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R604 :UPDATE 10--JUNE, 1992 1 17E) and then is pulled into the pumps (two Rotron DR505 placed in . series ) prior to entering a second moisture drop out drum and then onto activated charcoal vapor scrubs. If breakthrough was found to be occurring through the 1st carbon, this carbon was removed from the system, the #2 carbon was then placed into the #1 position and a new carbon placed on the exhaust as the #2 carbon. To prevent the vapor extraction system from being shut down due to using up all of the carbon scrubs , a vapor stream - condensate unit was used (CYCLO-PURGE) to re-3uvinate the spent carbons so that they could be placed back on line. This unit was able to remove approximately 20-25 percent of the absorbed hydrocarbons from the carbon scrubs as water and gasoline condensate , which was stored on site in 17H hazardous material drums along with the rinsates and purged well water . The recovered gasoline was eventually removed to Wicklands Terminal in Selby, CA. , for blending, see Table 4 Update Status Report #8 . Once the system was turned off all 10 carbon scrubs were sent to Cameron Yakima for rejuvenation, see Appendix D-Manifest. i j A portable ambient air PID-GC (Photovac 1OS50 packed column) is used at the site to sample for breakthrough of the carbon scrubs , the influent and effluent of the system, and the influent from the various vapor extraction wells . Prior to sampling the wells or the system, a calibrant prepared from fresh gasoline is inDected 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 , which is used to calculate mg/L as gasoline vapor from each analysis produced. Using these mg/L values produced from the analysis of the Ci different vapor recovery wells , the pressure differential created at the orifice to determine flow rates for each well , and the influent values ; pounds per day can be computed. The pounds per day values for each well and the influent are then averaged to the preceding 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 total system have 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. SAMPLING VAPOR STREAMS The vapor samples are obtained by attaching a dedicated air tight 60 cc syringe and soft polytubing to a sample port on the well side of the orifice plate on vapor recovery manifold. 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 tilled, the sample valve closed and forceps 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 . page 6