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2. Length in water (feet) is the same as the total length of the cuts for each year. <br />• <br /> 3. Time in water i s the result of dividing the length in water for a given year by the <br /> pit advancement per day for the same year. This value represents the number of days <br /> the pit will be open and subject to pit inflow each year. <br />4. Pit advancement is the constant length in feet per day that the pit will advance for <br />the year. It is calculated by dividing the total area to be mined in a given year by <br />a constant pit width. The constant pit width use for years 1 and .2 is 150 feet. For <br />years 3, 4, and 5 a constant pit Width of 105 feet was used. <br />5. The geometric mean values for transmissivity, hydraulic conductivity, and storage <br />coefficient were collected from aquifer tests and determined by using the following <br />equation: <br />X9 = (X1*X2*X3...Xn)1/n <br />6. The saturated thickness for each aquifer was based on water level monitoring values <br />that were representative of the area to be mined in a given year. <br />• <br />7. ONATURAL is the amount of aquifer through flow which will be intercepted by each <br />years pit advancement in gallons. <br />8. QDRAINACE is the linear portion of inflow from aquifer storage in gallons. <br />9. OTOTAL is the sum of QNATURAL and QDRA INACE for a given year in gal loos. <br />Mining in Nucla East is projected to intercept both the overburden and Dakota coal <br />aquifers for all five year. <br />MODFLOW Analysis for Calculating Pit Inflows and Drawdowns. <br />Introduction. MODFLOW was used to model changes in the ground water system in the <br />vicinity of the Nuc1a mining complex caused by pit dewatering. Simulations for both the <br />overburden and coal aquifer were performed. No modifications to the MODFLOW code were <br />necessary. <br />17-9 Revised 04/11/88 <br />