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9. A minimum three-foot thick bentonite seal is placed directly on top of the sand pack. In <br /> dry conditions the bentonite shall be granular type of 8-30 mesh gradation. In wet or <br /> saturated conditions the bentonite shall be in 114-inch pellets. Depending on site <br /> conditions, the bentonite may have to be tremied into place. After placing the bentonite, <br /> one gallon of potable water shall be added for every two pounds of bentonite and a <br /> minimum of thirty minutes shall be allowed for hydration of the bentonite seal. <br /> In Riverside County, as required by the Department of Health, bentonite is premixed with water <br /> on the surface and placed in the annulus above the filter pack in wet form. <br /> 10. A grout seal is placed in the remaining portion of the annular space above the bentonite <br /> seal to the ground surface. The grout seal consists of a cement or bentonitelcement mix <br /> and is placed utilizing the tremae method for cement grouts. When using a hollow-stem <br /> auger, the auger can function as a tremae. This is done by filling the auger with grout and <br /> then pulling augers in sections. As each section is removed the augers are refilled with <br /> grout until all the hollow-stem augers have been removed. <br /> 11. All groundwater monitoring wells must be appropriately developed until the discharge <br /> water contains less than 10 ppm settleable solids, <br /> a, <br />