ARCHIVED REPORTS_2007_18 - Laserfiche WebLink

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results of the corrective action monitoring well trend analysis. The following inorganic constituents exhibited an increasing trend according to the Sen's Slope analysis:barium at AMW- 1 and AMW-18, bicarbonate at AMW-1 and AMW-18, field pH at AMW-11, field specific conductance at AMW-1, sulfate at AMW-10,and field turbidity at AMW-19. The second quarter 2007 concentration of barium at AMW-1 (0.34 mg/L) is comparable to concentrations observed at that well intermittently since May 2004, and is well below the National Primary Drinking Water Standard (2 mg/L). The second quarter 2007 concentration of barium at AMW-18 (0.16) is comparable to concentrations observed at that well intermittently since August 2005,and is well below the National Primary Drinking Water Standard(2 mg/L). The second quarter 2007 concentration of bicarbonate at AMW-1 (780 mg/L) is comparable to concentrations observed at that well intermittently since August 2003. The second quarter 2007 concentration of bicarbonate at AMW-18 (340 mg/L)is comparable to concentrations observed at that well consistently since November 2004. The field pH value observed at AMW-11 during the second quarter 2007 (7.26 s.u.) is the lowest pH observed at that well since May 2005, and is within the National Secondary Drinking Water Standard range (6.5 - 8.5 s.u.). The second quarter 2007 field specific conductance value at AMW-1 (1,250 umhos/cm) is comparable to values observed at that well consistently since March 2003. The second quarter 2007 concentration of sulfate at AMW-10 (58 mg/L) is comparable to concentrations observed at that well intermittently since October 2002, and is well below the National Secondary Drinking Water Standard (250 mg/L). The field turbidity value observed at AMW-19 during the second quarter 2007 (>999 NTUs) is consistent with the field turbidity observed during the past two monitoring events. Sen's Slope analysis identified decreasing trends in the following inorganic parameters: arsenic at AMW-18 and AMW-19, barium at AMW4, bicarbonate at AMW-4, calcium at AMW-4 and AMW-11, chloride at AMW-1, AMW-4, and AMW-11, magnesium at AMW-4 and AMW-11, nitrate at AMW-1, field pH at AMW-1, potassium at AMW4, sodium at AMW-18 and AMW- 19, strontium at AMW-4 and AMW-11, field specific conductance at AMW-11, sulfate at AMW- 1, AMW-18, and AMW-19, total dissolved solids (TDS) at AMW-4 and AMW-11, and field turbidity at AMW-4. The field pH value observed at AMW-1 during the second quarter 2007(6.60 s.u.) is comparable to pH values observed at that well intermittently since August 1997, and is within the National Secondary Drinking Water Standard range(6.5 -8.5). The following organic parameters exhibited an increasing trend according to the Sen's Slope analysis: cis-l,2-dichloroethene at AMW-1 and AMW-10, tetrachloroethene at AMW-19, and vinyl chloride at AMW-1. The second quarter 2007 concentration of cis-1,2-dichloroethene at AMW-1 (2.3 ug/L) is comparable to concentrations observed at that well intermittently since October 2001. The second quarter 2007 concentration of cis-l,2-dichloroethene at AMW-10(0.64 ug/L)is the lowest concentrations observed at that well since November 1999. The concentration of cis-1,2- dichloroethene at both AMW-1 and AMW-10 is below the National Primary Drinking Water Standard(70 ug/L). The second quarter 2007 concentration of tetrachloroethene at AMM-19(4.4 ug/L) is comparable to the concentration observed during the previous two monitoring events, and is below the National Primary Drinking Water Standard (5 ug/L). The second quarter 2007 concentration of vinyl chloride at AMW-1 (0.88 ug/L) is comparable to concentrations observed 4