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Emit' <br /> Mr James Barton <br /> November 2, 2004 <br /> Page 5 <br />' Well Surveying <br /> Groundwater monitoring well MW-31 and MW-32 will be surveyed by a California licensed land <br /> surveyor in accordance with State of California Assembly Bill AB2886 prior to the first quarter <br /> 2005 monitoring and sampling event The top-of-casing (TQC) elevation of the monitoring well <br /> and ground surface elevation will be surveyed relative to mean sea level within 0 01 foot <br /> Permitting and Scheduling <br />' ENSR will submit soil boring/well installation permit applications to the SJCEHD Following <br /> approval of well installation permits the proposed scope of work will be implemented <br /> Anticipated submittal date for the soil boring permits is November 3, 2004 <br /> 1' Conclusions/Recommendations <br /> Groundwater analytical results from the July 2004 monitoring and sampling event appear to <br /> show recent plume movement as evidenced by concentrations of petroleum hydrocarbons in <br /> wells MW-14 and MW-18D screened in Unit B to the north and east of the former Unocal site <br /> Groundwater samples collected from wells MW-14 and MW-18D contained concentrations of <br /> petroleum hydrocarbons, including TPHg and benzene above laboratory reporting limits <br /> Concentrations of TPHg and benzene in groundwater were reported at 80 Ng/L and 6 0 pg/L, <br /> respectively in samples collected from MW-14 Concentrations of TPHg and benzene in <br /> groundwater were reported at 120 pg/L and 0 96 pg/L, respectively in samples collected from <br /> MW-18D <br /> In order to decrease the risk of moving the plume in Unit B, we set the flow rate for AS-26 at <br /> approximately 30 percent of maximum when we restarted the AS system in June 2004 After <br /> evaluating the groundwater results from samples collected on July 13, 2004, we reduced the <br /> flow rate for AS-26 to approximately 15 percent of maximum capacity We believe that this <br /> setting will allow us to <br />' 1 Meet the CAO requirement for sparging in all aquifer units <br /> 2 Limit the potential for moving the plume in Unit B <br /> Between September 2002 and August 2003, low level to non detectable concentrations of <br /> TPHg and benzene were reported in wells MW-14 and MW-18D During this same period, the <br /> ASISVE system was operated continuously Sparging activities may have increased the <br /> concentrations of dissolved TPHg and benzene in the vicinity of wells MW-14 and MW-18D In <br /> order to monitor the plume movement in Unit B more effectively in the future, ENSR <br /> recommends adding wells MW-14 and MW-18D to our monthly sampling program Samples <br /> from wells MW-14 and MW-_18D will be analyzed for TPHg and benzene <br /> 1OcSaMmentolpm)ectsTrojects10694015098-2931FinaRReporEslWork PlansW%Work Plan-SVE AS System doc <br />