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Chevron Environmental Management Company Soil and Groundwater Investigation Report Tracy Byron Road Project 5.2.3 Investigation Derived Waste Soil cuttings were stored in two properly labeled 55-gallon DOT-rated drums and stored at Caldron's General Store(2650 West Byron Road)under access agreement,pending disposal by ChevronTexaco. SAIC collected a composite soil sample from the two drums and submitted the sample to Lancaster for analyses. 6. DISCUSSION Residual petroleum hydrocarbons quantified as crude oil were not detected in soil samples collected from six of the 36 borings advanced during this investigation(SB-1, SB-4, SB-7, SB-20, SB-29, and SB-31). In general, laboratory results of soil samples analyzed during this investigation contained either concentrations of TPHc near or below the laboratory reporting limit(<4.0 mg/kg or 8.0 mg/kg), or concentrations well in excess of 100 mg/kg. Concentrations of TPHc above 10 mg/kg were not reported in 33 of the 35 samples submitted from the bottom of the borings. A soil sample from SB-22 at total depth(41 feet bgs) was submitted but not analyzed due to concerns of sample cross-contamination from SPO encountered in the borehole. Samples collected from the two remaining borings contained low-level concentrations of TPHc at 39 mg/kg(SB-8-28) and 30 mg/kg(SB-13-24). Based on the analytical results and the 100 mg/kg action-level threshold,the lateral extent of petroleum-affected soil in 15 of the 36 borings appear to be delineated for the purpose of this investigation(SB-1, SB-4, SB-5, SB-7, SB-13 through SB-17, SB-20, SB-21, SB-27, SB-29, SB-31, and SB-32). Based on the analytical results and the 100 mg/kg action-level threshold,the vertical extent of petroleum-affected soil in 33 of the 35 soil borings appears to be delineated. For a more detailed discussion, SAIC divided the TBRP into four sections. This division was performed in order to group the results and classify the areas as petroleum affected or non-affected. A comparison of data collected during the installation of the WSCO and the TB" soil and groundwater investigation reveals consistencies with respect to the area of affected soil encountered along the West Byron Road corridor. These similarities appear in the lateral and vertical extent of petroleum-affected soil(Figures 3a through 3d). A Site Map and Cross Section Insert are located in Appendix F. 6.1 SECTION SB-1 THROUGH SB-7—AREA WEST OF INTERSTATE 205 Borings SB-1 through SB-7 were drilled west of Interstate 205. There are no properties with residences adjacent to the southern easement adjacent to West Byron Road between Von Sosten Road and Interstate 205. The area where borings SB-1 through SB-7 were drilled could not be correlated with boring logs of dewatering wells or trench logs of the WSCO excavation due to the extent of the WSCO project. Collected and analyzed soil samples from borings SB-1, SB-4, SB-5, and SB-7 did not contain concentrations of TPHc higher than 10 mg/kg. However, soil samples collected from borings SB-2, SB-3, and SB-6 contained concentrations of TPHc over 100 mg/kg. One grab groundwater sample was collected and analyzed from SB-4 (GW-4-12) located in this section. TPHd were detected in water sample GW-4-12 at a concentration of 67 µg/L, which is below the 100 µg/L (or parts per billion) of the Taste and Odor Thresholds(RWQCB A Compilation of Water Quality Goals,Marshack,2000) for diesel. Soil and groundwater in the vicinity of SB-2, SB-3, and SB-6 is not fully characterized and the lateral extent of residual petroleum is not known. Concentrations of residual petroleum in soil are presented on Figure 3 a. Concentrations of petroleum constituents in groundwater are presented on Figure 4a. 6.2 SECTION SB-8 THROUGH SB-16-AREA BETWEEN LAMMERS ROAD AND FORMER NICHOLAW PROPERTY Borings SB-8 through SB-16 were advanced in the area east of the Interstate 205 overpass beginning at the intersection of South Lammers Road and extending to the point where the former Nicholaw property fronts West Byron Road. At least one boring was installed in front of each rural property identified. Observations made during the installation of dewatering wells and trench excavation of the WSCO 8