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• Sodium concentrations in well 008-79-G continua to exceed levels prevalent at all other Mine 3 <br />monitoring locations perhaps as a result of cation exchange as ground water migrates to the greater <br />relative depths penetrated by this well. The aforementioned cation exchange phenomena was thought to <br />be evidenced by the increases in sodium, bicarbonate, and $AR during [he 1993 reporting period. <br />In general, the total dissolved solids concentration in both wells continues to appear to have stabilized <br />within established ranges typical for each site. No anomalous values were encountered during 1998. <br />TDS concentrations in both wells remain within [he norntal range for the Wadge Overburden. The <br />1998 data does not indicate any significant changes in trace metals concentrations. <br />Alluvium <br />The alluvial aquifer vvilhin the mine area is monitored with two alluvial wells (008-AV-I and 008-AV- <br />2) completed in the Foidel Creek alluvium approximately IOOU feet upgradient from the confluence of <br />Foidel and Middle Creeks (see Figure 2). Both wells are completed to the base of Ute alluvium, about <br />14 feet below the land surface. <br />Water Levels - A plot of historic water levels in the two Foidel Creek Alluvial wells and N Foidel <br />Creek as measured at site 304 is presented as Figure 8. The water levels in the wells and stream show <br />the expected typical seasonal interrelationship of relatively rapid increases and declines associated with <br />spring rw~ofl This seasonal variation at these sites is more pronounced here than in other wells as <br />expected because of [lie shallow depths involved and proximity to Foidel Creek. The longer terns trends <br />in water levels at these sites generally parallel the fluctuations observed in annual streanrflows. Tables <br />• 4B and SB provide period of record statistical summary information for water levels at Wells 008-AV-1 <br />and 008-AV-2. Table I 1 B provides period of record statistical summary infornation for water levels a[ <br />surface water monitoring site 304. <br />Water quality -Water quality data for the Foidel Creek Alluvium wells is presented on Tables 4, 4A, 5, <br />and SA. Water quality data for Foidel Creek Site 304 monitored in association with the alluvial wells is <br />presented on Tables 11 and 11A. Only water level information was recorded during 1998 for site 304. <br />Plots of historic field conductivities for both wells and dissolved solids for welt 008-AV-2 are presented <br />as Figtues 9, 10, and 1 L Water quality constituent wncentrations for all paratneters monitored during <br />1998 were within the established ranges historically associated will[ each site. The total dissolved solids <br />concentration in the Foidel Creek alluvial aquifer as measured at well 008-AV-2 have appeared to be <br />steadily increasing since approximately 1988 (see Figure 11). Values recorded in 1998 continue to <br />follow that trend. Seasonal variations in field conductivity are evident in the alluvial wells. This is <br />likely associated with the flushing effect of the relatively low dissolved solids surface water recharging <br />the alluvial aquifer during spring twioff. <br />The 1998 data does not indicate any significant changes in trace metals concentrations alQtough iron <br />and manganese values remain variable. Manganese and iron concentrations documented during 1998 <br />maintained levels within the historical ranges established at this sift. <br />Spoils <br />Two wells in the backfilled area of Mine 3 (008-SP-4A and 0(18-SP-SA) were installed in 1985 to <br />monitor water levels and water quality in mine spoils (see Figure 2). One well, 008-SP-4A, remained <br />. dry since it was installed. During 1992, the well was deterntincd to have a separated casing. As a <br />result, CYCC installed a replacement spoil momtormg well (1108-SP-4B) near the northern embankment <br />3 <br /> <br />