flooding. This applies for the <br />materials tested. Based upon the water quality that has developed in actual flooded areas it appears that overlying <br />marine shales are contributing sodium sulfate and some iron and manganese. However, the other conclusions of <br />the water quality modeling appear to be correct. <br />Tn order to quantify how the solute leaching of the caved overburden material might change over time, the results <br />~.~of a leaching study performed by CYCC on overburden material collected from the adjacent Eckman Park Mine <br />was examined. The study was performed by H.R. Gardner of the USDA and is included as Exhibit 38, Estimation <br />TR99-32 2.05-143 APPR®VRD FEQ 0 ~ 200a 1/3/00 <br />