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CESARE,INC. <br /> Recommended Minimum Factors of Safety for Slope Stability Analyses for Operations <br /> and Reclamation <br /> Generalized, Strength <br /> Assumed,or Measurements <br /> Type of Structure/Consequence of Failure Single Test Resulting from <br /> Strength Multiple Tests <br /> Measurements <br /> Non Critical Structures (e.g., fences) 1.3+ 1.25+ <br /> No imminent danger to human life, minor repair (1.15)` (1.1)' <br /> costs and minor environmental impact if slope fails. _ <br /> Critical Structures (e.g., residences, utilities, <br /> dams, pipelines, irrigation canals, public roads, etc.) <br /> Potential human safety risk, major environmental <br /> ' impact,and major repair costs if slope fails(includes 1.5+ 1.3+ <br /> environmental protection facilities (EPFs), such as <br /> tailings facilities, heap leach pads, process effluent <br /> ponds, milling facilities, overburden/waste rock <br /> storage facilities, and hazardous/toxic material <br /> storage facilities, etc. <br /> + Static Conditions <br /> ' Seismic Conditions <br /> Initial results indicated 1H to 1V slopes exhibit FSs less than 1 and would not meet DRMS guideline <br /> 1 FSs against failure. Remedial techniques would require massive toe berms or flattened slopes. <br /> Relatively steep slopes, like 1H to IV, require much stronger material than those proposed. Since the <br /> material being quarried is hard gneiss/granite, a viable alternative would be rockfill comprised of <br /> quarried bedrock material of large particle size. Historically, properly placed high quality quarried <br /> rock has been used to construct embankments over 100 feet high. <br /> Cesare understands the quarry will eventually envelope the haul road and the material from the haul <br /> road will be used for salable product. Cesare suggested moving the haul road alignment, such that <br /> parts of it would require excavating into the natural slope. The excavated bedrock material could be <br /> used for rockfill elsewhere along the alignment. The rockfill used for the haul road could be later <br /> used for the quarry's product. <br /> Al modified the haul road alignment to include excavating an upper portion of the alignment and <br /> moving other portions to flatter locations, making for more efficient fill placement.J&T provided three <br /> new sections for stability analysis, identified as Cases SS-1, SS-2, and SS-4. SS-2 is the uppermost <br /> fill reach and SS-1 and SS-4 are fill reaches lower down the mountainside. SS-3 is a section through <br /> an excavated slope that others will evaluate. A site plan showing the section locations is attached. <br /> 1 <br /> 20.075 Aggregate Industnes Haul Road Memorandum 05.14.20 2 <br />