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D <br />rage 5 <br />Tom Gillis <br />Ffarch 12, 1981 <br /> <br />type analyser; are reconrtnended, Sensitivity analyses assume variation in <br />material properties and degrcos of saturation in order to determine the <br />eCfr_ct inar_curacy in these assumptions would have upon the calculated <br />slope factor.; of safety. Reclaimed s.Iopes are required to achieve a static <br />slope factor n` safety of at least 1.3 (Rule 9.27.3(3)]. <br />Colorado Westmoreland's amended application for the Orchard Valley mine <br />includes a simplistic stability analysis of the proposed final reclamation <br />scheme utilizing the "Culmann method". The "Culmar'u7 method" is an analytical <br />procedure for determining the safety factor of a uniform soil slope which <br />assumes that the failure surface is planar in steep slope embankments. <br />Considering the extensive slope stal+ility hazard characteristic of the Orchard <br />Valley mine site, the inhomugc•neous nature of the bedrock and f.i11 materials, <br />and the slope of the mine site, an analysis utilizing the "Culmann method" is <br />inappropriate for the Orchard Valley permit area and does not satisfy the <br />requirements of the Colorado permanent regulatory program, <br />Furthermore, the stability analyses contained within the amended application <br />are based ulnn an assumption of shear strength derived by correlation with <br />one penetration test performed by Fox and Associates during an augering <br />project near the truck loadout. This conversion technique is extremely <br />crude, The +naturials tested may not be representative of the materials <br />existing beneath the entire mine site. The assumed property is utilized for <br />bedrock, colluvi.um and fill materials assuming that all these materials <br />are uniform. This assumption is unfounded, <br />Conclusion <br />Colorado fvestmoreland, Znc.'s proposed reclaimed configuration for the <br />Orchard Valley mine site is inadequately supported within the amended application. <br />CWZ must complete an appropriate 9eotechnicaI analysis of the proposed final <br />configuration. The results of that investigation must then be used to produce <br />a detailed engineering design which conforms with the requirements of the <br />appropriate sections of the Colorado permanent regulatory program. Thorough <br />mathematical stability analyses, wl~iclr properly model the proposed cut and <br />fill benches of the final reclaimed configuration, must then be completed to <br />demonstrate con Cormance with the required static slope factor of safety <br />reguirement of ,i.3. <br />~~~ ~ V <br />