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MonWoring and MaIlrLenance of the VES The concentration of the extracted well vapors from the four vapor wells is monitored on 3 weekly basis using an OVA 128-GC and monthly using a SKID Sampling pump with SKC carbon tubes. The OVA 128•13C analyzes by flame ionization for total petroleum hydrocarbons as methane, The OVA 128-GC is calibrated to 96.5 ppm methane in zero gas air. The :XC Sampling Pump and SKC carbon tubes are used to provide laboratory verification of the individual gasoline constituents in the extracted well vapors. The SKID Pump is a calibrated industrial hygiene air sampling pump with digital floN and timing instrumentation. A volumetric vapor sample is obtained by inducing the flow of i the undiluted vapors from each of the individual vapor extraction wells across granular activated carbon which is contained in a pencil shaped glass tube. The activated carbon traps and adsorbs the hydrocarbon gases until the sample is analyzed at the laboratory by desorption with carbon disulfide followed by gas chromatographic analysis of the solution. The volume of the of the sample is determined by multiplying the flow rate of the sampling pump by the duration of the sampling event to obtain liters of air sampled. A typical SKID carbon tube sample is obtained by sampling the blower exhaust at one liter per minute for three to five rninutes to obtain a three to five liter sample. In this manner the vapor composition of the extracted well vapors can be determined for specific compounds such as benzene, toluene, ethylbenzene, total xylenes, or total petroleum hydrocarbons (TPH) as gasoline. Appendix li presents the analytical laboratory reports obtained from the SKID Tube analyses which are also summarized in Table 2. 4 VAPOR EXTRACTION TECHNOLOGY, INC.