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ENSR ' the pilot test indicated that VE would have little or no effect at the site due to a limited area of vacuum influence and a low rate of hydrocarbon recovery Extraction rates for VW-3 were between 0 01 to 0 8 pounds of TPHg per day with extraction rates for VW-1 and VW-2 between 0 01 and 0 7 pounds of TPHg per day GRI concluded the expected radius of influence would be less than 45 feet and decrease with time Therefore, VE would have little or no effect at this site March 2002 Monitoring wells MW-20 and MW-21 were installed and soil samples were collected at 5-foot intervals from each location All of the 7 soil samples analyzed for TPHg, benzene, and MTBE were non-detect Ozone sparge couplets SP-1 A/B/C, SP-2A/B/C, and SP-3A/B were installed between March 4---8, 2002 to depths of 30 (A-senes wells) and 60 feet bgs (B-series wells), and 90 feet bgs (C-series wells) April 2002 Monitoring wells MW-20 and MW-21 were sampled on April 11, 2002 TPHg, benzene, and MTBE were not detected in these wells August 2002 A C-SpargeTM ozone microsparging system began operation on August 14, 2002 Monitoring wells MW-2, MW-10, MW-11, and NP-1 have been monitored monthly to evaluate the effectiveness of the C-SpargeTM system February 2003 Groundwater sampling conducted on February 27 and 28, 2003 indicate that the groundwater flow for zone A continues to be in the northeasterly direction, however, the flow for zone B is in the southeasterly direction March 2003 Summary of monthly data collected at wells MW-2, MW-10, MW-11, and NP-1 from August 2002 through March 2003 indicate a final decrease in TPHg and benzene in all the wells monitored with the exception of an increase in benzene in well MW-11 April 2005 The San Joaquin Environmental Health Department(SJEHD) issued a letter to UNOCAL regarding the source of 1,2-dichloroethane detected in the groundwater (see Appendix B) The SJEHD did not find any records that other sites in the area were the source of the 1,2-DCA so they concluded that the source is from the UNOCAL site Groundwater monitoring and ozone microsparge system reports have been issued quarterly, documenting the on-going remedial and assessment activities performed on site Additional Enrormation describing the findings of site investigation activities and the progress of remedial actions is presented in Section 3 0 2-4 bird 5 {6