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R603 UPDATE-12 12/22/92 recovery (32 , 653 pounds/6 .25 pounds/gallon = 5224 . 5 gallons) and vapor extraction-destruction of hydrocarbons (48310 pounds/6 25 = 7729 6 gallons) No chlorinated solvents were detected in chromatogram comparisons , "i .e. " 1, 2, -Dichloroethane (DCE) - retention time 2 . 079 minutes, Trichloroethylene (TCE) - retention time 3 . 023 minutes and Tetrachloroethylene (PCE) - retention time 3 75 minutes Figure 7 represents lateral extent of vacuum influence from measurements obtained during the quarterly ground water monitoring round on December 9, 1992 . Figure 7 shows that the vacuum extraction, along with the twice weekly purging of monitoring wells MW1, MW2, MW3 , MW8 and MW10 , is influencing the removal of contaminants associated with the soil and ground water 4 . 0 DISCUSSION AND CONCLUSIONS As stated in earlier reports, the soil is contaminated with gasoline range hydrocarbons beneath the tank field (MW10) and along the capillary fringe of the ground water, (MW1, MW2, MW3 and MW10) , see Figure 6 Ground water beneath the site contains the dissolved constituents of gasoline range hydrocarbons and had spread to the north (MW-6) , to the south (MW--7) to the west (MW- 9) and to the east (MW-12) . The latest ground water sampling, December 9, 1992 , shows the continual decline in the lateral extent of the plume, see Table 1 and Figures 5A and 5B Vapor extraction started October 17, 1991 and has operated for 5388 hours (December 18 , 1992) out of a possible 8821 5 hours, 61% run time, destroying 48310 pounds of gasoline range hydrocarbons Since the last status report, November 17, 1992 , 8768 pounds of gasoline range hydrocarbons have been removed/destroyed and an estimated 6573 pounds of oxidized hydrocarbons as CO2 removed (averaged 1 451 in influent stream) in 614 25 hours of operation (averaging 24 98 pounds per hour or 599 pounds per day of operation) DCE, TCE and PCE screening show that these compounds are not present in the vapor stream, see Appendix B - Air Monitoring Report and Table 5 Ground water elevation measurements show the ground water has started a recharge cycle, which is normal for this site during this time of the year, with a valley forming from MW3 towards MWl and MW5 , while the overall flow direction is to the southeast from the tank area towards monitoring well MWS Results of ground water samples collected on December 17, 1991, approximately 1473 hours after commencement of vapor extraction, compared to the results of ground water sample collected on December 9, 199? , 9355 5 hours (390 days) after commencement of vapor extraction, show a decline in the extent of the dissolved constituents in all of the monitoring wells, see Table 1 All floating product has been removed PAGE 9