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I 02 June 2005 • AGE-NC Project No 95-0130 IPage 8 of 13 41 GROUND WATER EXTRACTION-TREATMENT OPERATION During the first quarter 2005,extraction wells EW-1 and EW-2 were each adjusted at the well-heads I to continuously extract ground water at a combined flow rate of approximately 2-3 GPM,however, due to ground water draw-down issues at EW-1,an electric timer was installed to cycle EW-1 on and off at 1-hour intervals IDuring the first 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 I air stripper,then through four 2,000 pound media vessels containing liquid phase granular activated carbon (GAC) Following treatment, water was discharged underground via I-inch diameter PVC piping to the City of Stockton sewer system, discharge piping is connected to a sewer clean-out Ilocated 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 81,280 gallons of treated water were extracted, treated and then discharged to the City of Stockton sewer system between 29 December • 2004 to 08 March 2005 under City of Stockton Department of Utilities Ground Water Discharge Permit (dated 11 August 2003) 4 2 GROUND WATER EXTRACTION-TREATMENT SAMPLING PROCEDURES Ground 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 (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 C43 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 • Total petroleum hydrocarbons as diesel and motor oil(TPH-d and TPH-mo),TPH-g,by EPA Methods 3550/5030/8015 Modified and Advanced GeoEnvironmental,Inc I