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R604 :UPDATE 10-JUNE, -1992 Pounds , MW5 = 8810 . 7 pounds and MW3 = 11 . 53 pounds , see Table 3B. Vapor extraction has greatly reduced the dissolved contaminant found an the ground water . The March 5 , 1992 sampling occurred 80 days after the vapor recovery system was shut down and showed that since va or recover has been used at this site, MW1 has been EIi reduced from 2 mg/L TPH to <0 . 05 mg/L TPH. MW5 , likewise has been reduced from 31 mg/L TPH to 0 . 08 mg/L TPH. The BTEX's have also been removed from the ground water beneath the site to below the detection limits . Vapor extraction was resumed on March 31 , 1992 and has operated 1507 hours prior to sampling on June 2, 1992 . The sample analysis for the June 2 , 1992 sampling is below detection limits for all constituents analyzed for (TPH-g, BTEX) , see Table 2A. Ground water gradients , corrected for vacuum influence, have shown potentiometrzc lows at the wells being used for vapor recovery; MW1 and MW5 . Once the vapor recovery is shut off , normal flow directions again take place to the east-southeast; with the exception of the March 5 , 1992 gradient, which flowed to the north northwest and may represent a recharge and/or a decline in water usage of the municipal wells to the east of the site. Fecal coloform has been analyzed for monitoring wells MW3 , MW4 , MW5 and MW6 on a monthly basis from December , 1991 through t February, 1992 . Only trace amounts of fecal coloform have been occasionally detected in any of the wells during those 3 months , this analysis will occur on a quarterly basis starting on the June, 1992 ground water sampling, see Table 2B. RECOMMENDATIONS 1 . The Permit to Construct has been obtained. As requested in the permit, twice weekly sampling of the effluent is to occur for the first month then monthly thereafter . Continue vapor recovery on MW1 and MW5 to continue ground water remediation. i 2 . Continue to monitor this site on a quarterly bases . I 3 . Obtain depth to ground water , vacuum influence readings to evaluate the effects of vapor recovery. 4 . Sample for fecal coliform from MW3 , MW4 , MW5 and MW6 k on a quarterly basis during the quarterly sampling. 5 . Perform monthly monitoring and sampling of the vapor stream using the GC-PID 10 S 50 chromatograph and include the results in a monthly update status report. 6 . Drill three confirmation sample borings , one near P3 , • one near P1 and the other near SB-2 , to obtain soil page 9 I I i