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4-34 <br />• 4.5.3.3.3 Munger Mine Portal <br />The mine portals are located well above the main channel <br />of Munger Creek. The 500-year flood peak of Plunger Creek <br />near the mine portals is about 135 cfs (see Figure 4.5-5). <br />Flow depths for this flood will be less than 5 feet; whereas, <br />the mine portal is more than 20 feet above the channel <br />bottom. Therefore, no flood hazard exists from Munger Creek. <br />The small drainage south of the bench area will be diverted <br />around the bench on the west to a culvert under the access <br />road. This diverison channel elimiritates any flood hazard <br />at the mine portal. The local drainage area immediately <br />surrounding the mine portal is small, on the order of 3 acres. <br />Runoff from this area can be accommodated by the local <br />• drainage and settling pond system; no flood hazard is present <br />due to local drainage. In summay, there is no significant <br />flood hazard at the mine portal from any of the channels in <br />the area. <br />The flood hazard at the waste rock disposal area was evaluated <br />in more detail and is described in the following subsection. <br />4.5.3.3.4 Waste Rock Disposal Area ' <br />The flood hazard at the waste rock disposal area was evaluated <br />by estimating the limits of the 100-year floodplain of Munger <br />Creek near the disposal area. The study indicates that the <br />existing channel can contain even the 100-year flood; there <br />• is no danger that flood waters will enroach on the planned <br />