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2,2 Corrective Action Monitoring 0
<br />During the second 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 BC Labs for the second 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 second quarter 2011 monitoring event were plotted.
<br />During the second quarter 2011, there were no VOCs detected above the laboratory RL in wells
<br />AMW-4, AMW-5R, AMW-11, or AMW-18. 1,1-Dichloroethane, 1,4 -dichlorobenzene, benzene,
<br />chlorobenzene, cis -1,2 -dichlorobenzene, diisopropyl ether, tetracholorethene, and trichloroethene
<br />were detected at AMW-1 above the laboratory RL. cis-1,2-Dichloroethene and tetrachloroethene
<br />were detected at AMW-10 above the laboratory RL. Tetrachioroethene and trichloroethene were
<br />detected at AMW-19 above the laboratory RL. 1,1-Dichloroethane, cis-l,2-dichloroethene,
<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-10, barium at AMW-1, bicarbonate alkalinity at AMW-1
<br />and AMW-5R, chloride at AMW-5R, nitrate at AMW-4 and AMW-5R, field pH at AMW-4,
<br />AMW-5R, AMW-11, and AMW-19BR, potassium at AMW-5R, sodium at AMW-5R, field
<br />specific conductance at W-1 and AMW-5R, sulfate at AMW-5R and AMW-10, TDS at
<br />AMW-5R, and field turbidity at AMW-5R and AMW-10. Carbonate at AMW-5R exhibited an
<br />apparent increasing trend according to the Mann -Kendall / Sen's Slope analysis, but this trend is
<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
<br />alkalinity at AMW-4, AM -10, and AMW-11, calcium at AMW-4, AMW-10 and AMW-11,
<br />chloride at AMW-1, AMW-4, AMW-10, AMW-11, and AMW-18, gasoline -range hydrocarbons
<br />at AMW-4, magnesium at AMW-4, AMW-10, and AMW-11, nitrate at AMW-1, AMW-10,
<br />AMW-18, AMW-19, and AMW-19BR, field pH at AMW-1, potassium at AMW-4, AMW-10,
<br />AMW-11, AMW-18, and AMW-19BR, sodium at AMW-10, AMW-18, AMW-19, and AMW-
<br />1913R, field specific conductance at AMW4, and AMW-11, strontium at AMW-4 and AMW-10,
<br />sulfate at AMW-1, AMW-19, and AMW-19BR, field temperature at AMW-4 and AMW-11, TDS
<br />at AMW-4, AMW-10, AMW-11, and AMW-18, and field turbidity at AMW-1 and AMW-4.
<br />Mann -Kendall / Sen's Slope analysis identified significant increasing statistical trends in the
<br />following VOCs: 1,1-diehloroethane at AMW-1; chlorobenzene at AMW-1; cis-1,2-
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