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' 306620 Project Team <br /> March 28, 2007 <br /> ' Page 3 <br /> Table 2 <br /> ' Pressure and Air Flow Rates Measured on February 6, 2007 <br /> —Air—Sparge Pressure at Pressure at Pressure Flow at the Flow in the <br /> Well the well head the compound drop in the wellhead compound <br /> (psi) (psi) conveyance (SCFM) (SCFM) <br /> line (psi) <br /> ' —WW-11(with 24 26 2 27 >40 <br /> VIEW-11 also <br /> ' open) <br /> VEW-11 (With 21 23 2 17 >40 <br /> ' VEW-8 also <br /> open) <br /> All Wells 60 Approximately <br /> ' Closed 30 <br /> on February 20, 2007 ENSR personnel attempted to measure the air flow in sparge wells on the north <br /> ' side of Robinhood Drive(MW-19S, MWA 9D, MW-23S, MW-25S, and MW-25D), in the vicinity of the <br /> former Unocal station. Air flow rates could not be measured directly at the individual sparge wells as a <br /> ' result of space and piping configuration limitations. To quantify the flow rate at each well, the total flow <br /> rate was measured at the remediation compound with a single sparge well open. The well was then <br /> closed while the flow rate was measured at the remediation compound. The difference in flow rates was <br /> assumed to be the flow rate into each individual sparge well. During field measurements, no change in <br /> ' flow was measured when the wells were closed. The entire flow rate measured is assumed to be a leak <br /> in the sparge line network. Field observations from the February 20, 2007 field event are summarized <br /> below: <br /> • MW-23S (screened 86 to 91 feet)–Air flow in the compound, with MW-23S open, was <br /> measured at 50 SCFM. When well MW-23S was closed, no change was observed. <br /> ' Approximately 35 psi was measured at the wellhead with the sparge well open (40 psi in the <br /> compound). When the compressor was turned on, the pressure steadily increased to 35 psi at <br /> t the wellhead, and remained steady at 35 psi. There was no drop in pressure indicating that <br /> breakthrough had occurred. The compressor may not be delivering enough pressure to <br /> displace the water in well MW-23S and achieve breakthrough; the top of the screen interval is <br /> ' 86 feet below the ground surface (bgs) and depth to water typically measured at 32-35 feet bgs. <br /> The theoretical minimum air injection pressure for MW-23S is estimated to be 27 psi, with the <br /> fracture pressure calculated at 63 psi. <br /> ' MW-25S (screened 25 to 45 feet)–During the field tests, no pressure was observed at the well <br /> head, which indicated that this well is not connected to the AS piping network. Additionally, <br /> ENSR personnel started the SVE system to confirm that MW-25S is not connected to the SVE <br /> ' system. MW-25S is not connected to either the SVE or air sparge system. <br /> A Trusted Global Environmental,Health and Safety Partner <br /> ' Sparge Flaw Rate <br /> Summary_Stockton_306620 Final.doc <br />