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~l <br />• ) <br /> <br />sub-classifications were made in each category as shown in <br />Table 2. <br />The cover type (and the tributary drainage area) for some <br />structures will vary throughout the life of the structure as <br />mining and subsequent reclamation occurs. For these cases, <br />the anticipated worst condition is assumed for the, hydrologic <br />analysis. <br />2. Percent Vegetation Cover - The percent of ground surface <br />covered by vegetation in undisturbed areas was estimated from <br />field inspections and aerial photographs. <br />3. Hydrologic Condition - The hydrologic condition was directly <br />related to the percent vegetation cover as shown in Table 2. <br />4. Hydrologic Soil Type - Soil survey maps, as contained in Tab 9 <br />of the current Mine Plan, provides the basis of determining <br />the hydrologic soil type and soil erodibility factor, "k" <br />factor (see Table 3). <br />TABLE 2 <br />SCS Curve Numbers <br />for <br />Nucla Mine <br />Montrose County, Colorado <br />Undisturbed Areas <br />Cultivated Land <br />(Small Grain) <br />Rotation Meadow <br />(Contoured) <br />Meadow (Riparian) <br />Pasture or Range <br />Juniper - Grass <br />Upland Sagebrush - Grass <br />Hydrologic <br />rologic Soil Group <br />Poor 76 84 88 <br />Good 75 83 87 <br />Poor 75 83 85 <br />Good 69 78 83 <br />Good 58 71 78 <br />Poor 79 86 89 <br />Fair 69 79 84 <br />Good 61 74 80 <br />Poor 75 85 89 <br />Fair 58 73 80 <br />Poor 67 80 85 <br />Fair 51 63 70 <br />4 <br />