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• Specific Conductivity/Total Dissolved Solids <br />Specific conductivity (Figure 23) and total dissolved solids (Figure 29) <br />values for the three alluvial wells have remained fairly constant over the majority <br />of the period of record. While Conductivity and TDS values at sites TR-3 and TR-9 <br />are consistent with values obtained during the baseline studies, these parameters <br />and several others have elevated rapidly and remained elevated at TR-1.5 since 1995. <br />The source of the elevated values is not readily identifiable. A few factors which <br />may have contributed to the elevated levels were mentioned in the 1996 Report (i.e., <br />inundation of the area in late spring cf 1995 and the laying of telephone cable <br />immediately upstream of the area during the summer of 1995). If the elevated levels <br />resulted from those activities, the concentrations should have returned to more <br />historic levels during the 1996 and 1997 monitoring periods. However, the <br />concentrations have remained elevated, and it appears that the alluvium in this area <br /> is reflecting upstream alluvial water containing high levels of TDS, possibly from <br /> an old abandoned underground mine up the Little Trout Creek drainage. This <br /> conclusion is based partially on the similarity of the water quality between TR-1.5 <br /> and WR-1. As previously discussed in the surface wate r section, data taken between <br /> October 1990 and August 1992 is belie ved to be invalid due to instrum ent errors. <br />Conductivity and TDS in Well WR-1 have progressed from an elevated state each <br />spring to a lower state in the fall for the past several years. This phenomenon was <br />caused by infiltration of snowmelt water leaching various minerals within the <br />unsaturated zone of reclaimed spoil. As the enriched flow was released over the <br />course of the summer, the conductivity values lessened to that of the stagnant <br />saturated zone. The 1995-1997 data suggests that the unsaturated zone may be almost <br />depleted of leachate. The mounded aquifer exhibits a more diluted state each spring <br />with a return to steady-state as the summer progresses. <br />Calcium/Magnesium/Sodium <br />Calcium (Figure 25) is the major cation found in all of the wells with <br />concentrations of sodium (Figure 26) and magnesium (Figure 27) occurring in lesser <br />quantities. TR-1.5 generally contained the lowest concentrations of cations with a <br />slight increase occurring downstream at TR-3 and TR-9 for the majority of the <br />record. However, elevated levels of these parameters at TR-1.5 began to occur in <br />1995 consistent with the elevated Conductivity and TDS levels previously mentioned. <br />The sodium level for WR-1 of 454 mg/1 obtained during October 1991 is believed <br />to be an analytical error. Levels measured prior to and after that sample date do <br />not support the high concentration and followed the expected trend. <br />31 <br />