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Response to DRMS Michael Cunningham <br /> CEMEX Sandstone Quarry Division of Reclamation Mining and Safety <br /> Parameter Description Value Used Justification Reference <br /> m, Material Constant 13 Lowest end of the range for Hoek(2007) <br /> Sandstone <br /> This value is for <br /> B locky/Disturbed/Seamy <br /> GSI Geological 40 rock with Smooth Altered Hoek(2007) <br /> Strength Index surfaces, which is <br /> conservative for the <br /> observed pit walls <br /> Disturbance Modest damage with small <br /> D Factor 0.7 scale blasting. Typical Hoek(2002) <br /> values range from 0-1.0 <br /> H Max Slope Height 138 ft Proposed Final Pit Layout - <br /> Uniaxial 400'000 psf Lowest strength value <br /> 6ci Compressive provided in the table for West(1995) <br /> Strength (2,800 psi) intact sandstone <br /> y Unit Weight 140 pcf Average value for Rock - <br /> Engineering Analytics updated our strength values and slope stability analyses based on the <br /> revised input parameters provided above. The input parameters were revised to be more <br /> conservative. This resulted in an updated friction angle of 35.5° and cohesion of 3,400 psf. <br /> Input parameters used to calculate the Mohr-Coulomb failure criterion are conservative based on <br /> the visual observations of the pit walls and conversations with CEMEX about observed geology <br /> observed in the pit during excavation. <br /> 2. DRMS Comment: "Figures 4 and 5 show the cross section A-A' that was analyzed for <br /> stability. The cross section for Figures 4 and 5 is approximately 2100 feet long and does not <br /> match the cross section shown on Figure 3 (approximately 120 feet long). Please revise Figure 3 <br /> to reflect the entire cross section that was analyzed. " <br /> EA Response: The cross-sections length and scale has been revised on Figure 3 <br /> 3. DRMS Comment: "Please indicate on Figures 4 and 5 where the affected area boundary <br /> lies". <br /> EA Response: Revised Figures 4 and 5 attached show the affected area boundary lines. <br /> 4. DRMS Comment: "Please verify that the slope will remain dry and that the seasonally high <br /> groundwater level is below the pit floor". <br /> EA Response: There are ten CEMEX monitoring wells located approximately 1.5 miles <br /> southeast from the Sandstone Quarry as shown in Figure 6. These wells have been monitored <br /> June 30, 2014 1 Engineering Analytics,Inc. <br />