ARCHIVED REPORTS_SEMI ANNUAL GROUNDWATER MONITORING OCTOBER 2010

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Table 5 Historical Groundwater Monitoring Data and Analytical Results Chevron Facility#306620 (Former Unocal #5098) 5606 Pacific Avenue Stockton,California EXPLANATIONS: -- Groundwater Monitoring data and laboratory analytical results prior to January 26,2007,were compiled from reports prepared by ENSR Corporation. TOC=Top of Casing GRO=Gasoline Range Organics (µg/L)=Micrograms per liter (ft.)=Feet TPH-G=Total Petroleum Hydrocarbons as Gasoline ND=Not Detected DTW=Depth to Water B=Benzene --=Not Measured/Not Analyzed GWE=Groundwater Elevation T=Toluene (D)=Duplicate (msl)=Mean sea level E=Ethylbenzene SPH=Separate Phase Hydrocarbons SPHT=Separate Phase Hydrocarbon Thickness X=Xylenes QA=Quality Assurance/Trip Blank TPH=Total Petroleum Hydrocarbons MTBE=Methyl Tertiary Butyl Ether NOTES: Wells MW-1 through MW-7 are owned by Montgomery Ward and are located on 5400 Pacific Avenue. Depth to ground water measurements for these wells were obtained by Environmental Audit,Inc. Wells MW-10 through MW-17 are owned by Unocal and are located on 5606 Pacific Avenue. Depth to ground water measurements for these wells were obtained by MPDS Services,Inc. " The elevations of all wells were surveyed to City of Stockton Benchmark No. 14(elevation--10.95 MSL). Elevations surveyed by Morrow Surveying on December 16,2004. Elevations are surveyed to City of Stockton benchmark No. 14. Elevations surveyed by Morrow Surveying on August 26,2004. Elevations are surveyed to City of Stockton benchmark No. 14. A Well was resurveyed on June 24, 1998. B Elevation surveyed by Morrow Surveying on October 15,2005. Elevations are surveyed to City of Stockton benchmark No. 14. 1 Although sample contains compounds in the retention time range associated with gasoline,the chromatogram was not consistent with the expected chromatographic pattern or fingerprint. However,the reported concentration is based on gasoline. 2 Samples collected on August 31,2004,were subsequent to well development. 3 Sample reported by laboratory as weathered gasoline. 4 MW-28 was resampled on October 27,2005,as a result of gasoline,acetone,and 2-Butanone reported in sample collected on October 11,2005. 5 MW-23S and MW-23D were resampled on November 9,2005,as a result of gasoline(in MW-23S only),acetone,and 2-Butanone reported in samples collected on October 11,2005. Results from the November 9th event were below laboratory reporting limits for all analytes. 6 The surrogate recovery for this sample is outside of established control limits due to a sample matrix effect. ° MW-9R and MW-10 were resampled on February 9,2006,as a result of TPH-G and VOC concentrations reported in samples collected in January of 2006. 8 The method blank contains analyte at a concentration above the MRL;however,concentration is less than 10°/a of the sample result,which is negligible according to method criteria. 9 The reported concentration of TPH-GRO does not include MTBE or other gasoline constituents eluting prior to the C6(n-hexane). TPH-GRO range start time. 10 BTEX and MTBE by EPA Method 8260. 11 Laboratory report indicates estimated value. 12 BTEX by EPA 8260. 13 Data provided by AECOM. 60146576 59 of 59 AECOM