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• Roadside South Reclamation Drainage <br />Calculation Rational and Results Summary <br />Rational: <br />Calculated using SEDCADT"' 4 for Windows <br />Areas, slopes and flow paths obtained from electronic media, Exhibit 6C. The <br />500 scale diagram on the following page presents the subwatersheds. <br />The soil map, Exhibit 23 shows the soil type as 66 - "Torriorthents, Warm-Rock <br />Outcrop" and 4 "Barx Clapper complex". Generally the soil samples for this and <br />other disturbance areas indicates the soil is sandy to silty loam (Tab Section 9) <br />which equates to a "B" soil group. Clapper has a published soil group of "B" in <br />Table B-1 of Peak Flows in Colorado. The following CN's were used in the <br />calculations: <br />64 - B soil group, sage-grass with 20% cover. <br />86 - B soil group, fallow, bare soil. Used for topsoil piles, ponds <br />and reclaimed slopes. <br />100 year 24 hour storm event of 2.2" used for RSRDA upper diversion ditch <br />10 year 24 hour storm event of 1.4" used for all other run-off calculations <br />• The ditch layout and sizing are presented on Exhibits 6C and 26. The Upper Diversion <br />Ditch for RSRDA and the lower collection ditch #4 (Section H-H) both flow to the south <br />and discharge into and existing highway culvert. The peak flow from the Upper <br />Diversion Ditch is 8.83 cfs which represents the 100-year event. The peak flow from <br />the lower collection ditch #4 is 22.4 based on the 100-year event. The combined flow is <br />31.23 cfs. The 36" diameter highway culvert will handle 32.5 cfs, therefore it will handle <br />the design flow. <br />The Lower Collection Ditch, Northwest Ditch, Section D-D also discharges into a <br />highway culvert. The peak flow from this ditch is 0.88 cfs based on the 10-year event. <br />A 12-inch diameter culvert will handle 2.05 cfs with no head. The highway culvert is <br />larger than 12-inches so it will handle the design flow. <br />ENGINEER'S CERTIFICATION <br />The SEDCAD calculat~pP~~~~lR~mation presented on pages 14-6-1 through 14-6- <br />18ix were prepared 4~adf]?frlg'11Se°_~onth of November 2000 and January 2001, and <br />the information pres°~fi:tt~i's true af~•"g©rrect to the best of my knowledge and belief. <br />,.. <br />~, James E. StQy~r, P.E. Date <br />~~1st~red J?rofe~?;ional Engineer <br />• $€a~~%gf;;C6~gra~do No. 19230 <br />~.u.al <br />14-6-1 (Rev. 01 /01) <br />