ARCHIVED REPORTS_2010 ANNUAL REPORT

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Nestle USA, Inc., Ripon, California March 31, 2011 2010 Annual Report process and are not associated with Nestle activities. All COC results were below the laboratory detection limits in MW-18 in 2010 except cis-1,2-DCE (7.4 pg/L), TCE (3.2 pg/L) and 1,1-DCA (0.1 pg/L) in the sample collected on January 19, 2010. Since no prior or subsequent samples have contained concentrations of a COC, ECM believes this to be an anomalous result. No other samples collected in 2010 contained VOCs above their respective laboratory reporting limits (Table 4). 3.5 DISCUSSION OF INTRINSIC REMEDIATION ASSESSMENT RESULTS ECM submitted a subset of the groundwater samples collected during the second and third quarterly groundwater monitoring events for additional chemical analyses to assess intrinsic remediation (IR) for the 2011 Revised FS19. On April 26 and 27, 2010, during the Second Quarter sampling event, ECM sampled 13 wells in the Upper and Intermediate aquifers for IR parameters using low flow purging and sampling techniques. After the review of the Second Quarter results, the program was expanded to include 10 additional monitoring and extraction wells, screened within the Upper Aquifer zone (four B-zone wells, two onsite operating extraction wells, and four A-zone monitoring wells), Intermediate Aquifer monitoring well M-8C1, and five Lower Aquifer monitoring wells. On August 2, 3, and 5, 2010, during the Third Quarter sampling event, ECM sampled 28 wells for IR parameters. Sampling personnel collected field parameters including concentrations of dissolved oxygen, carbon dioxide, and the standard field parameters (temperature, conductivity, pH, and oxidation- reduction potential [ORP]). ECM submitted groundwater samples to TestAmerica for dissolved metals, ions, dissolved gases and total organic carbon (TOC) and to ZymaX Environmental Forensics Laboratories, of Escondido, California (ZymaX) for VOC and compound specific isotope analysis (CSIA). A summary of the analytical results for the IR sampling events was presented in Table 6 of the Second Quarter 2010 Site Status Report20 and Third Quarter 2010 Site Status Report21. The laboratory analysis indicates strongly reducing groundwater conditions near the WWTP (i.e. within approximately 1,000 feet of the WWTP) in the Intermediate Aquifer zone and lower A- zone of the Upper Aquifer. These conditions are favorable for TCE destruction by dehalorespi ration, where indigenous microbes convert TCE to less chlorinated and eventually non-chlorinated degradation products under anoxic conditions. As groundwater moves farther away from the WWTP, data indicate that conditions become less reducing such that dehalorespi ration is not likely to be an important COC destruction process, although other degradation mechanisms could be more active under these conditions. Active degradation of CDCs by methods other than dehalorespi ration are difficult to assess by analyzing conventional groundwater data. Therefore, CSIA was used to provide direct evidence of COC destruction that could not be obtained previously. The CSIA data indicate that greater than 90% destruction of COCs has already occurred. The half-life for CDCs in groundwater near the WWTP is estimated to be approximately 0.5 years, which is consistent with the range in values reported for other sites under similar conditions. Therefore, based on the interim assessment, intrinsic remediation appears to be occurring within the Study Area. 4 ONGOING REMEDIAL ACTION ECM operated, maintained, and monitored the Industrial Avenue extraction and treatment system and the Stockton Avenue extraction and treatment system in 2010. Descriptions of the extraction and treatment systems with flow diagrams are presented in Appendix G. 19