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R603 UPDATE-10 11/09/92 SAMPLING VAPOR STREAMS The vapor samples are obtained by attaching a dedicated air tight 60 cc syringe to a sample port on the vapor recovery manifold (on the well side of the orifice plate) with air tight fitted polytubing. The sample port is then opened and the syringe is purged by pulling and pushing the syringe plunger several tames filling and depleting the syringe of that particular well ' s vapor stream. Then the syringe is filled, the sample valve is closed, and forceps are used to clamp onto the soft polytubing to create an air tight seal for the syringe before removing the syringe from the sample port. Once the 60 cc syringe is removed with the clamped polytubing attached, the plunger as pushed into the syringe to create pressure within the syringe and released to allow the vapors that have been captured to reach equilibrium. A small dedicated needle attached to a dedicated 1 cc syringe is then inserted into the 60 cc syringe via the soft tubing for obtaining the sample to be an3ected into the PID-GC. Again the 1cc syringe is purged numerous times prior to filling it with the sample. All but 0 . 5 cc of the sample is e3ected into the air prior to an]ecting the remaining 0 . 5 cc syringe sample .into the GC-PID (the calibrant in3ection is 0 . 5 cc ) . Once the chromatogram has been 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. While the GC-PID analysis is running for a particular sample ( 15 minutes per sample run) , vacuum influent readings are obtained from the wells by attaching a manometer calibrated an 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. Occasionally the 10S50 PID-GC is not available for field determination of the influent and effluent streams. Tedlar bag samples are tihen onzained and brought back to the WEGE portable laboratory for analysis using a FID--GC, see Appendix C - Field Notes. VAPOR RECOVERY OPERATIONS AND RESULTS As has been stated an earlier reports, soil contamination exists from beneath the tank excavation to the top of the ground water, see Fence Diagram Figure 6 . Overexcavation during the -initial tank removal , removed contaminated soil to the 25 foot depth. Prior to replacement of the new double conta-Lned f.Lberylass Lanks and dispensing system, 4 inch and 6 inch SCH 40 PVC 0 . 02 inch slotted pipes were placed vertically at the north corner and west corner . of the excavation respectively and manifolded via underground to the treatment compound with SCH 40 2 inch and 4 inch PVC pipe. PAGE 7