ARCHIVED REPORTS_XR0006921- CASE 2

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Site Background Information Five e Star Marina Page 2 of 3 UST Hydrocarbon odors were not observed in soil above 11 feet bsg Approximately 5 cubic yards of hydrocarbon-impacted soil were removed and stockpiled during the UST excavation Soil samples were collected 2 feet below the UST, at depths of 12 feet bsg The overburden soil was used to backfill the lowest portion of the excavation ' Analytical results of soil samples collected from th yt p e UST excavation indicated that an unauthorized release of hydrocarbons had occurred at the western edge of the UST Total petroleum hydrocarbons quantified as gasoline(TPH-g)were detected in sample TI-W at 690 mg/kg 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 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 micrograms per liter(gg/1)to 44,000µg11 Various BTEX compounds were detected in six often samples analyzed at concentrations ranging from 0 60 µg/1 to 7,800 ggA ' Hydrocarbon-impacted soil in the vadoseunsaturated associated with the West UST area ( } zone, ea within Sari Jose Street,was limited to a narrow zone from depths of approximately 5 feet to 15 feet Ibsg 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 20 years iGasoline-Impacted groundwater 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 µg/1 from four of five grab ground water samples analyzed from the western property boundary The subject property has no documented use of TPH-d To determine the lateral extent of the hydrocarbon impact to soil and ground water associated with . the West UST, and the potential impact from the Texaco facility to the subject property, additional soil probe borings were advanced at the site under the supervision of the EHD Hydrocarbon- Advanced GeoEnviroomental,Inc