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TABLE 13-4A-3 • <br />Weighted "k" Factor <br />2ond 011 As- Buili <br />Sotl Map Unit Hyd -Gcp k-Factor Area IACI <br />Spoil <br />Undisturbed B <br />B 0.24 <br />0.16 33 <br />107 .36 <br />.91 <br />Prec:Fit al ion and Stem ?ype Th,e FreciFitacion amounts at the Yoast Ft. ne permit area for <br />the 1U-year, 25-year, and 100-year storms were ottained from IJOAA E'r ecipiiacion <br />Frequency Atlas Precipitation - Frequency Atlas of the western S[aies - Volume II - <br />Colorado, 1973. A standard SCS T}'pe I1 storm was ucili=ed for each analysis. <br />Unit Hyd rograph and Surface Co nditio r, The SEGCAD~ computer program provides three unit <br />h yd rograph shapes to choose from in dot =_r mining the runoff characteristics of a <br />watershed. <br />Time of Conwntcaiicn The time of co r.c eni ratio n, to, is defined as the time required for <br />water to flow from the hydraulically most remote point in the watershed [o the watershed <br />ouil ei. <br />The time of concentration for Pond 011 was calculated using the SEDCAD` computer program. <br />The proq ram determines overland flew to a pond structure by utilizing the Seven SCS <br />Upland Curves which yield velocity as a function of slope and land use (Barfield et al., <br />19831. Lisced telow is a summary of t'r,e tims of concentracion for the subwatersheds. <br />Land Flow Vertical He ci zo ncal Slope l'e locity Time <br />Condition Dis[ (ftl Dist Ift) 18) (fps) Ihr) <br />.5 430 2200 19.55 4.43 0.14 <br />5 130 600 21.67 4.65 0.04 <br />a 270 190 14.1 5.65 0.09 <br /> Total Time of Concentration 0.267 <br /> 13-4A-4 Revised 12/12/97 • <br />