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inorganic constituents exhibited an increasing trend according to the Mann-Kendall/ Sen's Slope
<br /> analysis: barium AMW-6 and AMW-14, bicarbonate alkalinity at AMW-2, AMW-6, AMW-7,
<br /> and AMW-13, calcium at AMW-7 and AMW-14, chloride at AMW-6 and AMW-7, hexavalent
<br /> chromium at AMW-14, magnesium at AMW-6, AMW-7, and AMW-14, nitrate at AMW-2,
<br /> AMW-6, AMW-7, and AMW-14, potassium at AMW-14, sodium at AMW-14, field specific
<br /> conductance at AMW-2 and AMW-7, strontium at AMW-6 and AMW-14, sulfate at AMW-7,
<br /> and TDS at AMW-6 and AMW-7. Carbonate at AMW-2 exhibited an apparent increasing trend
<br /> according to the Mann-Kendall/ Sen's Slope analysis,but this trend is due to a historical increase
<br /> in the laboratory RL.
<br /> There was only one constituent that exhibited a statistically significant increasing trend during the
<br /> third quarter 2010 and also exceeded a concentration limit: barium at AMW-14. As described
<br /> above, the third quarter 2010 barium concentration at AMW-14 (0.263 mg/L) is comparable to
<br /> historical concentrations observed at that well, and is well below the National Primary Drinking
<br /> Water Standard(2 mg/L).
<br /> Mann-Kendall / Sen's Slope analysis identified decreasing trends in the following inorganic
<br /> parameters: barium at AMW-12, calcium at AMW-12, chloride at AMW-12, magnesium at
<br /> AMW-12, nitrate at AMW-13, field pH at AMW-2, potassium at AMW-7 and AMW-12,
<br /> strontium at AMW-12, and field turbidity at AMW-2 and AMW-14.
<br /> None of the VOCs that were detected in detection monitoring wells during the third quarter 2010
<br /> monitoring event exhibited a significant increasing trend according to the Mann-Kendall / Sen's
<br /> Slope analysis. Mann-Kendall/ Sen's Slope analysis identified decreasing trends in the following
<br /> VOCs that were detected in a detection monitoring well during the third quarter 2010:
<br /> tetrachloroethene and trichloroethene at AMW-14.
<br /> 2.2 Corrective Action Monitoring
<br /> During the third quarter 2010 monitoring event, Del-Tech collected groundwater samples from
<br /> corrective action monitoring wells (AMW-1, AMW-5R, AMW-10, AMW-11, AMW-18, AMW-
<br /> 19, and AMW-19BR). Corrective action monitoring well AMW-5R is a replacement for
<br /> corrective action monitoring well AMW-5. Corrective action monitoring well AMW-19BR is a
<br /> replacement for corrective action monitoring well AMW-19B. The field results provided by Del-
<br /> Tech and laboratory results provided by TestAmerica for the third quarter 2010 corrective action
<br /> monitoring event are summarized on Table 2.3. The historical groundwater data for the
<br /> corrective action monitoring wells are presented in Appendix F. Times series concentration plots
<br /> of historical groundwater data for the detection monitoring wells are presented in Appendix G.
<br /> For VOCs, only those compounds that exhibited detections at corrective action monitoring wells
<br /> during the third quarter 2010 monitoring event were plotted.
<br /> VOCs have been consistently detected in samples from corrective action monitoring wells AMW-
<br /> 1,AMW-4, AMW-10, and AMW-11. Wells AMW-5/5R, AMW-18, AMW-19, and AMW-19BR
<br /> have previously exhibited sporadic VOC detections.
<br /> Historical data from the corrective action monitoring wells from March 1994 to the present were
<br /> analyzed for temporal trends using Mann-Kendall / Sen's Slope trend analysis. Graphs and
<br /> summary tables of the Sen's Slope analyses for corrective action monitoring wells are presented
<br /> in Appendix G. Table 2.4 summarizes the results of the corrective action monitoring well trend
<br /> analysis. The following inorganic constituents exhibited an increasing trend according to the
<br /> Mann-Kendall/ Sen's Slope analysis: barium at AMW-1 and AMW-5R, bicarbonate at AMW-1,
<br /> 3
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