ARCHIVED REPORTS_2010 ANNUAL REPORT

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Nestle USA, Inc., Ripon, California March 31, 2011 2010 Annual Report • VC concentrations are present in 10 wells south of the Stockton Avenue treatment system and in the vicinity of the City of Ripon WWTP. The VC concentrations in over half of these wells are higher than the TCE concentrations in the wells (Table 3.2) indicating that intrinsic remediation via reductive dechlorination 16 is occurring. 3.3.3 LOWER AQUIFER An evaluation of COC impacts in the Lower Aquifer is provided in the following sections. TCE • Concentrations of TCE were present in six of 19 Nestle monitoring wells (Table 3.3), and ranged from 0.69 pg/L (M-20D, April)to 54 pg/L (M-61D, October). • TCE concentrations in wells M-32D and M-40D show slight increase between 2008 and 2010 (Appendix C). • Thirteen of the 19 monitoring wells sampled show stable TCE concentration trends (Appendix C). • TCE concentrations in monitoring wells M-81D and M-20D show a decreasing trend. The decreasing concentration in well M-20D is a direct effect of modification in 2009 to wells TH-8 and TH-10 which were screened across multiple aquifers (see figure below). Well M-20D Concentrations over Time Modification of TH-8 and TH-10 100 a 0 ° 000 oo 10 oo oo 0 ° 0 vJ ,° ° o00 ° O A e AA ++ i ° e AA° ° L ° 0 ° e a+ o � A > N ° o 0°° U 1 A o o a e o 0 ° V o a e o e o 0 0 004 4 4 0 0 0 a 0 0 0 0 0 0 0 000000000000A A AA 0 Mar-92 Mar-95 Mar-98 Mar-01 Mar-04 Mar-07 Mar-10 A TCE ° Cls a VC • TCE concentrations in well M-61D have been stable at approximately 50 pg/L since 2004. • The TCE concentration in well M-34D had dropped below the reporting limit in October 2006, then increased in the First Quarter 2009. Concentrations have remained steady at 2 pg/L since January 2009. 16