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i <br /> Appendix B <br /> casing to ensure even distribution of filter material and grout within the borehole annulus. <br /> The well casing is thoroughly washed and/or steam cleaned, or may be purchased as pre- <br /> cleaned, prior to completion. <br /> f <br /> A filter pack of graded sand was placed in the annular space between the PVC casing and <br /> the borehole wall. Sand was added to the borehole through the hollow stem of the augers <br /> to provide a uniform filter pack around the casing and to stabilize the borehole. The sand <br /> pack was placed to a maximum of 2 feet above the screens, followed by a minimum <br /> 1-foot seal consisting of bentonite pellets. <br /> Cement grout containing 5 percent bentonite or concrete was placed above the bentonite <br /> seal to the ground surface. A concrete traffic-rated vault box was installed over the <br /> monitoring well(s). A watertight locking cap was installed over the top of the well <br /> casing. Reference elevations for each monitoring were surveyed. A traffic-rated vault it <br /> is typically set 112-inch above grade to minimize surface water from entering the vault. In <br /> areas that may be plowed for snow removal the vault is set flush with the surface to prevent <br /> damage to the vault by a snow plow. <br /> i <br /> i <br />