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09'August 2000" :. AGE-NC Project-No. 95-0106 Page 7 of 10 ; and. 8:5 gg/1 toluene, and 27 µg/l,and 67 jag/l ethylbenzene and 60.9g/1 and 64 ktg/1 xylenes,in samples from MW-1 and MW-4; respectively. Other analytes were not detected in the two samples. Neither TPH-g nor BTEX compounds were detected in theground water samples from monitoring- wells-MW-2,MW-3,MW-5,MW-6(upper)or MW-6(lower).and MW-7. Oxygenated fuel additives were not detected in any of the ground water samples by EPA Method 8260M.'Analytical results of ground water samples are summarized-an Tables 2, and 3. The laboratory report (MAI Laboratory ID 31680 through 31687), QA/QC and chain-of-custody are included in Appendix B. 5.4. SUMMARY AND CONCLUSIONS The following conclusions were drawn from-the results of the site investigation: . • The ground water was generally northward on 24 February,2000, and was calculated'to range from 0.006 toward the north-northwest to 0.005 toward the north-northeast. • Ground water elevation at the site increased an average of 1.44 feet since the last.quarterly monitoring event.. Dissolved petroleum hydrocarbons were detected in ground water samples from monitoring wells MW-I and MW-4, located cross to down-gradient on-site and down-gradient off-site, respectively, from the former UST excavation. . • Oxygenated compounds were not detected in.any of the ground water samples by EPA Method 8260-Modified, and have not been,detected in samples from-the site in'the past by- EPA Method,8260-Modified. BTEX compounds were detected in the water samples collected from MW-1 and MW-4, the concentrations of benzene in"both samples exceeded the State of California maximum contaminant level (MCL) of 1 µg/1 for drinking.water. a. As can be ween on Table 2; the concentrations of analytes detected in the ground water samples from the impacted-on-site monitorin well W-1 have generally declined over the . _ g � . ) g Y _ course of the six previous;sampling/monitoiing'events, but have rebounded during the four'. quarters of 1999 and first quarter of 2000. • Analytical data from monitoring well MW-2 limits the extent of dissolved hydrocarbons southward of the site. Analytical data from well MW-Sand MW-6 limits the extent of dissolved hydrocarbons northeastward of the site. Analytical data from monitoring well MW-5 limits the extent of dissolved hydrocarbons north-westward of the site.Analytical data from'well MW-Tlimits'the extent of dissolved hydrocarbons east of the site. ' Advanced GeoEnvironmentai,Inc.