ARCHIVED REPORTS_2013 ANNUAL REPORT

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Stanislaus River. Groundwater generally flows toward pumping wells located north and south of the Stanislaus River. The alluvial aquifer system underlying the Study Area consists of three high-producing water- bearing zones designated as the Upper Aquifer, the Intermediate Aquifer, and the Lower Aquifer. Each of these typically contains more than one water-bearing unit with similar water level elevations and water chemistry. Aquitards consisting of fine-grained silts and clays generally separate water-bearing units. Four stratigraphic intervals are as follows: 1. Upper Aquifer (water table at 20 to 40 feet bgs down to approximately 100 to 115 feet bgs): The B-zone extends from 20 and 45 ft bgs. The underlying A-zone consists of the Upper A- zone (approximately 50 to 80 feet bgs), Middle A-zone (approximately 80 to 95 feet bgs) and Lower A-zone (approximately 100 to 115 feet). 2. Intermediate Aquifer (Approximately 110 to 190 feet bgs): Monitored by Nestle's C1 wells, generally constructed with slotted intervals between 130 to 150 ft bgs and C2 monitoring wells, generally constructed with slotted intervals between 175 to185 feet bgs. 3. Corcoran Clay (178 to 210 feet bgs): A regionally extensive blue-green lacustrine clay forms an aquitard (confining unit). 4. Lower Aquifer (> 210 feet bgs): Nestle's D-level monitoring wells generally screened from 220 to 240 feet bgs. Water below approximately 700 feet bgs is no longer potables A1.8 ON-SITE AND OFF-SITE TCE SOURCE AREAS To date, investigation activities within the Study Area have identified the On-Site source area (the former manufacturing facility) and two main source areas off site (the City of Ripon WWTP, and sewer lines leak near 519 Stockton Ave). The investigation activities included reviews of historical facility operations and waste discharge practices, pumping data from On-Site production wells, groundwater and soil investigation data, soil vapor surveys, and fate and transport modeling. The details of these investigations can be found in the Updated SCM document prepared by AMEC-Geomatrix34 and the 2011 Revised FS Report prepared by ECMss A1.9 SITE REMEDIATION Nestle has completed several remedial activities and tested several remedial technologies including: • Soil vapor and soil remediation, • Source area in situ remediation pilot studies near the extraction wells EI-1 and EW-1 and monitoring wells M-1A and M-113, including injection of a protein substrate in 198936 potassium permanganate in 200037, and a carbohydrate substrate (molasses) in 200538, and • Groundwater remediation by pump and treat. Remediation efforts included targeting removal of COC mass in soil and soil vapor as well as long-term groundwater extraction and treatment in areas of elevated COC concentrations. Some of these areas have been remediated and the details of associated activities can be found in previous reports3s,4o,4, Nestle installed a groundwater extraction and treatment system for well E-2 at the Stockton Avenue (Off-Site) location in 1999. Pumping began at E-6 in 2004. Combined extracted water from E-2 and E-6 was discharged to the City non-potable water system (NPS).