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1 <br /> ' 24 June 2005 <br /> • AGE-NC Project No 95-0103 <br /> Page 2 of 12 <br /> ' within each well Due to the low flow recharge within the extraction wells and aged conditions of <br /> the majority of the ground water pumps, the typical operational cycle for the pumps has been <br /> diminished,caused circuit protection faults over time and reduced the total volume of ground water <br /> extracted <br /> Extracted ground water was routed through a ground water treatment system consisting of granular <br /> activated carbon (GAC) Following treatment, water was discharged' underground via 1-inch <br /> diameter poly vinyl chloride (PVC) piping to the City of Stockton sewer system <br /> Effluent flow meter readings utilizing a Blue-White Industries F-2000 flow meter recorded <br /> ' 219,928 gallons of water treated and discharged to the City of Stockton sewer system under permit <br /> during the first two quarter of 2005 The ground water treatment system operates on a batch basis, <br /> ' with a dally total of approximately 2,500 gallons Once the holding tank fills with approximately <br /> 750 gallons of extracted ground water, the system cycles and the water is treated and discharged <br /> The discharge of treated water (effluent) to the City of Stockton was adjusted at a flow rate of <br /> ' approximately 10 GPM The ground water extraction system ceased operation on 10 May 2005, as <br /> approved in the Ground Water Monitoring-Natural Attenuation Work Plan dated 21 March 2005 <br /> r• <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 Treatment-system grab ground water <br /> samples were collected monthly,either from extraction wells EW-1, EW-2, EW-3 and in addition, <br /> a monthly ground water sample was collected from the effluent stream of the system <br /> ' Influent samples were collected in laboratory-supplied 40-milliliter (mi) EPA-approved volatile <br /> organic analysis (VOA) vials containing 0 5 ml 18% hydrochloric acid as a preservative Effluent <br /> samples were collected in the VOA vials, l-liter amber bottles without preservative Care was taken <br /> to ensure that visible air bubbles were not present in the vials after filling and capping Water sample <br /> containers were labeled with the sample designation, date, time, and sampler's initials <br /> The samples collected were logged on a chain-of-custody form, placed in a chilled container and <br /> transported to Cal Tech Environmental Laboratories,Inc (CTEL)a California Department of Health <br /> ' Services (DHS)-certified laboratories, for analysis 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 total xylene (BTEX) and the fuel additive methyl <br /> Advanced GeoEnvironmental,Inc <br />