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ri Mr Mike Infurna Page 2 On December 18, 2002, wells MW1, MW2, MW3, MW4 and U-Haul well MW7 were purged and sampled At least three well casing volumes were purged from each well During the purging process, temperature, pH and electrical conductivity parameters were measured Groundwater samples were collected after physical parameter stabilization and appropriate groundwater recovery The samples were placed in an ice chest refrigerated to a temperature of approximately 4°C Purgewater was contained in appropriately labeled DOT-approved 55-gallon drums Purge logs are included in Attachment A Groundwater samples were delivered under chain of custody protocol to Argon Laboratories (FLAP #2359) Analysis consisted of gasoline oxygenate additives, 1,2-DCA and EDB using EPA method 8260, BTEX using EPA method 8020, and TPHg using modified EPA method 8015 GROUNDWATER ANALYTICAL RESULTS Gasoline oxygenate additives and EDB were not detected in any well 1,2-DCA was not detected in wells MW1 and NM, although the sample from MW1 had an elevated detection limit Relative to the previous sampling event, the concentration of 1,2-DCA decreased in wells MW1, MW2 and MW4 but increased in well U-Haul MW7 • TPHg and benzene were detected in each well Dissolved TPHg concentrations ranged from 130 parts per billion (ppb) in MW3 to 180,000 ppb in NM Benzene levels ranged from 1 3 to 12,000 ppb in wells NM and MW1, respectively TPHg and BTEX concentrations were within historical ranges in wells MW1, MW2, NM and U-Haul MW7 Levels of these analytes in MW4 were the highest to date Analytical results are summarized in Table 2 Attachment B contains laboratory reports and chain of custody documentation SUMMARY • Groundwater levels rose since September 2002 Groundwater flowed in a southerly direction • Concentrations of TPHg and BTEX reported in wells MW 1, MW2, MW3 and U-Haul MW7 were similar to historical levels Petroleum hydrocarbon levels in well MW4 increased significantly since the previous event Since the previous sampling event concentrations of 1,2-DCA decreased or remained non-detectable an all wells except U-Haul MW7 Well installation permit applications for the proposed additional monitoring wells have been submitted to your office and encroachment permits from San Joaquin County Department of Public Works have been applied for \kGZA_FSISYSO11Data\GROUNDZE\HARRYS\ReportslQMR12002\4QM2002 doc