ARCHIVED REPORTS_2010 ANNUAL REPORT

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Nestle USA, Inc., Ripon, California March 31, 2011 2010 Annual Report 3.3.2 INTERMEDIATE AQUIFER An evaluation of COC impacts in the Intermediate Aquifer is provided in the following sections. TCE • Concentrations of TCE were present in groundwater samples in 26 of the 37 Nestle groundwater monitoring wellsf(Table 3.2), and ranged from 0.53 pg/L (well M-5C1, April) to 220 pg/L (well TH-10, February; Table 5). • TCE concentrations in five (M-10C1, M-13A, M-21C1, M-28C1 and M-5C2) of the 37 wells shows an increasing trend. Four of the wells are located close to active or recently decommissioned City of Ripon production wells. The increasing concentration trends are most likely caused by current or past pumping activities by these wells. • TCE concentrations in 23 of the 37 groundwater monitoring wells have been stable over time and were below the laboratory reporting limit in 13 of these wells in 2010. • TCE concentrations in seven of the 37 groundwater monitoring wells show a decreasing trend with time. The concentrations of TCE in these wells have decreased to below 12 pg/I in 2010 (Appendix C). • TCE concentrations in well M-17C1 have been inconsistent since monitoring began in 1989 (Appendix C), most likely due to the influence of the City of Ripon recharge basin located approximately 600 feet south of this well. Cis-1,2-DCE • Concentrations of cis-1,2-DCE were present in 24 of the 37 Nestle monitoring wells sampled in 2010, and ranged from 0.51 pg/L (well M-5C2, April) to 250 pg/L (well M- 31 C 1, October). • Cis-1,2-DCE is the primary COC present in the Intermediate Aquifer(Figure 7). • The cis-1,2-DCE (Figure 10) distribution in the Intermediate Aquifer in 2010 is generally consistent with the cis-1,2-DCE distribution between 2006 and 2009. A decrease in the size and location of cis-1,2-DCE suggests attenuation of cis-1,2-DCE mass within the Study Area since 2006 (Figure 10). • Trends for cis-1,2-DCE concentrations in individual wells in the Intermediate Aquifer resemble the TCE trends in the same wells. • Higher concentrations of cis-1,2-DCE as compared to TCE concentrations are observed in Intermediate Aquifer monitoring wells located in the vicinity of the City of Ripon WWTP, e.g. M-20C1, TH-10, M-30C1 and M-31 C1. This observation supports continued intrinsic remediation through reductive dechlorination near the WWTP. • Wells M-6C1 and M-6C2 are the only wells that contain concentrations of cis-1,2-DCE at relatively high levels compared to other Intermediate Aquifer wells which are located in the vicinity of the Site. The presence of cis-1,2-DCE in these wells is most likely due to the operational practices of municipal wells MW-4, MW-6, and the Regal Almond well. VC • VC concentrations appeared in groundwater in 11 of the 37 Nestle groundwater monitoring wells ranging from 0.55 pg/L (wells M-6C1 and M-11 Cl) to 160 pg/L (well M- 54C). f This includes one inactive extraction well. Extraction well E6 was inactive until October 1, 2010. 15