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tl • First Quarter 1996 Status Report - Unocal Station No #6981 April 25, 1996 #1210) Copies of the Sequoia reports and cliam-of-custody documents are presented in Appendix B Between December 19, 1995 and March 26, 1996 the VES operated approximately 59 days, or 60% of the time Soil vapor was extracted from wells VW-1, VW-2, and VW-4 through VW-6 during the first quarter 1996, as field monitoring indicated these wells had the highest hydrocarbon concentrations During the March 26 site visit, well VW-6 was shut off and the system is currently extracting from wells VW-1, VW-2, VW-4, and VW-5 I Chemical Analytical Data Collected samples were submitted to the Sequoia Analytical laboratories located in Walnut Creek, California (FLAP #1271) System monitoring data and chemical analytical data are summarized in the attached tables TPHg destruction efficiencies during this period ranged from 96 13 to 99 74 percent, and benzene destruction efficiencies ranged from 98 96 to greater than 99 81 percent During the first quarter 1996 the TPHg extraction rate ranged from 27 to 38 pounds per day (lb/day), while the benzene extraction rate ranged from 0 2 to 0 4 lb/day To date, approximately 7,345 pounds of TPHg and 161 pounds of benzene have been extracted and treated by the VES The VES continues to meet all SJVUAPCD permit conditions with regard to hydrocarbon destruction efficiencies and mass discharge rates WATER DISPOSAL Moisture from the influent vapor stream is collected in the knockout drum When the knockout drum is full, the water is transferred to a properly labelled drums for storage. On March 25, 1996, Armour Petroleum of Vacaville, California, removed approximately 212 gallons of stored water from the site The drums remain at the site for future water storage Copies of the Armour disposal confirmation sheets are attached in Appendix Cc SECOND QUARTER 1996 SCHEDULED ACTIVITIES Groundwater monitoring wells at the site will be monitored and sampled Groundwater samples will be collected from the perimeter wells during the second quarter sampling This work will be performed by MPDS and the Quarterly Data Report will be submitted to the appropriate regulatory agencies by MPDS on behalf of Unocal 4955027 3