ARCHIVED REPORTS_2012_2 - Laserfiche WebLink

Home Browse Search

No VOCs were reported at this well this quarter. A trace concentration of Dichlorodifluoromethane was reported in SB-1 during the 4t'Quarter 2011 sampling event. Prior to the 4h Quarter 2011 sampling event,VOCs have not been reported in this well since second quarter 2004 when trace concentrations of Dichlorodifluoromethane were reported. MW-4(Down gradient): Concentrations of all the parameters analyzed were within established concentration limits this quarter except for Bicarbonate Alkalinity(Table 1). However, because there are no primary and secondary MCLS for Bicarbonate Alkalinity,this exceedance does not pose a human health risk. One primary MCL for Nitrate as Nitrogen was slightly exceeded in MW-4 this quarter. Secondary MCLS for EC, Sulfate, and TDS were also exceeded in MW-4 this quarter. However, the Nitrate, EC, Sulfate, and TDS levels are consistent with the general historical conditions at this well. ! Sanitas statistical analysis indicates decreasing trends in Chloride, TDS, and Sulfate this quarter (Table 3). These trends were first apparent during the following quarters: ! Chloride in first quarter 2003 Sulfate in first quarter 2005 TDS in second quarter 2001 This indicates the continuation of a relatively long trend of improving general water quality conditions at this well. It is likely that the improvements to the drainage ditch in 2003 resulted in these improvements in general water quality at MW-4. No VOCs were reported at this well this quarter. Other than compounds also reported in quality control blanks, VOCs have not been reported in this well since third quarter 2001. 31'W-5(Impacted): Concentrations of all the parameters analyzed were within established concentration limits this quarter except for Bicarbonate Alkalinity(Table 1). However,because there are no primary and secondary MCLS for Bicarbonate Alkalinity,this exceedance does not pose a human health risk. Based on output from the Sanitas statistical software, increasing trends are reported in pH,EC and TDS, whereas decreasing trends are reported in the concentration of Turbidity, Bicarbonate Alkalinity and Sulfate (Table 3). One primary MCL for Nitrate as Nitrogen was slightly exceeded in MW-5 this quarter. Secondary MCLs for EC, and TDS were also exceeded in MW- 5 this quarter. However, the Nitrate, EC, and TDS levels are consistent with the general historical conditions at this well. Ten VOCs were reported in impacted well MW-5: five above "trace" concentrations and one (Tetrachloroethene) above their MCLs (Table 1). Trend analysis of VOC concentrations indicates increasing trends for Cis-1,2-Dichloroethene and Tetrachloroethene, and a decreasing trend for 1,2-Dichloropropane, Trichloroethene, and Corral Hollow Sanitary Landfill 10 Department of Public Works/Solid Waste 19`Quarter 2012 Groundwater Monitoring County of San Joaquin—April 16,2012