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3.0 VAPOR EXTRACTION SYSTEM OPERATION AND MONITORING t3.1 System Operation As reported in the previous quarterly report, dated October 16, 1995, the extraction system was shut ' down for one month in the third quarter in order to allow the soil to "relax" and vapor concentrations to increase After the system was restarted in September, it operated erratically at flow rates near or above 40 cfm for the remainder of the third quarter Flow was therefore restricted to the 30-37 cfm t range During that quarter, the system operated for 1,115 hours, during which a total of over 2,600,000 cubic feet of vapor were withdrawn ' In October and November, Apache continued to have difficulty in achieving air flow rates above 40 cf n At higher flow rates, the RPM'S fluctuated considerably and the unit vibrated noticeably The unit performed considerably better during December, and flow rates above 40 cfm were the norm During ' the quarter, the system operated for a total of 1816 hours (Appendix A) It operated for 30 days in October, 26 days in November, and 30 days in December During that period, 4,262,940 cubic feet of vapor were extracted This brings the total to over 40,000,000 cubic feet since July 1994 ' 3.2 Monitoring Summary ' The extraction unit's on-board computer monitors several important parameters of engine performance, including air flow rates, well vacuum, and volume of extracted vapor These data are recorded hourly and averaged over the 24-hour day Hydrocarbon concentrations in the vapor stream (influent soil gas) and effluent (combustion products) ' were manually monitored on a weekly basis with a Mcrotip HL2000 photo-ionization detector In addition, one vapor sample was collected from the combined influent line on December 14 for comparison to the PID reading on that date The sample was collected in a tedlar bag and delivered to ' Sequoia Analytical for analysis of TPH-g, BTEX, 02, CO2, CH4, and N2 concentrations in the vapor stream ' PID readings at the exhaust port ranged between 1 and 9 ppm throughout the quarter PID readings in the inlet stream ranged from a high of 2,380 ppm in the deep well in mid-November to a low of 103 ppm in this well in late December 4.0 DATA ANALYSIS ' 4.1 Graphical Summary r3' ' Monthly summaries of daily air flow rates and other parameters for the fourth quarter are included in Appendix A In order to graphically illustrate the operation of the system, data for air flow rate and total cubic feet of extracted vapor since September 1994 are plotted in Figures 3 and 4 PID readings 1