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Appendix A
<br /> AGE NC Project No 99-0570
<br /> Page 2of5
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<br />' UNDERGROUND STORAGE TANK REMOVAL
<br /> On 05 February 1998, one 10,000-gallon UST, one 8,000-gallon diesel UST, and one 8,000-gallon
<br /> I gasoline UST were removed from the site, the approximate locations of the former USTs, product
<br /> piping, and dispensers are shown of Figure 2 Soil samples were collected at the UST locations,
<br /> dispensers, and product lines Laboratory analytical results detected total petroleum hydrocarbons
<br />' quantified as gasoline and diesel (TPH-g and TPH-d), benzene, toluene, ethylbenzene, and total
<br /> xylenes (BTEX), and fuel additives in the soil samples collected from the UST excavations and
<br /> dispenser areas, the latter exhibited significant staining and hydrocarbon odor
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<br /> Only one UST removal sampling had detectable concentrations of hydrocarbons,yet all samples had
<br /> moderate detections of fuel additives High concentrations of hydrocarbons and low concentrations
<br /> of fuel additives were generally detected In soil samples D2, D3, and D5 from the former dispenser
<br /> areas The dispenser soil samples exhibited significant staining and hydrocarbon odor
<br /> IPREVIOUS SITE ASSESSMENT
<br /> rOn 11 August 1999,an additional 150 cubic yards of significantly petroleum hydrocarbon-Impacted
<br /> soil was removed from beneath the three former dispenser areas Laboratory analytical data Indicated
<br /> a significant concentration of TPH-g, TPH-d, BTEX compounds, and fuel additives in the soil
<br /> samples collected
<br />' On 29 October and 01 November 1999,AGE advanced eight soil probe borings to a depth of 30 feet
<br /> below surface grade (bsg) at the site to obtain soil and grab ground water samples TPH-g, TPH-d,
<br /> BTEX,and methyl tertiary-butyl ether(MTBE)were detected in soil samples analyzed at maximum
<br /> concentrations of 49 milligrams per kilogram(mg/kg), 180 mg/kg,0 36 mg/kg,and 78 micrograms
<br /> per kilograms(µg/kg),respectively Laboratory analysis of grab groundwater samples indicated that
<br /> the highest concentrations of TPH-g, TPH-d, BTEX, and MTBE were in the vicinity of the former
<br /> dispenser islands Based on the data collected,the dispenser islands appear to be the primary source
<br /> of the hydrocarbon release
<br /> Ground water monitoring wells MW-1 through MW-5 were installed On 27 and 28 September 2000
<br /> and monitored and sampled on 03 October 2000 TPH-g and TPH-d compounds were detected in a,i(y
<br /> only one of eleven soil samples, at similar concentrations of 170 mg/kg, in addition, BTEX and -�an.W�'
<br /> several additional volatile organic compounds were detected at concentrations up to 0 44 mg/kg n'at2 f
<br /> TPH-g,TPH-d,and BTEX we, aeecte n two ground water samples collected on 03 October 2000 is
<br /> at maximum concentrations of�g/l,YWgg/l,and 160µg/1,respectively,in addition,MTBE was
<br /> detected in three ground water samples at a maximum concentration of 170 µg/1 IV
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<br /> Advanced GeoEnvironmental,Inc.
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