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The amount of seasonal water level fluctuation is quite varied, but shows no distinct • <br />trend. Yells YOV15, 19, 20, 27, end 29 typically show the least seasonal fluctuation, but <br />thic may be due to the fart that they ere typitally dry, or Contain little water. Yell <br />YOY1 displays the greatest amount of variability, with water levels renginB from 1.13 feet <br />in the spring to 29.77 feet in the fall. It is suspected, however, that the bottom seal <br />on this well has failed, and thus the well does not truly monitor the overburden (see <br />third paragraph above). Well YOVB may have suffered en annular seal failure, es the most <br />recent water level measurements taken at this well (June end August, 1993) show levels <br />elevated nearly 70 feet above the previous historic average of 121.8 feet end ere also <br />higher than those water levels observed et adjacent Yells YOV9 and 10. The completion <br />summery for Nell YOVB (Page 7.1-57) also indicates a possible annular seal failure. <br />Residual effects of water quality sampling may also play a role in the fluctuating water <br />levels of the Yedge overburden wells. <br />Nad9e Coal Yeter Levels. Thirteen monitor wells (TY2, 7, 11, 12, 14, 18, 21, 23, 24, 26, <br />28, 29, 30) have been installed to monitor water levels in the Yadge coal seam at Toast. <br />Exhibits 7-1 end 7-3 show the Yadge coal monitor well locations and the potentiometric <br />surface for the Wedge cos L, respectively. <br />Water level date for Yells TN2 to 26 were collected from August, 1980 until August, 1983 <br />end then again from June, 1990 to the present. Yell YY24 collapsed some time after <br />October, 1991 end thus has not been monitored since that date. Meter level monitoring et <br />Yells YN28 to 30 began in June, 1990. Monthly water level data for the Madge coal wells, <br />including hydrograph s, are presented in Appendix 7-2. Table 7-2 summarizes the general <br />well completion information for these wells. <br />Ground water in the Yadge coal seam occurs under confined conditions et ell wells except <br />Nell YY2, where leaking annular and bottom seals are thought to be responsible for both <br />abnormally shallow water levels and for a measured transmissivity of nearly 2100 gpd/ft. <br />(calculated storativity of 0.014). The completion summary for Nell YY2 (Page 7-1-93) <br />indicates bentonite pellets were used for both the seals. It is suspected these seals <br />have failed. The presence of water flowing outside the casing a[ the surface also <br />indicates seal failures. In comparison, aquifer tests performed et Yells YN23, 28, 29, <br />• <br />and 30 yield trensmissivities of 0.11 to 1.95 gpd/f t, and storativities in the 10-ES <br />range. Yells TY14 and TN26 are dry or contain little saturated formational thickness. • <br />Xean water levels for the confined wells renpe from 17.57 feet at Vell YY24 to 158.03 feet <br />16 <br />