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v T C A S S d C I A T E 5 I N C 4.5 Analysis of System Effectiveness Figures 14 through 20 are cross plots of benzene and MTBE over time. Figures 21, 22 and 23 show the areal distribution of the same analytes (i.e., benzene, MTBE and TPHg) respectively, based on isoconcentration maps over time. 4.5.1 Benzene ' Prior to remediation system start-up on June 17, 2004 at the Jamar property, benzene concentrations appeared to decline in MW2, MW3, MW4, MW5 and MW8. Declining trends in benzene concentration were not evident, however, in MWI and EWl prior to start-up. Benzene ' concentrations show an overall decrease in MW1 and EWI from start-up. During the first quarter monitoring period concentrations of benzene from MW1 and EWI ' placed respectively at approximately 7.5 and 9.0 feet from the closest Spargepoint® (respectively, IW2 and IWl) declined. The overall decline of benzene in MWl from the 37,000 ug/L on June 3, 2004 in each of the quarterly monitoring events following that event (i.e., September 13, 2004, December 13, 2004 and March 16-17, 2005) was significant. During the first quarter 2005 event, benzene was reported as not detected at method detection limits of 0.5 ug/L for a removal efficiency exceeding 99.9% after approximately 9 months of operation. rThe overall decline of benzene in EWI from the 35,000 ug/L on June 3, 2004 in each of the quarterly groundwater monitoring events (following that event) also was significant. Benzene also was not detected in EWI at respective method detection limits of 2.5 and 0.5 ug/L for the January 28, 2005 and February 22, 2005 system monitoring events and during the March 16-17, 2005 groundwater-monitoring event at method detection limits of 0.5 ug/L. During the March 16-17, 2005 event, a removal efficiency exceeding 99.9% was achieved after approximately 9 months of operation. During the first quarter monitoring period, concentrations of benzene from MW2 and MW4 also declined. Benzene in MW4 was reduced to a non-detection level (<05 ug/L) on December 13, 2004 and remained at that level through the two system events conducted in the first quarter and ' during the March 16-17, 2005 groundwater-monitoring event. Concentrations of benzene from MW3 fluctuated and the decline of benzene in MW3 does not appear to have accelerated after system start-up. ' MW4 is approximately 16 feet from the closest Spargepoint® (IW4). The decline of benzene in MW4 may have accelerated after system start-up from the 1500 ug/L on June 3, 2004 to later monitoring events (i.e., September 13, 2004, December 13, 2004 and March 16-17, 2005). During the March 16-17 2005 groundwater-monitoring event, benzene in MW4 was reported at a concentration of<0.5 ug/L. If this reduction was attributed solely to system activities this would ' equate to a removal efficiency exceeding 99.9% after approximately 9 months of operation. (Note: In addition, dissolved oxygen (DO) concentrations have increased notably in MW4 after system start-up. The increase in DO after system start-up would indicate influence by the C- SpargeTM process.) ' S:1268231QM reports12005 IstQR.doc 9