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' Ground Water Drawdown Test Calculations <br /> Former CHASE CHEVROLET Madison Facility <br /> 423 North Machson Street, Stockton, California <br /> Assumptions <br /> ' • A constant ground water pumping rate of 6 gallons per nunute 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 /> ' a The Jacobs Straight Line Method (Distance-Drawdown Method can be utilized to <br /> g {� ) <br /> ' calculate hydraulic conductivity,transrrnssivity(T) and storativity yield utilizing draw-down <br /> versus distance on serrn-loganthnvc paper for each well location (Appendix 1) <br /> Where <br /> ' K= hydraulic conductivity <br /> T = transmissivity <br /> ' S = storativrty <br /> Q = constant ground water pumping rate <br /> • <br /> As = draw-down per 1-loganthrmc cycle <br /> ' t= time of pump test <br /> r. = intercept of best fit line with the distance axis <br /> ' b= thickness of aquifer (sem penetrated or exposed) <br /> Calculations ------� <br /> ' Q = 6.0 GPM; As =.1 ft.; t=480 minute; ro =Wit. <br /> �L �6 <br /> -- <br /> T= 70QAs -470(b 0 GPM) —O,�ZS it= tZ/day <br /> ' <br /> 3,9Q-ft'/day x 1 gpd/ft— 4 134 ftz/day apd/ft <br /> S = T(t) — 640 (ro)2= (3,360 ft2/day)(435 nun) — (640)(160)' = 89 G © �� <br /> K= T —b= 25,-O75'gpd/ft —25 feet =j,,063-ft/day <br /> ' 1,0 ft/day(1 cm/sec/2835 ft/day) cm/sec <br /> jo a 00- <br />