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2.3.2 SoH Excavation <br /> Review of historical site data have indicated that a UST tankpit excavation measuring <br />' approximately 17' x 5' x 14' (length x width x depth), was dug during the tank removal <br /> process in 1986 The excavation was subsequently backfilled to grade During the planned <br /> field effort, the existing tank excavation backfill will be removed and stockpiled using a back- <br /> hoe or an excavator Additional impacted soil will also be removed to a maximum volume of <br /> approximately 200 cubic yards <br /> During the excavation activities, the soil will be screened using a photoiomzation detector <br />' (PID) and initially sorted based on visual and measured petroleum hydrocarbon <br /> concentrations The excavation material will be stockpiled adjacent to the excavation on <br /> plastic sheeting and segregated as "clean" or "impacted" material. The excavated material <br /> will be covered with plastic sheeting at the end of each shift <br /> Once the backfill material has been removed, five soil samples will be collected from the <br /> sidewalls and bottom of the excavation and analyzed by an on-site mobile laboratory If <br /> laboratory analytical results indicate significant petroleum hydrocarbon impact, additional <br /> excavation will be conducted in an attempt to remove any residual impacted material The <br /> Mnative soils will be excavated until no visual, olfactory or field instrument indications of TPH <br /> concentrations remain, or the practical limits of the excavator have been reached Verification <br /> soil samples will be collected to monitor the effectiveness of this overexcavation A <br /> maximum of five additional samples will be collected. <br /> ' X511 <br /> Based on available analytical data, the bottom of the excavation will be at approximately <br /> twenty (20 feet below grade If any additional excavation is recommended based on field <br /> conditions, approval will be obtained by Van Den Bergh Foods and the County prior to any <br /> further activities Site conditions will also determine if shoring or sloping of the excavation <br /> ' will be required It is not anticipated that the integrity of any structures at the facility will be <br /> impacted by excavation activities. <br /> 2.3.3 Soil Characterization <br /> The soil samples collected during the excavation activities will be analyzed for TPH as <br /> gasoline and TPH as diesel using the modified EPA method 8015 and BTEX using EPA <br /> method 8020 An on-site mobile laboratory will be used to expedite the sample analyses. <br /> • M7J11-29-941UST/94-0201 nbr 4 <br />