Laserfiche WebLink
For the purpose of a conservative geotechnical analysis of the backfill's slope stability, cohesion <br />will be ignored. Therefore, the slope stability can be evaluated by comparing the slope angle to <br />the internal angle of friction of the material. For GC material this is 31 ° or greater. <br />Safety Factor = tangent of internal angle of friction <br />tangent of the actual slope <br />tan(31 °) <br />Safety Factor = tan(18.4 °) <br />Safety Factor = 1.81 <br />The backfilled slope is located significant distance from the ground water table, and any <br />structures that may be damaged by a slope failure. Additionally, the backfill material in question <br />has been shown to be stable in stockpiles with slopes of 1.8H:1 V for years at a time. Therefore, <br />the minimum Safety Factor for the backfill slope is 1.3. The analysis above shows that the slope <br />has a Safety Factor of 1.8, well in excess of the minimum. The backfill slope, as designed, is <br />safe. <br />The north property backfill will be installed in lifts of no more than 18 inches in thickness, to a <br />compaction standard of 90% of maximum dry density. This compaction standard is easily <br />achieved by dozer and other equipment driving across the lifts following placement. Compaction <br />will be checked a minimum of once per lift. <br />Ralston Quarry, April 2015 U -4 <br />