Laserfiche WebLink
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 = O), equation 7 reduces to the following: <br />r <br />9) St q (t) <br />dt = 1 0 _E 3 dqo <br />0 q (0) =ao q <br />0 0 <br />and <br />0 <br />The total flow into the pit is calculated by analytically integrating equation 10 with • <br />respect to time. <br />11) 0 = 2(1 /2 Et)~ <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 far 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 /> • <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 />8 <br />