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10.2.11.1.2 Dry bentonite shall be added to the soil at <br /> the rate of 1 0 percent by weight, or approxi- <br /> mately 6 pounds per square foot of loose soil <br /> (6-inch layer) in the trench. <br />10.2.11.1.3 The bentonite shall be tilled into the loose <br /> soil until it is uniformly mixed and blended. <br />10.2.11.1.4 The layer shall be compacted to not less <br /> than 95 percent Standard Density using a <br /> vihratory plate or drum type roller. <br />10.2.11.1.5 The sequence will be repeated in this manner <br /> until the prescribed thickness of the soil seal <br /> has been reached. The surface of the previ- <br /> ously placed layer shall be scarified prior to <br /> the placement of the next layer. <br />10.2.11.1.6 Near structures that penetrate the clay barri- <br />er, a mixture of one part bentonite to three <br />parts soil (by volume) shall be dry blended, <br />applied, and hand compacted in the areas <br />that can not be reached by the mechanical <br />vibrator. <br />10.2.11.2 If the influx of groundwater is at a rate that blending <br />the bentonite/soil in the excavation is not practical, <br />or if the Contractor so chooses, the blending can be <br />performed in a large flat area by spreading a uniform <br />layer of locse soil, measuring and spreading the <br />appropriate weight of bentonite, rototilling the <br />mixture, and placing it into the trench or ditch in <br />bulk after the groundwater has been effectively <br />removed from the trench. The mixture shall then be <br />immediately compacted before groundwater can <br />infuse into the sealant. This procedure may have to <br />be repeated several times to attain an effective seal <br />while removing ground-water. <br />SPEC. A -EARTHWORK <br />PAGE 19 <br />