ARCHIVED REPORTS XR0004086 - Laserfiche WebLink

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standards of the industry(see Groundwater Field Report by Del-Tech Geotechnical Services,attached). Purge rates were 0.1 gal/min. Groundwater samples were extracted from each monitoring well using the Watera Inertia Pump technique. Samples were transported on ice for delivery under chain of custody to GeoAanalytical Laboratories for analysis. 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 detectable amounts ofthe Oxygenate MTBE. Samples from monitoring well MW-2 had levels ofBTEX similar to past history. GMX-1 produced samples with highest levels of BTEX for the history ofthe site.Monitoring well MW-3 and MW-4 were non- detect for TPHg, as were the results of the last event. The groundwater surface has raised about+/-T from the last event(see Del-Tech Field Report,enclosed). The groundwater hydraulic gradient is to the south at a slope of S=0.001. The hydraulic gradient slope dropped from S=0.003 on 9/18/01 to S=0.001 for this event. Conclusions MTBE levels remain at near that ofthe last sampling event and occur in only monitoring wells GMX-I 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.Monitoring well MW-2 has levels of Ethyl benzene and Toluene slightly above EPA limits for drinking water. Recommendations Quarterly groundwater monitoring should continue as in the past. The well for the pump test has been installed,and the pump test should be run as soon as possible.Recommendations for groundwater treatment will be made after the results of the pump test are known. Please contact Ervin Rifenburg of this office(209/368-9381)ifany questions arise concerning this Report. Respectfully submitted, It 15$,b Tootl#U30gi %AFEq Ey 147 i b r �. cc: Diana Mara r Sun West Liquors cc: W. T. Mitchell 2