Laserfiche WebLink
<br /> <br />4 <br />' 39°. Ttie dump is scheduled to be completed by the end of 1979. <br />According to Colowyo personnel, the placement procedure will <br />' consist of a series of 100-foot-thick end-dump lifts. Dozers <br />will be used to grade the lifts into the final design 3:1 slope <br />' configuration. Accordingly, a portion of each lift will be <br />reworked and placed in relatively thin lifts. <br /> <br />1 <br /> <br /> <br /> <br />1 <br />1 <br /> <br />1 <br />1 <br /> <br />1 <br />1 <br />1 <br />During our site visit on M14ay 22, we made tt~e following <br />observations: <br />1. The spoil consists of a well-graded silty sand and <br />gravel with cobbles and small boulders up to about 1 <br />cubic yard. The composition of tt~e particles include <br />siltstone, sandstone, and shale fragments. Figure 2 <br />shows the results of grain size tests on three-inch <br />samples of the fill. We estimate that approximately 30 <br />to 40 percent of the fill by weight exceeds 3 inches in <br />size. The results of three Atterberg limit tests on <br />decomposed shale fragments indicated a liquid limit of <br />about 40 percent and a plastic limit of about 20 <br />percent. This represents a silty clay of low to medium <br />plasticity. <br />2. Due to the natural sorting of end dumping, a three- to <br />six-foot thick zone of cobbles and boulders appears to <br />gave formed under each lift. This zone will probably <br />act as a drainage blanket and minimize tY~e potential <br />build up of seepage pressures within the fill. <br />3. The upper lift (Lift 2 in Figure 1) appears stable with <br />no signs of distress. A tension crack was observed in <br />the top of the lower lift (Lift 1 in Figure 1) at about <br />40 feet from the top of slope. According to Colowyo <br />personnel, these tension cracks probably developed when <br />fill was excavated from the toe of the slope in order <br />Lu cunsLrucL Ltle deLcnl.i.on d;un. <br />Golder Associates <br />