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Site Characterization Report: 7300 West Eleventh Street, Tracy, CA. Page 31 -f r- commingle with the primary plume of gasoline and diesel that was generated by leakage from the fuel pipelines beneath the dispensing pumps of the former fueling station. 5.5.3 Summary SJC's interpretation of the areal extent of the primary and secondary plumes of diesel and gasoline are shown in plan view as shaded areas on Figure 13. That drawing also shows, by cross-hatching, the areas where shallow soils are affected by a variety of dispersed hydrocarbons at low or very low concentrations. This dispersion can be attributed to minor leaks and spills onto the surface of the property over its past 70 or more years of life as a truck fueling and service station. The cross-hatched area includes ground along the north side of West Eleventh Street and the area interpreted by GTI to have been affected by hydrocarbons due to leakage from an underground storage tank formerly ! located on the C&B Equipment property at 7474 West Eleventh Street. f The location of the eastern limit of the primary plume of gasoline and diesel and the present position of the down-gradient plume front are somewhat speculative due to the ` limitations imposed on the site characterization program. However, the general distribution of fuel hydrocarbons in the subsurface that is represented by the plan view on Figure 13 and the sectional views on Figures 14, 15 and 16 is well-supported by, and, in each case, is consistent with the hydrostratigraphic, hydrogeoiogical, and geo-chemical data developed by site characterization program. It also comports well with the typical characteristics of fuel hydrocarbon plumes at similar sites that have been explored by SJC and those that have been described in the technical literature.. (Freeze, R.A. and J.A. Cherry 1979.) sic i