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WORK PLAN FOR GROUNDWATER INVESTIGATION <br />Chevron Service Station # 94054 <br />Stockton, CA <br />October 26, 2016 <br /> <br />3.3 SUBSURFACE UTILITY CLEARANCE <br />Prior to scheduled field work activities, Stantec will mark the locations of proposed groundwater <br />monitoring wells MW-15, MW-16B, and MW17B in accordance with Underground Services Alert <br />(USA) guidelines. Stantec will contact USA North at least 48 hours prior to the start of field work to <br />allow USA members to mark subsurface utility locations. Additionally, Stantec will contact a <br />private utility locator to verify the locations of marked USA member utility lines and investigate <br />the presence of utility lines that are not owned or operated by USA members. All soil borings will <br />be cleared to greater than eight feet below ground surface by air-knife and vacuum extraction <br />prior to using hollow stem auger drilling to complete the borings. <br /> <br />3.4 FURTHER PLUME DELINEATION <br />In order to provide further plume delineation in the areas indicated in the CVRWQCB August 15, <br />2016 letter (summarized in Section 1.0), the following additional groundwater monitoring wells will <br />be installed: <br />One additional A zone well (MW-15) for vertical and horizontal plume delineation to the <br />east of the source area in the parking lot of Kwikee Foods <br />Two additional B zone wells, one to the west of MW-10 (MW-16B) and one to the north of <br />MW-11 (MW-17B) <br />The following table summarizes additional delineation monitoring well design specifications. <br />Proposed well locations are illustrated on Figure 3. <br />Well ID Water <br />Zone <br />Borehole <br />Depth <br />(ft bgs) <br />Well <br />Diameter <br />(inches) <br />Tentative Well Screen <br />Intervals <br />(ft bgs) / Length (ft) <br />MW-15 A 30 2 15-30/15 <br />MW-16B B 50 2 40-50/10 <br />MW-17B B 50 2 40-50/10 <br />3.41 Soil Boring Advancement for Remediation/Groundwater Well Installation <br />Prior to drilling, well borings will be air-knifed to greater than 8 ft bgs to investigate that no <br />unidentified underground facilities exist within the area of drilling. A total of three groundwater <br />monitoring wells (MW-15, MW-16B, and MW-17B) will be installed in accordance with the SJCEHD <br />Well Standards (SJCEHD, 2005). Each boring will be advanced using a hollow-stem auger rig <br />equipped with 8" hollow stem augers. Soil samples will be collected five foot intervals and be <br />evaluated for soil stratigraphy. Soil samples will be classified using the Unified Soil Classification <br />System by a geologist under the direction of a State of California Professional Geologist. Soil <br />samples will be screened in the field for the presence of volatile organic compounds (VOC) <br />using a photo-ionization detector (PID). Soil classifications, VOC measurements, sample intervals, <br />and other pertinent geologic information will be recorded on soil boring logs. Down-hole drilling <br />Stantec <br />4