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Section 3K 2012 vu�wacn.s • Casing Diameter—Nominal 2 inches. • Casing Materials—ASTM F480 Schedule 40 PVC. The well casing shall be plugged with a threaded cap to prevent sediment or rock from entering the well. The casing shall be mechanically joined in a manner that ensures its watertightness. Organic solvent cements or glues shall not be used for joining PVC casing • Well screen —Factory slotted ASTM F480 Schedule 40 PVC. The screen shall not exceed 15 linear feet, unless site conditions dictate otherwise, and will be placed at a depth as determined in the field. • Filter Pack — The filter pack will be comprised of #2/12 (12x20 mesh) Monterey Silica Sand, or equivalent. The proposed monitoring well is intended for sensitive water quality determinations; therefore all filter pack material will be handled in such a way as to avoid contact with contaminants. The filter pack will be extended approximately two-feet above the top of the screen. • Slot Aperture Width — Well screens will be installed with 0.020 inch aperture width. The gradation is based on the initial selection of the filter pack and is sized to retain the D90 of the filter pack. • Transition Seal —1 to 5 feet of granular Bentonite will be placed between the filter pack and cement based surface seal. Potable water shall be added to the Bentonite transition seal prior to the placement of neat cement-based sealing materials. • Surface Seal — Neat cement grout shall be mixed at a ratio of one 94-pound sack of Portland cement to 5-10 gallons of potable water. It shall be placed from the top of the transition seal to land surface. Drilling fluid or cuttings from drilling shall not be used in sealing material. Cement-Bentonite grout shall not contain more than 3-5% Bentonite. The seal must extend to at least 20 feet below the ground surface. • Protective Surface Casing — An at-grade traffic rated Christy box, surrounded by a concrete apron designed to shed water away from the well will be constructed to protect the well site. 9 City of Riverbank Waste Water Treatment Facility Background Water Quality Monitoring Well Work Plan