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although some of the fluctuation may be ettribu tad to residual effects of water quality <br />sampling. <br />Yadge Underburden 4ater Levels. six wells (TVU13, 16, 17, 28, 29, and 30) have been <br />installed to monitor water levels in [he Yadge underburden. Exhibits 7-1 and 7-4 show the <br />Yadge underburden monitor well locations and the potentiometrie su rf eee for these wells, <br />respectively. Table 7-2 summarizes the general well completion information for these <br />wells. <br />Pater level date for Yells YYU13, 16, end 17 were collected from August, 1980 through <br />August, 1983 end then again from June, 1990 to the present. Peter level monitoring et <br />Wells YYU28 and 29 began in September, 1990 end at YeLI YYU30 in Oetober, 1990 (Table <br />7-3 ). Monthly water level date for the underburden wells, including hydrograph s, are <br />presented in Appendix 7.2. <br />Ground water in the Vedge underburden occurs under confined conditions at VelLe YYU28, 29, <br />and 30 es indicated by mean water level date end by aquifer teats conducted et each of <br />• these three wells. Wells YYUi6 and 17 ere possibly drilled in unconfined portions of the <br />Yadge underburden es they are both shallow wells (63.4 and 47.8 feet deep, respectively), <br />end the Yadge coal has been eroded away, leaving the underburden exposed et both sites. <br />Both wells have limited saturated formational thicknesses (less then 25 percent each), and <br />both periodically run dry. Yell YYU 13 typically contains less than six feet of water <br />(about 50 percent saturation of the underburden at that location), end may be within en <br />unconfined es well as en unsaturated portion of the Yadge underburden. Mean water levels <br />for all five wells range from 47.13 feet et Yell YVU 17 to 294.74 feet at Well YYU28. This <br />extreme variability is a function of downgredient distance from outcrops and topography. <br />Nean saturated thicknesses in the Yadge underburden range from about two feet et Yell <br />YYU 16 to complete saturation at Wells YYU28 end 29. Table 7-7 presents the saturated <br />thickness and percent saturation at each of the Yadge underburden wells. <br />There appears to be no distinct trend concerning seasonal mean water level changes in the <br />Madge Underburden. The shallowest mean water levels occur in the fall (Yells YYU 13, 28, <br />and 29), summer (Well YYU30), and spring (Yells YVU 16 and 17). Recharge is predominantly <br />in the form of spring snowmelt and summer rainfall, but [here appears to be a delayed <br />• response to recharge events at Yells YYU 13 end 2B, and particularly at Well YVU29. <br />Deepest mean water levels occur in the winter (five wells) end spring (Well YYU29). <br />Seasonal water level fluctuations also show no distinct trends. Minimal seasonal water <br />19 <br />