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VAPOR SAMPLING On site sample analysis is performed using a Photovac 10550 PID chromatograph. r 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 thatp articular wells vapor stream. Then the syringe is filled, the sample valve closed and forceps are I clamped onto the soft polytubing to create an air tight seal for ithe 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 injecting the remaining 0 .5 cc syringe sample into the GC-PID {the calibrant xn]ection 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 . The resulting chromatogram is then compared to a standard calibration run on the same chromatograph prior to the sample run. 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 sample ports at the well heads . These readings show the mm water pressure or vacuum that is being created at each well . COLLECTING LABORATORY SAMPLES INFLUENT SAMPLE The influent sample is obtained from a sample port located after the system vacuum pump before the carbon canisters . Sterile poly tubing is then used to attach a 1 liter tedlar bag, fitted with a special septum "valve" and tubing bib, to the sample port. The sample port is on the pressure side of the pump and therefore the bag will fill without need of a pump. Once the tedlar bag is filled, its ' valve is closed and locked; the appropriate label is placed on the tedlar bag. R604 vapor, 6/19/92 , p. 4