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' KLEiNFELDER from health based criteria, whereas SMCLs are derived from human welfare considerations such as taste and odor. TBA was detected in MW-DIS-11s with a concentration of 11 µg11. This marks the first time TBA has been detected in MW- DIS-11s and may be a direct result of the air/ozone.sparging directed in this area. 3. The supplemental groundwater samples collected from MW-DIS-11s, MW-DIS- 1 ld, MW-DIS-14s, and MW-DIS-14d on September 3, 2003 (prior to the start-up of the ozone system), were analyzed for total iron, ferrous.iron, ferric iron, and Redox potential. The results showed only ferric iron in MW-DIS-1 is with a concentration of 370 µg/1 and ND results of ferrous iron. The total iron concentration was therefore 370 µg11. The Redox potential in MW-DIS-11s was 500 mV. Similarly, only ferric iron was detected in MW-DIS-14s with a concentration of 1,100 µg/1 with no ferrous iron detected and a subsequent total iron concentration of 1,100 µgll. The Redox potential in MW-DIS-14s was 520 mV. There were no detected iron components (ferric or ferrous) detected in MW-DIS I 1 d or MW-DIS-14d. The Redox potentials were 510 mV and 520 mV, respectively 4. On September 9 and 10, 2003, dissolved ozone and ozone gas were field measured from samples collected from MW-DS-1 is and MW-DIS-14s. Again, on October 7, 2003, dissolved ozone was measured in MW-DIS-lld and MW-DIS-14d. The results for dissolved ozone ranged from 0.10 ppm to 0.65 ppm and the ozone gas ranged from non-detect to 10.40 ppm. 5. The supplemental groundwater samples, collected from MW-DIS-11s and MW- DIS-14s on September 9, 2003 and October 7, 2003, following the startup of the ozone sparge system at the site, were analyzed for 1,2-DCA, TBA, and MTBE. The results on September 9, 2003, showed a decrease from the July 30 to August 1, 2003 quarterly sample dates in 1,2-DCA concentrations in both wells from 150 µg11 to 38 µg11, and from 4.4 µg/l to 2.0 µg/l respectively. Additionally, non-detectable concentrations at or above the laboratory reporting limits were.reported for TBA and MTBE in both wells. The results on October 7; 2003 showed comparable concentrations in MW-DIS-Ils and MW-DIS-14s, although a slight increase in MTBE was noted (0.65 µg/l) back to its July 30, 2003 level of 0.64 µg/1. 6. Kleinfelder recommends that monitoring of the site should be continued in accordance with the "Groundwater Monitoring Frequency Decision Tree" at this . time. 7. A copy of this report should be submitted to the San Joaquin County Environmental Health Department and the Central Valley Office of the State of California Regional Water Quality Control Board by Del Monte, Inc. for their review and consideration. This report is subject to the limitations found in Chapter 7 of this report. 12280.MON 1 ST03RI392 Page 13 of 14 2003,Kleinfelder,Inc October 13,2003