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Extraction Well Design <br /> Proposed Dewatering Project, Clearwater Group <br /> 1817 South Fresno Avenue, Stockton, California <br /> Pour dewatering wells will be installed, which will: <br /> • Be spaced approximately 40 feet apart, <br /> • Be drilled using a 2 foot (244nch) auger, � s L <br /> • Be advanced to the depth of the plume, from 20 to 30 feet below ground surface (bgs) . <br /> • Have an 8-inch Schedule 40 PVC well casing, with 0.010 machine-slotted screen placed across <br /> the lower 15-foot groundwater producing zone, with the intention of producing a radius of <br /> influence of between 25 and 40 feet, <br /> • Have a sandpack of #2/12 sand separating the screened interval from native materials and <br /> extending from the bottom of the boring to two feet above the screen, to prevent dredging of fine <br /> materials by the well, <br /> • Have a minimum 5 feet (or longer) of tremmie-grouted bentonite slurry above the sandpack, with <br /> 30% solids and a non jelling agent such as Wildbens Enviroplug (if required bentonite pellets <br /> may be placed before the bentonite is tremmied, not to exceed 6 inched in thickness), <br /> • Have a cap composed of a minimum of 5 feet of neat cement, <br /> • Be dewatered by 2.5 horsepower 2-inch by 2-inch submersible pumps, capable of pumping <br /> approximately 40 gallons at 40 inches of head, and <br /> • Be plumbed directly to the holding tank in series and pumped individually using at least two <br /> extraction pumps at any time. <br /> configuration is in en e o p water ater ¢om the edges theimpacte zone into the center, for <br /> additional remediation of impacted groundwater using the "pump-and-treat' method. <br /> i <br /> I <br /> Page 1 of 1 <br />