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Mr. Dan Barber Project OF90-002.02 <br /> October 28, 1992 <br /> Page 4 <br /> Stockpiled Soli Sample Analysis <br /> iThe four soil samples, designated Comp 1 through Comp 4, were to be composited <br /> into one sample and analyzed for TPHD; however, one of the four samples was <br /> collected from the soil which was excavated near the surface, and it was believed to <br /> contain some asphaltic material. For this reason, this sample, Comp 4, was analyzed <br /> separately for TPHD. The remaining three soil samples were composited into one <br /> sample (designated composite sample A), which was also analyzed for TPHD. <br /> Analytical Results <br /> Table 1 presents the stockpiled soil sample analytical results, and the certified <br /> analytical reports are presented in Appendix B. Comp A and Comp 4 contained 17 and <br /> 49 mg/kg of petroleum hydrocarbons, respectively. These concentrations were <br /> reported as TPHD; however, the petroleum hydrocarbon in the samples was reported <br /> to be a higher boiling point hydrocarbon than diesel. <br /> CONCLUSIONS AND RECOMMENDATIONS <br />' Based on observations made in the field during the overexcavation activities and on <br /> confirmation and stockpiled soil sample analytical results, it appears that the soil in the <br /> vicinity of the former tank E location is minimally impacted with petroleum <br /> hydrocarbons. The concentrations of TPHD detected in samples north 0.8' and <br /> Comp 4 are attributable to the presence of asphaltic materials in these samples. <br /> EMCON Associates recommends that the San Joaquin County Public Health Services <br /> and the Regional Water Quality Control Board grant closure for this portion of the <br /> Teichert facility at 103 North E Street, Stockton, California, for the following reasons: <br /> G Activities related to the use of tank E appear to have <br /> minimally impacted soil at the site. <br />' G The excavation was backfilled with minimally impacted <br /> native soil. <br /> G The depth to ground water is greater than 50 feet based on <br /> water-level data gathered in August 1992. <br /> G The area over the tank E excavation will be capped with <br /> either asphalt or concrete. <br /> LIMITATIONS <br /> The services described in this report were performed consistent with <br /> generally accepted professional consulting principles and practices. No <br /> other warranty, express, or implied, is made. These services were <br /> performed consistent with our agreement with our client. This report is <br /> pio10f OV9000202aw <br />