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I KLEINFELDER Based upon the depth of the monitoring wells, which range from 89 feet to 164 feet bgs, compared to the depths of the ozone and air sparging wells at 140 feet bgs, it appears that the surging continues to lift deeper contamination into the shallower screened zones of the monitoring wells ouring the treatment process. Though still well below their pre-remediation concentrations, the 1,2-DCA increase shown in MW-11s and MW-15 is anticipated as the lifting effect, and consequential resonation in concentrations, that is occurring at the front of the plume (downgradient of the source area) continues until the deep contamination at the source area is significantly mitigated. GROUNDWATER TREATMENT SYSTEM OPERATION The soil vapor extraction system installed by CH2M Hill was replaced by Kleinfelder during 2003 with an air sparging (AS)/high vacuum soil vapor extraction (SVE)/ozone injection system. The AS/SVE system consists of a network of two air sparging wells (shallow/deep) and a vapor extraction well positioned at five distinct locations, totaling fifteen wells. The ozone injection system consists of a horizontally directional drilled conduit.for ozone/air transmitted to a system of wells triple-nested at three different depths below groundwater, at five separate locations, equaling fifteen wells. Active remediation began in May 2003 in the source area (actual Disco site) by means of AS/SVE utilizing a thermal oxidizer unit. Continual operation of the thermal { oxidizer began in June 2003. In July 2003, the AS/SVE unit was converted from a thermal I oxidizer to catalytic oxidizer thereby optimizing the efficiency through fuel uptake. The ozone injection system began consistent operation within the downgradient portion of the plume in September 2003. The system has only been inoperable during periods of minor system maintenance and system enhancements. The most recent operational changes during the Second Quarter 2004, was the removal and installation of a new catalytic cell within the thermal/catalytic oxidizer. This was due to an overheating event of the system on April 30, 2004, which burned the previous cell. A new temperature controller was also installed on the oxidizer with a two alarm system in an attempt to ensure that future possible overheating was detected and the system is properly shut down. Air inlet sampling was also conducted at the main manifold of the catalytic oxidizer on June 2, 2004. TPH-G was detected at a concentration of 460 ppm, showing an increase from the previous (March 22, 2004) sampling event of 28 ppm, still below the 1,400 ppm detected in the September 2003 sampling event. GENERAL RECOMMENDATIONS Kleinfelder recommends that a copy re of this ort be submitted to Mr. Mike Infurna of the San p Joaquin County Public Health Services Department Environmental Health Division (EHD) and Mr. Jim Barton 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. This report is subject to the limitations found in Chapter 7 of this report. 12280.M0N/ST04R1092 Page 2 of 12 Copyright 2004 Kleinfelder,Inc. September 2,2004