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i Date: May 17,2004 Quarter: 151 Quarter,2004 . Based on the review of the analytical and hardcopy data(chain-of-custody records, blanks, dilutions, holding times, LCSILCSD results,MS/MSD results,and surrogate recoveries),the data are acceptable as reported by the Iaboratory with the following limitations: • The reported result for GRO in sample MW-1 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(s). DISCUSSION: GRO, benzene, toluene, ethylbenzene, total xylenes (BTEX), 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: MtBE concentrations continue to exhibit a decreasing trend in MW-1. In VW-1, GRO and benzene were reported as below method detection limits this quarter and MtBE was reported at the lowest concentration since June 2002. VW-I was sampled on May 3, 2004, not during the scheduled quarterly sampling event on March 11, 2004,due to sampler error. In VW-2,GRO concentrations decreased and TBA was reported at 240 micrograms per liter (pg/L), the highest concentration relative to historic data. This is the first time since December 2002 that TBA was reported above method detection limits in VW-2. Benzene and ethylbenzene concentrations increased in VW-3 but remain within historic ranges. In VW-4,MtBE was reported as below method detection limits for the first time historically and 1,2-DCA was reported as below method detection limits for the first time since June 2003. Due to a discrepancy in the analytical results from groundwater samples collected from vapor extraction wells VW-5S and VW-5D on March 11, 2004, the wells were resampled on May 5,2004. The analytical results from the May 5, 2004, sampling event were consistent with historical data and have been accepted. Consequently, the analytical results from the March 11, 2004 sampling event are considered anomalous and have been rejected. Groundwater elevations generally increased relative to the previous quarter. The groundwater flow direction across the site was toward the southeast with an average hydraulic gradient of 0.006 ft/ft. Three site visits were conducted to optimize and maintain the SVEIAS system. The system run time er uck in November,causing little or no change in run time in the first quarter of 2004. However,the system did o shu down during the quarter, and the system operated without shutdown. Approximately 14.5 lbs of TPHg ere moved during the first quarter 2004,with a cumulative mass of 2,005 lbs being removed since startup(09/2$1 The SVE system operated 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 remedial system performance data is located in Appendix A (Remedial System Performance Evaluation). 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 I Groundwater EIevation 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 1 Groundwater Elevation Contours Figure 2 Groundwater Analytical Summary K\wp�sM BP ARC0\n0548\Q-anfrryu QTR 04\548 GWMR i QW.aoc Page 2