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VOCs using EPA Method 524.2; SVOCs and Phenols using EPA Method 525.2 Metals (Arsenic, Cadmium, Chromium, Lead, Zinc) using EPA Method 6010B. Validated, groundwater analytical results are summarized in Table 1 (attached). The analytical results were compared to EPA Region 9 Preliminary Remediation Goals (PRGs) and Federal and State Maximum Contaminant Levels (MCLS). All analytical results for the third sampling event were below the PRGs and MCLS. The detected contaminants of concern show the following trends: Chromium was present in both residential wells at roughly constant levels, ranging from 5.2 gg/L to 6.0 gg/L at 30010 South MacArthur Road, and 10.7 gg/L to 11.5 gg/L at 8930 Palmquist. The well at Teichert Aggregates had detectable concentrations of chromium in the first two sampling events (5.7 gg/L and 5.5 gg/L) that decreased to below the detection limit of 5.0 gg/L in the third sampling event. Zinc concentrations at 8930 Palmquist decreased from 507 to 344 gg/L between the second and third sampling events. Zinc was detected in one sample at 30010 MacArthur at 72.5 gg/L in the third sampling event only, but was below the detection limit of 50 gg/L in the duplicate sample taken at that location. The discrepancy is likely due to a high level of uncertainty near the detection limit. Lead was detected in two separate samples, one from RMC Lonestar in the first sampling event at 7.6 gg/L, and one in the third sampling event at Teichert Aggregates at 3.9 gg/L. These do not appear to be part of a continuing pattern. CONCLUSIONS Based on a review of the available information, groundwater sampling analytical results do not indicate that there has been any impact to water quality of these wells due to the Tracy tire fire. If you have any question, please contact me at (415) 981-2811, ext. 233. Respectfully submitted, Cheryl LeCompte START Member cc: Donn Zuroski, OSC, Emergency Response Office, EPA, Region 9 file