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Pump Test Calculations <br /> 500 . 5 cf/s 2 . 6 gal/min Q = flow from well under normal conditions <br /> 465 . 1 cf/s 2 .416 gal/min Qavg = average flow rate from well <br /> 4 hours 240 minutes t = time that the well is pumped under normal conditions <br /> 2 . 78 m 9 . 13 feet H = open interval or length of well screen (feet) <br /> 0 .42 MW-23 @ 15' n = aquifer porosity <br /> 28 .96 m 95 feet R = radius of influence , extrapolated from graph <br /> 6 . 5 feet b = aquifer thickness (approx. 14 . 5' to 20 ' bgs ) <br /> 2 .416 gal/min Qavg = average flow rate from well <br /> 3 . 99 ft. max sw = drawdown or change in hydraulic head <br /> 0 . 6065 gpm/ft Sc = specific capacity = Q / sw <br /> Dupuit-Thiem Equation : sw = (Q/27cT) ln ( R/rw) solve for T <br /> Transmissivity T = ( 1 /27c) In ( R/rw) (Q/sw) <br /> 95 feet R = Radius of Influence ( in feet) <br /> 0 . 167 feet rw = radius of the well (2") <br /> 2 .416 gal/min Q = average flow rate from well <br /> 3 . 99 ft. max sw = drawdown or change in hydraulic head <br /> T = ( 1 /27c) In (95 feet/0 . 167 feet) (2.416 gpm/3 .99 feet) <br /> =(0 . 5*3 . 1416 )*( LN (95/0 . 167 ))*(2 .416/3 . 99 ) <br /> 6 . 033694866 = T in gpm/feet <br /> Theis nonequilibrium equation : Sc = 47iT / ( In (2 . 25 T tp /rw^2 S ) <br /> Storativity S = rw^2 * (2 .25 T tp) / (eA (4pT/Sc) <br /> 6 . 034 gpm/ft T = Transmissivity <br /> 240 min tp = time pumping <br /> 0 . 167 feet rw = radius of the well (2" ) <br /> 0 . 6065 gpm/ft Sc = specific capacity = Q / sw <br /> 0 . 167 feet rw = radius of the well (2" ) <br /> S = 90 . 86788/e^125 . 02 = 46.23 <br />