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• 2. SEDCAD+ INPUT PARAMETERS COMMON TO ALL <br />ANALYSES <br />• <br />lJ <br />2.1 Storm Type <br />The Storm Type was selected as SCS Type II. The SEDCAD+ model (hydrograph convolution interval) time <br />increment was selected as 0.1 hour. <br />2.2 Soil Type <br />The site is located within Soil Mapping Unit Number 31 (Permit). The soil type is representative of the Holderness, <br />Morop, Absazokee, and Work Series, among other similaz soils (Permit). SEDCAD+ soil input parameters include <br />(Soils of Colorado, Loss Factors and Erodibility Hydrologic Groupings, 1983, Soil Conservation Service) K (a <br />measure of susceptibility of soil particles to detachment and transport by rainfall and runoff) soil erodibili[y = 0.32, <br />and a hydrologic group of C. There is a lazge fraction of cobble size material in the colluvium of the site. For <br />the purposes of the SEDCAD+ analysis, the "erodible portion" of the material is classified as a clay loam soil. <br />A "type" particle distribution of the "erodible fraction", presented in the following table, is used in this analysis. <br />Table 2.2-1 Panicle Size Distribution <br />Screen Sizes in rnm Percent of Eroded Panicle Size Fraction Passing <br />4.00 100 <br />2.00 99 <br />1.00 90 <br />0.500 88 <br />0.250 85 <br />0.125 82 <br />0.063 74 <br />0.016 56 <br />0.004 38 <br />0.0001 0 <br />2.3 Vegetation <br />The vegetation of the site is primarily oak brush with chokecherry and serviceberry. There is a good layer <br />(minimum of 2 inches) of brush litter on the ground. There is a small patch of Pinion -Oak in the azea. <br />(West Elk Lone Pine Gulch Development Waste Pile SAE, 12 Octobcr 1995, Page 3 of 7) <br />