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limits, and quality assurance and quality control are contained in the TRC report
<br /> (Appendix A).
<br /> 14_ Results_
<br /> . Table 1 presents the results of the soil gas survey. The soil gas results are presented in
<br /> micrograms per liter (ugh) and in parts per million (ppm) to allow for comparison with soil
<br /> sample results. The results of the soil gas analyses indicate that petroleum hydrocarbons
<br /> were detected in the vicinity of the suspected leak near 125 Sixth Street (Plate 2) with
<br /> hydrocarbon levels decreasing in both directions away from the suspected leak location.
<br /> The soil gas analyses primarily detected TVH, C4-C9. The results are summarized as
<br /> follows:
<br /> i..
<br /> • TVH, C4-C9 were detected in concentrations from 2,400 to 7,400 ug/l (620 to
<br /> + 1,900 ppm) at locations E, F, 3, G, H, and I, which are centered around the
<br /> L suspected leak;
<br /> ` • TVH, C4-C9 were detected in concentrations ranging from 50 to 130 ug/1 (10
<br /> L to 34 ppm) at locations 1, A, B, C, 2, D, J, 4, and K which are centered
<br /> around those locations listed above;
<br /> i.. • Of the remaining locations, TVH, C4-C9 were detected in minor
<br /> concentrations ranging from 0.4 to 7 ug/1 (0.1 to 2 ppm) at locations 0, 5, 10,
<br /> ' and 16 while TVH, C4-C9 was not detected at locations 6, 7, 8, 9, 11, 12,
<br /> 13, 14, 15, and 17;
<br /> F • Minor quantities of TVH, C10-CX were detected from 0.7 to 2 ug/1 (0.2 to
<br /> 0.5 ppm) at locations 0, A, and 4;
<br /> • No benzene or ethyl benzene were detected in any of the soil gas samples; and
<br /> • Low levels of toluene, 0.3 to 7 ugh (0.08 to 2 ppm), were detected at
<br /> locations 1, 4, 10, and 16 while total xylenes were detected at 4 ug/1 and 7
<br /> ug/l (1 to 2 ppm) at locations 2 and 4, respectively.
<br /> L 4.0 SOIL SAMPLING
<br /> A total of ten locations were selected to collect soil samples based on the results of the soil
<br /> gas survey. Soil samples were collected at locations 2, E, F, G, and J to confirm the
<br /> presence of petroleum hydrocarbons in the vicinity of the suspected leak near 125 Sixth
<br /> Street. Soil samples were also collected at locations 7, 10, 13, 16, and 17 to confirm the
<br /> low to non-detect hydrocarbon levels of the soil gas samples at these locations. The soil
<br /> samples were collected as close as possible to the depth at which the soil gas samples were
<br /> L obtained.
<br /> �, F:ka1STOCKTON.SO 3
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