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Response to DRMS Michael Cunningham <br /> CEMEX Sandstone Quarry Division of Reclamation Mining and Safety <br /> The north-south trending fault noted by DRMS and observed on the geologic quadrangle USGS <br /> GQ-1629 (Braddock, et. al., 1988) does not transect any of the slope faces and is not anticipated <br /> to affect the slope stability. <br /> The rock mass shear strength stress relationship was modeled using the Mohr-Coulomb failure <br /> criterion. Engineering Analytics assumed uniform and homogenous rock mass conditions across <br /> the pit based upon the poorest pit wall conditions observed. The slope stability input parameters <br /> for the rock slope are friction angle (�) and cohesion (c). Friction angle and cohesion values <br /> were derived from published generalized Hoek-Brown parameters for the jointed rock mass <br /> criterion as outlined in equations 1 through 8 below (Hoek et al., 2002; Hoek 2007; Marinos and <br /> Hoek 2000): <br /> OF 1 6amb(s +mba3n)a-1 <br /> sin- 12(1 + a)(2 + a) + 6amb(s + mbQ3n)a-11 (1) <br /> C, _ uci[(1 + 2a)s + (1 — a)mbQ3n](S +mb�3n)a-1 <br /> )a-1 <br /> (1 + a)(2 + a) 1 + (6amb(s +mba3n <br /> (1 + a)(2 + a) <br /> Where: GSI — 100 <br /> mb = miexp C14D) (3) <br /> GSI — 100 <br /> s = exp (4) <br /> 9 - 3D <br /> a = 2 + 6(e-Gs1/15 _ e-20/3) (5) <br /> 63max <br /> 63n = 6ci (6) <br /> -0.91 <br /> 6 ax = 0.72(ac I (7) <br /> cm Y <br /> � — Q (mb + 4s — a(mb —8s))( Mb 4+s)a-1 <br /> Q (8) <br /> `"` " 2(1 + a)(2 + a) <br /> June 30, 2014 1 Engineering Analytics,Inc. <br />