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• 31 October 2003 <br /> AGE-NC Project No 95-0103 <br /> ' Page 2 of 7 <br /> ' to the City of Stockton sewer system under permit during the second and third quarters 2003 (Table <br /> 4) The ground water treatment system operates on a batch basis, with an average daily total of <br /> 3,363 gallons Once the 2,000-gallon holding tank is filled,approximately 1,500 gallons of extracted <br /> ' ground water is treated and discharged <br /> The discharge of treated water(effluent) to the City of Stockton had been reduced due to fouling of <br /> ' the carbon media, with a maximum flow rate of approximately 3 5 gpm <br /> 2 2 GROUND WATER TREATMENT MONITORING PROCEDURES <br /> ' In order to verify and quantify the mass of contamination from each extraction well and to comply <br /> with the requirements of the City of Stockton discharge permit, monthly monitoring and sampling <br /> of influent and effluent ground water samples were performed Grab ground water samples were <br /> ' collected on 15 April,21 May, 15 June, 21 July 19 August and 19 September 2003 from extraction <br /> wells EW-1, EW-2, EW-3 and VW-6 through dedicated sampling ports at the inlet to the <br /> remediation system holding tank and the effluent port ofthe treatment system on all sampling events <br /> 10 Influent samples were collected in laboratory-supplied 40-m1 EPA-approved volatile organic analysis <br /> (VOA) vials containing 0 5 ml 18% hydrochloric acid as a preservative Effluent samples were <br /> collected in the OA vials, l-liter amber bottles without preservative and 500-milliliter plastic bottles <br /> ' without preservative Care was taken to ensure that visible air bubbles were not present in the vials <br /> after filling and capping Water sample containers were labeled with the sample designation, date, <br /> time, and sampler's initials <br /> The samples collected were logged on achain-of-custody form, placed in a chilled container and <br /> transported to Cal Tech Environmental Laboratories, Inc (CTEL) or McCampbell Analytical Inc <br /> ' (MAI) a California Department of Health Services (DHS)-certified laboratories, for analysis <br /> Samples were analyzed for <br /> ' • Total petroleum hydrocarbons quantified as gasoline (TPH-g) by EPA Method 8015 <br /> Modified, and <br /> ' • Benzene,toluene,ethyl benzene and xylene(BTEX)and methyl-tertiary butyl ether(MTBE) <br /> by EPA Methods 8020 or 8260 <br /> i <br /> ' In addition, the effluent samples were analyzed for pH in accordance with EPA Method 150 1 and <br /> total petroleum hydrocarbons quantified as diesel (TPH-d) by EPA Method 8015 Modified <br /> 1 <br /> • <br /> Advanced GeoEnvironmental,Inc <br />