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STATE OF COLORADO <br />DIVISION MINERALS AND GEOLOGY <br />Department of f Natural Resources <br />1313 Sherman St., Room 215 <br />DIVISION OF <br />Denver, Colorado 80203 ' <br />Phone: (303) 866-3567 MINERALS <br />FAX: (303) 832-8106 -& <br /> GEOLOGY <br /> RECLAMATION <br />DATE: March 12, 2003 MINING-SAFETY <br /> <br />TO: <br />Peter Wayland, Weiland Sugnet, Inc. Bill Owens <br />Governor <br /> Greg E. Walther <br /> <br />FROM: <br />Allen Sorenson - Executive Director <br /> ? Ronald W. Cattany <br /> Division Director <br />RE: Suggested Conservative Soil Shear Strength Parameters for Stability Analyses <br />Given that these strength values, in particular the residual strength value for the weathered bedrock, <br />represent the worst-case for potential slope instability, any safety factor in excess of one should be <br />protective of critical structures. <br />CLAY, sandy, soft to stiff, very moist to wet, brown (CL): <br />o' = 28 degrees c' 50 psf moist unit weight = 114 pcf saturated unit weight = 126 pcf <br />SAND, fine grained, clayey, silty, very loose, very moist to wet, brown (SC, SM): <br />o' = 2 degrees c' = 10 psf moist unit weight = 90 pcf saturated unit weight = 115 pcf <br />SAND, fine grained, clean to slightly silty, dense, wet, brown (SP, SP-SM): <br />o' = 31 degrees c' = 0 psf moist unit weight = 117 pcf saturated unit weight = 130 pcf <br />SAND & GRAVEL, fine to coarse grained, some cobbles, clean to slightly silty, very dense, wet <br />brown (SP, GP): <br />o' = 35 degrees c' = 0 psf moist unit weight = 130 pcf saturated unit weight = 137 pcf <br />WEATHERED SHALE, this is an over-consolidated stiff-fissured clay, so the residual strength <br />values are appropriate to the;analysis: <br />o' = 14 degrees c' 0 psf moist unit weight = 125 pcf saturated unit weight = 142 pcf <br />c:\acs\My Documentslshear strength paranieters.doc