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Working To Restore Nature <br /> . March 18, 1993 <br /> ARCO Station No 6100, Tracy, California <br /> a depth of 62.5 feet to reduce the length of screen in this well to Just the portion of the soil <br /> affected by gasoline hydrocarbons Details re f more detail inon well construction an attachment to #hisrrepoot n <br /> on the Logs of Borings and are discuss <br /> 1 <br /> Cuttings generated during drilling were placed on and covered with plastic and left at the <br /> site. Soil samples were collected from the drill cuttings <br /> llforaltis toaaldisposal <br /> ispo al <br /> options Dillard Trucking of Byron, California, will he cuttings an <br /> appropriate landfill after they complete the profiling of the soil <br /> 1 <br /> Laboratory Analyses and Results <br /> Select soil samples collected from the borings and the sample from the drill cuttings were <br /> submitted to Sequoia Analytical Laboratory in Sacramento, California (Hazardous Waste <br /> Testing Certificate No 1624), for analysis of total petroleum hydrocarbons as gasoline <br /> (TPHg) and benzene, toluene, ethylbenzene, and total xylene isomers (BTEX) using <br /> Environmental Protection Agency (EPA) Methods 5030 and 8020, respectively The sample <br /> from the dill cuttings was also analyzed for organic shown on Tab a 1.e California LUFT <br /> Method Analytical results of the soil sample <br /> 10 .� Analytical results indicated gasoline hydrocarbons atterson Pass detected in <br /> iTPHg was detected at a <br /> from boring B-27 drilled in the shoulder <br /> concentration of 8,800 ppm from 40 feet bgs, and only trace concentrations of benzene, <br /> toluene and total xylene isomers were detected at 115 feet bgs. Residual gasoline <br /> hydrocarbons were not detected 16 5 feet bgs in boring B-28, and only trace concentrations <br />• of benzene, toluene and total xylene isomers were detected at depths of 64 and 71 feet bgs <br /> Gasoline hydrocarbons were detected in the samples collected from boring B-26, TPHg <br /> concentrations ranged from 3,200 ppm to 10,000 ppm in soil from 66 5 to 85 5 feet bgs <br /> Analytical results are shown in Table 1 <br /> CONCLUSIONS <br /> Based on results of this investigation, RESNA concludes that the lateral extent of gasoline <br /> hydrocarbons in soil beneath the site has been delineated, however, the lateral extent of <br /> residual gasoline hydrocarbons has not been delineated offsite, southeast of boring B-26 <br /> Plate 13 shows the extent of residual gasoline hydrocarbons in soil The distribution of the <br /> highest concentrations of residual gasoline hydrocarbons isoil lshown on Platerogr14 essively <br /> b <br /> deeper from the dispenser islands toward g B-26 This <br /> • <br /> 1231ccar 3 <br /> 30041,4 <br /> 0 <br />