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l KLE/NFELDER <br /> \\ e.. N iPle. xen,:owc� <br /> The concentrations of nitrate as N in the shallow groundwater monitoring well MW-5 exceeded <br /> the California Maximum Contaminant Level (MCL) of 10 mg/I in drinking water as expressed in <br /> Section 64431 of Title 22 of the California Code of Regulations §64431 22CCR. The MCL for <br /> nitrate as N concentrations were also exceeded in 11 of the 12 samples collected from the <br /> dewatering discharge during the fourth quarter. The results are shown in Table 8. <br /> For a summary of the results previously obtained , please refer to Table 8 under the "Tables" <br /> tab of this report. A comparison of the concentrations of the water samples obtained from the <br /> monitoring wells is shown in Chart 8 , also under the "Tables' tab of this report. <br /> Past data show that the nitrate concentrations in much of the shallow perched monitoring well <br /> samples were in excess of the State of California Maximum Contaminant Level [MCL] for <br /> nitrate-nitrogen . <br /> Based on Kleinfelder's "Report Submittal , Additional Subsurface Investigation , Norman's <br /> Nursery," dated December 31 , 1998 , it appears that the shallow perched water is not <br /> continuous between MW-2 and MW-5. Therefore, it is not technically appropriate to conclude <br /> that the nursery has raised the concentration in the perched aquifer as it passed beneath the <br /> nursery. Rather, due to the apparently low-permeability silts and clays present, the sporadic <br /> occurrence of the perched groundwater may suggest multiple areas of perched groundwater <br /> conditions. This is also consistent with an alluvial and overbank depositional environment. <br /> Therefore, channel deposits would be sporadic in their occurrence and generally be within <br /> finer grained overbank sediments. Additionally, the reason for high concentrations of nitrate <br /> above the MCL upslope (east) of the nursery is unknown , but may be indicative of other <br /> sources of nitrates in shallow groundwater or regional groundwater quality problems. <br /> 5. 1 . 3 Deep " Main" Aquifer <br /> Depth-to-water in the three deep monitoring wells during the fourth quarter monitoring event <br /> ranged from 146 . 85 (DP-2) to 159 . 00 (DP- 1 ) feet below the tops of the monitoring well <br /> casings. The groundwater elevations ranged from - 18 .20 (DP-3 ) to -17. 75 (DP-1 ) feet msl . <br /> The results are shown in Table 7 . <br /> 117226. E02/ST013R0176 Page 23 of 40 January 31 , 2013 <br /> Copyright 2013 Kleinfelder <br />