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• maintenance of the ozone injection system Field data sheets presenting field parameters collected during
<br /> the second quarter 2005 are included in Appendix A Certified analytical reports with chain-of-custody
<br /> documentation are included in Appendix C Analytical data were submitted to the State Water Resources
<br /> Control Board as required by AB2886 The electronic delivery receipt is attached in Appendix C
<br /> Ozone Infection Monitoring Plan
<br /> Monitoring wells MW-3 through MW-10 are used as observation wells to monitor the performance of the
<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 the groundwater
<br /> During the second quarter 2005, field parameters were collected on a monthly basis and select laboratory
<br /> parameters were collected on a quarterly basis During the second quarter 2005 monitoring event, all
<br /> samples were collected after purging three volumes of well casing The modified ozone injection
<br /> monitoring plan is listed below and a summary of frequency and significance of field and laboratory
<br /> parameters is presented in Table 3
<br /> Field Parameters(Monthly) pH, Dissolved Oxygen (DO), and Specific Conductivity
<br /> Laboratory Parameters (Quarterly) GRO, BTEX, five oxygenates, 1,2-DCA, EDB, ethanol, Chemical
<br /> Oxygen Demand (COD), Total Iron, and Heterotrophic Plate Count
<br /> Laboratory Parameters (Annually) Total Organic Carbon (TOC), Nitrates, Sulfates, Orthophosphates, and
<br /> Total Dissolved Solids (TDS)
<br /> Results
<br /> Results of field and analytical parameters collected to date to evaluate and optimize the performance of
<br /> the ozone injection system are presented in Tables 4 and 5 The GRO, benzene, and MTBE
<br /> concentrations reported in all the groundwater monitoring wells during the second quarter 2005 are
<br /> presented in Figure 4 Change in DO concentrations for select observation and background monitoring
<br /> wells are presented in Figure 5 The historical GRO, benzene, MTBE, and depth to water concentration
<br /> variation over time at select monitoring wells (MW-4 through MW-8) are illustrated graphically in Figures 6
<br /> through 10
<br /> During the second quarter 2005, GRO concentrations were reported below laboratory reporting limits in all
<br /> monitoring wells since the previous monitoring event (March 16, 2005) The greatest decrease in GRO
<br /> concentrations were reported in well MW-8 (from 27,000 pg/L to less than 25,000 µg/L)
<br /> During the second quarter 2005, benzene concentrations were reported below laboratory detection limits
<br /> in all wells except for MW-4 (30 µg/L) The greatest decrease in benzene concentrations were reported in
<br /> well MW-8 (from 600 gg/L to less than 250 µg/L), since the previous sampling event(March 16, 2005)
<br /> During the second quarter 2005, MTBE concentrations appear to have decreased in wells MW-1, MW-3,
<br /> MW-4, MW-5, MW-8, MW-9, and MW-10, while concentrations appear to have increased in well MW-6
<br /> The greatest decrease in MTBE concentrations (from 23,000 pg/L to 18,000 µg/L) were reported in well
<br /> MW-8, while the increase in MTBE concentrations (from 1,500 gg/L to 18,000 µg/L) were reported in well
<br /> MW-6 MTBE was not reported in wells MW-2, MW-7, and MW-9
<br /> DIPE (1 3 µg/L) was reported in well MW-10 1,2-DCA was reported in wells MW-7 (1 3 µg/L), MW-9 (1 6
<br /> µg/L), and MW-10 (4 7 pg/L) GRO, TBA, ETBE, TAME, EDB, or ethanol were not reported in any of the
<br /> wells The petroleum hydrocarbon concentrations generally appear to have decreased since the operation
<br /> • of ozone injection Analytical data were submitted to the State Water Resources Control Board as
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