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iii iiiiiiiiiiiu iii ~ <br />.._ <br />~ ~ - ':: GRAND JUNCTION <br />~.~ ~ LINCOLN DeVORE, Inc. <br />_ GEOTECHNICAL ENGRJEERS -GEOLOGISTS <br />144 f Motor Street <br />Grand Junction, CO. 81505 <br />Received <br />BALAZ & ASSOCIATES <br />loos North I2~ street MAR 2 "~ 2001 <br />Grand Junction, Colorado 8150s <br />Durango Fiekl Office <br />Division of Minerals 8 Geology <br />Re: Slope Stability Computations, Proposed Cross Sections <br />The Gallegos Corporation, Conger Harvesting Area, Marble, CO. <br />q ~/~ <br />~' ~~ <br />Mar h~zlbq~00~ ~~ <br />d~+°~l <br />°`„ <br />Tel: (970) 242-8968 <br />Fax: (970) 242-1561 <br />E-mail www.gjldem@gj.net <br />r•.,-~ <br />`1 ;-. <br />~;._._.~_ "8 <br />'-' ~ - ' ,`ifP~0. <br />..,! t ~: <br />-41 <br />At the request of Mr. Bill Balaz, Edward M. Morris, P.E. of Grand ]unction Lincoln DeVore, Inc. Has <br />performed computations of the proposed Working and the Reclaimed slopes of the above referenced project. The proposed <br />Cross Sections were taken from Exhibit CS-I, BALAZ & ASSOCIATES, 2/l0/Ol. These computations are to supercede <br />previous computations which were based upon preliminary extraction plans. <br />Slope stability calculations were performed on the proposed Working and Reclaimed Slopes. The stability <br />analysis addressed the individual extraction slopes, which are believed to be the `Critical' Slopes. The previous Grand <br />]unction Lincntn DeVore, Inc. computations are believed to adequately address the `global' condition of the entre <br />embankment. 1'he analysis was performed using the PC software SLOPE/W, Version 4, Geo-Slope International L i D, <br />Calgary, Alberta, Canada. The analysis utilized the Limit Equilibrium Theory for the factor of safety, incorporating 4 <br />methods. <br />Fellenius or Ordinary Method = Moment Equilibrium <br />Bishop Simplified Method = Moment Equilibrium <br />Janbu Simplified Method = Force Equilibrium <br />Morgenstem-Price Method = Moment and Force Equilibrium <br />No seismic coefficient was assumed in these calculations. The Talus Material m the slopes are assumed <br />to be very moist to nearly saturated and the Water Table is assumed to be present throughout the entire slope. <br />The analysis indicated the Reclaimed Slopes have a sufficient factor of safety, equal to or greater than 1.5, assuming the <br />Sections presented in Exhibit CS-l, BALAZ & ASSOCIATES, ?/l0/01 are followed Figures I, II & III present this model <br />with the final Reclaimed Slopes. <br />Based on slope stability calculations, the maximum extraction slope [l:l (horizontal to vertical)] which can be utilized is <br />30 feet high, with the natural slope remaining above the extraction face [max. slope 2:1 (horizontal to vertical)]. The face <br />will have a Safety Factor (S.F.) of 1.27 (Fellenius or Ordinary Method) to 1.50 (Morgenstern-Price Method). Minor <br />sloughing on the extraction face may occur. <br />