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• <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 transmissivity value for a pit is set equal to the product of the saturated depth <br />of pit and the average hydraulic conductivity. <br />• <br />13. The number of pits mined per year must be a whole number, with tha number of days all <br />pits are open for a year being less than or equal to 365 days (i.e., 1 pit open for <br />365 days, 2 pits open 182 days each, 3 pits open 121 days each, etc.). <br />The overburden pit inflow values were calculated using unconfined ground Hater flow <br />equations and the Dakota coal pit inflow values were calculated using confined equations. <br />Pit inflow calculations are based on the following procedures developed by McWhorter <br />(1982). Equations 1 and 2 describe one-dimensional unconfined and confined flow. <br />1) d / dh~ dh <br />K dx h dx - Sya dt <br />O~x~ Lu <br />2) T d2h _ S dH <br />dx2 dt <br />where: <br />Lug x~ Lc '+ Lu <br />K is the hydraulic conductivity, L/t; <br />T is the transmissivity, L2/t; <br />Sya is the specific yield, dimensionless; <br />5 is the confined storage coefficient, dimensionless; <br />h is the head in the confined zone, L; <br />H is the pressure head above the confining unit in the confined zone, L; <br />x is the location in eartesian coordinate space, L; <br />t is time, t; <br />Lu is the distance to the unconfined-confined zone interface, L; and <br />Lc is the distance from the unconfined-confined interface to the undisturbed zone, L. <br />Integrating equations 1 and 2 with respect to x over the intervals in which they are <br />applicable, applying Leibnitz's rule, and summing the two solutions results in the <br />following equation: <br />17-6 Revised 04/11/88 <br />