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range of concentrations observed at AMW-13 since August 2003 (0.15 to 15 ug/L). As discussed
<br /> above,trichloroethene at AMW-13 does not exhibit a significant increasing statistical trend.
<br /> 2.2 Corrective Action Monitoring
<br /> During the first quarter 2011 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 first quarter 2011 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 first quarter 2011 monitoring event were plotted.
<br /> During the first quarter 2011, there were no VOCs detected above the laboratory RL in wells
<br /> AMW-4, AMW-5R, AMW-10, AMW-11, or AMW-18. 1,4-Dichlorobenzene, chlorobenzene,
<br /> cis-1,2-dichlorobenzene, and vinyl chloride were detected at AMW-1 above the laboratory RL.
<br /> Tetrachloroethene and trichloroethene were detected at AMW-19 above the laboratory RL.
<br /> Dichlorodifluoromethane, tetrachloroethene, and trichloroethene were detected at AMW-19BR
<br /> above the laboratory RL.
<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 Mann-Kendall / Sen's Slope analyses for corrective action monitoring
<br /> wells are presented in Appendix G.
<br /> Table 2.4 summarizes the results of the corrective action monitoring well trend analysis. Mann-
<br /> Kendall / Sen's Slope analysis identified significant increasing statistical trends in the following
<br /> inorganic constituents: arsenic at AMW-19BR, barium at AMW-1, bicarbonate at AMW-1 and
<br /> AMW-5R, chloride at AMW-5R, nitrate at AMW-4 and AMW-5R, field pH at AMW-4, AMW-
<br /> 5R, AMW-11, and AMW-19BR, potassium at AMW-5R, sodium at AMW-5R, field specific
<br /> conductance at AMW-1 and AMW-5R, sulfate at AMW-5R and AMW-10, TDS at AMW-5R,
<br /> and field turbidity at AMW-5R and AMW-10. Carbonate at AMW-1 and AMW-5R exhibited an
<br /> apparent increasing trend according to the Mann-Kendall / Sen's Slope analysis, but this trend
<br /> due to a historical increase in the laboratory RL.
<br /> Mann-Kendall / Sen's Slope analysis identified significant decreasing statistical trends in the
<br /> following inorganic constituents: barium at AMW-4, AMW-10, and AMW-11, bicarbonate at
<br /> AMW-4, AMW-10, and AMW-11, calcium at AMW-4, AMW-10 and AMW-11, chloride at
<br /> AMW-4, AMW-10, AMW-11, and AMW-18, gasoline-range hydrocarbons at AMW-4,
<br /> magnesium at AMW-4, AMW-10, and AMW-11, nitrate at AMW-1, AMW-10, AMW-18,
<br /> AMW-19, and AMW-19BR, field pH at AMW-1, potassium at AMW-4, AMW-10, AMW-11,
<br /> AMW-18, and AMW-19BR, sodium at AMW-4, AMW-10, AMW-18, AMW-19, and AMW-
<br /> 1913R, field specific conductance at AMW-4, and AMW-11, strontium at AMW-4 and AMW-10,
<br /> sulfate at AMW-1 and AMW-19, field temperature at AMW-4 and AMW-11, TDS at AMW-4,
<br /> AMW-10, AMW-11, AMW-18, and AMW-19, and field turbidity at AMW-1, AMW-4, and
<br /> AMW-18.
<br /> 4
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