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KLEINFELDER ' ND = Analyte not detected at or above the laboratory reporting limit. ' Chain-of-custody forms and laboratory analytical reports are included in Appendix C, attached. Table 2 is a summary of the current and historical analytical results of groundwater sampling. For a graphical representation of current and historical data for ' selected wells and analytes, please refer to Charts 2 through 6. 5.3. SEMI-ANNUAL ANALYTICAL TRENDS (PRIMARY ANALYTES) The following is a discussion of recent and historical trends noted in the distant ' upgradient well (MW-5), the adjacent/downgradient wells (MW-1/MW-1r and MW- 2/MW-2r), and the distant downgradient well (MW-6r) for EC, TDS, and bicarbonate alkalinity. ' Concentrations of each of the analytes decreased slightly in the upgradient well MW-5 in comparison to the previous semi-annual sampling event. The concentrations during ' the second semi-annual 2007 sampling event were generally consistent with previous sampling results. ' The concentration of TDS, bicarbonate alkalinity, and EC decreased in the adjacent/downgradient well MW-1r and increased in the adjacent/downgradient well MW-2r since the last monitoring event. The concentrations of TDS and bicarbonate ' alkalinity, and EC values continue to exhibit a generally decreasing trend in both MW-1 r and MW-2r. ' Concentrations of TDS, bicarbonate alkalinity, and EC values increased in the distant downgradient well MW-6r compared to the previous sampling event. The concentrations of each of the analytes exhibit an overall decreasing trend in MW-6r ' since at least 2001. Overall, the concentrations of EC, TDS, and bicarbonate alkalinity have been ' decreasing since at least the July 2000 sampling event in the adjacent/downgradient wells MW-1r, MW-2r, and the distant downgradient well, MW-6r. In addition the concentrations of EC, TDS, and bicarbonate alkalinity have reached levels significantly ' below those of the initial sampling events for each of those wells (November 1992 for MW-1/1r and MW-2/2r and July 1997 for MW-6/6r) and below the highest historical concentrations in the upgradient well MW-5. The trend of decreasing concentrations in ' the downgradient wells is shown on the attached Charts 2 through 6. Periodic fluctuations in concentrations continue to be below the historical high concentrations noted for each of the analytes. The concentrations of TDS, bicarbonate alkalinity, and EC increased in both intermediate distant downgradient wells MW-25 and MW-27, however were generally ' consistent with previous findings, and indicated generally stable concentrations. An exception to this trend is the concentrations of bicarbonate alkalinity in MW-25, which have been generally increasing since monitoring began, yet remain below historical ' 20-3978-03.MN71STUR117 February 1,2008 0 2008 Kleinfelder Page 14 of 19