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Date. July 23,2004 Quarter 2° Quarter,2004 r� 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 laboratory with the following limitations • The reported results for gasoline range organics (GRO) in samples MW-1, MW-2, and MW-3 are due to a discrete peak at C6-C7 (probably MtBE) The reported results for methyl tert-butyl ether (MtBE) in sample MW-3 should be considered estimated The initial result exceeded the calibration range of the instrument and the reanalysis may by biased low since the reanalysis for this analyte was performed 1 day beyond the U S EPA recommended holding time of 14 days Consequently,the result from the reanalysis has been summarized in this report • The reported result for tert-butyl alcohol (TBA) in MW-3 may be biased high due to the continuing calibration verification falling outside acceptance criteria The reanalysis for this analyte was performed beyond the U S EPA recommended holding time The result from the initial analysis has been summarized in this report The elevated reporting limits were the result of dilutions performed by the laboratory in order to quantitate a target analyte DISCUSSION: GRO,total xylenes,MtBE, and TBA were reported above method detection linuts in groundwater samples collected from site monitoring wells this quarter MtBE concentrations increased in monitoring wells MW-1 and MW-2 this quarter but remain within historical ranges MtBE concentrations in MW-3 and MW-4 decreased to the lowest level reported historically Total xylenes were reported above method detection limits in MW-4 for the first time historically Other analyte concentrations were generally consistent with previous sampling events . Groundwater elevations in site monitoring wells increased relative to the previous monitoring event The inferred direction of groundwater flow across the site was ranged from the northeast to the south at an average hydraulic gradient that ranged from 0 002 to 0 005 ft/ft 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 FIGURES Figure l Groundwater Elevation Contours Figure 2 Groundwater Analytical Summary Figure 3 Concentration and Water Level Trends(Well MW-3) APPENDICES Appendix A Sampling and Analysis Procedures Appendix B Laboratory Analytical Report,Chain-of-Custody Documentation, and Field Data Sheets Appendix C GeoTracker Upload Confirmation • K\Wpr ssUS SP ARCO\11191\Qa nerly\2 QTR 04V 1191 CWMR 2Q04 do, Page 2