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`~~ ESTIPIATE OF RUNOFF <br />PROPOSED ^tIIII'1G SITE - IJELD COUNTY, COLORADO <br />SITE CHARACTERISTICS <br />The watershed considered for this runoff estimate is outlined, along <br />with the approximate limits of mining, in Figure 1. The line designated <br />as "watershed boundary" is the boundary of the catchment area that will <br />potentially produce runoff originating on or passing throunh the proposed <br />mining area. As such, the watershed includes a small area upslope from <br />the proposed mining area, the potential runoff from which will pass through <br />the mining area unless diversions are constructed. The downslope boundary <br />of the watershed is the downslope boundary of the proposed mining area. <br />The general slope of the watershed is toward the northeast at an <br />t• average value of about 1.5 percent. Locally, the general slope is broken <br />by numerous small mounds and closed depressions formed by wind erosion. <br />There are no well-defined drainage channels that collect runoff from a <br />significant area. In other words, there are no "drainage points" in the <br />sense that locations where retention structures would obviously collect <br />water cannot be identified. In fact, there is no evidence of surface <br />runoff occurrence ;~ithin the watershed boundary shown in Figure 1. Tlie <br />infiltration capacity of the deep, well-drained sands that mantle the <br />area is, apparently, sufficient to prevent runoff. Prevention of runoff <br />is further aided by the relatively great surface storage provided by the <br />numerous closed depressions in the sand. <br />The surface soils in the area consist chiefly of deep, well-drained <br />sands with a high infiltration capacity. The land is currently used for <br />pasture and is only intermittently grazed. <br />