Laserfiche WebLink
1 <br />'• <br />1 <br /> <br /> <br />1 <br /> <br />1 <br /> <br /> <br />1 <br /> <br /> <br />SubTerra, Inc. Twentymile Coal Company 5/23/99 <br />Northern Mining District Rockfall Hazards Evaluation <br />Table 2-2: Surface Descriptions for Tangential Coefficient Selection <br />CRSP3 Description Equivalent Site Condition <br />Smooth hard surfaces such as pavement or <br />smooth bedrock surfaces <br />Most bedrock surfaces and talus without Sandstone cliff face; road pavement <br />vegetation <br />Most talus slopes with some low vegetation Talus covered upper foreslope; thin colluvium <br /> over marine shales on upper foreslope. <br />Vegetated talus slopes and soil slopes with Thin colluvium overlying marine shales on <br />scarce vegetation upper foreslope; colluvium covered lower <br /> foreslope <br />Brush covered soil slope Colluvium covered lower foreslope. <br />Table 2-3: Surface Descriptions for Restitution Coefficient Selection <br />CRSP3 Description Equivalent Site Condition <br />Smooth hard surfaces and paving <br />Most bedrock and boulder fields Sandstone cliff face; road pavement <br />Talus and firm soil slopes Talus covered upper foreslope; thin colluvium <br />over marine shales on upper foreslope. <br />Soft soil slopes Colluvium covered lower foreslope. <br />Table 2.4: CRSP3 Parameter Ranges for Representative Site Conditions <br />J <br />~~ <br /> <br />1 <br />'• <br />1 <br />SITE CONDITION Tangential <br />Coefficient Restitution Coefficient <br /> Min Ave Max Min Ave Max <br />Sandstone Cliff Face 0.83 0.85 0.87 0.33 0.35 0.37 <br />Road Pavement 0.83 0.85 0.87 0.33 0.35 0.37 <br />Tallus Covered Upper Foreslope 0.82 0.835 0.85 0.30 0.315 0.33 <br />Thin Colluvium Overlying Marine <br />Shales on Upper Foreslope 0.80 0.835 0.85 0.30 0.315 0.33 <br />Colluvium Covered Lower Foreslope 0.78 0.805 0.83 0.28 0.29 0.30 <br />5 <br />PN:9915 <br />