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mined uphill of well GF4. TDS data from this well does not show a <br />trend. <br />Backfill well, GFS, has been monitored only approximately one <br />year, but its limited data indicates that TDS is increasing with time <br />in this aquifer (see Figure B-17). The most recent TDS of 1240 mg/1 <br />is greater than the HI aquifer would have likely contained in this <br />area prior to mining, as expected. TDS in backfill aquifers should be <br />elevated for several years after mining until the readily dissolveable <br />constituents are removed. <br />The QR aquifer is monitored downgradient of a portion of the <br />mined E pit at well GF6. TDS measurements from this well does not <br />show any effects from mining. <br />The U aquifer is also monitored in well GZ2, which is <br />approximately one mile upgradient of D well GF2. A steady <br />concentration in well GZ2 has been observed. 7'he December, 1982 <br />measurement for TDS is thought to be too low because the DSSUM value <br />indicates the TDS should be close to the other values. TDS is <br />significantly higher at this upgradient well than i{t is at well GF2. <br />. Wells GBB1 and GBB2 have been influenced by cement contamination <br />and, therefore, their TDS values have also been significantly affected <br />by the cement. The December, 1985 sample from well GBB1, after the <br />mechanical bailing of this well, is thought to represent water quality <br />conditions of the Third white Sandstone fairly well at this site. <br />Plots of wells GBB1 and GBB2 (see Figures B-20 and F3-21) should not be <br />used to indicate changes in these two aquifers. Ttie alluvial aquifer <br />TDS at well GBB3 has been fairly steady with time (:;ee Figure B-22). <br />The TDS concentration from Pyeatt alluvial well P1 has generally <br />decreased with time, except for an increase in August, 1983. This is <br />probably due to the increase in base flow in Pyeatt during the last <br />couple of years which has increased the amount of water available for <br />recharge to this aquifer. The TDS for water from tkie Lewis Shale well <br />P3 has increased with time except for the August of 1984 measurement. <br />Water quality in a shale aquifer as the Lewis Shale would be expected <br />to contain high concentrations at times. TDS conncentration in the <br />Second White Sandstone well (P5) has varied concentrations with time <br />(see Figure B-25). This variation is probably c:aused by variable <br />amounts of recharge. The TDS concentrations from the Third White <br />Sandstone (P8) in this area have been much more st,sble. Figure B-26 <br />shows a gradual increase in concentrations with time, except for the <br />August, 1983 value. <br />M Only a few TDS data values are available for alluvial wells J1 <br />and Coy. Figure B-27 indicates an increasing trend in TDS for the <br />3-3 <br />