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Lower Aquifer, consisting of the D unit, generally ranging from 190 feet bgs to <br /> approximately 700 feet bgs, below which the water is no longer potable21. <br /> A1.8 ON-SITE AND OFF-SITE TCE SOURCE AREAS <br /> To date, investigation activities within the Study Area have identified the on-Site source area <br /> (the former manufacturing facility) and two main source areas off-site (the City of Ripon WWTP, <br /> and sewer lines leak near 519 Stockton Ave). The investigation activities included reviews of <br /> historical facility operations and waste discharge practices, pumping data from on-Site <br /> production wells, groundwater and soil investigation data, soil vapor surveys, and fate and <br /> transport modeling. The details of these investigations can be found in the Updated SCM <br /> document prepared by AMEC-Geomatrix22 and the 2011 Revised Feasibility Study report <br /> prepared by EC M23. <br /> A1.9 SITE REMEDIATION <br /> Nestle has completed and considered several remedial activities including: <br /> • Soil vapor and soil remediation, <br /> • Source area in situ remediation pilot studies near the extraction wells EI-1 and EW-1 and <br /> monitoring wells M-1A and M-113, including injection of a protein substrate in 198924, <br /> potassium permanganate in 200025, and a carbohydrate substrate (molasses) in 200526, <br /> and <br /> • Groundwater remediation by pump and treat. <br /> Remediation efforts have included targeting removal of COC mass in soil and soil vapor as well <br /> as long-term groundwater extraction and treatment in areas of elevated COC concentrations. <br /> Some of these areas have been remediated and the details of associated activities can be <br /> found in previous reports27,2s,2s. The following is a summary of the groundwater extraction and <br /> treatment activities completed at Industrial Avenue and Stockton Avenue. <br /> Industrial Avenue Extraction and Treatment System <br /> Extraction wells EW-1 and EI-1 provided groundwater removal at Industrial Avenue between <br /> 1995 and February of 2008. In December 2007, ECM installed two new groundwater extraction <br /> wells (EU-3 and EU-4) at Industrial Avenue. These new wells were installed to more precisely <br /> target COC concentrations for source removal and hydraulic control at the Site to prevent or <br /> limit migration. Extraction from wells EW-1 and EI-1 ceased in February 2008, once EU-3 and <br /> EU-4 commenced pumping. A complete discussion of the IRAP groundwater extraction and <br /> treatment system, which began operation in February 2008, can be found in the Interim <br /> Remedial Action Plan, Well Installation and Aquifer Test Report30 and the Interim Remedial <br /> Action Plan Groundwater Extraction System Startup Report 31. <br /> ECM resumed extraction from well EI-1 on October 29, 2010, as a result of the M-10A <br /> investigation32, to target mass removal and provide containment in the "lower A zone" (100 feet to <br /> 115 feet bgs) of the Upper Aquifer. <br /> Stockton Avenue Extraction and Treatment System <br /> Nestle installed a groundwater extraction and treatment system for well E-2 at the Stockton <br /> Avenue location in 1999. Well E-6 was add to the Stockton Avenue extraction and treatment <br /> Appendix A <br /> Page A4 of A7 <br />