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Ground Water Drawdown Test Calculations <br /> PACIFIC MINI MART <br />' 4511 Pacific Avenue, Stockton, California <br /> .1 - <br /> ­�ssumpttons <br />' A constant ground water pumping rate of 5 GPM for tests conducted on 27 March 2001 <br />' 0 Well EW-1 is screened entirely through the upper NNater table, 25 to 45 feet bsg <br /> • Homogenous ground water aquifer characteristics at obscnation wells MW-4 through MW- <br /> 6, vapor wells VW-I and ground water extraction well EW-I (soil boring logs) <br /> e The Distance-Drawdown Method was used to calculate transmissivity(T) and storattvity <br /> (S) and hydraulic conductivity (K) utilizing draw-down versus distance (feet) on semi- <br /> logarithmic paper for each well location <br /> • Equations <br /> IT = 70Q/ds S = Tt/640 (r.)' K= T/b <br /> Where <br />�. K=hydraulic conductivity <br /> T = transmissivity <br /> S = storattvrty <br /> Q — constant ground water pumping rate =5 0. GPM. <br /> As = draw-down per 1-loganthmic cycle (Appendix H) = 1.7 ft. <br /> t =trnne of pump test (Appendix G) = 720 minutes <br /> ro = Intercept of best fit line with the distance axis (Appendix H) = 65 feet <br /> b = aquifer thickness (semi penetrated or exposed screen length) <br /> 29 March 2001 <br /> T= 70(5 gpn-i)/l 7 feet = 205 feet'` /day or <br /> 205 feet2 /day(1 gal day/f1/0 134 feet2 /day) = 1,536 gal day/feet <br /> S = 205 feet' /day (720 minutes) /640 65 feet)2 = 0 054 <br /> K— 1,536 gal day/feet 125 feet = 61 44 feet/day <br /> K= 6144 feet/day (1 cm/sec/2835 feet/day) = 0 022 cin/sce <br /> IAdvanced GeoEnviro«Ineatal [oe <br />