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1 <br /> ' GROUND WATER DRAWDOWN TEST CALCULATIONS <br /> CONSTANT RATE PUMT NG TEST <br /> I Local Food Store <br /> 2650 Monte Diable Avenue, Stockton, California <br /> 1 y <br /> Assumptions <br /> ' 0 A constant ground water pumping rate of 4 gallons per minute test conducted on 04 and <br /> 05 Februay 2002 <br /> • Wells are screened entirely within the upper water table <br /> • Homogenous ground water aquifer cliaractenstics at observationwells OW­1,MW-4,OW-2, <br /> ' MW-3, MW-1, OW-3 and OW-4 and extraction well MW-2 <br /> • The Jacobs Straight Line Method (Distance-Drawdown Method) can be utilized to <br /> calculate hydraulic conductivity,transrrussivity(T) and storativity yield utilizing draw-down <br /> versus distance on semi-loganthrnic (Appendix G) <br /> Where <br /> ' K=hydraulic conductivity <br /> T = transrnissivity <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 /> rQ =4.0 GPM; As =4.6 ft., t=2,282 minutes; ro = 220 ft. <br /> ' T = 70Q--As 4 70(4 0 GPM) — 4 6 ft= 60.9 fe/day <br /> 60 9 ft'/day x 1 gpd/ft -- 0 134 ft'/day= 454.5 gpd/ft <br /> S =T(t) — 640 (ro)' _ (60 9 ft'/day)(2,282 min) — (640)(220 ft)' = 0.004 <br /> K = T —b = 454 5 gpd/ft— 12 1 feet = 5.03 ft/day <br /> ' 5 03 ft/day (1 cm/sec/2835 ft/day) = 0.0018 cm/sec <br /> 1 <br />