ARCHIVED REPORTS_MONITORING WELL INSTALLATION REPORT 2010

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Monitoring Well Installation Report April 15, 2010 Former Nestle USA, Inc. Facility, Ripon, CA 4.1.3 WELL COMPLETION DETAILS Well M-54C was completed to a depth of approximately 175 feet bgs and the well completion log is presented in Appendix D. The well was constructed of two-inch polyvinyl chloride (PVC) Schedule 40 casing with 20 feet of 0.020-slot screen from approximately 155 to 175 feet bgs. 4.2 MONITORING WELL M-51A Drilling for monitoring well M-51A commenced on December 14, 2009, on the northern portion of the 230 Industrial Avenue parcel, just south and east of the former Nescafe water tower (Figure 2). Figure 3 illustrates the location of this new well in relation to other wells at the Industrial Avenue location. 4.2.1 STRATIGRAPHIC CHARACTERIZATION To get a clear picture of the lithology in the target well screen zone, split spoons were advanced ahead of the Simulprobe°sampler at certain intervals during the drilling of well M-51A. As illustrated in the lithologic log in Appendix C, silty sands, interbedded clayey sands, sandy clays, and poorly sorted sands were observed during drilling by logging drill cuttings, split spoon samples, and Simulprobe° core samples. This borehole was terminated at 70 feet bgs. 4.2.2 GROUNDWATER SAMPLING An attempt was made to collect a groundwater sample with the Simulprobe° sampler at a depth of approximately 53.5 feet bgs. However, due to the presence of high silts in the target zone, the sampling screen became clogged and a groundwater sample was not obtained. The Simulprobe° sampler was driven another 18 inches and a sample of groundwater was successfully obtained at 55 feet bgs. This sample was collected to target a discrete sand interval in the Upper Aquifer which previously showed a TCE concentration of 3,300 micrograms per liter (µg/L) during a August 2005 Cone Penetration Test investigation (CPT-1). The groundwater sample was immediately placed in a cooler on ice. The sample, labeled M-51A-55', was transported to TestAmerica in Pleasanton, California for analysis of volatile organic compounds (VOCs) by EPA Method 8260B. A complete discussion of laboratory analytical results is provided in Section 7. 4.2.3 WELL COMPLETION Monitoring well M-51A was completed to a depth of 67 feet bgs. The well was constructed of two-inch PVC Schedule 40 casing with 15 feet of 0.020-slot screen from approximately 52 to 67 feet bgs. Well completion details are illustrated in Appendix D and on Table 1. 4.3 MONITORING WELL M-53B Drilling for monitoring well M-53B commenced on December 16, 2009, in the north- eastern corner of the 519 South Stockton Avenue parcel, just west of the property line fence (Figure 2). The focus of the investigation for well M-53B was to collect discrete interval samples from multiple target zones throughout the B Zone of the Upper Aquifer. 4