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Site Characterization Report: 7500 West Eleventh Street, Tracy, CA. Page 24 5.4 Pipe Trenches Because of the maze of pipelines found in the area beneath the former pump islands, the normal procedure by which a soil sample is recovered at intervals along the length of the j trench from which the pipe has been removed could not be applied at this site. The complex array of piping found beneath the area of the former pump islands was removed in bulk and the area was over-excavated to remove soil affected by fuel hydrocarbons. However, there were two pipelines, the routes of which could be distinctly 1 identified, and it was clear that, when installed, they had been used to connect one area of the site with another. Those pipelines were removed and trenches excavated to expose the surrounding soil to permit observation and sampling of the soil along their length. Those trenches were designated Pipe Trench No. 1 and Pipe Trench No. 2; their locations are shown on Figure 3. The results of analyses of soil samples recovered at intervals along the lengths of the two pipe trenches are presented in Table 1; the sampling locations are shown on Figures 5 and 7, respectively. 5.4.1 Pipe Trench No. 1 Pipe Trench No. 1 connected the former dispenser area with Tank Pit No. 1, which had contained the four registered tanks in use at the time the Olympian Service Station ceased operation. Two samples were taken from the bottom of that trench. The samples contained 930 to 1,200 mg/Kg of diesel and 130 to 530 mg/Kg of gasoline. Each of the two samples contained very low concentrations of one or more of the BTEX compounds, but no MTBE was detected in either sample. The routing of Pipe Trench No. 1 and the components of fuel hydrocarbons found to be affecting soil along its length are consistent with an arrangement whereby gasoline and diesel were pumped from the modern underground tanks that were located in Tank Pit -. No. 1 to the dispensing pumps located on the pump islands that have since been removed. Unfortunately, it is apparent that, although the underground tanks removed from Tank Pit No. 1 did not leak, there was significant leakage in the underground piping where it was -:' routed to the individual fuel dispensers. 5.4.2 Pipe Trench No. 2 A_ secsod_.distinctive pipeline route was found along a line beginning near the southwestern corner of the former truck service bay located at the rear of the Casa Mendoza restaurant and terminating at a point in the yard to the we f the restaurant ; t building. As was the case for the pipe described in Section 5.4.1, a trench (Pipe Trench— >> j; No. 2) was opened along the length of that pipe and soil samples were recovered from it. Those sampling locations are shown on Figure 7, and the results of the analyses of the { soil samples are presented in Table 1. sic