ARCHIVED REPORTS_RESPONSE TO COMMENTS ON DRAFT REMEDIAL ACTION PLAN 2015

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Page 2 The Draft RAP must be revised to clearly indicate Central Valley Water Board staff has not concurred with MNA as part of the final groundwater remedy. Furthermore, the Draft RAP should be revised to indicate the on-going MNA Study needs to 1) demonstrate MNA can restore groundwater in a reasonable timeframe and 2) be protective of human health and groundwater quality before we can concur with it as part of the groundwater remedy. Assuming Nestle is able to successfully demonstrate that MNA is viable and should be part of the final groundwater remedy, the existing groundwater monitoring network will still need to be augmented before MNA can be implemented as part of the final remedy. In addition,Nestle must propose very conservative triggers for active remediation. For example, if groundwater monitoring data indicates Nestle's groundwater contaminants are migrating towards receptors south of the Stanislaus River, Nestle must quickly implement hydraulic containment and/or other remedial actions to stop the migrating contaminants.Without these safeguards in-place, MNA will not be sufficiently protective and Central Valley Water Board staff will not support it in the Final RAP. Nestl6 Response: The Draft RAP must be considered in the context of the work that Nestle performed on this site dating back to 1986, including years of soil vapor and groundwater extraction and multiple in situ remediation pilot projects. Based on the 2011 Feasibility Study, the Draft RAP proposed evaluating and potentially including MNA as part of an overall remedy that: • augments the active remediation implemented to date by Nestle. Nestl6 has operated groundwater treatment systems that actively performed source removal, including vapor extraction and groundwater remediation, treating more than 2.5 billion gallons of groundwater since 1986, • proposes hydraulic containment in areas where natural attenuation is not considered to be adequate (e.g. M-l0A area), and • protects receptors through water replacement, conduit decommissioning and/or wellhead treatment(Please refer to the Water Replacement Contingency Plan (WRCP); Nestl6 proposed the MNA study to assess the timeframe for groundwater remediation by natural attenuation and the overall protectiveness of the natural attenuation processes. Nestl6 already initiated work under the Water Board-approved MNA Work Plan and will continue the activities as per the approved plan to provide information that will be used to assess the timeframe for groundwater restoration by natural attenuation. The MNA study will specifically assess whether active remedies are needed in certain areas if natural attenuation processes are not sufficiently protective of receptors. While the study is being undertaken, receptors will continue to be protected with groundwater extraction and treatment under an interim remedial action and also by compliance with the WRCP. Upon completion of the five year MNA study, the RAP will be revised and finalized. Triggers will be included in the Final RAP as the Water Board requested. However, as shown in the 2011 Feasibility Study, it does not appear to be feasible to "quickly implement hydraulic containment and/or other remedial actions"based on the current understanding of groundwater