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7U30Ud-»4 UUI'1-�� <br /> 4.3.3.2 As discussed in Section 4.3.1, the nine cross-gradient and <br /> upgradient wells were below MCLS for all inorganic parameters tested with <br /> the exception of chromium in Well 5. None of the results from any of the <br /> six downgradient wells exceeded any MCLS for the inorganic parameters which <br /> were tested. <br /> 4.3.3.3 With regard to the organic parameters, two downgradient private <br /> wells contained purgeable halocarbons. The first is Well 12 (Raspo 3AG) . <br /> This well is used for agricultural purposes and is located within 200 feet <br /> of the Depot boundary and downgradient of Contaminant Area 3. The <br /> chemicals detected in Well 12 were TCE at 12 ug/l and PCE at 4.3 ug/1 . As <br /> discussed later in this report, these purgeable halocarbons were the most <br /> frequently detected contaminants in groundwater from monitoring wells <br /> located on the Depot and in Contaminant Area 3. Because of the location of <br /> Well 12 and the chemical constituents found, the TCE concentrations are <br /> believed to be indicative of facility-related contamination. The TCE <br /> concentration in groundwater from Well 12 (Raspo 3AG) exceeded the <br /> California DHS MCL of 5 ug/l for TCE. <br /> 4.3.3.4 A second location with a purgeable halocarbon above the detection <br /> limit is Well 6 (Rose domestic well) , with carbon tetrachloride at <br /> 0.6 ug/1 . Because of the uncertainty associated with results near the <br /> detection limit (which is 0.5 ug/l for carbon tetrachloride) , the absence <br /> of TCE and PCE in the groundwater sample from Well 6, and the absence of <br /> carbon tetrachloride detection in any of the 55 monitoring wells on the <br /> Depot, it is unlikely that this result represents facility-related <br /> contamination and may be a sampling artifact, laboratory artifact, or off- <br /> Depot source. To confirm the presence of this constituent, it may be <br /> desirable to resample this well for purgeable halocarbons. <br /> 4.3.3.5 In summary, based upon the existing information, it does not <br /> appear that groundwater in private wells other than the Raspo Well 3AG has <br /> been impacted by contamination from the Depot. <br /> 4-166 <br />