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i Method 8260FA for oxygenates including 1,2-DCA and EDB. All water sample analysis and groundwater elevations are summarized in the attached tabular recap sheet (see attached recap sheets).Copies ofthe original Laboratory data sheets from this sampling event are also attached and are a part of this report. Findings The groundwater elevation at time of monitoring was lower than the last monitoring event by as much as 0.8 feet. MW-1 continues to have the highest concentration of gasoline contamination for TPHg at 107,000 ppb.which is lower than 169,000 ppb.ofthe last sampling event.The groundwater hydraulic gradient was calculated at S=0.005 with the down slope in the northwest direction,which is a deviation from the historical data. Typically the hydraulic gradient is down slope to the northeast. The gradient is determined by the first ground water elevation data of MW-1,MW-2,and MW-3 (see a site map attached). Conclusions The hydraulic gradient for this monitoring event is not in the traditional hydraulic gradient flow direction of northeast. This is the second consecutive quarter that the groundwater flow is in the west or northwest direction. In general, all of the monitoring well groundwater samples, with the exception of MW-5,yielded higher concentrations of TPHg than last quarter. The MW-1 groundwater sample results were lower in concentrations than last years fourth quarter monitoring event. MTBE was detected in MW-1, MW-1R,and MW-2. Low concentrations of 1,2-DCA were detected in in MW-1,MW-1R,MW-2, and MW-3. Low concentrations of EDB were analyzed in MW-1, MW-IR, and MW-2. Recommendations The author recommends that monitoring well sampling be continued on a quarterly basis. The EDH has requested that this site be analyzed for both 1,2 DCA and EDB. It is recommended that this analysis for oxygenates in the future only be done on MW-1 and MW-2. Work in ]Progress The extraction well is installed. The work plan calls for mobilization of a 21,000 gallon tank and pump installation for the pump test. This work will be started when the UST Fund is current on reimbursement for this site. At the present time, funds for the completion of this work plan are not available. Spoil removal and site maintenance is planned for the near future. The repair of monitoring wells MW-8D and MW-8S are scheduled for the near future. Please contact Ervin Rifenburg of this office at (209)368-9381 if you have any questions on this report. Respectfully submitted, �w��Jit►AIF1'V. �F . Foo Bering rvm Rif > s� �OFC cc: Michael D. & Sharon Olivarez, 4 cotts Ave. Stockton, Ca. 3