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<br />~~-slue <br />be required to achieve 90 percent of the expected consolidation in a 10-foot-thick layer of the impounded <br />tailings, assuming one-way drainage. <br />Due to the granular nature of the materials that are proposed to be used for construction of the <br />embankment, any consolidation within the embankment is expected to occur during construction. <br />' 4.2 Construction Materials <br />' In addition to evaluating the foundation conditions for the embankment raise, the material that will <br />be generated from excavation of the expanded tailings pond, and which is proposed to be used for <br />' construction of the embankment raise, was sampled to evaluate its engineering characteristics and suitability <br />for construction purposes. Laboratory testing was performed on material obtained from sample location S-4 <br />to determine grain size distribution. The results of the analyses indicate that this material is a silty, gravelly <br />' sand with 17 % passing the No. 200 sieve. The natural moisture content was determined [o be 13 %, based ) <br />on the average of the moisture contents for the fractions retained on and passing the No. 4 sieve. A Standard > <br />roctor test was performed to determine [he moisture-density relationship for the material. The results <br />indicate that the maximum dry density of this material is 125.3 lbs/ft', at an optimum moisture content of <br />CO%. Based on these results, it is apparent that it will not be necessary to add water to this material to <br />' achieve the optimum moisture content and optimal density during fill placement. Additional natural water <br />content determinations µ ill be made, in the field as construction progresses, to assess whether there is a need <br />for additional water or, alternately, if drying of the material may be necessary. This will be done as part of <br />' the initial quality control program. ~ <br />No potential borrow sources for clay material that might be used for a composite liner system were <br />' identified. Due to the geologic regime of the area, it is expected [hat a borrow source for clay is not available <br />within a reasonable haul distance. ~ <br />f ~-~ <br />t ~/ <br /> <br />1 <br /> <br />1 <br /> <br />1 <br />13 <br />