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Mr. Michael Collins Page 2 December 15, 1993 SF031604.AS As reported in the RI/FS, benzene was found to exceed the hazardous waste Toxicity Characteristic Leaching Procedure (TCLP) level for benzene of 500 ugll in Monitoring Wells MW-DIS-1 and -2. Benzene concentrations in Monitoring Wells MW-DIS-1, -2, -3, and -71) have exceeded the California Maximum Contaminant Level (MCL) for benzene of 1 µg11 Del Monte submitted a conceptual remediation plan to Michael Collins of San Joaquin County Public Health Services (PHS) on August 19, 1993. The remediation plan specifies air sparging combined with soil vapor extraction (AS/SVE) to remediate the source of gasoline constituents in the subsurface beneath the Disco Property. GROUNDWATER MONITORING/QUALITY The quarterly monitoring event conducted on September 30, 1993 consisted of water level measurements and groundwater sampling. Water level depths were measured in monitoring wells MW-DIS-1 through MW-DIS-7S and MW-DIS-713. Monitoring well locations and groundwater elevation contours are shown on Figure 1. The groundwater elevation contour- lines shown on Figure 1 indicate that groundwater is flowing in a northwesterly direction` with a shallow gradient.' Water level elevations from this quarter and previous monitoring events are summarized on Table 1. Monitoring wells MW-DIS-3, -4, -6, -7S, and -7D were sampled on September 30, 1993 as part of the quarterly groundwater quality monitoring program. Monitoring well purge and sampling data are attached. The groundwater samples were analyzed by the CH2M HILL Analytical Laboratory for total petroleum hydrocarbons (TPH) as gasoline; and benzene, toluene, ethylbenzene, and xylenes (BTEX) (EPA method 8015/8020). Results of the September 30, 1993 sampling event and results from previous sampling events are summarized on Table 2. The laboratory report is also attached. No petroleum hydrocarbons were detected in any of the monitoring wells sampled on September 30, 1993. SCHEDULE The current schedule of activities is presented on Table 3. As discussed with Michael Collins/PHS on December 6, 1993, the schedule for construction of the planned AS/SVE system has been delayed until April 1994 to provide adequate review time of the air permit by the San Joaquin Valley Unified Air Pollution Control District. Del Monte is currently preparing the air permit application and the AS/SVE construction and performance ( specifications. quartcrly.rep