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18, AMW-19, and AMW-19BR, TDS at AMW-4 and AMW-11, field temperature at AMW-4
<br />and AMW-11, and field turbidity at AMW-1 and AMW-18. Carbonate at AMW-18 exhibited an
<br />apparent increasing trend according to the Sen's Slope analysis, but this trend is due to a
<br />historical increase in the laboratory RL.
<br />The field pH value observed at AMW-1 during the fourth quarter 2009 (6.58 s.u.) is comparable
<br />to historical pH values observed at that well, and is within the National Secondary Drinking
<br />Water Standard range (6.5 - 8.5 s.u.). The field pH value observed at AMW-18 during the fourth
<br />quarter 2009 (7.10 s.u.) is comparable to historical pH values observed at that well, and is within
<br />the National Secondary Drinking Water Standard range (6.5 - 8.5 s.u.). The field pH value
<br />observed at AMW-19 during the fourth quarter 2009 (7.04 s.u.) is comparable to historical pH
<br />values observed at that well since November 2007, and is within the National Secondary
<br />Drinking Water Standard range (6.5 - 8.5 s.u.).
<br />The following VOCs exhibited an increasing trend according to the Sen's Slope analysis: 1,1-
<br />dichloroethane at AMW-1 and AMW-19BR, cis-l,2-dichloroethene at AMW-1, AMW-10, and
<br />AMW-1913R, tetrachloroethene at AMW-19, and trichloroethene at AMW-19 and AMW-1913R.
<br />Acetone at AMW-5 and AMW-10 exhibited an apparent increasing trend according to the Sen's
<br />Slope analysis, but this trend is due to a historical increase in the laboratory RL.
<br />The fourth quarter 2009 concentration of 1,1-dichloroethane at AMW-1 (2.1 ug/L) is comparable
<br />to historical concentrations observed at that well. The fourth quarter 2009 concentration of 1,1-
<br />dichloroethane at AMW-19BR (0.64 ug/L) is comparable to concentrations observed at that well
<br />for the past four monitoring events. The fourth quarter 2009 concentration of cis-1,2-
<br />dichloroethene at AMW-1 (1.4 ug/L) is comparable to historical concentrations observed at that
<br />well intermittently since October 2001, and is well below the National Primary Drinking Water
<br />Standard (70 ug/L). The fourth quarter 2009 concentration of cis-1,2-dichloroethene at AMW-10
<br />(0.32 ug/L) is comparable to historical concentrations observed at that well, and is well below the
<br />National Primary Drinking Water Standard (70 ug/L). The fourth quarter 2009 concentration of
<br />cis-1,2-dichloroethene at AMW-19BR (1.0 ug/L) is comparable to concentrations observed at that
<br />well for the past four monitoring events, and is well below the National Primary Drinking Water
<br />Standard (70 ug/L).
<br />The fourth quarter 2009 concentration of tetrachloroethene at AMW-19 (1.8 ug/L) is comparable
<br />to concentrations observed at that well since November 2006, and is below the National Primary
<br />Drinking Water Standard (5 ug/L). The fourth quarter 2009 concentration of trichloroethene at
<br />AMW-19 (0.81 ug/L) is comparable to concentrations observed at that well since November
<br />2006, and is below the National Primary Drinking Water Standard (5 ug/L). The fourth quarter
<br />2009 concentration of trichloroethene at AMW-19BR (5.2 ug/L) is comparable to concentrations
<br />observed at the well for the past four monitoring events, and is slightly above the National
<br />Primary Drinking Water Standard (5 ug/L).
<br />Sen's Slope analysis identified decreasing trends in the following VOCs: 1,1-
<br />dichlorochloroethane at AMW-10, chloroform at AMW-19BR, cis-1,2-dichloroethene at AMW4
<br />and AMW-11, dichlorofluoromethane at AMW-1, AMW-10, and AMW-11, tetrachloroethene at
<br />AMW-4, AMW-10, and AMW-11, trichloroethene at AMW-4 and AMW-11, and vinyl chloride
<br />at AMW-4. The following organic constituents exhibited an apparent decreasing trend according
<br />to the Sen's Slope analysis, but this trend is due to a historical decrease in the laboratory RL: 1,1-
<br />dichloroethane at AMW-4, 1,4 -dichlorobenzene at AMW-1 and AMW-4, benzene at AMW-1 and
<br />AMW-4, chloroform at AMW4 and AMW-11, chloromethane at AMW-4,
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