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1 S ' I i Groundwater Flow Direction: South-southeast Groundwater Gradient: 0.001 ftlft } SVE SYSTEM QUARTERLY OPERATION AND PERFORMANCE Equipment Inventory: 2.3 HP Fuji Blower, two 1,000 Ib carbon vessels i Operating Mode: Operational APCD Permit No.: N-4887-1-0(ATC) _ Influent TPHG Concentration End of Period: 16 Mg/M3 + Influent Benzene Concentration End of Period: X0.15 mg/m3 i Flow Rate End of Period: 45.3cfm } HC Destroyed this Period (lab): 181 lbs Cumulative HC Destroyed: 3682.89 lbs. I Percent Time Operational: 75(average) DISCUSSION: i i At the time of the first quarter 2004 monitoring event, groundwater elevations had increased between 1.92 and 2.12 feet since the previous sampling event (October 21, 2002). Depth to water measurements were normalized to mean sea level (MSL), and were used to construct a groundwater elevation contour map (Figure 2). The groundwater elevation in well S-2 appeared anomalous and was not used in contour construction. The groundwater flow direction on January 7, 2004, was calculated to be towards the south-southeast at an average gradient of 0.001 ft/ft. South-southeast groundwater flow direction has ( � consistently been observed during previous monitoring events. TPHG (240 pg/L) and MTBE (110 µg/L) were reported in well MW-8. Benzene was not reported in any of the wells. TBA was reported in wells MW-1 through MW-4, and MW-6 through MW-10 with the highest r concentration (56 µg/L) reported in well MW-8. BTEX, DIPE, ETRE, or TAME were not reported in any of + h the wells: Analytical results from the January 7, 2004, sampling event are generally consistent with historical analytical data. TPHG, benzene, and MTBE data have been summarized on Figure 3. On February 11, 2004, Stratus conducted a carbon change-out. The SVE system was re-started on f Februarys 17, 2004 to verify system'airflow rates and then shut down. The system was restarted on February19, 2004, and samples were collected. The system was shutdown on March 12, 2004, as TPHG l was repo4ed in the midfluent air sample collected on March 11, 2004. { Between February 11 and March 12,2004, Stratus conducted seven site visits to operate and maintain the SVE system, and to collect the compliance air samples. The SVE system extracted approximately 181 pounds of TPHG during the first quarter 2004, and has extracted a cumulative mass of approximately 3682.89 pounds of TPHG since the first installation of SVE system (August 2000). On March 4, 2004, the { SVE system exceeded the 70cfm permit requirement by 5.9 cfm, the system was revisited on March 11, 2004, avid flow was recorded at 45.3 cfm. The destruction efficiency of the activated carbon system j k appears to be low due to high variations in influent soil vapor concentrations, Due to the high degree of fluctuation in influent soil vapor concentrations, Stratus proposes to reinstall a 100 cfm catalytic oxidizer at the site to extract and abate soil vapors. I I I` I PAUSA Gasoline10065%Qtrly120041USA_65_IQ04.DOC STRATUS I '3