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concentrations during the spring and increasing gradually as summer progresses into • <br />winter. <br />Sulfate concentrations in the Yadge coal seam have generally been measured less than 500 <br />mg/l, although one value of 570 mg/l was observed in the first sample collected at Vell <br />YV28. Sulfate, like TDS in the Yadge coal, exhibits little seasonality. <br />Field pH measurements have ell ranged above 7.0 S.U. with the exception of Yell YY23, <br />which has shown several pH values slightly lower then 7.0. Representative maximum pH <br />values have not exceeded B.b S.U., es the first two measurements collected at Yell YN18 <br />(11/80 - 9.9; 2/81 - 4.2, see Appendix 7-4) are not considered representative. No <br />seasonal pattern for pH is evident in the Vadge coal. <br />Hardness as CaC03 is variable among the Wedge coal wells, ranging from 64 mgll at YY29 up <br />to 862 mg/t et YV28. Initial analyses for hardness et YY29 (11/90 to 10/91, see Appendix <br />7-4) are considered to be unrepresentative, as subsequent hardness values have been Less <br />than 110 mg/l. Ground water in the Yadge coal seem monitored by Vell YV29 is considered <br />moderatel y hard, while et all other wells, is considered hard to very hard. No clear • <br />seasonal pattern in hardness is evident, although at Yella YV2 and YV28, the data suggests <br />hardness is lower during the spring end early summer end slightly higher es the seasons <br />progress to winter. ' <br />Detectable concentrations of several trace elements were measured in the Yadge coal seem, <br />including 8e, B, F, Fe, Si, and 2n. Of these, only barium, end silica were measured at <br />concentrations above 1.0 mg/l. Barium has been measured in excess of 1.0 mg/l at Yell <br />YV30 only, end silica was commonly analyzed at levels above 1 mg/l prior to 1990 at Vells <br />YY2, YY18, end YY23. The other four trace elements have been measured et concentrations <br />well below 1 mg/l. <br />Wedge Underburden. Wells YVU 13, TVU28, YVU29, end YVU30 monitor water quality in the <br />Yadge underburden. Only one set of field parameter measurements have been collected et <br />YVU 13 due to insufficient water for sampling the well bore. Yell YYU28 is located in the <br />northeastern portion of the mining Brea, end Yells YVU29 end YYU30 are both situated in <br />the mid- and southwestern portions of the Yoast mining area (see Exhibit 7-1). <br />Table 7-17 presents summary information regarding water types depicted on trilinear • <br />diagrams end table Listings of percent milli equivalent values found in Appendix 7-4. <br />52 Revised 03/01/95 <br />