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Site Background Information/SCM Former MBP - Mo . ssdale AGE NC Project No 99-0570 ' Page 2 of 5 ' UNDERGROUND STORAGE TANK REMOVAL On 05 February 1998,one 10,000-gallon UST, one 8,000-gallon diesel UST, and one 8,000-gallon ' gasoline UST were removed from the site, the approximate locations of the former USTs, product piping, and dispensers are shown on Figure 2 of the attached report Soil samples were collected at the UST locations, dispensers, and product lines Laboratory analytical results detected total petroleum hydrocarbons quantified as gasoline and diesel (TPH-g and TPH-d), benzene, toluene, ethylbenzene, and total xylenes (BTEX), and fuel additives in the soil samples collected from the UST excavations and dispenser areas,the latter exhibited significant staining and hydrocarbon odor in Onl one UST removal sampling Y p g ha d detectable concentrations of hydrocarbons,yet all samples had moderate detections of fuel additives High concentrations of hydrocarbons and low concentrations ' of fuel additives were generally detected in soil samples D2, D3, and D5 from the former dispenser areas The dispenser soil samples exhibited significant staining and hydrocarbon odor Analytical ' results are summarized in Table l of this appendix PREVIOUS SITE ASSESSMENT • On 11 August 1999, three limited excavations in the northeast rt east edge of the former dispensers removed an estimated 150 cubic yards of significantly petroleum hydrocarbon-impacted soil The total depth of the three excavations was 8 feet bsg The sidewalls and floor of the excavations EXE2 and EXE3 exposed hydrocarbon-impacted soil Hydrocarbon-stained soil was not apparent in the final sidewalls and floor of excavation EXEI Soil samples were collected from the excavation side walls at a depth of 8 feet bsg and a soil sample was collected from the floor of the southernmost excavation (EXEI) at a depth of 8 feet bsg The analytical data indicated that the highest concentrations of TPH-g were in excavations EXE2 and EXE3 at the northeastern edge of the dispenser area, near well MW-2 TPH-g was detected in the eastern soil sample from excavation EXE2 at a concentration of 17,000 mg/kg TPH-g was also detected in the soil sample from the ' southern edge of excavation EXE3 at a concentration of 11,000 mg/kg BTEX compounds were detected at concentrations as high as 2,300 mg/kg The highest concentration of benzene, 15 mg/kg, was detected in the eastern sample from excavation EXE2 Fuel additives were detected in samples ' from excavations EXE2 and EXE3 TPH-d was detected in the soil samples from EXE2 and EXE3, which were also impacted with TPH-g and BTEX compounds Low concentrations of TPH-d were detected in two soil samples from EXEI The stockpiled soil was impacted by low to moderate ' concentrations of petroleum hydrocarbons and fuel additives The results are summarized in Table 1 of this appendix IOn 29 October and 01 November 1999,AGE advanced eight soil probe borings to a depth of 30 feet below surface grade(bsg) at the site to obtain soil and grab ground water samples TPH-g, TPH-d, BTEX,and methyl tertiary-butyl ether(MTBE)were detected in soil samples analyzed at maximum J Advanced GeoEnvironmental,Inc