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Rule 4.05.18, Steam Buffer Zones, mandates that mine related disturbance must <br />be 100 feet from an ephemeral stream with a drainage area greater than one <br />square mile unless the Division specifically authorizes surface or underground <br />mining operations closer. Munger Creek does have a drainage area greater <br />than one square mile and the disturbance associated with the refuse pile is within <br />100 feet of Munger Creek. However, the collection ditches and sediment pond <br />described above will assure that the surface coal mining operations will not cause <br />or contribute to the violation of applicable water quality standards. Additionally, <br />after reclamation, the sediment pond will remain in place until it can be <br />demonstrated that untreated drainage from the reclaimed area will contribute <br />fewer suspended solids to streamflow or runoff outside the permit area as <br />compared to untreated drainage from the adjacent area and sediment pond <br />removal is authorized by the Division. <br />The drainage area of the sediment pond is about 0.03 square miles. The <br />drainage area of Munger Creek near the sediment pond is 6.5 square miles (ref. <br />table 4.5-6). Based on this large difference in drainage areas, any water <br />contained in the sediment pond will not have a measurable impact on the <br />• quantity of water in Munger Creek. <br />The area not to be disturbed along the south bank of Munger Creek will be <br />clearly marked with Stream Buffer Zone signs. <br />The original permit document analyzed the flood hazard at the refuse disposal <br />area, see 4.5.3.3.4. The flood hazard was reevaluated by estimating the limits of <br />the 100-year plain of Munger near the disposal area. The study confirms the <br />original study's conclusion that there is no danger of flood waters encroaching on <br />the planned disposal area or related facilities. <br />The flood hazard used the flood discharge values listed in Table 4.5-6. Cross- <br />sections of the channel were determined from topography maps at five locations. <br />Manning's equation was used to determine the flow depth at each cross-section. <br />The average slope between each cross-section was used in the calculation. <br />Cross-section location and the extent of the floodplain are shown on Figure 2.2- <br />6. Cross-sections are shown on Exhibit 2.2-7. Flow calculations are presented <br />in Appendix M(vii) beginning at page 52. <br /> <br />M" 2.2-12ii 9/02 <br />