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I IFormer Canteen Facility April 14,2005 uarterly Groundwater Monitoring Report Page_5 Iconducted weekly The weekly O&M activities included vacuum readings from the individual vapor extraction wells and overall inlet manifold were measured and recorded, along with total flow readings from the ICE unit The following table summarizes the operating parameters of the system during this quarter. Vacuum Levels Overall Well Flow HC Concentrations Operating scfm µ P Wells Minimum Maximum Minimum Maximum Minimum i Maximum VE-1 & VE-3 27 68 26 f 40 6,500 II 8,400 I i The ICE unit operated with total flows that vaned from approximately 36 to 42 standard cubic feet per minute (scfini) ICE unit operations were supplemented with liquid propane gas (LPG), I to assure efficient operations LPG consumption varied from approximately 158 to 188 scfrn or 2.6 to 3 1 gallons per hour (gph) Further details of recorded system data and operating parameters are summarized in Table 3 IHYDROCARBON VAPOR MONITORING I Influent and effluent vapor concentrations from the ICE unit were measured weekly using a photo-ionization detector (PTD) During this period of operation, oxygen (02) and carbon dioxide (CO2) influent levels were also monitored periodically Generally speaking, 02 levels increased and CO2 levels decreased during this monitoring period During the first weekly O&M visit each month, influent and effluent vapor samples were collected in Tedlar bags These samples were express-delivered 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 The destruction efficiency of the ICE unit vaned from 87 0 to 99 8 percent (%) The analytical results are summarized in Table 4 Hydrocarbon (TPH/VOC) recovery rates primanly vaned from 0 866 to 2 064 pounds per hour (lbs/hr) during this monitoring period In addition, hydrocarbon vapors in excess of approximately 21,600 pounds (3,450 gallons) have been recovered and treated by the ICE unit, as summarized in Table 5. The hydrocarbon recovery rates and cumulative hydrocarbon recovery Iare illustrated in Graph I AIR SPARGING OPERATIONS Air sparging (AS) operations were interrupted for a portion of the quarter, due to an inoperative air compressor unit Operations were re-initiated on March 18, 2005 Since VE-I and VE-3 are I the only current SVE wells in operation, AS operations have been limited to the northern AS sections These sections cover AS wells AS-1 through AS-6 and are comprised of two AS wells each The delivery pressures have been approximately 4 to 5 pounds per square inch gauge I (psig), with flows varying from about 10 to 1 5 scfin for each section (--0 50 to 0 75 scfm per well) I