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Ms. Lagorio Page 2 January 12, 1995 BAE31604.AS.T8 75 feet below ground surface within fine sandy silts, clayey silts and sand. Groundwater was observed to flow northwesterly at a gradient between 0.0005 and 0.0013. As reported in the RI/FS, benzene was found to exceed the hazardous waste Toxicity Characteristic Leaching Procedure (TCLP) level for benzene of 500 µg11 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. The purpose of the AS/SVE system is to significantly reduce further dilution of petroleum hydrocarbon into the groundwater. GROUNDWATER MONITORING/QUALITY The quarterly monitoring event conducted on October 27, 1994 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-71). Monitoring well locations and a groundwater elevation contour are shown on Figure 1: Groundwater flow is inconclusive. The small groundwater elevation differences between all the monitoring wells indicates a shallow gradient. Since the previous quarter, ground water elevations for wells MW-DIS-1, -2, and -3 decreased in the range of 0.10 to 0.25 feet; wells MW-DIS-4, -5, -6, -7S, and -7D increased from 0.14 to 0.52 feet. Historical groundwater elevation data is summarized on Table 1. Monitoring wells MW-DIS-3, -4, -6, -7S, and -71) were sampled as part of the quarterly groundwater quality monitoring program. Monitoring well purge and sampling data are attached. The groundwater samples were analyzed by Quality Analytical Laboratory, Redding CA, for total petroleum hydrocarbons (TPH CA LUFT Manual/88) as gasoline; and benzene, toluene, ethylbenzene, and xylenes (BTEX) (EPA method 801518020). Results of the October 27, 1994 sampling event and results from previous sampling events are summarized in Table 2. Field data and the laboratory report are attached. The analytical results indicate that wells sampled this quarter are below the detection limits for TPH and BTEX.