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MONITORING WELL SAMPLE EVENT OF 06/11/02 FINDINGS AND RECOMMENDATIONS . Sampling Procedure On June 11, 2002, Del-Tech Geotechnical Services, under the supervision of Foothill Engineering Performed a quarterly sample event. Marcel Delacruz of the Caltrans was notified of the sample event on June 9,2002 as required by Caltrans Permit No,1002-6NV-0218. 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 Waters 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 that sample analysis is part of this report. Sample Analysis Water samples were analyzed by EPA methods 802113 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 plume concentration has changed from the last sampling event.MTBE concentrations in monitoring well GMX-1 have dropped from 38 ug/L on the last event to non-detect on this event. The only monitoring well above the non-detect level for MTBE is MW-3 with 2.9 ug/L. The major changes in TPHg has occurred in extraction well EW-1 with TPHg raising from 2.1 mg/L to 14 mg/L The groundwater surface has raised about +/- 2' from the last event (see Del-Tech Field Report, ienclosed). The groundwater hydraulic gradient is to the south at a slope of S=0.002. Conclusions MTBE above detectable levels only occurred in monitoring well MW-3. During last sampling event MTBE was detected in only monitoring wells GMX-1 and MW-3. Groundwater elevations have risen from the last event about two feet,which is very similar to the same quarter last year. The water sample analysis for monitoring well GMX-1, MW-2 and the extraction well EW-1 continue to produce low levels of TPHg(see Water Sample Analysis Recap attached). Recommendations Quarterly groundwater monitoring should continue as in the past.A Final Remedial Plan has been mailed to your office that recommends a"Pump and Treat"reclamation plan for the contaminated groundwater. Please review that Final Remedial Plan at the earliest date so that this work can proceed. Please contact Ervin Rifenburg of this office (209/368-93 81) if any questions arise concerning this Report. OQROFESS/pN9 Respectfully sub i a RIF�Nd �0 - . Foothi gi enn Gym y - Exp, � is Ervin Rife urg, P OFC cc: Diana Maragos,Attorney for est Liquors, W. T. Mitchell Group 2