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SEDIMENT POND DESIGN • <br />C- <br />The sediment pond for the waste disposal area was designed by trial and error <br />using the SEDIMDT II model. The model was developed at the University of <br />Kentucky to estimate the suspended solids load in surface mine drainage. <br />Briefly, SEDINAT II is an event based model that calculates a hydrograph, <br />sediment graph, and a particle-size distribution for defined subwatersheds and <br />routes -:hem to a control structure. A brief discussion of the model will be <br />presented to assist Tn interpreting the results. However for a complete <br />descriptiion of the modeling components of SEDIMAT II refer to Barfield et al. <br />(1981) or Wilson et al. (1981). Following the model description, the methods <br />utilized in the sediment pond design will be presented. In the final <br />subsection the results of the analysis will be presented. <br />Model Description <br />In the formulation of the model the watershed is separated into a series of <br />junctions, branches. structures, and subwatersheds. A junction Ts defined . <br />simply ~~s where two or more streams meet with the separate streams being <br />defined as branches. A structure is the location along a branch of a sediment <br />control structure such as a sediment basin where a composite hydrograph, <br />sediment graph, and a particle size distribution are required to evaluate the <br />effectiv<:nes5 of the particular sediment control structure. A subwatershed is <br />simply i:he division of a total watershed into smaller basins. A runoff <br />hydrogra~~h is developed for each designated subwatershed based on a specified <br />design =storm event using the SCS curve number approach where a dimensionless <br />unit hycrograph is developed. The runoff hydrographs are routed to and <br />between structures by Muskingum's routing procedures. SEDIM]T II has two <br />different. options to calculate sediment yield: 1) MUSLE and 2) SLOSS. These <br />methods are briefly described in the following paragraphs. Sedirrent yield Ts <br />c_1 -_ .:-_'_ fir ecc.`. scb•,:a~ershad. rc;.teJ ,._ "-. - -.. -- -_... -~r.t ccntrci <br />structure. and combined to determine the total sediment entering the structure <br />from all upstream sources. A number of sediment control structures may be <br />evaluated and 'null' structures may be located at points where runoff <br />• hydrographs, sediment graphs, and sediment concentrations are desired. Output • <br />of interest at the designated structures consists of a combined runoff <br />