ARCHIVED REPORTS_XR0006922-CASE 2

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Site Background. g ound Information Five Star Marina Page 2 of 3 The UST was located in Lindsay Street, between the northern and southern blocks of buildings ' Upon removal of the UST, holes were noted at the western end and in the bottom of the UST Hydrocarbon odors were not observed in soil above eleven feet below surface grade (bsg) Approximately five cubic yards of hydrocarbon-impacted soil were removed and stockpiled during the UST removal Soil samples were collected from two feet below the UST,at depths of twelve feet bsg The overburden soil was used to back fill the lowest portion of the excavation ' Analytical results of soil samples collected from the UST excavation indicated that an unauthorized release of hydrocarbons had occurred at the western edge of the UST Total petroleum.hydrocarbons ' quantified as gasoline were detected in sample T1-W at 690 mg/kg Total petroleum hydrocarbons quantified as gasoline (TPH-g) was not detected in the soil sample collected from the eastern end of the UST PREVIOUS SITE INVESTIGATION On 14 November 1996 and 16 January 1997, a total of fifteen soil probe borings(P 1 through P 15) were advanced at the site under the supervision of the EHD Soil probe borings were advanced in '• the vicinity of the West UST area at the western edge of the site and in the vicinity of the on-site plating shop Locations of the soil probe borings are illustrated on Figure 2 Total petroleum hydrocarbons as gasoline(TPH-g),BTEX,and methyl tertiary butyl ether(MTBE) were detected in soil samples collected from the probe borings at concentrations as high as 3,700 mg/kg Hydrocarbon-impacted soil associated with the West UST area appeared to be of ' limited lateral extent TPH-g was detected in four of ten grab ground water samples collected from the West UST area at concentrations ranging from 84 to 44,000 µg11 (micrograms per liter or parts ' per billion ppb) Various BTEX compounds were detected in six of ten samples analyzed at concentrations ranging from 0 60 to 7,800 pg/l Hydrocarbon-impacted soil in the vadose (unsaturated) zone, associated with the West UST area within San Jose Street, was limited to a narrow zone from depths of approximately 5 to 15 feet bsg immediately surrounding the UST The detection of MTBE in soil samples collected from probe boring P 1 indicated the release of gasoline to be relatively recent, possibly within the past twenty years ' Gasoline-impacted ground water is present around the West UST area The dissolved gasoline plume appears to extend to approximately 50 feet northeast and 50 feet southwest from the former West UST area, and has an approximate width of 40 feet Total petroleum hydrocarbons quantified as diesel(TPH-d) was detected at concentrations up to 6,600 �ig/1 from four of five grab ground water samples analyzed from the western property Advanced GeoEnvironmentai,Inc