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i <br /> 16 Working 7o Restore Nature <br />' Report on Vapor Extraction Test January 29, 1993 <br /> Coca-Cola Former Distribution Facility, Stockton, California 54006.01 <br /> after vapor concentrations under the tank pit have been reduced, all three wells will be <br /> brought on line <br /> o The amount of TPHg in the site soil has been estimated at about 9,560 lb During the <br /> first month of VES operation, the TPHg removal rate with one well on line is estimated <br /> at 1,068 lb TPHg During month two, with all three wells on line, the removal rate is <br /> estimated at 2,130 lb Based on RESNA's experience and other data (Shell <br /> Development, 1990), during about the third or fourth month of operation, the mass <br />' extraction rate for TPHg is predicted to drop about 90%, and will continue to slowly <br /> decline to nondetectable extracted vapor concentrations <br /> o Estimated operation time for the vapor extraction system is projected to be about 12 to <br /> 15 months until petroleum hydrocarbon vapors in the extracted gas stream are <br /> consistently nondetectable At this point it is estimated that about 90% of the TPHg <br /> will be cost-effectively removed from the soil (Shell Development, 1990) <br /> o A soil vapor extraction system is estimated to reduce diesel soil concentrations by less <br /> than about 30% after 12 to 15 months of VES operation If groundwater quality does <br /> not come into compliance within about one year after the VES is shut down, then <br /> groundwater remediation may be necessary Groundwater remediation is anticipated <br /> to be more cost-effective than excavation and disposal of the diesel impacted soil <br /> o It is RESNA's understanding that Coca-Cola has purchased a thermal oxidizer for this <br />' site According to the Remedial Action Plan (USTEC, September 1991) it has a peak <br /> flow of 600 cubic feet per minute (cfm), with a vacuum of 12 inches of mercury (163 <br /> inches of water), and a 40 horsepower regenerative blower This is more than adequate <br />' to meet the proposed design conditions The thermal oxidizer will most likely be <br /> permitted for the full 600 cfm air flow to allow for additional intake air to maintain the <br />' proper oxygen/vapor ratio for thermal oxidation and, if needed, to add additional vapor <br /> wells to the system at a future date Final permuting conditions will be determined <br /> during the design and permitting phases of the project <br /> 1 <br />' 18 <br />