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KLEINFELDER MTBE was detected in MW-DIS-14s with a concentration of 0.64 µg/1. The Primary Maximum Contaminant Level (PMCL) for MTBE is 13 µg/1 and the Secondary Maximum Contaminant Level (SMCL) for MTBE is 5 µg/1. The detected concentration of MTBE in MW-DIS-14s does not exceed the PMCL or the SMCL for MTBE this quarter. There were no detectable concentrations at or above the laboratory reporting limit for the oxygenates MTBE, DIPE, ETBE, and TAME in the groundwater sample collected from MW-DIS-15 this quarter. PMCLs are derived 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 }Lg/l. This marks the first time TBA has been detected in MW-DIS-1 ls. The supplemental groundwater samples collected from MW-DIS-11s, MW-DIS-11d, MW-DIS- 14s, and MW-DIS-14d on September 3, 2003 (prion 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-11s with a concentration of 370 µg/l and ND results of ferrous iron. The j total iron concentration was therefore 370 µg/l. 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/l with no ferrous iron detected and a subsequent total iron concentration of 1,100 µg11. The Redox potential in MW-DIS-14s was 520 mV. There were no detected iron components (ferric or ferrous) detected in MW-DIS 11 d or MW-DIS- 14d. The Redox potentials were 510 mV and 520 mV, respectively On September 9 and 10, 2003, dissolved ozone and ozone gas were field measured from MW- DS-11s and MW-DIS-14s. Again, on October 7, 2003, dissolved ozone was measured in MW- DIS-11d 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. The supplemental groundwater samples, collected from MW-DIS-lls and MW-DIS-14s on September 9, 2003 and October 7, 2003, following the start up 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 µg/l to 38 µg/1, and from 4.4 µg/l to 2.0 µg/1 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-11s and MW-DIS-14s, although a slight increase in MTBE was noted (0.65 µg11) back to its July 30, 2003 level of 0.64 µg11. Kleinfelder recommends that a copy of this report be submitted to Mr. Mike InfiuTra of the San Joaquin County Public Health Services Department Environmental Health Division (PHS/EHD) and Mr. Marty Hartzell of the Central Valley Office of the State of California Regional Water Quality Control Board (CVRWQCB) by Del Monte Foods for their review and consideration. fThis report is subject to the limitations found in Chapter 7 of this report. 12280.MON/ST03R1392 Page 2 of 14 2003,Kleinfelder,Inc October 13,2003