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structural roll in the coal seam. This saturated area of the workings is <br />structurally and hydrologically separate from the other portions of the <br />Caldirola workings and would not be affected by dewatering downdip. Based <br />on the relatively good quality of this water, it is believed that recharge to this <br />isolated pool is from surface infiltration from the immediate area above. This <br />would explain why dewatering activities of the Twin Pines No. 2 Mine <br />apparently had no effect on the water levels of the Caldirola No. 2 well. <br />Another well, TPW-1, was monitored over the operations and reclamation <br />period until permit revocation/bond forfeiture. This well was completed in a <br />thick sandstone of significant aerial extent about 10 feet below the coal seam <br />to be mined in the Twin Pines No. 2 Mine. The Division stated in the 1983 <br />written findings that the ground water balance could be altered by disturbing <br />the shale that separated the coal seam from the sandstone unit below. <br />Additionally, the Division estimated an increase of about 80mg/1 in total <br />dissolved solids (TDS) in this sandstone unit could result from mining. <br />TPW-1 <br />Date Water level (feet) Cond. (umhos/cm) pH <br />May 1985 153 600 8.2 <br />July 1990 149 780 8.5 <br />June 1993 143 880 8.5 <br />June 1995 145 <br /> <br />928 <br />F <br /> <br />7.8 <br />F <br />j] <br />Using a accepted general ratio of TDS =(.74)Conductivity, total dissolved <br />solids may have increased as much as 240 mg/1 over the period of record. <br />While some of this increase could be attributed to mining, data collected from <br />the Caldirola No. 2 well over the identical period would indicate that as much <br />as 126 mg/l of the 240 mg/l increase maybe attributable to climatic changes. <br />Therefore, mining may have increased the TDS in well TPW-1 by as much as <br />114 mg/l, some 34 mg/l over the Division's estimate in the original findings, <br />which is within any reasonable margin of error for such an estimate given the <br />limited amount of data, the heterogeneous geologic and hydrologic <br />conditions, and impacts and interactions caused by extensive historic mining <br />in the area. <br />Mining and subsidence causes fracturing of rocks above the mined and <br />subsided area. Other than one deep well downstream of the Lewis Gulch/Oak <br />Creek confluence that was not within the area affected by mining and <br />subsidence, no other deep ground water wells exist in the affected area above <br />the mined area or within the radius of influence of the mined and subsided <br />15