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IFormer Canteen Facility July 1,2004 Quarterly Groundwater Monitonng Be ort Page 5 the soil and groundwater On June 4, 2004, SVE well VE-2 was shut-off to further increase vacuum levels on the remaining two SVE wells The following Table summarizes the operating parameters of the system during these various stages I Vacuum Levels in w c Overall Well Flow scfm Wells in Operation Minimum Maximum Minimum Maximum All Five Wells 20 70 70 13 VE-1, 2, & 3 60 49 28 46 VE-1 & VE-3 45 75 12 43 An Internal Combustion Engine (ICE) unit provides the vacuum for the SVE system and also I treats the hydrocarbon vapors recovered from the subsurface The unit operated with total flows that varied from 37 7 to 47 6 standard cubic feet per minute (scfm) ICE unit operations were supplemented with liquid propane gas (LPG), to assure efficient operations The destruction I . efficiency of the ICE unit varied from 80 3 to 99 8 percent (%) as shown in Table 3 After the down-gradient SVE wells were temporarily removed from service, the LPG consumption reduced from approximately 1 7 to 15 scfm or 2 7 to 2 4 gallons per dour(gph) IOperation and maintenance activities for the sparge/vent remediation system are conducted weekly Vacuum and flow readings from the individual vapor extraction wells are measured and recorded along with total vacuum and flow readings from the ICE unit Influent and effluent vapors from the ICE unit are measured weekly using a photoionization detector For the first six weeks of operations, influent and effluent samples were collected biweekly in Tedlar bags and I submitted to McCampbell Analytical, Inc in Pacheco, California for analysis of TPH(g) and BTEX/MTBE concentrations via Modified EPA Methods SW846-8015G and SW846-8021, respectively Starting in June 2004, the frequency of sampling for laboratory analysis was ' reduced to monthly The influent is analyzed for BTEX/MTBE concentrations and the effluent is analyzed for TPHNOC concentrations The analytical results are summarized in Table 3 Hydrocarbon (TPHNOC) recovery rates varied from 0 167 to 1 851 pounds per hour (lbs/hr) during the period from March 24 to June 16, 2004 In addition, a total of approximately 1,453 pounds of petroleum hydrocarbons have been extracted and treated by the ICE unit, as Isummarized in Table 4 The hydrocarbon recovery rates and cumulative hydrocarbon recovery are illustrated in Graph 1 During this period of operation, oxygen influent levels increased from 8 6 to 17 % and carbon dioxide concentrations decreased from 7 9 to 3 2 percent I 1