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wolf Creek coal units were used 1.o determine the pressure heeds above these confined <br />writ ts. <br />Th,e aquifer characteristics of the various units used in the McWhorter analysis are <br />summarized in Table 17.1. These date are discussed in the "Aquifer Characteristics" <br />section of Tab 7. Hydraulic gradient values were determined from mine plan maps and <br />po,t en[iometric surface contour maps. <br />Estimates of the overbu rclen end the wedge and wolf Creek coal ground eater inflow are <br />presented in Tables 17-2 through 17-5. These estimates were prepared assuming that the <br />total inflow would be derived from two principal sources: 1)~ the interception of <br />premining flow rates and e~r a natural hydraulic gradient; and 2) the drainage of ground <br />eater from storage in the aquifers. The folloui ng is a List of assumptions made in using <br />the Mcwhorter pi[ inflow analysis technique. <br />1. Mining intercepts the saturated portion of the pit at the start of each year. <br />2. The length of pit opened on a daily basis is equivalent to the total pit Length <br /> divided by the number of days required to open the pit. • <br />3. Each daily pi[ inc renie nt is instantaneously opened. <br />4. Total pit inflow per year is equal to the sum of incremented daily inf loos for that <br /> year. <br />5. Pit inflows for each year ere independent of residual effects from preceding years. <br /> The method therefore tends to overestimate the amount of water coming into the pit. <br />6. Hydraulic conductivity, storage coefficient, and depth of, saturation are constant for <br /> each mine pit for each year. <br />7. Pit inflow is from two sides for the first year and from one side for all remaining <br /> years (i.e., there is no additional flow from the reclaimed spoils). <br />8. Natural gradient flow is over the entire saturated length of the pit, no corrections <br /> are made for the orientation of the pit in relation to the gradient direction; hence, <br /> the saturated pit length is assumed to be perpendicular to the g ratlient direction. <br />9. Natural-gradient flux is unaffected by reclaimed spoils from the preceding year. <br />10. Fluxes through the ends and bottom of the pit are insignificant and not accounted for <br /> in the program. <br />11. The aquifer is homogeneous, isotropic, and infinite in extent. <br />12. The tra nsmissivity value for a pit is set equal to the product of the saturated depth <br /> of pit and the average hydraulic conductivity. ', <br />2 Revised 03/24/95 <br />