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1 <br /> r <br /> Site Background Information - Ripon Farm Service <br /> Page 4 of 8 <br /> ' of 2,400 µg/1 and 130 µg11, respectively. TPH-d was detected in all three grab ground water <br /> samples at concentrations ranging from 210 gg/l to 5,400 µg11. Low concentrations of <br /> toluene, ethylbenzene, and xylenes were also detected in two of the three grab ground water <br /> rsamples. Neither benzene nor MTBE were detected in the grab ground water samples. <br /> TPH-d concentrations exceeded TPH-g concentrations in three of the eight soil samples analyzed, <br /> the remaining five soil samples did not contain detectable concentrations of either range of petroleum <br /> hydrocarbons. <br /> ' On 13 May 1998, five soil borings were drilled on-site (B18 and B19) and off-site (B20 through <br /> B22) with three off-site borings completed as ground water monitoring wells MW-6, MW-7, and <br /> MW-8; the two on-site borings were dual-completed as remediation pilot-test wells VW-1 and <br /> VW-2. Saturated soil conditions were encountered in all borings at a depth of approximately <br /> 17 feet bsg. <br /> ' TPH-g was detected in two out of eleven analyzed soil samples collected from borings B 18 <br /> through B21, BTEX was detected in five of the samples. The greatest concentrations of <br /> lie TPH-g and TPH-d detected were 440 mg/kg and 1,400 mg/kg,respectively, encountered in <br /> sample B 19-20. Toluene, ethylbenzene, and total xylenes were detected in the soil samples <br /> at concentrations as great as 8.6 mg/kg(xylenes).Oxygenated compounds were not detected <br /> ' in the soil samples analyzed. Volatile organic compounds (VOCs) were detected in soil <br /> samples collected at variable concentrations. <br /> • Soil samples collected from the Jimco Truck Stop at depths of 20 feet bsg were impacted <br /> with TPH-d at concentrations as high as 490 mg/kg, and xylenes at concentrations as high <br /> as 0.017 mg/kg. <br /> ' Naphthalene was detected at a concentration of 2,600 micrograms per kilogram(gg/kg).The <br /> VOC encountered at the greatest concentration in the soil samples was 1,3,5- <br /> trimethylbenzene, which was detected at a concentration of 12,000 µg/kg. <br /> r <br /> Quarterly monitoring events have been conducted at the site since the first ground water monitoring <br /> ' wells were installed. The general results of the ground water monitoring events are as follows: <br /> • TPH-g has been detected in groundwater samples collected from wells MW-1 though MW-8 <br /> at concentrations as high as 14,000 gg/l. TPH-d has been detected at concentrations as high <br /> as 12,000 µg/l. TPH-g has been detected in ground water samples collected from soil vapor <br /> wells (VW-1 and VW-2) at concentrations of 12,000 µg11 and 4,700 µg/1, respectively. <br /> ' • Benzene has been detected in the samples from wells MW-2,VW-1,and VW-2 at maximum <br /> concentrations of 1,400 gg/l,2,000µg/1,and 30µg/1,respectively.Toluene has been detected <br /> ' at a maximum concentration of 61 µg/1 in well VW-1. Ethylbenzene and xylenes have been <br /> Advanced GeoEnvironmental,Inc. <br /> r <br />