Laserfiche WebLink
• The design parameters and factors used to determine the peak discharge <br />and runoff volumes for each pond are summarized in the Sedimentation <br />Pond Hydrology and Sedimentology Calculations. The calculated discharge <br />and runoff values are also contained in this section. <br />Triangular hydrographs were computed for the existing ponds by using the <br />peak rate of runoff and adjusting the time base to obtain the previously <br />computed volume. The time base of the hydrographs were divided by 2.65 <br />to obtain the time of the rising limb. in accordance with the SCS <br />National Engineering Handbook, Section 4, Chapter 16. As an example, <br />the inflow hydrograph to Pond E is shown on the Sedimentation Ponds - <br />Hydrology and Hydraulics Map, (Plate II). Tributary areas, curve <br />numbers, and the volume and peak discharge rate for the 10-year. <br />25-year, and 100-year storms for each pond are also summarized on the <br />Sedimentation Ponds Hydrology and Hydraulics Map, (Plate II). <br />• SEDIMENTOLOGY <br />30 CFR 816.46(b) provides two (2) methods for computing required <br />sedimentation volumes. The first method calculates a value by <br />multiplying 0.1 acre-feet per acre by the total number of disturbed <br />acres during the mining and reclamation activities. This method was <br />used to determine the sedimentation volume for each of the existing <br />ponds. The second method provided is use of the Universal Soil Loss <br />Equation, however, this method was not utilized in this analysis. The <br />calculated sediment volume for each pond is listed in the Sedimentation <br />Pond Hydrology and Sedimentology Calculations and in the Pond Schedule <br />on the Sedimentation Ponds - Kerr Coal Mine Map. (Plate I). <br />r1 <br />LJ <br />23-18 <br />