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Ground Water Drawdown Test Calculations <br /> FORMER STOCKTON PLAUNG FACILITY <br /> 632 South El Dorado Street, Stockton, California <br /> Assumptions: <br /> • A constant ground water pumping,rate of 5 GPM for tests conducted on 18 October 2001. <br /> • Well'EW-1 is screened entirely through the upper water table, 30 to 60 feet bsg. <br /> I <br /> • Homogenous ground water aquifer characteristics at observation wells MW-3 through } <br /> MW-5, vapor wells VW-1 to VW-4 and ground water extraction well EW-1. <br /> i <br /> • The Distance-Drawdown Method was used to calculate transmissivity (T) and storativity f <br /> 11- <br /> (S) and hydraulic conductivity. (K) utilizing draw-down versus distance (feet) on semi- <br /> logarithmic paper for each well location. <br /> • Equations: <br /> T = 70Q/ds S = Tt/640 (r.)Z K= T/b <br /> Where: <br /> r-� K= hydraulic conductivity ; <br />'. T =transmissivity i <br /> S = storativity I <br /> Q = constant ground water pumping rate = 5.0. GPM. <br /> As = draw-down per 1-logarithmic cycle (Appendix H) = 0.92 ft. 4 <br /> t =time of pump test (Appendix G) = 720 minutes <br /> li h <br /> ro = intercept of best fit line with the distance axis (Appendix H) — 100 feet <br /> L b= aquifer thickness (semi penetrated or exposed screen length) <br /> 18 October 2001 <br /> T = 70 (5 gpm) / 0.92 feet = 380 feet' /day or <br /> 380 feet` /day (1 gal day/ft/0.134 feet'/day) = 2,840 gal day/feet j <br /> S = 380 feet' /day(720 minutes) /640 (100 feet)2 = 0.043 j <br /> K= 2,840 gal day/feet 130 feet = 94 feet/day <br /> K= 94 feet/day (lcm/sec/2835 feet/day) = 0.033 crn/sec <br /> r <br /> Advanced GeoEnvironmental Inc. <br />