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k%j KLEIN FELDER 6 CONCLUSIONS AND RECOMMENDATIONS On February 21, 2002, 17 monitoring wells were sounded for depth to groundwater. The 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 southeast at approximately 0.0005 ft./ft. This is consistent with the historical groundwater data collected at the site. 2. Based on the results of the groundwater sampling it appears that the groundwater quality has remained consistent with' past sampling events, showing fluctuating elevated concentrations of TPH-g near the source area of the plume and diminishing { with distance downgradient of the plume. The reported concentration of TPH-g has I risen in MW-DIS-1, and dropped in all of the other previously monitored wells included in this monitoring event compared to the last monitoring event in October, 2001. Monitoring wells MW-DIS-lls, MW-DIS-11d, MW-DIS-12, MW-DIS-13, MW-DIS-14, and MW-DIS-14d were sampled for the first time this quarter. The results show a concentration of TPH-g in MW-DIS-11s of 64 mg/l. No TPH-g was detected in the other monitoring wells sampled for the first time this quarter. Similarly, but to a lesser extent, the concentrations of 1,2-DCA, EDB are shown to be elevated'}near the source area and also diminish with distance from the source to non-detect concentrations at the furthest downgradient monitoring well (MW-DIS- 1-2). . The concentration of 1,2-DCA was shown to decrease in MW-DIS-1, and NP- 1-90', rise in SVE-north and NP-1-70', and remain steady in SVE-south and NP-1- i 80' compared to the October 2001 sampling. The concentrations of EDB detected in the groundwater samples all showed decreases in concentration or remained steady 4 compared to the October 2001 results. No detectable concentrations of 1,2-DCA or EDB were found in MW-DIS-1ld, MW-DIS-12, MW-DIS-13, and MW-DIS-14d. . The detected concentrations of 1,2-DCA and EBD exceed their PMCL for in each of the monitoringwells where 1,2-DCA and EDB was detected. The concentration of benzene was shown to increase in each of the monitoring wells sampled this quarter. Benzene was detected in the newly installed monitoring well MW-DIS-11s with a concentration of 0.45 mg/l. The detected concentration of benzene is below the PMCL for benzene in water in monitoring well MW-DIS-2. The remaining seven detected concentrations of benzene exceed the MCL for benzene in groundwater. 12280.MON12002R394 Page 12 of 15 ®2002,Kleinfelder,Inc May 10,2002