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2012 Monitoring Well Installation Work Plan <br /> Former Nestle USA, Inc.Facility November 8, 2012 <br /> opposed to the coarse-grained sands of the Upper A zone. The base of the Upper Aquifer (and <br /> therefore the base of the Lower A zone) is generally characterized by the presence of brown <br /> and/or grey silty clays. <br /> Based on a review of boring logs from CPTs drilled in the vicinity of the proposed well locations, <br /> the screened interval of M-56A will likely be five to ten feet in length and installed between <br /> approximately 55 and 70 feet bgs. The screen interval of M-55A and M-57A will be of similar <br /> length and between approximately 105 and 120 feet bgs. Soil cores will be collected <br /> continuously from approximately 50 to 120 feet bgs during drilling and characterized using <br /> visual-manual methods according to the Unified Soil Classification System to guide in the <br /> selection of the screen intervals. The monitoring well screens will be placed at depth intervals <br /> that overlap the depth intervals where groundwater samples with the highest COC <br /> concentrations were identified during the 2011 CPT investigationlal. As such, the target screen <br /> interval for M-55A will be in the same lithologic zone where Lower A zone samples were <br /> collected at CPT-34 (106 feet bgs) and CPT-39 (108 feet bgs). Similarly, the target screen <br /> intervals for M-56A and M-57A will be in the same lithologic zone where samples from CPT-36 <br /> were collected at 55 feet bgs and 108 feet bgs, respectively. <br /> 3 MONITORING WELL INSTALLATION PLAN <br /> 3.1 PERMITS AND DRILLING <br /> ECM will obtain well permits from the San Joaquin County Environmental Health Department <br /> (SJCEHD). In addition, ECM will obtain Encroachment Permits from the City of Ripon to install <br /> these wells in the municipal rights-of way (ROWs). <br /> ECM will mark the drilling areas in white paint and will notify Underground Service Alert of <br /> Northern California at least two working days prior to drilling. ECM will also use a private utility <br /> locating company to identify and mark underground utilities. A Traffic Control Plan will be <br /> required for the City of Ripon Encroachment Permits and will be submitted with the permit <br /> application. <br /> Before advancing any drill steel, a State of California licensed drilling contractor will hand auger <br /> the first five feet of soil to confirm the absence of shallow utilities. Soil borings for the purpose <br /> of monitoring well installation will be advanced using a rotosonic or hollow stem auger drill rig. <br /> Continuous cores will be collected for logging purposes. The borings will be advanced to <br /> approximately 120 feet bgs tbl. The depths may be adjusted in the field in response to conditions <br /> encountered during drilling. An experienced field geologist, under the supervision of a <br /> California-licensed professional geologist or civil engineer, will oversee the drilling. All drilling <br /> equipment will be decontaminated according to standard steam cleaning procedures prior to <br /> use. <br /> a Environmental Cost Management, Inc. M-10A 2011 Investigation Report, Former Nestle USA, Inc. Facility <br /> Ripon, CA-95366. March 29, 2012. <br /> b M-56A may be installed as a nested well with M-57A This would mean the total depth of the borehole will be <br /> 120 feet bgs. However, if M-56A is advanced in its own borehole, the terminus of the boring will be <br /> approximately 70 feet bgs. <br /> Page 2 of 4 <br />