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Extended Plume Def nition:-7500 W 11 th 5[., Tracy,CR. Page 25 Carmelo Avenue. As is documented in Tables 2 and 4, with the exception of a less than significant concentration of a compound in the diesel range, which does not match the laboratory's diesel standard, in the surficial soil at the location of Monitoring Well MW-15, none of the samples recovered from those three wells contained any detectable concentrations of analytes of concern. Thus, when synthesized with the data from the other wells by then extant at the Navarra Site, and without consideration for slight adjustments to the details of its geometry, the areal extent of fuel hydrocarbons in the subsurface beneath the primary plume was confirmed by the additional site characterization that is documented in this report. 7.1.2 Distribution of Anal es of Concern in the Interior of the Primm Plume In addition to installation of wells to confirm the perimeter of the primary plume, additional wells were installed in April 2004 to further investigate the variation in concentration of analytes of concern in the interior of the plume and their variations with distance down- gradient from the point where fuel hydrocarbons had been discharged at the 7500 West Eleventh Street property. The locations of those wells, designated Monitoring Wells MW-13, MW-14, MW-16 and MW-18, are also shown on Figure 2. It is instructive to review the results of soil samples recovered from the borings drilled for those wells together with the results of the analyses of soil samples recovered from the borings drilled to install Monitoring Wells MW-3, MW-7, MW-11 and MW-19, each of which is arrayed along the median axis of the primary plume. Such review shows that, with trivial exception, soil in the ' subsurface further down-gradient from Monitoring Well MW-7 (i.e., to the north of West Eleventh Street)is free of detectable concentrations of analytes of concern. The distribution of concentrations of analytes of concern in samples of groundwater recovered in April 2004 is also consistent with the plume characteristics previously interpreted by SJC. From Monitoring Well MW-7 northward, the concentrations of the analytes are greatly reduced compared to those up-gradient from that monitoring well, with only 34 µ/L of MTBE and no TPHd, TPHg or BTEX compounds being present in the sample recovered from Monitoring Well MW-11 on April 21, 2004. The concentrations of TPHd and TPHg in the sample recovered from Monitoring Well W-7 on April 22, 2004 were 9,800 and 10,000 pIL, respectively, with commensurately high concentrations of the BTEX compounds. As has been the case in previous monitoring rounds, the absence of detectable concentrations of fuel oxygenates in that sample is attributed to the high concentrations of the TPH and BTEX compounds masking the presence of relatively low concentrations of fuel oxygenates,which were, in fact, likely to have been present in that sample. On April 30, 2004, the concentrations of both TPHd and TPHg, at 470 and 5 200 p g� Nom, respectively, detected in the groundwater sample recovered from Monitoring Well MW-13, which is up-gradient from MW-7 and along the median axis of the plume, were significantly lower than the concentrations of those analytes found in the sample recovered from MW-7. TPHd and TPHg were at the even lower concentrations of non-detectable and 990 µIL, respectively, in the sample recovered from Monitoring Well MW-3 on April 21, 2004. Those t, analytical results confirm SJC's previous findings regarding the beneficial effects on groundwater quality achieved when some 2,000 gallons of LNAPL and groundwater affected - sic