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System Operation Detains
<br /> The C-SpargeTM system was started on December 26, 2002, The C-Sparge7M control panel was
<br /> programmed and scheduled to inject ozone cyclically in each injection point for 14 minutes. Based on this
<br /> programming, each injection point will have ozone injection in 18 cycles for 4.2 hours every day.
<br /> During third quarter 2003 (between June 23, 2003 and September 29, 2003), a Stratus technician
<br /> conducted eight site visits to collect field parameters and laboratory parameters. The ozone injection
<br /> system indicated low injection pressures (15 psi) during site visit conducted on September 18, 2003 due to
<br /> a compressor malfunction. The ozone injection system was shutdown on September 18, 2003 pending
<br /> maintenance and replacement of parts on the compressor. The ozone injection system was re-started on
<br /> September 29, 2003 after repairing the compressor. Upon re-starting the ozone injection pressures
<br /> increased back to 30 psi. Field data sheets presenting field parameters collected between June 23, 2003
<br /> and September 9, 2003 are included in Appendix A, and certified analytical reports with chain-of-custody
<br /> documentation are included in Appendix C.
<br /> Ozone Inlection Monitoring Plan
<br /> Monitoring wells MW-3 through MW-10 are used as observation wells to monitor the performance of
<br /> ozone injection system. Monitoring wells MW-1 and MW-2 are used as background wells to evaluate and
<br /> monitor for natural geo-chemical changes in groundwater. The following field and laboratory parameters
<br /> will be monitored periodically to evaluate and optimize the performance of the ozone injection system.
<br /> Field Parameters (Bi-monthly): pH, Dissolved Oxygen (DO), and Specific Conductivity
<br /> Laboratory Parameters (Quarterly): TPHG, BTEX, five oxygenates, Chemical Oxygen Demand (COD),
<br /> Ferrous Iron, Total Iron, Total Organic Carbon (TOC), Nitrates, Sulfates, Phosphates, and Total Dissolved
<br /> Solids.
<br /> During third quarter 2003, field parameters were collected on a bi-monthly basis and laboratory
<br /> parameters were collected on a quarterly basis. Table 3 presents the sampling frequency, field and
<br /> laboratory parameters analyzed, and significance of both laboratory & field parameters. During the third
<br /> quarter 2003 monitoring event, all samples were collected after purging three volumes of well casing.
<br /> Results
<br /> Results of field and analytical parameters collected to date to evaluate and optimize the performance of
<br /> ozone injection system are presented in Tables 4 and 5. Change in DO concentrations for select
<br /> observation and background monitoring wells are presented in Figure 4. The historical TPHG, benzene,
<br /> and MTBE concentration variation over time at select monitoring wells (MW-4 through MW-8) are
<br /> illustrated graphically in Figures 5 through 9. Figure 10 presents the concentrations of TPHG, benzene,
<br /> and MTBE in all monitoring wells detected during the third quarter 2003 groundwater monitoring event.
<br /> MTBE concentrations in MW-6 had decreased by 10,000 µg/L in comparison to second quarter 2003.
<br /> Benzene concentrations had decreased in monitoring wells MW-4 and MW-8. Benzene and MTBE
<br /> concentrations had increased in off-site monitoring well MW-10 in comparison to the concentrations
<br /> observed during the second quarter 2003. TPHG was reported in wells MW-4, MW-5, MW-6, MW-8, and
<br /> MW-10, at concentrations ranging from 310µg/l_to 9,300µg/L. The laboratory noted that in each sample,
<br /> the reported TPHG concentrations were due to a discrete peak at C5 and on this basis, these results have
<br /> been rejected. During third quarter 2003, the highest benzene and MTBE concentrations reported were
<br /> 1,700 pg/L (MW-4) and 49,000 µg/L (MW-6), respectively. Petroleum hydrocarbons and BTEX
<br /> constituents were not reported in groundwater samples collected from MW-1 through MW-3 or MW-9.
<br /> MTBE was also reported in groundwater samples collected from MW-1 through MW-3, MW-9, and
<br /> MW-10 and the concentrations were generally lower in comparison to second quarter concentrations
<br /> except in monitoring wells MW-9 and MW-10. 1,2-DCA was reported in groundwater samples collected
<br /> PABA-Arco for URS\54691Quarterly120031Arco_5469_3QO3.doc 5 rRATU5
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