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Nestle USA, Inc., Ripon, California March 31, 2011 <br /> 2010 Annual Report <br /> Presently, all City of Ripon potable water comes from groundwater aquifers". In a meeting <br /> held on November 9, 2010, the City of Ripon informed Nestle and the RWQCB that they are <br /> currently in negotiation with the City of Lathrop to acquire rights for treated water from the <br /> Nick DeGroot Surface Water Treatment facility18. This would reduce City of Ripon <br /> dependence on groundwater by up to 50%. Future well location and volume of water pumped <br /> may have some effect on Nestle's remediation effort. To minimize this impact, it is important <br /> that Nestle continue coordination of water management efforts with the City of Ripon. <br /> COC concentrations were reported in three City of Ripon wells, (MW-3, MW-7, and MW-9, <br /> Table 4) in 2010. For the municipal wells in which COCs were detected, the levels of CDCs <br /> present were below state and federal maximum contaminant levels (MCLs). The appearance <br /> and increase in COC concentrations in well MW-3, beginning in February 2007, is most likely <br /> attributed to the increase in pumping at the well. The highest TCE concentration detected in <br /> this well was 0.73 lag/L during the January 2010 sampling event. Cis-1,2-DCE concentrations <br /> ranged from 1.7 lag/L (July) to 1.3 lag/L (April). Chloroform, persistent since October 2005, was <br /> present in all four quarterly samples and ranged from 0.24 lag/L to 0.32 lag/L. <br /> Municipal Well MW-3 <br /> 10.00 180 <br /> All concentrations were non- 160 <br /> detect through October 2006. <br /> Vinyl chloride has remained 140 <br /> CL non-detect through present <br /> 1.00 and is not represented on 120 - <br /> = p ° ° ° L <br /> Ul ° 100 <br /> 0 0 ° ° ° �. <br /> 80 <br /> v 0.10 �]� 60 :3 <br /> C VJ <br /> O O <br /> U ° A 40 ca <br /> O <br /> 20 0 <br /> N <br /> 0.01 0 <br /> Oct-06 Apr-07 Nov-07 Jun-08 Dec-08 Jul-09 Jan-10 Aug-10 Feb-11 <br /> A TCE ° CIS —MW-3 Municipal Pumping <br /> Concentrations of CDCs were first detected in well MW-9 in August 1993 (Appendix B). The <br /> highest TCE (8.3 lag/L) and cis-1,2-DCE (9.8 lag/L) concentrations observed were reported in <br /> April 1998. The maximum VC concentration (0.6 lag/L) was reported in April 2002. COC <br /> concentrations have decreased since 1998. This well is equipped with a GAC well-head <br /> treatment system. <br /> Bromoform, bromodichloromethane, and dibromochloromethane reported in wells MW-7 and <br /> MW-10 are likely the byproducts of the typical disinfectants used in the chlorination disinfection <br /> 18 <br />