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of time. This is performed numerically in the program by subdividing each day into 100 <br /> equal time increments, calculating the flux at the fixed time increments, and using <br /> Simpson's rule to numerically integrate the area under the flux versus time curve. The <br /> daily rate of flow into an open pit decreases to an exponential rate. The program <br /> automatically reduces the number of time increments each day is subdivided into when the <br /> change in daily flow rates is less than one percent. <br /> If the regional gradient is zero (i.e., q r = 0), equation 7 reduces to the following: <br /> 9) t q (t) <br /> SO dt = C/ o -E 3 dqo <br /> /qo(0) qo <br /> and <br /> 10) qo = (1/2E) t-� <br /> The total flow into the pit is calculated by analytically integrating equation 10 with <br /> respect to time. <br /> 11) Q = 2(1/2Et) <br /> Hence, an analytical integration for equation 10 has eliminated the need to perform a <br /> numerical integration, as was the case for equation 8. <br /> The definition of "E" in equation 5 is for the combined case of an unconfined/confined <br /> aquifer system. In order to obtain solutions for the strictly unconfined and confined <br /> cases, the definition of "E" (equation 5) has to be modified. For the case of an <br /> unconfined aquifer, the second and third terms in equation 5 are set to zero and for a <br /> confined aquifer, the first term in equation 5 is set to zero. Equations 8 and 11, which <br /> are used to calculate the total flow into a pit, remain unchanged for all solutions. <br /> The definitions of terms used in pit inflow calculation tables (Tables 17-1 and 17-2) are <br /> as follows: <br /> 1 . Total length of pit is the length in feet that the pit will be open until the next <br /> cut is made and the previous cut is filled in. <br /> 17-8 Revised 04/11/88 <br />