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' 30 March 2005 AGE-NC Project No 95-0130 ' Page 8of13 ' 41 GROUND WATER EXTRACTION-TREATMENT OPERATION During the fourth quarter 2004, extraction wells EW-1 and EW-2 were each adjusted at the well- Iheads to continuously extract ground water at a combined flow rate of approximately 2-3 GPM During the fourth quarter,all extracted ground water was routed from the extraction wells to a 5,000- gallon holding tank, from the holding tank, water was treated by passing through a low profile air stripper, then through four 2,000 pound media vessels containing liquid phase granular activated carbon (GAC) Following treatment, water was discharged underground via 1-inch diameter PVC I piping to the City of Stockton sewer system, discharge piping is connected to a sewer clean-out located in a east section of the site, approximately 100 feet east-northeast of the pump-and-treat system Based on effluent flow meter readings(Table 1),approximately 3 5,360 gallons of treated water were continuously extracted, treated and then discharged to the City of Stockton sewer system between 17 November 2004 to 29 December 2004 under City of Stockton Department of Utilities Ground Water Discharge Permit (dated 11 August 2003) 4 2 GROUND WATER EXTRACTION-TREATMENT SAMPLING PROCEDURES rGround water extraction and treatment influent,intermediate(AFT-AS)and effluent water samples were collected on a monthly basis from valved ports located upstream(influent),after the air stripper I (intermediate, AFT-AS) and downstream (effluent) of the treatment unit The grab water samples were collected utilizing 40-m1 EPA-approved VOA vials containing 0 5 ml 18% hydrochloric acid as a sample preservative and 1-liter amber bottles Care was taken to ensure that visible air bubbles ' were not present in the vials after filling and capping Ground water sample containers were labeled with a sample designation, date, time, and sampler's initials ' 43 LABORATORY ANALYSIS OF GROUNDWATER EXTRACTION AND TREATMENT Influent, intermediate(AFT-AS)and effluent grab water samples were logged on a chain of custody form, placed in a chilled container and transported to a California Department of Health Services (DHS)-certified laboratory to be analyzed for I • Total petroleum hydrocarbons quantified as gasoline, diesel and motor oil (TPH-g, TPH-d , and TPH-mo, respectively) by EPA Methods 35501503018015 Modified, • • Benzene, toluene, ethylbenzene and xylene (BTEX), tertiary butanol (TBA), di-isopropyl ether(DIPE), ethyl tert butyl ether(ETBE), tert amyl methyl ether(TAME) and methyl tert Advanced GeoEnvironmental,Inc I