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Date: July 28,2004 Quarter: 2nd Quarter,2004 . Based on the review of the analytical and hardcopy data (chain-of-custody records, blanks, dilutions, holding times, LCS/LCSD results,MS/MSD results,and surrogate recoveries), the data are acceptable as reported by the laboratory with the following limitations: + The reported result for gasoline range organics (GRO) in sample MWA is due to a discrete peak at C-5 (probably MtBE). • The elevated reporting limits were the result of dilutions performed by the laboratory in order to quantitate a target analyte. DISCUSSION; GRO, benzene, ethylbenzene, total xylenes, methyl tert-butyl ether (MtBE), tert-butyl alcohol (TBA), and 1,2- dichloroethane (1,2-DCA) were reported above method detection limits in groundwater samples collected from site wells this quarter. Analyte concentrations were generally consistent with historical data with the following exceptions: GRO, benzene, total xylenes, and MtBE concentrations in VW-1 increased but remain within historic high ranges and TBA was reported at the highest concentration historically. In VW-2,GRO and TBA were reported as below method detection limits and 1,2-DCA decreased this quarter. GRO, benzene, ethylbenzene, MtBE, TBA, and 1,2-DCA concentrations in VW-3 were consistent with concentrations reported during second quarter 2003 which is a decrease in concentration relative to the three previous quarters. Ethylbenzene and total xylenes concentrations decreased in VW-5D to the lowest concentration reported since June 2003. Groundwater elevations generally decreased relative to the previous quarter. The groundwater flow direction across the site was toward the east-northeast with an average hydraulic gradient of 0.004 ft/ft- The SVE treatment system consists of a catalytic oxidizer which treats the extracted vapor stream and discharges into • the atmosphere in compliance with the San Joaquin Valley Unified Air Pollution Control District permit to operate N-4124-1-0, which expires in September 2005. The system bad an operation uptime of 96% during the quarter. No GRO, benzene, or MtBE were present in the influent soil vapor samples during the quarter, and the system was permanently shut down on June 9,2004. The remedial system performance data is located in Appendix A(Remedial System Performance Evaluation). The system was turned of on June 9,2004, due to low influent concentrations and reduced groundwater concentrations. This report is based on data, site conditions, and other information that are generally applicable as of the date of the report, and the conclusions and recommendations herein are therefore applicable only to that time frame. TABLES Table 1 Groundwater Elevation and Analytical Data Table 2 Fuel Oxygenates Analytical Data Table 3 Groundwater Gradient Data Table 4 Analytical Results of Soil Vapor Treatment Analysis FIGURES Figure i Groundwater Elevation Contours Figure 2 Groundwater Analytical Summary • K:SWprocess1l5 BP ARCOW5485QaaVertyl2 QTR 045548 GWMR 2Q04.doc Page 2