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13E011 ATRIX 16 performing two groundwater monitoring events in the four groundwater monitoring wells. Analytical results for soil samples collected from the confirmation soil boring drilled adjacent to boring SBI indicated that TPH-G was present in soil at concentrations greater than 100 mg/kg and the Step 2 approach was implemented. 4.0 FIELD ACTIVITIES Soil boring SB6 was drilled adjacent to boring SB I (Figure 2)to confirm the presence of TPH-G in soil previously reported at a concentration of 300 mg/kg at a depth of 15 feet. Soil samples collected from ' boring SB6 indicated that TPH-G was present in soil at a concentration greater than 100 mg/kg, and additional soil assessment was performed. The additional soil assessment consisted of advancing eight soil borings (SB7 through SB14) at the locations shown on Figure 2 to define the lateral and vertical ' extent of soil impacted with TPH-G at concentrations greater than 100 mg/kg. One additional ground- water monitoring well was installed downgradient and outside of the area of affected soil as defined by ' the additional soil assessment at the location shown on Figure 2. Groundwater monitoring was per- formed twice in the three previously installed wells and the newly installed groundwater monitoring well. Field activities were coordinated by a Geomatrix staff geologist under the direction of a Geomatrix principal geologist registered in the State of California. Field activities were performed in accordance with a health and safety plan prepared for this site. Permits for the soil borings and installation of the monitoring wells was obtained from the SJCEHD. Underground Service Alert was contacted to provide ' utility clearance. Boring logs prepared for all borings advanced during this assessment are presented in Appendix A. 4.1 Drilling and Sampling of Confirmation Boring SB6 ' The confirmation soil boring was drilled on 20 October 1995. Drilling services were provided by Spectrum Exploration, Inc. of Stockton, California. Boring SB6 was advanced to a depth of 55 feet bgs (the top of the groundwater surface) using a drill rig equipped with hollow-stem augers. All sampling ' equipment was cleaned prior to use and between each sampling event. Soil samples were collected with a split-barrel sampler every 5 feet for lithologic logging, field screening, and possible submittal for chemical analysis. Lithologic logging was performed using visual/manual procedures according to the Unified Soil Classification System described in American Society for Testing and Materials Standard D 2488-90. Field screening procedures included examining the soil sample for visual evidence (dis- coloration)-and-olfactory-evidence-(odor)-of-gasoline as-well as measuring-volatile organic=compounds— -- -- -- in the headspace above the sample using an organic vapor meter (OVM). Soil samples retained for chemical analysis were removed from the sampler, sealed with Teflon sheeting, plastic lids, and tape, labeled, and placed in an ice-cooled chest for subsequent delivery under chain-of-custody procedures to the laboratory. 3