Laserfiche WebLink
The Factor of Safety (FOS) for gravel with a 3H:1V slope, which is 18.26 degrees in GC <br />classified material with an assumed internal angle of friction of 34 degrees can be approximated <br />by ignoring the cohesion component of the stability, and simply evaluating the internal angle of <br />friction as follows: <br />FOS = <br />FOS = <br />This factor of safety far exceeds the normal long term safety factor of 1.3, therefore the plan of <br />extraction as presented is acceptable. <br />I, Greg Lewicki, P.E., with over 28 years of experience in mine slope safety analysis in <br />Colorado, certify that the mine plan and reclamation plan presented in this application will lead <br />to stable slopes during and after mining and that there is no realistic threat of failure or to the <br />stability of any structures outside of the permit area. <br />Tangent of Actual Angle of Failure Surface <br />Tan 34° .6745 <br />= = 2.04 <br />Tan 18.3° .333 <br />Tangent of Internal Angle of Friction <br />Greg Lewicki, P.E. <br />P.E.# 20335 <br />Date: <br />Uncompahgre Pit, February 2013 U - <br />