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~~ • • <br /> <br />2. Rock fill material averaging. <br />o In addition, the report proposes that the sampling <br />content was representative of the pile since 54$ of the <br />material was larger than the No.4 sieve and should be <br />countered balanced by "the inner depths of the pile that <br />contain a greater amount of fines". If this assumption <br />were to hold true, then the rock fill material sampled at <br />a depth of 2.5 feet should already be averaged. Why then <br />do the researchers re-average the pile material a second <br />time and increase the Phi from 37 degrees to 41? <br />Conclusion: <br />These two assumptions lead me to conclude that a lower angle of <br />friction is more realistic and that Case 4 and 5 on test printout <br />(pg 116) should be the cases most likely to represent the situation <br />of the Fruita #1 rock fill. Under these scenarios, a 1.65 factor <br />of safety would be obtained. Though lower than the 1.773, the fill <br />would still be within the regulatory 1.5 and in compliance, <br />although the probability of slope failure is higher. <br />In addition, slope stability of the rock fill has increased due to <br />the fill reconfiguration of the pile in 1990. <br />Reconfiguration of the pile entailed an entire widening of the <br />pile's breadth from elevation 5800 feet to 5630 feet, with the one <br />exception of the area along contour interval 5760 where topography <br />prevented widening due to a narrowing of the valley sides. In <br />addition, the rock fill was extended from 5640 feet down to 5625 <br />feet, a total of 15 feet to be added length-wise. Both <br />modifications of widening and lengthening the pile will only <br />reinforce the pile's stability, since the slope would be lessened, <br />resulting in a grade of 2(H):1(V). <br />Recommendation: <br />Therefore, it is my recommendation to approve the proposed rock <br />fill and embankment reconfiguration, with the condition that the <br />factor of safety be lowered to 1.65 using a Phi of 39 degrees. <br />In addition, I concur with the report that the diversion ditch <br />remain in place to prevent saturation of the pile's surface or <br />initiate a seepage condition within the pile. <br />Thank you for the opportunity to exercise my technical muscles. <br />SES <br />SBfruita <br />