ARCHIVED REPORTS_2011 REVISED FEASABILITY STUDY

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Nestle USA, Inc.—Ripon, CA January 28, 2011 2011 Revised Feasibility Study gas surveys, a second SVE system was installed in 1992 at 519 South Stockton Avenue" The Site SVE system was expanded to include a total of eight vapor extraction wells in 1992. These additional wells focused on extracting vapors from TCE- and chloroform-impacted areas near suspected chemical releases on the eastern portion of the Site. In 1998, four new SVE wells and a new vapor treatment system were installed to focus vapor extraction activities in the area of highest remaining TCE concentrations near the former decaffeination building. The SVE systems removed an estimated 880 pounds of VOCs (primarily TCE and chloroform) from the subsurface between 1988 until the discontinuation of SVE prior to 1994. Complete documentation and an assessment of the SVE activities in the area of the Site are included in Attachment A.3. As indicated in the attachment, the historical SVE remediation activities resulted in remediation of the vadose zone (within the upper portion of the B-zone beneath the Site). 3.4.2 Groundwater Remediation Groundwater remediation efforts first began in January 1986. Four onsite production wells (N-1, N-2, N-3 and N-4) supplied water for manufacturing processes at the former facility. N-1 supported the manufacturing process. N-2 operated intermittently because of high total dissolved solids (TDS), according to personal communication with John Meling, former plant engineer. Well N-3 was used for tea processing from 1962 through 1974, with backup production from well N-4 (this operating information was also obtained through personal communication with John Meling). In January 1986, routine sampling and analysis of N-1 and N-2 revealed TCE in the groundwater samples from these wells. In May 1986, COCs were detected in groundwater samples obtained from municipal wells MW-1 and MW-6, located near the Site. Subsequent to these findings, operation of municipal well MW-1 was terminated and this well was decommissioned. Following notification to the appropriate regulatory agencies (Section 3.3), Nestle constructed a GAC system at the northern corner of the Site in July 1986 to treat groundwater extracted from well N-1. Expanded groundwater extraction and treatment at the Site incorporated well EW-1, installed in 1992, and well EI-1, which replaced well N-1 after its closure in 1994. Both of these wells are screened at approximately 100 to 120 feet below ground surface (bgs) within the lower portion of the A-zone aquifer. Extraction from these wells has mitigated plume migration and removed COC mass within this zone. Following the 2005 investigation activities (by Geomatrix Consultants, Inc.), ECM installed wells EU-3 and EU-4 to focus mass removal and hydraulic control activities within the upper portion of the A-zone beneath the Site. Groundwater extraction within the upper A-zone also provides hydraulic containment and influence in the area of well M-1 B (screened within the B-zone (20 to 40 feet bgs)) beneath the site"' Wells EU-3 and EU-4 began pumping at 30 gpm each in February 2008. With approval from the RWQCB, groundwater extraction at well EI-1 was discontinued when well EU-3 and EU-4 began operating. Additional documentation of IRAP groundwater extraction and treatment system 5