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10 September-2001 <br /> AGE-NC Project No. 98-0497 <br /> Page 2 of 5 <br /> 2.37. PREVIOUS.INVESTIGATIONS - <br /> On 29 September 19 99,two soil probe borings(P-1 acid 2)were advanced at the site as part of site, <br /> assessment activities related to the two former USTs..T e field work was conducted as outlined in <br /> the'PHS-EHD approved work pian dated 05 August 999. A.total -of seven soil. samples were <br /> submitted to-a DHS-certified laboratory for,analysis. TP -g was detected in soil samples collected <br /> from probe boring P-1 at concentrations ranging as high 1,900 mg/kg;--the laboratory reported the <br /> sample, chromatogram to be representative of a stro gly'aged- gasoline and that diesel range <br /> compounds were significant. TPH-d° .was detected -in soil samples collected- from P-1 at <br /> concentrations ,ranging as high, as 1"0,000 mg/kg the laboratory- reported the diesel range <br /> chromatograms as unmodified or weakly modified. Further.laboratory review of the gasoline and <br /> diesel range chromatograms indicated the sample chro tograms oto be more indicative;of a diesel <br /> impact. - <br /> BTEX compounds were detected in soil-samples collected from P-1 at concentrations ranging as high " <br /> as 8.3 mg/kg;" benzene was detected in-the P-1 sampl at 65 ,feet bsg, and was-quantified at a <br /> concentration of 0.047 rng/kg. MTBE was detected in soil samples collected from P-1 utilizing EPA <br /> Method 8260 modified at concentrations ranging.as high as 0.055-mg/kg.'No other fuel oxygenated <br /> compounds were detected during the laboratory'analysi of selected'soil samples. <br /> " .Ori 14 and.- S August 2000,four soil borings(P-3;MW- ',MW-2,MW-3)were advanced at the site. <br /> Borings MW-1. through MW-3,w ere.completed as gro und water.monitoring wells. Soil samples <br /> collected from the four borings did not contain -detectable concentrations of TPH-g.­ BTEX- <br /> compounds were-detected in samples P3=75 and MW1= 5 at concentrations of 0.018 milligrams per <br /> kilogi am(mg/kg) and 0:025 mg/kg,,respectively(xylen s).-TP.H-d was detected in soil samples P3'7 <br /> 100 and MW1-75 at concentrations of 7-8 mg/kg and 40mg/kg, respectively;which probably nearly <br /> defines the vertical extent ofimpacted soil..No oxyge ated compounds, EDB or 1,2-DCA were <br /> detected in the soil:samples analyzed. Petroleuin hydrocarbon compounds were not detected,in soil <br /> samples collected from soil boririgs MW-2 acid MW-3, 1'• 'ting the northern and southern extent of <br /> contamination in soil. Table 2 contains analytical results of soil samples collected'during soil baring <br /> advancement. Figures 3-and 4 illustrate the inferred vertical,and;horizontal extent of petroleum . <br /> hydrocarbon contamination at the site. <br /> -Quarterly monitoring of the ground water monitoring ell network has been performed at the-site <br /> since.the third quarter 2000. TPH=g and TPH-d have. een detected in monitoring well MW-1 at" <br /> concentrations as high as'5,7.00 µg/l and 120;000 µ , respectively. Minor concentrations of <br /> ethylbenzene and xylene have been detected sporadic y' in samples collected from MW-1. No <br /> chemicals of concern have been detected in monitorin "wellsMW-2 and MW-3 since monitoring <br /> began,limiting the northern and southern extent of pet.rc leum hydrocarbon contamination in ground <br /> Advanced GeoEnvironment4 Inc. <br />