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H m i ib-lid cq(i <br /> Greg Lewicki And Associates, PLLC <br /> 3375 W. Pol%ers Circle Phone: (720)842-5321 Fax(303)346-693-1 <br /> Littleton,CO 80123 E-mail: info'r(lcsN icki.bir <br /> October 19, 2018 <br /> Elam Construction <br /> NOV 0 0 ;f <br /> 556 Struthers Ave <br /> Grand Junction, CO 81501 D'""``o o'PP,7'l 4%0n, <br /> Mining&Safety <br /> Orchard Grove Industrial Pit-Mining and Reclamation Slope Stability Analysis <br /> Elam Construction is mining and reclaiming a sand and gravel pit in Grand Junction, CO. The <br /> southeast slope of the planned pit is within 200' of structures owned by adjacent property <br /> owners. This slope stability analysis evaluated the proposed mining slope condition and the <br /> proposed reclamation slope condition. A diagram of the slopes analyzed,the failure circles, and <br /> the neighboring structures is attached as Figure 1. Also attached are the data logs and results <br /> images from the GALENA Software used. <br /> 1. Slope Stability Analysis <br /> The materials used in the analysis are sand and gravel, mixed grain size for the aggregate <br /> deposit, and loose sand, mixed grain size for the overburden. The material properties for these <br /> two materials are shown in the table below. They are from the SME Mining Reference <br /> Handbook(2002 edition)1. <br /> Table 1 —Material Properties <br /> Aggregate Overburden <br /> Description sand and gravel,mixed loose sand,mixed grain <br /> grain size size <br /> Unit Weight(lbs/ft3) 110 99 <br /> Friction angle(°) 45 34 <br /> Cohesion 0 0 <br /> The mining slope proposed at the 23.25 Pit is roughly 1 H:1 V at its extents. The first analysis <br /> evaluated this slope using Bishop's Method of Slices in the GALENA software. The results <br /> showed that the lowest factor of safety that produced a slope failure circle was 1.0. Failure <br /> circles that show very thin failures along the surface of the slope are not considered in this <br /> analysis, as such circles do not show a fundamental failure of the overall slope. <br /> The reclamation slope is proposed to be 3H:1 V. It will be created by backfilling the mining slope <br /> with overburden and broken pieces of waste concrete. This mixture is similar in form to the <br /> source aggregate, being a mixture of sand and pieces of competent rock from the concrete. <br /> Therefore, the sand and gravel, mixed grain size material type is used to represent the backfill. <br /> 1 Table 2.5;Originally from Houk and Bray, 1977 <br /> Orchard Grove Slope Stability 1 X creg tswicki and Associates.MIA' <br />