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REG 603 UPDATE-6 2/21/92 • influent are then averaged to the preceeding site visits pound per day and then multiplied by the number of days the system operated between visits to estimate the total pounds each well and the system has removed for that time period. This poundage is then added to the accumulated poundage of the previous visit to update the total pounds removed to date. The effluent sample is computed in the same fashion, but also includes natural gas flow along with the influent orifice flow rate. 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, 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 times filling and depleting the syringe of that particular wells vapor stream. Then the syringe is filled, the sample valve closed and forcepts are used to clamped 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 forceps clamped polytubing attached, the plunger is 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 suringe is then inserted into the 60 cc syringe via the soft tubing for obtaining the sample to be injected into the PID-GC. Again the lcc syringe is purged numerous times prior to filling it with the sample. All but 0 . 5 cc of the sample is effected into the air prior to infecting the remaining 0. 5 cc syringe sample into the GC-PID (the calibrant infection 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 zhe 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 in mm water to samnle ports at the well heads_ These readings show the mm water pressure or vacuum that is being created at each well. VAPOR RECOVERY OPERATIONS AND RESULTS As has been stated above, soil contamination exists from beneath the tank excavation to the top of the ground water. Overexcavation during the intaal tank removal, removed contaminated soil to the 25 foot depth. Prior to replacement of the new double contained fiberglass tanks and dispensing system, 4 inch and 6 inch SCH 40 PVC 0 .02 inch slotted pipes were placed PAGE 9