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I <br />' 20 March 2006 <br /> • AGE-NC Project No 95-0130 <br />' Page 9 of 13 <br /> 1 <br /> 41 GROUND WATER EXTRACTION-TREATMENT OPERATION <br />' During the fourth quarter 2005, extraction wells EW-1, EW-2,VW-IC,VW-2A and VW-3A were <br /> each adjusted at the well-heads to continuously extract ground water at a combined flow rate of <br />' approximately 1-2 GPM, however, due to ground water draw-down issues at EW-1 and EW-2, <br /> electric timers were installed to cycle pump operations at alternating I-hour intervals All extracted <br /> groundwater from EW-1,EW-2,V W-I C,V W-2A and VW-3A was routed from the extraction wells <br />' to a 5,000-gallon holding tank, from the holding tank, water was treated by passing through a low <br /> profile air stripper, then through four 2,000 pound media vessels containing liquid phase granular <br /> activated carbon (GAC) Following treatment, water was discharged underground via 1-inch <br />' diameter PVC piping to the City of Stockton sewer system,discharge piping is connected to a sewer <br /> clean-out located in a east section of the site, approximately 100 feet east-northeast of the P&T <br /> system <br />' Based on effluent flow meter readings (Table 9), approximately 174,065 gallons of treated water <br /> were extracted, treated and then discharged to the City of Stockton sewer system between <br /> • 07 September and 06 December 2005 under City of Stockton Department of Utilities Ground Water <br /> Discharge Permit (dated 1 I August 2003) <br />' <br /> 42 GROUND WATER EXTRACTION-TREATMENT SAMPLING PROCEDURES <br /> Ground water extraction and treatment influent,intermediate(AFT-AS)and effluent water samples <br /> were collected on a monthly basis from valved ports located upstream(influent),after the air stripper <br />' (intermediate, AFT-AS) and downstream (effluent) of the treatment unit The grab water samples <br /> were collected utilizing 40-m1 EPA-approved VOA vials containing 0 5 ml 18%hydrochloric acid <br /> as a sample preservative and 1-liter amber bottles Care was taken to ensure that visible air bubbles <br />' were not present in the vials after filling and capping Ground water sample containers were labeled <br /> with a sample designation, date, time, and sampler's initials <br />' 43 LABORATORY ANALYSIS OF GROUND WATER EXTRACTION AND TREATMENT <br /> Influent, intermediate(AFT-AS)and effluent grab water samples were logged on a chain of custody <br /> form, placed in a chilled container and transported to a California Department of Health Services <br /> (DHS)-certified laboratory to be analyzed for <br />' Totalp etroleum hydrocarbons as diesel and motor oil(TPH-d and TPH-mo),TPH-g,by EPA <br />' Advanced GeoEnvoronmental,Inc <br />