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6_ R604 •UPDATE 18 5-12-1993 sample . A small dedicated needle attached to a dedicated 1 cc syringe is then inserted through the sample septum into the 3 tedlar bag The 1cc syringe is purged numerous times before filling it with the sample. All but 0 5 cc of the sample is effected into the air before injecting the remaining 0 5 cc syringe sample into the Shimadzu FID-GC (the calibrant in3ection is 0 5 cc) . Once the chromatogram is recorded, an instrument blank is run prior to the next sample The instrument blank will indicate if residual peaks are being carried onto the next analysis . Vacuum influent readings are obtained from the wells by attaching a manometer calibrated in mm water to sample ports at the well heads These readings show the mm water pressure or vacuum that is being created at each well SUMMARY Estimates of petroleum hydrocarbons remaining in the soil after the confirmation soil sampling that occurred on July 20 , 21, 22, 1992 was approximately 3027 pounds . Soil sample results from the SB4 confirmation, sample boring and vapor samples from the vadose zone well P1 have indicated that the former northeastern pump island area and the surrounding area (AREA C) is now remediated of the contaminant The two remaining areas of impacted soil are AREA A - (SB5) the area beneath the former western pump island and AREA B (SB3 , SB9 and SB11) the area southeast of the former underground storage tanks ; Vapor extraction has removed the lighter fractions of gasoline range hydrocarbons found in the soil and has greatly reduced the dissolved contaminant found in the ground water and the capillary fringe Of the estimated 3027 pounds that remained in the soil after the July 22, 1992 sampling, 166 out of an estimated 72 pounds have been removed from AREA A and 2967 out of an estimated 2946 5 pounds have been removed from AREA B . This leaves approximately 200 5 pounds of degraded gasoline range hydrocarbons to be removed from the soil in AREA B as of April 15 , 1993 . This indicates that the majority of degraded gasoline range hydrocarbons has been from the soil and ground water at this site Dual instruments, GC FID and GC PID, have confirmed that benzene is no longer a component of the vapor streams Continual monitoring of the ground water indicates that the once contaminated ground water associated with MW1 and MW5 has been remediated and meets the Title 22 and DHS standards Ground water gradients, corrected for vacuum influence, have shown ; potentiometric lows at the wells being used for vapor recovery (MWS) . Once the vapor recovery is shut off, normal flow directions again take place to the east-southeast or northeast; 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 located east of the site . r . Fecal coliform has been analyzed for monitoring wells MW3 , MW4 , MW5 and MW6 on a monthly basis from December, 1991 through page 6 r E