ARCHIVED REPORTS_2013 ANNUAL REPORT

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Nestle USA, Inc., Ripon, California March 26, 2014 2013 Annual Report o The RWQCB will provide comments on the 2011 FS by early 2014'. o The Ripon Team will revise the MNA work plan (not yet submitted to the RWQCB) and submit a draft to the RWQCB for review. o The Ripon Team will begin working on the details of the extraction well installation and reinjection as the primary discharge alternative, since the RWQCB indicated that discharging treated water to the river was not an option. The meetings were constructive and contributed to project planning and implementation. The monthly status calls will continue in support of this accord. 4.6 MONITORING AND REPORTING PLAN UPDATES On November 2, 2012, ECM submitted the Request for Revising the Monitoring and Reporting Program #R5-2010-0810 (MRP) on Nestle's behalf. The proposed modifications to the MRP were based on an evaluation of historical data, including the distribution and concentration trends of COCs. During the monthly meeting in May 2013, the RWQCB requested the Team use a consistent decision logic approach to support the proposed MRP recommendations and to develop future recommendations. In response to this request, the project team evaluated several options, including proprietary computer software and implementing the decision logic approach presented in the Interim Final Guide to Optimal Groundwater Monitoring prepared for the Naval Facilities Service Center, Port Hueneme, California 12. The Team decided to use The Interim Final Guide to Optimal Groundwater Monitoring, which presents a consistent, flow-chart-based approach to support long-term monitoring optimization (LTMO) in the future. Pursuant to the discussion of the MRP status with RWQCB staff during the October 2013 meeting, the RWQCB sent ECM a draft copy of the MRP table on November 11, 2013. ECM is currently reviewing the table and will send comments and recommendations to the RWQCB by the end of February 2014. ECM anticipates that the new MRP will be implemented in Second Quarter 2014. 4.7 2013 GROUNDWATER MODEL UPDATE In 2006, ECM developed a groundwater flow and transport model for the Study Area13. In 2011, ECM performed an update of the model, including the input parameters, to ensure that the model calibration and predictive capabilities remained valid for current hydrogeologic and TCE plume conditions beneath the Study Area. The model was updated again in 2013 as part of a planned biennial update process. Key improvements to the model include the following: • Bottom elevations in layers 3 and 4 in the M-10A area of the model were refined using stratigraphic information from the 2011 M-1 OA investigation and 2013 well installations. • Observed Stanislaus River stage corresponding with the same day as the quarterly groundwater monitoring event was used in each quarterly stress period of the model. This approach improved hydraulic parameter calibration for the upper layers in the model Nestle received comments on January 8, 2014. 19