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the di li.t ~~ny of tec: of :ne Madce~ :rc,.ou name.;; rechz rei ny the spoil:. ra Lh Ovate- c`. ~. lesser <br />TGS. 'i ear to year tre ntls in TUS yre haru tc delinea.e probaoly cue to varied sampling <br />techn-,uues. As discussed earlier, these tecnnicues have been standardized. <br />Sulfates at rrell GN-S".5 occasionally exceed irrigation limits, although this voter would <br />be diluted by surface water (i.e., the N'adge Impoundment) before it rvould ever be used fcr <br />such purposes. <br />C. Ground Water Summary <br />All alluvial wells are showing distinct seasonal water level fluctuations in response to <br />periods of precipitation recharue or the lack of precipitation. All alluvial water level <br />fluctuations are within the historic ranges defined for each site except Well GW'-S6-A. <br />This well has shown a slightly greater drop in water level as of the fall of 1986. <br />Gverburden and coal well water levels are fluctuating in response to the precipitation <br />recharge, induced ground water flow to the mine pits, and man-caused changes in reservoir <br />water levels. Water level changes range from fl aving at GW-521 (recharge) to greater than <br />a 50-foot decline at Well Gk'-544P2 (induced pit inflow). The water level in Welt GW'-845P1 <br />has dropped significantly since 1984 with only a partial recovery in 1986. There is no <br />explanation for the water level drop and Peabody has committed to installing two adjacent <br />wells to provide further water level resolution in this area of the mine. <br />Spoil well water levels still indicate that only the furthest downslope highwall portior:s <br />of the spoil exhibit significant amounts of saturation. Levels in spoils wells near the <br />Wadge impoundment are largely controlled by water level fluctuations in the impoundment. <br />Far the ground water quality summary discussion, 1986 maximum, minimum, and mean values <br />for the dominant ions and TDS are compared against the concentration ranges and means <br />established at the wells between 1980 and the end of 1985. Alluvial aquifer rvater quality <br />has not changed appreciably in 1986. The greatest difference was measured below the 004 <br />pond in the Cow Camp Creek alluvium at Well GW-546. The TDS levels increased from 2,400 <br />to 2,800 mg/1. Because the TDS level at the 004 pond averages about 2,100, it is believed <br />that the increase in the alluvium is largely due to seepage from the very hieh TDS Natural <br />Spring ~5 and concentration of salts from evapotranspiration processes in the zcne of the <br />water table surface fluctuations. Chemical constituents accounting for the TDS increase <br />are Ca, Mg, Na, NCO and 50 . <br />3 k <br />29 <br />