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MONITORING WELL SAMPLE EVENT OF 02/26/02 FINDINGS AND RECOMMENDATIONS Sampling Procedure On February 26, 2002 Del-Tech Geotechnical Services, under the supervision of Foothill Engineering performed a quarterly sample event.Monitoring wells were vented and purged by standard of the industry methods(see Groundwater Field Report by Del-Tech Geotechnical Services,attached).Purge rates were 0.5 gal/min. Groundwater samples were extracted from each monitoring well using the Watera Inertia Pump technique with dedicated sample tubes. Samples were transported on ice for delivery under chain of custody to GeoAanalytical Laboratories for analysis. The new extraction well was also sampled and the sample analysis is part of this report. Sample Analysis Water samples were analyzed by EPA methods 8021 B for BTEX, 5030/Luft for TPHg, and EPA 8260B for Oxygenates.Results of all sample analyses are attached in the original laboratory form and in recap form. Findings From Water Sample Analysis The samples from monitoring well MW-3 and GMX-1 both produced low detectable amounts of the Oxygenate MTBE. None of the monitoring wells produced a sample with detectable amounts of tert- .Butanol.Samples from monitoring well MW-2 had highest levels of benzene which is similar to past history. GMX-1 produced samples with the highest level of MTBE at 38 ug/L for all the monitoring wells. Monitoring wells MW-3 and MW-4 were non-detect for TPHg, as were the results of the last event. Monitoring well MW-3 continues to have very small amounts of MTBE at 1.6 ug/L. The newly installed extraction well, EW-1, contained low levels of TPHg at 2.1 mg/L. . The groundwater surface has raised about-f-/-2.2'from the last event(see Del-Tech Field Report,enclosed). The groundwater hydraulic gradient is to the southeast at a slope of S=0.001. Conclusions MTBE levels remain at the same levels as the last sampling event and occur in only monitoring wells GMX- 1 and MW-3. Monitoring well GMX-1 is the only monitoring well that exceeds proposed allowable concentrations for MTBE of 14 ppb. Groundwater elevations have risen from the last event about two feet and are about 1.5' lower than the same quarter last year. The water sample analysis for monitoring well GMX-1 and MW-2 continue to produce low levels of TPHg. Recommendations Quarterly groundwater monitoring should continue as in the past.The extraction well for the pump test has been installed,and the pump test has been completed.Recommendations for groundwater treatment will be trade after the pump test report has been completed by ACT Inc. Please contact Ervin Rifenburg ofthis office(209/368-9381)if any questions arise concerning this Report. Respectfully submitted, QRQfsS/py� �w¢py�N RIFEAf Foot • gi ering c 1g7 rn Ervin Rifen GN1L OFC cc: Diana Maragos, Attorney for Sun West Liquors, W. T. Mitchell Group 2