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Monitoring Well Installation Report April 15, 2010 <br /> Former Nestle USA, Inc. Facility, Ripon, CA <br /> utility clearance activities on all three parcels on December 3, 2009. ECM also <br /> requested Subtronic to provide additional utility clearance on December 16, 2009, at <br /> both the Stockton and Industrial locations due to the fact that two of the five wells (M- <br /> 50A and M-52B) required relocating because of their proposed location proximity to <br /> overhead or subsurface utilities. <br /> Prior to advancing any mechanized equipment, both Boart Longyear and Gregg Drilling <br /> personnel hand augured the first four feet of soil to confirm the absence of shallow <br /> utilities. <br /> 4 FIELD ACTIVITIES <br /> Field activities commenced on December 7, 2009, beginning with the Fifth Street drilling <br /> location (M-54C). ECM personnel were on-site with Boart Longyear from December 7 <br /> through December 9, 2009 for the installation of M-54C. ECM field personnel were <br /> again onsite from December 14 through December 21, 2009 for the drilling and <br /> installation of wells M-50A, M-51A, M-5213, and M-53B with Gregg Drilling. <br /> The following sections describe soil boring activities, groundwater sampling, and general <br /> well construction for each of the wells. The wells in the following sections are discussed <br /> in chronological order of drilling and installation. Boring logs are provided in Appendix <br /> C. Well completion details are illustrated in Appendix D and in Table 1. <br /> 4.1 MONITORING WELL M-54C <br /> Drilling activities for monitoring well M-54C by means of sonic drilling commenced on <br /> December 7, 2009. The location of this well in Fifth Street (Figure 2), south of the 519 <br /> South Stockton Avenue Site, was selected to monitor potential upgradient contamination <br /> emanating from the City of Ripon municipal lagoons in the Intermediate Aquifer. <br /> 4.1.1 STRATIGRAPHIC CHARACTERIZATION <br /> The sonic drilling method employed the use of 7-inch nominal outer diameter (O.D.) <br /> borehole casing with a 6-inch O.D. core barrel for collecting continuous soil cores from <br /> the M-54C borehole. Cores were advanced at an interval of 10 to 20 feet. Observations <br /> made from the soil cores included lithologic description, soil color, Unified Soil <br /> Classification System ranking, and field observed moisture content. The lithologic log <br /> from M-54C can be found in Appendix C. <br /> Fine to medium grained subrounded sands interbedded with silts and silty fine-grained <br /> sands were observed to a depth of 175 feet bgs. Clayey silts were observed from 175 to <br /> 185 feet bgs. <br /> 4.1.2 GROUNDWATER SAMPLING <br /> The borehole for well M-54C was not sampled during drilling activities because the well <br /> screen interval had been predetermined based on historic sampling data in other <br /> Intermediate Aquifer wells. However, the completed well was vertically profiled by using <br /> PDB sampling method in January 2010. The data for this sampling event will be <br /> discussed in detail in the Section 7. <br /> 3 <br />