ARCHIVED REPORTS_2011 REVISED FEASABILITY STUDY

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Nestle USA, Inc.—Ripon, CA January 28, 2011 2011 Revised Feasibility Study 99 days, depending on the well sampled. A detailed assessment of this carbohydrate injection study is included in Attachment A.2. The pilot tests of in-situ biodegradation demonstrated that mass removal by injecting chemicals in the subsurface may be feasible as a remediation technology. Considerations of the technical challenges associated with delivering chemicals to promote complete degradation of COCs in the subsurface, and the potential formation of unwanted degradation by-products, require further consideration. Section 9 provides a comparison of the various remedial technologies that have been evaluated for the Study Area. 4 Site Conceptual Model (SCM) 4.1 Summary ECM submitted a SCM to the RWQCB in 2006 which included descriptions of the site geology, hydrogeology and COC distribution in all three defined aquifers" to satisfy the requirements of the CAO. To better understand the process of COC transport from the Site and off-site within the Study Area, AMEC Geomatrix reviewed reports on the regional geology and hydrogeology, historical site operations, reports of subsurface investigations, groundwater monitoring data, historical pumping and groundwater recharge within the area, and updated the SCM in 2009"". The information assembled in the updated SCM is being used to: • develop this Revised FS report, • support the recommendations of this Revised FS report and future remedial actions, and • provide a foundation for the RAP. The updated SCM, summarized below, concludes that COC impacts to groundwater originated from both offsite (upgradient) and onsite (i.e. beneath 230 Industrial Avenue) locations. The updated SCM provides additional assessment of the impact of wastewater lagoons previously operated by Neenah Paper Company (NPC) located south of the Site, and the associated recharge effects of these lagoons on the Upper and Intermediate Aquifers. NPC announced the closure of its manufacturing facility in June 2009. As of October 2010, the former NPC facility is owned by Diamond Pet Food Processors of Ripon, LLC. The future operational plans for these lagoons are unknown. The lagoons located at the City of Ripon's WWTP have received industrial wastewater continuously since the 1930's; this wastewater may have contained TCE and other COCs which are now detected in groundwater samples taken from a number of wells within the Study Area. The high organic carbon content of the industrial and municipal wastewater may have facilitated the breakdown of TCE to cis-1,2-DCE and vinyl chloride (VC) in this area, possibly explaining the relative absence of TCE in the WWTP area. 8