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TECHNICAL APPROACH SUMMARY The objectives of this proposed scope of work are to further define the extent of soil contamination and to determine if groundwater is impacted beneath the site. To achieve these objectives , soil and groundwater samples will be collected for laboratory analysis from 3 Geoprobe soil borings. The three borings will be located at the south ends of both former USTs and adjacent to the former dispenser island . Soil samples previously collected from these locations exhibited the highest concentrations of gasoline hydrocarbons. Each soil boring will be advanced to the groundwater table at a depth of approximately 35 feet. During drilling , soil samples will be collected at five-foot intervals for logging , field screening with a PID , and possible laboratory analysis. From each soil boring , a groundwater sample will be collected through the rods of the Geoprobe. Prior to groundwater sampling , groundwater from each of the borings will be hand purged . The volume of groundwater purged will depend on the strength of groundwater recharge. Following purging , groundwater samples will be collected from the borings using a bailer. Each of the soil borings will be abandoned using neat cement grout. The boreholes will be filled with grout from the bottom using a tremie pipe. Following borehole abandonment, the surface pavement will be restored . Based on field observations and PID measurements, approximately three soil samples per boring and all of the groundwater samples will be submitted for laboratory analysis. Additional soil samples may be submitted for analysis, if required to adequately characterize the site. Field observations and sample selection will be reviewed with the PHS/EHD inspector, prior to sample submittal to the lab . Each soil and groundwater sample will be analyzed for Total Petroleum Hydrocarbons (TPH)-as- gasoline, benzene, toluene, ethylbenzene, xylenes (BTEX) , methyl tertiary butyl ether (MTBE) , di- isopropyl ether (DIPE) , ethyl tertiary butyl ether (ETBE) , tertiary amyl methyl ether (TAME) , and tertiary butanol (TBA) by EPA Method 8260B , and for TPH-as-diesel , TPH-as-motor oil and TPH- as-kerosene by EPA Method 8015M . The soil samples collected from the soil boring adjacent to the former dispenser will also be analyzed for total lead by EPA Method 6010 . All laboratory analyses will be performed on standard turn-around . Results of the proposed work will be documented in a Preliminary Investigation and Evaluation Report (PIER) . The PIER will be prepared and stamped by a state of California Registered Geologist. Copies will be submitted to PHS/EHD and RWQCB . The PIER could be submitted as early as November 2000. 3