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ditches, and Culverts, A copy of the computer program's input and output file information <br /> has bebn inclVded in each sedimentation pond design report. <br />the input includ¢s precipitation amount (inche3), xatershed area (acres), tim¢ of <br />dortcentratian Chourg), runoff Curve ~ number (CN), representativo particle-site <br />distributions of the soil types in the xatesshed, Sedi mentolo9y lhf orraetion, and spillway <br />f of osmotion, btc. <br />Yhd prpcipi tation amounts for the YAest Mine for the dosi9n storm durotions were abtainpd <br />from the NDAA Precipitation Frequency Atlas Pr et+air ti n - Fre„ie cv ptl as of the T7estern <br />St tes Volume ll[ ~ Colorado, 1973, end are listed below: <br />10-Year, 24-hour - 1.70 inches <br />25-Year, 24-hour - 2.10 inches <br />100-ydar, 24-hour - 2.50 inches <br />These amounts also include xat of emanating from Snow cover a3 snbwmelt in 0 limited <br />period of time. <br />The runoff curve Number (CN) Ss a factor relating <he amount bf rai of ell to the amount of <br />runoff far a giveh area. Thp soil prodibility factor ("k" factor) is a factor of a soils <br />susceptibiliLY to erasion antl infil?ration capacity, Th esb factors are dependent Upon the <br />inTiltratlon characteristics of the soil tYPes and the type and amount of vegetdtioh, <br />iahles t3~1 end 13-2 list the val ueS of CN and "k" for different soils types at the Yoast <br />Mihe. <br />The Cif and ~k`• factor for bath of the ponds is bet eYmined as h weighted average. The <br />undisturbed area curve number and ~`%" {actor information is based vh the veg et etion and <br />soils information found within Tabs 9 end 10, respectively, ofi the Yoast Mine permit, <br />The sediment storage is calculated using the Revised Universal Soil loss EgVation <br />contained within contained within the SEDCAD Computer program, The Spillways are <br />i <br />designed using the spillway routing subroutine program in the SEDCAD computer program and <br />applicable enginoerih9 procedures as tlescribed ih the text of each sedimentation pond <br />design report. <br /> All sediment ponds are designed and lot dted to capture surf ale runoff from upstream <br /> disturbance of ea5 antl t0 comply with all applicable Stdte and federal regulations. <br />Designs for the following setlimenTation ponds are provided in this tab: <br />7 Revised 05/$3/95 <br />