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V 4 <br /> Mr. Michael Walton � <br /> Walton Engineering <br /> March 20, 1998 <br /> Laboratory analytical results of the soil sample composites collected from the soil stockpile indicated <br /> that elevated concentrations of TPHg and BTEX compounds and/or TPHd were detected in all four <br /> of the soil sample composites (Table 2). Total lead was detected at concentrations slightly greater <br /> than the reporting limit of the laboratory method in all four soil sample composites (Table 2). <br /> TABLE 2 <br /> LABORATORY RESULTS OF SOIL SAMPLE ANALYSES <br /> OVEREXC AVATION AND SOIL STOCKPILE <br /> 3300 WEST LANE, STOCKTON, CALIFORNIA <br /> t EthI- Totals'T Fotai <br /> Sa pl�l`iumhet' TPH� ,Benzene Toluene. EHd d- <br /> v hen <br /> "C <br /> zene <br /> Overexcavation <br /> S-19-E 1 n -/<1.0 ✓<0.005 <0.005 <0.005 <0.010 /29 1.0 na <br /> na <br /> S-17-Elw `' <1.0 '/ <0.005 <0.005 <0.p05 <0.010 ✓ <br /> 230 na <br /> S-24-E1b 1.4 1<0.005 <0.005 <0.005 0.011 j 23 <br /> Soil Stockpiles <br /> SPla-d ✓2.4 0.0087 0.290 0.130 0.950 na 71 <br /> SP l e-h ✓ 1.3 ✓<0.005 0.023 0.0096 0.140 na 8.8 <br /> SP'a-d 9.3 ✓0.0071 0.110 0.120 0.930 ✓780 11 <br /> SP'e-h s 65 L'-'<0.050 0.120 1.20 3.60 ✓14,000 12 <br /> Laboratory results of soil samples are reported in milligrams/kilogram(parts per million) <br /> TPHg=Total Petroleum Hydrocarbons in the range of gasoline <br /> TPHd=Total Petroleum Hydrocarbons in the range of diesel fuel <br /> <=Less than the laboratory method reporting limit <br /> na=not analyzed <br /> DISCUSSION <br /> In November of 1997, the Regional Water Quality Control Board issued a mandate requiring that <br /> environmental samples collected from underground storage tank sites be analyzed for five prominent <br /> gasoline oxygenates and that this analytical data would be a criteria necessary for site closure. The <br /> representative from SJCEHD requested,therefore,that all of the soil samples collected from beneath <br /> underground storage tanks and fuel dispenser islands at the site be analyzed for the five oxygenates. <br /> These five compounds include di-isopropyl ether(dIPE), ethyl t-butyl ether(EtBE), methyl t-butyl <br /> ether (MtBE), t-amyl methyl ether(tAME), and t-butyl alcohol (tBA). <br /> A total of thirteen soil samples collected from the site were analyzed for the five oxygenates. Only <br /> the soil samples collected from beneath the northern ends of the fuel dispensers contained elevated <br /> concentrations of gasoline oxygenates. The soil sample collected from approximately 4 feet below <br /> ground surface at sample location FD 1 contained 2.5 ppm tBA and 0.11 ppm MtBE; the soil sample <br /> GRA YLAND ENVIRONMEVT.4L <br /> Gravland 022-t 60.trr 6 <br />