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6 CONCLUSIONS AND RECOMMENDATIONS { On November 19 and 20, 2003, 7 monitoring wells were purged and sampled. Water samples obtained from each location were submitted for chemical analysis. , Based on the data obtained during our assessment, the following conclusions and 1 recommendations have been formulated: 1. Groundwater flow direction at the site is estimated to be towards the east/southeast at approximately 0.002 f1/ft. A localized groundwater mound was noted near MW- DIS-11s, MW-DIS-Ild, and 14s, whereas a localized depression was noted near MW-DIS-15. Both localized anomalies may be a direct result of the sparging activities in the area. 2. Based on the results of the groundwater sampling it appears that the groundwater duality has remained relatively consistent with the past sampling events. The results showed no TPH-g, benzene, toluene, ethylbenzene, xylene, EDB, DIPE, ETBE, or TAME detected in any of the monitoring wells outside of the former service station footprint sampled this quarter. However, this is the second time TBA has been detected in the downgradient monitoring well MW-DIS-1 Is. The concentrations of the above listed analytes has remained consistent with past monitoring events. TPH-g was not detected in any of the groundwater samples collected this quarter. Similarly, BTEX compounds were not detected in any of the groundwater samples collected this quarter. 1,2-DCA was detected in 3 of the 7 groundwater samples. The detected concentrations ranged from 1.4 µg/1 (MW-DIS-14s) to 96 µg/1 (MW-DIS-11s). The detected concentrations of 1,2-DCA exceeded the Primary Maximum Contaminant Level (PMOL) for 1,2-DCA of 5 µg11 in 2 of the samples (MW-DIS-11s and MW- DIS-15). EDB was not detected in any of the 7 groundwater samples analyzed this quarter. MTBE was only detected in MW-DIS-14s with a concentration of 0.50 gg/1 (which was just at the laboratory reporting limit). The Primary Maximum Contaminant Level (PMOL) for MTBE is 13 �Lg/l and the Secondazy Maximum Contaminant Level (SMCL) for MTBE is 5 �tg/l. The detected concentration of MTBE in MW- DIS-14s does not exceed the PMCL or the SMCL for MTBE this quarter. There were no detectable concentrations at or above the laboratory reporting limit for the oxygenates MTBE, DIPE, ETBE, and TAME in the groundwater sample collected from MW-DIS-15 this gliarter. PMCLs are derived from health based criteria, whereas SMCLs are derived from human welfare considerations such as taste and l odor. l TBA was detected in each of the 7 groundwater samples analyzed. The concentrations of TBA ranged from 8.6 µg/1 (MW-DIS-15) to 10.8 ptg/l (MW-DIS- 12280.MON/ST03R 1875 Page 11 of 13 ®2004,Kleinfelder,Inc February 9,2004 KLEINFELDER 2825 East Myrtle Street, Stockton, CA 95205-4794 (209)948-1345 (209)948-0621 fax