ARCHIVED REPORTS_REPORT OF ADDITIONAL SOIL AND GROUNDWATER INVESTIGATION

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•yam GEOMATMIX • petroleum hydrocarbons and no petroleum hydrocarbons were detected in the samples(Earth System ' Consultants, 1999a). On July 29, 1999 ESC advanced six soil borings along the northern property boundary of the site (borings EB-lb through EB-6;Figure 2). Petroleum hydrocarbon-affected soil was observed in two of these borings(EB-2 and EB-3). Soil samples were collected from borings EB-2 and EB-3 at depths of 11.5 and 11 feet bgs,respectively. No petroleum hydrocarbon affected soil was observed in borings EB-1,EB-4,EB-5,and EB-6 and therefore no soil samples were collected from these ' borings for analysis. Total petroleum hydrocarbons(TPH)quantified as crude oil(TPHc)and polynuclear aromatic hydrocarbons(PAHs)were detected in the soil samples collected from borings ' EB-2 and EB-3 (Earth Systems Consultants, 1999b). Results from ESC's July 1999 investigation are summarized in Table 1. Based on these findings,Geomatrix advanced seven soil borings(GMX-9 through GMX-12 and GMX-20 through GMX-22;Figure 2)at the site on September 23 and 24, 1999. Petroleum hydrocarbon affected soil was observed in three borings(GMX-9, GMX-10,and GMX-12)between depths of 7 and 14 feet bgs. A soil sample was collected from the most visibly affected portion of the soil core. TPHc was detected in soil samples collected from these three borings at concentrations between 9900 and 14,000 milligrams per kilogram(mg/kg). TPH quantified as diesel(TPHd)and TPH quantified as gasoline(TPHg)were detected at concentrations ranging from 3900 to 5600 ' mg/kg and 32 to 200 mg/kg,respectively. Based on review of the chromatograms,it appears that these samples are impacted by degraded crude oil and the TPHg and TPHd results are simply portions of the crude oil boiling range. A forensic evaluation of the soil sample collected from boring GMX-12 indicated that the petroleum hydrocarbons present in the sample likely represent degraded crude oil. Benzene,toluene, ethylbenzene,xylenes(BTEX),and methyl tertiary butyl ether(MTBE) were not detected in any of the soil samples from these three borings. Low concentrations of several PAHs were detected in the soil samples from GMX-9 and GMX-10. To confirm the lateral extent of affected soil,a confirmation sample was collected directly above the ' water table(approximately 10.5 to 12 feet bgs)from the four borings advanced outside of the area of visibly affected soil(GMX-11, GMX-20,GMX-21,and GMX-22). All samples were analyzed for TPHc,TPHd,TPHg,BTEX,MTBE and PAHs;no analytes were detected in these samples. Soil analytical results from Geomatrix's September 1999 investigation are summarized in Table 1. ' A grab groundwater sample was collected from just beneath the affected soil in boring GMX-12. This sample was analyzed for BTEX,MTBE, and PAHs. No BTEX or MTBE were detected in the \\SF3\DEPTDATA\DOC_SAFE\60005\6115.007\DEC2000REPORT\BURNS SOILGW RPTNOV00 1.DOC 2