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<br />30 <br />1. <br />r <br />from erosion of the diversion channels. The runoff from disturbed and reclaimed <br />areas are either drained internally or captured by sediment ponds. <br />For post-mining conditions, the sediment concentration entering and leaving <br />the G.E.C. permit area is approximately the same and has a magnitude of 9500 ppm. <br />Through the mine permit area, the sediment concentrations are approximately <br />9000 ppm. Therefore, hydrologic impacts to the Magpie Creek drainage will be <br />minimized once the major diversion channels are restored. <br />5.3 monitoring Station Data <br />One precipitation event has occurred since the submittal of the Preliminary <br />Data ease Report; the event vas large enough to produce measureable runoff. Pre- <br />cipitation gauges 1 and 3 recorded 1.5 and 1.B inches of rainfall respectively. <br />Locations of the precipitation gauges are shown on Hydrology Map 1, Appendix A. <br />This precipitation event ves close to the two-year rainfall event with a duration <br />of six hours. Readings from crest stage gauges were obtained from the monitoring <br />stations on 'NO-Name" Creek above the mine site and on Magpie Creek below the <br />mine site. No indication of stream flow existed at the upper Newlin Creek mon- <br />itoring station. Using the rating curves developed for each crest stage gauge, <br />(General tk scription of Hydrology Report, Figures 4 and 5) the peak discharge <br />was estimated on 'No-Name' Creek and below the mine site on Magpie Creek. On <br />"NO-Name" Creek the recorded depth vas 0.64 feet which indicates a peak discharge <br />of approximately 50 cfa. On Magpie Creek below the mina site, a depth of 0.39 <br />feet vas recorded which indicates a peak discharge of approximately 23 cfs. One <br />possible explanation for the decrease in peak discharge is the attenuation of <br />the peak as it passed through the depression storage above the nine-foot culvert. <br />A suspended sediment sample was collected only at the monitoring station below <br />the mine site on Magpie Creek, The total suspended solids of this sample was <br />48,500 ppm. tSULTSED results show suspended solid concentrations of 35,000 ppm <br />at this location for the 10-year storm event. Even though this is the only <br />suspended solids sample collected, it shows that the MULTSED results are within <br />the range of actual occurring sediment concentrations. <br /> 5.4 Water Quality Analysis <br /> The precipitation event of the week of July 6, 1981, resulted in runoff <br /> below the Magpie Creek diversion ditch. A sample of this runoff was collected <br /> by the automatic bed sampler in this reach (Exhibit 1). Very high concentrations <br />