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KEI-P86-084C November 4, 1988 Page 2 _ Monitoring data are summarized in Table 1. Free product or sheen was noted only in MW-3. Slight to strong odor was consistently noted in MW-3, MW-4, and MW-5 during monitoring. Water samples were taken from the wells on October 13, 1988. Prior to sampling, the wells were purged of at least ten gallons water. Samples were then collected using a clean Teflon bailer, which was carefully raised from the well to minimize volatilization. Samples were decanted into clean VOA vials which were sealed with Teflon-lined screw caps and stored on ice until delivery to the contracted laboratory. LABORATORY ANALYSES The water samples were analyzed at Sequoia Analytical Laboratory in Redwood City for total petroleum hydrocarbons as gasoline (TPH) , benzene, toluene, xylene and ethylbenzene (BTX&E) concentrations using EPA method 5030, in conjunction. with modified 8015 and 8020 (Table 2) . DISCUSSION During monthly monitoring and sampling, a trace of free product and sheen was noted only in MW-3 . The latest analytical results show benzene levels ranging from non-detectable to 7000 ppb (Table- 2) . RECOMMENDATIONS 1. Conduct short term pumping test on MW-5. 2 . Excavate all soil from the southeast corner of the tank pit to Tracy Blvd. and north to Grantline Road to a depth of ten feet (Figure 1) . Properly aerate and dispose of contaminated soil. 3 . Pump all water from the pit for a period of two days. Properly dispose of all pumped water. 4. Refill excavation with clean material. 4 5. Install one on-site monitoring well to a depth of 20 feet to further define the extent of ground water contamination (Figure 2) . 6. Install two off-site monitoring wells to a depth of 20 feet to determine the extent of ground water contamination north and east of the site (Figure 2) .