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• <br />• <br />H~drofogc Owa huoprefauon and hnpacf Am®nrnr fo- the Pt+mU and AdjacouArcar <br />Groundwater <br />Some groundwater wells exhibited slightly changed <br />conditions in some instances and the subsidence <br />monitoring deep wells showed some influence from <br />mining. Overall however, the wells remained favly <br />constant compared to previous years. Most notably, <br />the 1991 data indicate: <br />• Barren Member well H-32 exhibited virtually <br />no response to seazonal influences which <br />indiptes no apparent connexion to surface <br />recharges. <br />• "F"-seam wells SOM-2, and SOM-16 show <br />no seasonal or annual fluctuation and have <br />little or no surface water connection. <br />• Refuse area wells SG-1 and GP-1 continued <br />to show lower levels than in years previous to <br />1987. This is due to persistent lower precipi- <br />tation patterns. <br />• Refuse area wells GP-3 through GP-5, az in <br />previous years, contained no water. <br />• Barren Member well 38-H-1, az previously <br />described, was affected by subsidence. This <br />well has since recovered to pre-mining water <br />levels. <br />• Barren Member well 38-H-2 continued to <br />have casing blockage problems which oc- <br />curred after it was installed. Very little data <br />were collected at this well due to the prob- <br />lem. The psing was apparently damaged by <br />subsidence as described earlier in this sexion. <br />• Barren Member well 38-H-3 provided no <br />useful well data in 1991. Moisture problems <br />with the psing and later communication with <br />the mine workings, probably caused by subsi- <br />dence, precluded the determination of water <br />levels. <br />• Barren Member wells SOM-13 and SOM~O <br />Gave shown seasonal variations in previous <br />years. During 1987, SOM~O showed very <br />little or no response to seasonal fluxuation <br />while SOM-13 was similar to previous years. <br />Since 1988, neither well haz shown a response <br />to seasonal fluctuation. <br />• The shallow subsidence monitoring wells, <br />SW-1 through SW~i, were generally the same <br />az in previous years. <br />Lower Refuse Pile <br />During 1991, mine development waste from the <br />underground mining operations was placed in the <br />lower refuse pile. The lower refuse pile was per- <br />mitted for permanent disposal of some 1.7 million <br />cubic yards of mine development wazte, coal <br />processing waste, and sediment pond cleanout <br />material. In 1991 approximately 54,900 tons <br />(61,300 xr. yd.) were placed in the lower refuse <br />pile in the phase N area. <br />Table 7 shows the 1991 sampling results from <br />monitoring well GP-1 az well az baseline data <br />Table 7 Comparison of CP-1 Baseline and 1991 Sampling Results, West Elk Mine <br />Sampling pH Condux. TDS Temp. Fe Mn <br />Date Turbidity (units) (µmhos/cm) (mg/L) (°G) (mg/L) (mg/L) <br />08/08/85 048 7.5 990 566.0 10.1 <0.02 0.21 <br />08/08/85 048 7.5 990 526.0 10.0 <0.02 0.21 <br />(Dup) <br />. 10/10/85 054 - 693 870.0 7.5 <0.02 0.05 <br />'05107/91- _ <br />- 008 _ <br />s 7.1 958 642 12.2 0.33 0.03 <br />06/11/91. 010 7.5 779 622 10.0 0.16 0.02 <br />`09/19/91.1 __ <br />_ <br />193 > 6.7 898 444 8.8 ~ 81.0 x.02 <br />• <br /> 12 <br />