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• ~,;j, ~`~ GRAND J[JNCTION <br /> ,lr; LINCOLN DeVORE, Inc. <br /> f'-i"~ GEOTECFINICAL ENGINEERS -GEOLOGISTS <br /> ]441 Motor Street <br /> Grand Junction, CO. 81505 <br />Fax: (970) 242-1561 <br />E-mail: www.g7dem(tr~,eatthlink.net <br />August 11, 2004 <br />Mr. Jeffrey Dubbert <br />Blue Mountain Energy Inc. <br />Deserado Mine <br />PO Box 1067 <br />Rangley, CO 81648 <br />Re: Final Slope Stability Calculations Coal Refuse Area # 2, #3 & #4, <br />Increased Height & Slope Steepening, Deserado Mine, Utah <br />At your re<(uest a slope stability analysis of the proposed waste pile slope modification has been performed <br />by personnel of Grand Junction Lincoln DeVore. This analysis included auger borings and sampling of the <br />existing Coal Refuse Pile. Blue Mountain Energy proposes to increase the pile height by 30 feet or more <br />and to steepen the final slope face up to 1:3 (vertical:horizomal): Our computations were made to model <br />the fill height up to 100 feet and the final slope surface was `benched'. Following aze our findings. <br />• The original profile of the existing natural foundation soilslweathered formation and the proposed surface <br />of the combined refuse areas # 2, # 3 & #4 were taken from a map prepared by Blue Mountain Energy <br />Inc., 1997. This basic information was used for our previous report prepared I-5-98. The slope'stabitity <br />calculations utilized the computer program SlopelW, Ver. 5.10; Geo-Slope. The analysis was performed <br />using Morgenstern-Price method of slices, with the lmalf-sine function of time Slice Side Function. ;The slip <br />surfaces were defined using the Grid and Radius option. A tension otack at the failure `head' was;modeled <br />with a 135 ° intercept angle specified. The Grid and'Radius were positioned for the `optiimmm' and most <br />conservative Factor of Safety (FOS). The Grid and Radius settings produce 605 possible trial sutl'aces per <br />model positioning. <br />The refuse properties are based upon triaxial and direct sheaz strength test of samples collected by and <br />delivered to Lincoln DeVore and Grand Junction Lincoln DeVore since 1985. The bedrock properties <br />(Chen & Assoc J were provided to Lincoln DeVore by the client, in 1985. <br /> <br />For our presed slope stability calculations, the most recent shear strength testing of the waste coal was <br />utilized. This sample was obtained during ow drill program.on the Refuse Pile, 4-04. The selected sample <br />was remolded in a saturated condition, consohdated andthen-sheared. The actual sample shear sequence <br />was, to shear the specimen (2.5" dia) to 0.03 inches strain, a reverse sheaz cycle and recd to the original <br />position. The sample was unloaded, reconsolidated, resheared ,reversed sheared and reset for eacJm normal <br />stress (450, 1025, 1549, 2050, 3100 and 4100 psf-. Testmetimod'is similar (but without pore pressure <br />measuremerts) to that described in Gan, Fredlund & Rajardjo;1988, Ddemmination of the Shear;Strength <br />Parameters of an Unsaturated Sod Using the Direct Sheaz Test, Canadian Geotechnical Joural.:The sheaz <br />testing was accomplished with a test rate of 0.0014 inches/min. (Plus or minus). The test machine is a <br />Geocomp Corp. Sheaz Trac II, with automatic data acquisition and preliminary data reduction (Geocomp <br />PC Progranm, SHEAR, V. 1.0.2.92). <br /> <br />