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S <br /> REMEDIATION CONRRMATION SAMPUNG RESULTS <br /> AND CLOSURE RECOMMENDATION REPORT <br /> (March 1994 Revislon) <br /> 909 West Hammer Lane Stockton California <br /> On ,dune 3, 1993, Aegis drilled three soil borings, SB-8, SB-9, and SB-10 (Figure 2) to <br /> confirm soil remediation The locations of the soil borings were based on a) previous soil <br /> sampling locations, b) EA's workplan, and c) input by the PHS/EHD These locations <br /> represent what was considered by the PHS/EHD as the area most impacted by the <br /> leaking UST system <br /> I <br /> I <br /> 4 1 Soil Borings <br /> The three soil borings were drilled using 8-inch diameter, hollow-stem augers following <br /> Aegis' Standard Operating Procedures (SOP) included as Appendix A The borings were <br /> drilled to the first occurrence of groundwater, typically 58 feet Soil samples were <br /> collected at 5-foot intervals in each boring To fully characterize the soil, all samples (36) <br /> collected were submitted for laboratory analysis Boring logs are included in Appendix B <br /> 4 2 Soil Sample Analytical Resufts <br /> The soil samples collected were submitted under chain-of-custody to Pace Incorporated, <br /> of Novato, California, a state-certified analytical laboratory The samples were analyzed <br /> for <br /> a) TPH, as gasoline (TPH-G), by GC-FID/EPA Methods 503018015, and, <br /> b) benzene, toluene, ethylbenzene, and total xylenes (BTEX) by EPA Method 8020 <br /> Laboratory analytical reports indicated petroleum hydrocarbons in two of the borings, <br /> SB-8 and SB-9 One sample from SB-8, SB 8-6 at 6 feet, contained detectable <br /> concentrations of toluene, ethylbenzene, and xylenes of 0 062, 0 0098, and 0 045 ppm, <br /> respectively Of the 12 samples collected from SB-9, nine samples contained detectable <br /> concentrations of petroleum hydrocarbons (Table 1) The highest concentrations were <br /> found at 21 feet in SB 9-21 No benzene was detected at or above the laboratory <br /> detection limits in any of the samples submitted for analysis Petroleum hydrocarbon <br /> constituent concentrations were less than 0 5 ppm deeper than 36 feet Figure 4 is a <br /> distribution map of TPH-G in soil <br /> Laboratory quality assurance and control is addressed in the Aegis SOP included in <br /> Appendix A The analytical laboratory reports and chain-of-custody forms are included <br /> in Appendix C <br /> 93 005C QMR 4 <br />