ARCHIVED REPORTS XR0004091 - Laserfiche WebLink

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the check valve in tube technic. Samples were transported on ice for delivery under chain of custody to Sherwood Labs for analysis. Sample Analysis Water samples were analyzed by EPA methods 602 for BTEX, EPA 5030/8015 for TPHg and EPA 8260b for Oxygenates. Results of all sample analyses are attached in original and recap form. Findings From Water Sample Analysis Contamination of BTEX and TPHg in low concentrations was found in the water of monitoring wells MW#2 and GMX1. The water samples taken from all of the monitoring wells MW#2, MW#4, and GMX-1 contained low levels of MTBE ranging from24 ug/L to 110 ug/L. Tertiary-butanol was detected in GMX1 at 120 ug/L. Conclusions The water sample analysis from monitoring weI l GMX 1 indicates higher concentrations of BTEX,TPHg and MTBE compared to the 7112/99 sampling event. Oxygenates have been reduced to non-detect in monitoring wells MW#2 and MW43.The water surface in all of the monitoring wells has lowered about two feet from the last sampling event. The direction of the hydraulic gradient has changed from the Southeast to directly South. Recommendations The reduction in the levels of oxygenates in two of the four monitoring wells is encouraging and may indicate the removal of the source and the natural degradation and mineralization of the hydrocarbons in the groundwater.Foothill Engineering recommends that the quarterly sampling of all the monitoring wells continue for an additional quarter. Three data points for each monitoring well will give enough data for the design of any future reclamation plan. After all three data points have been collected, a soil and ground water reclamation plan should be designed if required by the PHS/EHD. Please contact Ervin Rifenburg of this office (209/368-9381) if any questions arise concerning this Report. Respectfully submitted, Foot ' enn - Ui O 7 ri Ervin Ri enb , RC qf.. cc: Diana Maragos, Attorne West Liquors cc: Geomatrix, Mike Keim FAX 510/663-4141 2