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February 27, 1997 -2- 963 -2178 <br />• hour. Rainfall depth for the 10 -year, 24 -hour storm event in the vicinity of the proposed <br />work was determined to be 1.90 inches [National Oceanic and Atmospheric Administration <br />(NOAA) Atlas 2, Precipitation - Frequency Atlas of the Western United States, Volume III - <br />Colorado, & Previous Reports]. <br />SedCAD+ soil input parameters unique to each site include Land Use Condition (LUC), <br />Curve Number (CN), Hydrograph Response Shape (HRS), Length of Overland Flow, <br />Control Practice Factor (CP), and acreage. Values for LUC, CN, HRS, Flow Length and <br />CP used in the analyses are presented in the following tables (reference SedCAD+ guide). <br />Acreages were calculated from base mapping and are included in the SedCAD + input/output <br />documentation. <br />TABLE 1 <br />LUC VALUES <br />• <br />TABLE 2 <br />CN VALUES <br />8 \61: \96 \2178\2178EM2.L7R Golder Associates <br />s <br />Undisturbed portions of the watershed, Oak <br />30% Oak -Aspen Cover Density <br />C8 <br />Cover <br />Undisturbed Portions of the Watershed, Pine <br />40% Pine Cover Density <br />71 <br />Cover <br />Fill slopes, bare (worst case), and vegetated <br />Developing Urban Area (No <br />91 <br />areas subject to disturbance by traffic <br />Vegetation) <br />Cut slopes, Soil Guard <br />An estimated value, between a <br />88 <br />classification of a Fully Developed <br />Urban Impervious Area of Dirt and <br />Gravel Street and Roads <br />Gravel hardstands and roads <br />Fully Developed Urban Areas, <br />89 <br />Impervious Areas, Streets and Roads, <br />Gravel, Hydrologic Soil Group C <br />8 \61: \96 \2178\2178EM2.L7R Golder Associates <br />s <br />