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Notes for Calculations: <br />Exhibit 19(19) <br />Two New Culverts - TR -62 <br />Culverts C75 & C75 <br />Located in East Branch of RDA Upper Diversion Ditch <br />1. Culverts C75 and C76 are located in the east branch of the RDA upper diversion <br />ditch. <br />2. The culverts must be designed to handle the 4.2" 100 -year 24 -hour event. <br />3. The drainage area above the culverts totals 25.9 acres of undisturbed oak shrub <br />and 0.75 acres of disturbed area. <br />4. The undisturbed area has a Midnight soil classification, hydrologic soil group C. <br />5. Table 1 in Exhibit 15, Cover and production of RDA 9/84 lists 14.79% plant cover <br />for oak -shrub and 27.55% for Conifer Shrub. <br />6. A curve number of 74 was used for the undisturbed oak shrub based on a C soil <br />type and poor cover (Table 2.2d - Runoff curve numbers for arid and semiarid <br />rangelands, Oak - aspen). <br />7. A curve number of 94 was used for the disturbed area. <br />8. The following SEDCAD calculations show that culverts C75 and C76 will see a <br />peak flow of 51.82 cfs and will need to be 42 inches in diameter. (Pages 2 - 8) <br />ENGINEER'S CERTIFICATION <br />The calculations and information presented on pages EXH. 19(19) -2 through 19(19) -8 with <br />a date of 01/04/12 were - prepared by me during the month of January 2012, and the <br />information presentecyitime and correct to the best of my knowledge and belief. <br />S #ou�yL <br />I( q 2'aiti <br />t iat t es E toyer = Date <br />Reg istegOpfessional .Engineer <br />State ofIoradoNo'. 19230 <br />TR -62 Page EXH. 19(19) -1 01/04/2012 <br />