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si,dewalla of the UST excavation were reportedly stained and had a distinct hydrocarbon odor , Soil overlying and sur-roundinq the UST' was temporarily- stockpiled adjacent to the UST excavation. A total of four soil samples saere c0.1lected, from the UST excavation. one sample was collected frora the native- soil at a depth of approximately 1 to 2 feet below each end of the USS' or the _4quivalent of approximately 11 feet below the existing ground surface {bgs} ; and two soil samples were collected from the central portion of the UST excavation at a depth of approximately 11 feet bqs. One grab water sample was also collected from the grounclwater that was encountered at the bottom of the UST excavation. Two additional soil samples were ao;.lected beneath the tank piping 'at a depth of approximately 3 feet bgs. Finally, two composite soil samples were collected from the stoc-kpiled. material._ so�.l samples collected beneath the UST and stockpiled material indicated lora to non-detectable concentrations of TPH as gasoline (TPdg) ; benzene--toluene^Pthylbenzene-xylenes (WrEX) ; oxygenates; and lead; and non-detectable to .elevated c�jncentratior.s of TPH as diesel (TPHd) . The grab groundwater sample collected from 'the UST excavation contained non-detectable concentrations of TPHg, BTEX, oxygenates, and lead; and an elevated concentration of TPHd. The soil samples collected beneath the. tank piping contained no concentrations of TPffg, TFHd, BTEX, oxygenates, anti lead. The approximately 687 tens of stockpiled petroleum-affected material containing the elevated concentration of TPHd .was disposed at f.'orwazd Laildfill (Forward) .in Manteca, California. ICES conducted a preliminary site investigation in March 2005. The. purpo4e of the in,%restigation was to define the extent of the petroleum- affected soil and groundwater in the vicinity of the former 10, Q0Q-gallon UST within the Site. Based on the laboratory analytical rr=sukts of the investigation, it appeared that .surfici.al soil Containing elevated concentrations of TPFid and TPHno klas limited to the' former UST pit at depths raxlging. from approximately 20 to 35 feet - bga. The une3erlying sediments and groundwater surrounding the' former UST pit in the easterly, and westerly direction was not impacted by petroleum constituents. A supplementax-y soil and groundwater investigation was performed by ICES in May 2006. The purpose of the investigation was to construct three monitoring wells within the approximate vicinity of the formez UST pit to monitor the. residual, petroleum hydroca.rbor, concentrations detected in the surficial soil and groundwater founct - 2