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Figure 2.0. This160 acre azea represents the hydraulic watershed upslope of the mine <br />roads and benches. Because the mine and upslope area occurs within terrain of variable <br />' topographic relief, storm runoff is to be managed within a number of individual subbasins <br />and several drainage control structures on the mine site. Plate 1.0 shows 15 discrete <br />drainage areas or subbasins that comprise the mine and upslope areas. Table 1.0 shows <br />' each subbasin's characteristic parameters (acreage, slope, etc.) as determined by map <br />measurements. <br />The main objective of the routing plan is to control storm runoff that originates on <br />upgradient azeas, mine benches, and roads such that high-energy runoff does not cause <br />extensive erosion of these and downslope areas including faces of mine dumps, and <br />outslopes below road cuts. Protection of the dump faces and outslopes is necessary to <br />meet revegetation goals in accordance with the Reclamation Plan. The schematic <br />drainage plan meeting the stormwater control objective is shown in Figure 3.0. <br />Each of the delineated subbasins has the potential to contribute runoff to a specific mine <br />drainage structure or structures. An effort was made to design structures that convey <br />stormwater runoff with minimal recontouring or grading of the mine site. Plate 2.0 <br />shows the conceptual drainage plan for Logan Wash Mine. Each drainage structure <br />(designated by "DS" on Plate 1.0) eventually dischazges stortnwater to a dischazge point <br />(designated by "DP") that conveys water to an offsite downstream area. Drainage <br />structures will consist of toe ditches or channels constructed on the mine roads and <br />benches. A discharge point physically refers to the outlet structure that conveys <br />stormwater to an offsite location, e.g. a natural drainage. The following paragraphs <br />describe the subbasins and the proposed drainage structure(s). The design of each <br />drainage structure is discussed in detail in Section 3.0 <br />Area 1 and Area 11: <br />Area 1 is a moderately vegetated upper slope area immediately above Area 11, the <br />sparsely vegetated Daylight Portal area. Runoff from Area 1 potentially drains to Area <br />11, The combined runoff from Areas 1 and 11 will be conveyed by a drainage channel <br />(DS 1) located at the toe of the slope of Area 11 to a pour-off point (DP 1) into Area 7. <br />Area 2 and Area 12: <br />Area 2 is a moderately vegetated upper slope area immediately above Area 12, the Upper <br />Bench. Runoff from Area 2 drains from the highwall at its base to drainage structure <br />DS2, a drainage channel located at the base of the highwall on the Upper Bench. Runoff <br />from Area 12 also drains to DS2. The combined runoff from Areas 2 and 12 will be <br />conveyed by the drainage channel to a pour-off (DP2) into Area 7. Depending on final <br />grade, the DS2 structure may convey a portion of flow to the pour-off at DP 1. <br />Area 3 and Area 13: <br />Area 3 is a moderately vegetated upper slope area immediately above Area 13, the wide <br />northern portion of the Upper Bench Road. A highwall separates Area 3 from Area 13. <br />The combined runoff from Areas 3 and 13 will be conveyed by a drainage channel (DS3) <br />Western Water 8 Land Inc. <br />