Laserfiche WebLink
January 1998 Ken Coal Company " 1997Annual HydraloAy Report • CO Permit No. C-80006 • 3 <br />• 3.0 MINE AREA CONFINED GROUND WATER <br />Confined ground water occurs in two water-bearing zones at the mine site: Mine Area Coal <br />Aquifer and Mine Area Overburden. The Mine Area Coal Aquifer is monitored at well 79-6t. <br />This well is located just north of the historic Pit 1, along Bush Draw, in the undisturbed coal seam. <br />The Mine Area Overburden wells aze designated 79-1 and 79-2. These wells aze located at the <br />north and south ends of the historic 720 Pit, adjacent to what was historically the east crest of the <br />pit. See Map 1, Mine Area Monitoring Sites, for general locations. <br />Ground water levels were measured and samples taken from these wells during October 1996 and <br />April 1997, as designated in the Monitoring Plan. The field data from the Confined Ground Water <br />Wells are contained in Exhibit A, 1997 Field Data. The individual analyses of samples collected <br />are presented in Exhibit B, 1997 Coal Aquifer Water Quality Analyses and Exhibit C, 1997 <br />Overburden Water Quality Analyses. The water quality data aze summazized on Table 1, 1997 <br />Ground Water Quality Statistics. Figure 1, Mine Area Aquifer Water Level, shows the relative <br />ground water levels for the coal and overburden aquifers over the past five yeazs. The sample <br />analysis results from the Confined Ground Water wells collected under recommended revised <br />sampling methods starting in April 1996 may be inconsistent with previous results. <br />3.1 MINE AREA COAL AQUIFER <br />• The mine area coal aquifer well (79-61) was monitored and sampled in October 1996 and April <br />1997. Table 1, 1997 Ground Water Quality Statisttcs, presents the water quality summary for the <br />yeaz. In general, the coal aquifer, remains lower in total dissolved solids (TDS) than the <br />overburden aquifer, suggesting little interaction between the aquifer systems. For compazison <br />purposes, the mean field and laboratory pazameter values for Well 79-61 over the last five years are <br />presented in Table 2, Historic Mine Area Coal Aquifer Water Quality Data. <br />Figure 2, EC vs TDS, We11 79-61, presents a comparison of electrical conductance (EC) to TDS <br />concentrations over the last five years. The values plotted represent actual levels measwed rather <br />than a mean value. As seen in Figure 2, EC vs TDS -Well 79-61, the quality of ground water in <br />the coal aquifer exhibits strong seasonal variability, probably related to infiltration of snow melt. <br />3.2 MINE AREA OVERBURDEN <br />Table 1, 1997 Ground Water Quality Statistics, also includes a summary of the field and lab resulu <br />for the yeaz from wells 79-1 and 79-2. <br />For comparison purposes, the mean field and laboratory pazameter values for the last five yeazs <br />are presented in Tables 3 and 4, Historic Mine Area Overburden Water Quality Data. As shown, <br />there have been minor fluctuations in concentration values, but [here have not been identifiable <br />trends on a yeazly basis. Figure 3, EC vs TDS, Well 79-1, and Figure 4, EC vs TDS, Well 79-2, <br />show comparisons and trends over the past five yeazs. <br /> <br />ve/n D^~NU^t ~YD0.O ML TenaMatrix lnc. "P.O. Box 7740!8 "Suamboat Springy, Colorado 80477 "(970) 879~6I603 <br />