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• Table 76A <br />Drawdown @ 500 days @ Okie Plaza Well Due to Pumping <br />@ No. 5 !Sine Wells (by Theis solution) <br />Storativity <br />Transmissivity 0.0001 0.0005 0.001 <br />(ft"2 /d) <br />6 s (ft) = 7.1 s (ft)= 1.2 s (ft)= 0 2 <br />40 s (ft)= 2.7 s (ft)= 1.3 s (ft)= 0.8 <br />91 s (ft)= 1.5 s (ft)= 0.9 s (ft)= 0.6 <br />The shaded central box represents the drawdown calculated from the <br />best estimates for aquifer parameters. <br />The mined coal seams are not significant aquifers since there are <br />no known wells drawing water from coals in the area, and coal <br />groundwater is not a significant component in the regional <br />hydrology. <br />Nevertheless, the following analysis was performed to estimate the <br />drawdown impacts of coal mining within the seams because the flows <br />are small and sensitive to assumptions, the effects of local <br />features such as fractures may outweigh distributed flow, and <br />leakage from enveloping strata cannot be readily quantified. <br />Coals have low transmissivity (estimated to be on the order of 30 <br />sq.ft /day, or 224 gal /ft /day). Mine inflows from the coal seams <br />are very small, less than 100 gallons per minute in either seam <br />excluding local flows associated with fractures (which draw <br />groundwater from strata above and below the seams). Enveloping <br />siltstones leak water to the coal seams as the latter are <br />dewatered, diminishing the spreading of drawdown in the seams. <br />Revised 2/16/94 <br />