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January 7995 Kerr Coal Company '" 1999 Annual Hydrology Report • 3 <br />3.0 MINE AREA CONFINED GROUND WATER <br />Confined ground water falls into two categories: Mine Area Coal Aquifer and Mine Area <br />Overburden. <br />The Mine Area Coal Aquifer is monitored at a well designated as 79-61. This well is located <br />1 just north of Pit 1, along Bush Draw, in the undisturbed coal seam. <br />The Mine Area Overburden wells are designated as 79-1 and 79-2. These wells are located at the <br />north and south ends of the 720 Pit, adjacen[ to the east crest of the pit. <br />Water levels were measured and samples taken during October 1993 and April 1994 as <br />designated in the Monitoring Plan. The field da[a from [he Confined Ground Water Wells are <br />contained in Exhibit A, 1994 Field Data. The individual analyses of samples collected are <br />presented in Exhibi[ B, 1994 Coal Aquifer Water Quality Analyses and Exhibit C, 1994 <br />1 Overburden Water Quality Analyses. The data are summarized on Table 1, 1994 Ground Water <br />Statistics. Figure 1, Mine Area Aquifer Water Level, shows [he rela[ive water level for the coal <br />and overburden aquifers over the past five years. <br />3.1 MINE AREA COAL AQUIFER <br />The mine azea coal aquifer well (79-61) was monitored and sampled in October 1993 and April <br />1994. Table 1, 1994 Ground Water Statistics, presents the water quality summary for the year. <br />On average, the coal aquifer remains much lower in total dissolved solids than the overburden <br />aquifer, suggesting little interaction between the aquifer systems. For comparison purposes, the <br />mean field and laboratory parameter values for the last five years aze presented in Table 2, <br />Historic Mine Area Coal Aquifer Water Quality Data. Figure 2, EC vs TDS, Well 79-61, <br />presents a comparison of elettrical conduttance to total dissolved solids concentrations and <br />trends over the last five years. The values plotted represent attual levels measured in October <br />and April rather [han a mean for the year. <br />3.2 MINE AREA OVERBURDEN <br />Table 1, 1994 Ground Water Statistics presents a summary of the field and lab results for the <br />year frocn wells 79-1 and 79-2. <br />For comparison purposes, the mean field and laboratory parameter values for the last five years <br />l are presented in Tables 3 and 4, Historic Mine Area Overburden Water Quality Data. As <br />j shown, there have been minor fluctuations in concentration values, but there does not seem to <br />be an identifiable trend. Figure 3, EC vs TDS, Well 79-1, and Figure 4, EC vs TDS, Well 79-2, <br />show cotnparisons and trends over the past five years. <br />~a s~~ w' v~°~ TenaAfcrnz lnc. " P.O. Boz 774018 "Steamboat Sprirsgr, Colorado 80477 (303f 879-6260 <br />