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4 SUMMARY AND RECOMMENDATIONS <br /> 4' Groundwater-monitoring has been conducted at this facility since 1999 to evaluate <br /> groundwater quality A summary of the current site conditions and a <br /> recommendation for subsequent work are as follows <br /> • During this event, the average depth to groundwater In the wells was 28 68 <br /> feet bgs (-18 91 feet msl) The groundwater flow was generally easterly at a <br /> gradient of about 0 005 foot per linear foot <br /> • Low levels of xylenes and TPH-G were detected In the sample collected from <br /> 7 <br /> well MW-2 In March 2005 Benzene, toluene, ethylbenzene, and oxygenates <br /> were not detected In well MW-2 <br /> + The concentrations of petroleum hydrocarbons decreased In well MW-2, since <br /> the previous event <br />!' • The current BTEX concentrations were evaluated against the California <br /> Drinking Water MCLS Based on the current groundwater-monitoring data, <br /> I' the concentrations were less than MCLs <br /> • BTEX, TPH-G, and oxygenates were not detected In any of the remaining <br /> 4� wells <br /> ® The SVE system was placed back Into operation In the "pulse" mode on <br /> li December 15, 2004 The March 2005 groundwater sampling event occurred <br /> while the system was engaged The groundwater contaminant concentrations <br /> decreased from the previous event upon engaging the remediation system <br /> 1 • The current total mass of TPH-G removed from the soil Is estimated at 173 <br /> pounds, which Is approximately 51% of the Initial estimated amount The <br /> current mean Influent rate of TPH-G was 5 04 lbs/day, wlule the average <br /> emission rate after treatment was 0 17 lbs/day Therefore, the VOC removal <br /> efficiency was approximately 96 6% <br /> Based on the results of the March 2005 sampling event, It appears that further <br /> P g <br /> groundwater remediation Is warranted at the facility PSC recommends that the <br /> current quarterly groundwater-monitoring plan and the air sparging/soll venting <br /> continue as Is <br /> 1 <br /> to <br /> Quarterly Groundwater Monitoring Report <br /> March 2005 <br /> Prepared for SARA LEE BAKERY GROUP,INC Prepared by Philip Services Corporation <br />' Investigative and Quarterly Report\15t Quarterly Report 03_2005(final) September 23,2005 <br />