ARCHIVED REPORTS_2013 ANNUAL REPORT

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Nestle USA, Inc., Ripon, California March 26, 2014 2013 Annual Report • All Lab Reporting Limits=0.5 lag/L • * Reported VOCs includes only Nestl6 COCs identified in the 2010 MRP 2.3.1 COC DISTRIBUTION The following subsections present observations regarding the spatial distributions of TCE, cis- 1,2-DCE, and VC in each of the three monitored aquifers. Five-year isoconcentration maps (2009 through 2013) for select COCs and aquifers are provided in Figure 9, Figure 10, and Figure 11. Upper Aquifer • TCE is the most prevalent COC in the Upper Aquifer (Table 5.1). The spatial distribution of TCE concentrations in the Upper Aquifer has not increased over the last five years of monitoring with the exception of an increase in TCE concentration at well M-10A in the Third Quarter 2009. TCE concentrations in some wells near the City of Ripon WWTP, such as well M-32A have decreased during this time period (Figure 9). • To delineate the northwestern extent of the Upper Aquifer plume, ECM installed three new monitoring wells2. Well M-55A was installed in the Locust Avenue right-of-way (ROW) between West Main Street and First Street. Wells M-56A and M-57A were installed northwest of Pine Street at the terminus of the frontage road in the ROW, and completed within two different zones of the Upper Aquifer. Results from well M-55A were consistent with concentrations observed during the M-10A 2011 investigation3. Results from wells M-56A and M-57A were non-detect for VOCs, and define the extent of the northwestern part of the plume in the Upper Aquifer. • The highest concentrations of TCE in the Upper Aquifer (greater than 100 micrograms per liter [tag/L]) were observed in wells EW-1 and M-49A located at the Site and in well M-10A. • Wells located west and southwest of the Site, such as M-14A, M-41A, M-18A, M-55A, and M-9A, contain comparatively higher concentrations of cis-1,2-DCE than wells located near the Site (Figure 6). The presence of higher cis-1,2-DCE concentrations at this location is consistent with continued intrinsic remediation near the WWTP4. Intermediate Aquifer • The most prevalent COC observed in the Intermediate Aquifer is cis-1,2-DCE (Table 5.2). The distribution of cis-1,2-DCE concentrations in the Intermediate Aquifer has not increased over the last five years of monitoring (Figure 10). • Higher concentrations of cis-1,2-DCE, compared to TCE concentrations, are observed in the Intermediate Aquifer monitoring wells located in the vicinity of the City of Ripon WWTP, (e.g., M-17C1, M-21 C1, M-30C1, M-30C2, M-31 C1, M-32C, and TH-10; Figure 7, Figure 10). Wells TH-10, M-30C1, and M-31C1 contain concentrations greater than 100 tag/L (Table 5.2, Table 6, Appendix B). This observation is consistent with occurrence of intrinsic remediation processes in the Intermediate Aquifer near the WWTP. • The distribution of VC concentrations in the Intermediate Aquifer has not increased over the last five years. Decreasing VC concentrations observed in the vicinity of well M-17C1 9