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Memo to Steve Renner <br />Fruits Highwall Stability <br />page 4 <br />1983 Analysis (Beach ~ Highwall) <br />As a portion of the proposed three lease permit revision, Bruce <br />Berends of Chen & Associates completed a stability analysis of the <br />Fruits portal area amended configuration in 1983. For conservancy, <br />Berends assumed fill material cohesion lower than those used by Geo <br />Testing in it's 1979 analysis. Chen's analysis use the simplified <br />Bishop method as modeled in the computer program Slope II. <br />Direct Shear Parameters: <br />Bedrock Material: <br />Fill Material: <br />Results of Analysis: <br />Portal Bench Fi11 <br />Angle of Internal Friction (8) = 27.0° <br />Cohesion (C) = 4,000 psf <br />Density = 135 pcf <br />Angle of Internal Friction (8} = 29.0° <br />Cohesion (C) = 750 psf <br />Density = 130 pcf <br />Facial Slope. Angle = 1.41h:iv (35.4°) <br />Static Factor of Safety = 1.3 <br />Portal Highwall <br />_ Static Factor of Safety = -1.4 -. - <br />Pseudo Static Acceleration Factor = 0.102 g <br />Pseudo Static Factor of Safety = 1.3 <br />1989 Aaalyais (Beach) <br />In 1989 the current Operator of the Fruits Mine, American Shield <br />Coal Company, proposed to lower the facial angle of the portal <br />bench in order to improve its stability for eventual reclamation. <br />A stability analysis was completed for the proposed reconfiguration <br />by Greg Lewicki. Mr. Lewicki recommended that the facial slope <br />angle be reduced from between 1.48h:1v (34°) and 1.23h:iv (39.9°)to <br />the lower slope of 2.Oh:ly (26.6°). Sainples.of the fill material <br />were collected and analyzed by Fox and Associates. Field density <br />was determined and the materials were sheared after compaction to <br />the observed field density. Based upon literature references by <br />Yang Huang, Mr. Lewicki adjusted the angle of internal friction <br />because 54 ~ of the sample proved to be greater than #4 sieve. <br />