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0 0 Well Installation Work Plan Summary' Geosyntec Consultants—April 2014 Well Installation Groundwater to the east of the former John Taylor Fertilizers Company (JTF) facility at 1819 South Argonaut Street (Figure 1) is required to be monitoring by the Central Valley Regional Water Quality Control Board with one proposed groundwater monitoring well (Figure 2). Two new groundwater monitoring wells will be installed with the objective of monitoring water levels and concentrations of 1,2- DCP and 1,2,3-TCP downgradient of the JTF facility. Monitoring well screen intervals will target the coarse-grained units within the 70 to 100 feet below ground surface (ft bgs)range. One monitoring well is proposed to be installed in the sidewalk along the east side of South Stockton Street, between West 2nd and West 3rd Streets (MW-12), and one monitoring well is proposed to be installed next to the southbound Interstate 5 on-ramp from West Charter Way(MW-13). The South Stockton Street well will target the 70 to 90 feet bgs range,while the Interstate 5 on-ramp well will target the 80 to 100 feet bgs range. Drilling will be performed using sonic technology with telescoping drill pipe to prevent potential cross- communication between shallow and deeper water-bearing zones. After the target depth has been achieved, monitoring wells will be constructed through the center of the drill pipe. Wells will be constructed using 2.5-inch diameter Schedule 80 polyvinyl chloride (Sch 80 PVC) casing with flush threaded joints. The total depth of the well and the screen intervals will be selected in the field based on observed soil conditions during logging activities. The screen interval length will be approximately 10 feet long. The well screen slot size will be finalized pending evaluation of boring logs and will consist of 2.5-inch diameter Sch 80 PVC with either a 0.010- or 0.020-inch factory slotted screen and a flush- threaded bottom cap. After the casings are installed, the annular space between the borehole wall and the well screen will be filled with a graded silica sand filter pack to approximately 2 feet above the top of the well screen. Approximately 2 feet of bentonite pellets will be placed above the sand pack and allowed to hydrate for a minimum of one hour. A neat cement grout will be placed above the bentonite to ground surface. The filter pack, bentonite pellets, and neat cement grout will be placed via tremmie pipe as the drill pipe is slowly removed. All grouting will be conducted in accordance with San Joaquin County Environmental Health Department requirements. Wells will be completed at the surface with flush-mounted, traffic-rated well boxes, and the tops of the well casings will be fitted with expandable-gasket lockable caps. Well MW-12 will be completed flush with the surface of the sidewalk. Well MW-13 will be completed with the well vault 1 Geosyntec Consultants, 2013. Deeper Downgradient Monitoring Well Installation Work Plan, John Taylor Fertilizers Company, 1819 South Argonaut Street, Stockton, California, 12 March 2013.