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1 <br /> Site Background Information Five Star Marina <br /> ' Page 2 of 3 <br /> UST Hydrocarbon odors were not observed in soil above 11 feet bsg Approximately 5 cubic yards <br /> of hydrocarbon-impacted soil were removed and stockpiled during the UST excavation Soil samples <br /> were collected 2 feet below the UST, at depths of 12 feet bsg The overburden soil was used to <br /> ' backfill the lowest portion of the excavation <br /> Analytical results of soil samples collected from the UST excavation indicated that an unauthorized <br /> release of hydrocarbons had occurred at the western edge of the UST Total petroleum hydrocarbons <br /> quantified as gasoline(TPH-g)were detected in sample T 1-W at 690 mg/kg TPH-g was not detected <br /> in the soil sample collected from the eastern end of the UST <br /> PREVIOUS SITE INVESTIGATION <br /> ' On 14 November 1996 and 16 January 1997, a total of fifteen soil probe borings (P1 through P15) <br /> were advanced at the site under the supervision of the EHD Soil probe borings were advanced in <br /> ' the vicinity of the West UST area at the western edge of the site and in the vicinity of the on-site <br /> plating shop Locations of the soil probe borings are illustrated on Figure 2 <br /> '• TPH-g,BTEX,and methyl tertiary-butyl ether(MTBE)were detected in soil samples collected from <br /> the probe borings at concentrations as high as 3,700 mg/kg Hydrocarbon-impacted soil associated <br /> with the West UST area appeared to be of limited lateral extent TPH-g was detected in four of ten <br /> grab ground water samples collected from the West UST area at concentrations ranging from <br /> 84 micrograms per liter(µg/l)to 44,000 gg/l Various BTEX compounds were detected in six of ten <br /> tsamples analyzed at concentrations ranging from 0 60 gg/l to 7,800 gg/l <br /> ^" <br /> Hydrocarbon-impacted soil in the vadose unsaturated zone associated with the West UST area <br /> (unsaturated) <br /> within San Jose Street,was limited to a narrow zone from depths of approximately 5 feet to 15 feet <br /> bsg immediately surrounding the UST The detection of MTBE in soil samples collected from probe <br /> boring P 1 indicated the release of gasoline to be relatively recent,possibly within the past 20 years <br /> Gasoline-impacted ground water is present around the West UST area The dissolved gasoline plume <br /> appears to extend to approximately 50 feet northeast and 50 feet southwest from the former West <br /> UST area, and has an approximate width of 40 feet <br /> Total petroleum hydrocarbons quantified as diesel (TPH-d) was detected at concentrations up to <br /> ' 6,600 gg/1 from four of five grab ground water samples analyzed from the western property <br /> boundary The subject property has no documented use of TPH-d <br /> ' To determine the lateral extent of the hydrocarbon impact to soil and ground water associated with <br /> the West UST,and the potential impact from the Texaco facility to the subject property, additional <br /> soil probe borings were advanced at the site under the supervision of the EHD Hydrocarbon- <br /> Advanced GeoEnvtron mental, <br /> ydrocarbon- <br /> AdvancedGeoEnvtronmental,Inc <br />