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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 500 scale <br />diagram on the following page presents the subwatersheds. <br />The soil map, Exhibit 23 shows the soil type as 66 - "Torriorthents, Warm-Rock Outcrop" <br />and 4 "Bari Clapper complex". Generally the soil samples for this and other disturbance <br />areas indicates the soil is sandy to silty loam (Tab Section 9) which equates to a "B" soil <br />group. Clapper has a published soil group of "B" in Table B-1 of Peak Flows in <br />Colorado. The following CN's were used in the calculations: <br />64 - B soil group, sageyrass with 20% cover. <br />86 - B soil group, fallow, bare soil. Used for topsoil piles, ponds and <br />reclaimed slopes. <br />98 - B Soil Group, bare. Used for mine bench. <br />77 - B Soil Group, medium cover. Used for reclaimed refuse pile, <br />portion of lower parking area and reclaimed slopes. <br />85 - B Soil Group, gravel. Used for new access road. <br />100 year 24 hour storm event of 2.2" used for RSRDA upper diversion ditch, and ditches <br />• F, G, I, J and R <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 Ditch for <br />RSRDA and the lower collection ditch #4 (Section H-H) both flow to the south and discharge into <br />an existing highway culvert. The peak flow from the Upper Diversion Ditch is 8.83 cfs which <br />represents the 100-year event. The peak flow from the lower collection ditch #4 is 16.83 based <br />on the 100-year event. The combined flow is 25.66 cfs. The 36" diameter highway culvert will <br />handle 32.5 cfs, therefore it will handle the design flow. <br />ENGINEER'S CERTIFICATION <br />The SEDCAD calculations and informatiogg sented on pages 14-6-1 through 14-6-10 were <br />prepared by me during the months 00 and January 2001. Pages 14f-11 <br />through 14-6-18xxiii were prepare~9 P~~ ' pervision during the months of June and <br />July 2006. The information pre'~s true a_ °__ ct to the best of my knowledge and belief. <br />State of <br />I• <br /> <br />