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Addendum to Proposed Remediation Well Installation Work Plan <br /> Stockton Charter Way Commingled Plume #CP0057 <br /> May 2, 2025 <br /> LTCP groundwater criteria. This additional well brings the total number of wells to be installed to <br /> three, at the locations shown in Figure 2. <br /> 2.1 PRE-FIELD ACTIVITIES <br /> 2.1.1 Health and Safety <br /> No changes to the health and safety plan will be necessary to implement this additional proposed <br /> ART well.See the previous Stantec workplan dated February 27,2025,for health and safety details. <br /> 2.1.2 Permitting and Utility Clearance <br /> Permitting and utility clearance will be updated to include the additional ART well. See the <br /> previous Stantec workplan dated February 27, 2025, for permitting and utility clearance details. <br /> 2.2 PROPOSED WELL INSTALLATION DETAILS <br /> An additional ART well (ART-1 1) will be installed in conjunction with the previously approved wells <br /> (ART-9 &ART-10) in accordance with San Joaquin County Environmental Health Department <br /> (SJCEHD) Well Standards and permit requirements. As previously proposed, borings for the ART <br /> wells will be advanced using a sonic drilling rig equipped with heavy-walled down-hole 12-inch <br /> casing telescoped to help seal off shallower groundwater-bearing zones. Cores will be <br /> evaluated for continuous soil stratigraphy. Soil cores will be classified using the Unified Soil <br /> Classification System under the direction of a State of California Professional Geologist. Soil cores <br /> will be screened in the field for the presence of volatile organic compounds (VOCs) using a <br /> photo-ionization detector (PID). Soil classifications, VOC measurements, sample intervals, and <br /> other pertinent geologic information will be recorded on soil boring logs. Down-hole drilling <br /> equipment will be decontaminated with high pressure steam following the completion of each <br /> soil boring. Down-hole sampling equipment will be decontaminated between samples using an <br /> Alconox detergent solution and a tap water rinse. Decontamination water will be collected <br /> within a decontamination pad and will be containerized in drums for subsequent disposal. <br /> At the terminal depth of each well boring, an ART remediation 6-inch diameter well will be <br /> installed within the drill casing.Table 1 summarizes the anticipated well construction details for <br /> the newly proposed remediation well (ART-11); however, these details may be modified in the <br /> field based upon the actual soil stratigraphy encountered. A sand filter pack will be placed in <br /> the annular space surrounding the entire screened intervals and will extend approximately two <br /> foot above the top of the screened interval. A bentonite annular seal will be placed and extend <br /> approximately two feet above the filter pack and hydrated as well as below the top screened <br /> interval. The remainder of the annular space will be filled with cement and/or grout from the top <br /> of the bentonite seal to within 12 inches of the surface. The wells will be temporarily secured with <br /> a locking well cap and completed with a watertight traffic-rated well box installed at grade. <br /> After a minimum of 48 hours following the well construction, the newly constructed wells will be <br /> developed to clean and stabilize the filter pack around the slotted well casings. Development <br /> 5 Stantec 3 <br />