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-8- <br />• <br />Additionally, we investigated the stability of the 8050 Pit and <br />reported it under our Job No. 5029. The observed angles of repose <br />ranged from 34 to 40 degrees for the loose dumped spoil. For pur- <br />poses of design we have selected a design value of 37 degrees. The <br />Canadian Pit Slope Manual reports typical values of the angle of <br />internal friction for shale to run on the order of 34 degrees, <br />for sandstones to range from 35 to 45 degrees. These values are <br />well within the range observed at the present time. <br />Cr~A~r4 ~~ <br />A large sample of the spoil from an existing mined area was <br />obtained to evaluate the gradation of future spoils. The test sample <br />• weighed about 400 pounds. Sizes larger than 12 inches were excluded <br />from the test sample. We believe the spoil rock will tend to <br />break down during handling and compaction. Based on observations <br />of fills constructed with the spoil for haul roads and other uses <br />at the current active mine area, we believe that about 30 to 40 per- <br />cent of the materials will be 12 inches or larger after compaction. <br />The minus 12-inch fraction of the spoil is, in our opinion, important <br />in determining the requirements for a transition zone between the <br />spoil and the fill drains. Gradation of the sample was as follows: <br />• <br />