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Particles coarser than fine sand would not be transported off of the terrace during a 10-year, 24- <br />hour storm based on most particle size classes plotting within the area of no motion in Figure 4.6 <br />of OSM's publication "Design of Sediment Control Measures for Small Areas in Surface Coal <br />Mining", 1982 (assuming: roughness coefficient 1240, terrace slope 0.01, unit discharge from <br />terrace 0.008 cfs per foot of length). Discharge from the terrace would be filtered by the angular <br />rock on the slope immediately downhill from the terrace and by rock-lined ditches, and then <br />would be diluted by mixing with the runoff from the more than 10 acres of undisturbed areas <br />through which it would pass before leaving the permit area. <br />TR09, TR11, TR14, TR15 5-10a Revised 3/98, 8/02,12/06,1/08 <br />PPro.?e?/ Tit f /? <br />/4