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• Diversion Ditches <br />The soil type for the area is Dollard, soil type C. <br />During 1992 a vegetation study was performed at the mine <br />site and adjacent areas. The vegetation study presented in <br />Voume II included a study of an extended reference area <br />north (above) the county road. The results of the vegetation <br />study are as follows: <br />Extended Reference Area <br />------------------------------------------------------ <br />------------------------------------------------------ <br />Cover 46.93 <br />Shrubs - Relative Cover 65.93 <br />Gambel Oak - Relative Cover 42.0$ <br />Trees - Relative Cover 24.4$ <br />Juniper - Relative Cover 13.03 <br />Perennial Grasses - Relative Cover 3.9% <br />Perennial forbs - Relative Cover 4.33 <br />Other - Relative Cover 1.53 <br />The run-off curve number for the extended reference area <br />is taken from Table 2-2d - Run-off curve numbers for arid <br />and semi-arid rangelands. <br />Semiarid Rangelands <br />Cover type Condition Curve # <br />---------------------------------------------------- <br />---------------------------------------------------- <br />• Oak-aspen poor <303 74 <br />Oak-aspen fair 303-703 57 <br />Average Curve Number 66 <br />Based upon a review of the mine area vegetation map D-3-16 <br />and field observations, it can be seen that the drainage <br />area above the refuse pile is well vegetated with the oak- <br />aspen vegetation type. This area does not have exposed rock <br />outcrops. For these reasons, drainage areas 3A, 3B & 4 will be <br />assigned a curve number of 66. <br />An average of the poor and fair ground cover condition <br />was used in order to recognize that some of the drainage area <br />may have sparse vegetative cover. <br />The remaining drainage areas will be assigned curve numbers <br />based upon the Oak-aspen vegetation type with poor cover <br />in order to recognize that these areas contain both fair <br />ground cover and areas of rock outcrop. The curve numbers <br />to be used in the run-off calculations are summarized as <br />follows: <br /> <br />4-B:5 October 1994 <br />