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KLEINFELDER 6 CONCLUSIONS AND RECOMMENDATIONS On March 4, 5, and 6, 2003, twelve 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 recommendations have been formulated: 1. Groundwater flow direction at the site is estimated to be towards the east/southeast at approximately 0.0046 ft./ft. This is consistent with the recent groundwater data collected at the site. 2. Based on the results of the groundwater sampling it. appears that the groundwater quality has remained relatively consistent with the past sampling events. The results showed no TPH-g benzene, toluene, ethylbenzene, xylene, EDB, TBA, DIPE, ETBE, or TAME detected in any of.the monitoring wells outside of the former service station footprint sampled this quarter.. Detected concentrations of the above listed analytes has remained consistent with past monitoring events.. 1;2-DCA was detected in eight of the twelve groundwater samples analyzed with the detected concentrations ranging from 0.57 ug/l (MW-DIS-2) to 2,100 ug/1(NPI-80'). The remaining four groundwater samples showed non-detect concentrations of.1,2- DCA at or above the laboratory reporting Iimit (ND < 0.5 ug/1). The PMCL for 1,2- DCA is 5 ug/l. The detected concentration of 1,2-DCA in MW-DIS-2 and MW-DIS- 14s did not exceed the PMCL for 1,2-DCA in groundwater. However, the concentration detected in MW-1, NP-1-70', NPI-80', and NP1-90' did exceed the PMCL for 1,2-DCA. This marks the first sampling event for MW-DIS-15. From the requested analytes, only 1,2-DCA was detected in the groundwater sample.collected from MW-DIS-15 with a concentration.of 10 ug/l. Only MW-DIS-14s and MW-DIS-15 were analyzed for the oxygenates. The groundwater sample from MW-DIS-14s has continued to be analyzed for oxygenates due to the re-occurring nature of MTBE in the well, and the groundwater sample from MW-DIS-15 due to the first time it was sampled. MTBE was only detected in the groundwater sample collected from MW-DIS-14s with a concentration of 1.4 ug/l. The PMCL for MTBE is 13 ug/l and the SMCL for MTBE is 5 ug/l. , The detected concentration of MTBE in MW-DIS-14s does not exceed the PMCL or the SMCL for MTBE in water. PMCLs are derived from health based criteria, whereas SMCLs are derived from human welfare considerations such as taste and odor. 12280.MON 1 ST03RS24 Page 10 of 12 ©2003,Kleinfelder,Inc May 6,2003