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• Note: The grid used to perform the search of the center of the cifcle with the weakest factor of <br />safety was selected to avoid the inside part of the embankment. Failure on this side would only <br />occur due to rapid drawdown which is not possible due to the type of principal spillway system <br />used in the pond. See pond design section of the permit. <br />The case runs of Appendix 1 show chat the grid search uses an increment of 2.0. Since the <br />factors of safety for all cases are well below the required factor of safety of 1.3, no additional <br />searches have been run using a lower increment, since there is no way the factor of safety <br />could be below the required amount. <br />6. Conclusions <br />Case 1 shows a scenario where the embankment has conservative strength parameters but <br />the foundation material has a conservative cohesion and friction angle but a slightly higher <br />density than that measured on the site. The safety factor of 2.19shows the good stability of the <br />pond dam. <br />• <br />Case 2 uses the most conservative values in the ranges given for both soil types from Table 1. <br />The results still show a factor of safety (1.73) well above the required amount of 1.3. This is <br />strong evidence that the ponds will not fail. <br />Case 3 uses parameters for both soil types which are far weaker than even the lowest values <br />from Table 1. This could be considered beyond worse case and the factor of safety (1.52) is <br />still significantly above the required limit. <br />Case 4 is the most likely case using middle of the road strength parameters from Table 1 and <br />densities measured from actual samples of the material. The safety factor of 1.95 is very good. <br />Note that no cohesion was used for the foundation material and it is possible that some <br />cohesion will exist here. The failure circle, center and radius for this case have been added to <br />Drawing 1 of this report. <br />Case 5 uses conservative strength parameters for both soils except a low cohesion value was <br />given to the foundation material assuming some clays will be present. The safety factor of 2.46 <br />shows that any cohesion in the foundation greatly increases the strength of the embankment, <br />. although it is not needed to pass the requirements. <br />(Revised 12/00) Attachment 2.05.3(3) -10-116 <br />