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<br />No free water wi 11 be i n contact with the main embankment <br />during Phases I and II of the operation of the system. This <br />will aid in the desiccation and densification of the tailings <br />adjacent to the main embankment and provide support for the <br />Phase II raises. <br />Tailings deposition has been modeled in the laboratory <br />to predict tailings beach slopes. Data presented by Bentel <br />(1981) indicates that typical tailings will form a parabolic <br />block slope with a progressive decrease in slope from the <br />spigotting point to a relatively consistent beach angle. <br />Initially the rapid rate of rise will result in a flatter slope <br />than when the beach deposition is established. Based on the <br />results of laboratory testing, the beach following initial <br />operation of the tailings disposal area is expected to have <br />an average slope of one percent. <br />The length of the beach within the disposal area will <br />vary with time because of both the physical dimensions of the <br />area as a function of elevation, and changes in the deposition <br />pattern to control the location of the free water pool and the <br />surface expression of the disposal area. Beach lengths range <br />from 300 ft during the initial stages of Phase I deposition <br />to greater than 1000 ft during Phase II deposition in Year 7. <br />The projected tailings disposal area surface is shown <br />on Figures D.6-3 through D.6-8 for the 1/2, 1, 2, 4, 6, and <br />8 year points in the operation of the disposal area. <br />Deposition will be performed in panels similar to <br />segments of a circle. At any point in time, approximately one <br />half of the surface area of the disposal area will be under <br />deposition. Movement of deposition points will be performed <br />following the build up of a thin layer of tailings upon the <br />beach at the deposition location. <br />• <br />D-47 <br />