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_ .. ...... <br /> Extended Site Characterization Report: 7500 West Eleventh Street, Tracy, CA. Page 34 <br /> excavated to expose the surrounding soil to permit observation and sampling of the soil <br /> IN, along their length. Those trenches were designated Pipe Trench No. 1 and Pipe Trench <br /> No. 2; their locations are shown on Figure 3. <br /> The results of analyses of soil samples recovered at intervals along the lengths of the two <br /> pipe trenches are presented in Table 3; the sampling locations are shown on Figures 5 and <br /> ' 7, respectively. <br /> 7.3.1.4.1 Pipe Trench No. I <br /> 1 <br /> Pipe Trench No. 1 connected the former dispenser area with Tank Pit No. 1, which had <br /> contained the four registered tanks in use at the time the Olympian Service Station ceased <br /> operation. Two samples were taken from the bottom of that trench. The samples <br /> contained 930 to 1,200 mg/Kg of diesel and 130 to 530 mg/Kg of gasoline. Each of the <br /> two samples contained very low concentrations of one or more of the BTEX compounds, <br /> . but no MTBE was detected in either sample. <br /> The routing of Pipe Trench No. 1 and the components of fuel hydrocarbons found to be <br /> affecting soil along its length are consistent with an arrangement whereby gasoline and <br /> diesel were pumped from the modern underground tanks that were located in Tank Pit <br /> No. 1 to the dispensing pumps located on the pump islands. Unfortunately, it is apparent <br /> that, although the underground tanks removed from Tank Pit No. 1 did not leak, there <br /> was significant leakage in the underground piping where it was routed to the individual <br /> f ieI dispensers. <br /> 7.3.1.4.2 Pipe Trench No. 2 <br /> A second distinctive pipeline route was found along a line beginning near the <br /> southwestern corner of the former truck service bay located at the rear of the Casa <br /> Mendoza restaurant and terminating at a point in the yard to the west of the restaurant <br /> building. As was the case for the pipe described in Section 7.3.1.4.1, a trench'(Pipe <br /> Trench No. 2) was opened along the length of that pipe and soil samples were recovered <br /> .: from it. Those sampling locations are shown on Figure 7 and the results of the analyses of <br /> ' the soil samples are presented in Table 3. <br /> No detectable concentrations of gasoline or MTBE were found in any of the samples <br /> ' J from Pipe Trench No. 2, althougli some of the samples contained very low concentrations <br /> of one or more of the BTEX compounds. Two of the five contained very low <br /> concentrations of diesel, ranging from 1.0 to 3.1 mg/Kg. <br /> At the time it was removed, the purpose of the pipeline in Pipe Trench No. 2 was not <br /> apparent. However, as can be seen in Figure 3, its alignment suggests that, at some time <br /> in the past, it may have continued in the direction of Tank Pit No. 1 or, possibly, Tank Pit <br /> _ No. 2. At the time it was removed, Dietz Irrigation's Field Superintendent also reported <br /> i that the ground around its southwestern end, near the former truck service bay, appeared <br /> to be disturbed, suggesting that a tank or some other structure, might have, at some time, <br /> sic <br />