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t � <br /> • Ground Water Drawdown Test Calculations <br /> Former CHASE CHEVROLET Madison Facility <br /> 423 North Madison Street, Stockton, California <br /> Assumptions <br /> A constant 'ground water pumping rate of 6 gallons per minute test conducted on <br /> 24 May 2001 <br /> Wells are screened entirely through the upper water table <br /> Homogenous ground water aquifer characteristics at observation wells EW--2, MW 19A, <br /> MW-20A and MW-21A and extraction well EW-1 <br /> • The Jacobs Straight Line Method (Distance-Drawdown Method) can be utilized to <br /> calculate hydraulic conductivity, transmissrvity(T) and storativity yield utilizing draw-down <br /> versus distance on Berm-logarithmic paper for each well location (Appendix I) <br /> Where <br /> K=hydraulic conductivity <br /> T =transnussivity <br /> S = storativity <br /> Q = constant ground water pumping rate <br /> As = draw-down per 1-logarithmic cycle <br /> . t =time of pump test <br /> ro=intercept of best fit line with the distance axis <br /> b =thickness of aquifer(semi penetrated or exposed) <br /> Calculations <br /> S <br /> Q =6 0 GPM, As =0.66 ft.; t=480 minute; ra= 65 ft. <br /> 1 <br /> T= 70Q--Os —+ 70(6 0 GPM) — 0 66 ft= 636 ft2/day <br /> 636 ft2/day x 1 gpd/ft— 0 134 ft2/day=4,750 gpd/ft <br /> S =T(t) —640 (ro)z= (636 ft2/day)(480 min) --(640)(160)2 = 0.019 <br /> 1 <br /> K W T—.b= 4,750 gpd/ft — 25 feet= 190 ft/day <br /> 190 ft/day(1 cm/sec/2835 ft/day) = 0.067 cm/sec <br /> le' <br />