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• Rule 6.5 <br /> GEOTECHNICAL STABILITY EXHIBIT <br /> JD-8 Mine Permit Amendment <br /> M-1984-014 <br /> 1. Based on the apparent stability of many older,unreclaimed waste rock piles in the <br /> immediate vicinity a detailed slope stability analysis was not performed. Many of these <br /> older mine waste rock piles have slopes as steep as 1.4H:1 V. The proposed final slope of <br /> the JD-8 waste rock embankment is 2H:1V. <br /> In the twenty seven years of working at the mine yard and lower mine waste area no <br /> surface springs or seeps have been noted. <br /> The stability of the proposed slopes is calculated using estimated material properties and <br /> the factor of safety calculation for cohesionless soils without seepage. The planned slope <br /> of the reclaimed JD-8 mine waste embankment is 26 degrees. The material will consist <br /> of blasted sandstone with an internal angle of friction of of approximately 34 degrees. <br /> Safety Factor=tangent of internal angle of friction/tangent of angle of material. <br /> Therefore <br /> Safety Factor=tan 34°/tan 26°_ .674/.500= 1.38 <br /> The calculated safety factor of 1.38 is within the 1.3 to 1.5 safety factor traditionally <br /> recommended for permanent slopes. <br /> • 4. The JD-8 mine has been an underground random room and pillar mine using <br /> appropriate blasting materials to advance the underground mining development drifts and <br /> to mine the ore in the mine. The mine workings are located approximately 600 feet <br /> below the top of Monogram Mesa. When blasting is done it usually consists of three or <br /> four headings/stopes consisting of approximately 100 pounds of explosives in each <br /> heading/stope. To date there has been no indication that any off-site areas have been <br /> adversely impacted by the blasting, and there is no indication that any areas should be <br /> adversely impacted by the limited blasting done in the mine. <br /> 1111 <br /> JD-8 Amendment Rule 6.5 <br />