ARCHIVED REPORTS_2011_12 - Laserfiche WebLink

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Mann-Kendall / Sen's Slope analysis identified significant decreasing statistical trends in the following VOCs: cis-1,2-dichloroethene at AMW-1 and AMW-10; dichlorodifluoromethane at AMW-19BR; tetrachloroethene at AMW-19; trichloroethene at AMW-1 and AMW-19; and vinyl chloride at AMW-1. Mann-Kendall / Sen's Slope analysis identified significant decreasing statistical trends in the following VOCs: 1,4-dichlorobenzene at AMW-4; benzene at AMW-4; cis-1,2-dichloroethene at AMW-4 and AMW-11; dichlorodifluoromethane at AMW-1, AMW-4, AMW-10, and AMW-11; tetrachloroethene at AMW-4, AMW-10, and AMW-11; trichloroethene at AMW-4, AMW-10, and AMW-11; and vinyl chloride at AMW-4. Arsenic was not detected at AMW-19BR during the first quarter 2011. The increasing trend for arsenic at AMW-19BR is not observed when the data are limited to the period of February 2008 to March 2011, indicating that concentrations for this constituent have stabilized in the past three years. The first quarter 2011 concentration of barium at AMW-1 (0.358 mg/L) is below the National Primary Drinking Water Standard of 2 mg/L. The increasing trend for dissolved barium at AMW-1 is not observed when the data are limited to the period of May 2005 to March 2011, indicating that concentrations for this constituent have stabilized in the past six years. The increasing trend for bicarbonate at AMW-1 is not observed when the data are limited to the period of September 1994 to March 2011, indicating that concentrations for this constituent have stabilized in the past seventeen years. The increasing trend for bicarbonate at AMW-5R is not observed when the data are limited to the period of April 1995 to March 2011, indicating that concentrations for this constituent have stabilized in the past sixteen years. The first quarter 2011 concentration of chloride at AMW-5R (69.6 mg/L) is the lowest concentration observed at that well since May 2001, and is below the National Secondary Drinking Water Standard of 250 mg/L. The increasing trend for chloride at AMW-5R is not observed when the data are limited to the period of November 2000 to March 2011, indicating that concentrations for this constituent have stabilized in the past eleven years. The first quarter 2011 concentration of nitrate at AMW-4 (0.75 mg/L) is below the National Primary Drinking Water Standard of 10 mg/L. The increasing trend for nitrate at AMW-4 is not observed when the data are limited to the period of April 2002 to March 2011, indicating that concentrations for this constituent have stabilized in the past nine years. The first quarter 2011 concentration of nitrate at AMW-4 (15.1 mg/L) is above the National Primary Drinking Water Standard of 10 mg/L. However, the increasing trend for nitrate at AMW-4 is not observed when the data are limited to the period of May 2004 to March 2011, indicating that concentrations for this constituent have stabilized in the past seven years. The first quarter 2011 field pH values at AMW-1 (6.92 s.u.), AMW-4 (8.06 s.u.),AMW-5R(7.72 s.u.), AMW-11 (7.84 s.u.), and AMW-19BR (7.85 s.u.) are within the National Secondary Drinking Water Standard range of 6.5 to 8.5 s.u. The decreasing trend for field pH at AMW-1 is not observed when the data are limited to the period of March 1996 to March 2011, indicating that pH values have stabilized in the past fifteen years. The increasing trend for field pH at AMW-4 is not observed when the data are limited to the period of August 2003 to March 2011, indicating that pH values have stabilized in the past eight years. The increasing trend for field pH at AMW-5R is not observed when the data are limited to the period of July 1998 to March 2011, indicating that pH values have stabilized in the past thirteen years. The increasing trend for field 5