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1 the 1987 excavation was sufficiently addressed by the SVE system that operated at the site and that the contaminant mass in the vadose zone was ' negligible The CPT groundwater investigation was used to assess the vertical extent of petroleum hydrocarbon impact at the site Based on the data obtained, PSC conservatively estimates that the vertical extent is approximately 90 feet bgs Although, the relatively higher petroleum concentrations appear to occur at depths shallower than 70 feet bgs PSC reported the results from the investigation in the June 2004 Site Investigation ' Report Additionally, groundwater samples were collected from all of the on- site monitoring wells and two nearby private wells Tlus groundwater- monitoring event indicated that the lateral extent of impacted groundwater is Ilargely contained within the Earthgrain's property boundaries In addition, historical and current decreases of petroleum impact to groundwater have been observed Based on the findings of this investigation, PSC recommended one more groundwater-monitoring event be performed, in which groundwater samples would be collected from wells MW-1, MW-5, MW-7, MW-8, MW-10, MW-11, MW-12, SP-1, SP-2, SP-4, SP-6, PZ-1, and PZ-2 Although, the samples would not be analyzed for EDB, since it was not detected during the investigation Upon completing the next quarterly event, ' PSC would prepare a report and propose either site closure or additional remedial work SJCEHD approved the recommendations in a letter dated September 24, 2004 Although, they requested that the remaining wells MW- 2, MW-3, MW-4, MW-6, MW-9, and MW-13 be placed on the annual groundwater monitoring program to track the plume SJCEHD requested that the quarterly depth-to-groundwater and total-depth measurements be performed in all wells They also requested that the following quarterly report include contaminant-mass-estimates and fate and transport models for dissolved gasoline and benzene The October 2004 quarterly groundwater-monitoring event indicated that the groundwater elevation decreased approximately 2 76 feet from the previous I event performed in June 2004 During this event, the average depth to groundwater was 48 68 feet bgs (-32 01 feet msl) The groundwater flow was easterly to southeasterly at a gradient approximately 0 003 feet per linear foot 1 Benzene concentrations increased in wells MW-1, MW-7, MW-11, MW-12, SP-1, and PZ-2 TPH-g concentrations increased in wells MW-11, MW-12, SP-1, SP-4, and PZ-1 DIPE was the only oxygenate detected The October _ 2004 report included the current calculations for residual mass of benzene and TPH-g in groundwater The calculated total mass of benzene in groundwater was 18 Kilograms (Kg) and the calculated total mass of TPH-g in groundwater was 70 7 Kg Fate and transport models for benzene and TPH-g were presented, as well The model for benzene predicts that the concentrations decrease rapidly to levels less than the Maximum Contaminant Level (MCL) at a conservative distance of 30 feet from the source The model indicates that the concentration of benzene may exceed its associated 4 Quarterly Groundwater Monitoring Report 4th Quarter-November 2005 Prepared for SARA LEE BAKERY GROUP,INC Prepared by PSC Environmental Services Investigative and Quarterly Report h 4th Quarterly Report 11_2D05 doc February ry24,2006