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UPDATE 28 8-02-94 into the GC-PID The resulting chromatogram has numerous responses The microprocessor of the GC-PID computes the area Per response in volt seconds, and assigns a peak number and retention time The sum of all the responses are then used to obtain a mg/L per volt second calibrant factor This factor is used to calculate mg/L as gasoline vapor from each analysis Pounds per day can be computed using these mg/L values, and the pressure differential created at the orifice (flow rate) for each well Since September 25, 1992 , tedlar bag samples are obtained and brought back to be analyzed in the WEGE portable laboratory This is necessary due to long eluting time (analysis time increased from 10 minutes per sample to 30 minutes per sample) needed per analysis using the 10s50 (all early eluting compounds have been removed by vapor extraction) . The pounds per day values for each well are then averaged to the corresponding values from the preceding site visit and then multiplied by the number of days the system operated between visits to determine the total pounds removed for each well and for the total system 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, see Table 3 and Appendix C Sampling Vapor Streams. The vapor samples are obtained by attaching a dedicated air tight soft polytube to a sample port on the well side of the orifice plate on the vapor recovery manifold. The tubing is then connected to a tedlar bag placed inside a vacuum sampler The sample port is then opened A vacuum placed on the outside of the tedlar bag from the sample vessel allows the tedlar bag to fill with the vapor stream from that particular sample port once the tedlar bag is full the valve is closed and the vacuum removed from the sample vessel The tedlar bag contains an air tight locking septum valve which is then closed and locked to secure the vapor sample A small dedicated needle attached to a dedicated 1 cc syringe is then inserted through the sample septum into the tedlar bag The 1cc syringe is purged numerous times before filling it with the sample All but 0 5 cc of the sample is ejected from the syringe, into the air before injecting the remaining 0 5 cc syringe sample into the Shimadzu FID-GC (the calibrant injection is 0 5 cc) once the chromatogram is recorded, an instrument blank is run prior to the next sample The analysis of the instrument blank will verify that no residual peaks are being carried onto the next analysis Vacuum influence 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 page9