SITE INFORMATION AND CORRESPONDENCE_FILE 2

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Site Background Information: Chapin Brothers Investments, Inc. Page 15 of 19 intake from any of the Grundfos pumps. Three 2,000-gallon media vessels, one 1,000-gallon poly holding tank, one process pump and one sediment filter chamber were installed for the ground water treatment system.Ground water pumped from the recovery wells is initially routed via the piping system to the 1,000-gallon holding tank prior to processing. The process pump is designed to process ground water through the treatment system at a maximum flow rate of 20 gallons per minute (GPM). The ground water was routed to the three 2,000 pound vessels containing granular activated carbon(GAC).The GAC media vessels are designed to adsorb TPH-g and BTEX compounds. Brass sampling ports were installed at the influent,between the media vessels and at the effluent to allow detection of potential media break through and to obtain final discharge samples.A F-2000 model RT Blue-White Industries flow meter was installed on the effluent line to continuously measure and display the effluent flow rate and to continuously measure and display the total flow. GROUND WATER TREATMENT OPERATION AND MONITORING The ground water treatment system is designed to operate at a maximum flow rate of up to 15 gallons per minute (GPM); therefore each of the three recovery wells was adjusted to extract ground water at a flow rate of approximately 5 to 6 GPM by extracting on an intermitting cycle.The operation of the pumps allow for up to a four minute hiatus interval, after which the pump will reactivate. This hiatus mainly allow for water level recharge within the wells. The ground water treatment system operates on a batch basis, with a daily total of 14,400 gallons. Once the 2,000- gallon holding tank fills, approximately 1,750 gallons of extracted ground water is treated and discharged.The discharge of treated water(effluent)to the City of Stockton was adjusted at a flow rate of approximately 15 GPM. Grab ground water samples were collected from the influent of each well and the effluent of the treatment system. Samples were collected in laboratory-supplied 40-m1 EPA-approved volatile organic analysis(VOA) vials containing 0.5 ml 18%hydrochloric acid as a preservative. Effluent samples were collected in the (VOA) vials, 1-liter amber bottles without preservative and 500- milliliter plastic bottles without preservative.The samples were analyzed for TPH-g,BTEX,MTBE, Volatile and Semi-volatile compounds (VOC and SVOC), Metals: Cd, Cr, Cu, Pb, Ni and Zn in accordance with EPA Method 200 Modified and pH. Dissolved hydrocarbon concentrations detected from ground water samples collected at the influent end of the treatment system generally declined over the remediation.The concentration of benzene detected in the influent treatment samples was reduced by an average of 70%,during the remediation period. Advanced GeoEnviron mental,Inc.