ARCHIVED REPORTS_PHASE II ENVIRONMENTAL SITE ASSESSMENT

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W GIK . Southwest, 1[inc. The MCL, DHS and ESL values are included as general guidelines to assist in data interpretation, as all environmental sites are evaluated by the governing regulatory agency on a site-specific basis, and the listed values are not necessarily action levels for this site. The shallow groundwater that was sampled is not used as drinking water, and the grab samples are intended to give only a preliminary indication of site groundwater conditions. To obtain definitive groundwater data for the site, monitoring wells would need to be installed, developed and sampled in accordance with California Department of Water Resources well standards. Detectable concentrations of all CAM17 metals were found in some of the groundwater samples. However, concentrations of metals exceeding the MCLS were detected only in the unfiltered samples from B-1 through B-7, located in the northwest portion of the site. These samples reflect both dissolved metals and particulate metals in the groundwater, and thus cannot be held to MCL standards. None of the filtered groundwater samples from B-8 through B-18 exceeded MCLS for metals. PCB concentrations exceeding the MCL of 0.5 µg/L were found in groundwater grab samples • from borings B-3, B-4, B-6, B-7, B-13 and B-16, with the highest concentration of 15 pg/L detected in B-5. The PCBs consisted of Aroclor 1232, 1242, 1248 and 1254. The PCB concentrations detected in the groundwater samples are shown on Figure 3. TPH-g was detected only in the groundwater grab sample from B-2, located in the northernmost portion of the site, at a concentration of 800 µg/L, which exceeds the ESL. The chromatogram showed the heavier range compounds to be significant, suggesting aged gasoline. TPH-d was detected in all of the groundwater grab samples with the exception of B-12. The diesel concentrations ranged from 60 to 1,100 µg/L, with the highest concentration found in B-8. TPH-d groundwater concentrations exceeding the ESL were found in B-1, B-2, B-4 through B-8, B-13 and B-18. The chromatograms show significant oil and diesel compounds with no recognizable pattern. TPH-mo was detected in 11 of the 17 grab groundwater samples with the maximum concentrations found in B-7 at 3,200 µg/L and B-1 at 2,200 µg/L. The concentrations of TPH-mo in B-1, B-2, B-4 through B-8, B-13 and B-16 through B-18 exceeded the ESL. The TPH-d and TPH-mo concentrations detected in the groundwater samples are shown on Figure 4. • 704. PRI.05 23 July 21, 2008