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I <br />TABLE 13-5-3 <br />/ ' <br />Weighted "k" Factor <br />i <br />Pond 009 Watershed <br />Soil Type k <br />468, 46C, 46D 0.2j <br />XBD, XBE, XBF 0.25 <br />1 <br />12C, 12D, 12E 0.25 <br />34C, 34D, 34E, 34F 0.24 <br />35C, 35D, 35E 0.24 ' <br />53C, 53D, 53E, 53F 0.26 1 <br />66D, 66E, 66F 0.25 <br />101 0.08 ~ <br />103 0.23 <br />5103 0.27 <br />Topsoil Removed 0.24 <br /> Total <br /> Weighted Average k = 105.47 = 0.24 <br /> 438.55 <br />Area (Ac) k x Area <br />9.79 2.15 <br />131.23 32.81 <br />4.47 1.12 <br />10.17 2.44 <br />8.85 2.12 <br />28.90 7.51 <br />42.80 10.70 <br />13.82 1.11 <br />44.76 10.16 <br />23.56 6.36 <br />120.80 28.99 <br />438.55 105.47 <br />Precipitation and Storm Type. The precipitation amounts at the Seneca II-W Mine permit <br />area for the 10-year and 25-year storms were obtained from NOAA Precipitation Frequency <br />Atlas Precipitation - Frequency Atlas of the Western States - Volume II - Colorado, 1973. <br />A standard SCS Type II storm was utilized for each analysis. <br />Unit Hydrograph and Surface Condition. The SEDCAD computer program provides three unit <br />hydrograph shapes to choose from in determining the runoff characteristics of a watershed. <br />The disturbed hydrograph (FAST) was used to generate a worst case hydrograph. <br />Time of Concentration. The time of concentration, tc, is defined as the time required for <br />water to flow from the hydraulically most remote point in the watershed to the watershed <br />outlet. <br />The time of concentration for Pond 009 was calculated using the following equation <br />(Barfield et al., 1983). <br />r1 <br />~J <br />J <br /> <br />13-5-4 <br />