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Date: February 19,2003 Quarter: 4`" Quarter,2002 • Elevated reporting limits were the result of dilutions performed by the laboratory. • The 8260 data for sample VW-5D may be biased low due to holding time issues(analyzed 23 days after collection). • In the 8260 analysis of sample VW-3 the surrogate was outside of acceptable recovery limits.The results for all analytes in these samples should be considered estimated. Air samples collected on 10116/02: 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: • In the TPHg analysis of samples INF Total Air and INF CAT Air, the hydrocarbon pattern present is within the gasoline quantitation range but does not resemble the pattern for gasoline. • Due to surrogates falling outside control limits,INF Total Air results may be biased high and INF CAT Air may be biased low. Air samples collected on 11/19102: 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: • In the TPHg analysis of samples TNF Total Air and INF CAT Air the hydrocarbon pattern present is within the gasoline quantitation range but does not resemble the pattern for gasoline. Air samples collected on 12/26102: Based on the review of the analytical and bardcopy 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. DISCUSSION: TPHg,benzene,toluene,ethylbenzene and total xylenes were reported in wells sampled this quarter at concentrations that were generally consistent with previous quarterly monitoring events. Fuel oxygenates including methyl tert- butyl ether (MtBE), tert-butyl alcohol (TBA), and 1,2-dichloroethane (1,2-DCA) were also reported in groundwater samples collected this quarter at concentrations that were consistent with historic data. Groundwater elevations in site wells generally decreased during the quarter. The inferred groundwater flow direction was consistent with previous monitoring events. Three site visits were conducted to optimize and maintain the SVE/AS system. Approximately 48 lbs of TPHg were removed during the fourth quarter 2002, with a cumulative mass of approximately 1,693 lbs since startup(09/28/00). The SVE system was in compliance with the San Joaquin Valley Unified Air Pollution Control District permit to operate. 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. KAJS BY ARCO'0054814 QTR OZ548 G"R4QOUs Page 2