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1 <br />' 10 December 2001 <br /> AGE NC Project No 95-0143 <br />' Page 9 of 10 <br />' 6 36 feet was observed in extraction well EW 3 following approximately 8 hours of pumping <br /> operation, ground water draw-down was observed in each of the observation wells ranging <br /> from 0 72 feet (EW-4 located approximately 10 feet north of EW-3) to 0 12 feet (MW-9 <br /> located approximately 140 feet north--northwest of EW-3) Draw-down results are presented <br /> on Table 4, Figure 2 illustrates well locations <br />' • Utilizing a sewn-loganthmic plot of ground water draw-down vs observation well distance <br /> to pumping well(Jacob straight-line method), a best-fit Ilne can be utilized to project a radius <br /> of influence of approximately 160 feet at 8 gpm(Appendx K) <br />' • Utilizing the Distance-Drawdown Method(Jacob straight-line method), a transrnassivity was <br /> calculated at 1,120 W/day (equivalent to 8,360 gallons per day/ft) and a storahvity value <br />' calculated at 0 099 (Apendax�) <br /> • Based on a transnussivity value of 1,120 ft'/day and an aquifer thickness equal to 20 ft <br /> (scream interval at EW-3), a hydraulic conductivity value was calculated at 418 ft/day, or <br /> 9X47 cm/s (Appendix K), a hydraulic conductivity of 0 147 cm/s is consistent with a <br /> screened interval located within clean sand (Appendix N) <br />' Laboratory analysi of extracted water duruig the pumping test detected elevated <br /> concentrations of TPH-g and BTEX compounds (Table 3, Appendices C and L) <br /> I <br /> 5.0. RECOMMENDATIONS <br /> iBased on the ground water aquifer pumping test results, AGE recommends extracting petroleum- <br /> impacted groundwater from EW-3 and EW-4 at approximately 8 gpm, based on the site's estimated <br /> radius of influence on the order of 160 feet and site specific aquifer characteristics inferred from the <br /> pumping test,AGE believes that ground water extraction from the two wells will effectively address <br /> the contaminated ground water plume and inhibit further migration of petroleum-impacted ground <br /> water off-site <br /> Extracted ground water from EW-3 and EW-4 could be pumped directly through an on-site ground <br />' water pump-and-treat system The ground water pump-and-treat system would utilize granular <br /> activated carbon (GAC) to address TPH-g and BTEX in extracted ground water Fallowing <br /> treatment, water could then be discharged into the City of Stockton sewer system under a City of <br /> Stockton Public Works permit <br /> IAdvanced GeoRnviranuiental,Inc <br />