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Monitoring Well Installation Report April 15, 2010 <br /> Former Nestle USA, Inc. Facility, Ripon, CA <br /> shortly thereafter and indicated they would commence excavation activities the following <br /> morning to repair the line. The City of Ripon indicated they would need to excavate <br /> below the line, so the borehole grout depth was terminated at 10 feet bgs. <br /> ECM identified a new location for the M-50A well. This location was approximately 10 <br /> feet south of the first location, located inside the gated, landscaped area of the 230 <br /> Industrial Avenue property. A new USA Ticket number was requested (#386842) and <br /> Subtronic was contracted to mark-out the new location on December 16, 2009. <br /> 4.4.2 STRATIGRAPHIC CHARACTERIZATION <br /> Drilling in the new location for well M-50A commenced on December 18, 2009. Silty <br /> sands were observed in drill cuttings from surface to approximately 27 feet bgs. Silts <br /> with clayey sands and sandy clays were observed in cuttings from 27 to 44 feet bgs. An <br /> attempt was made to advance the Simulprobe°sampler at 44 feet bgs, however heaving <br /> sands prevented the use of the Simulprobe°. As indicated in Section 2.2, a hydropunch <br /> sample was collected in lieu of using the Simulprobe°. Although no lithologic sample <br /> was recovered at this depth, drill cuttings indicated fine to coarse sands to a depth of 65 <br /> feet bgs. The lithologic log for M-50A is located in Appendix C. <br /> 4.4.3 GROUNDWATER SAMPLING <br /> A hydropunch sample (M-50A-45'-46) was collected at a depth of 45 to 46 feet bgs on <br /> December 18, 2009. This sample was collected to target a discrete sand interval in the <br /> Upper Aquifer which previously showed a TCE concentration of 310 µg/L when <br /> investigated during the drilling of nearby boring B-2 in May 2007. The sample was <br /> immediately placed in a cooler on ice for transport to TestAmerica for analysis of VOCs <br /> by EPA Method 8260B. Results of the analysis are discussed in Section 7. <br /> 4.4.4 WELL COMPLETION DETAILS <br /> Monitoring well M-50A was completed to a depth of 65 feet bgs. The well was <br /> constructed of two-inch PVC Schedule 40 casing with 15 feet of 0.020-slot screen from <br /> approximately 50 to 65 feet bgs. Well completion details for M-50A are illustrated in <br /> Appendix D and on Table 1. <br /> 4.5 MONITORING WELL M-52B <br /> Monitoring well M-52B was installed on the northeast portion of the 519 South Stockton <br /> Avenue property, in the driveway entrance. M-52B was moved 15 feet to the west of its <br /> original field-spotted location due to the proximity of that location to overhead high- <br /> tension wires and a ground-based electrical transformer. Because of the change in <br /> location, Subtronic remarked the site subsurface utilities on December 16, 2009. Drilling <br /> in the new location commenced on December 20, 2009. As with M-53B, the focus of the <br /> investigation for M-52B was to collect discrete interval samples from multiple target <br /> zones throughout the B Zone of the Upper Aquifer. <br /> 4.5.1 STRATIGRAPHIC CHARACTERIZATION <br /> Silty sands were observed in drill cuttings from surface to approximately 20 feet bgs. <br /> From 20 to 25 feet bgs, fine (-10 millimeter) gravels were observed in cuttings along <br /> with silty sands. The deeper lithology of this borehole included fine to medium-grained <br /> 6 <br />